Ow, ye, 'f cause Joyce, quite common boost, usually not full blast as base
heater.
Usually in high speed lines.
Makes little heat impact with 1/8 laminates, mind you ,
but it keeps bow much lower with expanding upper copper > especially with
1/8's!
Used to have one as a sandwich (top above base, less than half heat -
depends).
Good point for Steve, forgot this one
(loosing it, did i say i miss the contract sugar?).
pk
-----Original Message-----
From: joyce [mailto:[log in to unmask]]
Sent: Friday, 11 August 2000 19:59
To: Paul Klasek
Subject: Re: [TN] Topside solder fillets after wave...
Paul, just a thought of it...Is it possible to put an IR preheat on top
(provide you don't have tall electrolytic cap type shadow...)just before hit
the wave? of course you don't want to let the designer know about
it...otherwise, they will crack out more "challenge" design...
jk
At 03:11 PM 8/11/00 +1000, you wrote:
>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
>##############################################################
>
##############################################################
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
##############################################################
|
