ASTM F111-96

Standard Practice for Determining Barium Yield, Getter Gas Content, and Getter Sorption Capacity for Barium Flash Getters

SCOPE
1.1 This practice describes techniques for the determination of evaporated barium yield, getter gas content, and getter carbon monoxide sorption capacity for barium flash getters used in electron devices. Test conditions are chosen to approximate use conditions.
1.2 Auxiliary procedures for cleaning, for determining vacuum system leak-up rates, for flashing getters, and for determining barium content in both getter fill and films are also given.
1.3 The various tests described are destructive in nature. In general the tests are semiquantitative but they can be expected to yield comparative information on a single-laboratory basis to the precision indicated. No information relative to multilaboratory reproducibility is available.
1.4 List of Methods DescribedMethodSectionBarium 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 of7
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 4.

General Information

• Status: Historical
• Publication Date: 09-Jun-1996
• Technical Committee: F01 - Electronics
• Drafting Committee: F01.03 - Metallic Materials, Wire Bonding, and Flip Chip

Relations

• Replaced By: ASTM F111-96(2002) - Standard Practice for Determining Barium Yield, Getter Gas Content, and Getter Sorption Capacity for Barium Flash Getters (Withdrawn 2008)
• Effective Date: 10-Jun-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 111 – 96
Standard Practice for
Determining Barium Yield, Getter Gas Content, and Getter
Sorption Capacity for Barium Flash Getters
This standard is issued under the fixed designation F 111; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice describes techniques for the determination 2.1 ASTM Standards:
of evaporated barium yield, getter gas content, and getter D 1193 Specification for Reagent Water
carbon monoxide sorption capacity for barium flash getters
3. Terminology
used in electron devices. Test conditions are chosen to approxi-
3.1 Definitions of Terms Specific to this Standard:
mate use conditions.
1.2 Auxiliary procedures for cleaning, for determining 3.1.1 barium flash getters—used to remove residual gases
present after exhaust or generated during device operation by
vacuum system leak-up rates, for flashing getters, and for
sorption with a barium film produced by heating the getter.
determining barium content in both getter fill and films are also
given. 3.1.2 barium yield, M—the weight of barium in milligrams
evaporated when a getter is flashed. Flash conditions are
1.3 The various tests described are destructive in nature. In
general the tests are semiquantitative but they can be expected specified in terms of start time and total time.
3.1.2.1 start time, t —the interval in seconds between the
to yield comparative information on a single-laboratory basis
s
to the precision indicated. No information relative to multi- application of heating power and the onset of barium evapo-
ration. This value depends on the power applied.
laboratory reproducibility is available.
1.4 List of Methods Described: 3.1.2.2 total time, t —the full interval in seconds during
t
which heating power is applied to the getter.
Method Section
Barium Content, Determination of, 9
3.1.3 carbon monoxide sorption capacity, C—the quantity
Acid-Base Titration Method 9.6
of CO sorbed at room temperature (25°C) measured in
Complexation (Titration) Method 9.7
millitorr-litres until the terminal gettering rate is reached.
Gravimetric Method 9.4
Photometric Method 9.5
3.1.4 conductance, F—of a system for a given gas or vapor
Weight Difference Method 9.8
is the ratio of throughput of gas, Q, to the partial pressure
Barium Yield, Determination of, 10
difference across the system, P − P , in the steady state. It is
Carbon Monoxide Sorption Characteristics, Determination of 12
2 1
Cleaning Procedures 6
measured in liters per second, and given by F = Q/(P −P )
2 1
Getter Mount 6.3
where P is the upstream pressure, and P is the downstream
2 1
Getter Test Bulb 6.4
pressure.
Flashing Procedures 8
Gas Content, Determination of 11
3.1.5 flashing—the evaporation of barium, contained within
for Doped Getters:
a getter, as a consequence of induction or resistance heating of
Hydrogen 11.7
the getter.
Nitrogen 11.8
for Undoped Getters:
3.1.6 Gas Content:
Preflash Gas Content 11.5
3.1.6.1 preflash gas content, PGC—the quantity of gas in
Total Gas Content 11.4
millitorr-litres reported as nitrogen equivalent evolved at flash-
Leak-Up Rates, Determination of 7
ing after it has been degassed at 350°C for 15 min under kinetic
1.5 This standard does not purport to address all of the
vacuum conditions.
safety concerns, if any, associated with its use. It is the
3.1.6.2 total gas content, TGC—of a getter is the quantity of
responsibility of whoever uses this standard to consult and
gas in millitorr-litres reported as nitrogen equivalent evolved at
establish appropriate safety and health practices and deter-
flashing when a getter is heated from room temperature.
mine the applicability of regulatory limitations prior to use.
3.1.7 getter mount—a mechanical device used to secure the
Specific hazard statements are given in Section 4.
getter and its integral support leg (if any) at the specified
position in the getter test bulb.
3.1.8 gettering rate, G—defined as the volume of gas
This practice is under the jurisdiction of ASTM Committee F-1 on Electron- sorbed in 1 s and is measured in litres per second.
icsand is the direct responsibility of Subcommittee F01.03 on Metallic Materials.
Current edition approved June 10, 1996. Published August 1996. Originally
published as F 111 – 69 T. Last previous edition F 111 – 72 (1991). Annual Book of ASTM Standards, Vol 11.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 111
TABLE 2 Bulbs and Coils for Determination of CO Sorption
3.1.8.1 terminal getter rate—reached when the gettering
Characteristics
rate decreases to 1 litre/s for large (TV) getters or 0.1 L/s for
small (receiving tube) getters. It is used to define the end point
Getter Type Test Bulb Test Bulb Dimensions Coil
of the CO sorption capacity test.
3.1.9 getter test bulb—that portion of the apparatus in
Receiving tube spherical bulb 100-cm spherical flask F
which the getter is flashed (see Table 1 and Table 2).
(all) (OD 60 mm)
3.1.10 mass throughput, Q—the quantity of gas flowing OD 12–13 mm standard TV bulb 12-in., 110° neck, OD 20 E
TV mm
through a given plane in unit time and is measured in
OD 18–19 mm standard TV bulb 19-in., 114° neck, OD 28.5 F
millitorr-litres per second.
TV mm
OD 25–26 mm standard TV bulb 23-in., 92° neck, OD 36.5 F
3.1.11 molecular flow region—that pressure region where
A
TV mm H
gases or vapors flow under conditions such that the largest
A
Used for antenna-mounted getters.
internal dimension of a transverse section of the vessel is
smaller than the mean free path. Under these conditions the
used in electron devices. The major components of a getter are:
rate of flow is limited not by collisions between molecules but
the fill, the container, and the support.
by collisions of molecules with the walls.
5.1.1 The Getter Fill is based on barium alloy, BaAl ,to
3.1.12 sorption by a getter—the process of removing gases 4
minimize the reactions of barium with the atmosphere.
and vapors by adsorption and absorption phenomena.
5.1.1.1 An endothermic getter fill uses the BaAl alloy alone
3.1.12.1 Absorption, deals with gas interactions in the bulk 4
and requires continued heating above 1050°C to liberate and
of the getter film and is dependent on diffusion rates, solubility,
evaporate the barium.
and chemical reactions.
5.1.1.2 An exothermic getter fill is produced by intimately
3.1.12.2 adsorption—describes gas interactions at the sur-
mixing about four moles of nickel with one mole of the barium
face of the getter film.
alloy. On heating to about 800°C, the nickel reacts exother-
3.1.12.3 Quantities of sorbed gas are measured in millitorr-
mally with the alloy, liberating and evaporating 10 to 30 % of
litres.
the barium. Continued heating is required to evaporate most of
4. Safety Hazards
the remaining barium.
4.1 Eye protection is mandatory in the presence of large
5.1.1.3 The getter may be gas doped. Hydrogen may be
evacuated glass vessels or picture-tube bulbs, which should
added to the fill for reported beneficial effects on electron
also be surrounded by suitable mechanical protection against
emission. Nitrogen may be added to influence the distribution
implosion.
and to produce a more porous film and thereby increase the gas
sorption capacity as measured below.
5. Test Specimens
5.1.2 The Getter Container form depends on the method of
5.1 The test specimens are commercial barium flass getters
supplying heating power for flashing.
5.1.2.1 If resistance heating is to be used it should have an
TABLE 1 Suggested Bulb and Coil Dimensions
open geometry, more or less rectilinear.
NOTE 1—The getters are centered in both coaxial and tangential coils.
5.1.2.2 If induction heating is to be used it should have the
form of a closed loop. The present trend is to employ a
Bulb
ring-shaped channel. In such cases the getter-channel cross
Outside
A
Getter Type
Length, Height,
section may be varied to influence, to a certain extent, the
Number Diameter,
mm mm
mm getter film-deposition pattern.
5.1.3 A Getter Support is used for mounting and position-
Coaxial Flashing:
ing the getter in electron devices. It may or may not be an
Receiving tube A 20 100 35
integral part of the getter.
TV black and white B 35 250 150
5.2 Nominal getter sizes which are currently available are
TV color C 60 320 140
Tangential Flashing (optional):
listed in Appendix X1.
B C
TV color D 80 320 90
5.3 Getter Description—The getter manufacturer shall fur-
nish on request the following data:
Coil
5.3.1 Type of fill (endothermic or exothermic).
Inside
Getter Type
Height,
5.3.2 Recommended yield, start, and total times.
Number Diameter, Tuns
mm
5.3.3 If gas doped or not. If doped, then with which gas; and
mm
the maximum temperature time condition which causes no loss
Coaxial Flashing:
of doping.
Receiving tube E 23 16 3.5
5.3.4 Container size (outside diameter in millimetres for
TV black and white F 51 22 5.5
ring getters; length times width, each in millimetres, for loop
TV color G 70 22 5.5
Tangential Flashing (optional): getters; and length, in millimetres for resistance-heated get-
D
TV color H 51 15 6.0
ters).
A
Measured from bottom of getter to dome of bulb.
5.3.5 Container (channel) shape (ring with high inside wall,
B
Bulb axis inclined 30° from the vertical.
C ring with high outside wall, ring with equal height walls, getter
Measured from center of getter to dome of bulb.
D
A two-layer coil with three turns per layer. tubing, etc.).
F 111
5.3.6 If magnetic or antimagnetic. minimize hydrocarbon contamination.
5.3.7 Shape of support (ribbon, wire, tab).
7. Leak-Up Rates
5.3.8 Special features such as ceramic spacers, etc., if any.
5.4 Getter Lot Number—To any getter production batch a
7.1 Significance—The leak-up rate gives a measure of the
lot number is assigned and the production date is given. From
cleanliness and freedom from leaks of vacuum system.
the lot number, date, and the internal manufacturer’s control
7.2 Summary—The vacuum test chamber which contains a
charts it shall be possible to trace back all the production cycles
pressure gage is isolated from the vacuum pumps by a suitable
up to the incoming raw materials.
valve and the changes in pressure with time are recorded to
5.5 Specimen Handling:
obtain the data needed to calculate leak-up rates. A gas burst
5.5.1 Handle getters only with clean tools, lint free gloves,
may be observed initially on closing the valve due to the
or finger cots, never with bare hands.
liberation of sorbed gases in the valve, but the pressure will
5.5.2 For long term storage, store the getters in a phospho- reach a steady-state value within several seconds. The pressure
rus pentoxide air desiccator or equivalent. As soon as the getter
may then continue to rise in a manner controlled by any real
can is opened, place getters to be tested in a conventional silica leaks and relatively high vapor pressure contaminants within
gel desiccator. Initiate all measurement between 24 and 48 h
the vacuum chamber. The pressure may decrease with time
after placing the getters in the conventional silica gel desicca- indicating a clean leak-free system and pressure-gage pump-
tor.
ing.
7.3 Procedure:
6. Cleaning Procedures
7.3.1 Measure the leak-up rate during the determinations of
gas content (11.4.4) and sorption capacity (12.4.7). The appa-
6.1 Scope—The following cleaning procedures shall be
ratus used is described in these sections. At the appropriate
used for getter mounts and getter test bulbs used in Sections 10,
stage of these determinations, indicated in the relevant text,
11, and 12.
valve off the test chamber from the vacuum pumps and record
6.2 Significance—Cleaning procedures are necessary not
the initial pressure P . After a time, t, record the final pressure
only to ready the mount and bulb for the tests but also to i
P .
minimize possible errors. A residue of barium can cause errors
f
7.3.2 The value of P and P should be such that there is a
in the barium yield determination when chemical methods are f i
reasonable difference between them. Allow a change of at least
used. Oils and greases can adversely effect the vacuum.
a factor of 2 in pressure unless the leak-up rate is extremely
6.3 Materials and Reagents:
low.
6.3.1 Hydrochloric Acid (1 + 17)—add 1 part of concen-
7.4 Calculations—Calculate the system leak-up rate, Q ,in
trated HCl (sp gr 1.19) to 17 parts of deionized water. L
millitorr-litres per second using the following equation:
6.3.2 Deionized Water (DIW)—At least 2-MV resistivity.
6.3.3 Acetone, cp.
Q 5 V~P 2 P !/t
L f i
6.3.4 Cleaning Solution—Add 2 volumes of concentrated
where:
HF (sp gr 1.15), 33 volumes of concentrated HNO (sp gr
V = system volume, litres,
1.42), and 2 volumes of surface active agent to 100 volumes of
P = final pressure, mtorr, in the valved-off test chamber,
f
DIW.
P = initial pressure, mtorr, in the valved-off chamber, and
i
6.3.5 Alkylaryl polyether alcohol (OPE—7 to 8) is a liquid,
t = time of pressure rise, s.
nonionic surface active (wetting) agent. It is listed as an
7.5 Sensitivity—Using commercial Bayert-Alpert design
industrial detergent and emulsifier, effective in aqueous min-
−9
ionization gages and controls (10.10 torr most sensitive
eral acids with good hard (glass) surface detergency and low
−8
full-scale range) and a 1-L volume leak-up rates of 1.10
foam. Any such agent, without filler, ionic or nonionic that
mtorr·litres/s are readily measurable.
meets the properties listed above is acceptable.
6.4 Mount Cleaning:
8. Getter Flashing
6.4.1 Wash with HCl (1 + 17).
8.1 Summary of Procedure—Getters are flashed by induc-
6.4.2 Rinse with DIW.
tion or resistance heating using the required power to achieve
6.4.3 Dry with acetone.
the specified start time. This power is applied for the specified
6.4.4 Handle only with clean tools, lint free gloves, or finger
total time. The quantity of barium evaporated can then be
cots.
determined using the analytic methods given in Section 9.
6.5 Getter Test Bulb Cleaning:
8.2 Significance—The barium yield of a getter when flashed
6.5.1 Wash twice with HCl (1 + 17) to dissolve barium.
at the manufacturer’s recommended start and total times is one
6.5.2 Rinse with tap water.
of the factors considered in selecting a particular getter for a
6.5.3 Rinse with acetone to eliminate oils and greases.
specific application. The variation in barium yield caused by
NOTE 1—The acetone may be replaced by the more active cleaning
changes in start and total times are of interest
...