On Fri, 14 Aug 1998, Dhawan, Ashok wrote:

> 1.How many are using immersion gold with barrier under-plating as
> process. What is process spec for finish as immersion gold--I mean
> barrier plating and gold coating.

Electroless nickel of 150~200 microinches is always the barrier between
copper and immersion gold (3~6 microinches). Electroless nickel sould be
100 minimum, another 50 to ensure good performance. Immersion gold is
self limiting up to ~8 microinches.

> 2. If there is a board manufacturer(s), what is trend or percentage of
> users on gold immersion?

Probably 20 % of overall products.

> 3. Anybody like to share the good or bad experience on technet. Can you
> recommend any board manu with good experience on large volume, long time
> troublefree supply of immersion gold finish.

Try Dynamic Circuits Inc in Milpitas, CA. (1831 Tarob Court, Milpitas,
CA95035, 408-263-0940)

> 4. What is advise on electroless vs eletrolytic or anything else wrt
> phosphorus??

Electroless nickel has about 8% of
phosphorus. I donot see the phosphorus content matters a lot. you might
prefer a certain percent of P according to your abssemble requirement.
Technet had this disscussion before but i don't quite remember.

> 5. What are the things I should check while going in for it.

process controll of the line, defect history, SPC of plating thickness,
compatibility of solder mask, etc.

> >
> >
> > Ashok Dhawan P.ENG.
> > Manufacturing Engineering
> > Unisys Canada Inc.
> > 51 Burmac Road
> > Winnipeg R2J4C9
> > CANADA
> > Fone 204-257-9199
> > Fax   204-257-9104
> >

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