You might want to add a little about gold plating.  Gold in itself does
NOT bond to solder.  It does, however, protect against oxidation.  The
gold plating has to be very thin, on the order of 2 - 3 micros.  The
solder actually goes through the gold to bond to the surface underneath.
If the gold layer is too thick, the components will just fall off.  We
had a board house plate the pads with a thicker layer used with edge
connectors, and most of the components just fell off.  You have to be
very careful with the process.
Art

> -----Original Message-----
> From: Albert Mok [SMTP:[log in to unmask]]
> Sent: Wednesday, April 28, 1999 7:40 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Flash Gold??
>
> Dear technetters,
>
> We regard "flash gold"for gold thickness up to 2 microinch.  The
> purpose of
> gold flash is to give protection of nickel against oxidation and also
> provide better solderability when compared with bare nickel.  Flasg
> gold is
> very common for COB boards and the whole board will be electroplated
> for
> maximum 2 microinch.
>
> _____________________________________________________________
>
>
> At 06:58 AM 1999/4/27 -0700, David McCann wrote:
> >We have used flash gold on rigid flex products to maintain a
> solderable
> >surface.  Typically I have seen approximately 4 microinches of Au (ie
> flash
> >Au referring to a very thin electroless plating), over 100
> microinches
> >minimum of electroless Ni over Cu.
> >
> >Regards,
> >
> >-----Original Message-----
> >From: TechNet [mailto:[log in to unmask]]On Behalf Of Nick Liang
> >Sent: Monday, April 26, 1999 11:41 PM
> >To: [log in to unmask]
> >Subject: [TN] Flash Gold??
> >
> >
> >All:
> >What is Flash Gold Process??
> >
> >Thanks for your answers.
> >
> >-----------------------------------------------
> >Nick Liang
> >QE Engineer
> >Quality Assurance Division
> >Gold Circuit Electronics Ltd.
> >Tel : (886) 03-4612541 Ext 417
> >Fax: (886) 03-4522094
> >Cell: (886) 0935-917151
> >E-Mail : [log in to unmask]
> >------------------------------------------------
> >
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