Thanks for the informative reply. I'm confident you are correct on the
micro "inches" issue.
Most of our boards do have gold fingers but we have that specified
adequately I think.
Thanks again.
> -----Original Message-----
> From: Roger M. Stoops [SMTP:[log in to unmask]]
> Sent: Monday, August 20, 2001 3:14 PM
> To: [log in to unmask]
> Subject: Re: [TN] Solder vs Gold Pads on SMT
>
> Ken,
> There exists in the TechNet archives lots of info about ENIG (electroless
> nickel/immersion gold) and the pros and cons of using such. There seems
> to
> be some debate about its use with BGAs, but for the most part many find
> ENIG acceptable. We have been getting some boards from a fab house with
> ENIG, with no problems so far, with the possibility of using ENIG in the
> future for new products.
> Solderability is excellent, durability is good, reliability is good. The
> gold finish provides a basically oxide-free surface, to allow good wetting
> to the nickel plating underneath. Solder embrittlement becomes an issue
> with heavy gold plating. (Of course, HP has been using ENIG on their
> boards for years. Saw that even 24 years ago with an inexpensive 3-1/2
> digit DVM from HP: an Au-plated board. Made all the techs at now-defunct
> company jealous...)
> Would this board supplier be in Canada, per chance?
> BTW, I think you meant to say 30 micro-inch electroless gold finish. 1
> micron = 1 micrometer = 39.4 micro-inches. Just a thought: if you are
> not
> using edge-fingers (probably not, considering the end use), you might be
> just as well off with 4 to 10 micro-inches of Au over 100uin of Nickel.
> Roger M. Stoops, C.I.D., PCB Designer
>
>
> Trimble
> Engineering and Construction Division
> 5475 Kellenburger Rd.
> Dayton, OH 45424-1099 USA
> Ph: +01 937.233.8921 or +01 937.233.4574 ext 288
> Fax: +01 937.233.7511
>
>
>
>
>
>
> "Chafin, Ken
> G." To: [log in to unmask]
> <kgchafin@SWI cc:
> TCH.COM> Subject: [TN] Solder vs Gold
> Pads on SMT
> Sent by:
> TechNet
> <[log in to unmask]
> ORG>
>
>
> 08/20/01
> 02:30 PM
> 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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