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| Date: | Fri, 1 Nov 1996 23:43:58, -0500 |
| Content-Type: | text/plain |
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Good Day,
This is a request for some assistance on a wavesoldering
problem that we are currently experiencing on some mixed technology
boards that we process. The boards have surface mount top and bottom
and when the process is set to wave the bottom side with no defects
we are experiencing a problem with some top side surface mount IC's
de-soldering! I have tried using soldering pallets set at
approximately a 30 degree angle with some success but it slows down
the processing time and the top side components still come loose.
Initial profiling indicates that the top side of the board is showing
temperatures below the eutectic point of the solder paste being used.
When the boards are processed without the pallets the defect rate
increases dramatically but the incidence of topside component des-
soldering decreases! The wavesolder machine is a T/D Nu-Era with
dancer wave and the flux being used is Kester 2331-ZX. Topside
preheat temperatures just prior to wave entry are around 185 degrees
F.
Another question is in regard to voids and blowholes occurring
on a PTH board that is auto-inserted. Just can't seem to get rid of
them. The boards are inspected at incoming for voids in the plated
thru holes. Profiling indicates that all process parameters are
correct. Any ideas?
From: Mark A. Warycka
Process Engineering Manager
Electronic Systems, Inc.
Sioux Falls, SD
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