Hey Steve and All,

> So when ya'll get through laughing, tell me this, what kind of problems
> can
> occur from trying to wave solder press-fit connectors...besides the
> obvious
> barrel fill issues that come from the design of compliant-pin press fit
> connectors keeping the solder from flowing up the barrel..."No wonder we
> had
> some many solder problems last time.." I was told by a few of rework
> operators here...kept a straight face on that comment too. (These are
> Harting
> press-fits by the way, a kind of triangular spade looking pin that almost
> fills the whole barrel).
>
Bottom line, does the customer expect you to solder these?
Will they reject the boards if you don't solder & rework them?
Can you give the rework guys and gals special instruction not to worry about
it, if appropriate?

If the customer paid me to do the hokey pokey then I'll dance around (and me
without my skates).

> Me in my logic, thinks that since the connectors were pressed in, there's
> got
> to be some slight barrel deformation and/or strain put on the barrel
> walls.
>
Yup.  According to the old, obsolete, MIL-STD-2166, late '84, Compliant pins
are suppose to deform the hole wall between 1.5 and 2 mils; leaving an
average, minimum, Copper thickness of 0.3 mils for a 10 hole sample with no
cracks in the plating.

A z-axis microsection would show you where the barrels are most distressed.
Serious damage might not be evident from the outside or if you pull the pins
out and look down the barrel.  But it doesn't sound like the boards had
trouble in the past - other than costing you more time and money than might
be necessary.

> Now I might entertain wave soldering a press-fit if I got a board in that
> had
> holes way out of spec and the connectors could be almost pushed in with
> your
> hands. But these connectors have good contact throughout the barrel, and
> the
> pins have been deformed (complied) with the barrel as they were
> pressed-in.
>
You're looking for a logical reason not to do it.

> There's a rumor a-foot that some think we should wave them anyway so they
> look like the ones we built before. I think that's almost the stupidest
> reason I've ever heard to do something like that. I wanna know if there's
> anything detrimental to waving these boards with a nice tight press-fit
> already done...I think there is. What do ya'll think?
>
Are we talking tin-lead pins or are they gold plated?  If they're gold that
would be a great reason not to solder them.

Hans

~~~~~~~~
Hans M. Hinners                                 WR-ALC/LYPME Bldg. 640
Materials Engineer                                      380 Second Street,
Suite 104
Manufacturing Eng. Sec.                         Robins AFB GA 31098-1638
912-926-1970 (Voice) 468 - 1970 (DSN)   912-926-7974 (Fax)
mailto:[log in to unmask]

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