ASTM F44-95(2000)
(Specification)Standard Specification for Metallized Surfaces on Ceramic
Standard Specification for Metallized Surfaces on Ceramic
SCOPE
1.1 This specification covers requirements for powdered refractory metal coatings produced with or without additives. These coatings are applied to ceramic bodies in order to join ceramic bodies to metals or to other metallized ceramics by means of brazing or soldering. Included in this specification are requirements for a secondary metallic layer which is usually applied over the refractory metal layer.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
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Designation: F 44 – 95 (Reapproved 2000)
Standard Specification for
Metallized Surfaces on Ceramic
ThisstandardisissuedunderthefixeddesignationF44;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 4.1.3 Secondary metal layer on the metallizing (Section 9),
4.1.4 Values for bond strength (Section 10), and
1.1 This specification covers requirements for powdered
4.1.5 Vacuum tightness of brazed metallized ceramic as-
refractory metal coatings produced with or without additives.
semblies (dependent on allowable use of manufacturer’s prod-
These coatings are applied to ceramic bodies in order to join
uct) (Section 11).
ceramic bodies to metals or to other metallized ceramics by
meansofbrazingorsoldering.Includedinthisspecificationare
5. Uniformity of Metallizing
requirements for a secondary metallic layer which is usually
5.1 Either of the following two levels of quality may be
applied over the refractory metal layer.
agreed upon between manufacturer and purchaser, depending
1.2 The values stated in inch-pound units are to be regarded
upon end use, seal area, and geometry.
as the standard. The values given in parentheses are for
5.2 Level A—Less Demanding Application:
information only.
5.2.1 Thin areas where the ceramic substrate can usually be
2. Referenced Documents seen without magnification through the metallizing will be
acceptable only if all of the following conditions are met:
2.1 ASTM Standards:
5.2.1.1 There are no more than two such areas on any one
E 3 Methods of Preparation of Metallographic Specimens
coated band, spot, or pattern detail.
F 19 Test Method for Tension and Vacuum Testing Metal-
5.2.1.2 Their extremities are no closer than 10 % of the total
lized Ceramic Seals
band length to each other.
3. Terminology 5.2.1.3 They are no wider than 10 % of the width of the
band but not exceeding 1 mm.
3.1 Definitions of Terms Specific to This Standard:
5.2.1.4 Theircumulativelengthdoesnotexceed25 %ofthe
3.1.1 ceramics—as referred to in this specification are
total band length.
understood to be inorganic, nonmetallic materials, the major
5.2.2 Defects such as brush marks, screen marks, marks in
phase of which must be crystalline. A glassy intercrystalline
themetallizingleftbyforeignmattersuchaslint,dust,etc.,and
matrix may be present as one of the minor phases.
pits or blisters, will be acceptable if they meet the four
3.1.2 metallizing— on a ceramic, is a process whereby a
conditions outlined in 5.2.1.1 through 5.2.1.4. Such defects
sinteredmatrixofmetalparticlesfirmlyadherestotheceramic.
will also be acceptable if their raised edges do not interfere
3.1.3 refractory metals—those metals with melting points
with proper assembly of the joint.
equal to or higher than that of chromium.Therefore, this group
5.2.3 Projections on metallized surfaces, such as oversized
includes chromium, columbium, molybdenum, rhenium, tanta-
particles or agglomerates will be objectionable if they interfere
lum, and tungsten.
with assembly.
4. Ordering Information
5.2.4 Continuous coatings over sharp edges or corners with
a radius less than ⁄32 in. (0.8 mm) will not be required unless
4.1 The manufacturer and purchaser shall agree upon spe-
by specific agreement between manufacturer and purchaser.
cific quality levels as outlined in the following sections:
5.3 Level B—Demanding Application:
4.1.1 Uniformity of metallizing (Section 5),
5.3.1 Thin areas will be unacceptable where the ceramic
4.1.2 Thickness of metallizing (Section 6),
substrate can be seen through the metallizing when examined
at 403 magnification.
This specification is under the jurisdiction of ASTM Committee F1 on
5.3.2 Defects through which the underlying ceramic can be
Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic
observed, such as brush or screen marks, marks left by foreign
Materials.
matter such as lint or dust, and pits or chips, will be acceptable
Current edition approved Nov. 10, 1995. Published January 1996. Originally
published as F 44 – 68 (1991). only if all of the following conditions are met:
Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 10.04.
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F44
5.3.2.1 There are no more than two such defects on any 9.5 Brightness of clean matte deposits may not be specified.
coated band, spot, or pattern detail. 9.6 Oxide films on the secondary metallic layer will not be
5.3.2.2 Their extremities are not closer together than 10 % cause for rejection.
of the length of the metallized area in which they occur. 9.7 Defectssuchasblistersdevelopedinsubsequentheating
5.3.2.3 They are not wider than 5 % of the width of area nor operations will be acceptable only in 5.2 Level A application
longer than 2 % of the length of area. and only if all the following conditions are met:
5.3.3 Continuous coatings over sharp corners with a radius 9.7.1 There are no more than two blisters on any one coated
less than ⁄32 in. (0.8 mm) will not be required so long as band, spot, or pattern detail.
subsequent plating covers the radius. The specific gap permis- 9.7.2 No blister is closer than 10 % of the total band length
sibleatsuchacornershallbeagreeduponbymanufacturerand to another blister.
purchaser. 9.7.3 Maximum dimension of any blister does not exceed
5.3.4 Projections on metallized surfaces, such as oversize 10 % of the width of the band; in any case not to exceed ⁄32 in.
particles or agglomerates will be objectionable if they interfere (0.8 mm).
with assembly or alignment. 9.8 The secondary metallic layer must adhere to the metal-
lizing underneath to the extent that no separation exists at this
6. Thickness of Metalizing
interference in tension or torque peel tests after sintering of the
6.1 Measure thickness by observation through a calibrated layer in a suitable protective atmosphere.
9.9 Cleanliness such as absence of fingerprints, dirt, etc.,
micrometer eyepiece in a metallurgical microscope. Measure a
polished cross section that is perpendicular to the metallized which may interfere with brazing or soldering, is not a
requirement for acceptance unless agreed upon between manu-
surface. The measurement shall consist of the average of at
least three representative readings taken where the upper and facturer and purchaser.
9.10 When the secondary metallic layer is omitted from the
lower edges of the layer are parallel. Magnification must be at
least4003toobtainsatisfactoryaccuracy.Asuggestedmethod purchaser requirements, the following items shall become a
part of this specification:
for specimen preparation is shown in Appendix X1.
6.2 Thickness of the sinter-fired metallize layer shall range 9.10.1 Metallized surfaces shall be reasonably free from
dirt, grease, fingerprints, etc., in keeping with normal good
from 0.0004 in. (0.01 m
...
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