Subject: | |
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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 8 Mar 1999 12:44:17 +1100 |
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Hey Phil ; do you imply below : Bob 's actually overseeing the Forum ? ;
and lately comes VERY seldom to rescue (unlike the rest of grandchildren
minding ancients) ?
That would be indeed inexcusable !
Otherwise yo' dead right , daddy ;
I found our chilling bottom (tech feature 'm takin bout here) is just an
expensive (what the heck) stand by ;
See you paul
> ----------
> From: [log in to unmask][SMTP:[log in to unmask]]
> Sent: Friday, 5 March 1999 1:20
> To: [log in to unmask]
> Subject: Re: [TN] double-sided reflow
>
> It actually is the pad mating to lead wetting area that you use. This is
> multiplied by the the number of leads and if the ratio is less than 30
> grams/sq. in. - it won't fall off.
> I've used this formula for years and Bob Willis and I have postulated that
> it
> is far too conservative. Bob has generated some newer calculations that I
> have sworn to review (see Bob, I haven't forgotten). Some have found the
> ratio to be as much as 44 grams/sq in but in this forum, I'd rather be
> conservative.
> In any event, this includes most components - most QFPs, SOP, TSOPS, even
> PBGA
> (lots of surface mating area). PLCCs, too, but I've had mixed luck with
> 84's
> (though 68's are no problema). As Steve pointed out, you must have a
> smooth
> running conveyor on your reflow system - which you want anyway.
> Hey, if you can remove the gluing process, you should. Try this one at
> home,
> kids!
> Phil Zarrow
> SMT Process Consultant
> ITM, Inc.
> Durham, NH USA
> www.ITM-SMT.com
>
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