Designation:F204−76(Reapproved2013)StandardTestMethodforSurfaceFlawsinTungstenSealRodandWire1ThisstandardisissuedunderthefixeddesignationF204;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationofthepres-enceofsurfaceflawsintungsten-sealrodandwireofrandomorcutlengths,andinthetungstensectionofmultiple-piece-throughleadsusedinelectronicdevices,bymeansofexami-nationofaglassbeadsealedtothetungsten.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.Terminology2.1Definitions:2.1.1beadedlength—theactuallengththroughwhichaglass-to-tungstensealexistsasevidencedbythecoloroftheinterface.2.1.2fault—atungsten-glasssealinwhichafissure,eitherdelineatedbyalineofbubblesorinitselfclearlydiscernible,isobservedwheninspectedasprescribedinthistestmethod.2.1.3fissure—anynarrowopeningorcleftinthesurfaceofthetungsten.2.1.4lineofbubbles—onelongorseveralsmallbubblessoarrangedintheotherwisesubstantiallybubble-freeglassbeadthattheyareinanalmoststraightlineimmediatelyadjacenttothetungsten-glassinterface.3.Apparatus3.1BeadingEquipment—Suitablebeadingequipmentca-pableofproducingglass-to-tungstensealsasprescribedinSection4.3.2Microscope—Alow-powermicroscopecapableofmag-nificationupto30diameters,preferablyofthebinoculartype.3.3LightSource—Asuitablewhitelightsource,preferablydiffuseforilluminationofthebeadunderthemicroscope.4.PreparationofTestSpecimen4.1Thetestspecimenshallbeabeadedtungstenrodpreparedinthefollowingmanner:4.1.1Cleanthesurfacetobebeadedi...
