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October 2010

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Thu, 21 Oct 2010 21:28:14 +0200
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Bob,
I wouldn't be worried about the FR-4. They can cope with +200 C for short 
periods. I  would rather be worried for the IC's. If they heat the board to 
more than one hundred centigrades, what then about the chip temperature? 
Chips withstands +150 C or more, but most use to derate them to a 
temperature for a long life.

Why not use a multilayer ceramic board if you need a high temperature 
application?

Inge


----- Original Message ----- 
From: "Robert Kondner" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October 21, 2010 7:12 PM
Subject: [TN] FR4 Temperature and Life


> Hi,
>
>
>
> I was looking around and I found some references to "FR4" as having a Tg
> from 100 to 130 C. I was surprised as I thought that seemed low.
>
>
>
> Now I understand that FR4 is a pretty wide brush and it covers a lot of
> different materials and different suppliers.  BUT, I was wondering what
> "Most" PCB vendors are supplying and how the Tg affect life with hot
> components.
>
>
>
> I have some small QFN parts that tend to run hot, PCB temps of 100C or a
> little more. Forgetting thermal cycling for a moment does a 100 to 120 C
> temperature induce failures in other area like copper foil to base
> separation, de-lamination, solder interface or any other failure mode?
>
>
>
> Any pointers to literature?
>
>
>
> Thanks,
>
> Bob K.
>
>
>
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