From ernie@physics.carleton.ca Thu Sep 18 08:56:42 2003 Date: Mon, 15 Sep 2003 13:37:48 -0400 (EDT) From: Ernie Neuheimer To: Madhu@physics.carleton.ca Cc: Kirsten Sachs Subject: Measurement of Dupont XC Kapton Resistive Film with Applied Voltage Gradient, Part Three. X-IMAPbase: 1426689701 1 Status: O X-Status: X-Keywords: X-UID: 1 Madhu, The foil resistance of the two types of Dupont Kapton carbon-loaded type XC resistive foil which we received on about 14 August were measured vs voltage gradient. The two types were described by James Ochsner of Dupont USA (281-474-8672 or as follows: Sheet #1: 1 x 10E6 Ohms/square at .1V/cm. 3 x 10E5 Ohms/square at 1V/cm. There is no stock of this type at Dupont USA. Sheet #2: 2.8 x 10E6 Ohms/square at 1V/cm. There is about 100 sq. meters of this film type at Dupont USA. Preparation: Again, 2cm wide strips were accurately sheared from the long edge of the 8 1/2" x 11" sheets supplied. These were mounted on clean paper surfaces. Copper tape contacts (effective area 2cm x 1.2cm) were applied to the foil ends so that 24 cm length of foil strip was exposed between each contact. The copper tape was the conductive through adhesive 3M type 1181. Thus the strips were 12 squares in length. Short (~1"), flexible stranded 24AWG wire was soldered to each copper contact so as not to stress the copper tape contact when electrical connections were made. The area of the contact over the foil was 'burnished' or rubbed with a rounded metal point to improve contact. This method of sample preparation is the same as that used in Part 2 of this series of reports. Measurements: Voltage and current was measured by the technique described in the Part 2 report. Results are tabled below: Sheet #1, nominal resistance 3 x 10E5 Ohms/square @1V/cm. Applied Voltage Meas. Calc. Calc. . Voltage Gradient Current Resist. Resist. (mV or V) (mV/cm) (nA) MegOhms/cm MegOhms/sq. (HP PS) 23.51mV 1 9 0.111 0.222 47.90 2 19 0.105 0.210 119.8 5 49 0.102 0.204 240.0 10 99 0.101 0.202 480.1 20 198 0.101 0.202 1.20V 50 497 0.101 0.202 2.401 100 994 0.101 0.202 4.800 200 1988 0.101 0.202 12.00 500 4975 0.101 0.202 24.00 1000 9949 0.101 0.202 (HR PS) 48.00 2000 19890 0.101 0.202 120.0 5000 49800 0.100 0.200 240.0 10000 99910 0.100 0.200 480.0 20000 201300 0.099 0.198 1200 50000 516000 0.097 0.194 2400 100000 1068600 0.094 0.188 ------------------------------------------------------------ Sheet #2, nominal resistance 2.8 x 10E6 Ohms/square @1v/cm. Applied Voltage Meas. Calc. Calc. Voltage Gradient Current Resist. Resist. (mV or V) (mV/cm) (nA) (MegOhm/cm) (MegOhm/sq.) (HP PS) -- - -- --- --- 47.75mV 2 2. 1.0 2.0 120.3 5 6. .833 1.66 240.9 10 12 .833 1.66 480.0 20 25 .800 1.60 1.199V 50 63 .794 1.59 2.400 100 128 .781 1.56 4.801 200 256 .781 1.56 11.999 500 643 .778 1.56 24.00 1000 1289 .776 1.55 (HR PS) 48.10 2000 2596 .770 1.54 120.0 5000 6576 .760 1.52 240.0 10000 13470 .742 1.48 479.9 20000 28140 .710 1.42 1200. 50000 77910 .642 1.28 2400. 100000 177000 .565 1.13 ------------------------------------------------------------ Conclusions: Both sample strips measure about 50% lower in resistance per square at the same voltage gradient of 1V/cm from the nominal value quoted by Dupont. The type of film in stock at Dupont measures about 1.66 MOhm per square for low gradients (a few mV/cm) encountered in the experimental situation. If this resistance is thought satisfactory, I will ask James Ochsner for more (we have only a single 7.7" x 11" sheet left). If the lower resistance film is desired, a search will be made to see if any Dupont distributor has the lower resistive film in stock. Low gradient measurements will be made with the new four-point probe of the same films for comparison of the two techniques. Ernie.