We do a lot of work requiring EMI sealing on unite with Iridided aluminum housings, if
proper materials are used (to avoid galvonic corrosion) it works great.  But the
Iridite coating is soft and in an application requiring a rotary interface the coating
would wear off very rapidly.  If possible you may want to look into nickel plating the
wear surface to eliminate this problem.

"Louis, Edwin @ CSE" wrote:

> Do you know of an appropriate EMI material for a rotary seal, where one
> mside of the seal rotates against the seal? What is your experience with an
> EMI seal interfacing with conductive
> Iridited(Chromate conversion coating)on Aluminum?
>
> -----Original Message-----
> From: Misner, Bruce [mailto:[log in to unmask]]
> Sent: Wednesday, July 26, 2000 9:35 AM
> To: [log in to unmask]
> Subject: Re: [TN] Plugging Vias With Conductive Epoxy
>
> Hans,
>
> All the experiments (extensive) and experiences (20 years of use with the
> high purity types; I'm not associated with the epoxy manufacturers) I have
> run with Silver filled epoxies has shown them to  work well in a compressed
> state sandwiched between 2 surfaces with compatible finishes (typically
> noble metals) in low current applications.
>
> They will experience higher and somewhat varying resistance's when used to
> bridge gaps and fill voids (read that as unreliable) like a PTH. I have
> found these resistance's to typically be small (usually less than a few
> ohms, often in the milliohm range) but can, of course, be detrimental to
> some critical electrical performance.  I would also question the
> compatibility with White Tin and would not be surprised if that interface
> further contributes to varying (increasing) resistance over time and temp,
> but you would need to perform that experiment for yourself. Use in a PTH for
> continuity test purposes may be fine but could also mask a barrel plating
> problem until the resistance goes up over time and temp.
>
> Regards,
> Bruce Misner
>
> > ----------
> > From:         Hans Rohr[SMTP:[log in to unmask]]
> > Reply To:     TechNet E-Mail Forum.;Hans Rohr
> > Sent:         Tuesday, July 25, 2000 9:10 PM
> > To:   [log in to unmask]
> > Subject:      [TN] Plugging Vias With Conductive Epoxy
> >
> > One of our customers wants us to plug vias (.016-.020") with a
> > conductive epoxy material.  The board is finished with white tin so
> > plugging with solder is out. The vias do not have to be completely
> > filled but the plugs must be strong enough to withstand test probe
> > pressure.  The epoxy filled vias will be used as test points.  We have
> > used carbon and silver epoxy on conductive surfaces but never to plug
> > holes.  Has anyone ever done this and can you suggest a conductive epoxy
> > that can be screened on?
> >
> > Hans Rohr
> >
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