LCD TV BGA replacement, can I do it?

[Jan Catrysse]

Hello,

I am repairing the LG LCD television for my ex-wife and I need to replace the mainboard's 633-pin PBGA chip (FLI10610H). I never did this before, and I can't seem to find some rock-solid advice on how to do it correctly.
Could I ask some beginners advice?

I have an Aoyue 863 pre-heater and I am using my Quick 861 hot air station. I first tried removing the chip and putting it back on, just with some leaded solder on both the IC and the pads on the board, that didn’t seem to be a good idea… I think I fried the damn thing. But it really seems to stick

I now ordered a few new IC’s and some re-balling stuff from Ali Express like: a jig, stencils, solder balls, etc. But I am not sure on how to proceed with the tools I have. I might invest in some cool new gear for my man-cave (just nice to have / any advice on a <2K rework station? JOVY RE-8500 or RE-7550?), but maybe I should just use the tools I have, will that suffice? I don’t want to do a crappie job.

1.   I think I fried the existing BGA. What is a reasonable temperature for the pre-heater and hot air station to avoid frying things? My pre-heater was set to 300C (no profile used) and I rose the hot air temperature to 400C to remove the BGA (unleaded). That killed it, I think. What profile should I use for the bottom heater and what hot air temperature range (leaded balls)?

2.   I suppose the new BGA will be delivered without solder balls on it. I was wondering if I can solder the balls on it with hot air, won’t all the ball fall off or fly away? Is this a possible choice or do I need to buy like an IR soldering station (Ali Express: PUHUI T835T-835 or is that a piece of crap?) or a re-flow oven? (Ali Express: T-962)
On most video’s I watched they all use the IR upper heater from the IR rework station, something I don’t have for the moment.

3.   Will these balls melt on the BGA pads completely or do I just need to make them stick a little bit without deforming them? I don’t even know if this is possible, but it isn’t clear for me on the video’s on YouTube.

4.   Can I use any size of solder balls that seem to be the same size as the pads? Or do I need to use bigger / smaller balls?


Thank you! Appreciate any advice.

[goaty]

You can´t do it. You need something like a Zhuomao BGA Rework Station.
Or maby, but only if you´re very very lucky.

[Jan Catrysse]

Aha... just another reason to buy some neat stuff ;-)

Could someone just tell me what would be a good bang for the bucks rework station? I see dozens of Chinese and other rework stations ranging from 500 to 2000 euro's and I don't mind spending some money if I will be happy with my choice. I don't want the top notch 10.000 euro stuff but something worth wile, nice to have for the ten years to come... if it exists of course.

I'm sick of spending 500 euro on stuff I replace 3 months afterwards for the "expensive" equipment I didn't know I needed the first time.

Thanks

[senso]

I worked a couple years with an Ersa IR650A, it costed something to the tune of 150k €, but it sure was nice to use, I never ever used the pre-heater above 120ºC, anything above that would only lead into lifted pads, but I gave all boards a nice 3 minutes at 120ºC(plus slow ramp of 5-10 minutes depending on the board size), replaced lots of GPU's and played around upgrading soldered CPUs and it never damaged anything unless I done dumb things like setting it to 400ºC that would end with an exploded die or charred PCB..

[thinkfat]

I have the impression that this job will require tools you'll never need again for an amount of money it will make you cry.
All for a lost cause. Because having the tools doesn't mean you'll be able to do anything useful with them.

[Jan Catrysse]

Thank you all… I will give it a try without a BGA rework station. Thumbs up.

[thinkfat]

Thank you all… I will give it a try without a BGA rework station. Thumbs up.

 

I mean, what's the worst that can happen? It's not likely she'll get a divorce if you botch it.

[Jan Catrysse]

The worst is getting back :-)

[aqibi2000]

Just replace the board

Or send me it to reball, got a BGA rework station (UK only)

[Jan Catrysse]

Or send me it to reball, got a BGA rework station

Thanks for the offer! I'll give it a try with the 3 IC's I ordered

[Rasz]

do not try your very first time on the thing you want to fix  , you need to train on some sacrificial gear, laptops pulled out of garbage/recycle bin are a good start

I think I fried the damn thing.
I think I fried the existing BGA.
That killed it, I think.

define fried? did it bulge? did the pcb popcorn?

but maybe I should just use the tools I have, will that suffice?

its possible for an experienced person to do it effortlessly with just preheater and hotair ... after about half a year of doing it every day ;-)

My pre-heater was set to 300C

doesnt matter what it was set for, what matters is the temperature of the piece on it
100-170C depending on pcb and melting point of plastic parts, preheater is not for melting solder

and I rose the hot air temperature to 400C to remove the BGA (unleaded)
What profile should I use for the bottom heater and what hot air temperature range (leaded balls)?

again - doesnt matter what it was set for, what matters is the temperature of the piece you are working on
hotair is not a laser gun, what you get on your work piece depends on the airspeed, nozzle size/shape, distance, angle, ambient temperature etc.
Even moisture level of environment your hardware was stored in! this is how you can get popcorn if you dont bake you chip straight from china before soldering
You learn to estimate all of it with experience

On most video’s I watched they all use the IR upper heater from the IR rework station, something I don’t have for the moment.

because thats the fast and repeatable way of doing it, almost set and forget

3.   Will these balls melt on the BGA pads completely or do I just need to make them stick a little bit without deforming them? I don’t even know if this is possible, but it isn’t clear for me on the video’s on YouTube.

https://www.youtube.com/user/1servicecore/videos
should have good videos showing what happens to the balls

you dont want to heat BGA chips above 250C for long periods, you also dont want to blast them with high temp for short periods its all a balancing act. For replacing big chips with hotair you will need some kind of stand to hang it above the work piece

consider a good hot air station, like a Metcal HCT2-1000

he already has a very good hotair, 4x more powerful than this metcal

[Jan Catrysse]

Thank you @Rasz!!

Fried?
I did not have visual damage on the IC, no bulging or delamination. But the IC stayed cold when I applied power to the mainboard and the current consumption on my power supply was only 500mA and before it was 950mA. The IC was getting warm before I removed it.
To put it back I cleaned and tinned all the pads on both the IC and the mainboard. I am not sure if all pads are connected, as I did not use solder balls.

Temperature:
The mainboard upper temp from the pre-heater was about 183C so I will lower that and I will use a profile to get it slowly up to temp. I could not see or measure damaged parts (other than the IC) on the mainboard upper or lower side.

Video:
Nice Youtube channel! I don't speak Russian but nice footage, very interesting!

I will give it a new shot when the solder balls, stencils and IC's arrive. I'll let you know how it works out.

Thank you!

[goaty]

To put it back I cleaned and tinned all the pads on both the IC and the mainboard. I am not sure if all pads are connected, as I did not use solder balls.

Then what was happening is a) the chips was not connected at all or b) you shorted out many pads possibly damaging the circuit behind it.
The solder balls _are_ the connection. No point without them.

[shakalnokturn]

If you don't practice on less important equipment first, the chances you'll kill your PCB in attempts are high, even using decent tools...
I don't think BGA can be done without failing a number of times to learn.

[brabus]

We all would love to see some photos.

[Jan Catrysse]

We all would love to see some photos.

No problem, will do.

I am getting nervous now 

[goaty]

But then I have the deepest respect for positive thinkers. I´d never even start working on that.

[Jan Catrysse]

But then I have the deepest respect for positive thinkers. I´d never even start working on that.

Well... it is for my ex-wife... you understand the pressure? 

No, seriously... it's just a little experiment... never did a BGA before and I was telling my kids "yeah no problem... daddy can fix that television... no problem at all!"

My big mouth is biting me in the ass now, isn't it 

[Jan Catrysse]

 

Some pictures, removing the (already badly replaced) BGA. Some pads ripped of... one I tried fixing already... I will fix the others when my BGA jig arrives. Some are not that important I think, nc's or for the PCMCIA connector, others are.

[Jan Catrysse]

I didn't know new chips came preballed… to bad I ordered all that reballing stuff… but it sure was more easy. Although leaded solder tends to be more forgiving.

I managed to put in the chip and I presume it is working because it draws power, gets hot and my toslink is working, but still no PWM video signal. Same problem as the original chip I pulled off.

I assume something else is broken but I'm out of clues…

[Rasz]

what made you think in the first place that main IC was broken?

[james_s]

Yes new ICs always come ready to install, re-balling is as the name implies for rework, otherwise it would probably be called balling.

In my experience it's natural to suspect the big, complicated, difficult to test parts but the actual fault usually turns out to be something simple.

At this point I'd say your best bet is to cut your losses and find a working board on ebay, there are lots of boards out there from TVs with cracked panels, whether there's one for your particular model is a crapshoot but the times I've needed one I've always found one. You could keep troubleshooting this one but you already damaged some of the pads so it's not really worth messing with at this point.

[Rasz]

At this point I'd say your best bet is to cut your losses and find a working board on ebay

but what if its the panel? or backlight supply :=) OP didnt mention any diagnostics making us all think bad mainboard was a foregone conclusion

[taligentx]

(If you're reworking BGAs professionally, skip this post or be prepared to cringe).

Unfortunately the ripped pads make it far more difficult - in this particular case, replacing the main board is the most likely solution.  For the record, though, it is possible to remove, reball, and reinstall BGAs successfully as a hobbyist without a rework station if you understand how a rework station operates, take a look at various rework temperature/time profiles, and emulate these profiles closely.  This applies at least for the typical TV BGAs that have larger pads than CPUs, GPUs, etc.

I started off the same way by picking up a free TV where the most common fault was cracked BGA solder joints - this was confirmed as the TV successfully powered up after heating up the chip with a bit of flux  (LG TVs between 2009-2016 or so seem especially prone to BGA issues).  As I had no interest in picking up a rework station for the infrequent use, I played around with a few old motherboards to dial in a barebones BGA replacement process that I've used on 7 boards so far over the past two years, with 1 failure (a newer Vizio 4K with dual BGAs and small pads/high pad count).  The rest are still working in normal daily use (friends, family, etc) - replacing the original lead-free solder with leaded solder balls may be helping with this longevity.

Disclaimers - this assumes that you don't mind a time/labor intensive process, the only alternative is recycling the PCB, and you don't need to guarantee long term survival (as in, you're not selling the device, selling a repair service, etc).

My minimal equipment (~$80USD): hot air (calibrated 858D), preheater (large kitchen griddle), thermocouple with exposed bead, kapton/foil tape, paste flux, chip removal suction pen, BGA stencil set (generic kits with an assortment of pad sizes work fine), lead solder ball kit, desoldering wick/braid.

Moisture removal: place board in a 110c heated chamber (toaster oven used only for electronics) for 24 hours.

BGA removal:

• Use kapton/foil tape around BGA to protect nearby components
• Set thermocouple touching BGA and PCB
• Preheat PCB to 150c.  I use a large griddle with the PCB suspended by the edges on metal rails - it helps to cover everything except the area around the BGA with aluminum foil to get up to temperature.
• Setup hot air: nozzle removed, max air speed, 350c.  This is a high temperature but I keep the nozzle far from the BGA and use distance to control the chip temperature.
• Add paste flux around BGA
• Heat at a distance to 160c
• Ramp from 160c to 190c over 120s
• Ramp to 220c for 60s with peak at 240c for 5s
• Nudge BGA to verify solder is molten - the chip should move freely
• Remove BGA by suction pen

Solder removal:

• Add paste flux to entire BGA and PCB surface
• Set soldering iron to 325c
• Add lead solder to tip to form large ball, drag the ball across the BGA and PCB surface to replace the lead-free solder - this is done without letting the soldering iron tip touch the PCB or BGA.
• Repeat with fresh ball of lead solder
• Add paste flux and use wick to remove solder until completely flat - it's very easy to rip pads if you apply any downward pressure to the wick.  The wick should float on flux as you move it around the PCB and BGA.

Reballing (also done on new BGAs to remove lead-free solder with leaded solder):

• Use stencils to determine size of solder balls by overlaying different solder ball size stencils on the BGA to find a match
• Spread paste flux in a layer as thin as possible on BGA - excess flux will cause solder balls to float during heating
• Place solder balls - typically you should use a matching stencil and a jig but I've found dealing with stencils and jigs to be a pain and usually don't have an exactly matching stencil so I just go into zen mode with a magnifier and place the solder balls manually (takes 30min or so).
• Place thermocouple on side of BGA
• Set hot air station to 350c, air speed 1
• Hold hot air nozzle at a distance, heat at 1.5c/s to 150c
• Ramp from 150 to 170c for 120s
• Bring nozzle closer to raise to 215c and hold for 45s - all solder balls should melt and align to the solder pads
• Reduce hot air temp, increase air speed to max to cool the BGA rapidly
• Clean flux residue

Installation

• Add thin layer of paste flux on PCB
• Add BGA to PCB
• Set thermocouple to touch PCB
• Heat PCB to 150c
• Set thermocouple to gently touch BGA - too much pressure from the probe could shift the BGA.
• Set hot air to 350c, air speed 5
• Heat at a distance to 150c
• Ramp from 150c to 170c for 120s
• Heat to 215c and hold for 45s
• Turn off preheater and hot air and rapidly cool BGA and PCB

I was pleasantly surprised/shocked when the first board worked after this process and have had decent results since - I'm sure I'll run into more failures in the future, but there are zero stakes with the projects I take on so it's not an issue.  Anyone that needs reliably repeatable results should absolutely pick up a rework station - but if you're just playing around with personal projects, BGA isn't necessarily a no-go zone for hobbyists.  Good luck!

Edit: Clarified that the chip temp is controlled by hot air nozzle distance.

[aqibi2000]

Built several BGA rework stations and I would recommend you purchase a PC410 PID controller which has the ability to create a proper reflow profile (temperature control, temperature ramp and dwell setting) in order  to control the output heating element load of choice alongside a K type thermocouple positioned 1mm next to the IC of interest. A PC410 PID controller can be used for the preheater of which I have benchmarked against my Jovy RE-8500 rework station.


Furthermore the ripped pads can be easily rebuilt, by the use of single strand copper wire taken from anywhere (even desoldering braid) and the use of UV curing pcb resist to position the wire which is coiled up with tweezers acting as a pad (done this successfully for 0.6mm, 0.5mm, 0.4mm and 0.35mm BGA chipsets).

FLI10610H Looks like an easy 0.6mm job like the southbridge chipsets used on some historic laptops