Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA Solder Mask Repair

#5335

BGA Solder Mask Repair | 22 February, 2001

I have been reballing some BGA's. Some of the BGA's have solder mask damage and cannot be recovered until I find a way to reapply the solder mask. Are there any suggestions?

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#5337

BGA Solder Mask Repair | 22 February, 2001

You're not sposed to pull the mask from the BGA when reworking it!!!! ;-)

Well, if you insist. You can be as fancy as you want. Basically, all you need to do form a dam to prevent the solder from flowing from the pad to the via and starving the solder ball when you reattach it to the board.

* Bird brain approach - slop some Tak Pak on the trace [chirp chirp]

* Fat head approach - squirt some vinyl peelable solder mask on the trace

* Propellor head approach - paint a low temperature cure version of a standard board solder mask, like Dexter Hysol recommended SE 1922 two part epoxy, as a touch up to SR1000 solder mask. SE1922 is color matched to SR1000, and is available with #20 catalyst in kit form.

* Rocket scientist approach - paint some two part epoxy packaged for board reworkers [like you]. Buy it from our old buddy Denny at http://www.circuittechctr.com/products/1151322.htm

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#5382

BGA Solder Mask Repair | 27 February, 2001

Hello Mark,

It is possible that SolderMask, Inc. could selectively remove the existing solder mask, clean and reapply a Photoimageable solder mask to the BGA area. Mostly likely the mask on your boards is a Liquid Photoimageable Solder Mask (LPISM), which is what we would also use. While we have access to all the Liquid Photoimageable Solder Masks available in the USA, it is possible that your boards may have be manufactured overseas using a solder mask that is not available in the USA. If this is the case then we would use a LPISM that best color matches your product. We have been very sucessful with this process both with populated and un-populated boards.

If you would like to contact me at 714 842-1987 I will work with you to see if our service can help.

Regards,

Frank Kurisu SolderMask, Inc.

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#5394

BGA Solder Mask Repair | 27 February, 2001

Since Mark is talking about rework, I assume his board is fairly, fully assembled. Do you have to capabilities to work in that type of environment? Or do you work with bare boards?

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#5397

BGA Solder Mask Repair | 28 February, 2001

Hello Dave,

Solder mask rework has been performed on both bare and populated boards.

There are factors that come into play with a populated board that make this type of rework more difficult, such as the density of components(especially around the BGA location), configuration of the board and topography of the component heights, to mention a few. Also with a populated board ESD controls should be in place to minimize the possiblilty of damage.

Currently we rework 4 to 10 populated boards per month of a very high relibility board. No rejections to date.

Please understand that this process is very unique and can only be evaluated in a case by case situation.

Regards,

Frank Kurisu SolderMask, Inc.

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#5443

BGA Solder Mask Repair | 2 March, 2001

Frank, I am not talking about the masking on the PCB. I am actually talking about the masking on the solder side of the BGA. We have a very very high dollar BGA and are trying to reclaim alot for reuse. When we remove the BGA from the assembly, you have to do a little cleaning up before starting the BGA Re-Balling Process. Well by just using a soft cloth the green masking gets rubbed off the bottom of the BGA. WE are trying to figure out a way we can re-apply the masking on the BGA and still leave the ball sites free so we can re-ball them. Do you have this capability or know of a kit or process that do this ?????

Thanks,

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#5447

BGA Solder Mask Repair | 2 March, 2001

Hello Mark,

To date all solder mask rework we have done has been on the PCB board.

I believe that it possible to reapply solder mask on to the ball side of the BGA. Would it possible to evaluate some of your BGA's?

You can contact me at 714 842-1987

Regards,

Frank Kurisu

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