1、Designation: F144 80 (Reapproved 2010)Standard Practice forMaking Reference Glass-Metal Sandwich Seal and Testingfor Expansion Characteristics by Polarimetric Methods1This standard is issued under the fixed designation F144; the number immediately following the designation indicates the year of orig
2、inaladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the preparation and testing of areference g
3、lass-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 F218 (Section 2).1.2 This practice applies to all glass and metal (or alloy)combinations normal
4、ly 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 is th
5、eresponsibility 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-Nicke
6、l Sealing AlloysF31 Specification for 42 % Nickel-6 % Chromium-IronSealing AlloyF47 Test Method for Crystallographic Perfection of Siliconby Preferential Etch Techniques3F79 Specification for Type 101 Sealing GlassF105 Specification for Type 58 Borosilicate Sealing GlassF218 Test Method for Measurin
7、g Optical Retardation andAnalyzing Stress in GlassF256 Specification for Chromium-Iron Sealing Alloys with18 or 28 Percent 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
8、, treated, and sized to specifiedproportions. 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 t
9、he sample.4. Significance 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 Technolog
10、y, or a secondary reference 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 manufac
11、turer and purchaser.5. Apparatus5.1 Polarimeter, as specified in Test Method F218 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 Polis
12、her, buffing wheel with 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 Furnac
13、e, radiant tube, muffle or r-f inductionwith suitable controls and provision for use with inert atmo-sphere.5.6 Annealing Furnace, with capability of controlled cool-ing.1This practice is under the jurisdiction of ASTM Committee C14 on Glass andGlass Products and is the direct responsibility of Subc
14、ommittee C14.04 on Physicaland Mechanical Properties.Current edition approved April 1, 2010. Published May 2010. Originallyapproved in 1971T. Last previous edition approved in 2005 as F144 80 (2005).DOI: 10.1520/F0144-80R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
15、act ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Ha
16、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.7 Ultrasonic Cleaner, optional.5.8 Fixture for Furnace 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 MetalF
17、ive representative specimen pairs of the metalfrom either rod or plate stock with dimensions satisfying therequirements of 7.1. The surfaces to be sealed should berelatively free of scratches, machine marks, pits, or inclusionsthat would induce localized stresses. The sealing surfacesshould terminat
18、e in sharp edges at the peripheral corners to actas a glass stop. Edges that are rounded, such as appear ontumbled parts, will have 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 wi
19、th either diamond-impregnated or other abrasivecutting wheels under flowing water. Dimensions (volume)must satisfy the requirements 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,squar
20、e, or rectangular plates. In each case the dimension d, Fig.1, designates the path along which the optical retardation in thefinished 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/tm
21、should be atleast 6.7.2 Glass with suitable optical transmission of any shapemay be used, provided it flows essentially bubble-free 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 ou
22、tline of the metal plates. Thethickness of the glass before sealing shall be such that it equalstmafter sealing within 15 %. Thus, 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 t
23、he glass.7.3 When used as an acceptance test by producer and user,the number of test seals representing one determination shall beestablished by mutual agreement. However two seals are aminimum requirement for one determination.8. Preparation of Specimens8.1 MetalChemically clean the specimens to re
24、movesurface contaminants, especially lubricants and fingerprintsfrom fabrication and handling. Usually it is advisable topreoxidize 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
25、polishthe sealing surfaces of the glass specimens with either wetabrasive wheels or water slurries of abrasive on a lap. Thepolished 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 se
26、als. Anultrasonic wash may be used. See Annex A1.9. Procedure for Making the Sandwich Seal9.1 Record dimensions of metal plates and 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
27、 and time. See Annex A2.10. Annealing10.1 Once a symmetrical, bubble-free seal has been made,proper annealing of the seal becomes 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 materi
28、als from annealing temperature levels.This process involves heating the seal to a temperaturesomewhat higher than the annealing point 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 alt
29、ernative, annealing can proceed directlyon cooling during the making of a seal.10.2 Seal stress and associated expansion mismatch can bevaried markedly by annealing schedule modification. For thisreason, when the test is used as an acceptance specification, itis strongly recommended that producer an
30、d user mutuallydefine the annealing schedule and establish rigid controls for itsmaintenance.11. Procedure for Measuring Optical Retardation11.1 For each specimen measure the retardation in theannealed seal due to the stress parallel to the interfaceaccording to Test Method F218.11.1.1 Position the
31、plane of the seal (in an immersion liquid,if needed) in a direction 45 from the direction of vibration ofthe polarizer and analyzer, 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 di
32、ameter.11.1.2 Determine the retardation along the light paththrough the glass in terms of degrees of rotation of analyzer.Rotate in a direction that causes the curved black fringes seenwithin the glass to appear to merge in the center of crosssection of the glass and away from the glassmetal interfa
33、ces.Rotate the analyzer so that any light or “gray” area which mayexist between the fringes disappears and a dark spot, or area, isformed. This condition is termed the point of extinction.FIG. 1 Permissible Metal Shapes.FIG. 2 General Seal Configuration.F144 80 (2010)2NOTE 1Sealing combinations may
34、exist in which the thermal expan-sion coefficients of glass and metal at room temperature may differsignificantly. In these cases 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 com
35、positions containingmore than one alkali oxide, part of the retardation observed may not beassociated with the mismatch stress of interest. In these cases somestructural birefringence is caused by temporary stresses at elevatedtemperatures. Evaluate the exact analysis of mismatch stress by com-plete
36、ly removing the metal member by acid immersion. Read again theretardation at the same glass surface. Then algebraically subtract 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 recor
37、dthe temperature of the immersion liquid to the nearest 1Cusing an immersion mercury thermometer.11.1.4 Record the type of light source and the effectivewavelength, L, in nanometers, of the light for which theretardation has been measured. Record the interface positionand the major stress component
38、position and sense (tension orcompression) as defined in Test Method F218.11.1.5 Measure the length d along the light path (Fig. 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 un
39、it length, nm/cm,L = wavelength of light source, nm,A = rotation of analyzer, deg, andd = length of the light path through the 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
40、 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 For 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 retardatio
41、n per unit length of the testspecimens, nm/cm, andK = stress-optical coefficient of the glass, nm/cmPa.NOTE 4The stress-optical coefficient K of any reference glass shall besupplied by the producer. Values for typical sealing glasses are found inTable A1 of Specifications F79 and F105.12.4 Calculate
42、 the thermal expansion mismatch (the differ-ential thermal contraction between the glass and the metal fromthe setting point (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 g
43、lass, respec-tively, cm,Emand Eg= Youngs modulus of metal and glass,respectively, Pa,k = shape factor (see Fig. 3)4and,v = composite Poissons ratio, given by:FIG. 3 Shape FactorF144 80 (2010)3v 5Stg2tmDvg1SEmEgDS1 1 vg1 1 vmDvmFtg2tm1S1 1 vg1 1 vmDEmEgG(4)where vgand vmare glass and metal Poissons r
44、atios,respectively.13. Report13.1 The report shall include the following:13.1.1 Type of metal and identification,13.1.2 Type 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 ligh
45、t path through glass at the center ofcross section near the interface for each specimen,13.1.7 Stress-optical coefficient of 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 measurement
46、s or, if noimmersion liquid is used, the temperature of the seal, and13.1.10 Average value, range, and sense of thermal expan-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 Cl
47、ean the glass with ultrasonic agitation in 0.5 60.01 % nonionic wetting agent solution at 50 6 5C for 5 6 1min. If necessary, 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
48、distilled or deionized water and alcohol. Blowdry with nitrogen or filtered air, and then oven dry at 110 65C for 15 6 2 min. 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). Degre
49、ase these alloys intrichloroethylene vapor or liquid, and follow this with theultrasonic cleaning procedure in A1.1. Rinse 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 F256A1.3 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 m
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