Hi Jack -

The callout is adequate, assuming tolerances are stated elsewhere on the
drawing.  Experience, from having attempted use of countersunk holes in both
epoxyglass and polyimideglass boards, says someone is going to break some
boards.  The laminate materials just don't hold up to the force applied by
this type of fastening arrangement.

I would suggest you explore your alternatives, such as a straight hole
covered by a countersunk automotive trim washer or similar.

Regards - Kelly


-----Original Message-----
From: Jack Olson <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, September 24, 1999 5:29 PM
Subject: [DC] PCB countersunk holes


>I have never been asked to provide countersink mounting holes on a PCB
>before.
>Since I have never had a drafting class, can I ask if any of you typically
>do this?
>I was just going to add a note to the fabrication dwg saying:
>
>x.) Countersink mounting holes (8X) 82 degrees x .230 on component side.
>
>Is this adequate?
>Are there any "gotchas" I need to keep in mind?
>
>Jack (the new guy)