RE>Wave and BGA                              7/16/97

Hi Andre,
>From our experience, we found that we have to mask the via array pattern
beneath the BGA devices prior to wave soldering.  I believe that our
assemblers use Kapton tape.  There are many solder joint problems if this
isn't done.  Our vias are also partially covered with mask, but I believe
that our vias are slightly closer to the BGA SMT pads.

We also went to a high Tg (~180C) FR4 and found a noticeable reduction in via
problems on boards that went through this process.

Best regards,
Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
[log in to unmask]

--------------------------------------
Date: 7/16/97 10:37 AM
To: Greg Bartlett
From: Andre Bisson
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
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