Hi Technetters, I'm back again, two months (has it been that long???) into Y2K.

My problem is on a subject about which I know little, and I write to you on behalf
of a friend upon whose project the following has manifested itself.

We have a line upon which we manufacture simple through-hole PCBs. We are using
externally supplied multi-layer boards with nothing high-density or high tech about
them. They come in looking nice and well tinned. For about six months they have
been flowing OK, with only one problem - a large ground plane caused a few problems
in one area for a little while and we had to re-adjust the profile on the flow
machine (this is, I am sure, irrelevent to the problem). We like to manufacture to
a very high standard, so it was concerning when some PCBs recently exhibited bare
copper in various places. We use a low tack professional masking tape to mask two
planes on the board during conformal coat - on removal, the tinning came away,
exposing bare copper! Even more seriously, at many places solder had not fully
wicked to the top of the through-hole, meaning very suspect joints. In various
places, solder had wicked away from pads, again exposing copper.

Is it possible that we are doing something wrong without realising, or shoud we be
chatting to our board suppliers?
What do you folks feel is the problem, and what do you recommend we look at?

Regards,

Richard Tilbrook
Junior Engineer

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