Phil,

We have an application where we have a coil contact spring which must be
soldered to a brass washer for a High Voltage connection.  Our method of
success was to use stainless steel spring stock and plate it with
electroless nickel.

A side note, we had to switch from BeCu spring stock to stainless steel
because the BeCu was loosing it's spring strength when we were soldering it
to the washer.

Hope this helps.

Phil Nutting
Mfg. Eng.
Kaiser Systems, Inc.


-----Original Message-----
From: Phil Bavaro [mailto:[log in to unmask]]
Sent: Tuesday, June 13, 2000 1:47 PM
To: [log in to unmask]
Subject: [TN] BeCu with bright tin finish solderability


Can someone tell me if there is a better way to call out a solderable
material finish for a simple formed spring finger which is intended to be
soldered using standard solderpaste/reflow processing?  These are very
similar to emi gasketing for doors, but I've never had to solder them down
before.

"Material:  0.003" thick Beryllium copper (BeCu) alloy 25 per ASTM B194.
Finish: Bright Tin per Mil-T-10727."

I don't have a lot of familiarity with either spec and need to know what
the rest of the industry would use in this situation.  I'm a little
concerned about the use of the MIL Spec and also the wetting to the exposed
edges of beryllium copper as the springs will be made in bulk and then
singulated after plating.

These will function as the grounding contact between a board and a chassis.

Thanks,

Phil

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