ASTM F140-98(2003)
(Practice)Standard Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods
Standard Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods
SIGNIFICANCE AND USE
The term “reference” as employed in this practice implies that either the glass or the metal of the reference glass-metal seal will be a “standard reference material” such as those supplied for other physical tests by the National Institute for Standards and Technology (NIST), or a secondary reference material whose sealing characteristics have been determined by seals to a standard reference material.5 Until standard reference materials for seals are established by the NIST, secondary reference materials may be agreed upon between manufacturer and purchaser.
SCOPE
1.1 This practice covers the preparation and testing of reference glass-metal butt seals of two general configurations: one applicable to determining stress in the glass and the other to determining the degree of mismatch of thermal expansion (or contraction). Tests are in accordance with Test Method F 218 (Section 1.1).
1.2 This practice applies to all glass and metal (or alloy) combinations normally sealed together in the production of electronic components. It should not be attempted with glass-metal combinations having widely divergent thermal expansion (or contraction) properties.
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Designation: F 140 – 98 (Reapproved 2003)
Standard Practice for
Making Reference Glass-Metal Butt Seals and Testing for
Expansion Characteristics by Polarimetric Methods
This standard is issued under the fixed designation F 140; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope those supplied for other physical tests by the National Institute
forStandardsandTechnology(NIST),orasecondaryreference
1.1 This practice covers the preparation and testing of
materialwhosesealingcharacteristicshavebeendeterminedby
reference glass-metal butt seals of two general configurations:
sealstoastandardreferencematerial. Untilstandardreference
one applicable to determining stress in the glass and the other
materials for seals are established by the NIST, secondary
to determining the degree of mismatch of thermal expansion
reference materials may be agreed upon between manufacturer
(or contraction). Tests are in accordance with Test Method
and purchaser.
F218 (Section 1.1).
1.2 This practice applies to all glass and metal (or alloy)
5. Apparatus
combinations normally sealed together in the production of
5.1 Polarimeter, as specified in Test Method F218 for
electronic components. It should not be attempted with glass-
measuring optical retardation and analyzing stress in glass.
metal combinations having widely divergent thermal expan-
5.2 Cut-Off Saw, with diamond-impregnated wheel and No.
sion (or contraction) properties.
180 grit abrasive blade under flowing coolant for cutting and
2. Referenced Documents fine-grinding glass rod.
5.3 Glass Polisher, buffing wheel with cerium oxide polish-
2.1 ASTM Standards:
ing powder or laboratory-type equipment with fine-grinding
F47 TestMethodforCrystallographicPerfectionofSilicon
and polishing laps.
by Preferential Etch Techniques
5.4 Heat-Treating and Oxidizing Furnaces, with suitable
F79 Specification for Type 101 Sealing Glass
controls and with provisions for appropriate atmospheres
F105 Specification forType 58 Borosilicate Sealing Glass
(Annex A1) for preconditioning metal, if required.
F218 Test Method for Analyzing Stress in Glass
5.5 Sealing Furnace, radiant tube, muffle or r-f induction
3. Summary of Practice
with suitable controls and provision for use with inert atmo-
sphere.
3.1 Five seals of a standard configuration are prepared from
5.6 Annealing Furnace, with capability of controlled cool-
representative specimens of the glass and metal to be tested.
ing.
The glass and metal are cleaned, treated, and sized to specified
5.7 Ultrasonic Cleaner, optional.
proportions. Plane-interfaced seals are formed, annealed, and
5.8 Fixture for Furnace Sealing, designed as suggested in
measured for residual optical retardation. The stress parallel to
Annex A2.
the interface in each seal is calculated from the optical
5.9 Micrometer Caliper, with index permitting direct read-
retardation, and the average stress is computed for the sample.
ing accuracy of 0.02 cm.
For disk-seals the thermal expansion mismatch is calculated.
5.10 Immersion Mercury Thermometer.
4. Significance and Use
6. Materials
4.1 The term “reference” as employed in this practice
6.1 Metal—Representative specimen pairs of the metal
implies that either the glass or the metal of the reference
from either rod or plate stock with dimensions satisfying the
glass-metalsealwillbea“standardreferencematerial”suchas
requirements of 7.2 or 7.3.The surfaces to be sealed should be
relatively free of scratches, machine marks, pits, or inclusions
that would induce localized stresses. The sealing surfaces
This practice is under the jurisdiction ofASTM Committee C14 on Glass and
Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical should terminate in sharp edges at the peripheral corners to act
and Mechanical Properties.
as a glass stop. Edges that are rounded, such as appear on
Current edition approved Oct. 10, 1998. Published January 1999. Originally
tumbled parts, will have the tendency to permit glass overflow.
e1
approved in 1971. Last previous edition approved in 1995 as F140–83 (1995) .
Annual Book of ASTM Standards, Vol 10.05.
Annual Book of ASTM Standards, Vol 15.02.
4 5
Annual Book of ASTM Standards, Vol 10.04. See NIST SP260.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 140 – 98 (2003)
6.2 Glass—Representative specimens of rod or plate glass,
cut with either diamond-impregnated or other abrasive cutting
wheelsunderflowingwater.Dimensions(volume)shallsatisfy
the requirements of 7.2 or 7.3.
7. Test Specimen
7.1 Two basic cylindrical geometries are considered. For
determining only the stress in glass, a seal whose total length
is at least twice its diameter must be used. For determining
expansion mismatch (as well as stress) a seal whose total
thickness is equal to or less than one fifth of its diameter must
be used.
7.2 The design for measuring stress provides seals between
a cylindrical rod specimen of glass and metal of either rod or
sheet (strip) form. The standard rod seal of Fig. 1(a) shall be
made from specimens so that the diameter of the metal, d , is
m
FIG. 2 Sheet Seals
0.5 to 1.0 mm larger than the diameter of the glass, d , before
g
the seal is made; the lengths l and l shall each be at least d .
g m g
The standard sheet seal of Fig. 2(a) shall be made from
specimens so that l is at least 10 l and a and b each exceed
g m
d by at least 1.0 mm. In all cases d shall be at least 5.0 mm;
g g
disdefinedasthesightingline(orlightpath)throughtheglass
at the interface after sealing.
7.2.1 Record the dimensions of glass and metal.
7.3 For determining the thermal expansion mismatch be-
tween the metal and the glass, the standard disk seal shown in
Fig.3(a)ismade.Here d mayexceed d by0.5to1.0mm; d
m g g
shallbeatleast10mm.Themetaltoglassthicknessratio,t /t ,
m g
may range from ⁄3 to 1; d is defined as the sighting line (or
light path) through the glass at the interface after sealing and
must be at least 5 (t + t ).
m g
FIG. 3 Disk Seals
7.3.1 Record the dimensions of glass and metal.
8. Preparation of Specimens
NOTE 1—Thecleanedandheat-treatedmetalshouldbesealedwithin24
8.1 Metal—Chemically clean the specimens to remove
h and should be protected from surface contamination during this period.
surface contaminants, especially lubricants and fingerprints
8.2 Glass—Using optical-glass techniques grind and polish
from fabrication and handling. Usually it is advisable to
the sealing surface of the glass specimens with either wet
preoxidize parts as described in Annex A1. Preoxidation
abrasive wheels or water slurries of abrasive on a lap. The
promotes a better glass-to-metal bond and relieves cold-
polishedsurfaceshouldbeat90 62°tothespecimenaxisand
working stresses.
without chips, nicks, or scratches. Remove any surface con-
taminants which could produce bubbly seals. An ultrasonic
wash may be used (Annex A1).
8.3 Measure and record the dimensions (diameter, length,
thickness) of each glass and each metal specimen.
9. Procedure for Making the Butt-Seal
9.1 Record dimensions of metal plates and glass parts.
9.2 Make the seal in a furnace, by flame, or by induction
heating of the metal, utilizing suitable specimen holders or
supports under controlled conditions of temperature and time
(Annex A2).
10. Annealing
10.1 Once a symmetrical, bubble-free seal has been made,
proper annealing of the seal becomes the most critical part of
the procedure. It is by this operation that all stresses are
relieved except those due to the difference in thermal contrac-
FIG. 1 Rod Seals tion of the two materials from annealing temperature levels.
F 140 – 98 (2003)
This process involves heating the seal to a temperature to the nearest 0.1°C the temperature of the liquid using an
somewhat higher than the annealing point of the glass and immersion mercury thermometer.
maintaining the temperature for a time sufficient to relieve the 11.1.4 Record the type of light source and the effective
existing strain. The test specimen is then cooled slowly at a wavelength, L, in nanometres of the light for which the
constant rate.As an alternative, annealing can proceed directly retardation has been measured. Record the interface extinction
on cooling during the making of a seal. angle and sense (tension or compression) as defined in Test
10.2 Seal stress and associated expansion mismatch can be Method F218.
varied markedly by annealing schedule modification. For this 11.1.5 Measure the length d along the light path (Fig. 1, 2,
reason, when the test is used as an acceptance specification, it and 3) using a micrometer caliper with an index permitting
is strongly recommended that producer and user mutually direct reading of 0.002 mm.
definetheannealingscheduleandestablishrigidcontrolsforits
12. Calculations
maintenance.
12.1 Calculate the retardation per unit length of each speci-
11. Procedure for Measuring Optical Retardation
men as follows:
11.1 For each specimen measure the retardation in the
R5LA/180d (1)
annealed seal due to the stress parallel to the interface
where:
according to Test Method F218.
R = retardation per unit length, nm/nm,
11.1.1 Position the cylindrical axis of the glass (in an
L = wavelength of light source, nm,
immersion liquid, if needed) in a direction 45° from the
A = rotation of analyzer, deg, and
direction of vibration of the polarizer and analyzer, so that the
d = length of the light path through the interface, nm.
line of sight or light path lies in the plane of the interface and
´
12.2 Calculate the average, R, of the values of R for the
passes through its center.
specimens in a test lot.
11.1.2 Determine the retardation along the light path in
12.3 For each test lot, calculate the average seal stress
termsofdegreesofrotationoftheanalyzer.Rotatetheanalyzer
parallel to the interface using the relationship:
in a direction that causes the curved black fringe seen within
the glass to appear to move up to but not beyond the
S5R/K (2)
glass-metal interface (as though into the metal). Rotate the
where:
analyzer so that any light or “gray” area whi
...
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