sam mccorkel wrote:-
>We're having trouble with boards that have large ground plane areas. The
>solder isn't as flat as we need it to be and it puddles around the large
>holes. We'd like to know if anyone out there has advise on what to adjust or
>if a different process is recommended.

Hi Sam,

Just a few thoughts. Maybe the air knives are in need of replacement. If
the slots are enlarged this can have a dramatic effect on the amount of
solder remaining. I expect you have tried the obvious of increasing
dwell time, slowing down the withdrawal speed, and increasing air
pressure. Another factor is the movement of solder in the pot. Make sure
the pump is working to prevent cold spots forming when the panel is
inserted. You could try double cycling to get a better result. The first
cycle can be considered the pre-heat.

Failing that. If there is a large ground plane, can it be covered with
solder mask or can thermal breaks be put around the holes. Is reflow an
option instead of hot air level.

We have one particular heavy backplane which is totally 2oz copper on
the outside with many large holes and do not have a problem with
flatness or solder thickness in holes so it is possible to do. Our
machine is a vertical Quicksilver.

Good luck.
Paul Gould
Teknacron Circuits Ltd
[log in to unmask]
Isle of Wight,UK

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