Howard,

For your second question, another important consideration for Tape Vs Tray
is whether the components are classified moisture-sensitive and what MS
level. Even for robust components like BGAs, keep in mind that the benefits
you get from tape and reel can be more than offset by the fact that you will
have more parts per unit resulting in longer exposure time and especially
the longer bake time required. In a high temp tray the default bake cycle is
48 hours at 125C and in a reel it is 79 days at 40C...(ref. J-STD-033A).

Francois Monette
Cogiscan Inc.


Date:    Wed, 9 Jul 2003 10:16:59 -0600
From:    Howard Watson <[log in to unmask]>
Subject: SOT 23 placed upside down

Dear Technet folks,

I am obviously not following the search protocol properly for the
information that I need, so I'll just post my Q's anyway.  First question
relates to a problem I'm experiencing with some SOT 23's that get placed
upside.  This occurs on multiple machines/feeders, and my hunch is that
the component somehow is flipping upside down in the pockets while in the
feeder.  Anyone have experience with this problem?  I did change the laser
centering parameters so that it gets rejected now if it's upside down, but
I'd like to figure out the root cause.

My second question is regarding QFP components in trays or tape & reel -
is there a standard or recommendation for putting fine pitch QFP's in
trays verses tape & reel?  In other words, are 25 or 20 mil pitch gull
wing QFP's OK to be supplied in tape & reel, or should they be in trays to
avoid lead damage?  We always get these components in trays, and I figured
it was to protect the leads, but now I wonder if tape & reel is fine.  I'm
sure it depends somewhat on the feeders, and their ability to deliver the
components without damaging the leads.  Any advice will be greatly
appreciated.

Howard Watson
SMT Manufacturing Engineer
AMETEK/Dixson

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