Author Topic: My Experiences Reflowing Videocards (so far 100% success rate) (Read 126269 times)

iamdarkyoshi · « **on:** February 16, 2016, 05:23:04 am »

So for christmas, instead of asking for parts for my gaming PC and stuff, I asked for a good soldering iron/reflow station. So I ended up with a unit of crummier quality to this one http://www.ebay.com/itm/853D-Rework-Soldering-Station-SMD-Hot-Air-Iron-Gun-DC-Power-Supply-6-Gifts-/252027806219?hash=item3aae07220b:g:uRQAAOSwu4BVphKX

But I mean it works great, much better than guess and check with the 20 year old two temp heat gun and my old weller 40w plug-in iron.

So first, I determine if the GPU needs a reflow in the first place. I run it, if it artifacts, almost certainly a reflow is needed. If it simply shows no video or crashes under load, it might be a bad BIOS image, faulty voltage regulators, it could actually need a reflow, or is might just be broken beyond economical repair.

The PROPER way to fix stuff like this is a reball, but reballs are a HUGE pain.

So if it needs a reflow or I simply cannot figure out any other fix to try, I usually just dissasemble the card, remove anything that can melt (like plastic parts near the GPU die) clean it well, prop it up on my table with little tinfoil balls and slowly warm it up over the course of 3-10 minutes, depending on the board. I set my hot air gun to 270 degrees. I know this is a little high, but I think the calibration is a bit off on my unit.

Removable mobile videocards (imac/gaming laptops) are usually a 3 minute preheat. Desktop cards I usually give longer, so maybe 5-10 minutes, and large laptop boards might even need more. The goal here is even heating to minimize thermal expansion strain across the board.

After preheating, I "go in for the kill." This is where I slowly move the nozzle closer to the GPU chip, trying to keep it evenly heated and the surrounding area warm as well. Once I work my way about 3/4in away from the chip, I keep applying heat for a couple minutes, again, more time for the larger boards as they contain lots of copper and will sink the heat, making it harder for the solder to melt and reflow.

After this, I slowly back out in the same procedure as before. After slowly cooling it down by moving the hot air gun farther away, once I get about 2 feet away and the board is under 100 degrees, away I usually put a cardboard box or something over it and let it cool down on its own for another 10 minutes. The key is NOT to rush.

After this, it is time to put it back together and test it! Apply new thermal paste, thermal pads, and make sure everything is fastened properly. Put it in the machine and boot it up!

So far I have fixed:
R9 270x
Three iMac video cards
HD4850x2

And nothing has yet to fail after a reflow so far. I know there are plenty of things I should do differently, but I have learned all of this through experimentation. Feel free to drop a comment or suggestion below, I look forward to hearing your opinions!

timb · « **Reply #1 on:** February 16, 2016, 01:23:46 pm »

Hehe...

Ian.M · « **Reply #2 on:** February 16, 2016, 01:42:40 pm »

The problem is: Any failed joints on any balls have cracked and the surface oxidized. When you reflow without adding flux, all you are doing is melting the solder balls, it does nothing to clear the oxides off the pad on the chip or the board (whichever side had the crack in the joint). It then cools to the solidus temperature and as it cools further the solder ball is squished against the oxidised pad it hasn't wetted by the contraction of the other balls and the resin underfill. This makes a pressure contact, and all appears OK, but solder cold-flows with pressure and time, so the contact pressure will decrease to zero. Add some thermal cycling and vibration and it will soon become bad again.

If the chip isn't underfilled, and you can ultrasonic clean the board then run some diluted no-clean rated liquid RMA flux under the chip, your chances of long-term success improve. Otherwise you have just thermally stressed the chip and the board to no good purpose.

ElektroQuark · « **Reply #3 on:** February 16, 2016, 01:45:38 pm »

Storm is coming...

wraper · « **Reply #4 on:** February 16, 2016, 02:27:11 pm »

Quote from: EdoNork on February 16, 2016, 01:45:38 pm

Storm is coming...

The question is how long they'll live after this procedure. Did you check if the solder has actually melted (by trying to move the chip)? It is very hard to heat a big BGA chip with such hot air station. Also, in most cases this is chip fail (bump ball fail inside the chip) rather than soldering fail. In such cases heating the chips usually revives them for some short time. So you can judge how successful those repairs were only after a year or two.
In cases when there was actual soldering fail, pads get oxidized and just melting the solder again, usually won't make them attracting the solder again.

iamdarkyoshi · « **Reply #5 on:** February 16, 2016, 04:48:51 pm »

Quote from: Ian.M on February 16, 2016, 01:42:40 pm

The problem is: Any failed joints on any balls have cracked and the surface oxidized. When you reflow without adding flux, all you are doing is melting the solder balls, it does nothing to clear the oxides off the pad on the chip or the board (whichever side had the crack in the joint). It then cools to the solidus temperature and as it cools further the solder ball is squished against the oxidised pad it hasn't wetted by the contraction of the other balls and the resin underfill. This makes a pressure contact, and all appears OK, but solder cold-flows with pressure and time, so the contact pressure will decrease to zero. Add some thermal cycling and vibration and it will soon become bad again.

If the chip isn't underfilled, and you can ultrasonic clean the board then run some diluted no-clean rated liquid RMA flux under the chip, your chances of long-term success improve. Otherwise you have just thermally stressed the chip and the board to no good purpose.

How would one ultrasonically clean the board? I have thought about running flux underneath the chip, but I have never heardnof someone doing it.

Ian.M · « **Reply #6 on:** February 16, 2016, 05:23:55 pm »

The whole board gets dunked in a tank of an appropriate cleaning fluid in an ultrasonic cleaner. What happens after that depends on the cleaning fluid used, but may involve rinsing with deionised water and/or IPA then low temperature hot air drying.

The hacks who think they can fix boards by reflowing them with a DIY store hot air gun or in their domestic oven don't have the knowledge and experience to know that flux helps, or if they do don't want to buy it by the litre, or how to select a suitable flux. The pros, either replace the chip, or if the chip is unobtanium, want the best possible chance of success so will remove it and reball it. Either way they get to clean the pads on the board and use their favourite SMD rework flux. Stuff that dies three months down the line will kill your reputation so they don't want to risk it - the job should be done right or rejected.

However as Wraper has pointed out, the odds aren't in your favour, because especially for high wattage chips, the failure is more probably the die attach bumps inside the package, rather than the substrate to PCB balls, as they are smaller and under a lot more thermal stress. Reflowing works if there is a board level mechanical design fault e.g too flexible a PCB that is distorted by the heatsink mounting or other pressure, otherwise the odds are poor.

iamdarkyoshi · « **Reply #7 on:** February 16, 2016, 10:14:55 pm »

Quote from: Ian.M on February 16, 2016, 05:23:55 pm

The whole board gets dunked in a tank of an appropriate cleaning fluid in an ultrasonic cleaner. What happens after that depends on the cleaning fluid used, but may involve rinsing with deionised water and/or IPA then low temperature hot air drying.

The hacks who think they can fix boards by reflowing them with a DIY store hot air gun or in their domestic oven don't have the knowledge and experience to know that flux helps, or if they do don't want to buy it by the litre, or how to select a suitable flux. The pros, either replace the chip, or if the chip is unobtanium, want the best possible chance of success so will remove it and reball it. Either way they get to clean the pads on the board and use their favourite SMD rework flux. Stuff that dies three months down the line will kill your reputation so they don't want to risk it - the job should be done right or rejected.

However as Wraper has pointed out, the odds aren't in your favour, because especially for high wattage chips, the failure is more probably the die attach bumps inside the package, rather than the substrate to PCB balls, as they are smaller and under a lot more thermal stress. Reflowing works if there is a board level mechanical design fault e.g too flexible a PCB that is distorted by the heatsink mounting or other pressure, otherwise the odds are poor.

I totally agree, this is why I sell my stuff with a one+ year warranty on reflow failures and I do include details in the ad that I had done a reflow on it and the expected lifetime before another repair can vary. I do put them under rigorous tests for at least a week, turning them off and on every once in a while just to really thermally torture it

crispy_tofu · « **Reply #8 on:** February 16, 2016, 10:35:27 pm »

Just putting this here:

wraper · « **Reply #9 on:** February 16, 2016, 10:38:21 pm »

This is not even a reflow. Without any flux presence nothing can even possibly reflow. You can call it 'reheating"at best.

AlxDroidDev · « **Reply #10 on:** February 16, 2016, 10:55:33 pm »

I, personally, prefer to buy GPUs with lifetime warranty (like the 2 EVGA GTX480 Superclocked I have) than have them undergo such dubious procedure.

I've had an old Asus Ti4600 (quite fancy for the time, but I bought on the grey market, without any warranty, and it died on my after 8 months) GPU reflown, but it only lasted for 6 months or so.

oldway · « **Reply #11 on:** February 17, 2016, 10:12:14 am »

The stupidity of some is such that a friend of mine said he was reballing GPU with a hair dryer and it worked.

Laughing, I gave him some solder and asked him to melt it with his hair dryer.

theelectronicegg.com · « **Reply #12 on:** February 17, 2016, 11:47:22 am »

i understand all the different problems...

but for some home user / gamer... it might give them another 3 month before needing to buy the next card...

just don't sell it as a repair service.

oldway · « **Reply #13 on:** February 17, 2016, 11:54:04 am »

Quote from: theelectronicegg.com on February 17, 2016, 11:47:22 am

...just don't sell it as a repair service.

And don't say you fixed it !!!!!!!!

samnmax · « **Reply #14 on:** February 17, 2016, 03:23:34 pm »

I'd also like to contribute my experiences with BGA "repairs".

I started with a Compaq Presario with a bad Radeon 9000. After attacking it with a 1000W heat gun from a distance, it booted, but with artifacts and crashed after a while. I tried to repeat it, but I got too enthusiastic and blew the chip up with too much heat. Luckily the GPU was replaceable so I got a new one.

Later on, I got a regulated heat gun that I used successfully to bring many laptops to (temporary?) life.
For most of them, I don't know how long they lasted, as they were from friends of friends. However, my uncles are using a Core 2 laptop with an ATI X1300 that has been reflown twice, first time lasted 2 years, let's see how long does the second pass work. I also fixed a BGA in a Seagate 2.5" hard drive, I use it regularly for non-important stuff.

Afterwards, I got a cheapass handheld hot air gun for SMD and some flux paste from Dealextreme, and I have to say that for the moment I only had success with them.

Recently I reflowed a GeForce 8600GT on a 17" Vaio. In this case I'm pretty sure the problem is in the chip bumps but hey, it worked, and allowed me to quickly recover the data off the laptop's RAID0 array. And a friend has a huge spare laptop to watch movies or so until it fails again (gaming forbidden

).

Skimask · « **Reply #15 on:** February 17, 2016, 07:16:21 pm »

Quote from: iamdarkyoshi on February 16, 2016, 05:23:04 am

So far I have fixed:
R9 270x
Three iMac video cards
HD4850x2

A sample size of 5.

Going by that logic, I fixed a Donkey Kong 3 arcade cabinet by reattaching a wire to the V-hold pot and re-cap'ing the monitor.
That means I also have a 100% success rate.

paulhm81 · « **Reply #16 on:** February 18, 2016, 06:31:11 am »

I usualy only heat up a gpu in laptops to confirm that the chip is the problem and if it works I outsource the gpu replacemet to a guy who does that for a living. A few years ago the reballing and reflowing business only gave me head headaches as it didn't work. Of the top of my head I would say that 90% of the laptops that had a reball came back after a few months. I refuse to reball or reflow them and the ones that get their gpu replaced are above 90% working 1 year later and I'm talking about 40-50 laptops!

gnasirator · « **Reply #17 on:** February 18, 2016, 08:32:47 am »

My experience:
2008 Macbook pro with nVidia GPU issue
- First try in IR-oven @ 220° - 7 min cycle: worked for about 1 week
- Second try in IR-oven @ 250° - 7 min cycle: worked for maybe two weeks
- third try in IR-oven @ 260° - 7 min cycle: same
- Last try in IR-oven @ 290° (max)° - 2x7 min cycle: still works (2 months ago)

Note: I shielded the whole PCB with aluminium foil and built a small square shield for the die as well during the last try.
My approach was, either it works or I get a new laptop which I would've needed then anyway. I'm glad it worked as I'd rather save the money until a good eGPU solution using Thunderbolt 3 is available.

iamdarkyoshi · « **Reply #18 on:** February 18, 2016, 05:44:50 pm »

Quote from: wraper on February 16, 2016, 10:38:21 pm

This is not even a reflow. Without any flux presence nothing can even possibly reflow. You can call it 'reheating"at best.

Fair enough, whatever it is, it seems to be working so far. I am aware of the issues though and do NOT sell them as repaired, but I do sell them as "I will either attempt to repair or replace it within a year of sale if it fails"

Bud · « **Reply #19 on:** February 18, 2016, 06:09:41 pm »

I have a GTX460 that failed after 4 years. It still has signal output on all connectors but only in VGA mode with the generic driver. As soon as i install the GPU driver (windows 7), i get a blue screen on reboot. It gets as far as "Loading Windows" message, then blue screen with "failed to reset the video card" sort of message. In VGA mode it shows in Device Manager as GTX460, so perhaps that means the system recognizes the GPU. I can also read the BIOS using nvflash utility. So i am not sure where to look or what to try to reheat/reflow, the GPU or memory ( do not want to torture the entire board in a IR oven, the board has plastic connectors). And this is not a power supply, computer or OS issue, tried it on a different computer with a monster power supply, also on a brand new Win 7 installation. Did anyone have experience with this sort of symptoms?

iamdarkyoshi · « **Reply #20 on:** February 18, 2016, 08:14:40 pm »

Quote from: Bud on February 18, 2016, 06:09:41 pm

I have a GTX460 that failed after 4 years. It still has signal output on all connectors but only in VGA mode with the generic driver. As soon as i install the GPU driver (windows 7), i get a blue screen on reboot. It gets as far as "Loading Windows" message, then blue screen with "failed to reset the video card" sort of message. In VGA mode it shows in Device Manager as GTX460, so perhaps that means the system recognizes the GPU. I can also read the BIOS using nvflash utility. So i am not sure where to look or what to try to reheat/reflow, the GPU or memory ( do not want to torture the entire board in a IR oven, the board has plastic connectors). And this is not a power supply, computer or OS issue, tried it on a different computer with a monster power supply, also on a brand new Win 7 installation. Did anyone have experience with this sort of symptoms?

What brand is it? It might be a reflow issue, but again, I cannot be sure. I look at it like "If its already fucked, there is no harm fucking it up further"

When you do a reflow, remove the little socket shell on the fan header, and the rest of the board should be able to handle reflow temps. The plastic used in them is supposed to handle the temps without melting.

Those fermi GPUs did run quite warm, so there is a chance that the thermal cycling is what caused the issue... Worth a shot I guess to attempt a "reflow"

Bud · « **Reply #21 on:** February 18, 2016, 08:38:06 pm »

Oh yes, the card has taken a lot of abuse from my teen son, several hours a day for 4 years in a row, Steam games and stuff, you can imagine. I think it did pretty well. It is an EVGA brand, Nvidia GPU.
I think i will try measuring the current consumption for any abnormal behaviour before going for a reflow. When i get the blue screen i can hear the HDD clicking, not sure if that is because the card may be short circuiting the power bus when the driver kicks in, in which case may be a problem with one of the onboard power regulators.

iamdarkyoshi · « **Reply #22 on:** February 18, 2016, 08:41:26 pm »

Quote from: Bud on February 18, 2016, 08:38:06 pm

Oh yes, the card has taken a lot of abuse from my teen son, several hours a day for 4 years in a row, Steam games and stuff, you can imagine. I think it did pretty well. It is an EVGA brand, Nvidia GPU.
I think i will try measuring the current consumption for any abnormal behaviour before going for a reflow. When i get the blue screen i can hear the HDD clicking, not sure if that is because the card may be short circuiting the power bus when the driver kicks in, in which case may be a problem with one of the onboard power regulators.

What happens if you use onboard gfx for the monitor and just leave the GPU in the system? Can you get drivers installed when the card is not being used to output video?

Ian.M · « **Reply #23 on:** February 18, 2016, 08:42:31 pm »

Possible bad caps?

Bud · « **Reply #24 on:** February 18, 2016, 09:09:47 pm »

I can leave it safely in the computer and use the computer's Intel HD graphics, no problems.
And I can install the driver while outputting generic VGA video through the card , not a problem, (still on VGA output after install before reboot), it is only when i reboot after installing the driver i get the blue screen. I then can boot in safe mode (again the card being in VGA generic mode) and disable or uninstall the driver.
Did not try installing the driver while on Intel HD graphics but i recall i cant do that because in the computer BIOS i have to set either onboard or PCI graphics to be used.

iamdarkyoshi · « **Reply #25 on:** February 18, 2016, 09:28:11 pm »

Quote from: Bud on February 18, 2016, 09:09:47 pm

I can leave it safely in the computer and use the computer's Intel HD graphics, no problems.
And I can install the driver while outputting generic VGA video through the card , not a problem, (still on VGA output after install before reboot), it is only when i reboot after installing the driver i get the blue screen. I then can boot in safe mode (again the card being in VGA generic mode) and disable or uninstall the driver.
Did not try installing the driver while on Intel HD graphics but i recall i cant do that because in the computer BIOS i have to set either onboard or PCI graphics to be used.

Can you set it to PCIe GPU and enable IGPU? This should let both run at once. Either way, something is wrong with the card. I would place my bets on a bad solder joint though. Try using NVFlash and flashing the latest manufacturer's BIOS, or get one from here: https://www.techpowerup.com/vgabios/

See if you can use the IGPU and see if the PCIe GPU is seen by the device manager still

Bud · « **Reply #26 on:** February 19, 2016, 08:31:15 am »

Nope, the computer did not allow run concurrently onboard and PCI graphics.
I switched back to using the card and measured the current. The board has two +12V rails. Did not notice excess power consumption. In VGA mode it just eats 1.2A+0.12A, and when the driver kicks in, right before blue screen 2.1A+0.3A. Anyway, i decided to double check the local voltage regulators. I pulled the card out and will try to power it from a bench power supply and check voltages. There seems to be 5 switching and a couple linear regulators on the card. Also just for the heck of it inspected the card under the microscope, found nothing worrying.

gnasirator · « **Reply #27 on:** February 19, 2016, 09:23:51 am »

Quote from: Bud on February 18, 2016, 08:38:06 pm

Oh yes, the card has taken a lot of abuse from my teen son, several hours a day for 4 years in a row, Steam games and stuff, you can imagine. I think it did pretty well. It is an EVGA brand, Nvidia GPU.
I think i will try measuring the current consumption for any abnormal behaviour before going for a reflow. When i get the blue screen i can hear the HDD clicking, not sure if that is because the card may be short circuiting the power bus when the driver kicks in, in which case may be a problem with one of the onboard power regulators.

Doesn't EVGA have lifetime warranty? I would get the card replaced!

Bud · « **Reply #28 on:** February 19, 2016, 02:09:45 pm »

I do not know, i'll check.

Stori · « **Reply #29 on:** February 19, 2016, 06:10:22 pm »

I'll throw in this youtube video:

Is that a proper reflow? The guy uses a cheap chinese infrared reflow station designed just for that purpose.

Rasz · « **Reply #30 on:** February 20, 2016, 05:27:48 am »

Quote from: Stori on February 19, 2016, 06:10:22 pm

I'll throw in this youtube video:

Is that a proper reflow? The guy uses a cheap chinese infrared reflow station designed just for that purpose.

>"I did at least 1600 this "type of repairs" on HP laptops and Im confideblablabla...98% success rate"

sure, hp dv6000, yeah, 98%!!1
typical cargo cult "I heat it up and it works ergo I fixed it case closed"

I bet people paid him for all those "repairs"

Bud · « **Reply #31 on:** February 20, 2016, 08:25:14 am »

OK, I got my GTX460 working...

The voltage regulators seemed to be OK so I moved to the GPU. I decided to try Louis Rossmann's advice and burned the chip at 120 C for 10 min. I do not have an preheater so I used a coffee warmer as the hot plate. That preheated the GPU to about 60C (measured at the package top) from the bottom then I used my hot air station to heat it from above for 10 min and monitored the package temperature with the Fluke meter. Then let it cool down naturally. Put it in the computer and -Bang!- it worked ! Pulled out one more time, applied thermal paste, installed the heatsink, put the card back and measured the current consumption.

With full GPU utilization the two +12V rails supplied 8.5A+2.6A, a total of about 11A, 133W or something.

Also took a peek with my Flir E4 thermal imager and found the major heat generation offender was actually the onboard power supplies, not the GPU, as can be seen in the attached pictures. The left picture is the card in idle mode (just Windows desktop), the right picture is the card under 99% GPU stress using a test utility. The power regulators are on the other side of the board under the fan cover and on full steam they heat the right side of the board right through to 80 C

while the GPU was almost 20 C cooler.

The card is not going to be used for games anymore, just for my Altium backup station, as such I do not expect the GPU to be stressed much, so hopefully the card will last for the next little while.

Stori · « **Reply #32 on:** February 20, 2016, 04:40:34 pm »

So the only way to fix a GPU properly in 99% of the cases is to replace it, is that correct?

iamdarkyoshi · « **Reply #33 on:** February 21, 2016, 04:53:18 am »

Quote from: Bud on February 20, 2016, 08:25:14 am

OK, I got my GTX460 working...

The voltage regulators seemed to be OK so I moved to the GPU. I decided to try Louis Rossmann's advice and burned the chip at 120 C for 10 min. I do not have an preheater so I used a coffee warmer as the hot plate. That preheated the GPU to about 60C (measured at the package top) from the bottom then I used my hot air station to heat it from above for 10 min and monitored the package temperature with the Fluke meter. Then let it cool down naturally. Put it in the computer and -Bang!- it worked ! Pulled out one more time, applied thermal paste, installed the heatsink, put the card back and measured the current consumption. With full GPU utilization the two +12V rails supplied 8.5A+2.6A, a total of about 11A, 133W or something.

Also took a peek with my Flir E4 thermal imager and found the major heat generation offender was actually the onboard power supplies, not the GPU, as can be seen in the attached pictures. The left picture is the card in idle mode (just Windows desktop), the right picture is the card under 99% GPU stress using a test utility. The power regulators are on the other side of the board under the fan cover and on full steam they heat the right side of the board right through to 80 C while the GPU was almost 20 C cooler.

The card is not going to be used for games anymore, just for my Altium backup station, as such I do not expect the GPU to be stressed much, so hopefully the card will last for the next little while.

Nice work! It will be interesting to see how long it lasts! Those fermi cards do run warm!

Quote from: Stori on February 20, 2016, 04:40:34 pm

So the only way to fix a GPU properly in 99% of the cases is to replace it, is that correct?

Unfortunately, pretty much.

Stori · « **Reply #34 on:** February 21, 2016, 07:49:44 pm »

What about the VRAM? Is the whole problem equivalent for the VRAM?

iamdarkyoshi · « **Reply #35 on:** February 22, 2016, 04:21:18 pm »

Quote from: Stori on February 21, 2016, 07:49:44 pm

What about the VRAM? Is the whole problem equivalent for the VRAM?

I have never seen the videoram have solder issues like the GPU die had, but it is not out of the realm of possibility...

Bud · « **Reply #36 on:** February 25, 2016, 05:25:00 pm »

Seems the famous xbox "towel trick" years ago may have used same "repair" mechanism as baking the GPU at low temp for 10-15 min. The trick involved wrapping the inoperable Xbox console in a towel and letting it sit for 10 min. Certainly that did not melt solder, but could raise the chip temperature inside console above a 100 degree. Google for "xbox towel trick" for posts/videos.

iamdarkyoshi · « **Reply #37 on:** February 25, 2016, 08:11:07 pm »

Quote from: Bud on February 25, 2016, 05:25:00 pm

Seems the famous xbox "towel trick" years ago may have used same "repair" mechanism as baking the GPU at low temp for 10-15 min. The trick involved wrapping the inoperable Xbox console in a towel and letting it sit for 10 min. Certainly that did not melt solder, but could raise the chip temperature inside console above a 100 degree. Google for "xbox towel trick" for posts/videos.

I have heard of that, pretty cringe-worthy

crispy_tofu · « **Reply #38 on:** February 29, 2016, 11:06:27 am »

Rasz · « **Reply #39 on:** February 29, 2016, 01:23:33 pm »

Quote from: crispy_tofu on February 29, 2016, 11:06:27 am

...

yay, repair tips from a guy who never even touched soldering iron, and uses good old cargo cult method of 'its broken, lets cook it'

iamdarkyoshi · « **Reply #40 on:** February 29, 2016, 04:03:59 pm »

Quote from: Rasz on February 29, 2016, 01:23:33 pm

Quote from: crispy_tofu on February 29, 2016, 11:06:27 am
...
-snip-

yay, repair tips from a guy who never even touched soldering iron, and uses good old cargo cult method of 'its broken, lets cook it'

Quote from: crispy_tofu on February 29, 2016, 11:06:27 am

...
-snip-

Yes, I also watch LTT
https://linustechtips.com/main/topic/552920-vessel-spoilers-psa-on-reflowing-videocards/

nogood · « **Reply #41 on:** February 29, 2016, 04:26:55 pm »

Quote from: Rasz on February 29, 2016, 01:23:33 pm

Quote from: crispy_tofu on February 29, 2016, 11:06:27 am
...

yay, repair tips from a guy who never even touched soldering iron, and uses good old cargo cult method of 'its broken, lets cook it'

After a few videos from that channel I am pretty convinced, that most of what they do is crap like that.
The "omg-our-quatripple-ssd-non-mirrored-raid-is-not-getting-detected"-video makes me think that guy is full of it, or they think their viewers are that stupid.

Back to topic:
Even if you can get half a year out of a "dead" video card it may be worth it. My only experience so far with that method was telling my brother to just try it with his notebook (crappy LG 17" pos with bad cooling) and it works to this day I think, but yeah only one is not enough for good statistics.
If your professional image doesn't ride on it, why not.

Stori · « **Reply #42 on:** March 02, 2016, 10:32:02 pm »

Just wanted to post that video but crispy_tofu was faster than me

here is Louis Rossmanns response to that video (headphone users be warned audio is kinda crappy and loud):

Fraser · « **Reply #43 on:** March 03, 2016, 01:03:21 am »

I just bought a Dell AIO 2205 motherboard for spare parts. It came from a computer repair centre as 'spares or repair' so I was expecting a pretty stuffed motherboard if they could not repair it.

I had to laugh when it arrived....... I now know exactly how Louis feels........

The motherboard has an intermittent video fault. The Northbridge is responsible for producing video on this AMD chipset and runs hot. As it is a flip chip, it would appear that maybe it has the bump issue or something else is intermittent on the PCB. I will never know though as some brainiac has heat gunned the Northbridge and also tried to apply more downward force to it via the heatsink screws. The brainiac obviously did not realise that tightening the heatsink screws does nothing as its a sprung system and the springs apply the pressure. Oh, he or she did manage to sheer off two of the PCB heatsink mounting threaded inserts in the process though. The board is total scrap as a result of this abuse.

Happily I only wanted it for some parts that have not been 'attacked'. Namely the BIOS, two multi-voltage rail generation chips and the system management IC. For £9 I am not complaining but it is further evidence that indiscriminate use of heat guns and daft 'magic' solutions can be very destructive.

I can understand Louis kicking off about this but sadly some people will never listen when they think that there is a cheap fix. Many amateur repairers cannot fit a new BGA chip, so for them it is just a case of getting paid for a 'repair' vs returning the computer to the customer with no payment. I am with Louis on this one though. Users can abuse their computer motherboards, that is their right....... Bona Fide repair techs who are charging for their work should do the job properly and replace the GPU or whatever other component that is causing the problem.

Fraser

Bud · « **Reply #44 on:** March 03, 2016, 07:47:01 am »

Louis should learn to manage his anger. It will get him in trouble one day if he won't.

Fraser · « **Reply #45 on:** March 03, 2016, 12:17:45 pm »

Having watched many of his videos I can say that, for the most part, Louis is calm and provides excellent commentary. Now and then he talks about a topic very dear to him, such as poor repair industry practices. Yes he gets a little over emotional in his delivery on such topics, but then so does Dave. Remember the PicKit 3 video Dave did. It is not unusual for people who believe strongly about a subject to get a little carried away...... Especially when making a You Tube video.

When you cut through the emotive stuff, the comments that Louis makes are valid. I did some research on flip chip design and the 'bump' contacts are a weak point. In production heat and compression is used to form the connections via conductive polymer, so I can see why a temporary fix results from reheating. Not a great long life design for a hot GPU.

I watched the video that Louis was so annoyed about........ My opinion of the what I saw...... A bunch of clowns messing with stuff they do not understand. They were just copying someone else's instructions without doing any research into what was being attempted or achieved. In doing so they are just spreading misinformation.

Fraser

iamdarkyoshi · « **Reply #46 on:** March 03, 2016, 04:32:09 pm »

Quote from: Fraser on March 03, 2016, 12:17:45 pm

Having watched many of his videos I can say that, for the most part, Louis is calm and provides excellent commentary. Now and then he talks about a topic very dear to him, such as poor repair industry practices. Yes he gets a little over emotional in his delivery on such topics, but then so does Dave. Remember the PicKit 3 video Dave did. It is not unusual for people who believe strongly about a subject to get a little carried away...... Especially when making a You Tube video.

When you cut through the emotive stuff, the comments that Louis makes are valid. I did some research on flip chip design and the 'bump' contacts are a weak point in the design. In production heat and compression is used to form the connections via conductive polymer, so I can see why a temporary fix results from reheating. Not a great long life design for a hot GPU.

I watched the video that Louis was so annoyed about........ My opinion of the what I saw...... A bunch of clowns messing with stuff they do not understand. They were just copying someone else's instructions without doing any research into what was being attempted or achieved. In doing so they are just spreading misinformation.

Fraser

I agree here. I am a LTT nerd with over 7K posts on their forums, and I made a post about this discussion here, I should probably link it in my signature over there.

all_repair · « **Reply #47 on:** March 03, 2016, 04:56:56 pm »

Quote from: Fraser on March 03, 2016, 12:17:45 pm

When you cut through the emotive stuff, the comments that Louis makes are valid. I did some research on flip chip design and the 'bump' contacts are a weak point. In production heat and compression is used to form the connections via conductive polymer, so I can see why a temporary fix results from reheating. Not a great long life design for a hot GPU.

Is GPU using flip chip? Or just BGA? I can't comment on Loius repair comments as every case may be different. From what I seen on repair video made by the China repairmen, the BGA chip needs to be reballed with lead-based ball, and then resolder. If the bond-wires are inside the ceramic, or plastic packaging, these wires should not be the weakest links.

Rasz · « **Reply #48 on:** March 03, 2016, 05:34:15 pm »

Quote from: all_repair on March 03, 2016, 04:56:56 pm

From what I seen on repair video made by the China repairmen, the BGA chip needs to be reballed with lead-based ball, and then resolder. If the bond-wires are inside the ceramic, or plastic packaging, these wires should not be the weakest links.

and the myth continues, amazing

Fraser · « **Reply #49 on:** March 03, 2016, 05:51:31 pm »

@all_repair,

My comment relates to flip chip designs. These are what Louis is talking about. The fully encapsulated ceramic and plastic case formats do not use the same bump technology (afaik).

As for repairing a BGA chip through re-balling it....... at hat is only the solution if it has in fact got some form of solder failure situation and not just an internal fault or associated component failure.

I think Louis has explained this in his previous videos on the topic. From what I have seen, Louis is ticked off with people automatically reaching for some form of hot air gun, IR heater, or oven, before investigating the most likely cause of the failure, and taking appropriate action from a position of knowledge rather than assumption. I can relate to that.

I stated, I have no issue with someone cooking their own PCB but I do take a dim view of someone calling them self a component level repair technician blasting chips with heat in the hope of a quick fix and fast buck. As Louis says, it does the industry no good to have such cowboy practices prevalent within it.

Fraser

SeanB · « **Reply #50 on:** March 03, 2016, 06:43:31 pm »

Having destroyed a fair number of BGA packages I will say there are never bond wires inside, just the flip chip on the PCB, so the join must be either a solder ball onto the silicon or a conductive epoxy.

I just today took apart a DECT phone, and gently desoldered the RF pcb, using a gentle application of heat from a MAPP torch. The 2 sided SRBP base board ( 1.6mm thick with conductive ink through hole vias and tenting top and bottom) did survive the gentle heating with only minor charring, though I did desolder a lot of the SMD components inside the screening cans of the RF board, it rattled after it fell to the floor, there were loose chips and capacitors inside the steel screening can. I can understand doing this to a BGA will fix it temporarily, though perhaps taking it to 1000C was not the best method.

wraper · « **Reply #51 on:** March 03, 2016, 07:02:32 pm »

Quote from: SeanB on March 03, 2016, 06:43:31 pm

Having destroyed a fair number of BGA packages I will say there are never bond wires inside, just the flip chip on the PCB, so the join must be either a solder ball onto the silicon .

If BGA have not extremely high terminal count, very likely it will be with bond wires. Especially those with thicker package type.

janoc · « **Reply #52 on:** March 03, 2016, 07:28:52 pm »

Quote from: Stori on March 02, 2016, 10:32:02 pm

Just wanted to post that video but crispy_tofu was faster than me
here is Louis Rossmanns response to that video (headphone users be warned audio is kinda crappy and loud):

That's one pissed dude! But agreed 100%.

iamdarkyoshi · « **Reply #53 on:** March 03, 2016, 07:39:18 pm »

Quote from: Fraser on March 03, 2016, 05:51:31 pm

@all_repair,

My comment relates to flip chip designs. These are what Louis is talking about. The fully encapsulated ceramic and plastic case formats do not use the same bump technology (afaik).

As for repairing a BGA chip through re-balling it....... at hat is only the solution if it has in fact got some form of solder failure situation and not just an internal fault or associated component failure.

I think Louis has explained this in his previous videos on the topic. From what I have seen, Louis is ticked off with people automatically reaching for some form of hot air gun, IR heater, or oven, before investigating the most likely cause of the failure, and taking appropriate action from a position of knowledge rather than assumption. I can relate to that.

I stated, I have no issue with someone cooking their own PCB but I do take a dim view of someone calling them self a component level repair technician blasting chips with heat in the hope of a quick fix and fast buck. As Louis says, it does the industry no good to have such cowboy practices prevalent within it.

Fraser

I usually use "reflows" as a last resort, I first perform the golden rule: "Thou Shall Check Voltages"

I test the VRMs first, then I see if I can reflash the BIOS. If the VRMs show normal voltages and the bios could be flashed and verified, then the next thing to try is a "reflow"

Rasz · « **Reply #54 on:** March 03, 2016, 09:01:51 pm »

Quote from: wraper on March 03, 2016, 07:02:32 pm

Quote from: SeanB on March 03, 2016, 06:43:31 pm
Having destroyed a fair number of BGA packages I will say there are never bond wires inside, just the flip chip on the PCB, so the join must be either a solder ball onto the silicon .
If BGA have not extremely high terminal count, very likely it will be with bond wires. Especially those with thicker package type.

good picture, now for all the "lets cook it fans":
Nvidia was caught, and forced to pay for recalls several times, using bad underfill material resulting in cracked balls between die and package due to thermal cycle stress.

http://www.theinquirer.net/inquirer/news/1013947/why-nvidia-duff-chips-shoddy-engineering
http://semiaccurate.com/2010/07/12/nvidia-backpedals-gf100gtx480-underfill/
and so on

Cooking gpu works by softening underfill and relieving stress accumulated from all the hot-cold 20-90"C cycles. What you end up with is a GPU with CRACKED balls, but reformed underfill allowing contact/conducting. It will work for some time if not stressed thermally.

visual explanation:

This is not a fix, this is plumbing with duct tape, or fixing engine by smashing at it with a hammer.

Why does it sometimes work on non gpu stuff? cooking can temporarily heal dead capacitors and make contact in cracked solder joints (thermal expansion) - 'problems starting, works when warm'.
Extreme cooking (450"C heatgun lol) could (if you are lucky not to destroy whatever you are working on) remove tin whiskers and reflow cracked rohs joints, and I could do ballet. There are even cases of "fixing" 8051 controller chips with cooking:
https://www.eevblog.com/forum/chat/how-could-a-mems-gyroscope-get-fixed-by-heating-it-up/msg705547/?topicseen#msg705547
somehow heating this chip to 450"C heals semiconductor structure??

iamdarkyoshi · « **Reply #55 on:** March 03, 2016, 09:17:01 pm »

Quote from: Rasz on March 03, 2016, 09:01:51 pm

Quote from: wraper on March 03, 2016, 07:02:32 pm
Quote from: SeanB on March 03, 2016, 06:43:31 pm
Having destroyed a fair number of BGA packages I will say there are never bond wires inside, just the flip chip on the PCB, so the join must be either a solder ball onto the silicon .
If BGA have not extremely high terminal count, very likely it will be with bond wires. Especially those with thicker package type.

good picture, now for all the "lets cook it fans":
Nvidia was caught, and forced to pay for recalls several times, using bad underfill material resulting in cracked balls between die and package due to thermal cycle stress.

http://www.theinquirer.net/inquirer/news/1013947/why-nvidia-duff-chips-shoddy-engineering
http://semiaccurate.com/2010/07/12/nvidia-backpedals-gf100gtx480-underfill/
and so on

Cooking gpu works by softening underfill and relieving stress accumulated from all the hot-cold 20-90"C cycles. What you end up with is a GPU with CRACKED balls, but reformed underfill allowing contact/conducting. It will work for some time if not stressed thermally.

visual explanation:

This is not a fix, this is plumbing with duct tape, or fixing engine by smashing at it with a hammer.

Why does it sometimes work on non gpu stuff? cooking can temporarily heal dead capacitors and make contact in cracked solder joints (thermal expansion) - 'problems starting, works when warm'.
Extreme cooking (450"C heatgun lol) could (if you are lucky not to destroy whatever you are working on) remove tin whiskers and reflow cracked rohs joints, and I could do ballet. There are even cases of "fixing" 8051 controller chips with cooking:
https://www.eevblog.com/forum/chat/how-could-a-mems-gyroscope-get-fixed-by-heating-it-up/msg705547/?topicseen#msg705547
somehow heating this chip to 450"C heals semiconductor structure??

Man this is why I love the EEVBlog forum. Such an expansive amount of neat info to learn!

all_repair · « **Reply #56 on:** March 04, 2016, 01:17:33 am »

Quote from: Rasz on March 03, 2016, 09:01:51 pm

Quote from: wraper on March 03, 2016, 07:02:32 pm
Quote from: SeanB on March 03, 2016, 06:43:31 pm
Having destroyed a fair number of BGA packages I will say there are never bond wires inside, just the flip chip on the PCB, so the join must be either a solder ball onto the silicon .
If BGA have not extremely high terminal count, very likely it will be with bond wires. Especially those with thicker package type.

good picture, now for all the "lets cook it fans":
Nvidia was caught, and forced to pay for recalls several times, using bad underfill material resulting in cracked balls between die and package due to thermal cycle stress.

http://www.theinquirer.net/inquirer/news/1013947/why-nvidia-duff-chips-shoddy-engineering
http://semiaccurate.com/2010/07/12/nvidia-backpedals-gf100gtx480-underfill/
and so on

Cooking gpu works by softening underfill and relieving stress accumulated from all the hot-cold 20-90"C cycles. What you end up with is a GPU with CRACKED balls, but reformed underfill allowing contact/conducting. It will work for some time if not stressed thermally.

visual explanation:

This is not a fix, this is plumbing with duct tape, or fixing engine by smashing at it with a hammer.

Why does it sometimes work on non gpu stuff? cooking can temporarily heal dead capacitors and make contact in cracked solder joints (thermal expansion) - 'problems starting, works when warm'.
Extreme cooking (450"C heatgun lol) could (if you are lucky not to destroy whatever you are working on) remove tin whiskers and reflow cracked rohs joints, and I could do ballet. There are even cases of "fixing" 8051 controller chips with cooking:
https://www.eevblog.com/forum/chat/how-could-a-mems-gyroscope-get-fixed-by-heating-it-up/msg705547/?topicseen#msg705547
somehow heating this chip to 450"C heals semiconductor structure??

I know Rasz that you have a lot to share. Thanks.
I am getting ready to do BGA rework but so far there is no immediate need. Checking the type of bonding that the BGA packaging uses shall be crucial in determine course of actions

all_repair · « **Reply #57 on:** March 04, 2016, 03:56:01 am »

I have been keeping an iMac Intel 17" 1.83GHz that has a GPU problem for a while. I have fixed the supply problem, and used it for another a year ore moew. My plan is to use this to practise on BGA reflow and reball. I don't have the GPU part number, and could not find it online so far, to check on the type of its BGA packaging.

Just wondering is this GPU worth trying?

MyHeadHz · « **Reply #58 on:** March 04, 2016, 07:03:48 am »

Before an old GPU died I noticed the temp was always high, but no matter what I did it stayed high... even maxing out the fan speed... turning off the fan... nothing at all changed it. I had chalked it up to a failed temp sensor till the GPU finally failed and I found my culprit! (see attached)

I cleaned out the fan first thing. I used a Radio Shack heat gun to reflow it, and I never had any more problems from it. My first reflow! <3

As far as GPU's go, when I was finally ready to upgrade I remembered the reflow experience. I went on craig's list and found a dead r9 280x for $30 and picked it up (at the time they went for ~$400 USD). After a quick reflow and some new upgraded thermal paste it's been doing great ever since! Approaching 2 years now. That saved me hundreds! In case you are wondering, it was modded for bitcoin mining and the warranty was void (hence the cheap price).

For both I used an infrared thermometer and heat gun to heat everything to my desired goal temps. Then, I went through with a soldering iron and hit up a few key points that I thought were especially important.

Sure it isn't ideal, but it works just as well as a new one. It overclocks very well and holds it with no artifacting. If it fails again, I'll just reflow. A lot of people look down on reflowing, but for stuff like this I honestly see no downsides.

I've also reflowed and thermally optimized (internal ducting, thermal compound upgrades, shielding, etc) lots of things... xbox's, playstations, and lots of other electronics over the years (for me and friends). I originally bought several broken xbox's to test out my skills. I got all of them working, and to date nothing that I've ever reflowed has failed. The only down side is the extra space the spare xbox's take up in storage :p

I even reflowed the fuel pump relays on my F-150. I put 50k miles on it after that with no issues whatsoever. That alone saved me thousands. It has since been retired to live out the rest of its days on the farm :p Actually, resoldering would probably be a more accurate term for what I did there. I sucked the flux, put new proper leaded solder and flux. The lead-free crap was probably the reason it failed in the first place.

crispy_tofu · « **Reply #59 on:** March 04, 2016, 09:14:13 pm »

Apparently LinusTechTips followed up with Louis

Fraser · « **Reply #60 on:** March 04, 2016, 09:37:29 pm »

Good to see

Fraser

Stori · « **Reply #61 on:** March 05, 2016, 07:10:38 am »

Wow nice, I never would have thought that

Bud · « **Reply #62 on:** March 05, 2016, 10:17:14 pm »

Folks, prepair to vote for Motherboard Repair Party in the next elections.

iamdarkyoshi · « **Reply #63 on:** March 05, 2016, 11:45:40 pm »

Quote from: Bud on March 05, 2016, 10:17:14 pm

Folks, prepair to vote for Motherboard Repair Party in the next elections.

They would get my vote

Bud · « **Reply #64 on:** March 06, 2016, 07:39:02 am »

I'd like to share my observation about poor thermal paste application that I found on two totally different products, one was a may be 4 years old Dell laptop with Nvidia chip, the other was a PCi-E EVGA card that I revived, also with Nvidia GPU. Both had insanely thick layer of dried grey thermal paste, I guess it is of a popular Silver Arctic brand. It was more than 1 mm thick. I think such improper use of thermal paste may have contributed to the malfunction of the Nvidia GPUs. Once the paste dries out it may become an isolator and the chip just slowly fries itself. Perhaps it may make sense after a year or two pull the card out and change the thermal paste, if the card is out of warranty.

MyHeadHz · « **Reply #65 on:** March 06, 2016, 08:29:14 am »

yeah, too much thermal paste is an insulator. And yes, if it dries it will also lose thermal conductivity. However, not all thermal compound "dries" like that.

It is also worth noting that changing the thermal compound only voids the warranty of some brands of graphics cards. That is also an important factor to check when buying one, especially considering how poor the thermal compound is of some graphics cards.

Rasz · « **Reply #66 on:** March 06, 2016, 07:46:50 pm »

Quote from: Bud on March 06, 2016, 07:39:02 am

It was more than 1 mm thick. I think such improper use of thermal paste

what you saw was quite proper 3m thermal pad, maybe 2-4C difference between that and thin fresh thermal compound.

Bud · « **Reply #67 on:** March 06, 2016, 07:55:46 pm »

Could have been a pad on the Dell but certainly paste on the EVGA, squeezed from under the heatsink and hanging from all four sides of the chip.

Russ314 · « **Reply #68 on:** May 26, 2017, 04:47:56 pm »

First off - my apologies for dredging this up, but I really want to add some pertinent info to an otherwise very informative thread.

Oh, and as for the comments about "cooking" chips with a 450*C heat gun - those guns are barely hot enough to cook dinner, let alone a GPU. I regularly assemble SMD boards using standard Sn63/Pb37 solder, and 450*C is almost the exact temperature I use. I can set the gun to 800*F and blast the fresh SnPb paste until the cows come home, but it's not going to melt. 850*F is where I like to be. I even go as high as 900*F for smaller parts (0805, SOD-123, etc.). I use a large expansion (NOT reduction!) nozzle btw. Without the nozzle, the temp would probably have to be >1,000*F for lead-free solder, and that's approaching the limit of the gun.

If anyone wants to figure out the exact heat-gun conversion ratio, just pour a small amount of distilled water into a test tube, and try to boil it. Common sense will have you start with temps near ~220*F, but you'll quickly realize that 220*F is not even hot enough to burn your hand. In order to make the water boil, you'll have to get the gun to around 400*F. Since water boils at 207*F in my area (Los Angeles), that means the conversion factor is about 2:1. In other words, to create a 420*F reflow profile, you'll have to set the gun to 420*2 = 840*F.

So that's the first thing. More to the point of the thread, I want to explain that I've figured out the (actual) permanent fix for GPU issues. I've been using my Vaio laptop all day everyday for the past 10 years, and during that time, I've had to reflow the GPU about 10 times. It was after that tenth time that I finally discovered the real fix. That was 18 months ago, and since then, my laptop has worked better than it did when it was new. Here's what I did:

1. Reflow the GPU. I won't tell you how, since you already know. I will say that I didn't have my "good" Steinel heat gun at the time, so I had to use a cheap Harbor Freight gun. After a very, very long thermal soak period, I put the heat on "high" and held it point-blank against the GPU for 28 seconds. I was going for 30 secs, but I started to hear sizzling/popping noises... I backed the gun off and held it there on "low" for less than a minute, then put away the gun and wrapped the laptop in several layers of thick blankets so that it could cool to room temp as slow as possible. It's also worth noting that I drowned the board with Kester 951 before the reflow, but I'm not sure if that helped. It hadn't helped in the past. After reading this thread, I guess I know why.

2. This is critical - BEND THE SPRINGS on top of the thermal cover/pad that rests on top of the GPU. Bend the springs upward, so that whatever you bolt on top will press downward with maximum force. On my laptop, there is a large cast metal heatsink (for the GPU RAM) that bolts on top. By bending the springs upward, I made the cast metal part push the GPU pad aggressively against the GPU. This is a big part of the permanency of the fix. I don't know whether pushing on the GPU forces out more thermal paste, which closes the gap, which increases heat transfer from the GPU, or whether the force squeezes the GPU package and closes any internal gaps/cracks. Those are both ideas I hadn't thought of until reading this thread. To be honest, my reason for doing it was that I wanted the GPU to be held in place for whenever the solder melted again. After all, the reason for the GPU failure was gravity. When the GPU overheated, it would DE-solder if the laptop was right-side up, and RE-solder if the laptop was upside-down. So I figured the added spring pressure would counter the force of gravity and hold the chip against the board.

3. Since the cast metal heatsink/GPU cover is dangerously close to the bottom of the laptop, I wanted to make sure it never experienced any mechanical shock when the laptop was moved/handled/etc. This fix was easy - I just bought a $20 padded plastic thing that sits on my lap, and my laptop rests on top of it. This proved to be one of my best purchases ever, because now I can bounce my laptop around all day without ever having to worry about the GPU (or other internals) being stressed or compressed in any way. The pad also provides a constant air gap for the fan intake. It also protects my sperm

.

So that's it. Reflow the GPU, bend the springs, and get a base/pad thing. Even a portable kitchen cutting-board would work. I don't know whether it was the springs or the pad that helped the most, but I suspect it was a combination of both. One thing I know for sure is that my previous reflow attempt used the same heat gun, on the same setting, in the same manner (but for only 20 seconds, not 28), and with the same flux, and the repair only worked for maybe a month or two. Btw, I also toyed with all the GPU settings via nVidia's software (e.g. clock speed, frame rate, etc.), but nothing I did affected the GPU temp, so I wouldn't bother with any of that.

Since the fix, the GPU temp has been rock solid. It used to constantly go up and down 30 - 40 degrees, but now it only moves 10 degrees (F). And the fan almost never comes on. Before the fix, the fan would constantly wind up and scream for mercy, but now I never hear it. The only thing that raises GPU temps is watching Youtube vids in full-screen (which I never do). Watching small-sized Youtube vids won't even cause the fan to increase from its idle state.

Hope this info helps someone!
Sincerely,
Your friendly local embedded Microchip engineer turned organic chemist turned couch bum

Russ314 · « **Reply #69 on:** May 27, 2017, 06:27:55 am »

I just tested the heat gun in a formal experiment. I'm too tired to post a full write-up, so here's a summary of my lab notes:

Heat Gun: Steinel HL2010E (not recommended)
Temperature Setting: 800*F
Airflow setting: LOW
Nozzle: 75mm "Spreader Nozzle"
Distance from nozzle to work surface: 1.0"
Method of temperature measurement: thermocouple (i.e. a kitchen thermometer, with the probe laid flat on the work surface directly below the nozzle output)

TIME TEMP (*C)
T=0 24.9
T+30 86.6 <-- The gun reached 800*F at exactly 30 secs
T+60 142.8
T+90 169.1
T+2min 178.6
T+2.5 187.3
T+3min 193.2
T+3.5 205.9
T+4min 210.8
T+4.5 212.6
T+5min 213.9
T+5.5 215.1
T+6min 216.7
T+6.5 218.3
T+7min 218.5
T+7.5 222.1
T+8min 220.3
T+8.5 219.6
T+9min 220.4
T+10min 219.1

As you can see, it's a pretty good reflow profile. Starts to reflow after 2 to 2.5 minutes, and peaks at ~210*C after 4 minutes. Leaving it on for a full 10 mins only adds a few more degrees beyond that. At the 10 min mark, I switched the gun to "cool down" mode, and it took 2 mins 10 secs to cool all the way back to 120*F.

I would like to amend my previous post btw; 850*F is a bit too high. I tried it and it melted the white plastic SMD connectors on the board before it melted the solder. Dropping the temp to 800*F worked perfectly, and the plastic never melted/singed/discolored again.

Hopefully this clears up once for all the myth about cooking/scorching/incinerating/vaporizing IC's with 450*C heat guns.

P.s., I know the pics are convoluted, so I'll elucidate. The heat-gun is attached to the chemistry lab ring stand with two clamps, while the third (articulating) clamp holds a laser. The laser is CRUCIAL for the success of the setup. You really need to know where the center-line of the airflow is, because being off by even a few millimeters will drastically reduce the effective reflow temperature, and it'll also unbalance the air forces that keep the components pinned down. If you move even slightly out from the center-line, the tiny parts will blow around. That's how I settled on the 1.0" nozzle distance btw - I found that the limit for my setup was 0.920", and moving any closer caused my smallest components (0805 resistors) to blow around.

KL27x · « **Reply #70 on:** May 28, 2017, 08:58:20 pm »

Quote

So that's the first thing. More to the point of the thread, I want to explain that I've figured out the (actual) permanent fix for GPU issues. I've been using my Vaio laptop all day everyday for the past 10 years, and during that time, I've had to reflow the GPU about 10 times. It was after that tenth time that I finally discovered the real fix. That was 18 months ago, and since then, my laptop has worked better than it did when it was new. Here's what I did:

Basically, unless you discover an actual fix like you have, using improvements to the mechanical fixtures, fixing a board simply thru reflow isn't going to fix the underlying problem. Problem with Louis take/rant on it... if the flip chip is failing because it uses a bad underfill..... what is the point of insisting you have to replace it with a genuine replacement part which also has a bad underfill in it and will also fail... If you want to disassemble/reassemble your laptop more than once in a lifetime to keep it operating, you have way too much time on your hands, lol. This makes top 10 list of things I don't want to do with my time. By third time, I will be ready to professionally disassemble laptop with sledgehammer and landfill solution. This is why Louis is so angry, no doubt. If I can't charge $500.00 for just opening a laptop, I'm not gonna enjoy doing it, at all.

rx8pilot · « **Reply #71 on:** May 28, 2017, 09:25:25 pm »

It is hard to imagine that it is financially productive to do these repairs as a business, although I guess some people have figured it out. I do a lot of 'in-house' repairs on various pieces of commercial gear that are very difficult or impossible to replace outright. I do a LOT of design, prototyping, and small lot production so I have all the tools and experience needed to do BGA re-work and I would be hesitant to dive that deep into a laptop or desktop computer. Just disassembly and re-assembly takes a long time and the repair can always end up being a rabbit hole adventure.

Russ314 · « **Reply #72 on:** May 30, 2017, 01:15:33 am »

Quote from: KL27x on May 28, 2017, 08:58:20 pm

This makes top 10 list of things I don't want to do with my time.

I hear that. For me, it ranks just slightly below going to the dentist.

Quote

By third time, I will be ready to professionally disassemble laptop with sledgehammer

That reminds me of my first laptop... It was a 1997 Dell Latitude, and the screen broke after only 2 years. I wasn't able to fix it, so I ended up removing the CD-ROM drive and stuffing the hole with 18 grams of perchlorate explosives. I set it off in my backyard and the damn thing nearly vaporized. 30 minutes later, I was walking around on my roof, picking up coin-sized fragments of plastic and metal, and putting them in my shirt (which I had folded upwards and was holding in my teeth). Out of nowhere, a cop car came FLYING up to the front of my house, slammed the brakes, and turned on a powerful spotlight (it was dusk by then), and started combing back and forth across the front of my house. All I could do was freeze in place. Incredibly, the cop (who was focused on my kitchen windows and the bushes around them), somehow failed to notice me standing there, like a deer in the headlights, holding an armful of evidence.

Ah, yes... the good ol' days

By the way, I spent all day yesterday reflowing small surface-mount boards, using the setup I previously posted. One thing I've learned is that attempting to map a definitive correlation between the temperature setting of the gun, the temperature reading of the thermocouple, and the actual temperature transmitted to the board/solder is a pointless endeavor. At the exact point when the solder reaches 173*C (reflows), the heat gun says 427*C, and the themocouple says 105*C. So the readings are all pointless. All I can say for sure is that the 800*F setting seems to work best if you want to reflow with a heat gun.

rx8pilot · « **Reply #73 on:** May 30, 2017, 04:30:56 am »

I use temperature indicating crayons to help me heat a pcb with a reasonable profile. It takes a lot of guessing and complexity out of the task.

Sent from my horrible mobile....

Russ314 · « **Reply #74 on:** May 30, 2017, 07:25:39 am »

Quote from: rx8pilot on May 30, 2017, 04:30:56 am

I use temperature indicating crayons to help me heat a pcb with a reasonable profile.

That's a good idea. What temperature(s) do you use? I just checked Amazon... those damn things are expensive! Some of them are listed for over $125?! For a crayon??

The "Thermomelt" sticks seem cheaper than the "Tempilstik" equivalent. Are those the only two brands? I'm thinking I should get one for 400*F (205*C) to let me know when I'm at peak temp.

EDIT:
Here is the Amazon price for a 463*F Thermomelt stick...

Quote

List Price: $181.04
Price: $9.85
You Save: $171.19

I call shenanigans.

rx8pilot · « **Reply #75 on:** May 30, 2017, 04:27:17 pm »

Quote from: Russ314 on May 30, 2017, 07:25:39 am

Quote from: rx8pilot on May 30, 2017, 04:30:56 am
I use temperature indicating crayons to help me heat a pcb with a reasonable profile.

That's a good idea. What temperature(s) do you use? I just checked Amazon... those damn things are expensive! Some of them are listed for over $125?! For a crayon??

McMaster Carr $13.64/ea

575F (a little over 300C) is what I try not to exceed at the PCB.
300F (150C) is a good guess where flux activates. This is about the 60-second countdown where you should be flowing.
437F (225C) this is just before the flow begins with Pb solder

I generally just cut off some tiny pieces and put them on the board. They were helpful to understand my batch oven profiles as well as for re-work and 1-off hand placed prototypes.

Russ314 · « **Reply #76 on:** June 02, 2017, 12:01:03 am »

My 212*C Markal Thermomelt stick arrived in the mail today. It is, without a doubt, the worst item I have ever purchased on Amazon. I've spent the past hour trying to make it work. I've literally tried everything I can think of to make it melt, but all it does is out-gas (spew white vapor), or char and turn black, or crumble into sawdust-like pieces and blow away. Out of frustration, I tried melting it with a torch, but it instantly caught fire and burned. The worst part of the ordeal is that the vapor it emits is a skin irritant, so my arms currently feel like I was grinding pink fiberglass insulation into them.

In a last-ditch effort to make it melt, I cranked up my heat gun to 1,000*F, and ran it for 9 minutes. The thermocouple reached 247*C, but the Thermo-"melt" just sat there as if I was trying to melt drywall.

rx8pilot · « **Reply #77 on:** June 02, 2017, 12:07:34 am »

Wow! That is rotten.

Ian.M · « **Reply #78 on:** June 02, 2017, 06:40:52 am »

I'd complain about that. It sounds like it could be fake.

Sn-Ag-Cu ternary eutectic lead free solder melts at 217 deg C, other Sn-Ag-Cu near-eutectic compositions melt within a few degrees of that.

Cut or scrape the Thermomelt stick to expose a fresh surface and try melting a piece of Sn-Ag-Cu solder against it with a freshly cleaned and tinned bit (using the same solder), you should see the surface start to fuse just before the solder melts.

N.B. Thermomelt sticks are intended to be 'chalked' on a lightly roughened surface before that surface is heated, and may not give a useful indication if used in bulk or if directly heated. See http://www.ksdistribution.com.sg/ksd/wp-content/uploads/pdfs/atoes_products/E2.%20Laco%20Markal/Thermomelt.pdf

Russ314 · « **Reply #79 on:** June 02, 2017, 11:40:03 pm »

Quote from: Ian.M on June 02, 2017, 06:40:52 am

Thermomelt sticks ... may not give a useful indication if used in bulk or if directly heated.

*sigh* That's exactly the conclusion I arrived at, after dicking with it for 6 straight hours yesterday. I assumed it was like wax, and would melt/solidify around a set temperature. In reality, it's a binary material, consisting of flux and powdered chalk. The only time it actually melts is if the mixture is thermally shocked, and changes temperature instantly. If you try to slowly heat it to melting temperature, the flux component evaporates, leaving behind the unaltered chalk. You can see in one of the pics where I broke a piece open, and you can clearly see how the "spent" outer shell protected the inside material.

Also note the white powdery condensate. That is the flux residue. Even when the stick is used "properly," the flux instantaneously evaporates into a giant cloud of white vapor, which engulfs your face and burns your eyes and sinuses similarly to hydrogen chloride (a.k.a. acid vapor). It also condenses on your skin, covering your body with a thin layer of plastic-y material. If you've ever spray-painted, you'll know what it feels like when paint mist sticks to your arm hairs. It creates a sticky, uncomfortable feeling. That's what this flux does. I had to shower twice yesterday (and wash my face 5 times) because I kept getting coated every time I messed with it, and I refused to stop messing with it. I wouldn't attempt to use this stuff without a bionic face shield (although that didn't protect my face entirely).

Also note the pic that shows a thousand crumbles - that's what happens if you try to use the stick like a crayon. If the metal isn't quite hot enough, it simply turns the stick to... it's like when your laundry or dish detergent gets damp, and it forms a solid clump - but the clump easily explodes back into granules? That might be a bit esoteric, but that's what this stick does. Most of the smaller granules blew away, so the ones in the pic are just the larger pieces that remained in the area.

One of the few times I got it to melt is shown in the pic with the zinc-plated bolt. I heated the bolt with a blowtorch for a while, then melted the stick on it. It successfully melted, released a cloud of vapor, then turned into a chalky layer that very closely resembles dried toothpaste. It's worth noting that this method only seems to work on steel. Heating copper or aluminum with a torch, and then rubbing the stick on it, only caused the stick to crumble. The only other time I got the stick to melt properly was when I rubbed it along the stainless steel thermocouple probe (seen in the pics). It wouldn't, however, melt on the adjacent aluminum plate (which was much hotter than the steel probe).

Btw, I don't own (nor have I ever used) lead-free solder. A few years ago, after exhaustive research, I decided to use lead-based solder in all my products, because I concluded that it's better than lead-free in every way (including environmental and health safety concerns). If anyone has a few hours to spare, this article is a good read: https://nepp.nasa.gov/whisker/reference/tech_papers/2011-kostic-pb-free.pdf. I tend to think of NASA as a reliable source.

So here's the million-dollar question: is Tempilstik any better?

debininja · « **Reply #80 on:** June 03, 2017, 12:16:27 am »

I originally thought this trick would work, but unfortunately, it does not, at least, not permanently. The fix is only temporary. I bought a used GTX580 off eBay for $60 (for Vegas CUDA rendering. Apparently the Fermi cards were the last to support it). 6 months afterwards, it stopped working.

I set my hot air gun to 240C and directed the airflow on and around the GPU for close to 20 minutes, popped it back in and...it worked! I was thrilled. Unfortunately, it stopped working again after 2 months. So I did the same thing, but this time I set it to 250C and ran it over 5 minutes, alternating between cooling and re-heating, for 20 minutes. Popped it back and...and it worked! But it stopped working again after 2 weeks, and that's when I got fed up and chopped it off the PCB.

Now I plan on using the original, sexy looking beefy heatsink on the assembly, strap on a bunch of power mosfets, and build an Arduino powered constant current, constant resistance, and constant power load assembly. (Basically, it'll look like a real GTX580, but with the guts missing). Add some CCFL lighting all around it and it'll look really slick.

Rasz · « **Reply #81 on:** June 03, 2017, 12:31:44 am »

Quote from: debininja on June 03, 2017, 12:16:27 am

I originally thought this trick would work, but unfortunately, it does not, at least, not permanently.

of course it doesnt, whole thread is pretty stupid, even nVidia admitted the chips are internally defective

Armadillo · « **Reply #82 on:** June 03, 2017, 01:20:57 am »

Quote from: Russ314 on June 02, 2017, 11:40:03 pm

So here's the million-dollar question: is Tempilstik any better?

In the photo, the tube thing, is that the thermo-sensor? I think the thermo response will be so laggy in such a heavy thermal mass assembly over a very doubtful air/heat distribution system in terms of even temperature distribution by the look of it.
Forget about Nyquist stability criterion with such laggy system, I supposed its hand controlled.

It's just my view base from my first impression, but I am sure you have your design theory and reasons in doing those.

Oogway · « **Reply #83 on:** June 03, 2017, 03:08:47 pm »

Quote from: Russ314 on May 26, 2017, 04:47:56 pm

2. This is critical - BEND THE SPRINGS on top of the thermal cover/pad that rests on top of the GPU. Bend the springs upward, so that whatever you bolt on top will press downward with maximum force. On my laptop, there is a large cast metal heatsink (for the GPU RAM) that bolts on top. By bending the springs upward, I made the cast metal part push the GPU pad aggressively against the GPU. This is a big part of the permanency of the fix. I don't know whether pushing on the GPU forces out more thermal paste, which closes the gap, which increases heat transfer from the GPU, or whether the force squeezes the GPU package and closes any internal gaps/cracks. Those are both ideas I hadn't thought of until reading this thread. To be honest, my reason for doing it was that I wanted the GPU to be held in place for whenever the solder melted again. After all, the reason for the GPU failure was gravity. When the GPU overheated, it would DE-solder if the laptop was right-side up, and RE-solder if the laptop was upside-down. So I figured the added spring pressure would counter the force of gravity and hold the chip against the board.

Wondering if this reflow with added pressure method would work with a GTX 1070. Bending the springs back to add pressure and keep the underfill in place a bit better. Could you expand on this a bit more?

wraper · « **Reply #84 on:** June 03, 2017, 03:14:32 pm »

Quote from: Rasz on June 03, 2017, 12:31:44 am

Quote from: debininja on June 03, 2017, 12:16:27 am
I originally thought this trick would work, but unfortunately, it does not, at least, not permanently.

of course it doesnt, whole thread is pretty stupid, even nVidia admitted the chips are internally defective

Especially considering it never reached solder melting temperature.

Rasz · « **Reply #85 on:** June 03, 2017, 06:10:32 pm »

Quote from: Oogway on June 03, 2017, 03:08:47 pm

Wondering if this reflow with added pressure method would work with a GTX 1070. Bending the springs back to add pressure and keep the underfill in place a bit better. Could you expand on this a bit more?

to completely destroy your card? yes
this thread is a scam

Oogway · « **Reply #86 on:** June 04, 2017, 02:28:41 am »

To be fair though...it's already destroyed. I've seen your posts and I know you know what you're talking about but the only alternative is throwing it in the garbage. Unless you know of another way to fix the underfill issue?

Rasz · « **Reply #87 on:** June 04, 2017, 04:12:54 am »

Pascal (GTX 1070) doesnt have underfill issues (that I or anyone else in the industry heard of)
make new topic about your card and describe problem in full, or return it for warranty replacement

Oogway · « **Reply #88 on:** June 05, 2017, 09:38:55 pm »

Quote from: Rasz on June 04, 2017, 04:12:54 am

Pascal (GTX 1070) doesnt have underfill issues (that I or anyone else in the industry heard of)
make new topic about your card and describe problem in full, or return it for warranty replacement

Okay will do thanks Rasz

Sent from my XT1635-02 using Tapatalk

Oogway · « **Reply #89 on:** June 07, 2017, 03:41:43 pm »

New topic on my issue posted here if anyone is interested in following.

https://www.eevblog.com/forum/repair/gtx-1070-no-video-underfill-issue/

Russ314 · « **Reply #90 on:** June 17, 2017, 06:32:35 am »

Quote from: Armadillo on June 03, 2017, 01:20:57 am

Quote from: Russ314 on June 02, 2017, 11:40:03 pm
So here's the million-dollar question: is Tempilstik any better?

In the photo, the tube thing, is that the thermo-sensor? I think the thermo response will be so laggy in such a heavy thermal mass assembly over a very doubtful air/heat distribution system in terms of even temperature distribution by the look of it.
Forget about Nyquist stability criterion with such laggy system, I supposed its hand controlled.

It's just my view base from my first impression, but I am sure you have your design theory and reasons in doing those.

You don't SOUND sure... At any rate, the thermal mass of the probe is matched to the thermal mass of the populated boards. A fast-response probe (e.g. thermistor) would simply tell me the temperature of the air, which I already know (from the heat-gun readout).

Convective heat transfer is a bitch. I was actually hoping to fine-tune the temperature probe distance/placement so that it showed exactly 183*C when my boards began to reflow, but my "only melts at one temperature" thermal stick decided to "melt" across a huge, unpredictable range of temps.

Russ314 · « **Reply #91 on:** June 17, 2017, 07:31:33 am »

Quote from: Rasz on June 03, 2017, 12:31:44 am

even nVidia admitted the chips are internally defective

No one is denying that (despite your implication).

Quote from: Oogway on June 03, 2017, 03:08:47 pm

Wondering if this reflow with added pressure method would work with a GTX 1070. Bending the springs back to add pressure and keep the underfill in place a bit better. Could you expand on this a bit more?

I'll do you one better - I made you a picture. See attached.

Quote from: wraper on June 03, 2017, 03:14:32 pm

Especially considering it never reached solder melting temperature.

If you use the nVidia System Monitor to track GPU temps, you'll find that a faulty GPU will start to fail when the temperature is only ~75*C. If you use the "wrap your laptop in a blanket and flip it upside down" method to repair it, you'll find that the GPU heals itself at around the same temp. We can therefore conclude that the underfill epoxy begins to soften at a surprisingly low temperature. This method of fix will only be temporary though, because the solder balls beneath the die are still cracked, which means the circuit will fail again as soon as the GPU temperature exceeds ~75*C.

Quote from: Rasz on June 03, 2017, 06:10:32 pm

to completely destroy your card? yes
this thread is a scam

You seem like a very, very smart person; I had better not argue with you.

Russ314 · « **Reply #92 on:** June 17, 2017, 07:57:14 am »

See attached. I just screen-capped that from my system overview page. I've been using this laptop every day for the past 10 years.

I also checked my old maintenance notes, and can tell you definitively that the date of my last/final GPU fix was 7/16/2016. So its been exactly 11 months. Not as long as I remembered, but still a long time.

My GPU is currently 143*F, which is 5*F hotter than usual, but I'm doing a lot right now. I frequently watch Youtube vids and have no trouble with the GPU overheating. Compare that to before the "spring" fix, when a 5-minute Youtube vid would cause the GPU to overheat and fail. Even after a fresh heat-gun reflow, Youtube vids would always cause the GPU to overheat and fail.

I can't remember the last time the GPU/CPU fan spun up higher than its lowest state. Even doing frequent CAD work doesn't cause the fan to wind up.

Armadillo · « **Reply #93 on:** June 17, 2017, 08:04:36 am »

Quote from: Russ314 on June 17, 2017, 06:32:35 am

You don't SOUND sure...

No dude!, is just from my culture to be polite and allow you a face saving way out.

Quote from: Russ314 on May 26, 2017, 04:47:56 pm

If anyone wants to figure out the exact heat-gun conversion ratio, just pour a small amount of distilled water into a test tube, and try to boil it. Common sense will have you start with temps near ~220*F, but you'll quickly realize that 220*F is not even hot enough to burn your hand. In order to make the water boil, you'll have to get the gun to around 400*F. Since water boils at 207*F in my area (Los Angeles), that means the conversion factor is about 2:1. In other words, to create a 420*F reflow profile, you'll have to set the gun to 420*2 = 840*F.

Your theory is so much flawed. Even a low grade student will know that the water specific density and specific heat capacity are so much different from solder. You are at least 192 times OUT! You ought to start from the basic.

Quote from: Russ314 on June 17, 2017, 06:32:35 am

Convective heat transfer is a bitch.

The surface area of your probe is so huge and here you are bitching on convective heat transfer.

At any rate, No, you can't convince anyone with those...

WastelandTek · « **Reply #94 on:** June 23, 2017, 07:00:57 am »

Quote from: EdoNork on February 16, 2016, 01:45:38 pm

Storm is coming...

gawd...you called it

I just don't get all the vitriol. OK, sure, if someone is selling baking as a service, or baking something and immediately selling it that is messed up, granted. But I have had lots of success with my own equipment over the years, hell, there is an old 8800 over there /glances across room/ been faithfully flogging SETI at home for the last two years on a bake.

What the people who get their panties in such a bunch need to remember is that these cards were BROKEN, UTTERLY WORTHLESS E WASTE. Whatever the mechanism, I fail to see the problem with squeezing weeks, months, or indeed YEARS of service out of an otherwise useless device. Does the solder actually reflow? Is it the chip bumps? I could give a rip as long as the dammed thing boots and does what I want, which they frequently do, and if not, hey, IT WAS BROKEN ANYWAY.

Lolucoca · « **Reply #95 on:** June 24, 2017, 09:30:32 pm »

Had to reball some RAM chips last week, wasn't too bad since it was only a ~30 ball BGA...

flexy123 · « **Reply #96 on:** September 26, 2018, 11:57:17 pm »

Quote from: Russ314 on May 27, 2017, 06:27:55 am

I just tested the heat gun in a formal experiment. I'm too tired to post a full write-up, so here's a summary of my lab notes:

Heat Gun: Steinel HL2010E (not recommended)
Temperature Setting: 800*F
Airflow setting: LOW
Nozzle: 75mm "Spreader Nozzle"
Distance from nozzle to work surface: 1.0"
Method of temperature measurement: thermocouple (i.e. a kitchen thermometer, with the probe laid flat on the work surface directly below the nozzle output)

TIME TEMP (*C)
T=0 24.9
T+30 86.6 <-- The gun reached 800*F at exactly 30 secs
T+60 142.8
T+90 169.1
T+2min 178.6
T+2.5 187.3
T+3min 193.2
T+3.5 205.9
T+4min 210.8
T+4.5 212.6
T+5min 213.9
T+5.5 215.1
T+6min 216.7
T+6.5 218.3
T+7min 218.5
T+7.5 222.1
T+8min 220.3
T+8.5 219.6
T+9min 220.4
T+10min 219.1

As you can see, it's a pretty good reflow profile. Starts to reflow after 2 to 2.5 minutes, and peaks at ~210*C after 4 minutes. Leaving it on for a full 10 mins only adds a few more degrees beyond that. At the 10 min mark, I switched the gun to "cool down" mode, and it took 2 mins 10 secs to cool all the way back to 120*F.

I would like to amend my previous post btw; 850*F is a bit too high. I tried it and it melted the white plastic SMD connectors on the board before it melted the solder. Dropping the temp to 800*F worked perfectly, and the plastic never melted/singed/discolored again.

Hopefully this clears up once for all the myth about cooking/scorching/incinerating/vaporizing IC's with 450*C heat guns.

I apologize that I am quoting this in length, but it's needed for context.

So, I am experimenting with various "ghetto reflow" techniques recently, including semi reflow with a heat gun, and this post confuses me.

(My heatgun is similar to yours, it's a cheap 2000W one with two settings, low = 350C, and high is 550C)

I can't see why you need more than 3 minutes (!!) to even reach 200C. Further above you say even that you need to set your heat gun to 800F (425 deg C.) to be even able to melt anything. (Suggesting that anything below 800F wouldn't work). This contradicts all my own observations.

But then again, you may well be right, as you say somewhere "convection heat transfer is a bitch".

I used a thermocouple right above the chip, and it showed 210C, but of course this shows only the temperature of the hot air coming from the gun and is not an indication whether the PCB itself or whatever part actually has this temperature for "reflowing". Saying: It is *DARN DIFFICULT* to even assess the actual temperatures you're getting when you try a "reflow" with a heat gun. So even with a thermocouple to measure, I am still there where I was before.

If what you say is true that you need to set your H.G. to 450 deg C., then basically this means I can try "reflowing" at low (350 deg) until I am blue in the face, it won't ever reach the temp to actually do anything. (Now not considering that most of these "reflows" are in reality only fixing things by softening the underfill, which seems to be the actual problem in many cases)

Furthermore, I am confused why you use this odd spreader nozzle which basically spreads out into a thin line, so no surprise that moving the H.G. just a millimeter messes things up. Likewise, I'd consider this nozzle extremely impracticable if not impossible to "reflow", say a GPU chip. (How would you do this with this type of nozzle?).

Add: I see you're using a capillary thermo probe there, like those which are used in ovens. I am not a pro by a long-shot, but I wonder how accurately this would reflect the actual temps. I mean it's possible this is also not accurate (not better than the thermocouple) and/or that the setup is very "laggy" (as someone mentioned). It's just that the temps in your list and the times there to me make not much sense.

If I take what you say there as true, it would mean reflowing with a heat gun, if at all, would need MUCH higher temps, and a MUCH longer time, like 7-8 minutes at least until something even melts?

Regards

janoc · « **Reply #97 on:** September 27, 2018, 04:15:55 pm »

Quote from: flexy123 on September 26, 2018, 11:57:17 pm

If what you say is true that you need to set your H.G. to 450 deg C., then basically this means I can try "reflowing" at low (350 deg) until I am blue in the face, it won't ever reach the temp to actually do anything. (Now not considering that most of these "reflows" are in reality only fixing things by softening the underfill, which seems to be the actual problem in many cases)

...

If I take what you say there as true, it would mean reflowing with a heat gun, if at all, would need MUCH higher temps, and a MUCH longer time, like 7-8 minutes at least until something even melts?

I wonder that you even bother with these guys ... This nonsense is like religion - or audiophoolery.

At the temperatures in his "reflow profile" he wouldn't even have melted solder at the peak temperature of 210 C. Common lead-free solders don't even start to melt below 217 C or so and some mixtures often don't completely melt below 240 C - that is with perfect heating (like in an oven), not when you have tons of losses all over the place like with hot air. Even with a soldering iron lead-free is difficult to solder with the tip temperature set below 330-360 C.

Standard oven reflow profiles go up to 260 C for the actual soldering phase.

https://www.microsemi.com/document-portal/doc_view/131105-solder-reflow-leadfree

You have nailed it that all he is doing is melting the underfill (and cooking the board for minutes). Which, sometimes, "fixes" the problem for a while because it holds the cracked internal solder balls on the flip-chip carrier together, restoring electrical contact. Of course, it will work only until the next few thermal cycles cause it to move out of position again ... So much for such "reflow" repair.

WastelandTek · « **Reply #98 on:** November 18, 2018, 06:57:30 pm »

Getting cold here in the Northern hemisphere, recently went around and fired up all the "heaters"

Yep, that old 8800 mentioned above is still going strong, 3.5 years now. Good thing I listened to the experts and binned it back in...oh wait...

jacan · « **Reply #99 on:** January 15, 2019, 06:10:27 pm »

Quote from: WastelandTek on November 18, 2018, 06:57:30 pm

Getting cold here in the Northern hemisphere, recently went around and fired up all the "heaters"

Yep, that old 8800 mentioned above is still going strong, 3.5 years now. Good thing I listened to the experts and binned it back in...oh wait...

nice, can you tell me your average temps on the gpu? (idle and while gaming)

Russ314 · « **Reply #100 on:** February 15, 2020, 07:54:37 am »

I didn't realize this thread had kept going... I just wanted to give an update: my heat gun + "bend the springs" fix is still going strong. Been watching Youtube vids like a boss, and no sign of trouble. The days of dealing with a failing nVidia GPU are but a distant memory. Its been 3.5 years now; I think we can officially call that a "permanent" fix.

I'm too lazy to re-read this thread (plus I don't feel like arguing anymore), so I'll just add a few things. First - many of you are conflating heat-gun temperatures with reflow oven temperatures. My best advice would be to NOT fixate on the absolute numbers, and instead approach the issue from a heat-transfer perspective. Also - I now use this heat gun/ringstand setup to manufacture and sell my own electronics. Here is my method (which I have written down on an index card and taped to the wall):

1. Put a Hershey's Kiss shaped dab of MG Chemicals 4860P solder paste in the dead center of every pad.
2. Turn on the heat gun at 800*f to pre-soak the base plates. Turn the gun off when the base plate temp reading is 160*C.
3. Wait until the baseplate cools to 60*C, then add the PCB and let it soak.
4. Turn on the heat gun at 800*F and heat for 1 min 10 sec. The solder will just begin to flow at this point.
5. Increase the temp to 820*F and heat for another 15 sec.
6. Turn the heat gun off and very quickly move the PCB from the hot aluminum plate to the ringstand's cast iron plate for cool down

I have a 3" spreader nozzle on the Steinel, and I use a spacer tool to make sure the end of the nozzle is exactly 22.3mm from the surface of the aluminum base plate (which is sitting on the cast iron ringstand base). If I move the nozzle any closer, it will blow away the 0603 caps. This setup is what I use to reflow a double-side board that is 51mm long and 8.5mm wide (approx. the size of your pinky finger). The most thermally massive component on the board is probably a SOT-223. This is what I do for a living now; I'm not making this stuff up to trick some random strangers on an internet forum.

Quote from: flexy123

If what you say is true that you need to set your H.G. to 450 deg C., then basically this means I can try "reflowing" at low (350 deg) until I am blue in the face

My best overall advice is to not focus on the absolute numbers. The temperature setting, airspeed, nozzle type, nozzle distance, heat profile, etc. will have to be determined empirically. The process I've just outlined for making my own products will obviously not reflow a BGA. I know all the future lurkers are desperate for some exact, enumerated instructions for reflowing a BGA, but the truth is that you'll just have to experiment. I guess the good news about the BGAs is that it's so thermally massive that it's almost impossible to overcook them in situ. I remember once when I had the Harbor Freight gun maxed, at point blank, and I nuked the GPU until I heard something pop. You know, that unmistakable sound when an electrolytic or other small passive suddenly explodes. Luckily, it had no perceivable negative effects.

The ultimate takeaway from this thread should be the knowledge that you CAN solder with a heat gun, and you CAN use it to fix a faulty GPU. The temperature you set the gun to is borderline irrelevant; what matters is getting the heat energy into the solder. And don't forget to preheat. Preheating is critical. I use an old toaster-oven for preheating in many soldering/brazing/welding operations. Large pieces of thermally massive cast iron can also be used for this purpose. In other words, heat a chunk of cast iron (like a 45lb barbell plate) in your kitchen oven, then remove it, carry it to your garage, place it on an insulated surface, and put your laptop on top so it can soak.


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