Don
Ah, gosh, again a question from the past that I don't have values to.  I was
doing TAB with ~100um wide leads, and the pull strength was about 25-100
gm/lead (again, if memory serves me).  Even so, I wouldn't have done 42
gauge (how big is that in metric terms) copper wire.  Regardless, YOU NEVER
WANT THE WIRE TO PULL AWAY FROM SOLDER!  That's a failure.  You want either
the wire to break far (at least a few mm) from the pad, or you want the pad
to pull off the substrate.

Having had to get some numbers without the proper tools, I found you can do
a garage experiment by attaching a strong clip (like a vise-type paper
clip), tie a string, and hand weights.  Don't forget to get it to hand
perpendicular to the bond (that's the weakest direction).  It sounds hokey,
but the numbers are within 30% of a "industrial" set up (I had a
collaborator elsewhere).  Or you can spend lots of bucks and get the same
number.


-----Original Message-----
From: Steffen, Don E <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Wednesday, October 13, 1999 1:47 PM
Subject: [TN] Pull Strength Value


>Techno's
>
>I have an anomaly that I wonder if anyone out there can help me with. My
>customer is asking me to come up with a Pull Strength value. The
discription
>of the anomaly is that I have a 42 gauge, Copper ciol wire that is hand
>soldered to a gold plated terminal. I need to quantify the strength of the
>solder bond of the 42 gauge wire that is soldered to the gold lead. I want
>to due a pull test of the wire with a Chillion Pull gage. Does anyone out
>there know what the value that is considered to pull a wire away from
>solder? How is this test performed?
>
>Senior Quality Engineer
>VDO Control Systems
>Auburn, IN 46706
>Phone (219)925-8887
>Fax (219)925-8710
>Email: [log in to unmask]
>
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