ASTM_F_111_-_96_2002.pdf

Designation:F 111 96(Reapproved 2002)Standard Practice forDetermining Barium Yield,Getter Gas Content,and GetterSorption Capacity for Barium Flash Getters1This standard is issued under the fixed designation F 111;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice describes techniques for the determinationof evaporated barium yield,getter gas content,and gettercarbon monoxide sorption capacity for barium flash gettersused in electron devices.Test conditions are chosen to approxi-mate use conditions.1.2 Auxiliary procedures for cleaning,for determiningvacuum system leak-up rates,for flashing getters,and fordetermining barium content in both getter fill and films are alsogiven.1.3 The various tests described are destructive in nature.Ingeneral the tests are semiquantitative but they can be expectedto yield comparative information on a single-laboratory basisto the precision indicated.No information relative to multi-laboratory reproducibility is available.1.4 List of Methods Described:MethodSectionBarium Content,Determination of,9Acid-Base Titration Method9.6Complexation(Titration)Method9.7Gravimetric Method9.4Photometric Method9.5Weight Difference Method9.8Barium Yield,Determination of,10Carbon Monoxide Sorption Characteristics,Determination of12Cleaning Procedures6Getter Mount6.3Getter Test Bulb6.4Flashing Procedures8Gas Content,Determination of for Doped Getters:11Hydrogen11.7Nitrogen for Undoped Getters:11.8Preflash Gas Content11.5Total Gas Content11.4Leak-Up Rates,Determination of71.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 4.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water23.Terminology3.1 Definitions of Terms Specific to this Standard:3.1.1 barium flash gettersused to remove residual gasespresent after exhaust or generated during device operation bysorption with a barium film produced by heating the getter.3.1.2 barium yield,Mthe weight of barium in milligramsevaporated when a getter is flashed.Flash conditions arespecified in terms of start time and total time.3.1.2.1 start time,tsthe interval in seconds between theapplication of heating power and the onset of barium evapo-ration.This value depends on the power applied.3.1.2.2 total time,ttthe full interval in seconds duringwhich heating power is applied to the getter.3.1.3 carbon monoxide sorption capacity,Cthe quantityof CO sorbed at room temperature(25C)measured inmillitorr-litres until the terminal gettering rate is reached.3.1.4 conductance,Fof a system for a given gas or vaporis the ratio of throughput of gas,Q,to the partial pressuredifference across the system,P2 P1,in the steady state.It ismeasured in liters per second,and given by F=Q/(P2 P1)where P2is the upstream pressure,and P1is the downstreampressure.3.1.5 flashingthe evaporation of barium,contained withina getter,as a consequence of induction or resistance heating ofthe getter.3.1.6 Gas Content:3.1.6.1 preflash gas content,PGCthe quantity of gas inmillitorr-litres reported as nitrogen equivalent evolved at flash-ing after it has been degassed at 350C for 15 min under kineticvacuum conditions.3.1.6.2 total gas content,TGCof a getter is the quantity ofgas in millitorr-litres reported as nitrogen equivalent evolved atflashing when a getter is heated from room temperature.1This practice is under the jurisdiction of ASTM Committee F01 on Electronicsand is the direct responsibility of Subcommittee F01.03 on Metallic Materials.Current edition approved June 10,1996.Published August 1996.Originallypublished as F 111 69 T.Last previous edition F 111 72(1991).2Annual Book of ASTM Standards,Vol 11.01.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.3.1.7 getter mounta mechanical device used to secure thegetter and its integral support leg(if any)at the specifiedposition in the getter test bulb.3.1.8 gettering rate,Gdefined as the volume of gassorbed in 1 s and is measured in litres per second.3.1.8.1 terminal getter ratereached when the getteringrate decreases to 1 L/s for large(TV)getters or 0.1 L/s forsmall(receiving tube)getters.It is used to define the end pointof the CO sorption capacity test.3.1.9 getter test bulbthat portion of the apparatus inwhich the getter is flashed(see Table 1 and Table 2).3.1.10 mass throughput,Qthe quantity of gas flowingthrough a given plane in unit time and is measured inmillitorr-litres per second.3.1.11 molecular flow