Hi Jack

I have some question about the flash or immersion good.

As I my mind, The flash gold is electrolyic plated. The immersion gold is just
coat by chemically reaction. Is that right?
So ENIG is refer to immersion gold.... E refer to electroless.

More, can u point out the pros or cons between them.


Best Regard,
Nicholas Lai
10/9/99





Eric Yakobson <[log in to unmask]> on 99/10/09 08:55:10 AM

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cc:    (bcc: Nicholas LAI/CS/Topsearch)

Subject:  Re: [TN] Flash Gold vs. ???



Hi Jack,

Unfortunately plating terminology is not much less confusing then the one for
Solder Float-Stress-Shock Testing.

The term soft gold refers to high purity 24K (usually electroplated) gold, as
opposed to hard gold, which contains Ni and/or Co.  Terms flash or strike
usually refer to thin deposits.  Strike traditionally is applied as a thin
electrolytic deposit out of diluted (low metal concentration) bath -- for better
throw and coverage -- in order to improve adhesion of the substrate to
subsequent electrolytic deposit, whereas flash is be applied as a thin final
coating, e.g. to impart a certain color to the substrate (jewelry).

Immersion gold, as you rightly pointed out , is inherently self-limiting (<10-12
microinches -- not mils!) and high-purity, therefore it technically can be
called "soft" and "flash".  If it is "any thickness you want" -- it's not
immersion and it can't be called "flash".  It's either electroless (more precise
term is autocatalytic, since technically immersion also belongs to electroless
class), or deep (heavy) electrolytic.

Hope I didn't confuse you even more.

Eric Yakobson
Alpha PC Fab







Jack Olson <[log in to unmask]> on 10/07/99 08:34:03 AM

To:   [log in to unmask]
cc:    (bcc: Eric Yakobson/AlphaPCFabUS/Cookson)
Subject:  [TN] Flash Gold vs. ???




Do some manufacturers use the soft electroless gold (deep bath?) in place of
immersion gold? Is there some place I could learn what the difference is?
None of my books address it, and I always thought flash gold was a
self-limiting process that wouldn't go over 10 mils, but now we are hearing
it can be any thickness we want. True?

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