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July 2003

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Subject:
From:
Chris Murphy <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 11 Jul 2003 08:22:48 +1200
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Hi Howard,

we have been picking fine pitch QFPs up to QFP100 size from tape for years with no coplanarity or moisture issues.
There are no problems with lead damage caused if the tray is knocked by an operator when loading the tray into the tray
feeder and parts jump out, there is no possibility of incorrect rotation caused by an operator putting the tray in the
wrong way around, less downtime from reel / tray changeovers as we can fit many more parts onto a reel than a tray, no
reduced placement efficiency if you have a placment machine with a slow tray feeder.

I am curious as to why people are baking their parts?  Surely if you keep it in it's vacuum package until it is needed
and store it in dessicant cabinets when off line then it should be OK?  (Sorry if this is a stupid question.)

Regards,

Chris Murphy,

Production Engineering,
Tait Electronics

Francois Monette wrote:

> 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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