ASTM F2749-2008 Standard Test Method for Determining the Effects of Creasing a Membrane Switch or Assembly.pdf

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1、Designation: F 2749 08Standard 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 weight rolled over a fold that will lik

5、ely remain inthe substrate after testing.2.1.2 crease cyclea 180 degree crease followed by aflattening 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 me

6、m-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 use.

7、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 bending.4. Interferences4.1

8、 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.5. Apparatus5.1 Cylinder, allowed to rotate smoothly around its longi-tudinal axis, rig

9、id, low friction smooth surface.5.1.1 Cylinder 2” Specification, 1 kg in size, measuring 50.8mm (2 in.) in diameter by 68.6 mm (2.7 in.) in height. Weightand dimensions of weight to be within 65%.5.1.2 Cylinder 1” Specification, 2 kg in size, measuring 63.5mm (2.5 in.) in diametr by 86.4 mm (3.4 in.

10、) in height. Weightand dimensions of weight to be within 65%.5.1.3 Other SpecificationsDimensions or weight/force tobe specified.5.2 Fixture to hold test sample securely in place in ahorizontal manner (refer to Fig. 1).5.3 Mechanisms capable of providing a consistent force andrate of travel to the t

11、est sample.5.4 Equipment for the continuous monitoring and recordingof resistance.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 provide

12、d (minimum; 250 mm length by 25 mmwidth).6.2 The width of the test sample must not exceed the lengthof the cylinder.7. Procedure7.1 Refer to Fig. 1 drawing of electrical/mechanical hookup.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility

13、 of Subcommittee F01.18 on MembraneSwitches.Current edition approved Nov. 1, 2008. Published December 2008.1Copyright ASTM International, 100 Barr Harbor Drive, 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

14、end of the test sample.7.1.1.1 Compression Conductor Testingconductor side ofthe test sample faces away from the cylinder.7.1.1.2 Extension Conductor Testingconductor side of thetest sample faces the cylinder.NOTE 1If direction not specified perform both compression andextension conductor testing.7.

15、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 test.7.1.4 Co

16、nnect to the test sample so that circuit resistancecan be monitored continuously.NOTE 2Experience has shown that some conductors recover theirconductive properties if allowed to stabilize after the dynamic portion ofthe test. Therefore, continuous monitoring is necessary.7.1.4.1 Verify test sample i

17、s 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 Start test.7.1.5 Roll the weight from the clamped ends of the speci-men toward the end of the loop (Fig. 1). Speed shall beapproximately 25 mm/s. Roll the weight c

18、ompletely off of theloop creating a crease.7.1.6 Immediately open the creased specimen such that thecrease is now open.7.1.7 Straighten the test sample. (DO NOT ROLL CYLIN-DER OVER THE OPENED CREASE.)7.1.7.1 A cycle is defined as crease position to straightenposition.7.1.8 Repeat for 500 cycles. Dwe

19、ll time between cyclesshould not exceed 1 s. If an average (per cycle) increase inresistance (30 % or greater of Ri) is achieved in ten (10)consecutive cycles, before the 500 cycle limit, stop the test andrecord cycles.7.1.9 Remove test sample from test fixture.8. Report8.1 Report the following info

20、rmation: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, orboth),8.1.8 Diameter of cylinder, an

21、dFIG. 1 Test Fixture SetupF27490828.1.9 Load Weight/Force.9. Keywords9.1 bend; crease; mandrel; membrane switch; tail assemblyASTM 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 e

22、xpressly 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 rev

23、ised, 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 m

24、ay 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 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).F2749083