Lum,

We have used 1B31 for years and have not seen the problem you are
presenting. We spray our 1B31 conformal coating.  I have looked at hundreds
of x-rays and am interested in seeing pictures of this phenomenon. Even with
brushing, I doubt that you are getting c/c material actually on the solder
balls locate under the package.

joe

-----Original Message-----
From: Lum Wee Mei [mailto:[log in to unmask]]
Sent: Monday, March 22, 2004 4:27 PM
To: [log in to unmask]
Subject: [TN] acyrlic coating deformed BGA balls


Hello,

My colleague coated several test boards using 1B31 through brushing that
have BGAs moutned on them. When he took some X-rays on them, he found
many balls are deformed with what he termed as "cauliflowers" like
patterns on the balls. He attributed the casue to the CTE difference of
the acrylic coating. Is that possible?

I will try to get the X-rays from him and post it to steve so that you
experts out there can provide a second opinion on this "cute"
observation. Meanwhile, hope some of you can share your experience with
BGAs and 1B31 coating.

Thanks and regards,
Wee Mei

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