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Yep it does seem odd, but here's how I would rationalise it:
plasma etching could be doing two things:
1) activating surface to improve poor adhesion
2) reducing effects of moisture ingression when it does reach surface.
Course, if you had a better adhering more protective product then maybe you could dispense with
the plasma......
Mike Fenner
----- Original Message -----
From: Alan Brewin <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, May 26, 2000 11:41 AM
Subject: Re: [TN] Solder Mask
> Jerry,
>
> It just doesn't make sense (to me anyway) to go to the effort of plasma
> etching to get adhesion, and they to use a silicone material. Silicones
> generally do not have good adhesion. I feel sure that if you use an acrylic
> or urethane material (providing your board is pretty clean) you won't have
> to plasma etch.
>
> Your comment about rework surprises me, I may be missing something? It has
> always been my experience that acrylics are a lot easier to re-work than
> silicones/RTV's. Do you want to chemically remove/rework or are you
> soldering straight through the product?
>
> I also agree with Brian about the danger of relying upon reported dielectric
> properties of a material measured at STP rather than at higher humidity if
> these
> conditions will exist in your end application.
>
> Alan Brewin
>
> Concoat Ltd
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