ASTM F1895-1998(2004) Practice for Submersion of a Membrane Switch《薄膜开关浸没的操作规程》.pdf

1、Designation: F 1895 98 (Reapproved 2004)Practice forSubmersion of a Membrane Switch1This standard is issued under the fixed designation F 1895; 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

2、parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice establishes procedures for the submergingof a membrane switch to verify resistance to ingress of aspecified liquid.1.2 This practi

3、ce can also be used to verify the ability of amembrane switch or graphics layer to act as a liquid seal for afinished product.1.3 Additional test methods or practices can be incorporatedto investigate specific results or capabilities.1.4 This practice is a modification of National ElectricalManufact

4、urers Assoc. (NEMA) Publication Number 250-1991Section 6.10, which is a test for submersion of a finishedproduct housing.1.5 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.2. Referenced Documents2.1 National Electrical

5、 Manufacturers Assoc.:NEMA Publication 250-199123. Terminology3.1 Definitions:3.1.1 membrane switchA momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.3.1.2 specified resistancemaximum allowable resistanceas measured between two terminations whose interna

6、l switchcontacts, when held closed, complete a circuit.3.1.3 silver migrationgrowth of fine crystals betweensilver conductors of a thick film circuit due to an ionic reactionto the presence of water and an applied dc voltage potential.4. Significance and Use4.1 The presence of water inside a membran

7、e switch canaffect its mechanical operation or electrical functionality, orboth. Electrical failure can result as short circuits due to silvermigration or exceeding the specified resistance due to oxida-tion.4.2 This practice establishes a procedure to verify the abilityof a membrane switch to resis

8、t the entry of liquid in itself or afinished product, or both. It is useful in identifying designdeficiencies.4.3 Submersion testing may be destructive, therefore anysamples tested should be considered unfit for future use.5. Interferences5.1 External Ventingany deliberate external venting of theswi

9、tch will allow liquid to enter.5.2 Atmospheric Pressuresignificant changes in atmo-spheric pressure during the test or at different facilities mayalter the time in which leakage might occur.5.3 Duration of Testlonger submersion time increases thepossibility of leakage.5.4 Dye Coloringchose a dye col

10、oring that will notchemical attack the materials.6. Apparatus6.1 Tub of sufficient size and depth (w/cover) for the entireswitch, including any mounting surface to be submerged by atleast 1 in. (25.4 mm) or as specified.6.2 An appropriate device of fixture to hold the switch in afixed position.6.3 A

11、ny additional equipment as required by other testmethods employed.7. Test Specimen7.1 The test specimens may be membrane switches with orwithout graphics.7.2 Laminate to specified material or to a rigid clearmaterial (using a clear material will facilitate visual inspec-tion).7.3 Membrane switches o

12、r graphic overlays designed to actas a liquid seal for the finished product are to be applied to arigid material.8. Conditioning8.1 Condition specimens by exposure to ambient conditionsfor 72 h prior to submersion to allow full cure of adhesives.9. Procedure9.1 Pre-Test Setup:9.1.1 Fixture Unit Unde

13、r Test (UUT) horizontally (or asspecified).1This practice is under the jurisdiction of ASTM Committee F01 on Electronicsand is the direct responsibility of Subcommittee F01.18 on Membrane Switches.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1998. Last previous ed

14、ition approved in 1998 as F 1895-1998.2Available from NEMA, 1300 N 17th St., Suite 1847, Rosslyn, VA 22209.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.9.1.2 Fill tub with specified liquid to provide a level ofapproximately 1 in.

15、(25.4 mm) above the uppermost surface ofUUT or as specified.9.1.3 Add dye coloring and stir for consistency (optional).9.1.4 Allow liquid bath to stabilize to ambient temperature.9.2 In-Process Test9.2.1 Test switch for proper function if required.9.2.2 Position UUT in tub using appropriate fixturin

16、g; covertub.9.2.3 Keep UUT submerged for 24 h or as specified.9.2.4 Remove UUT and allow to air dry.9.2.5 Test switch for proper function if required.9.2.6 Perform visual inspection to determine if liquid haspenetrated the UUT.10. Report10.1 Report the following information:10.1.1 Bath temperature,1

17、0.1.2 Liquid used10.1.3 Atmospheric Pressure10.1.4 Duration of Test10.1.5 Physical/Aesthetic Changes10.1.6 Functional Test Data if required.11. Keywords11.1 immersion; membrane switch; submersion; waterimmersionASTM International takes no position respecting the validity of any patent rights asserte

18、d 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 responsibility.This standard is subject to revision at any time by th

19、e 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 addressed to ASTM International Headquarters. Your comments will receive

20、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 address shown below.This standard is copyrighted by ASTM Internat

21、ional, 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).F 1895 98 (2004)2