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 > > > > > > > > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu