Daan,
If you have a spare board, try applying a spot of high temperature oil to a
bga pad with a via and heat it to soldering temperature. Any outgassing of
the via should be visually obvious.
( I am speaking here from theory, not practise, but it should work).
Regards
Eric Dawson

> -----Original Message-----
> From: d. terstegge [SMTP:[log in to unmask]]
> Sent: Tuesday, May 28, 2002 11:37 AM
> To:   [log in to unmask]
> Subject:      [TN] Anti-voiding solder paste
>
> Dear Technetters,
>
> I'm having some problems with really big voids (up to 50% of the diameter)
> in the solderjoints of BGA's. The problems occur on our only board that
> has via's in the BGA-pads. The via's are filled and plated, so from the
> outside you don't see they're there.
> I'm quite sure that it's the board that's causing the problems, but the
> boardvendor does not agree and thinks our solderpaste is causing it.
> To prove that I'm right  (or to solve the problem if the boardvendor is
> right !) I'd like to do some tests with a solderpaste that's known to
> cause a minimal amount of voiding. From earlier discussions I learned that
> such solderpastes exist.
> Does anyone have a recommendation for such a solderpaste ?
>
> Daan Terstegge
> SMT Centre
> Thales Communications
> Unclassified mail
> Personal Website: http://www.smtinfo.net
>
>

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