Thanks for the input you guys have given me.
I had heard some of the same things, that the 2% is used in the Hybrid
industry and that the 2% is suppose to give shinier (cosmetic) solder
joints. But, I guess my question is, does the 2% give me a just a better
cosmetic joint? Is there no real mechanical benefit?
Thanks,
Larry
-----Original Message-----
From: d. terstegge [mailto:[log in to unmask]]
Sent: Thursday, July 26, 2001 8:32 AM
To: [log in to unmask]
Subject: Re: [TN] solder paste with 2% silver
From "Soldering in Electronics" by Klein Wassink:
"Note on solder alloy composition:
Solder paste in hybrid circuit technology (for thick-film circuits)
usually has a metal composition of tin62-lead36-silver2. It should be
realised that the addition of silver is not at all necessary for the
silver (-palladium) metallisation of the components, but for the much
thinner silver-palladium conductors on the tick-film substrates. The use
of the more expensive silver containing alloy, instead of the common
tin60-lead40 alloy, for (relow) soldering on printed boards with copper
solder lands is not based on technological necessity, but sometimes on
better availability of this alloy (in the form of paste) and in most
cases merely on habit. For the rest: with silver loaded alloy no harm is
done !"
Kind regards,
Daan Terstegge
SMT Centre
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net
>>> "Kasprzak, Bill (sys) USX" <[log in to unmask]> 07/26 1:54 pm >>>
To all:
I've been reading, with great interest, the responses so far to the use
of
2% silver paste. I am not being critical of the folks who responded so
far
but, each one cites a "reported" or "understood" advantage to using 2%
paste.
I have also heard some of same reasons for considering a switch to a 2%
silver paste. Can any of the metallurgists on this forum confirm some of
these reported advantages and perhaps recommend that given x,y, and z,
one
should consider using 2% silver solder alloys?
Good topic.
Bill Kasprzak
Moog Inc., Electronic Assembly Engineering
> -----Original Message-----
> From: Eric Christison [SMTP:[log in to unmask]]
> Sent: Thursday, July 26, 2001 4:20 AM
> To: [log in to unmask]
> Subject: Re: [TN] solder paste with 2% silver
>
> > I always understood that you had to use a paste with 2% silver if
you
> > were using components
> > with terminations containing Palladium. The 2% silver is also
supposed
> to
> > five you a shinier
> > finished solder joint.
> >
> > Steve.
> >
> > Larry Koens wrote:
> >
> > > Got a question for everyone,
> > >
> > > I just switched companies and the new company that I'm with now
uses a
> > > 62/36/2 solder paste. I've always used the 63/37 formula. The guys
who
> > > decided to use the 2% silver are no longer with the company. My
> > question
> > > to you is, why would they want the 2% silver in the paste? They
know
> > > something I don't?!
> > >
>
> The silver should give the alloy higher strength, better creep
resistance
> and a higher melting point. Perhaps your application benefits from one
of
> these differences?
>
> Regards,
>
>
>
> Eric Christison
>
>
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