Steve,

DONT EVER THROW ANYTHING OUT SIMPLY BASED ON SHELF LIFE!!!
Suppliers will spec in a shelf life well within a worst case scenario of storage conditions.
The 6 month shelf life on Prepreg I feel is arbitrary at best. To eliminate the shelf life issue for B stage, I simple added to our procedures that after the manufactures shelf life has expired, we can ( and do) retest the material by scale flow methods. We will then certify the material for an additional 30 days. We will simply keep re-testing as needed. As long as it passes the test, we will use it. This has never been a problem for me or any facility including military shops. As long as the Government ( DSCC) has approved your procedures, I consider the re-testing to be viable and compliant.   

Hope this helps.

Ed Cosper
Director, Quality Assurance and Engineering
Graphic Electronics Inc.
Tulsa, OK

----------
From:  Steve Sekanina[SMTP:[log in to unmask]]
Sent:  Wednesday, March 05, 1997 3:47 AM
To:  INTERNET:[log in to unmask]
Subject:  Prepreg shelf life.

     We store our prepreg in an enviroment of 10% RH and 65 degrees F 
This prepreg is mil certified FR4.  After 6 months of sitting on the 
shelf, this material is no longer certified by our supplier as mil 
spec.  This material could then be used on non mil spec work.  What 
method and  what time frame should be used to determine when the 
material should be thrown out?  (not used on anything)  In other 
words, after the six months, we know the material is not scrap, but at 
what time will it actually become defective? Any input on this 
subject would be appreciated  Thank you..

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