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Reply To: | TechNet E-Mail Forum. |
Date: | Tue, 21 Aug 2001 08:26:23 -0700 |
Content-Type: | text/plain |
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ken,
Typically 30 micro inches of gold is used only for wire bonding purposes.
I think it is almost impossible to solder to that much gold with out to much gold
leaching into your solder.
Greg Scott
Cray Inc.
> [This e-mail is confidential and may also be privileged. If you are not the
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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
> Please
> respond to
> "TechNet
> E-Mail
> Forum."
>
> 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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