----- Original Message -----
From: "tony steinke" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, April 26, 2002 8:21 AM
Subject: Re: [TN] Immersion Gold Vs Immersion Tin for 0201 landpatterns


> Tuan,
>
> Both processes have their advantages and disadvantages. Both processes
> provide
> a very flat uniformed finish surface. You mention a 12 month shelf life
for
> the Immersion
> Tin, I would say it would be closer to 6-8 months(also the tin does not
> perform well in
> multiple pass assembly) You should check the technet archives and it will
> give you more information
> than you can imagine.
> ----- Original Message -----
> From: "Tuan Bui" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, April 25, 2002 10:07 AM
> Subject: [TN] Immersion Gold Vs Immersion Tin for 0201 landpatterns
>
>
> > Hello Technetters,
> >
> > I'm a new member to this board, and hope some technetters could void
their
> > opinions and advices on this issues.
> >
> > We are currently dealing with a 0201 SMT process and have some issues
with
> > a HASL 0201 landpatterns. The HASL PCB has non-uniformed finshed
surface,
> > and results in tombstones and solderballs after the reflow process. We
> then
> > switch to Immersion gold 0201 landpatterns and the issues of solderballs
> > and tombstones went away. The average cost different between HASl and
> > Immersion gold (7-10 micron)is about 6 - 8 % in cost. Another PCB vendor
> > introduced us to Immersion Tin (white tin) to reduce the additional cost
> of
> > Immersion Gold pads (about 2-5 % cost different between HASl and Tin).
We
> > have used Immersion Gold in many of our prototype products and having
> > really high yeilds, but we have not try the Immersion Tin pad finished
and
> > wonder if they behave like the Immersion Gold. The vendor also mentioned
> > that the Tin finished will oxidize and have a shelf life of 12 months.
> >
> > BTW, We are using "No Clean" process with Convection air oven.
> >
> > Any technetter has experienced in both pads surface finished ( Gold Vs
> Tin)
> > is greatly appreciates.
> >
> > Tuan Bui
> > Process Dev Eng
> > Conexant Systems Inc.
> >
>
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>
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>

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