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Date: | Fri, 08 Dec 1995 09:34:25 EST |
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TO: I1263600 IBMMAIL ipc internet technical query
FROM: DSTEWART EX2 D.Stewart - Product Development Manager.
DATE: 8 December 1995
SUBJECT: PTF - screened EMI shielding
REFERENCE: assembly
I have just read an article from Circuitree on the use of screen
printed polymer thick film for EMI shielding. This technology has
been known by us for some time, but up to now it has not been asked
for. Before I start a project to characterise the process, I would
like to know if people are using this process for their EMI
shielding on SMD boards.
As all the SM gurus and solder paste experts keep telling
you assembly people that, ideally soldermask must be below the
level of the pad, how do you cope with effectively 3 layers of
soldermask and one layer of copper paste, over the top of your
tracks (which always seem to end in a pad !!)?
Circuit Wise, Photocircuits and AMP+Akzo are all mentioned
in this article as using this technology, so let's hear from you,
if not your customers, on what effect this has.
Dougal Stewart
Exacta Circuits
Scotland
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