Designation:F140−98(Reapproved2013)StandardPracticeforMakingReferenceGlass-MetalButtSealsandTestingforExpansionCharacteristicsbyPolarimetricMethods1ThisstandardisissuedunderthefixeddesignationF140;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversthepreparationandtestingofreferenceglass-metalbuttsealsoftwogeneralconfigurations:oneapplicabletodeterminingstressintheglassandtheothertodeterminingthedegreeofmismatchofthermalexpansion(orcontraction).TestsareinaccordancewithTestMethodF218(Section1.1).1.2Thispracticeappliestoallglassandmetal(oralloy)combinationsnormallysealedtogetherintheproductionofelectroniccomponents.Itshouldnotbeattemptedwithglass-metalcombinationshavingwidelydivergentthermalexpan-sion(orcontraction)properties.2.ReferencedDocuments2.1ASTMStandards:2F47TestMethodforCrystallographicPerfectionofSiliconbyPreferentialEtchTechniques(Withdrawn1998)3F79SpecificationforType101SealingGlassF105SpecificationforType58BorosilicateSealingGlassF218TestMethodforMeasuringOpticalRetardationandAnalyzingStressinGlass3.SummaryofPractice3.1Fivesealsofastandardconfigurationarepreparedfromrepresentativespecimensoftheglassandmetaltobetested.Theglassandmetalarecleaned,treated,andsizedtospecifiedproportions.Plane-interfacedsealsareformed,annealed,andmeasuredforresidualopticalretardation.Thestressparalleltotheinterfaceineachsealiscalculatedfromtheopticalretardation,andtheaveragestressiscomputedforthesample.Fordisk-sealsthethermalexpansionmismatchiscalculated.4.SignificanceandUse4.1Theterm“reference”asemployedinthispracticeimpliesthateithertheglassorthemetalofthereferenceglass-metalsealwillbea“standardreferencematerial”suchasthosesuppliedforotherphysicaltestsbytheNationalInstituteforStandardsandTechnology(NIST),orasecondaryreferencematerialwhos...
