The only time I have seen that is when the back side was totally exposed
ground and was to be lap soldered (or more like welded?) to an aluminum
pallette for installation. I am almost sure we attached the aluminum
pallette first before we stuffed the parts, and then reflowed. Could that be
a factor? Is it multilayer? The other alternative was using Rogers 4350 with
a ground plane 5 mils down for the critical areas, and the rest of the
components were routed just like any other board. Rogers 4350 has the
properties of Teflon but can be processed like multi-layer FR4 (well, it has
its challenges, but it worked)

Hope that helped?
Jack

 -----Original Message-----
From:   Marsico, James [mailto:[log in to unmask]]
Sent:   Tuesday, September 26, 2000 10:11 AM
Subject:        DENSE SMT ASSEMBLY

Hello Technet:

Well, the Electrical Engineers did it to me again!  They're designing an
assembly consisting of a Teflon surface mount board .005" thick,
approximately 1.5 x 1.7", with 320 components!  The component mix is mostly
0402's (resistors, caps and inductors) and 30 SOT-363s.  Does anyone have
any suggestions as how to automate this assembly process?

Thanks in advance,
Jim Marsico

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