 
| >From willli Thu Jun 26 12: |
51:01 1997 |
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| From [log in to unmask] Fri Jun 27 10: |
54:39 1997 |
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Most recommendations come from the mask suppliers and most mask suppliers
that I have worked with prefer pumice scrub which is what we do here. Second
choice is 320 grit scotchbrite and chemical clean is way down the list.
We do not pre-bake but depend on the dryer after the pumice rinse section to
adequately dry the boards.
Puddles around the holes with a DP-10 may be due to the jog being off. When
you print panels with holes the ink over each hole does not transfer from the screen
to the board but builds up on the back side of the screen. After several panels the
blob is so big id drips onto one panel next to the hole. The trick is to move the holes
to a different spot each time so it can't build up. We flip the panels a different way
each time. The machine has also got what is called "jog" built in. The jog alternates
the stop position of the panels as they travel in. It is adjustable from 0 to maybe a
half inch.
----------
From: sam mccorkel[SMTP:[log in to unmask]]
Sent: Thursday, June 26, 1997 1:01 PM
To: [log in to unmask]
Subject: Fab: LPI soldermask
Before solder masking we scrub our panels using a 320 bristle brush. What
TYPE of brush and grit SIZE is most recommended?
Suggested pre-bake cycles seem to vary from one source to another. What is
the most recommended time and temperature for baking panels just BEFORE
applying LPI solder mask?
We apply LPI ink using a DP-10 and are experiencing solder mask "puddling"
beside the holes. How can we eliminate this cosmetic problem?
All comments and suggestions are greatly appreciated!
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