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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