ASTM_F_2749_-_15.pdf

Designation:F274915Standard Test Method forDetermining the Effects of Creasing a Membrane Switch orPrinted Electronic Device1This standard is issued under the fixed designation F2749;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 establishes a method for the creasing ofany part of a membrane switch or printed electronic devicewith conductive circuits.1.1.1 The values given in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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.Terminology2.1 Definitions:2.1.1 creasea ridge or groove made by folding and press-ing.2.1.1.1 DiscussionThe fold mark in the substrate will becaused by a roller rolled over a fold that will likely remain inthe substrate after testing.2.1.2 crease cyclea 180 degree crease followed by astraightening of the crease(see Fig.1).2.1.3 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.2.1.4 membrane switch taila flexible portion of a mem-brane switch used for input/output connection.3.Significance and Use3.1 Creasing of membrane switches,printed electronicdevice,or their components can affect their visual appearance,mechanical integrity or electrical functionality.This practicesimulates conditions that may be seen during manufacture,installation or use.3.2 Crease testing may be destructive,therefore anysamples tested should be considered unfit for future use.3.3 Specific areas of testing include,but are not limited to:3.3.1 Membrane switch flex tails or printed electronicdevice,and3.3.2 Any component of a membrane switch or printedelectronic device that may be subjected to creasing.4.Interferences4.1 The following parameters may affect the results of thistest:4.1.1 temperature,4.1.2 humidity,and4.1.3 orientation of the conductor(either extension or com-pression)could have significant impact on the results.4.1.4 Inelasticity and parallelism of roller and test bed willaffect the displacement of the force across the sample.In otherwords,the roller and test bed must not be compressible orsubject to warping or distortion during the test cycle.Furthermore,the roller must remain parallel to the test bedthrough the entire test cycle.NOTE1Experience has shown that some conductors recover theirconductive properties if allowed to stabilize after the dynamic portion ofthe test.Therefore,continuous monitoring is necessary.5.Apparatus5.1 Roller,allowed to rotate smoothly around its longitudi-nal axis,rigid,low friction smooth surface.5.1.1 Roller,measuring 50.8 mm(2 in.)in diameter,toler-ance 65%.5.2 Fixture to hold test sample securely in place in ahorizontal manner(refer to Fig.1).5.3 Mechanisms capable of providing a constant force andrate of travel to roller.5.4 Equipment for the continuous monitoring and recordingof resistance.NOTE2Experience has shown that some conductors recover theirconductive properties if allowed to stabilize after the dynamic portion ofthe test.Therefore,continuous monitoring is necessary.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 July 2015.Originally approvedin 2008.Last previous edition approved in 2009 as F 2749-09.DOI:10.1520/F2749-15.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Test Samples6.1 The test samples may be components,tail assembles orfinished switches.If the sample length is too short for the testfixture,a sample coupon of the same construction(layer tolayer)must be provided(minimum;250 mm length by 25 mmwidth).6.2 The width of the test sample must not exceed the lengthof the roller.7.Procedure7.1 Refer to Fig.1 drawing of mechanical hook up.7.1.1 Clamp one end of the test sample to the test fixture this is the static end of the test sample.7.1.1.1 Compression Conductor Testingconductor side ofthe test sample faces away from the roller.7.1.1.2 Extension Conductor Testingconductor side of thetest sample faces the roller.NOTE3If direction not specified perform both compression andextension conductor testing.7.1.2 Loop the unsecured end(dynamic end)of the testsample underneath the static portion.7.1.3 Clamp the dynamic end of the test sample to thedynamic position of the test fixture.7.1.3.1 Ensure that the both ends of the test sample remainaligned(one on top of another)during motion of