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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

BGA re-reflow

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BGA re-reflow | 20 December, 2011

We don’t do it often, but on a test failure, when the cost of a BGA relative to our confidence that we might have a questionable joint is high, we will flux it with a low solids no-clean flux and reflow it again.

We don’t do it often enough, and don’t have adequate subsequent debug operation traceability (though I’m working on this) to verify effectiveness, but it does work at least some of the time. I am curious as to how many other people out there are doing this and what other forum member opinions might be on this practice. Thanks in advance.

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BGA re-reflow | 21 December, 2011

Kim: We understand what you're saying.

For us, fluxing the BGA and activating the flux are the issues. * If you're squirting liquid flux under the BGA with a plastic bottle with a needle tip on it and then reflowing less than the whole board with a rework tool of some sort, don't ship any of that product to us. * If you have some way to control the flux applied and keep it from spreading to portions of the board that don't see the entire reflow activation temperature, we're OK with your approach.

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BGA re-reflow | 24 December, 2011

I've reflowed many different size BGA's in an effort to better the connection and to help the board pass functional test. Using a middle of the road liquid flux and a convection spot rework machine and almost every time I would reflow a failed board it would rectify the issue. The only times that it didn't work we would end up having to remove the bad BGA and replace it with a new part using just tacky flux, placing it on the board, and reflowing it using the same spot convection rework machine. No extra solder paste, just tacky flux and the BGA solder balls themself.

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