Neil Maloney of Contemporary Control Systems asks,

           Solid Solder Deposit(SSD) technology

           1. Does it work?
           2. Is it cost effective?
           3. Is there a "no-clean" sticky flux?

I have used the Precision Pads Technology (PPT) solid solder deposit method
for attachment of miniBGAs (10-mil dia. pads on 20-mil pitch and 15-mil dia.
pads on 30-mil pitch).  In my case I used a liquid RMA flux and cleaned it
off after assembly.  However, the sticky flux you refer to is merely solder-
paste flux so I don't see why you shouldn't be able to get no-clean.  Talk
to your solder-paste supplier.  Our mBGAs were bumped with 7-mil bumps of
63-37 eutectic solder.  I had NO bridging and NO opens in any of the samples
I soldered.  I supplied the boards for application of the PPT solid-solder
deposits with electroless nickel, gold flash pad finish but OSP would 
probably work too.  Our volumes are small, prototype lots so I can't speak
to the issue of cost effectiveness as compared to stencil printing in volume
production.

The stuff worked GREAT!  In fact, if you want to convince yourself how good
it is, try soldering J-leaded devices in a vapor-phase machine.  You get
virtually NO wicking of the solder up the leads and a great joint.

If you want further details, contact me off-line.

Gary P.
---
                                  Gary D. Peterson
    _/_/_/   _/    _/  _/        SANDIA NATIONAL LABORATORIES     _/_/_/
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