1、Designation: F1896 10Test 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 of last
2、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 elec-trical resistivity of a conductive material as used in themanufacture
3、 of a membrane switch.1.2 This test method is not suitable for measuring forcesensitive conductive materials.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are
4、not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prio
5、r to use.2. Terminology2.1 Definitions:2.1.1 membrane switcha momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.2.1.2 circuit/test pattern resistanceelectrical resistance asmeasured between two terminations of a circuit trace.2.1.3 squareA geometric unit
6、of a printed conductivecircuit trace/pattern obtained by dividing the length (L)oftheprinted conductive circuit trace/pattern by its width (W).2.1.4 resistivityohms per square per mil of a conductivematerial.3. Significance and Use3.1 Resistivity is useful to suppliers and manufacturers asfollows:3.
7、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 qualitycontrol.4. Interferences4.1 The precision and bias of this test method are
8、 underinvestigation. The accuracy of the resistivity determination willbe improved as the number of squares of the resistance teststrip is increased. The accuracy of the resistivity determinationwill be improved as the width (W) of the circuitry test patternis increased. Some conductive materials re
9、sistivity are sensi-tive to temperature and the temperature of the test specimenshould be noted and recorded.5. Apparatus5.1 Resistance Measuring Device, (that is, ohm meter)equipped with test leads and probes. The device should becapable of measuring resistances up to 100 MV with anaccuracy of grea
10、ter than 1.5 % of full scale reading. Test probesshould have tips that are 25 to 250 % of the width (W)oftheprinted conductor test pattern.5.2 Test Surface, to be flat, smooth, unyielding and largerthan switch under test.5.3 Thickness Measuring Device, capable of measuring tothe nearest 0.00005 in.
11、(1.25 m).5.4 Dimensional Measuring Device, capable of measuringto the nearest 0.001 in. (25 m).6. Test Specimen6.1 A resistance test strip of printed and cured conductivematerial with a minimum length (L) to width (W) ratio of 50:1(equal to or greater than 50 squares). A pattern of membraneswitch ci
12、rcuitry is sufficient if a straight measurable strip, witha minimum length (L) to width (W) ratio of 50:1 (equal to orgreater than 50 squares), is available. The accuracy of theresistivity determination will be improved as the number ofsquares of the resistance test strip is increased.7. Procedure7.
13、1 Pre-Test Setup:7.1.1 Secure switch/test pattern (that is, printed and curedconductive material) on the test surface.7.1.2 Measure the geometry of the test pattern as follows:1This test method is under the jurisdiction of Committee F01 on Electronics ,and is the direct responsibility of Subcommitte
14、e F01.18 on Membrane Switches.Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1998. Last previous edition approved in 2004 as F1896 - 98 (2004).DOI: 10.1520/F1896-10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
15、United States.7.1.2.1 Measure the length (L) of the printed test pattern.7.1.2.2 Measure the width (W) of the printed test pattern.7.1.2.3 Divide the length (L) by the width (W) to calculatethe number of squares of the printed test pattern. Should be$50 squares.NOTE 1Measuring the length (L) and wid
16、th (W) of the actual printedpattern checks the accuracy of the actual number of squares printed versusthe artwork.7.2 In-Process Test:7.2.1 Using the resistance measuring device (that is, ohmmeter), measure the resistance of the printed test pattern. Placeprobes at ends of measured length of the tes
17、t pattern as shownin Fig. 1.7.2.2 Record resistance in ohms.7.2.3 Using the thickness measuring device, measure thethickness (t) of the printed test pattern in mils, measure in aminimum of three locations across the test pattern.7.2.4 Record average thickness (t) in mils (1 mil = 25 m).7.3 Calculati
18、ons:7.3.1 Determine the number of squares of the printed testpattern by dividing the length (L) by the width (W). Record thenumber of squares.7.3.2 Determine the ohms per square by dividing the mea-sured resistance (in ohms) by the number of squares. Recordthe ohms per square.7.3.3 Determine the res
19、istivity (ohms per square per mil) ofthe conductive material by multiplying the ohms per square bythe measured thickness (t) in mils. Record the resistivity of theconductive material (ohms per square per mil).7.3.4 Examples:7.3.4.1 Example No. 1 is as follows:Resistance Measurement: 3.0 VThickness (
20、t) Measurement: 0.50 mils (12.5 m)Number of Squares: 100 squaresOhms per square = 3.0 V/100 squaresOhms per square = 0.03 V per squareResistivity (ohms per square per mil) = 0.03 V per square 3 0.50 milsResistivity (ohms per square per mil) = 0.0157.3.4.2 Example No. 2 is as follows:Resistance Measu
21、rement: 3.0 VThickness (t) Measurement: 12.5 mNumber of Squares: 100 squaresOhms per square = 3.0 V/100 squaresOhms per square = 0.03 V per squareResistivity (ohms per square per inch) = 0.03 V per square 3 0.0005in.Resistivity (ohms per square per inch) = 0.000015Resistivity (ohms per square per mi
22、l) = 0.000015 3 1000 mils per inchResistivity (ohms per square per mil) = 0.0158. Report8.1 Report the following information:8.1.1 Temperature,8.1.2 Humidity,8.1.3 Resistance (ohms),8.1.4 Number of squares,8.1.5 Thickness (t) of the test pattern,8.1.6 Resistivity (ohms per square per mil),8.1.7 Part
23、 number or description, or both, of the testpattern/switch,8.1.8 Identify termination points, and8.1.9 Date of test.9. Precision and Bias9.1 PrecisionIt is not possible to specify the precision ofthe procedure in Test Method F1896 for measuring the resis-tivity because inter-laboratory studies have
24、proven inconclu-sive due to insufficient participating laboratories with theappropriate equipment.9.2 BiasNo information can be presented on the bias ofthe procedure in Test Method F1896 for measuring resistivitybecause no standard sample is available for this industry.10. Keywords10.1 conductive ma
25、terial; membrane switch; resistivityFIG. 1 Resistance Measurement Test Set-UpF1896 102ASTM 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 t
26、he validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Yo
27、ur comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comment
28、s have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or mul
29、tiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).F1896 103
