ASTM F14-80(2000)
(Practice)Standard Practice for Making and Testing Reference Glass-Metal Bead-Seal
Standard Practice for Making and Testing Reference Glass-Metal Bead-Seal
SCOPE
1.1 This practice covers procedures for preparing and testing reference glass-to-metal bead-seals for determining the magnitude of thermal expansion (or contraction) mismatch between the glass and metal. Tests are in accordance with method F218 (2).
1.2 This practice applies to all glass-metal combinations, established or experimental, particularly those intended for electronic components.
1.3 The practical limit of the test in devising mismatch is approximately 300 ppm, above which the glass is likely to fracture.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use .
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Designation:F14–80 (Reapproved 2000)
Standard Practice for
Making and Testing Reference Glass-Metal Bead-Seal
ThisstandardisissuedunderthefixeddesignationF 14;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Summary of Practice
1.1 This practice covers procedures for preparing and test- 3.1 Seals of a standard configuration are prepared from a
ing reference glass-to-metal bead-seals for determining the representative sample of each metal and glass to be tested.
magnitude of thermal expansion (or contraction) mismatch Each material is prepared by an approved method and sized as
between the glass and metal. Tests are in accordance with specified. The seal is formed, annealed, and measured for
method F218 (2). optical retardation from which the axial stress and expansion
1.2 This practice applies to all glass-metal combinations, mismatch are calculated. At least two specimens are required
established or experimental, particularly those intended for from which average values are obtained.
electronic components.
4. Significance and Use
1.3 The practical limit of the test in devising mismatch is
4.1 The term reference as employed in this practice implies
approximately 300 ppm, above which the glass is likely to
fracture. that both the glass and the metal of the reference glass-metal
seal will be a standard reference material such as those
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the supplied for other physical tests by the National Institute of
Standards and Technology, or a secondary reference material
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- whose sealing characteristics have been determined by seals to
a standard reference material (see NIST Special Publication
bility of regulatory limitations prior to use.
260). Until standard reference materials for seals are estab-
2. Referenced Documents
lished by the NIST, secondary reference materials may be
2.1 ASTM Standards: agreed upon between producer and user.
C 770 Test Method for Measurement of Glass Stress-
2 5. Apparatus
Optical Coefficient
5.1 Polarimeter, as specified in Method F 218 for measur-
F 15 Specification for Iron-Nickel-Cobalt Sealing Alloy
F 30 Specification for Iron-Nickel Sealing Alloys ing optical retardation and analyzing stress in glass.
5.2 Heat-Treating and Oxidizing Furnaces, with suitable
F 31 Specification for 42 % Nickel-6 % Chromium-Iron
Sealing Alloy controls and with provisions for appropriate atmospheres
(Annex A1) for preconditioning metal, if required.
F 79 Specification for Type 101 Sealing Glass
F 105 Specifications for Type 58 Borosilicate Sealing 5.3 Glassworking Lamp or Sealing Furnace, radiant tube,
muffle, or r-f induction with suitable controls and provision for
Glass
F 218 Test Method for Analyzing Stress in Glass use with inert atmosphere.
5.4 Annealing Furnace, with capability of controlled cool-
F 256 Specification for Chromium-Iron SealingAlloys with
18 or 28 % Chromium ing.
5.5 Ultrasonic Cleaner, optional.
F 257 Specifications for 28 % Chromium-Iron Alloy for
Sealing to Glass 5.6 Micrometer Caliper, with index permitting direct read-
ing of 0.02 cm.
This practice is under the jurisdiction of ASTM Committee C14 on Glass and
Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical
and Mechanical Properties.
Current edition approved Nov. 10, 1995. Published January 1996. Originally
1 5
published as F14 – 61 T. Last previous edition F 14 – 80 (1991)e . Available from NIST Standard Reference Materials, Gaithersburg, MD 20899.
2 6
Annual Book of ASTM Standards, Vol 15.02. Gulati, S. T., and Hagy, H. E., “Expansion Measurement Using Short
Annual Book of ASTM Standards, Vol 10.04. Cylindrical Seal:Theory and Measurement,”ThermalExpansion6, edited by Ian D.
Discontinued, see 1973 Annual Book of ASTM Standards, Part 6. Peggs, Plenum, New York, N. Y., 1978, pp. 113–130.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F14–80 (2000)
6. Materials 9. Procedure for Measuring Optical Retardation
6.1 Metal—Representative rod stock with out-of-round not 9.1 For each specimen measure the retardation in the
exceeding 1 % shall be selected, preferably with a diameter in annealed seal at the glass-metal interface parallel to the seal
the range 0.5 to 4 mm. Smaller diameters result in a loss of axis in accordance with Method F 218.
sensitivity and larger diameters tend to be cumbersome and 9.1.1 Placethesealinanindex-matchingliquidandposition
impractical. Surfaces shall be relatively free of scratches, its axis in a direction 45° from the direction of vibration of the
machine marks, pits, or inclusions that would induce localized polarizer and analyzer, so that the line of sight is at the
stresses. Length requirements are discussed in 6.2. midpoint of the glass bead.
6.2 Glass—Representative glass tubing of suitable optical 9.1.2 Determine the retardation along the light path through
transmission with an inside diameter 0.15 to 0.25 mm larger the glass in terms of degrees of rotation of the analyzer. Rotate
than the metal rod diameter.The outside diameter of the tubing in a direction that causes the black fringe seen within the glass
shall preferably be such that it produces a glass-to-metal to move toward the glass-metal interface. Stop rotation of the
diameterratiobetween1.5and2.Thelengthofthetubingshall analyzer when the center of the black fringe is coincident with
exceed four times the finished glass diameter.The length of the the glass-metal interface. This condition is termed the point of
metal rod must exceed the length of the tubing. Surface extinction.
contaminants shall be removed to reduce the risk of making
NOTE 1—Sealing combinations may exist in which the thermal expan-
bubbly seals. An ultrasonic water mark is recommended.
sion coefficients of glass and metal at room temperature may differ
significantly. In these cases it may be important to record the temperature
7. Seal-Making Procedure
of the refraction liquid (or the seal) at the time the retardation is measured.
7.1 The seal may be made either by flame-working tech-
9.1.3 Repeat the above for a total of four measurements per
niques or by heating the tubing-rod assembly in a furnace. I
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