[SI-LIST] Re: Sanmina patent on dielectric thicknesses under 4 mils

Ron,
May I ask what is the intend use for the sub nf caps ?

By no means I claim there is absolutely no need for sub-nf caps,
however, I always question the need for sub-nf caps for EMI or
noise decoupling in a digital system. I believe the place for
such decoupling is either on die or package not on the PCB. 
In fear of sounding like a broken record again, I claimed :
a) High frequency core noise cannot propagation through the
package back to the PCB. Same reason you have sso limitation 
on a package, its just as bad to go out of than go into a 
package. Core noise above 100MHz can not be decoupled 
outside the package.
b) I/O switching noise is related to the image current 
return path which exist between the power plane sandwiching
the signal layers and dictated by the impedance control
of the stackup.

I've used Zycon before thinking they can lower EMI or 
power noise but the reality is they don't and the reasons
are stated above.

If you have other reasons to use distributed sub nf 
decoupling caps, I will keep by mouth shut. And I practice
what I preach. I never use decoupling below 1nf in any of 
my systems and they pass class B just fine.



-----Original Message-----
From: Ron Miller [mailto:rmiller@xxxxxxxxxxx]
Sent: Tuesday, November 27, 2001 10:36 AM
To: si-list@xxxxxxxxxxxxx; rfmeas@xxxxxxxxxxxxxxxxxxxxxxx
Subject: [SI-LIST] Sanmina patent on dielectric thicknesses under 4 mils


Hi Guys

I am up against the problem of using thinner dielectric in order to
eliminate the need for sub-1000 pf bypass capacitors.

While this technique was used for many years some idiot at the patent
office actually gave them a patent for it.  No novelty at all but
standard practice.

Is anyone else having trouble with this?

Does anyone have published articles or books that document this use prior
to 1989?

If so, please let me know.  Perhaps a consortium of industry professionals
can help to remove this travesty of the patent system.

Ron Miller
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