ASTM_F_1762_-_14.pdf

Designation:F176214Standard Test Method forDetermining the Effects of Atmospheric Pressure Variationon a Membrane Switch1This standard is issued under the fixed designation F1762;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 a procedure for exposing amembrane switch to variations in atmospheric pressure.It canbe used to determine the effects of pressure variations onchemical and mechanical properties and functional character-istics of the switch.2.Referenced Documents2.1 ASTM Standards:2F1595 Practice for Viewing Conditions for Visual Inspectionof Membrane SwitchesF1663 Test Method for Determining the Capacitance of aMembrane SwitchF1680 Test Method for Determining Circuit Resistance of aMembrane SwitchF1689 Test Method for Determining the Insulation Resis-tance of a Membrane SwitchF1895 Test Method for Submersion of a Membrane SwitchF2592 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 contact closurethe event at which a specified resis-tance is achieved on a membrane switch.3.1.3 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.3.1.4 specified resistancethe maximum allowable circuitresistance as measured between two test points whose internalcontacts,when held closed,complete a circuit.3.1.5 test pointstwo preselected conductive points in acircuit loop,possibly including a switch.4.Significance and Use4.1 Erratic operation or malfunction of a membrane switchresulting from changes in the specified switch characteristics,4.2 Rupture,implosion or explosion of seals due to pressurevariations,4.3 Change in physical or chemical properties due to pres-sure differentiations,and4.4 Delaminations of a membrane switch may occur due topressure variations.5.Interferences5.1 Time duration before,during and after pressure cycling,5.2 Temperature,5.3 Humidity,5.4 Mounting Method(if applicable).6.Apparatus6.1 Pressure Chamber,a chamber or cabinet capable ofmaintaining a specified pressure.If procedurally required,theapparatus shall be capable of providing pressure variation at aspecified rate.6.2 Monitoring Device,suitable to detect contact closure(that is,ohm meter,etc.).7.Conditioning7.1 Condition all specimens for 72 h at ambient laboratoryconditions immediately prior to exposure,or prior to pressurecycling.This is to enable the specimens to stabilize.8.Procedure8.1 Pretest Setup: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 Jan.1,2014.Published January 2014.Originallyapproved in 1996.Last previous edition approved in 2007 as F176207.DOI:10.1520/F1762-14.2For 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 8.1.1 Measure or observe the desired characteristics of theswitch so that comparable measurements and observations canbe made prior to,during and after the test.Some suggestedvalues are:8.1.1.1 Circuit resistance in accordance with Test MethodF1680.8.1.1.2 Capacitance in accordance with Test Method F1663.8.1.1.3 Force displacement in accordance with Test MethodF2592.8.1.1.4 Insulation resistance in accordance with TestMethod F1689.8.1.1.5 Submersion in accordance with Test Method F1895(for sealed switch only).8.1.1.6 Visual inspection in accordance with Test MethodF1595.8.1.2 Connect predetermined switch terminations to resis-tance measuring device.8.2 In-Process Test:8.2.1 Place specimens in the chamber at ambient conditions,record time and date,and initiate measuring device.8.2.2 Adjust the ramp rate to decrease air pressure at 2000ft/min unless otherwise specified.8.2.3 Set pressure at desired level from Table 1.8.2.4 Maintain the chamber pressure for the one hour or aspecified time interval.8.2.5 Return chamber pressure to the initial ambient condi-tions at the specified rate.8.2.6 Remove specimens and record time and date.8.3 Post Test:8.3.1 Measure and observe the characteristics of the switchas in 8.1.1.Record time and date for each characteristicmeasured.9.Report9.1 Report the following information:9.1.1 Pressure level(from Table 1).9.1.2 Time interval.9.1.3 Ramp rate.9.1.4 Temperature.9.1.5 Humidity.9.1.6 Change in measured or observed characteristics.9.1.7 Any s