Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Equipment Usage, Soldering, Techniques, and Reviews
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 10-14-2021, 03:59 AM   #1
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Post BGA reballing techniques and equipment

I work mainly with larger (2000-3000 ball) BGA chips, typically 0.4-0.55mm solder balls. I've reballed many of these, and it's always a royal PITA. My current system is direct heat stencils and hot air, which works but is very tedious. Typically takes me 3 hours, which is about 2 hours too many. And to make matters worse, today i discovered that one stencil must be warped, because as soon as I apply heat, 1/3 of the stencil lifts away from the chip and all the solder balls run together. Unfortunately that's the only stencil I have in that size, atm. You know... we've all had weeks like that.

So, what materials, stencils, flux, techniques, tricks, etc. do you guys use? There's gotta be better ways to do things. Please don't just be all grandiose and vague ("Use better stencils!" without specifying exactly which stencils are 'better' in your opinion, etc.). If you have something that works, I'd like enough information so that I can go buy it myself.
Joe24 is offline   Reply With Quote
Old 10-14-2021, 04:09 AM   #2
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

You need to identify where the time is going.
I use Amtech 559 flux and indirect heat stencils in a holder.
diif is offline   Reply With Quote
Old 10-15-2021, 12:48 AM   #3
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Time goes to initial cleanup, solder ball placement, inspection, and patching defects. 559 flux holds the balls in place? I've never used indirect stencils, don't know much about them.
Joe24 is offline   Reply With Quote
Old 10-15-2021, 01:38 AM   #4
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

Clean up is quick, a large blob of leaded solder followed by some Chemtronics braid, done just after the chip has been removed whilst there is still some heat in the board.
Placing the balls and ensuring only one is in each hole is the most time consuming part. I tip some balls into the stencil holder and tilt it so they fill all the holes, then tip out the excess.
Yes, 559 holds the balls in place, the lightest of smears is required.
diif is offline   Reply With Quote
Old 10-15-2021, 09:26 AM   #5
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Sounds faster than what I'm doing. I dump a bunch of solder balls on top and chase them around with a Q-tip. Direct heat stencils don't have a stencil holder around them to stop the loose balls from leaving town. 559 must be better at keeping stuff in place than what I'm using. Flux I'm currently using is some ChipQuick water-wash stuff, which is okay for some things, but yeah the balls would run all over the place if I removed the stencil like your method.
Joe24 is offline   Reply With Quote
Old 10-15-2021, 09:53 AM   #6
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

You could make a little wall around the stencil with some plasticine/modelling clay/blu tac to stop them rolling away.
diif is offline   Reply With Quote
Old 11-01-2021, 03:18 PM   #7
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Can't buy Amtech flux in my country. Seems to be a US-only thing. There are all kinds of Chinese fakes available, but the real thing doesn't seem to be available.
Joe24 is offline   Reply With Quote
Old 11-01-2021, 05:19 PM   #8
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

Yes, there are plenty of fakes but it's not just a US thing. I bought mine in the UK off Ebay.
diif is offline   Reply With Quote
Old 11-02-2021, 12:15 AM   #9
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Just because it says Amtech... if you got yours from eBay, I'm almost certain that you're not using genuine Amtech.

Anyhoo, Amtech themselves will sell to my country from their website amtechdirect.com, so we'll give 559-ASM and 213 fluxes a go.

I've since been reamed out by multiple people for using water-wash flux for reballing. I didn't find it very good anyway, turns real watery and runny when it gets hot, beads up like water does, which is why the stencil needs to stay in place until the balls are fused. But they also say the residue from water-wash flux is a problem. Even though the stuff I'm using (ChipQuik SMD4300TF30) says no-clean and I don't use more than a thin smear, the fact that it's water wash apparently means there are some nasty corrosive detergents left under the chips. And it's also hygroscopic as hell, which doesn't help the corrosion issue. I know from experience that it's a pain to clean up with Q-tips/IPA99, seems like you can never get it all. And after a couple heat cycles, more residue spreads out from under the chips....

Last edited by Joe24; 11-02-2021 at 12:20 AM..
Joe24 is offline   Reply With Quote
Old 11-02-2021, 01:44 AM   #10
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

Its says Amtech and it is genuine Amtech.
diif is offline   Reply With Quote
Old 03-10-2022, 05:50 PM   #11
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Well I'm trying the exact method as you've outlined, and I have yet to successfully reball a chip using the stencil holder and Amtech 559 flux (there are 2 different variants of 559, I'm using NC-559-V2-TF). Made 5 different attempts this afternoon, varying the process a bit each time. So I'm calling BS here. You must be working with larger pitch chips or something. Or are drastically misrepresenting your success rate with this method. Invariably, a bunch of solder balls run together, and I spend the next couple hours removing bridges and manually replacing solder balls in the damaged areas. Or just starting over. Tedious and frustrating, to say the least. Have tried various amounts of genuine Amtech 559 flux, down to a layer so thin that it won't even hold the solder balls in place. No joy. What are you doing different?

Last edited by Joe24; 03-10-2022 at 06:21 PM..
Joe24 is offline   Reply With Quote
Old 03-10-2022, 05:54 PM   #12
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

This is 0.45mm solder balls on 0.7mm or so pitch. Specifically, an Nvidia GP106 GPU.

Last edited by Joe24; 03-10-2022 at 05:57 PM..
Joe24 is offline   Reply With Quote
Old 03-10-2022, 06:25 PM   #13
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

Quote:
Originally Posted by Joe24 View Post
Well I'm trying the exact method as you've outlined, and I have yet to successfully reball a chip using the stencil holder and Amtech 559 flux (there are 2 different variants of 559, I'm using NC-559-V2-TF). Made 5 different attempts this afternoon, varying the process a bit each time. So I'm calling BS here. You must be working with larger pitch chips or something. Or are drastically misrepresenting your success rate with this method. Invariably, a bunch of solder balls run together, and I spend the next couple hours removing bridges and manually replacing solder balls in the damaged areas. Tedious and frustrating, to say the least. Have tried various amounts of genuine Amtech 559 flux, down to a layer so thin that it won't even hold the solder balls in place. No joy. What are you doing different?
What equipment and technique are you now using that is different from your first post ?
diif is offline   Reply With Quote
Old 03-10-2022, 06:37 PM   #14
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Was using direct heating stencils. Now trying a reballing jig that takes 90mm stencils. The kind you mentioned, with the removable top and a slide vise that holds the chip. Direct heating stencils are okay for small stuff, but once you get up to the bigger GPUs, stencil warping becomes a huge issue. Also changed to Amtech flux, which is what the internet says I should do.

Last edited by Joe24; 03-10-2022 at 06:45 PM..
Joe24 is offline   Reply With Quote
Old 03-10-2022, 06:49 PM   #15
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

The problem is that the solder balls run together after I remove the stencil, and even more so when I begin applying heat and the flux warms up and gets thinner. Probably 100-200 solder balls to replace manually every time, which is getting close to 10%.

Last edited by Joe24; 03-10-2022 at 06:54 PM..
Joe24 is offline   Reply With Quote
Old 03-10-2022, 06:53 PM   #16
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

How are you applying heat ?
diif is offline   Reply With Quote
Old 03-10-2022, 07:09 PM   #17
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Hot air soldering gun at minimum fan, with the snout removed for minimum air velocity, and a decent distance away (4"). Some balls are running together before I even start heating, so that's at best only part of the problem.
Joe24 is offline   Reply With Quote
Old 03-10-2022, 07:25 PM   #18
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

You need to use indirect heat if you're not using direct heat stencils. I place the chip on my hotplate after the balls have been placed.
Balls shouldn't be running together before you've added heat.
diif is offline   Reply With Quote
Old 03-10-2022, 07:40 PM   #19
Joe24
Member
 
Join Date: Jun 2021
City & State: Earth
My Country: Earth
I'm a: Knowledge Seeker
Posts: 37
Default Re: BGA reballing techniques and equipment

Oh I agree with you there, they really shouldn't move. Anyhoo, what type of hotplate do you mean? One of those smooth-top ones they use for removing phone screens, or the ceramic circuit board preheater style? I might give it a go in my bench oven (former toaster oven). If you're talking about the smooth-top heaters, I don't see that working on a GPU, because the die is considerably smaller than the BGA base. Especially a GP106.

Last edited by Joe24; 03-10-2022 at 07:42 PM..
Joe24 is offline   Reply With Quote
Old 03-10-2022, 07:43 PM   #20
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 6,034
Default Re: BGA reballing techniques and equipment

A Honton HT-2020.
diif is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 07:59 AM.
Did you find this forum helpful?