The Maximum Operating Temperature of FR4 is 130 to 135C (depends on the
specific material and fabricator). I can't comment more than that, but I
am sure others on this forum can add to that thought - I throw it out
there to stimulate the conversation.

The Tg really relates to what happens at the higher assembly temperatures
... not so much the working environment.

Valerie





Denis Lefebvre <[log in to unmask]>
Sent by: DesignerCouncil <[log in to unmask]>
04/21/2005 05:11 PM
Please respond to "(Designers Council Forum)"; Please respond to Denis
Lefebvre


        To:     [log in to unmask]
        cc:
        Subject:        Re: [DC] High Temperature Environment

I only mentioned the Isola FR408 because I know it's readily available and
not too pricey. The intent, obviously, is to use a material with a higher
Tg than standard FR4. I believe FR4 is rated at 135C. (don't have any data
handy)

-----Original Message-----
From: Brooks,Bill [mailto:[log in to unmask]]
Sent: Thursday, April 21, 2005 2:01 PM
To: [log in to unmask]
Subject: Re: [DC] High Temperature Environment


Dennis,

That seems to be a great choice based on the limited information
supplied...

If more margin is needed for unknowns you could try the FR406 IPC-4101/26
which has a minimum Tg of 170 deg C

http://www.isola-usa.com/images/uploaded/FR406Bulletin-1.pdf

FR408 IPC-4101/24 has a minimum Tg of 150 deg C although ISOLA brand
material claims 180 deg C. But I am basing that off the IPC-4101 spec.

http://www.isola-usa.com/images/uploaded/FR408Bulletin2.pdf

I would specify the IPC-4101 spec because that is not vendor specific.


Bill Brooks - KG6VVP
PCB Design Engineer, C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
_______________________________________
Member of the San Diego Chapter of the IPC Designers Council
Communications Officer, Web Manager
http://dcchapters.ipc.org/SanDiego/
http://pcbwizards.com

-----Original Message-----
From: Denis Lefebvre [mailto:[log in to unmask]]
Sent: Thursday, April 21, 2005 1:19 PM
To: [log in to unmask]
Subject: Re: [DC] High Temperature Environment

I think I'd be inclined to go with FR408 or any IPC4101/24 grade material.

-----Original Message-----
From: Don Larisey [mailto:[log in to unmask]]
Sent: Thursday, April 21, 2005 1:13 PM
To: [log in to unmask]
Subject: [DC] High Temperature Environment


We are looking at putting a small board with all components rated to
125C into a sustained working environment of 120C. Should we be
specifying a different board material other than FR4. This is a small
double sided board about 25mm X 40mm with components both sides.

Any comments???

Don



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