thanks clive.  we are recreating some boards that were used as spares
in an old system, and the spares are getting thin.  one of the requirements
is that the boards be as close to original as possible.  because they go
in the plane (part of a radar jamming system), if they are not considered
99% equivalent in form, fit, and function, then flight verification is
necessary...
a very cost-prohibitive process.

the heat sinks are rivetted on one side only, so although they are not going
to come off even if they come "unglued", they could still theoretically flop
around a bit.  and the only problem with no solder mask is during the build
process.  after the boards are populated, they are conformal coated.

and as brad and you and others have suggested, i need to try doing a 
fill on the solder mask layer.  as everybody can probably tell, i'm learning
protel on a need-to-know basis, which is probably not an optimum method.

thank you for your comments,  miker

> -----Original Message-----
> From: [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, September 19, 2001 5:52 PM
> To:   Protel EDA Forum
> Subject:      Re: [PEDA] eliminating solder mask ??
> 
> 
> 
> Do you need to remove the solder resist so you can glue???? the heatsinks
> to
> your board?, better be safe and use what every  other professional
> designer
> would use which would be screws.
> 
> If you are thinking about removing the entire solder mask, you will have a
> board
> with completely conductive traces which I would imagine would cause major
> problems. If you really must glue your heatsinks, just put a fill on the
> solder
> mask layer.
> 
> 
> 
> 
> 
> 
> 
> 
> "Robison Michael R CNIN" <[EMAIL PROTECTED]> on 09/19/2001 10:16:00
> PM
> 
> Please respond to "Protel EDA Forum" <[EMAIL PROTECTED]>
> 
> To:   "'Protel EDA Forum'" <[EMAIL PROTECTED]>
> cc:    (bcc: Clive Broome/sdc)
> 
> Subject:  Re: [PEDA] eliminating solder mask ??
> 
> 
> 
> thanks to all who responded.  i've absorbed some of it and i'm still
> chewing on the rest.
> 
> the one comment that i just tell the board shop not to solder mask it
> is going to work.  i called advanced circuits (hope i'm not breaking the
> rules by mentioning them) and they said not only was it no problem,
> but since i've already gone thru the proto run, they would not charge me
> for nonrecurring engineering costs on the production run, even though
> there is this slight change.
> 
> and i cringed when a few suggested that i just cut it out of the gerbers,
> because other than changing a bit of silkscreening and simply reviewing
> other files, i know very little about gerbers and how to manipulate them.
> i was relieved when someone finally gave me the "gerber for dummies"
> advice to delete the GTS file (turned out the top is all i need to get rid
> of)
> and add a comment noting its absence in a readme file.
> 
> there was also talk about just deleting the mask where the heat sink
> goes, and a polygon "pour" or "fill" was suggested here.  i have never
> done this before.  i'll have to dig into the documentation and find out
> how
> thats done.
> 
> again, thanks to everyone for helping.
> 
> miker
> 
> > -----Original Message-----
> > From:   Richard Thompson [SMTP:[EMAIL PROTECTED]]
> > Sent:   Wednesday, September 19, 2001 3:39 AM
> > To:     Protel EDA Forum
> > Subject:     Re: [PEDA] eliminating solder mask ??
> >
> >
> > > production is having trouble getting some heat sinks to stay "glued"
> to
> > > the solder mask on some prototype boards.  the decision has been
> > > made to not use a solder mask.  the boards will be conformal coated
> > > anyway.
> > >
> >    >>
> >    We normally just add a fill to the solder mask layer to remove mask
> > from the area under the heatsink and leave mask over everthing else (it
> is
> > very useful to stop shorts etc)  seems to work ok for us on many boards.
> > asuming of course no tracks running under the heatsink ;-)
> >
> >    Rich
> 
> 
> 
> 
> 

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