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Ken,

How very kind of your supplier. I think that thickness of gold would almost
certainly make your solder joints brittle in the extreme, even if you could
form any. Or are you talking an overall plating thickness including Nickel
or Palladium? ENIG (electroless nickel/immersion gold) is a good finish if
the board is well made, and I've had good results with it so far, but the
plating over the copper should be between 3 and 6 microns of Nickel and
about 1/8th micron (5 microinches) of immersion gold. 30 microns as you can
see is, in comparison, rather hefty.

Regards

Pete Duncan




                    "Chafin, Ken
                    G."                  To:     [log in to unmask]
                    <kgchafin@SWI        cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
                    TCH.COM>             Subject:     [TN] Solder vs Gold Pads on SMT
                    Sent by:
                    TechNet
                    <[log in to unmask]
                    ORG>


                    08/21/01
                    02:30 AM
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We presently use SMT printed wiring boards with 60/40 tin-lead solder
finish
on the pads.

Our PWB supplier has offered to supply our boards with a 30 micron
electroless gold finish on the pads at the same price.

Does anyone have any views on the relative merits of the two finishes?
Solderability?  Durability?  Reliability?

We manufacture electronic control and signaling systems for the rail and
rapid transit industry and our equipment is often in harsh environments.

Thanks for any information on the subject.

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