If grey, then in all likelihood it is spatters of reflowed paste - the grey
dots are present before your aqueous wash. Your paste app processes should
be checked or what about the oven temp profile - has this been qualified?
If black, then bigger problems persist i.e. possibly oxidised nickel, but
easily checked on bare board.
-----Original Message-----
From: Prashant Chopra [mailto:[log in to unmask]]
Sent: Tuesday, April 22, 2003 8:59 AM
To: [log in to unmask]
Subject: [TN] problem with gold pads of the pcb
hi all,
we are using gold finger pads on the pcb. but after going thru smt process
of screen printing,component insertion, reflow and aqueous wash we are
facing the problem of grey color dots on the pads.
This problem is with the pads where no components are being placed.
There is no solder paste printing on these pads nor any components are
place there and they are being covered with Kapton tape thru out the above
process.
Can anyone point to some reasons for this problem?????
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