[log in to unmask] wrote:
> 
>           I have just recieved results to a TMA test for z-axis expansion and
> a TGA for weight loss on a 260 Tg polyimide material.  I was told that the
> results are bad, however, I have nothing to bench mark the results against.
>  Does anybody know what a typical good result for these tests are for this
> type of material and or any other materials.  Any comments would be greatly
> appreciated.

We have one high reliability electronics customer that specifies a 
minimum Tg 250 degrees C on polyimides.  Generally, the higher the Tg 
the lower the coefficeint of thermal expansion in the temperature region 
that boards see during processing.  This in turn means less stress in 
the plated through holes.  The Tg of polyimides may be lowered by 
moisture content.  You may want to dry the boards if they have had a 
chance to pick up moisture.  

As far as TGA goes, this is not typically performed on boards or cured 
board materials.  But, it will give an indication of resin content and 
may provide you with some useful information.  If the resin content is 
significantly out of tolerance it will impact the board thickness.  
You may want to check the overall thickness as well as the 
dielectric thickness on each layer.   

-- 
John Moylan
President

Delsen Testing Laboratories, Inc.
1024 Grand Central Ave.
Glendale,  CA  91201

Phone:	818 247 4106
FAX	818 247 4537
email:	[log in to unmask]
URL:	http://www.primenet.com/~delsen/

Delsen Testing Laboratories, Inc. is an independent testing
laboratory primarily engaged testing advanced materials.

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