True , works up to an extend, nasty way to treat cold barrels (Werner must
have an opinion on this),
also the double burn 's got a hard work to come up on exhausted flux as
Zoran pointed out.
Still say it's easier to wick a lot of flux from foam ,
than deflecting spray all over but the deep barrel.

Overall possibly less damaging than 5 min IR fry, have to admit using prime
wave for heating myself,
not exactly what chip double was designed for .

Secondary foamer is easy to rig, may try that as well .
paul

-----Original Message-----
From: Ed Popielarski [mailto:[log in to unmask]]
Sent: Friday, 11 August 2000 9:46
To: [log in to unmask]
Subject: Re: [TN] Topside solder fillets after wave...


Steve,

I ran across the exact same thing trying to solder a 24" x 24" Kollmorgen
Mutiwire .100 thick with lots of 2oz ground planes and lots of PGA's.

I went out and rented (at a fairly steep price in the mid 80's) an IR
thermography system and watched those puppies go through the process while I
modified the parameters (one at a time, of course) and the most significant
effect was observed in the wave. So, being the cavalier "damned the
torpedoes" kinda guy, I tried turning on the chip wave and speeding up the
conveyor a bit. Lo an' behold... it worked, and I have the video to prove
it!

Seems "bumping" the thermal mass with the chip wave followed by the
"equillibrium time" in transit to the smooth wave was enough of a boost to
overcome the ground plane sink effect.

Using the video I finally convinced Design Engineering to evaluate some
enhancements for ground plane thermal relief patterns. This would only work
if you have design control over the PCB, tho.

Let me know if it works!


Ed Popielarski
QTA Machine
10 Mc Laren, Ste. D
Irvine, Ca. 92618

Ph: 949-581-6601
Fx: 949-581-2448

http://www.qta.net <http://www.qta.net>

Check out our BGA Baller and Process Equipment Services!

##############################################################
TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################