Mike,

In accordance with my text authored by Ray Prassad he states that
coplanarity is the maximum distance between the lowest and the highest pin
when the package rests on a perfectly flat surface.

0.004 inch maximum coplanarity is acceptable or peripheral packages and
0.008 inch maximum for BGA.


-Gary








Sure, no problem...

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


>>> [log in to unmask] 07/26/00 02:57PM >>>

Mike,

I'm just a summer intern but I have all my books and references here with
me.  Could you give me your question again??

Thanks

-Gary



-----Original Message-----
From: Mike Lang [mailto:[log in to unmask]]
Sent: Wednesday, July 26, 2000 2:43 PM
To: [log in to unmask]
Subject: [TN] PLCC Coplanarity... (or lack of)


I got very little response to my coplanarity post, which leads me to believe
that either no one else is having the problem, or no one else is using
PLCC's, or...

Is anyone out there using PLCC's without the coplanarity problems?




Thanks,

Lang
x5046

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