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From: [log in to unmask]
Date:  7 May 96
Subject: RE: ASSY: Dual LED failures.
To: uunet!zytec!uunet!manserve.com!Myron.Papiz

Myron:

If you have devices available from before the problem 
re-surfaced, compare them to the ones that are currently 
failing.  We had a similar open LED problem and found that the 
ones that failed had smaller "posts" or "flags" for die attach 
inside the encapsulant/lense as compared to devices which did 
not fail.  The larger area apparently provides enough 
heatsinking to prevent stress on the die attach or wire bond.

We also found that even though we call out one part number, the 
LEDs could actually be coming from a number of different 
manufacturers.  Many companies such as IDI and Chicago 
Miniature don't actually manufacture LEDs, but rather buy from 
several sources and then re-sell or do value added (such as 
your dual array) and sell.  If you do indeed find a 
construction difference between failing and non-failing 
devices, I would insist on the one type only, and try to get 
your source to divulge the original maker of both types.

Regards,


Pat Bailey
Supplier Quality Engineer
Zytec Corporation
507 637-2966 x355
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