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Date: | Thu, 21 Oct 2010 15:05:53 -0400 |
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Hi Bob,
With your application you want to have a Tg of at least 150C—you need to remember that glass transition is a process that takes place over about a 50C temperature range; so for Tg=150 it starts at about 125C.
The biggest issue most likely will relate to barrel fractures.
Werner
Upcoming workshops:
November 2 & 9, SMTA Webtorial,
“Fundamentals in Solder Joint Reliability”
December 7 & 14, SMTA Webtorial,
“Acceleration Models, Accelerated Reliability Tests and ScreeningProcedures”
-----Original Message-----
From: Robert Kondner <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Oct 21, 2010 1:12 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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