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August 2000

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From:
"Jason Larson, AScT" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 2 Aug 2000 09:27:41 -0700
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Mark, thanks for the interesting information.

What process do you use to electrical test the diode during insertion?

Thanks
Jason Larson

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Ross, Mark
Sent: Wednesday, August 02, 2000 8:41 AM
To: [log in to unmask]
Subject: Re: [TN] diode failure summary


Jason,

We had this happen to us in the past.  Here is the first thing to ask your
vendor:

"Did you change which facility finishes the encapsulation?"

If you take the die, add leads, do the encapsulation and everything is
running just fine and then have this happen out of the blue ask them this
question first.  In our case, they moved from a facility that had been doing
it for years, to one in India which had not ever done it and the resulting
failures (lucky for us) showed up during insertion (we read the axial
components electrical values during insertion).

If this is not the case, there is something that I have seen lead to this
before.  The first is not well documented in a lot of data sheets nowadays,
however there is a minimum lead to bend ratio that must be followed or else
you can stress fracture the unit at the die level and it could open or it
could short, it depends.  Make sure that the minimum lead length before
bending is being followed.  This MUST come from the manufacturer.  We had a
rule that no 1W zener diodes could be placed at less that 1/2 inch total
part span if the diode was glass encapsulated and no shorter that 0.450" if
it was encapsulated like a rectifier diode.  Any shorter would lead to
eventual failures.


Mark Ross
Electronic Design Engineer
Innovative Home Products Inc.



-----Original Message-----
From: Jason Larson, AScT [mailto:[log in to unmask]]
Sent: Wednesday, August 02, 2000 11:24 AM
To: [log in to unmask]
Subject: [TN] diode failure summary


Well the original attempt at sharing the pictures wasn't good, so lets try
again!!


<http://www.driveway.com/share?sid=8a88c806.9c647&name=Electronics>


Jason Larson

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