Juan,

are you sure these are cracks? I've seen similar on glass diodes, and in that case it was not cracks, but circumperipherical rings or interface created by the glassing process. 
Just a lateral thought-
q.e.s.m.
Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Juan T. Marugán
Sent: den 11 oktober 2007 23:33
To: [log in to unmask]
Subject: Re: [TN] Cracks in the body of glass diodes (JANTX1N4148UR1)


Well, a couple of comments:

Of course we have identified the manufacturer and its supplier. The manufacturer is one of the most important semiconductor manufacturers. We have received diodes from two different locations: the diodes manufactured in the USA are defectives while the diodes manufactured in Europe are Ok. There are several date codes affected by this problem.

We have also noticed that the shape of both diodes -European and American- is not exactly the same, apart from the color of the band (cathode)

Inge, you asked me why we accepted the components. The answer is because we didn't detect anything during incoming inspection. The photographs you have seen have been taken with a magnification higher than 50X. The diodes have a length less than 4 mm and a diameter of about 2 mm. 
We were investigating a problem in a board when we found "something" in the glass body of these components. Our first though was the damaged occurred during the soldering process but at the end, we have verified that the diodes removed from the tape of the reel have also the same problem. That is the most important difference with the defect reported in the Nasa advisory.

By the way, thank you for your comments.

JuaN

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