Paul,
What is a paste sheet?

regards,
Bev Christian

> -----Original Message-----
> From: Paul Klasek [SMTP:[log in to unmask]]
> Sent: Wednesday, September 29, 1999 7:34 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] Pre-Tinning Fine Pitch...
>
> Not bad idea if the extra heat cycle is (should be) tolerable, Dave .
> Maybe Steve also could dip them in paste sheet ; flip upside(legs up)down
> on
> pallet (keeping cooler as well);
> in theory all the paste should wick evenly in reflow (dispensing indium
> does).
> Practically I prefer miniwave still ; with vacuum pick up handling it's
> clean and easy.
> Also the flux dip is reassuring with sus finish .
> Still again , the reflow would give more even result ; have to try this
> one
> ; you may have a point
>
> paul
>
> -----Original Message-----
> From: David Hillman [mailto:[log in to unmask]]
> Sent: Wednesday, 29 September 1999 23:17
> To: [log in to unmask]
> Subject: Re: [TN] Pre-Tinning Fine Pitch...
>
>
> Hi Steve! It still amazes me that we are a industry dominated by surface
> mount
> technology but we tend to think in wave soldering terms! One option you
> might
> try is to use your reflow ovens for tinning - stencil print the component
> footprint on a nonwettable substrate (e.g. ptfe or stainless steel), use
> your
> placement options (manually or automatically) to place the parts on the
> solderpaste deposit, and then run them thru the oven. This works quite
> well
> but
> can be problematic in the placement step. And if you don't want to make a
> stencil, you can hand apply the solder paste on the leads manually. Good
> Luck.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
>
> "Stephen R. Gregory" <[log in to unmask]> on 09/28/99 06:34:38 PM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
> respond
> to
>       [log in to unmask]
>
> To:   [log in to unmask]
> cc:
>
> Subject:  [TN] Pre-Tinning Fine Pitch...
>
>
>
> Hi ya'll!
>
> Boy, I may have quite a task ahead of me. There's this assembly that has
> hit
> the floor that has just about every part (CQFP's and ceramic SOIC's) in
> the
> un-formed state, and we've got to form and trim, then Pre-tin the gold
> plated
> stuff. I've already got a call into Six Sigma to get a quote on doing this
> stuff for me, but it may turn-out that we won't have the time to deal with
> this build and sub-contracting the forming and trimming, and pre-tinning
> out
> (what's new?).
>
> But in case I have to pre-tin the CQFP's myself, are there any tips that
> anyone can share to help me get through this as painlessly as possible?
> These
> parts are 320-pin 25-mil pitch and still have the tie-bars attached. I've
> got
> a bottle of nitrogen and plan to "Rube-Goldberg" me an enclosure to
> blanket
> the pot with nitrogen over the tinning pot that I'll be using...I think
> that'll help to cut down on the bridging I'll see. I'm going to use an RMA
> flux as well...any other suggestions? PLEASE?
>
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