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Tue, 14 Sep 2004 09:33:20 +0800 |
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This is Lionel:
Actually your question is a lot more complex than at first considered. I
would have to ask first, "Is this CHEMICAL or PLASMA etchback?" There is a
lot of difference between the two. I would refer you to a round robin
performed by ITRI a few years back; the #1 result was obtained using
plasma.
I have seen a lot of problems with chemical etchback, particularly with
ultra-small holes. The problem has been either residual chemistry
remaining, or incomplete etchback, due to mass transfer problems.
However, the specific energy choice for plasma is also a problem; mega
versus giga hertz systems produce radically different results.
As to answers, I find that flex or polyimide manufacturers tend to be much
more secretive than standard rigid board people. Not much in the
literature, I am afraid.
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