Steve expounds thusly:

"
There's an assembly that we build here that has two 352-pin ceramic 20-mil
pitch, gold plated leads, QFP's that only comes in a carrier that has to be
pre-tinned, cut and formed, prior to placement and reflow. We do the
pre-tinning and cut and form ourselves in-house with a Mannix press and
adjustable die. You can imagine what fun that is...

My question is (and I'm pretty sure I won't get a good answer) why in heaven
do the component vendors supply the parts only this way?"

Hi Steve!
My guess would be that if they were formed, tinned and placed in matrix
trays, they'd never make it though shipping intact....so what'd be the point?

We had some 224 pin 20mil parts at DEC Albuquerque that never once made
it through the shipping process intact. I wrote a program that did a "no touch"
coplanarity and skew measurement (on a computer controlled CMM)
while in the matrix tray (which was pretty neat, if I do say so...albeit slow!).
I dont think we ever had a good lot received this way!
I believe in some forms, the leads are just too fragile to maintain their
original
geometry through shipping and handling (and the receiving dock!), so a
"just in time" forming might seem a realistic plan.

Still a pain, Im sure though!
:-)
Thanks
John

Square D Component Engineering
Raleigh NC
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