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BGA's - Re-ball

J.J. Thomas

#11480

BGA's - Re-ball | 13 May, 1999

What is the best way to re-ball a BGA? Who has the best system for doing it?

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#11481

Re: BGA's - Re-ball | 13 May, 1999

| What is the best way to re-ball a BGA? Who has the best system for doing it? |

Hello J.J.

The easiest and best way I've found to Re-ball BGA's is from a company called Winslow Automation. They make what they call "Solderquik" BGA preforms...couldn't be simpler!

Click on the link below and check their page out...

-Steve Gregory-

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Tony

#11482

Re: BGA's - Re-ball | 13 May, 1999

| What is the best way to re-ball a BGA? Who has the best system for doing it? | J.J, BEAM ON technology is the stencil house that has a unique unit that uses stencils to re-ball BGA's, their # is (408) 982-0164. I-Source Technical Services is another stencil house that has something similar, their # is (949)453-1500 ask for MICK.

Good luck..

Tony

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J.J. Thomas

#11483

Re: BGA's - Re-ball | 13 May, 1999

| | What is the best way to re-ball a BGA? Who has the best system for doing it? | | | | Hello J.J. | | The easiest and best way I've found to Re-ball BGA's is from a company called Winslow Automation. They make what they call "Solderquik" BGA preforms...couldn't be simpler! | | Click on the link below and check their page out... | | -Steve Gregory- | | Thanks for the feedback.

J.J.

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Earl Moon

#11484

Re: BGA's - Re-ball | 14 May, 1999

| What is the best way to re-ball a BGA? Who has the best system for doing it? | I'm using our SRT rework stuff to reball in house - when necessary. Of course, we only do this for protos and test boards. We use a standard micro-stencil, after cleaning the BGA site, and apply solder paste, then reflow in batch on the BTU's. We do have a proprietary stencil, but it's just thichker than standard. Geez, hope I didn't give away a big secret. Also, we don't use square anything apertures. Just thought I'd throw that in.

Moonman

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ScottM

#11485

Re: BGA's - Re-ball -- How thick? | 18 May, 1999

| | What is the best way to re-ball a BGA? Who has the best system for doing it? | | | I'm using our SRT rework stuff to reball in house - when necessary. Of course, we only do this for protos and test boards. We use a standard micro-stencil, after cleaning the BGA site, and apply solder paste, then reflow in batch on the BTU's. We do have a proprietary stencil, but it's just thichker than standard. Geez, hope I didn't give away a big secret. Also, we don't use square anything apertures. Just thought I'd throw that in. | | Moonman | I've heard of using the stencils for re-balling and my micro-stencil source says that a 12-mil stencil will work. Is this close to your thickness? Also, how high are the balls after reflow? Using my 6-mil stencil I was able to get the balls only 10-mils high but very consistent...

I've got a customer who showed up yesterday to pull off a 256 pin BGA and resolder it on the backside vias (he got the pattern backwards during design) -- sigh... Just two protos before he respins the design but I'm just a BIT goosy on this; vias, BGAs, reballing sounds like a recipe for disaster.

Comments?

Oh, I don't use round anything apatures - just a quirk of mine...

Cheers, Scott

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Tony

#11486

Re: BGA's - Re-ball -- How thick? | 18 May, 1999

| | | What is the best way to re-ball a BGA? Who has the best system for doing it? | | | | | I'm using our SRT rework stuff to reball in house - when necessary. Of course, we only do this for protos and test boards. We use a standard micro-stencil, after cleaning the BGA site, and apply solder paste, then reflow in batch on the BTU's. We do have a proprietary stencil, but it's just thichker than standard. Geez, hope I didn't give away a big secret. Also, we don't use square anything apertures. Just thought I'd throw that in. | | | | Moonman | | | I've heard of using the stencils for re-balling and my micro-stencil source says that a 12-mil stencil will work. Is this close to your thickness? Also, how high are the balls after reflow? Using my 6-mil stencil I was able to get the balls only 10-mils high but very consistent... | | I've got a customer who showed up yesterday to pull off a 256 pin BGA and resolder it on the backside vias (he got the pattern backwards during design) -- sigh... Just two protos before he respins the design but I'm just a BIT goosy on this; vias, BGAs, reballing sounds like a recipe for disaster. | | Comments? | | Oh, I don't use round anything apatures - just a quirk of mine... | | Cheers, | Scott | Scott, I had three different customers that made the same mistake ( pattern backwards during design). One of them actually did not read the small letters on the component specs where it says BOTTOM VIEW, believe it or not but it keep happening. Anyways, you must end up with a 25-30mil balls when screen printing solder paste on your BGA component. Also I would recomend once removing the BGA from the boards, to cover vias with solder mask on the opposite side. This will ovoid for any solder migrating down to the VIA's. Also make sure to preheat your board since it will cause your BGA to colapse un-even. I have done the most amazing re-work on BGA's. BGA's ain't nothing THE AIN'T intimidated.

Good luck...

Tony

reply »

ScottM

#11487

Re: BGA's - Re-ball -- How thick? | 18 May, 1999

| | | | What is the best way to re-ball a BGA? Who has the best system for doing it? | | | | | | | I'm using our SRT rework stuff to reball in house - when necessary. Of course, we only do this for protos and test boards. We use a standard micro-stencil, after cleaning the BGA site, and apply solder paste, then reflow in batch on the BTU's. We do have a proprietary stencil, but it's just thichker than standard. Geez, hope I didn't give away a big secret. Also, we don't use square anything apertures. Just thought I'd throw that in. | | | | | | Moonman | | | | | I've heard of using the stencils for re-balling and my micro-stencil source says that a 12-mil stencil will work. Is this close to your thickness? Also, how high are the balls after reflow? Using my 6-mil stencil I was able to get the balls only 10-mils high but very consistent... | | | | I've got a customer who showed up yesterday to pull off a 256 pin BGA and resolder it on the backside vias (he got the pattern backwards during design) -- sigh... Just two protos before he respins the design but I'm just a BIT goosy on this; vias, BGAs, reballing sounds like a recipe for disaster. | | | | Comments? | | | | Oh, I don't use round anything apatures - just a quirk of mine... | | | | Cheers, | | Scott | | | Scott, | I had three different customers that made the same mistake ( pattern backwards during design). One of them actually did not read the small letters on the component specs where it says BOTTOM VIEW, believe it or not but it keep happening. Anyways, you must end up with a 25-30mil balls when screen printing solder paste on your BGA component. Also I would recomend once removing the BGA from the boards, to cover vias with solder mask on the opposite side. This will ovoid for any solder migrating down to the VIA's. Also make sure to preheat your board since it will cause your BGA to colapse un-even. I have done the most amazing re-work on BGA's. BGA's ain't nothing THE AIN'T intimidated. | | Good luck... | | Tony | Wow, 25-30 mills can't be covered with a 12 mil stencil. Sounds like a 24 mil stencil is needed with larger apatures, I need to have a talk with my micro-stencil supplier. Let's see - need to do a little math...

Yes, I've already covered the vias - twice (the first coat was too thin) and have dressed the vias, they actually look like pads. Good news is the customer is sending me new BGAs; I stressed that this would be good because 1) you don't know what may have happened to the BGA when it was powered up, 2) the BGA would be going through several more heat excursions (???), and 3) reballing would take some time - which they don't have. So I'm on hold. I'll be using my PACE so I have the bottom side preheat.

I'm amazed at the defects that show up during design. Last week I had a customer walk in and ask me to attach three wires to the BGA pads that were omitted during the design. Two balls I was able to pick up from the BGA platform traces and the third was stop drilled from the bottom (the x-ray showed no traces in the way). It worked, the customer walked away with four working boards to finish some R&D before he respins the layout. And this was from a big, well known company! Oh well... I'm sure there are more people out there that have a few experiences as well!

Thanks, Scott

reply »

Tony

#11488

Re: BGA's - Re-ball -- How thick? | 18 May, 1999

| | | | | What is the best way to re-ball a BGA? Who has the best system for doing it? | | | | | | | | | I'm using our SRT rework stuff to reball in house - when necessary. Of course, we only do this for protos and test boards. We use a standard micro-stencil, after cleaning the BGA site, and apply solder paste, then reflow in batch on the BTU's. We do have a proprietary stencil, but it's just thichker than standard. Geez, hope I didn't give away a big secret. Also, we don't use square anything apertures. Just thought I'd throw that in. | | | | | | | | Moonman | | | | | | | I've heard of using the stencils for re-balling and my micro-stencil source says that a 12-mil stencil will work. Is this close to your thickness? Also, how high are the balls after reflow? Using my 6-mil stencil I was able to get the balls only 10-mils high but very consistent... | | | | | | I've got a customer who showed up yesterday to pull off a 256 pin BGA and resolder it on the backside vias (he got the pattern backwards during design) -- sigh... Just two protos before he respins the design but I'm just a BIT goosy on this; vias, BGAs, reballing sounds like a recipe for disaster. | | | | | | Comments? | | | | | | Oh, I don't use round anything apatures - just a quirk of mine... | | | | | | Cheers, | | | Scott | | | | | Scott, | | I had three different customers that made the same mistake ( pattern backwards during design). One of them actually did not read the small letters on the component specs where it says BOTTOM VIEW, believe it or not but it keep happening. Anyways, you must end up with a 25-30mil balls when screen printing solder paste on your BGA component. Also I would recomend once removing the BGA from the boards, to cover vias with solder mask on the opposite side. This will ovoid for any solder migrating down to the VIA's. Also make sure to preheat your board since it will cause your BGA to colapse un-even. I have done the most amazing re-work on BGA's. BGA's ain't nothing THE AIN'T intimidated. | | | | Good luck... | | | | Tony | | | Wow, 25-30 mills can't be covered with a 12 mil stencil. Sounds like a 24 mil stencil is needed with larger apatures, I need to have a talk with my micro-stencil supplier. Let's see - need to do a little math... | | Yes, I've already covered the vias - twice (the first coat was too thin) and have dressed the vias, they actually look like pads. Good news is the customer is sending me new BGAs; I stressed that this would be good because 1) you don't know what may have happened to the BGA when it was powered up, 2) the BGA would be going through several more heat excursions (???), and 3) reballing would take some time - which they don't have. So I'm on hold. I'll be using my PACE so I have the bottom side preheat. | | I'm amazed at the defects that show up during design. Last week I had a customer walk in and ask me to attach three wires to the BGA pads that were omitted during the design. Two balls I was able to pick up from the BGA platform traces and the third was stop drilled from the bottom (the x-ray showed no traces in the way). It worked, the customer walked away with four working boards to finish some R&D before he respins the layout. And this was from a big, well known company! Oh well... I'm sure there are more people out there that have a few experiences as well! | | Thanks, | Scott | Here is a few more BGA experiences...

1. REMOVE BGA, reball BGA, remove a ball from the BGA and replace it with a 30awg wire and protected using hi-temp solder and adhessive. Drill the pad all the way through the PWB, screen print solder paste using micro-stencil and placing BGA with the 30awg wire coming through the pwb. Reflow BGA using CONCEPTRONICS Freedom 2000 rework station. Attached 30awg wire to a via on solder side. X-ray and Ship.

2.Used the actual stencil to print solder paste on top of the balls of BGA with Hi-temp solder balls because did not had a micro-stencil. WORKs EXCELLENT..

3. Re-balled BGA sockets from HI-temp to sn63 solder ball..

It is great working with BGA's...

Anyone else have more experiences that would like to share??

thanks

Tony

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Mark

#11489

Re: BGA's - Re-ball | 30 June, 1999

| What is the best way to re-ball a BGA? Who has the best system for doing it? |

To RE-Ball an IC you must re-BALL the IC! The idea of using a stencil to deposit all of the appropriate solder mass can not work.

Here is the process (minus the appropriate degas baking and inspection steps).

1 - Remove all residual solder from the IC.

2 - Stencil eutectic sn63/pb37 solder paste to the IC's pad pattern (6mils typical).

3 - Apply solder balls to each pad. Many ball diameters are available. Proper and appropriate dimensions for each ic are specified by JEDEC and other standards or specifications, but the most commonly used balls, for IC's with the common pad pitch of .050 inches, are 30mil balls. (You are not going to find a 30mil stencil anywhere)

4 - Reflow the IC.

Of course this brief process description is not laced with the 5 critically important (but obvious) degas baking and washing and inspection steps.

But, any other method is pure VOODOO.

Re-Balling is a process that deserves a process.

Your BGA's are worth a Process.

All we do is this process, and we are reasonable.

Respond, or check out www.bgabumps.com

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