To: Moss Dore
From: Paul Waldner
Re: Potato Chipping

Potato Chipping ("Potatoe" to us conservative Republican types) or "warp and
twist" is usually attributed, at least in my experience, to a lamination process
which is heating up or cooling down too quickly or too unevenly.  It is solved
by:

	adding a tempering cycle after lamination. (post bake)
	adding lag material to the stack for the press build-up (tending to
slow-down the 		heat-up and cool-down of the press cycle)
	changing the heat-up and/or cool-down rates in the press
	changing the way a multilayer is constructed to eliminate or minimize any
"uneven" 		character of the build.

Sometimes the design of a board pre-ordains it, by virtue of where copper masses
are placed, to look like a potato chip.  Good communication between fabricator
and designer should help preclude such situations.  Good luck and may all your
future boards look as flat as a pancake!

Paul Waldner
Multiline
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