Michael,

I would not think your baking method would have caused warping under
normal conditions.

We have some customers that bake our boards (we're a fabricator) both
flat and vertically and each believes their method to be the perferred
method. We only recommend baking them at temperatures similar to those
you describe.

We have had boards warp a long time ago while being cured after solder
mask, but this was attributed to the operator losing track of time and
board width being 0.031" thick.

As far as hit or miss, it has been my experience those people that use
the term 'hit or miss' typically do not fully understand their process.
One would hope to have a full understanding of one's processes so as to
1) have better control, 2) know what to expect when a process does tend
to run amock (as they will eventually do)

Unbalancced construction would cause warpage but this would usually be
observed and controlled by the fabricator. I can't think of anything
other then too high heat or too long dwell in heat that would cause
warping of finished boards.

Hope these ramblings help...

Franklin

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