Steve,

Pretinning while still in the leadframe isn't very difficult. RMA works fine for this. Normally you will only have some bridging in the part that you cut off anyway (and otherwise dip a second time to get rid of the bridges).  After pretinning it is possible to clean the flux off without damaging the leads. Your pick & place machine will like that.
Only drawback is that some solder will be scraped of the leads, which contaminates the tooling (more maintenance). 

Daan Terstegge
Unclassified mail

>>> "Stephen R. Gregory" <[log in to unmask]> 09/29 12:34 am >>>
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?

Thanks!

-Steve Gregory-

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