Hi Jim,
What our study found was an absence of Tin at the epoxy/solder
interface and concluded that diffusion of the tin into the epoxy took place.
I'm not an expert by any means on diffusion, but we found this through SEM
and EDX.
Glenn
> -----Original Message-----
> From: Marsico, James [SMTP:[log in to unmask]]
> Sent: Wednesday, January 24, 2001 10:28 AM
> To: 'TechNet E-Mail Forum.'; 'Pelkey, Glenn'
> 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]>
> >
>
>
> --------------------------------------------------------------------------
> --
> -----
> Technet Mail List provided as a free service by IPC using LISTSERV
> 1.8d
> To unsubscribe, send a message to [log in to unmask] with following
> text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send the following message:
> SET Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources &
> Databases > E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional
> information, or contact Keach Sasamori at [log in to unmask] or
> 847-509-9700 ext.5315
>
> --------------------------------------------------------------------------
> --
> -----
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
