Bruce, Ryan, et al.
I wasn't saying that 30 microinches of gold would embrittle a solder joint.
Truth is, I didn't know (until now) how much it would take. All I knew was
that too much gold would lead to problems, and it sounded to me like this
fellow to whom I replied believed you could put as much on as you wanted and
never think about it. I wanted to dispel that.
Tim Reeves
PS I am with a board fab-we just don't do our own immersion gold.
> ----------
> From: Misner, Bruce
> Sent: Thursday, March 16, 2000 5:11
> Subject: Re: ??: [TN] Gold Removal
>
> Enough. 30u Inches of Au IS NOT enough to embrittle solder joints. I've
> done
> it on space flight hardware for years in the 1980's and have performed
> every
> test, environmental screen and evaluation imaginable with no detriment and
> have satisfied NASA and the Air Force. Satisfy your QA with an MRB,
> accept
> the boards, send a SCAR to the vendor, save your schedule and save your
> headache for something real. Next Topic.
>
> > ----------
> > From: Paul Klasek[SMTP:[log in to unmask]]
> > Reply To: TechNet E-Mail Forum.;Paul Klasek
> > Sent: Wednesday, March 15, 2000 8:04 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] ??: [TN] Gold Removal
> >
> > Oh, gee, ehm, Ryan, mate, close, not sure if enough :
> > 1
> > Steve's maths ?(sorry Steve, you ARE one of the LEGENDS):
> > "nearly" 75u" = 1.875um (or close enough);
> > is NOT in line with ITRI's recommended 1.5um ceiling :
> > me the coward never had guts to digest even 1um on soldered pads .
> > I'll give you; with latest pad size trends (smaller); you may creep
> touch
> > higher,
> > but i do know if i'd got totally stoned and placed more than 1umAu on
> > specs,
> > my fellow in QA would be after my skin .
> > Besides, Tim 's been just quizzing me where the hell do i squeeze 0.5um
> > from
> > flush;
> > whining bitterly all he gets from his fabs is 0.25um tops on flash .
> > Record i MEASURED on flash was some 0.8um,
> > so i presume it's my turn in Tim's shoes :
> > Where would you get saturation's which throws 75u" on Ni ?
> > Presume only academic maths ?
> >
> > And the bible talks, i think (?) about 4% , not 3,
> > but i won't be making scenes about that one
> > (less is better, almost, hahaha)
> >
> > And NiAu (0.5umAu average = 20u") costs us less than HASL .
> >
> > Getting gold ears from all this off hip traffic ;
> > getting dark here too: Inge : deleted some dozen methaned messages today
> !
> >
> > All in good humor Ryan , ok ?, just let's retain the functionality.
> >
> >
> > Paul
> >
> > -----Original Message-----
> > From: Ryan Grant [mailto:[log in to unmask]]
> > Sent: Thursday, 16 March 2000 10:47
> > To: [log in to unmask]
> > Subject: Re: [TN] ??: [TN] Gold Removal
> >
> >
> > I agree with this. Do the math. If a five mil stencil is used, and the
> > component leads are NOT gold plated, the board gold thickness can reach
> > nearly 75 micro inches before the percentage of gold in the joint
> reaches
> > the magical number of 3%. Below 3%, gold is not shown to induce
> > embrittlement. If you are soldering to BGA balls, there is even more
> Tin
> > to
> > dilute the gold, so the gold thickness can be even thicker. The reason
> > for
> > the 5 to 8 micro inches of gold thickness is, that is the MINIMUM needed
> > to
> > prevent oxidation of the nickel. Thicker gold is more expensive in
> terms
> > of
> > processing and material cost, and it is unnecessary, so why do it?
> >
> > Of course, if I buy a new stereo, and it has a scratch on it, I'll take
> it
> > back. Functionality be damned. Rick can do the same with his boards.
> >
> > Ryan G.
> >
> > > -----Original Message-----
> > > From: Timothy Reeves [SMTP:[log in to unmask]]
> > > Sent: Wednesday, March 15, 2000 3:08 PM
> > > To: [log in to unmask]
> > > Subject: Re: [TN] ??: [TN] Gold Removal
> > >
> > > Does anyone agree with this? I hope not.
> > >
> > > > ----------
> > > > From: Jonathan A Noquil
> > > > Sent: Tuesday, March 14, 2000 15:57
> > > > Subject: Re: ??: [TN] Gold Removal
> > > >
> > > > Higher gold thickness does not affect
> > > > reliability (solderability),
> > >
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