Andre,

I've seen opens and shorts caused by the wave solder process reflowing BGA 
solder connections.  When it happened the reaction plan was to immediately 
100% inspect paste deposition, check the reflow profile, and to 100% x-ray 
after reflow.  Because we didn't check the wave solder process, we allowed 
more defective boards to be built.

I've also been told of occurrences where there were BGA connections becoming 
open on the package (but still soldered to the pad) on non functional BGA 
I/Os.  The thought here is that the wave profile was pushing the edge and 
the joints that had no internal heat sinking were reflowing.

At any rate, an IR temp gun was purchased to monitor the topside temperature 
at wave soldering.  The target I believe is to be below 160 C.

Hope this helps.

 ----------
From: Andre Bisson
To: Technet
Subject: Wave and BGA
Date: Wednesday, July 16, 1997 10:00AM

Hello all,

I will like to have comment on any effect that a wave can do on a BGA.

We have some boards with BGA on component side and many component on the
solder
side. Our process will be reflow component side, glue solder side, install
all TH
parts and go to wave.

Is anyone had or have  problems with BGA (solder joints problem) after wave?
Our
via's are half tented with solder masks and the trace connecting the via to
the
BGA pad is approx. 0.020"-0.030".

My concerns are:

 - Re-reflow of BGA solder ball causing cold solder or any solder defect?
 - Reliability problems?
 - Etc.

Any advice will be well appreciated.

Thank you.

Andre Bisson
CAE Electronics
[log in to unmask]

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