1、Designation: F1896 10F1896 16Test Method forDetermining the Electrical Resistivity of a PrintedConductive Material1This standard is issued under the fixed designation F1896; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the electrical resistivity of a conductive material as used in the man
3、ufactureof a membrane switch.1.2 This test method is not suitable for measuring force sensitive conductive materials.1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onl
4、y and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitati
5、ons prior to use.2. Terminology2.1 Definitions:2.1.1 membrane switcha momentary switching device in which at least one contact is on, or made of, a flexible substrate.2.1.2 circuit/test pattern resistanceelectrical resistance as measured between two terminations of a circuit trace.2.1.3 squareA geom
6、etric unit of a printed conductive circuit trace/pattern obtained by dividing the length (L) of the printedconductive circuit trace/pattern by its width (W).2.1.4 resistivityohms per square per mil of a conductive material.3. Significance and Use3.1 Resistivity is useful to suppliers and manufacture
7、rs as follows:3.1.1 when designing membrane switch interface circuitry,3.1.2 when selecting the appropriate conductive material,3.1.3 for conductive material quality verification, and3.1.4 for conductive material cure optimization and quality control.4. Interferences4.1 The precision and bias of thi
8、s test method are under investigation. The accuracy of the resistivity determination will beimproved as the number of squares of the resistance test strip is increased. The accuracy of the resistivity determination will beimproved as the width (W) of the circuitry test pattern is increased. Some con
9、ductive materials resistivity are sensitive totemperature and the temperature of the test specimen should be noted and recorded.temperature.5. Apparatus5.1 Resistance Measuring Device, (that is, ohm meter) equipped with test leads and probes. The device should be capable ofmeasuring resistances up t
10、o 100 M with an accuracy of greater than 1.5 % of full scale reading. Test probes should have tips thatare 25 to 250 % of the width (W) of the printed conductor test pattern. If your device is not equipped with a feature that allowsthe resistance of the leads to be negated then measure the lead resi
11、stance and subtract that from the resistance measurements.1 This test method is under the jurisdiction of Committee F01 on Electronics, and is the direct responsibility of Subcommittee F01.18 on Membrane SwitchesPrintedElectronics.Current edition approved May 1, 2010May 1, 2016. Published June 2010M
12、ay 2016. Originally approved in 1998. Last previous edition approved in 20042010 as F1896- 98 (2004). 10. DOI: 10.1520/F1896-10.10.1520/F1896-16.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the prev
13、ious version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM In
14、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Test Surface, to be flat, smooth, unyielding and larger than switchcircuit under test.5.3 Thickness Measuring Device, capable of measuring to the nearest 0.00005 in. (1.25 m).5.4 Dimensional Measurin
15、g Device, capable of measuring to the nearest 0.001 in. (25 m).6. Test Specimen6.1 Aresistance test strip of printed and cured conductive material with a minimum length (L) to width (W) ratio of 50:1 (equalto or greater than 50 squares). A pattern of membrane switch circuitry is sufficient if a stra
16、ight measurable strip, with a minimumlength (L) to width (W) ratio of 50:1 (equal to or greater than 50 squares), is available. The accuracy of the resistivity determinationwill be improved as the number of squares of the resistance test strip is increased.6. Procedure6.1 Pre-Test Setup:6.1.1 Secure
17、 switch/test pattern circuit (that is, printed and cured conductive material) on the test surface.6.1.2 Measure the geometry of the test pattern as follows:6.1.2.1 Measure the length (L) of the printed test pattern. (L) is the length of the conductive path between test probes.NOTE 1It is possible th
18、at (L) is smaller than (W).6.1.2.2 Measure the width (W) of the printed test pattern.6.1.2.3 Divide the length (L) by the width (W) to calculate the number of squares of the printed test pattern. Should be 50squares.NOTE 2Measuring the length (L) and width (W) of the actual printed pattern checks th
19、e accuracy of the actual number of squares printed versus theartwork.6.2 In-Process Test:6.2.1 Using the resistance measuring device (that is, ohm meter), measure the resistance of the printed test pattern. Place probesat ends of measured length of the test pattern as shown in Fig. 1.NOTE 3Reminder
20、to zero out test probe leads.6.2.2 Record resistance in ohms.6.2.3 Using the thickness measuring device, measure the thickness (t) of the printed test pattern in mils, measure in a minimumof three locations across the test pattern.6.2.4 Record average thickness (t) in mils (1 mil = 25 m).6.3 Calcula
21、tions:6.3.1 Determine the number of squares of the printed test pattern by dividing the length (L) by the width (W). Record the numberof squares.6.3.2 Determine the ohms per square by dividing the measured resistance (in ohms) by the number of squares. Record the ohmsper square.6.3.3 Determine the r
22、esistivity (ohms per square per mil) of the conductive material by multiplying the ohms per square by themeasured thickness (t) in mils. Record the resistivity of the conductive material (ohms per square per mil).FIG. 1 Resistance Measurement Test Set-UpF1896 1626.3.4 Examples:6.3.4.1 Example No. 1
23、is as follows:Resistance Measurement: 3.0Thickness (t) Measurement: 0.50 mils (12.5 m)Number of Squares: 100 squaresOhms per square = 3.0 /100 squaresOhms per square = 0.03 per squareResistivity (ohms per square per mil) = 0.03 per square 0.50 milsResistivity (ohms per square per mil) = 0.0156.3.4.2
24、 Example No. 2 is as follows:Resistance Measurement: 3.0Thickness (t) Measurement: 12.5 mNumber of Squares: 100 squaresOhms per square = 3.0 /100 squaresOhms per square = 0.03 per squareResistivity (ohms per square per inch) = 0.03 per square 0.0005in.Resistivity (ohms per square per inch) = 0.00001
25、5Resistivity (ohms per square per mil) = 0.000015 1000 mils per inchResistivity (ohms per square per mil) = 0.0157. Report7.1 Report the following information:7.1.1 Temperature,7.1.2 Humidity,7.1.3 Resistance (ohms),7.1.4 Number of squares,7.1.5 Thickness (t) of the test pattern,7.1.6 Resistivity (o
26、hms per square per mil),7.1.7 Part number or description, or both, of the test pattern/switch,7.1.8 Identify termination points, and7.1.9 Date of test.8. Precision and Bias8.1 PrecisionIt is not possible to specify the precision of the procedure in Test Method F1896 for measuring the resistivitybeca
27、use inter-laboratory studies have proven inconclusive due to insufficient participating laboratories with the appropriateequipment.8.2 BiasNo information can be presented on the bias of the procedure in Test Method F1896 for measuring resistivity becauseno standard sample is available for this indus
28、try.9. Keywords9.1 conductive material; membrane switch; resistivityF1896 163ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validi
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