[EMAIL PROTECTED] schrieb:
>
> In a message dated 5/17/2002 4:30:53 AM Eastern Daylight Time,
> [EMAIL PROTECTED] writes:
>
> > I get what is Solder Mask layer but what I don't get is why do we need paste
> > layer after this? I blv both are almost the same thing... There would be
> > holes in the solder mask layer and there we can apply the paste even if its
> > the case of surface mounted components... Please explain...
> >
>
> Two examples of why they need to be different:
>
> 1) The soldermask is usually "pulled back" a few mils around pads, to ensure
> that no soldermask covers any part of the pad due to the inevitable slight
> misregistration, while you don't want paste applied to bare substrate, only
> to the actual pad itself.
>
> 2) Edge fingers to insert in a card edge connector. Here you need the
> soldermask removed to expose the contacts, but you don't want paste on them
> either.
>
> And there are many special cases as well.
>
> Steve Hendrix
Waheed, Steve
One more example from me: You need a soldermask pad for every PAd, ThrougHole,
SMD even for mounting holes. But Past-masks you anly need for SMT-Pads. That is
why Past-mask came up with SMT first.
.... Remember earlier times, when things where less complicated... ;-)
Greatings,
Waldemar
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