Wade,

Just a small point,

If your are have to use a pallet - use it to the  maximum benefit.

Often you can (print) place and reflow both top side and bottom side in one
hit(dependent on pad pitch).
Think about the cost savings!
        No line changeover
        No Single side stock
        Easier product management
        One stencil
        One placement program
        Faster loading (2 times as fast)

If you then extend this idea you can do 4,6 and 8 up.

If you can get into bed with the pcb manufacturer you can also avoid post
routing / break off.

The carrier design especially board registration) becomes fairly critical
but in Europe this is very popular, and is becoming more so in USA.

A small picture of an 8 up can be seen on
http://www.datumdynamics.com/smt.htm

Please contact myself or Chris Chapman ([log in to unmask](401)
683-5300) if you want any more info.

Regards

Fin

Finlay Buchan
Tel +44 (0)1290 426200
Fax +44 (0)1290 426212
Email [log in to unmask]


Web Page http://www.datumdynamics.com

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Wade Oberle
Sent: Monday, January 18, 1999 3:18 PM
To: [log in to unmask]
Subject: [TN] One more thing on Double side reflow


Andrew,
        One more thing, we use the same alloy of solder paste on both
sides of the board.

There has been one board where we had to build heat resistant pallets to
support the boards and keep the heat from side 1 when reflowing side2.
This was due to the fact that we had many large mass components on both
sides of the board.  The pallets worked great but they cost $150 each
and need periodic repair and are an obstruction to high volume
manufacturing.

Wade Oberle
[log in to unmask]

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