1、Designation: F 144 80 (Reapproved 2005)Standard Practice forMaking Reference Glass-Metal Sandwich Seal and Testingfor Expansion Characteristics by Polarimetric Methods1This standard is issued under the fixed designation F 144; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the preparation and testing of areferenc
3、e glass-metal sandwich seal for determining stress inthe glass or for determining the degree of thermal expansion(or contraction) mismatch between the glass and metal. Testsare in accordance with Test Method F 218 (Section 2).1.2 This practice applies to all glass and metal (or alloy)combinations no
4、rmally sealed together in the production ofelectronic components.1.3 The practical limit of the test in deriving mismatch isapproximately 300 ppm, above which the glass is likely tofracture.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its use. It i
5、s theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F15 Specification for Iron-Nickel-Cobalt Sealing AlloyF30 Specification for Iron-N
6、ickel Sealing AlloysF31 Specification for 42 Percent Nickel-6 % Chromium-Iron Sealing AlloyF47 Test Method for Crystallographic Perfection of Siliconby Preferential Etch Techniques3F79 Specification for Type 101 Sealing GlassF 105 Specification for Type 58 Borosilicate Sealing GlassF 218 Test Method
7、 for Analyzing Stress in GlassF 256 Specification for Chromium-Iron Sealing Alloys with18 or 28 % Chromium3. Summary of Practice3.1 Seals of a standard configuration are prepared fromrepresentative specimens of the glass and metal to be tested.The glass and metal are cleaned, treated, and sized to s
8、pecifiedproportions. Plane-interfaced seals are formed, annealed, andmeasured for residual optical retardation. The stress parallel tothe interface in each seal is calculated from the opticalretardation, and the average stress and thermal expansionmismatch are computed for the sample.4. Significance
9、 and Use4.1 The term “reference” as employed in this practiceimplies that either the glass or the metal of the referenceglass-metal seal will be a “standard reference material” such asthose supplied for other physical tests by the National Instituteof Standards and Technology, or a secondary referen
10、ce materialwhose sealing characteristics have been determined by seals toa standard reference material (see NBS Special Publication260). Until standard reference materials for seals are estab-lished by the NIST, secondary reference materials may beagreed upon between manufacturer and purchaser.5. Ap
11、paratus5.1 Polarimeter, as specified in Test Method F 218 formeasuring optical retardation and analyzing stress in glass.5.2 Cut-Off Saw, with diamond-impregnated wheel and No.180 grit abrasive blade under flowing coolant for cutting andfine-grinding glass rod.5.3 Glass Polisher, buffing wheel with
12、cerium oxide polish-ing powder or laboratory-type equipment with fine-grindingand polishing laps.5.4 Heat-Treating and Oxidizing Furnaces, with suitablecontrols and with provisions for appropriate atmospheres(Annex A1) for preconditioning metal, if required.5.5 Sealing Furnace, radiant tube, muffle
13、or r-f inductionwith suitable controls and provision for use with inert atmo-sphere.1This practice is under the jurisdiction of ASTM Committee C14 on Glass andGlass Products and is the direct responsibility of Subcommittee C14.04 on Physicaland Mechanical Properties.Current edition approved Sept. 1,
14、 2005. Published October 2005. Originallyapproved in 1971T. Last previous edition approved in 2000 as F 144 80(2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to
15、 the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.6 Annealing Furnace, with capability of controlled cool-ing.5.7 Ultrasonic Cleaner, optional.5.8 Fixture for Furnace
16、 Sealing, design as suggested inAnnex A2.5.9 Micrometer Caliper, with index permitting direct read-ing of 0.02 cm.5.10 Immersion Mercury Thermometer.6. Materials6.1 MetalFive representative specimen pairs of the metalfrom either rod or plate stock with dimensions satisfying therequirements of 7.1. T
17、he surfaces to be sealed should berelatively free of scratches, machine marks, pits, or inclusionsthat would induce localized stresses. The sealing surfacesshould terminate in sharp edges at the peripheral corners to actas a glass stop. Edges that are rounded, such as appear ontumbled parts, will ha
18、ve the tendency to permit glass overflow.The opposite faces of each plate should be parallel within 0.5.6.2 GlassFive representative specimens of rod or plateglass, cut with either diamond-impregnated or other abrasivecutting wheels under flowing water. Dimensions (volume)must satisfy the requiremen
19、ts of 7.2, and the faces should beflat and parallel within 0.5 for uniform flow during sealing.7. Test Specimens7.1 The metal specimens may take the form of circular,square, or rectangular plates. In each case the dimension d, Fig.1, designates the path along which the optical retardation in thefini
20、shed seal is measured. Two identical metal plates of any ofthe indicated shapes are required for a seal. The thickness, tm,of each plate should be at least 0.7 mm and d/tmshould be atleast 6.7.2 Glass with suitable optical transmission of any shapemay be used, provided it flows essentially bubble-fr
21、ee to fill theentire volume between the metal plates as in Fig. 2. Experienceindicates, however, that best results are obtained with flat glassconforming closely to the outline of the metal plates. Thethickness of the glass before sealing shall be such that it equalstmafter sealing within 15 %. Thus
22、, the volume of glassnecessary to fill the void between the metal plates to athickness equal to that of a single plate becomes the determin-ing dimensional criterion for the glass.7.3 When used as an acceptance test by producer and user,the number of test seals representing one determination shall b
23、eestablished by mutual agreement. However two seals are aminimum requirement for one determination.8. Preparation of Specimens8.1 MetalChemically clean the specimens to removesurface contaminants, especially lubricants and fingerprintsfrom fabrication and handling. Usually it is advisable topreoxidi
24、ze parts as described in Annex A1. Preoxidationpromotes a better glass-to-metal bond and relieves cold work-ing stresses.8.2 GlassUsing optical glass techniques grind and polishthe sealing surfaces of the glass specimens with either wetabrasive wheels or water slurries of abrasive on a lap. Thepolis
25、hed surfaces should satisfy the dimensional criteria of 6.2and 7.2, and be without chips, nicks, or scratches. Remove anysurface contaminants which could produce bubbly seals. Anultrasonic wash may be used. See Annex A1.9. Procedure for Making the Sandwich Seal9.1 Record dimensions of metal plates a
26、nd glass parts.9.2 Make the seal in a furnace or by induction heating of themetal utilizing suitable specimen holders or supports undercontrolled conditions of temperature and time. See Annex A2.10. Annealing10.1 Once a symmetrical, bubble-free seal has been made,proper annealing of the seal becomes
27、 the most critical part ofthe procedure. It is by this operation that all stresses arerelieved 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 temperaturesomewhat higher than the annealing p
28、oint of the glass andmaintaining this temperature for a time sufficient to relieve theexisting strain. The test specimen is then cooled slowly at aconstant rate. As an alternative, annealing can proceed directlyon cooling during the making of a seal.10.2 Seal stress and associated expansion mismatch
29、 can bevaried markedly by annealing schedule modification. For thisreason, when the test is used as an acceptance specification, itis strongly recommended that producer and user mutuallydefine the annealing schedule and establish rigid controls for itsmaintenance.11. Procedure for Measuring Optical
30、Retardation11.1 For each specimen measure the retardation in theannealed seal due to the stress parallel to the interfaceaccording to Test Method F 218.11.1.1 Position the plane of the seal (in an immersion liquid,if needed) in a direction 45 from the direction of vibration ofthe polarizer and analy
31、zer, so that the line of sight, or lightpath, is through the maximum glass dimension in the directiond shown in Fig. 1. In a circular seal, for example, this would bethe diameter.11.1.2 Determine the retardation along the light paththrough the glass in terms of degrees of rotation of analyzer.Rotate
32、 in a direction that causes the curved black fringes seenwithin the glass to appear to merge in the center of crossFIG. 1 Permissible Metal Shapes.FIG. 2 General Seal Configuration.F 144 80 (2005)2section of the glass and away from the glassmetal interfaces.Rotate the analyzer so that any light or “
33、gray” area which mayexist between the fringes disappears and a dark spot, or area, isformed. This condition is termed the point of extinction.NOTE 1Sealing combinations may exist in which the thermal expan-sion coefficients of glass and metal at room temperature may differsignificantly. In these cas
34、es it may be important to record the temperatureof the refraction liquid (or the seal) at the time the retardation is measured.NOTE 2In certain glasses, especially those compositions containingmore than one alkali oxide, part of the retardation observed may not beassociated with the mismatch stress
35、of interest. In these cases somestructural birefringence is caused by temporary stresses at elevatedtemperatures. Evaluate the exact analysis of mismatch stress by com-pletely removing the metal member by acid immersion. Read again theretardation at the same glass surface. Then algebraically subtrac
36、t anyresidual retardation from that previously observed.11.1.3 If an immersion liquid is used record the nominalindex of refraction, nD, of the liquid, and measure and recordthe temperature of the immersion liquid to the nearest 1Cusing an immersion mercury thermometer.11.1.4 Record the type of ligh
37、t source and the effectivewavelength, L, in nanometers, of the light for which theretardation has been measured. Record the interface positionand the major stress component position and sense (tension orcompression) as defined in Test Method F 218.11.1.5 Measure the length d along the light path (Fi
38、g. 1)using a micrometer caliper.12. Calculations12.1 Calculate the retardation per unit length of each speci-men as follows:R 5 L3 A!/180 3 d! (1)where:R = retardation per unit length, nm/cm,L = wavelength of light source, nm,A = rotation of analyzer, deg, andd = length of the light path through the
39、 interface, cm.NOTE 3In determining the light path only that length of glass sealedat the interface is considered. In a complete seal, this may be the same asd of Fig. 1, but it may be less. See A2.6 of Annex A2.12.2 Calculate the average, R, of the values of R for thespecimens in a test lot.12.3 Fo
40、r each test lot, calculate the average seal stressparallel to the interface using the relationship:S 5 R/K (2)where:S = stress parallel to interface, Pa,R= average retardation per unit length of the testspecimens, nm/cm, andK = stress-optical coefficient of the glass, nm/cmPa.NOTE 4The stress-optica
41、l coefficient K of any reference glass shall besupplied by the producer. Values for typical sealing glasses are found inTable A1 of Specifications F 79 and F 105.12.4 Calculate the thermal expansion mismatch (the differ-ential thermal contraction between the glass and the metal fromthe setting point
42、 (approximately the strain point) of the glass toroom temperature) as follows:d5S 1 2 kv!2FtgEmtm12EgG106(3)where:d = expansion mismatch, ppm,tmand tg= thickness of metal and glass, respec-tively, cm,FIG. 3 Shape FactorF 144 80 (2005)3Emand Eg= Youngs modulus of metal and glass,respectively, Pa,k =
43、shape factor (see Fig. 3)4and,v = composite Poissons ratio, given by:v 5Stg2tmDvg1SEmEgDS1 1 vg1 1 vmDvmFtg2tm1S1 1 vg1 1 vmDEmEgG(4)where vgand vmare glass and metal Poissons ratios,respectively.13. Report13.1 The report shall include the following:13.1.1 Type of metal and identification,13.1.2 Typ
44、e of glass and identification,13.1.3 Dimensions of metal plate and glass for each speci-men,13.1.4 Number of specimens tested,13.1.5 Annealing schedule,13.1.6 Length of the light path through glass at the center ofcross section near the interface for each specimen,13.1.7 Stress-optical coefficient o
45、f the glass,13.1.8 Type of light source and effective wavelength,13.1.9 Nominal index of refraction of immersion liquid andits temperature at the time of retardation measurements or, if noimmersion liquid is used, the temperature of the seal, and13.1.10 Average value, range, and sense of thermal exp
46、an-sion mismatch.414. Keywords14.1 expansion mismatch; glass-metal sealsANNEXESA1. DIRECTIONS FOR CLEANING AND HEAT-TREATING SPECIMENS OF GLASS AND METAL FOR MAKING SEALSA1.1 Clean the glass with ultrasonic agitation in 0.5 60.01 % nonionic wetting agent solution at 50 6 5C for 5 6 1min. If necessar
47、y, precede this by an immersion in a 15 %aqueous hydrofluoric acid5solution for 0.15 to 1 min; this isrecommended particularly for aged or weathered glass. Rinsesuccessively in distilled or deionized water and alcohol. Blowdry with nitrogen or filtered air, and then oven dry at 110 65C for 15 6 2 mi
48、n. Rinse water (distilled or deionized) shallhave a resistivity greater than 2 M Vcm.A1.2 Commonly used ASTM sealing alloys are Fe-Ni-Co,Fe-Ni, Ni-Cr-Fe, and Cr-Fe (A1.1). Degrease these alloys intrichloroethylene vapor or liquid, and follow this with theultrasonic cleaning procedure in A1.1. Rinse
49、in water. Immersein 10 6 1 % hydrochloric acid solution at 1006 5C for 2 60.5 min and follow this with the final rinsing and dryingprocedure in A1.1.NOTE A1.1These sealing alloys are covered by the following ASTMspecifications:Alloy SpecificationFe-Ni-Co F15Fe-Ni F30Ni-Cr-Fe F31Cr-Fe F 256A1.3 Heat treat Fe-Ni-Co and Fe-Ni alloys in wet (satu-rated) hydrogen at 1100 6 20C for 30 6 2 min. Then oxidizein air at 800 6 10C for 8 6 2 min. As a result of oxidationFe-Ni-Co should gain 0.2 to 0.4 mg/cm2in weight; Fe-Nishould gain 0.1 to 0.3 mg/cm2in weight.A1
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