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July 2006

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TechNet E-Mail Forum <[log in to unmask]>, sumxp <[log in to unmask]>
Date:
Wed, 26 Jul 2006 09:38:24 -0500
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We have a HASL(Sn/Pb) board(FR4) with gold finger edge that having
dewetting issue across 30% of the lands.We have done below evaluation to
find out the root cause;
1)use short,medium,long profile,increase and reduce peak temp.
2)change to different brand of solder paste.
3)clean the board with IPA.
4)Apply a layer of flux on pcb and reflow it without paste,clean the board
& follow by normal smt solder paste reflow process.
All above countermeasures couldn't solve dewetting issue.We brought in the
pcb vendor & they couldn't give any answer except coming back to us to say
that the board is nothing wrong.
Could anyone explain to me what went wrong with the board.It is a Sn/Pb
process.We are seeing dewetting even though the baord is not populated.

Thanks in advance..

rgds
sumxp

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