Why it is sometimes necessary to re-seat a board or chip

dwight elvey dkelvey at hotmail.com
Wed Dec 31 09:01:10 CST 2008




----------------------------------------
> From: cclist at sydex.com
>
> On 30 Dec 2008 at 22:41, dwight elvey wrote:
>
>> To my knowledge, it is pure gold. It is difficult to plate
>> alloys.
>
> Not really that hard, depending on the alloy. For instance, I can
> plate brass in my own shop--it's not difficult; just an acid bath
> process. (Tin-lead) Solder has been electroplated onto PCBs for
> decades.
>
> Some people have pointed to their college chemistry texts and told me
> definitively that it was impossible to electrodeposit an alloy. I
> don't know where that one got started.
>
> I'll agree that cooking up a plating bath can be a black art. Stuff
> you'd never think would affect the outcome such as sugar sometimes
> winds up in them and I know a retired fellow who ran a plating shop
> who swore that he got better results than anyone else because he
> urinated in his tanks.
>
> From: http://www.pfonline.com/articles/pfd0022.html
>
> Hard, Bright Gold
>
> Platers who gold plate contacts and connectors generally use bright
> acid gold formulations. These baths contain complexed cobalt or
> nickel in small quantities, to improve hardness and brightness of the
> deposit. Such gold electroplates will be 99.7 to 99.9 pct pure, and
> hardness can be 120 to 300 Knoop. The small amount of nickel or
> cobalt will interfere with die bonding, so these baths cannot be used
> for semiconductor plating. Hard, bright gold baths, if operated with
> good housekeeping and chemical control, have very long life-often
> three years and more.
>
> Cheers,
> Chuck

Hi Chuck
 I only meant that is wasn't 18K gold and not that is was impossible.
speed is important, as mentioned in the article you point to.
It is harden some but it is still quite close to 24K.
Dwight
 
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