ASTM_F_1661_-_09_2015.pdf

Designation:F166109(Reapproved 2015)Standard Test Method forDetermining the Contact Bounce Time of a MembraneSwitch1This standard is issued under the fixed designation F1661;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 contactbounce time of a membrane switch.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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:2D2240 Test Method for Rubber PropertyDurometer Hard-nessF2592 Test Method for Measuring the Force-Displacementof a Membrane SwitchF1680 Test Method for Determining Circuit Resistance of aMembrane Switch3.Terminology3.1 Definitions:3.1.1 contact bounceintermittent contact opening andcontact closure that may occur after switch operation.3.1.2 contact bounce time(break),TCBBthe time periodmeasured from the first instant VMis equal to the SUTV untilit constantly remains below the SLTV after the last instant itrises above the SUTV.If VMdoes not rise above SUTV duringthe time interval,TCBB=0,(see Fig.1).3.1.3 contact bounce time(make),TCBMthe time periodmeasured from the first instant VMis equal to the SLTV untilit constantly remains above the SUTV after the last instant itfalls below the SLTV.If VMdoes not fall below SLTV duringthe time interval,TCBM=0,(see Fig.2).3.1.4 lower transition voltage,LTVthe voltage at whichthe switched logic device transitions to an“off”state.3.1.5 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.3.1.6 resistor,load,RLload resistance in series with switchunder test.3.1.7 specified lower transition voltage,SLTV minimumallowable LTV.3.1.8 specified upper transition voltage,SUTV minimumallowable UTV.3.1.9 upper transition voltage,UTVthe voltage at whichthe switched logic device transitions to an on”state.3.1.10 voltage,measured,VMvoltage measured acrossload Resistor(RL)by the oscilloscope and measured on itsscreen or voltage measured across the switch under test whena contact bounce measuring device is used.4.Significance and Use4.1 Contact bounce time is essential to manufacturers andusers when designing interface circuitry because it specifies thetime delay necessary in the decoder circuitry to avoid any falsesignals caused by contact bounce.Allowing for time delaymakes the switch operation considerably more reliable.5.Interference5.1 The following parameters may affect the results of thistest:5.1.1 Mechanical probe materials(hardness)and speed willaffect results.6.Apparatus6.1 Test Probe,built to either of the configuration shown inFig.3 and Fig.4 are acceptable but must be made of an inertelastomeric material with a hardness number equivalent toA/45 6 5 as measured in accordance with Test Method D2240.Test probes that do not meet the above criteria must be fullyspecified and recorded.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on PrintedElectronics.Current edition approved June 1,2015.Published August 2015.Originallyapproved in 1995.Last previous edition approved in 2009 as F1661 09.DOI:10.1520/F1661-09R15.2For 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 6.2 Test Surface flat,smooth,unyielding,and larger thanswitch under test.6.3 Oscilloscope,with recording capabilities and powersupply,or suitable contact bounce time measuring instrument.6.4 Device,which will consistently move probe into andaway from the switch at a controlled speed.Also capable ofapplying a specified force.7.Procedure7.1 Pretest Setup:7.1.1 Determine Fmax or Fc(whichever is greater)per TestMethod F2592.7.1.2 Determine switch resistance(RS)per Test MethodF1680.7.1.3 Secure switch on test surface.7.1.4 Connect switch terminals as shown in Fig.5 so that:RL5 10 to 100 times RS7.1.5 Adjust oscilloscope to initial settings as follows:7.1.5.1 One half to 1.0 V/cm vertical,and7.1.5.2 Two to 3 ms/cm horizontal.7.1.5.3 Set SUTV per Fig.6 if known.If not known,defaultSUTV will be 2.0 VDC.7.1.5.4 Set SLTV per Fig.6 if known.If not known,defaultSLTV will be 0.9 VDC.7.1.6 Adjust power supply to t