FreeLists / si-list / [SI-LIST] Re: volume resistivity (or conductivity) of printed circuit boards

[Dimiter Popoff <dp@xxxxxxxxxxx>]

Jan Vercammen,

the 1e9 to 1e11 values seem too conservative for FR-4 to me,
the real figures must be much better.
I have no spec in front of me to refer to, but I know from
experience that there are no leackage issues when I use
a 1GOhm feedback resistor for my up to 5 kV HV sources.
Provided the board is clean, of course - and I have not
tried those water-soluble fluxes (nor do I think I ever
will after all the leackage horror stories I have heard...).


Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------


> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] volume resistivity (or conductivity) of printed circuit 
> boards
> From: jan.vercammen1@xxxxxxxx
> Date: Mon, 2 May 2005 12:04:40 +0200
> 
> hello SI-list,
> I am looking for data on the volume resistivity (or conductivity) 
> glass-epoxy (= printed circuit board FR-4)
> materials.
> 
> I have found variuos numbers myself, but I am somewhat uncertain about 
> exact figures. Actually I have a 2D or
> 3D finite -element solver who can take care of realistic packaging and 
> printed track details, but as I stated before,
> the results are only as good as the resistivity values used.
> 
> The resistivity values I find for epoxy (likely without glass) are 1e9 to 
> 1e11 ohm.m (or 1e-9 to 1e-11 S/m).
> 
> I know that water is an important factor.
> 
> We are working on photodetector circuits with estimated impedance of 
> several hundred's of Mohms.
> 
> Can someone help me with the following questions:
> -1- are my volume resistivity values correct?
> -2- does anyone have figures between bone-dry, normal and high humidity 
> conditions
> -3- can I use the same value for the solder mask and what is the effect of 
> the solder mask
> 
> Kind regards,
> 
> Jan vercammen
> 
>
>
>
>
>
>
>

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