Christopher,

Aramid PWB material is used for some ceramic BGA designs to manage CTE 
interactions.  We have experienced an incompatibility with OSP and aramid 
material.  This is primarily due to the hygroscopic nature of aramid which 
requires an exaggerated pre-baking before re-flow and this process degrades 
the OSP coating useless.

Kevin Thorson
Loral Defense Systems - Eagan
 ----------
From: TechNet-request
To: technet
Subject: OSP's
Date: Monday, April 22, 1996 10:51PM

We are starting to review Entec OSP for use on our printed circuit brd
designs.  I am sure there are a large number of you that are using this
presently and I would like to get your thoughts.  We would be using this
material on double reflow designs with a water soluable flux. Heurikon
designs have components that range from 0805 chip to 304 QFP's and large I/O
BGA's. We control volume of paste with a 6mil thick stencil by reducing
apertures. I am concerned about the areas of the surface mount pads that we
do not apply solder paste to. To use OSP's do we need to change our paste
stencils? Will the water soluable fluxes wet properly without nitrogen? Are
there other things that we should be concerned with.


Thanks in Advance
Christopher Byrne
Mfg Eng Mgr
Heurikon Corp.
8310 Excelsior Dr.
Madison, WI 53717
See Heurikon's Home Page at http://www.heurikon.com