Author Topic: Replacing BGA by milling it down?  (Read 8203 times)

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Offline WattSekunde

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Replacing BGA by milling it down?
« on: December 24, 2014, 07:55:59 pm »
I found this interesting iPhone repair video. Something like that I have not yet seen.

If you don't understand a word like me go to 6:50 where the milling work starts.

 

Offline flolic

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Re: Replacing BGA by milling it down?
« Reply #1 on: December 24, 2014, 08:40:11 pm »
Yes, that BGA chip is underfilled with epoxy and can not be removed by simply heating it.
 

Offline atferrari

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Re: Replacing BGA by milling it down?
« Reply #2 on: December 25, 2014, 04:19:27 pm »
Only in this video he has a fresh bottle of Chivas R (and a half empty glass) within reach on the shelf. Ready to celebrate?

I find "fast forward" videos tyring.
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Offline miguelvp

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Re: Replacing BGA by milling it down?
« Reply #3 on: December 25, 2014, 06:59:47 pm »
Only in this video he has a fresh bottle of Chivas R (and a half empty glass) within reach on the shelf. Ready to celebrate?

I find "fast forward" videos tyring.

He did take the shot before the video went to the milling process. But since I don't understand what he was saying I don't know if the presentation was after or before the repair.
 

Offline poorchava

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Re: Replacing BGA by milling it down?
« Reply #4 on: December 25, 2014, 07:40:27 pm »
Not having the latest and greatest test and repair gear doesn't mean anything. Eg, the toothbrush which he has on high workbench probably work same as well as special uber-duper-high-tech-electronics-grade-brush that costs $20 or something :). Looks like they have a proper brushless spindle (probably water cooled) fitted on that CNC by the way

« Last Edit: December 25, 2014, 07:43:54 pm by poorchava »
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Offline WattSekunde

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Re: Replacing BGA by milling it down?
« Reply #5 on: December 25, 2014, 09:44:10 pm »
Yes, that BGA chip is underfilled with epoxy and can not be removed by simply heating it.

Thanks, that's interesting. How was this initially soldered?
 

Offline WattSekunde

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Re: Replacing BGA by milling it down?
« Reply #6 on: December 25, 2014, 09:45:47 pm »
Only in this video he has a fresh bottle of Chivas R (and a half empty glass) within reach on the shelf. Ready to celebrate?

I find "fast forward" videos tyring.

Take a look to the first 10 videos on his channel.  ;)
 

Offline WattSekunde

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Re: Replacing BGA by milling it down?
« Reply #7 on: December 25, 2014, 09:55:11 pm »
Not having the latest and greatest test and repair gear doesn't mean anything. Eg, the toothbrush which he has on high workbench probably work same as well as special uber-duper-high-tech-electronics-grade-brush that costs $20 or something :). Looks like they have a proper brushless spindle (probably water cooled) fitted on that CNC by the way

Looking through other videos on this channel it's interesting what they do with basic equipment. But that's really what you need beside the personal skills. I am not sure how reliable the results are but it looks impressive.

I wonder where they get the replacement chips from.
 

Offline jaxbird

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Re: Replacing BGA by milling it down?
« Reply #8 on: December 25, 2014, 10:17:42 pm »
I've learned never to underestimate Asian engineers in a shed with crude tools, you'd think impossible or simply not worth the effort, then you ask them, they say, come back in 2 hours and when you come back, they've managed to debug, source parts and fix whatever you presented them with.

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Offline jaxbird

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Re: Replacing BGA by milling it down?
« Reply #9 on: December 25, 2014, 11:06:49 pm »
There's probably a million resourceful guys in China, India  and Asia in general making a living repairing things normally thrown out in developed countries with high labour costs. Just don't call it hacking, this is working for a living.

I find it fascinating to observe how things coalesce to create opportunities for  the right people. It is like seeing a plant growing and apparently thriving in a crack in the mortar.

Agree, you'd be surprised how many hours it makes sense to throw into e.g. a $100 motherboard, a $75 phone or a cheap laptop compared to just saying it's bad and replacing it.

Lots of people make a living repairing cheap "throw away quality" items in Asia. So they learn the techniques required to replace latest technology components using preferably the cheapest tools available.

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Online Psi

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Re: Replacing BGA by milling it down?
« Reply #10 on: December 26, 2014, 01:34:43 am »
Yes, that BGA chip is underfilled with epoxy and can not be removed by simply heating it.

I thought it might be a stacked BGA and he was removing only the top IC.
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Offline Shock

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Re: Replacing BGA by milling it down?
« Reply #11 on: December 26, 2014, 02:22:45 am »
I think on the whiteboard He was just explaining rails for powering the chip and continuity testing. Looks like He has two boards with the same fault so would make sense to compare them.
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Offline jaxbird

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Re: Replacing BGA by milling it down?
« Reply #12 on: December 26, 2014, 02:30:21 am »
Yes, that BGA chip is underfilled with epoxy and can not be removed by simply heating it.

I thought it might be a stacked BGA and he was removing only the top IC.

Isn't that only used for memory, just like the good old piggy back ram/rom?




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Offline jaxbird

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Re: Replacing BGA by milling it down?
« Reply #13 on: December 26, 2014, 02:41:37 am »
Anyway, clearly you need a proper multimeter to fix an iPhone5, a shitty fluke or agilent just isn't good enough.



Edit: Merry Christmas to everyone :)

« Last Edit: December 26, 2014, 03:11:47 am by jaxbird »
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Offline atferrari

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Re: Replacing BGA by milling it down?
« Reply #14 on: December 26, 2014, 11:37:47 am »
My question: what they show in the video is the IC progressively  "destroyed" (milled down) to the BGA level or actually, to the pads level?  :phew:
Agustín Tomás
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Offline mrflibble

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Re: Replacing BGA by milling it down?
« Reply #15 on: December 26, 2014, 11:44:33 am »
Looks like they milled it down to the pads level. After milling it down he spent a good bit of time cleaning it up by applying a bit of solder, then remove again and cleanup (presumably with some solvent).
 

Offline atferrari

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Re: Replacing BGA by milling it down?
« Reply #16 on: December 26, 2014, 01:36:02 pm »
Looks like they milled it down to the pads level. After milling it down he spent a good bit of time cleaning it up by applying a bit of solder, then remove again and cleanup (presumably with some solvent).

Brute force approach, isn't it? Of course not many (any?) options otherwise.

Probably that is what he is talking about when he draw kind of an arc, marking two points on it. The area of contact, I asume.
Agustín Tomás
In theory, there is no difference between theory and practice. In practice, however, there is.
 

Offline poorchava

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Re: Replacing BGA by milling it down?
« Reply #17 on: December 27, 2014, 12:25:02 am »
Underfilled BGA is a total bitch to remove. I think unless you have a lot of time and a specialized solvent for the exact type of underfill that was used, the only option is to mill (or otherwise remove mechanically) the chip (is board is to be saved) or the board (if the chip is to be intact).

I remember that a company where I once worked had to to a post mortem memory read out from a chip that was underfilled and soldered on a metal core pcb. IIRC in the end they gave it to some technical unversity in Germany and the board was milled away after several failed attempts to dissolve the underfill. The chip was then reballed and soldered onto a breakout board.
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Offline pickle9000

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Re: Replacing BGA by milling it down?
« Reply #18 on: December 27, 2014, 01:28:00 am »
Just a few observations.

- fixture to hold the board and many others, so more than a one off.
- anti-static blue towel
- real scalpel
- awesome meter
- I'm sure he's better at fixing phones than any one in my neighborhood.
- hot air handle is used, really used, really really used.

A guy that goes to work fixes a phones for a living. He's got my respect.
 

Offline poorchava

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Re: Replacing BGA by milling it down?
« Reply #19 on: December 27, 2014, 03:22:31 am »
Actually using a scalpel is a good choice. I also use a standard medical scalpels, number 11 blade for number 3 handle (the smaller one) and number 18 blade for the number 4 handle (bigger one). Surgical stuff is very high quality, not expensive at all (nr4 handle is like 2€ and blades are 5-7€ for box of 100) and "holy shit" is the only thing that can describe how sharp those things are. It's much better and cheaper than DIY grade exacto knives which are usually total shit.

The fixtures he uses look quite adjustable. They do look like custom made, but I think they are general purpose PCB holders.

What makes me wonder is, that it takes surprisingly short time to heat up the board with the hot air (aside from the fact the videos are sped up). I bet there are huge ground planes in those boards. I mean I could swear that the traces will lift up on some of his videos.
I love the smell of FR4 in the morning!
 

Offline pickle9000

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Re: Replacing BGA by milling it down?
« Reply #20 on: December 27, 2014, 03:36:35 am »
I used medical scalpels as well. They really are the best.

He must be using some sort of preheater (off screen). I just can't imagine even a blow torch heating up a chip that fast. He does hold the board delicately so my guess would be that he keeps his boards on a preheater.

The blue anti-static towel actually appears to be anti-static blue-jean pant leg.

Even though I am being a bit cynical I really do respect the skills, seriously good abilities.
 

Offline SeanB

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Re: Replacing BGA by milling it down?
« Reply #21 on: December 27, 2014, 05:28:18 am »
Blue jeans pant leg, well used. The jig is a milled fixture that fits a few iPhone models, you can see the hold down areas for 4, 4s in the unused half. The jeans material is actually a good thing to use for soldering, as you clean the irin tip quite well just by wiping against the material. Even works while wearing them for a quick wipe, though you really should not do it if you are wearing shorts instead of jeans. I have often done soldering with a board balanced on my knee and being held by the other leg. Wipe iron on pant leg, tin and solder fast before flux is cooked off.
 

Offline crystal

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Re: Replacing BGA by milling it down?
« Reply #22 on: December 27, 2014, 02:21:18 pm »
This is the best electroniker ever. Amazing skills really, Pro'sKit analog multimeters would now become the reall stars  :-+
 


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