Silver oxides are electrically conductive, one of the reasons why they
are used commonly in electrically conductive adhesives. No, it's the
solder which oxidises and gives rise to problems. In addition, there are
problems with the adhesion of typical Ag epoxies with Sn/Pb solder.
Peter
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Peter Swanson [log in to unmask]
INTERTRONICS http://www.intertronics.co.uk
INTERTRONICS is dedicated to providing quality material,
consumable and equipment solutions to the electronics
manufacturing and other technology based industries, with
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service.
-----Original Message-----
From: Marsico, James [mailto:[log in to unmask]]
Sent: 24 January 2001 18:28
To: [log in to unmask]
Subject: Re: [TN] silver epoxy & solder coated parts
Hi Glenn,
Thanks for your response. One more question... I'm assuming that the
increase in resistance is due to oxidation of the silver at the
epoxy/solder
interface. If this is true, then why wouldn't oxidation occur with a
Pd/Ag
finish?
Thanks again,
Jim Marsico
EDO Electronic Systems Group
[log in to unmask] <mailto:[log in to unmask]>
-----Original Message-----
From: Pelkey, Glenn [SMTP:[log in to unmask]]
Sent: Wednesday, January 24, 2001 12:18 PM
To: [log in to unmask]
Subject: Re: [TN] silver epoxy & solder coated parts
Hi Jim,
We've performed some accelerated tests on this
combination.
Testing
showed increase in resistance and decrease in adhesion. Initial
adhesion
was even poorer than the other combinations.
Our recommendation was solder terminated components
should
be
soldered, Pd/Ag terminated should be epoxied. I've heard others
say
you can
solder Pd/Ag terminated caps, but the process window is tight
and no
rework
is allowed. My opinion is not to do it, not worth the risk.
As for acceleration, will it last 2 years in your
environment? I
don't think so, but I'm just guessing. Six months, probably.
The
acceleration model I have would need more data from temperature
and
humidity
factors. Don't forget the mechanical shock.
Have you talked to CALCE? http://www.calce.umd.edu/
Glenn
> -----Original Message-----
> From: Marsico, James [SMTP:[log in to unmask]]
> Sent: Tuesday, January 23, 2001 12:35 PM
> To: [log in to unmask]
> Subject: [TN] silver epoxy & solder coated parts
>
> Hello, Technet...
>
> Here is an unusual situation. We have to assemble a surface
mount
> assembly
> using silver epoxy. Some of the components will be solder
coated.
I
> know,
> don't bother asking... this is the way it has to be. The good
thing is
> that
> this assembly is a prototype for bench-top laboratory use
only.
There is
> no
> harsh environment and needs to operate 1, maybe 2, years. The
question is
> does anyone foresee any problems? What happens when one mixes
toe
two
> technologies?
>
> Thanks,
> Jim Marsico
> EDO Electronic Systems Group
> [log in to unmask] <mailto:[log in to unmask]>
>
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