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From [log in to unmask] Wed Jul 9 11: |
06:02 1997 |
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>From willli Wed Jul 9 06: |
44:04 1997 |
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Tom makes an excellent reccomendation here - get rid of your silkscreens!
I have struggled with this cultural change he describes while working within a major automotive company. The resistance to the change was based on two premises 1) manual insertion operators would increase the number of misinsertions and 2) troubleshoot/repair persons would have difficulty in locating features. I would argue that suppling the persons with "maps" of component locations is sufficient. Especially in the case of large volumes, after building 20,000 units - the insertion people surely know where their five components go.
Jamie McIntyre
Field Application Engineer
PCI
-----Original Message-----
From: mailnet
Sent: Tuesday, July 08, 1997 11:28 PM
To: Jamie W. McIntyre
Subject: [log in to unmask]: RE: FAB: Silkscreen
From: [log in to unmask]
Tom:
We work to a stated minimum character height of .040"
and thickness of .008". We also perform an "autoclip" of
the nomenclature, which obliterates any silkscreen
characters that fall within .008" of a solderable feature,
due to silkscreen tolerancing. Yes, "R"s sometimes end up
looking like "P"s, and "B"s like "3"s. This is why I have
been encouraging my customers for years to eliminate
silkscreen if possible. An added benefit to eliminating
legends is a cost savings of about $1/panel per side (divide
by # up per panel for piece price savings). I realize that
eliminating silkscreens requires a culture change, to say
the least, but most designs of late do not afford the real
estate necessary to screen these alpha-numerics onto circuit
boards with any degree of legibility. Many folks are
designing a different shaped pad for pin 1 (a square) in the
etch pattern for component orientation.
Tom Coyle
Field Services Engineer
HADCO Corporation
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