1、Designation: F 1663 95 (Reapproved 2002)Standard Test Method forDetermining the Capacitance of a Membrane Switch1This standard is issued under the fixed designation F 1663; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of capaci-tance(s) of a membrane switch.2. Terminology2.1 Definitions:2.1
3、1 membrane switcha momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.2.1.2 test pointstwo preselected mutually insulated loca-tions on switch assembly.3. Significance and Use3.1 Capacitance testing is useful for design verification,quality control of mat
4、erials, and workmanship.3.2 High capacitance may interfere with the reliable perfor-mance of interface electronics.3.3 Specific areas of testing are, but not limited to:3.3.1 Conductor/dielectric/conductor crossing point,3.3.2 Close proximity of conductors, and3.3.3 Any other conductive surface such
5、 as shielding ormetal backing panel.4. Interferences4.1 The following parameters may affect the results of thistest:4.1.1 Humidity,4.1.2 Contamination,4.1.3 Barometric pressure, and4.1.4 Temperature.5. Apparatus5.1 Electronic Test Instrument, for measuring very smallcapacitance (pico-farad range).6.
6、 Procedure6.1 Pretest Setup:6.1.1 Suspend the switch specimen in air or otherwiseisolate it from any interfering affects.6.1.2 Attach to the capacitance measuring instrument anynecessary leads, probes or connectors required to connect themembrane switch assembly for measurement. Place test leadsas c
7、lose to test points as possible without physical connection.(This will reduce any variations due to lead positioning).6.1.3 Record the capacitance reading indicated on the in-strument to equal capacitance (Ci) (this is the capacitance ofthe test setup).6.2 In-Process Test:6.2.1 Connect test leads to
8、 the test points.6.2.2 Record the capacitance reading indicated on the in-strument to equal total capacitance (Ct) (this is the totalcapacitance of the switch and device.7. Calculation7.1 Calculate the capacitance of the switch specimen asfollows:Capacitance Cs! 5 Ct2 Ci8. Report8.1 Report the follo
9、wing information:8.1.1 Temperature,8.1.2 Humidity,8.1.3 Barometric pressure,8.1.4 Date of test,8.1.5 Part number or description of the switch specimen, orboth,8.1.6 Conductive path(s) tested and the connection pointsused.8.1.7 Capacitance, (Ci),8.1.8 Total capacitance, (Ct),8.1.9 Capacitance of the
10、switch specimen, (Cs),8.1.10 Detailed description of isolation setup used, (includ-ing lead length, connection type, and sensitivity range), and8.1.11 Detailed description of test equipment.9. Precision and Bias9.1 The precision and bias of this test method are underinvestigation.10. Keywords10.1 ca
11、pacitance; membrane switch1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved Nov. 10, 1995. Published January 1996.1Copyright ASTM International, 100 Barr Harbor Drive, P
12、O Box C700, West Conshohocken, PA 19428-2959, United States.ASTM 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 validity of any such pa
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14、ther 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 comments have not received a fair
15、 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 multiple 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).F 16632
