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August 1997

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Subject:
From:
MR GEORGE D GREGOIRE <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Sat, 16 Aug 1997 00:05:10 -0500
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Christian, SSD, solid solder deposits, refers to the pre-placement of
solder, usually at the bare board fabrication stage.  A variety of
methods have been used to place the solder, including
electrodeposition (plating), and molten deposition, then flattening
them.  I was one of 4-5 speakers who talked about it at last year's
Nepcon West/Anaheim; suggest you see the Proceedings.  Since I was
invited too late to submit a written paper, permit me to tell you
about "Deep" Solid Solder Deposits.  DSSD has solder that goes INTO
the board.  Happens as follows:  Using IMPRINT Patterning (sort of a
precision "hot stamping" into special PWB uncured "laminte"), U-
shaped recessed pads (and grooved, X-Y traces) are formed, plated,
etched.  The unexpected result of this work is that, for ordinary
fine-pitch designs, the "cups" fill up with solder and the top of the
solder is quite flat.  In assembly, as with other SSDs, a sticky flux
is used to hold the component's leads in place.  In the case of DSSDs,
 the leads move down and into the molten solder during reflow.  For a
much more thorough explanation, please see the issue of PC Fab
magazine that just came out (I authored a 2-p. article on IMPRINT
Patterning here).  Hope this is not too commercial and informatiive.
Sincerely, George Gregoire
(President, Dimensional Circuits Corp., San Diego, CA;  DCC is the
inventor of the Imprint process, which is expected to be licensed)


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