Anil
I'm sorry, but I cannot agree. Nickel is not a sustainable solution.
1) By itself, nickel is poorly solderable because it has a thin oxide
film which requires a strong, halide-containing, flux to penetrate. This
implies cleaning being a probable requirement.
2) The purpose of the gold flash is to try to prevent that oxide film
from forming. All such gold flashes, whether electrolytic or
electroless, are more or less porous, so their effectiveness is limited
in time, without 1) above becoming valid, even with the gold flash.
3) In an intermediate stage, before soldering becomes visibly
problematic, isolated points of nickel may oxidise. This will cause
dewetting which may not be very visible (except for wave soldering), but
may weaken the solder joint.
4) The minimum electrochemical potential between gold and nickel is 1.67
volts, so, under humid and ionic conditions, the possibility of severe
corrosion is great.
5) Nickel salts are known to be carcinogenic and require great care in
handling during the plating operations. Are all plating shops equipped
with the personal protection equipment required for such caution????
Brian
> Anil Kher wrote:
>
> Dear Earl
>
> Good ductile additive/P free Nickel base covered by a flash ~
> 0.05 microns of Gold should provide a very cost effective finish
> competeitive with HASL and others.
>
> The key component for solderability and shelf life is the Nickel
> undercoat.
> ~ 5 microns is adequate if ductile etc as above.
>
> Under proper controlled condition this finish should give all
> advantages as
> 1. Longer shelf life - ( Nickel is critical.)
> 2. Flat surface profile
>
> what more - economic and looks good too.
>
> Anil Kher
>
>
>
> micro interconnexion pvt. ltd.
> D3-12 A , Corlim Industrial Estate , Corlim , Ilhas , Goa , India –
> 40311
> Tel : 00-91-832-284209 / 284337. Fax : 00-91-832-284209 / 285271.
> E-mail :- [log in to unmask]
> LEADERS IN GOLD PLATED PCBS
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