Bob:
Did you do any testing to the bare such as simulated aging or to the
assembled boards such as temperature/humidity cycling, SMD pull testing,
etc.
Ron
----- Original Message -----
From: Furrow, Robert Gordon (Bob) <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, November 06, 2000 10:19 AM
Subject: Re: [TN] IMMERSION SILVER SURFACE FINISH
> Jim,
>
> We have utilized immersion silver as a PWB surface finish on a large
> quantity of boards for the past few years. Our experience has been
excellent
> and it is now the preferred finish at some of our manufacturing locations.
> George Wenger of our research center and I submitted a paper which he
> presented that detailed our qualification and experience (up to that
point)
> at the September 1999 IPC Surface Finish Forum. Since then we have
qualified
> several PWB shops for this use and have qualified another chemistry
vendor's
> process. We have found if stored properly, the finish retains excellent
> solderability for over a year. It handles multiple thermal excursions well
> and has superior hole fill characteristics compared to OSP's. We did see a
> few start-up issues with our initial board vendor, but since then things
> have gone smoothly. To date, I have seen two relatively minor assembly
> issues. The first is that the surface will darken if exposed to sulfur.
The
> solderability remains good, but cosmetically it was very noticeable. This
> became evident at one location when after the first side surface mount
> operation, boards were placed onto an ESD mat that had a high sulfur
> content. Switching to a new type of mat resolved this issue. The second
> issue is pin contact at ICT. If you are not wave soldering or if you
> selectively wave solder, then some of the test pins may contact silver
> coated pads. If your test fixtures are set up to handle OSP coated boards
I
> would expect no issues, but if they have only tested to solder previously,
> there might be a need to either change probe types or optimize the
fixture.
> As far as cost is concerned I would expect it to be between the cost of an
> OSP coated board and that of a HASL finish. If you would like further
> information please contact me.
>
> Thanks,
> Robert Furrow
> SMT Process Engineer
> Lucent Technologies
> 978-960-3224 [log in to unmask]
>
> > -----Original Message-----
> > From: Jim McMurry [SMTP:[log in to unmask]]
> > Sent: Monday, November 06, 2000 9:05 AM
> > To: [log in to unmask]
> > Subject: [TN] IMMERSION SILVER SURFACE FINISH
> >
> > Jim McMurry@PATAPSCO
> > 11/06/2000 09:05 AM
> >
> > I am interested in hereing from anyone who may be using or may have used
> > immersion silver finish on production or prototype pcb's. I would like
to
> > know
> > the good and bad sides of this finish. If there are any information
> > resources
> > available on the subject. Are there any cost comparisons?
> >
> > Thank you all for your time and response.
> >
>
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