ASTM_F_1680_-_07a_2014.pdf

Designation:F168007a(Reapproved 2014)Standard Test Method forDetermining Circuit Resistance of a Membrane Switch1This standard is issued under the fixed designation F1680;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year 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 circuitresistance of a membrane switch.1.2 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 prior to use.2.Referenced Documents2.1 ASTM Standards:2F2592 Test Method for Measuring the Force-Displacementof a Membrane Switch3.Terminology3.1 Definitions:3.1.1 circuit resistanceelectrical resistance as measuredbetween two test points whose internal contacts,when heldclosed,complete a circuit.3.1.2 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.4.Significance and Use4.1 Resistance is useful to manufacturers and users whendesigning membrane switch interface circuitry.5.Apparatus5.1 Test Probe,as defined in Test Method F2592.5.2 Test Surface to be flat,smooth,unyielding and largerthan switch under test.5.3 Device,to hold test probe securely and provide perpen-dicular movement into and away from switch under test.5.4 Resistance Measuring Device,(for example,ohmmeter).The device should not apply a voltage outside theoperating range of the switch contacts.5.5 Suitable Device,to apply a controlled and measurableforce on the test probe.6.Procedure6.1 Pre-Test Setup:6.1.1 Precondition switch until approximation of steadystate condition is achieved.(Note this will typically occurbetween 5 to 25 cycles,and it is recommended that theinstrument and test probe be used when practical.)6.1.2 Secure switch on test surface so that the unit under testcan be removed and replaced in the same position aftersubsequent operations(probe contact position within 0.010 in.of its original position on the switch).6.1.3 Position test probe over desired are of switch.6.1.4 Lower probe until tip is just above top surface ofswitch without touching.6.1.5 Connect switch terminals to resistance measuringdevice.6.2 In-Process Test:6.2.1 Slowly depress switch with probe until the resistancedoes not change for very small increments of force(forexample 28 g).6.2.2 Slowly retract probe until the resistance shows mini-mal change.6.2.3 Record force and resistance retract probe to 6.1.4.6.2.4 Depress switch with probe at the force recorded in6.2.3 four additional times.Record resistance.6.2.4.1 If resistance levels are not within 5%of each otherrepeat 6.2.1 through 6.2.3 using a different force.The force willneed to be adjusted to achieve the five sequential resistancemeasurements.7.Report7.1 Report the following information:7.1.1 Barometric pressure,7.1.2 Test probe,7.1.3 Force,7.1.4 Average Resistance,7.1.5 Description of probe holding fixture and monitoringdevice,1This 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 June 1,2014.Published July 2014.Originally approvedin 1996.Last previous edition approved in 2007 as F1680-07a.DOI:10.1520/F1680-07AR14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.1.6 Part number or description of switch,or both,7.1.7 Identify termination points,and7.1.8 Date of test.8.Precision and Bias8.1 The precision and bias of this test method are underinvestigation.8.2 Repeated testing will improve precision.9.Keywords9.1 membrane switch;resistanceASTM 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 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.Your 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