Re: BGA's are killing my project




johnspeth@xxxxxxxxx wrote:
Hi everybody-

My project uses several BGA parts. We're in the second board rev stage
(rev 2). Our board manufacturer doesn't seem to be able to 100%
reliably solder those parts down. It makes SW debugging troublesome
because one never knows if the SW or the part is misbehaving. We've
had 15 boards built and I estimate 20% have BGA problems.

I'd like to hear other's experiences with and solutions to BGA
soldering reliability problems. I have a few questions to kick off the
discussion:

Is it a manufacturer process problem that can be totally fixed with
some soldering process improvement? (Corollar: Is my board builder not
up to the task?)

It's a testing and QC/QA issue.


Is this a natural and expected problem that I just have to live with
(result = reduced board yield)?

No. you have to help the board assembler to solve the problem.


How much does the lead-free directive contribute to the problem? (My
rev 2 boards we're built using no-lead solder but rev 1 boards were
built using leaded solder and had the same BGA problems.)

Yes, it does. Lead-free requires higher temperature and more expensive
solder (silver).


Does X-ray inspection *really* identify badly soldered parts 100% of
the time?

Yes, it should help, together with boundary scans. Are they Jtag
scanable?


What is a typical delivered board BGA solder failure rate that you guys
will accept?

Zero, they should go back to be oven.


Thanks for sharing your opinions and experiences.

JJS

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