We have been building boards with 1206's SOIC's and SOJ's on solder side
built first, both soldered and glued, then flipped over an built component
side with 1206's SOIC's and 25thou Fine Pitch. The boards then pass
through manual assebbly and insertion machines before going over the solder
wave. All of the solder side of the board is exposed to the solder wave. I
have not heard of any reliability problems with the products to date. All
of our newer products are however double sided reflow and selectively
soldered at the wave. This is now seen as a preferred practice.

Martin Bourke
[log in to unmask]
00-353-61-485319

_________________________________________________________________________


At 05:20 PM 10/6/97 -0400, you wrote:
>In an effort to decrease defects on a mixed technology assembly with simple
>SMT's on the "solder side" and thru-holes on the "comp side", we have adopted
>the following process:   We are first gluing, solder-pasting and then
>reflowing the SMT's.  We then flip the board, stuff the thru-holes, and
>wave-solder.  This has enabled us to eliminate the "opens" with the reflowed
>solder paste on the SMT's and dramatically reduce the "shorts".  However,
>this process means the SMT's are reflowed and then waved.
>
>The big question:   Are we introducing potential reliability problems?  Has
>anyone out there also done this with no adverse long-term reliability
>problems?
>
>All feedback is welcome, especially good news!    Thanks, all.
>
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