Yeepee ; "some" answers, finally .
Hey Phil : spot on ( this time ) ,[ despite having one of those AKA
wonders with fridge inside ( ersa hotflow )] .
No problems with FR4 stress on 30'C ; keep you posted if we crack a
track or two .
I just tried to be nice (for a change) and throw Brian a bite ; didn't
think he would be an exhibitionist worthy Jack's attention .
When you boost up your neurons (Phil); anybody , please :
what is , and the advantages of this dwell type pastes (no clean only) ?
I use just the standard missionary profiles > up & down , where does the
dwell apply ? Satellites ? Submarines ?
Thanks a lot
Paul Klasek
http://www.resmed.com
PS
If anybody would have any reflection on P&P bulk feeders ; I would
appreciate them .
Thanks again
> ----------
> From: [log in to unmask][SMTP:[log in to unmask]]
> Sent: Friday, 26 June 1998 8:42
> To: [log in to unmask]
> Subject: Re: [TN] intrusive reflow and all
>
> Brian -
>
> Wow, you found me out! I'll come clean. I used to be a writer for the
> Seinfeld show but now, with the show off the air, I go around making
> up
> information about SMT and reflow.
>
> Okay, I'll get off the caffeinated coffee if you'll stop plugging your
> ovens
> on the Technet. Talk about testy, my oh my.
>
> With all due respect to you, the solutions you propose are valid and
> worth
> trying. I frankly think you should keep things generic and not mention
> the
> name and model of your oven in capital letters at every opportunity.
> And I
> never said that it was the only way (read it again, slowly). However,
> I did
> say that differential heating is unnecessary in this application.
> Sorry to
> take the wind out of your convection, but it is.
>
> No I do not work for a reflow manufacturer. I did at one time work
> for
> Vitronics as Reflow Product Manager for 7 years. By coincidence, did
> a bit
> reflow, too. A lot of reflow and a lot of applications, as a matter
> of fact.
> And yes, we did experiment with differential heating. And yes, I did
> a number
> of applications with BGAs and what I described worked as I described
> it -
> without differential heating. I did additional work during my years
> with
> GSS/Array Technology with BGA and intrusive reflow. So gosh - I guess
> I do
> have some first hand experience with SMT and reflow and I might
> actually know
> what I'm talking about (maybe). Sorry to disappoint you.
>
> One line of thought that arose from the work I did in this area is
> that in
> many cases, not only is differential heating not required, but raises
> questions regarding stresses on the substrate laminate. Think about
> it, if
> you are creating a 30 - 40 deg C difference between two portions of
> the
> laminate, typically .063" apart, what is this doing in terms of
> stress? Now
> here's an experiment for ETS (or someone else to undertake)!
>
> In my work as a consultant (oh god, one of those) I regularly am
> called upon
> by both end users and equipment manufacturers to benchmark test their
> eqiupment for them. Over the years I have tested most of the major
> offerings
> from HELLER, ELECTROVERT, ERSA, RESEARCH, VITRONICS, SOLTEC, BTU,
> SMTECH and
> CONCEPTRONIC (touche'). Many of these manufacturers have also
> developed
> differential heating -some work better than others. I respect the
> fact that
> these companies and ETS have spent big bucks in R&D to develop this
> capability. I question if it is really needed. Most likley, it is an
> attempt
> to create a market differentiator for a product area that is viewed by
> the
> industry at large as a commodity. This is sad as well, because as you
> know
> from your experience with ovens, not all reflow ovens are created
> equal. The
> process may likely be viewed as a commodity but the equipment should
> be less
> so.
>
> Keep on experimenting Brian and keep on inputting into the Technet.
> But please
> keep it generic (or we'll have to sic Capn' Jack on you). I'm going
> to have
> that cup of decaf now, thanks.
>
> Phil Zarrow
> ITM, Inc.
>
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