Yes, nice idea! But how do you get maximum support on a complex
     assembly for the printer without it creating massive heat sinking
     scenarios which ruin the thermal characterisics of the assembly with
     regard to reflow.
     I believe the two are in opposition to each other. Printing requires
     large mass in the support with as much contact under the board to give
     adequate support. Reflow requires pallets which have as little contact
     with the assembly underside as possible, thereby NOT sinking heat from
     the upper side reflow.
     I have designed alot of jigs for such purposes, and don't agree with
     putting the two aspects together.
     Regards

        Edward Brunker
     Senior Process Engineer


______________________________ Reply Separator _________________________________
Subject: Re: [TN] One more thing on Double side reflow
Author:  <[log in to unmask]> at INTERNET
Date:    19/01/99 12:06


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]

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section
for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text
n the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for
ditional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700
t.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################