1、Designation: F1996 06F1996 14Standard Test Method forSilver Migration for Membrane Switch Circuitry1This standard is issued under the fixed designation F1996; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 is used to determine the susceptibility of a membrane switch to the migration of the silver between circuittraces
3、 under dc voltage potential.1.2 Silver migration will occur when special conditions of moisture and electrical energy are present.2. Referenced Documents2.1 ASTM Standards:2F1596 Test Method for Exposure of Membrane Switches to Temperature and Relative HumidityF1689 Test Method for Determining the I
4、nsulation Resistance of a Membrane Switch3. Terminology3.1 Definitions:3.1.1 silver migrationA process by which silver, when in contact with insulating materials under electrical potential, isremoved ionically from its original location, and is redeposit as a metal (silver dendrite) at some other lo
5、cation.4. Significance and Use4.1 The effects of silver migration are short circuiting or reduction in insulation resistance. It is evidenced by staining ordicoloration between the cathode and anode conductive traces.4.2 Accelerated testing may be accomplished by increasing the voltage over the spec
6、ified voltages. (A typical starting pointwould be 5Vdc 50mA).5. Interferences5.1 The following parameters may affect the results of this test:5.1.1 Temperature.5.1.2 Relative Humidity.5.1.3 Electrical Load (that is, current and voltage).5.1.4 Test surface.5.1.5 Flex tail connector area may be suscep
7、tible to silver migration which may or may not be a part of the scope of this test.If the flex tail is to be excluded from the test it should be sealed with an inert compound that has no influence on the test or switchmaterials.5.1.6 Post test handling may damage or destroy silver dendrites.5.1.7 De
8、ndrites normally grow from the cathode conductor to the anode. To test both electrodes of a switch design connectreplicate specimens so that current flows through them in opposite directions.5.1.8 Without limited current, the migration could occur, causing a short and a dramatic current surge, which
9、 then destroys theshort and returns the circuit to a nonstandard, but functional condition. If an observer was not present (or the details were notcontinuously recorded) this most dramatic failure might go unnoticed.5.1.9 Surfactants and other contaminants from the environment can be transferred to
10、membrane switch components duringhandling. These contaminants can adversely affect the results of this test.1 This test method is under the jurisdiction of ASTM Committee F01 on Electronics, and is the direct responsibility of Subcommittee F01.18 on Membrane Switches.Current edition approved July 1,
11、 2006Oct. 1, 2014. Published July 2006November 2014. Originally approved in 1999. Last previous edition approved in 20012006 asF199601.06. DOI: 10.1520/F1996-06.10.1520/F1996-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. F
12、or Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may
13、not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor
14、 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Apparatus6.1 Closed Environmental System , with temperature and humidity control (see Practice F1596).6.2 Current-Limiting DC Power Source. (Series current limiting resistor may be used with dc power supply).6.3 Milliamp Meter (
15、see Test Method F1689).6.4 Megohm Meter.6.5 Test Surface, flat, smooth, unyielding, nonporous, and larger than switch under test.7. Procedure7.1 Pretest Setup:7.1.1 Test specimen(s) shall be permitted to stabilize at 20 to 25C and 40 to 60 % relative humidity (RH) for a minimum of24 h.7.2 Test Setup
16、 (Fig. 1):7.2.1 Secure switch on test surface and measure initial insulation resistance between test points and record results. Protectconnector as necessary (see 5.1.5).7.2.2 Orient switch and flex tail in positions that simulate the end use application positions unless otherwise specified. The fle
17、xtail orientation (bent down, up or back) may differ from the orientation of the switch (horizontal, vertical or angled).7.2.3 Connect power supply leads to test points.7.3 In Process Test:7.3.1 Apply voltage to the test points. Limit the current to prevent high current from disintegrating the dendr
18、ites caused by silvermigration. Use a current limiting resistor to limit the current to 2 milliamps or less. (See Fig. 1)7.3.2 Expose test specimen(s) to specified temperature and humidity while under electrical load for a specified duration, (forexample, 10 days at 55C/85 % RH). The ramp rate to th
19、e specified test set points (temperature and humidity) should be chosento maintain a non-condensing environment.7.3.3 After specified duration disconnect power supply and remove from chamber. Allow to stabilize following 7.1.1.7.4 Post Test:7.4.1 Measure final insulation resistance between test poin
20、ts and record results.7.4.2 An insulation resistance measurement below specified value constitutes a failure of this test.7.4.3 If a failure, inspect visually (without magnification) for staining or discoloration.FIG. 1 Test SetupF1996 1428. Report8.1 Report the following information:8.1.1 Humidity,
21、8.1.2 Temperature,8.1.3 Voltage,8.1.4 Current limit value,8.1.5 Specified duration,8.1.6 Schematic of unit under test indicating circuit connections and polarity,8.1.7 Initial insulation resistance, final insulation resistance, pass/fail,8.1.8 Results of visual inspection,8.1.9 Mounting substrate an
22、d orientation of switch and flex during test, and8.1.10 Note if flex tail connector is sealed and with what potting material.9. Keywords9.1 membrane switch; silver dendrite; silver migrationASTM International takes no position respecting the validity of any patent rights asserted in connection with
23、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 responsibility.This standard is subject to revision at any time by the responsible technic
24、al 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 addressed to ASTM International Headquarters. Your comments will receive careful consideration
25、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 address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor
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