1、Designation: F2750 09F2750 16Standard Test Method forDetermining the Effects of Bending a Membrane Switch orAssemblyPrinted Electronic Device1This standard is issued under the fixed designation F2750; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 bending of any part of a membrane switch o
3、r printed electronic device withconductive circuits.1.1.1 The values given in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the res
4、ponsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Terminology2.1 Definitions:2.1.1 bendto force from a straight form into a different and especially a curved one.2.1.1.1 DiscussionIn t
5、his case, no “hard” or angled crease or fold is to occur. The substrate will only be formed into a radius.2.1.2 bend cyclea bend of a sample around a specified mandrel which is “rolled” in one direction, followed by rolling in theopposite direction, returning the sample to its original position (see
6、 Fig. 1).2.1.3 mandrela cylindrically shaped metal rod, such as a brazing or drill rod.2.1.4 membrane switcha momentary switching device in which at least one contact is on, or made of, a flexible substrate.2.1.5 membrane switch taila flexible portion of a membrane switch used for input/output conne
7、ction.3. Significance and Use3.1 Bending of membrane switches switches, printed electronic device or their components can affect their visual appearance,mechanical integrity or electrical functionality. This test method simulates conditions that may be seen during manufacture,installation or use.3.2
8、 Bend testing may be destructive, therefore any samples 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, tails or printed electronic device, and3.3.2 Any component of a membrane switch or printed electron
9、ic device that may be subjected to bending.4. Interferences4.1 The following parameters may affect the results of this test:4.1.1 temperature,4.1.2 humidity, and4.1.3 orientation of the conductor (either extension or compression) could have significant impact on the results.NOTE 1Experience has show
10、n that some conductors recover their conductive properties if allowed to stabilize after the dynamic portion of the test.Therefore, continuous monitoring is recommended.1 This test method is under the jurisdiction ofASTM Committee F01 on Electronics and is the direct responsibility of Subcommittee F
11、01.18 on Membrane SwitchesPrintedElectronics.Current edition approved June 15, 2009May 1, 2016. Published July 2009May 2016. Originally approved in 2008. Last previous edition approved in 20082009 asF2750-08.-09. DOI: 10.1520/F2750-09.10.1520/F2750-16.This document is not an ASTM standard and is int
12、ended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the curr
13、ent versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Apparatus5.1 Mandrel, allowed to rotate smoothly around its longitudinal axis, rigid, low fri
14、ction smooth surface. Diameter to bespecified.5.2 Fixture to hold test sample securely in place in a vertical manner (refer to Fig. 1).5.3 Mechanism capable of providing a consistent force and rate of pull to the sample.5.4 Equipment for the monitoring and recording of resistance.NOTE 2Experience ha
15、s shown that some conductors recover their conductive properties if allowed to stabilize after the dynamic portion of the test.Therefore, continuous monitoring is recommended.6. Test Samples6.1 The test samples may be components, tail assembles or finished switches. If the sample length is too short
16、 for the test fixture,a sample coupon of the same construction (layer to layer) must be provided (minimum; 250 mm length by 25 mm width).6.2 The width of the test sample must not exceed the length of the mandrel.7. Procedure7.1 Clamp one end of the test sample to the test fixture this is the static
17、end of the test sample.7.1.1 Compression Conductor Testing conductor side of the test sample faces the mandrel.7.1.2 Extension Conductor Testing conductor side of the test sample faces away from the mandrel.7.2 Loop the unsecured end of the test sample around the mandrel this later becomes the dynam
18、ic end of the test sample.7.3 Clamp the unsecured end of the test sample to the lifting mechanism (no tension).7.3.1 Ensure that both ends of the test sample remain parallel during motion of test.7.4 Connect to the test sample so that circuit resistance can be monitored.NOTE 3Experience has shown th
19、at some conductors recover their conductive properties if allowed to stabilize after the dynamic portion of the test.Therefore continuous monitoring is recommended.7.4.1 Verify test sample is functional and being monitored.FIG. 1 Test Fixture SetupF2750 1627.5 Apply the minimum tension load of suffi
20、cient magnitude such that the test sample contacts 50 % of the circumferencesurface of the mandrel. (Typically, this is a kg mass providing the tension load.)7.6 Adjust the test fixture to achieve maximum travel of the mandrel by pulling the unsecured end (dynamic end) of the testsample while mainta
21、ining 50 % contact with the mandrel.7.7 Start test.7.7.1 Record the closed loop resistance (Ri) - measurement made on the first test cycle.At the end of the test, the “R maximum”value, which is the largest value using a time constant chosen appropriately for the measurement, is recorded.7.7.2 A cycl
22、e is defined as travel from maximum extension to minimum extension and back to maximum extension.7.7.3 The linear speed of the dynamic end of the test sample should not exceed 25.4 mm/s.7.8 Repeat cycles until resistance increases by 30 % or more of Ri for 10 consecutive cycles or the specified numb
23、er of cyclesare completed. Resistance is to be continuously monitored or measured within 3 s of cycling. Time between cycles shall not exceed3 s.7.9 Remove test sample from test fixture.8. Report8.1 Report the following information:8.1.1 Temperature,8.1.2 Humidity,8.1.3 Resistance measurements, Ri,
24、R maximum,8.1.4 Number of cycles per specimen,8.1.5 Part number or description of specimen,8.1.6 Date of test,8.1.7 Orientation of test sample (compression, extension, or both),8.1.8 Diameter of mandrel, and8.1.9 Load weight.9. Precision and Bias9.1 PrecisionIt is not possible to specify the precisi
25、on in Test Method F2750 for measuring bend because inter-laboratorystudies have proven inconclusive due to insufficient participating laboratories with the appropriate equipment.9.2 BiasNo information can be presented on the bias of the procedure in Test Method F2750 for measuring bend because nosta
26、ndard sample is available for this industry.10. Keywords10.1 bend; mandrel; membrane switch; printed electronic device; 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 standar
27、d are expressly 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
28、not revised, 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
29、 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 address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,Uni
30、ted 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 163
