Hi Bev,
I see a lot a technical definitions. I have will offer my interpretation of
this test with respect to the intent as I understand it.
I have always understood that the "surface" part of the SIR was directed
toward the resistance or conversely the conductivity of any contamination
which may remain on the surface of the insulting material or perhaps even
on the surface of the laminate or other substrate the insulating material my
be covering. Typically, the majority of insulating materials such as
soldermask do not have insulation issues. However, the surface or subsurface
elements ( i.e.. flux residue, salts, etc...) have and do create insulation
issues between devices if not cleaned properly.
I could be wrong, but that is just my opinion,
Ed Cosper
ABC
----- Original Message -----
From: "Bev Christian" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, April 27, 2001 11:17 AM
Subject: [TN] SIR Definition
> OK, let's see what I can stir up today. :)
>
> I am looking for a clear, succinct definition of surface insulation
> resistance. If I look in IPC-9201 "Surface Insulation Resistance
Handbook",
> I don't find what I am looking for. (Sorry, Joe, Doug et al). What I find
> on page 2, section 2.1, Definitions is the following: "It represents the
> electrical resistance between two electrical conductors separated by some
> dielectric material(s). This property is loosely based on the concept of
> sheet resistance, (see ASTM-D-263), but also contains elements of bulk
> conductivity, leakage through electrolytic contaminants, multiple
dielectric
> and metallization materials and air." Whew!
>
> Any takers? Hmmm?
>
> regards,
> Bev Christian
> Research in Motion
>
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