Hi
I have designed Ovenized oscillators operating in the 85 degree C range. At
first we used standard FR4. The boards would turn brown and look as they
were about to fall apart after a year or so. We switched to a high temp
laminate G200 from Allied Signal at that time. The BT epoxy types have a
higher glass transition temperature. Our board house was able to suggest one
that they had used in the past.
Dave Eloranta
Locus Inc.
[EMAIL PROTECTED]


-----Original Message-----
From:   [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On
Behalf Of Jon Elson
Sent:   Wednesday, July 17, 2002 5:07 PM
To:     Protel EDA Forum
Subject:        Re: [PEDA] 90 degree C?

Michael Biggs wrote:

> Hi all,
>         Anyone run very hot traces @ like 90 degree C on there PWBs and or
> use surface mount heat sink around the component( like a D-PAK)?
> Thanks for any response.
> I know this is a Protel questions group but everyone seem knowledgeable in
> design layout.

I would assume that over a fairly short time the epoxy holding the copper to
the laminate would deteriorate, and the foil would lift off the board due to
the thermal mismatch.  Some cycles of this might cause the foil to crack.

I'm pretty sure a recognized safety testing lab would not approve any
device designed that way, if they discovered that is what you were doing.

Using a foil area to draw heat away from a heat source is pretty common
practice.  I imagine some people let their junctions run at 90 C, but I
suspect the heat sink surface runs cooler than that.

Jon


************************************************************************
* Tracking #: E17219ECD51CDF48ACDF490FB27BDC77807B5A59
*
************************************************************************

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Forum Guidelines Rules:
* http://www.techservinc.com/protelusers/forumrules.html
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to