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BGA Failure Rate?

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Jim

#46442

BGA Failure Rate? | 3 January, 2007

Hi,

I was looking for information on failure rates for BGA components. I am analyzing our BGA rework rates and find it difficult to define a root cause when a remove and replace of the BGA component corrects the test errors. Inspection prior to rework does not indicate a process problem, but I can only inspect the outer solder connections. Can someone point me to information on how many of these test fails may be due to bad components?

Thanks

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#46443

BGA Failure Rate? | 3 January, 2007

Your failure rate should be as good or better than any other leaded part on your board. Have you done a reflow profile on this board. We typically sacrifice a board and drill a hole from the bottom and then imbed a probe under the part to get the temp inside the array as well as outside. Don't forget if your running ENIG (with non ROHS parts you need to hit 220C, if the parts are lead free much higher temps are required) If that looks good find an X-ray machine and see what is going on.

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Rob

#46444

BGA Failure Rate? | 3 January, 2007

Consider this:

The inner balls will be at a lower temperture than the outer balls in reflow, so if you cannot inpsect them then that may be where your problem lies.

Are you reworking with a specialist machine that is directing the right amount of heat right onto the BGA instead of a best fit oven profile for the entire board? If so then it may be only at rework stage where the BGA is getting the right temperature to feflow consistantly.

An Ersascope or similar is a handy low cost aid to monitor this process, as is accurate profiling such as suggested by Doug.

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#46446

BGA Failure Rate? | 3 January, 2007

What is your biggest failure mode? You root cause problem could be anything from poor ICT fixture to bad incoming inspection. Generally, BGA's are a high yield producing component. Just cause they're neat-o doesn't make em' bad.

As for 85% yield - it all depend on your product and company. Most people would poo-poo on 85%. But if each board costs pennies to make, dollars to fix, and makes you gobs of money, fixing the other 15% may not be worth it.

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