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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