Daan

I would have thought exactly the opposite! An uneven HASL surface will
have fewer contact points to the aluminium than a flat ENIG surface.
That having been said, I would have thought that both would be bad,
electrochemically speaking, if subjected to humidity. From very poor
memory, the Al-Au couple is somewhere about 4 V, roughly double that of
Al-Sn/Pb.

Brian

d. terstegge wrote:
> Hi Technet,
>
> We are in the process of converting some of our boarddesigns from HASL
> to ENIG conductor finishing. Now one of our designers is worried about
> the effect that this change may have on heat transfer from the plated
> board-edges to the aluminium casing on which the board is mounted. He
> feels that the heattransfer from leadtin to aluminium is better that for
> nickel/gold to aluminium, possibly resulting in heat problems in the end
> product.
>
> Any ideas on this ?
>
> Daan Terstegge
> Thales Communications
> Unclassified mail
> Personal Website: http://www.smtinfo.net
>
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