ASTM_F_1895_-_14.pdf

Designation:F189514Standard Test Method forSubmersion of a Membrane Switch1This standard is issued under the fixed designation F1895;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 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 procedures for the sub-merging of a membrane switch to verify resistance to ingress ofa specified liquid.1.2 This test method can also be used to verify the ability ofa membrane switch or graphics layer to act as a liquid seal fora finished product.1.3 Additional test methods or practices can be incorporatedto investigate specific results or capabilities.1.4 This test method is a modification of National ElectricalManufacturers Assoc.(NEMA)Publication 250-1991 Section6.10,which is a test for submersion of a finished producthousing.1.5 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F1595 Practice for Viewing Conditions for Visual Inspectionof Membrane SwitchesF1663 Test Method for Determining the Capacitance of aMembrane SwitchF1680 Test Method for Determining Circuit Resistance of aMembrane SwitchF1689 Test Method for Determining the Insulation Resis-tance of a Membrane Switch2.2 National Electrical Manufacturers Assoc.:3(NEMA)Publication 250-19913.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 internal 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 membrane 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 test method establishes a procedure to verify theability of a membrane switch to resist the entry of liquid initself or a finished product,or both.It is useful in identifyingdesign deficiencies.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 theswitch 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.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved Jan.1,2014.Published January 2014.Originallyapproved in 1998.Last previous edition approved in 2010 as F1895-10a.DOI:10.1520/F1895-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from National Electrical Manufacturers Association(NEMA),1300N.17th St.,Suite 1752,Rosslyn,VA 22209,http:/www.nema.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.4 Dye Coloringchose a dye coloring that will notchemically 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 Any 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 or 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.8.2 Considerati