..Oh, some other things. I have used both MPM and DEK in the past, and these
issues rarely are printer related. A rheometric pump (or ProFlow) head can help
with these issues, but again, there are so many great pastes out there that do
not have these issues, and can probably improve your printing process, I would
lean the route of a new paste qual as opposed to spending the capital on a
closed head system, unless you are printing ultra-fine-pitch or
pin-in-paste...unless of course capital is not a concern, heh-heh.
Again, good luck!
Jeff Hempton
United Technologies Electronic Controls
______________________________ Forward Header __________________________________
Subject: [TN] MPM solder Paste dryness and cartridge dispenser
Author: [log in to unmask] at Internet
Date: 1/19/99 9:46 AM
Ladies & Gentlemen:
We are currently experiencing a problem in our MPM printing process.
Often, the solder paste gets dry and leads to product defects. As a
result, operators dispose the "dry" solder paste. However, the measure of
"dryness" is very subjective and varies from one operator to another.
Consequently, our facility is disposing too much solder paste. Is anybody
measuring the "dryness" of solder paste? If so, how are you doing this? I
need a scientific way to determine solder paste dryness, and a guide that
will let me know when the solder paste is no longer good. In addition, is
there any way to "recycle" dry solder paste? Are there any solvents or
chemicals that will restore the solder paste to its original condition?
The solder paste is currently being placed by hand on the stencil.
Before the stencils are washed, the solder paste is removed and placed back
into the jar. This results in cross contamination of new and used paste.
To resolve this cross contamination, we would like to use an automatic
catridge dispenser which is available with MPM printers. Is anybody using
these automatic dispensers? If so, do you have any "lessons learned" or
"recommendations" for using this new equipment?
-Thanks for your help,
Teo Tijerina
Conexant Systems, Inc.
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