Hi Lang
We have experienced this on a Torroid with 4 leads. The same result one of
the leads was floating. The problem was taking about 3% off our yield. The
only way out of this situation is to talk to the supplier and get them
sorted out. In our case the supplier was squashing the package down and
forcing the planiarity. It improved things but the problem did not go away
so we reverted back to our original supplier of these devices. In the days
pick and place machines had lazer centering, I believe they were also able
to do coplaniarity checks on leads.

Sometimes if the devices are a hot item and everybody wnts them QC can
sometimes lax and let them through, better some chips than none. We
experienced the same thing with PLCC's during a modem chip shortage some
time ago, there was nothing we could do aout it. The suppliers attitude was
"if you don't want them, somebody else will take them"

If you need equipment vendors with laser vision send me an email
[log in to unmask] <mailto:[log in to unmask]>

Hope this helps

Z

-----Original Message-----
From: Mike Lang [mailto:[log in to unmask]]
Sent: Wednesday, July 26, 2000 12:07 AM
To: [log in to unmask]
Subject: [TN] Bent Leads on PLCC's


We are experiencing problems with soldering of PLCC's.

We find that a significant number of these devices are received from the
vendor with non-coplanar leads.  The lack of co-planarity causes open solder
joints.

Investigation has resulted in the knowledge that approximately 5% of the
PLCC device we receive are not within the 0.004" co-planarity requirement.
We find some to be out as far as 0.012".  I cannot currently define the
point at which the lack of co-planarity becomes an issue.

The supplier is a major manufacturer of these devices.  The parts are on
tape and reel.  We have inspected them prior to any processing at our
facility, so we know that it is not a question of in-house handling,
placement, etc.

1) Does anyone else see co-planarity problems with PLCC's?

2) What steps have you successfully taken to correct this problem, and what
was the result?

3) Are there pieces of equipment I can put inline to screen <*gasp*> out
these devices?

4) Any assembly or processing tricks you have used successfully to
compensate?




Thanks,

Lang
x5046

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