ASTM F140-98(2013)

Standard Practice for<brk type="line"/> Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods

SIGNIFICANCE AND USE
4.1 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.4 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 F218 (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.

General Information

• Status: Historical
• Publication Date: 30-Sep-2013
• ICS: 21.140 - Seals, glands
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.04 - Physical and Mechanical Properties

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F140 − 98 (Reapproved 2013)
Standard Practice for
Making Reference Glass-Metal Butt Seals and Testing for
Expansion Characteristics by Polarimetric Methods
ThisstandardisissuedunderthefixeddesignationF140;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope retardation, and the average stress is computed for the sample.
For disk-seals the thermal expansion mismatch is calculated.
1.1 This practice covers the preparation and testing of
reference glass-metal butt seals of two general configurations:
4. Significance and Use
one applicable to determining stress in the glass and the other
4.1 The term “reference” as employed in this practice
to determining the degree of mismatch of thermal expansion
implies that either the glass or the metal of the reference
(or contraction). Tests are in accordance with Test Method
glass-metalsealwillbea“standardreferencematerial”suchas
F218 (Section 1.1).
those supplied for other physical tests by the National Institute
1.2 This practice applies to all glass and metal (or alloy)
forStandardsandTechnology(NIST),orasecondaryreference
combinations normally sealed together in the production of
materialwhosesealingcharacteristicshavebeendeterminedby
electronic components. It should not be attempted with glass-
sealstoastandardreferencematerial. Untilstandardreference
metal combinations having widely divergent thermal expan-
materials for seals are established by the NIST, secondary
sion (or contraction) properties.
reference materials may be agreed upon between manufacturer
and purchaser.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
5.1 Polarimeter, as specified in Test Method F218 for
F47Test Method for Crystallographic Perfection of Silicon
measuring optical retardation and analyzing stress in glass.
by Preferential Etch Techniques (Withdrawn 1998)
F79Specification for Type 101 Sealing Glass
5.2 Cut-Off Saw, with diamond-impregnated wheel and No.
F105Specification for Type 58 Borosilicate Sealing Glass
180 grit abrasive blade under flowing coolant for cutting and
F218Test Method for Measuring Optical Retardation and
fine-grinding glass rod.
Analyzing Stress in Glass
5.3 Glass Polisher, buffing wheel with cerium oxide polish-
ing powder or laboratory-type equipment with fine-grinding
3. Summary of Practice
and polishing laps.
3.1 Five seals of a standard configuration are prepared from
5.4 Heat-Treating and Oxidizing Furnaces, with suitable
representative specimens of the glass and metal to be tested.
controls and with provisions for appropriate atmospheres
The glass and metal are cleaned, treated, and sized to specified
(Annex A1) for preconditioning metal, if required.
proportions. Plane-interfaced seals are formed, annealed, and
measured for residual optical retardation.The stress parallel to 5.5 Sealing Furnace, radiant tube, muffle or r-f induction
the interface in each seal is calculated from the optical
with suitable controls and provision for use with inert atmo-
sphere.
5.6 Annealing Furnace, with capability of controlled cool-
This practice is under the jurisdiction ofASTM Committee C14 on Glass and
ing.
Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical
and Mechanical Properties.
5.7 Ultrasonic Cleaner, optional.
Current edition approved Oct. 1, 2013. Published October 2013. Originally
approved in 1971. Last previous edition approved in 2008 as F140–98 (2008).
5.8 Fixture for Furnace Sealing, designed as suggested in
DOI: 10.1520/F0140-98R13.
Annex A2.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.9 Micrometer Caliper, with index permitting direct read-
Standards volume information, refer to the standard’s Document Summary page on
ing accuracy of 0.02 cm.
the ASTM website.
The last approved version of this historical standard is referenced on
www.astm.org. See NIST SP260.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F140 − 98 (2013)
5.10 Immersion Mercury Thermometer.
6. Materials
6.1 Metal—Representativespecimenpairsofthemetalfrom
either rod or plate stock with dimensions satisfying the
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
should terminate in sharp edges at the peripheral corners to act
as a glass stop. Edges that are rounded, such as appear on
tumbled parts, will have the tendency to permit glass overflow.
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.
FIG. 2 Sheet Seals
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
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
FIG. 3 Disk Seals
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.
d shall be at least 10 mm. The metal to glass thickness ratio,
7.2.1 Record the dimensions of glass and metal. g
t /t , may range from ⁄3 to 1; d is defined as the sighting line
m g
7.3 For determining the thermal expansion mismatch be-
(or light path) through the glass at the interface after sealing
tween the metal and the glass, the standard disk seal shown in
and must be at least 5 (t + t ).
m g
Fig. 3(a) is made. Here d may exceed d by 0.5 to 1.0 mm;
m g
7.3.1 Record the dimensions of glass and metal.
8. Preparation of Specimens
8.1 Metal—Chemically clean the specimens to remove sur-
face contaminants, especially lubricants and fingerprints from
fabrication and handling. Usually it is advisable to preoxidize
partsasdescribedinAnnexA1.Preoxidationpromotesabetter
glass-to-metal bond and relieves cold-working stresses.
NOTE1—Thecleanedandheat-treatedmetalshouldbesealedwithin24
h and should be protected from surface contamination during this period.
8.2 Glass—Using optical-glass techniques grind and polish
the sealing surface of the glass specimens with either wet
abrasive wheels or water slurries of abrasive on a lap. The
polishedsurfaceshouldbeat90 62°tothespecimenaxisand
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,
FIG. 1 Rod Seals thickness) of each glass and each metal specimen.
F140 − 98 (2013)
associated with the mismatch stress of interest. In these cases some
9. Procedure for Making the Butt-Seal
structural birefringence is caused by temporary stresses at elevated
9.1 Record dimensions of metal plates and glass parts.
temperatures. The exact analysis of mismatch stress should be evaluated
by completely removing the metal member by acid immersion. The
9.2 Make the seal in a furnace, by flame, or by induction
retardation should again be read at the same glass surface. Any residual
heating of the metal, utilizing suitable specimen holders or
retardation should then be algebraically subtracted from that previously
supports under controlled conditions of temperature and time
observed.
(Annex A2). NOTE 4—If it is desired to minimize any uncertainties about measuring
through the curved surfaces, these may be ground after annealing to
10. Annealing
conformtothealternateshapesofFig.1(b),2(b),or3(b).Opposingfaces
shouldbegroundsoastobeparalleltoeachotherandnormaltotheplane
10.1 Once a symmetrical, bubble-free seal has been made,
ofthesealinterfaceeachwithin ⁄2°.Forrodsealsorsheetseals,grinding
proper annealing of the seal becomes the most critical part of
should be such that in Fig. 1( b) and 2(b) the dimension d is not less than
the procedure. It is by this operation that all stresses are 0.8 d . In the case of the alternative disk seal of Fig. 3(b), d must still be
g
at least 5(t + t ). Grinding should be followed by reannealing before
relieved except those due to the difference in thermal contrac- m g
measuring retardation. It should be borne in mind that grinding may
tion of the two materials from annealing temperature levels.
produce micro or macro cracks at the interface with the uncertainties
This process involves heating the seal to a temperature
associated with these conditions.
somewhat higher than the annealing point of the glass and
11.1.3 If an immersion liquid is used record the nominal
maintaining the temperature for a time sufficient to relieve the
index of refraction, n , of the liquid, and measure and record
D
existing strain. The test specimen is then cooled slowly at a
to the nearest 0.1°C the temperature of the liquid using an
constant rate.As an alternative, annealing can proceed directly
immersion mercury thermometer.
on cooling during the making of a seal.
11.1.4 Record the type of light source and the effective
10.2 Seal stress and associated expansion mismatch can be
wavelength, L, in nanometres of the light for which the
varied markedly by annealing schedule modification. For this
retardation has been measured. Record the interface extinction
reason, when the test is used as an acceptance specification, it
angle and sense (tension or compression) as defined in Test
is strongly recommended that producer and user mutually
Method F218.
definetheannealingscheduleandestablishrigidcontrolsforits
11.1.5 Measure the length d along the light path (Fig. 1,2,
maintenance.
and 3) using a micrometer caliper with an index permitting
direct read
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