ASTM F140-98
(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
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 Method F218 (Section 2).
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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 140 – 98
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. 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 for Standards and Technology (NIST), or a secondary reference
material whose sealing characteristics have been determined by
1.1 This practice covers the preparation and testing of
seals to a standard reference material. Until standard reference
reference glass-metal butt seals of two general configurations:
materials for seals are established by the NIST, secondary
one applicable to determining stress in the glass and the other
reference materials may be agreed upon between manufacturer
to determining the degree of mismatch of thermal expansion
and purchaser.
(or contraction). Tests are in accordance with Test Method
F 218 (Section 1.1).
5. Apparatus
1.2 This practice applies to all glass and metal (or alloy)
5.1 Polarimeter, as specified in Test Method F 218 for
combinations normally sealed together in the production of
measuring optical retardation and analyzing stress in glass.
electronic components. It should not be attempted with glass-
5.2 Cut-Off Saw, with diamond-impregnated wheel and No.
metal combinations having widely divergent thermal expan-
180 grit abrasive blade under flowing coolant for cutting and
sion (or contraction) properties.
fine-grinding glass rod.
2. Referenced Documents 5.3 Glass Polisher, buffing wheel with cerium oxide polish-
ing powder or laboratory-type equipment with fine-grinding
2.1 ASTM Standards:
and polishing laps.
F 47 Test Method for Crystallographic Perfection of Silicon
2 5.4 Heat-Treating and Oxidizing Furnaces, with suitable
by Preferential Etch Techniques
controls and with provisions for appropriate atmospheres
F 79 Specification for Type 101 Sealing Glass
3 (Annex A1) for preconditioning metal, if required.
F 105 Specification for Type 58 Borosilicate Sealing Glass
5.5 Sealing Furnace, radiant tube, muffle or r-f induction
F 218 Test Method for Analyzing Stress in Glass
with suitable controls and provision for use with inert atmo-
3. Summary of Practice
sphere.
5.6 Annealing Furnace, with capability of controlled cool-
3.1 Five seals of a standard configuration are prepared from
ing.
representative specimens of the glass and metal to be tested.
5.7 Ultrasonic Cleaner, optional.
The glass and metal are cleaned, treated, and sized to specified
5.8 Fixture for Furnace Sealing, designed as suggested in
proportions. Plane-interfaced seals are formed, annealed, and
Annex A2.
measured for residual optical retardation. The stress parallel to
5.9 Micrometer Caliper, with index permitting direct read-
the interface in each seal is calculated from the optical
ing accuracy of 0.02 cm.
retardation, and the average stress is computed for the sample.
5.10 Immersion Mercury Thermometer.
For disk-seals the thermal expansion mismatch is calculated.
6. Materials
4. Significance and Use
6.1 Metal—Representative specimen pairs of the metal
4.1 The term “reference” as employed in this practice
from either rod or plate stock with dimensions satisfying the
implies that either the glass or the metal of the reference
requirements of 7.2 or 7.3. The surfaces to be sealed should be
glass-metal seal will be a “standard reference material” such as
relatively free of scratches, machine marks, pits, or inclusions
those supplied for other physical tests by the National Institute
that would induce localized stresses. The sealing surfaces
should terminate in sharp edges at the peripheral corners to act
as a glass stop. Edges that are rounded, such as appear on
This practice is under the jurisdiction of ASTM Committee C-14 on Glass and
Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical
tumbled parts, will have the tendency to permit glass overflow.
and Mechanical Properties.
6.2 Glass—Representative specimens of rod or plate glass,
Current edition approved Oct. 10, 1998. Published January 1999. Originally
e1 cut with either diamond-impregnated or other abrasive cutting
published as F 140 – 71 T. Last previous edition F 140 – 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 SP 260.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 140
wheels under flowing water. Dimensions (volume) shall satisfy
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
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
FIG. 2 Sheet Seals
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
d is defined as the sighting line (or light path) through the glass
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) is made. Here d may exceed d by 0.5 to 1.0 mm; d
m g g
shall be at least 10 mm. The metal to glass thickness ratio, 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
7.3.1 Record the dimensions of glass and metal.
8. Preparation of Specimens
FIG. 3 Disk Seals
8.1 Metal—Chemically clean the specimens to remove
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-
polished surface should be at 90 6 2° to the specimen axis and
working stresses.
without chips, nicks, or scratches. Remove any surface con-
taminants which could produce bubbly seals. An ultrasonic
NOTE 1—The cleaned and heat-treated metal should be sealed within 24
wash may be used (Annex A1).
h and should be protected from surface contamination during this period.
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-
tion of the two materials from annealing temperature levels.
This process involves heating the seal to a temperature
somewhat higher than the annealing point of the glass and
FIG. 1 Rod Seals maintaining the temperature for a time sufficient to relieve the
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 140
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 F 218.
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.
define the annealing schedule and establish rigid controls for its
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 F 218.
R 5 retardation per unit length, nm/nm,
11.1.1 Position the cylindrical axis of the glass (in an
L 5 wavelength of light source, nm,
immersion liquid, if needed) in a direction 45° from the
A 5 rotation of analyzer, deg, and
direction of vibration of the polarizer and analyzer, so that the
d 5 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
terms of degrees of rotation of the analyzer. Rotate the analyzer
parallel to the interface using the relationship:
in a direction that causes the curved black fringe seen within
S5R/K (2)
the glass to appear to move up to but not beyond the
glass-metal interface (as though into the metal). Rotate the
where:
analyzer so that any light or “gray” area which may exist
S 5 stress parallel to interface, Pa,
between the darkest part of the fringe (its center of width) and
R 5 average retardation per unit length of the test speci-
the surface of the metal disappears; this condition is termed
mens, nm/nm, and
“extinction.” When e
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.