TN'ers:

We're getting a handful of bridges at wave solder on a few designs.  We've
tried A, B, and C, but they continue to show up consistently on some styles
of connector behind chip components, and on trailing leads of flatpacks.

The machines is a fairly new Electrovert with convection preheat, Lambda
wave, and chip wave.  We're using Sn63 at 500F with RMA 25%.

We're looking at a hot air knife retrofit, which would be turned off on
everything but problem boards.  We've had a demo, with mixed results.  Good:
bridges were much improved, and no insufficients.  Not-So: some frosty
looking joints, which we expected, but also a lot of solder balls and
splashes.

We've heard that setup can be touchy, and we didn't expect to optimize on a
two board sample, but we're not sure what we can conclude here.
Unfortunately, the demo was not apples-to-apples - it was performed on an
inerted machine with an A-type wave, and we're not sure if the splashing and
balls could be attributable to the increased surface tension.

Anyone out there have good things to say about their hot air knife?

Joe Kane
Lockheed Martin Control Systems

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