1、Designation: F 2749 09Standard Test Method forDetermining the Effects of Creasing a Membrane Switch orAssembly1This standard is issued under the fixed designation F 2749; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 with conductive circuits.1.1.1
3、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-pr
4、iate 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 andpressing.2.1.1.1 DiscussionThe fold mark in the substrate will becaused by a roller rolled over a fold that will lik
5、ely 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
6、 mem-brane switch used for input/output connection.3. Significance and Use3.1 Creasing of membrane switches or their components canaffect their visual appearance, mechanical integrity or electricalfunctionality. This practice simulates conditions that may beseen during manufacture, installation or u
7、se.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, and3.3.2 Any component of a membrane switch that may besubjected to creasing.4. Interference
8、s4.1 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 displaceme
9、nt 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. Further-more, the roller must remain parallel to the test bed through theentire test cycle.NOTE 1Experience has shown that some conductors reco
10、ver 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 d
11、iameter, 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.NOTE 2Experience has shown that so
12、me conductors recover theirconductive properties if allowed to stabilize after the dynamic portion ofthe test. Therefore, continuous monitoring is necessary.6. Test Samples6.1 The test samples may be components, tail assembles orfinished switches. If the sample length is too short for the testfixtur
13、e, 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.1This test method is under the jurisdiction of AS
14、TM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwetches.Current edition approved June 15, 2009. Published November 2009. Originallyapproved in 2008. Last previous edition approved in 2008 as F 2749-08.1Copyright ASTM International, 100 Barr Harbor D
15、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 Testing
16、conductor side of thetest sample faces the roller.NOTE 3If 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
17、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 test.7.1.4 Connect to the test sample so that circuit resistancecan be monitored continuously.NOTE 4Experience has shown that some conductors recover theirconductive proper
18、ties if allowed to stabilize after the dynamic portion ofthe test. Therefore, continuous monitoring is necessary.7.1.4.1 Verify test sample is functional and being moni-tored.7.1.4.2 Record the closed loop resistance (Ri) - measure-ment made before the first test cycle.7.1.4.3 Apply constant force o
19、f predetermined value verti-cally to roller (see Fig. 1).7.1.4.4 Start test.7.1.5 Roll the roller from the clamped ends of the specimentoward the end of the loop (Fig. 1). Speed shall be approxi-mately 25 mm/s. Roll the roller completely off of the loopcreating a crease.7.1.6 Immediately open the cr
20、eased specimen such that thecrease is now open.7.1.7 Straighten the test sample. (DO NOT ROLL ROLLEROVER THE OPENED CREASE.)FIG. 1 Test Fixture SetupF27490927.1.7.1 A cycle is defined as; moving from a creasedposition to a straightened position and returning to a creasedposition.7.1.8 Repeat for 500
21、 cycles. Dwell time between cyclesshould be limited to the compression cycle time 62s.Ifanaverage (per cycle) increase in resistance (30 % or greater ofRi) is achieved in ten (10) consecutive cycles, before the 500cycle limit, stop the test and record cycles.7.1.9 Remove test sample from test fixtur
22、e.8. Report8.1 Report the following information:8.1.1 Temperature,8.1.2 Humidity,8.1.3 Number of cycles per test sample,8.1.4 Resistance measurements, Ri, R maximum, R aver-age,8.1.5 Part number or description of test sample,8.1.6 Date of test,8.1.7 Orientation of test sample (compression, extension
23、, orboth),8.1.8 Diameter of roller, and8.1.9 Weight/Force of roller.9. Precision and Bias9.1 PrecisionIt is not possible to specify the precision ofthe procedure in Test Method F 2749 for measuring creasebecause inter-laboratory studies have proven inconclusive dueto insufficient participating labor
24、atories with the appropriateequipment.9.2 BiasNo information can be presented on the bias ofthe procedure in Test Method F 2749 for measuring creasebecause no standard sample is available for this industry.10. Keywords10.1 bend; crease; mandrel; membrane switch; tail assemblyASTM International takes
25、 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 resp
26、onsibility.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 addresse
27、d 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 hearing you shouldmake your views known to the ASTM Committee on Standards, at the
28、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).F2749093
