I appreciate all of the input from the list. I have discovered one thing upon further probing with a hand held DMM. As I mentioned previously I have several DC power supplies that are routed to the board as well (+24V, -24V, +5V, +12V, -12V). When I measure resistance between these DC traces and the trace to the MOSFET drain pin, I am observing between 10M-ohm to 50M-ohm. There is supposed to be no physical path between the digital and drain pin traces. This connection between the 2 appears capacitive because I can watch the resistance on the meter rise and then ultimately go infinite (open circuit). =20 Also, I don't believe that I am dealing with contamination, since this is repeatable on 2 of the same boards that were manufactured 6 months apart. Thanks, Chris -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ed Sayre III Sent: Wednesday, April 20, 2005 1:13 PM To: Jakubiec Christopher (IFNA AI QM CM) Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: PCB Leakage Currents Chris, I saw something like this when I was a test engineer . My experience lead back to the fabrication of the board in the socket area. If the=20 clearance is not large enough sometimes the etch does not remove all the copper. The leakage path is usually lateral along the board surface or=20 between the PCB layers. That being said, Have you looked at an unpopulated board? 200nA may be=20 component leakage? I would recommend you look at all the components on the=20 board and make sure that you do not have a leakage path though them. Also=20 if that does not work, try thermally imagining the board, the area of=20 leakage will show up as warmer then the rest. Good luck -Ed Sayre At 08:55 AM 4/20/2005 -0700, Christopher.Jakubiec@xxxxxxxxxxxx wrote: >All, > >I am currently working with a PCB DUT board that interfaces to an ATE=20 >(tester). I am using this board along with a single socket to measure=20 >power MOSFET DC characteristics. The PCB is a simple 4 layer board=20 >that routes the force/sense resources of the tester to the MOSFET=20 >socket. I currently do not know the exact layer stackup of the board=20 >since I merely created the schematic, and the layout was done=20 >elsewhere. I do know that there are a set of force and sense traces on >the board for 5 individual tester resources. 1 resource connects to=20 >the gate, 3 resources to the drain, & 1 resource to the source(source=20 >is also tied to ground). There are also some digital traces on the=20 >board that bring digital power for the EEPROM and the relays, and these >have tantalum and electrolytic capacitors included. Everything on the=20 >board, analog and digital are using 1 single point ground. > >My problem is when I am trying to measure off-state leakage from drain=20 >to source of the MOSFET (Vgs =3D3D 0V, Vds =3D3D 55V), I measure >200nA = of=20 >current before I even put the device in the socket. When I repeat the=20 >measurement with a blank PCB board I measure 20nA, so I don't believe=20 >that it is coming from the tester or cables. The tester resource that=20 >I am using for the measurement has accuracy & resolution <100pA. Any=20 >ideas of where this 200nA leakage current may be coming from? > >Thanks, > >Chris >Infineon Technologies >------------------------------------------------------------------ >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:=20 >//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 > > > >!DSPAM:42667c3d13632044678054! ------------------------------------------------------------------ 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: =20 //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 =20 ------------------------------------------------------------------ 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