1、Designation: F 140 98 (Reapproved 2008)Standard Practice forMaking Reference Glass-Metal Butt Seals and Testing forExpansion Characteristics by Polarimetric Methods1This standard is issued under the fixed designation F 140; the number immediately following the designation indicates the year oforigin
2、al adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the preparation and testing ofreference glas
3、s-metal butt seals of two general configurations:one applicable to determining stress in the glass and the otherto determining the degree of mismatch of thermal expansion(or contraction). Tests are in accordance with Test MethodF 218 (Section 1.1).1.2 This practice applies to all glass and metal (or
4、 alloy)combinations normally sealed together in the production ofelectronic components. It should not be attempted with glass-metal combinations having widely divergent thermal expan-sion (or contraction) properties.2. Referenced Documents2.1 ASTM Standards:2F47 Test Method for Crystalographic Perfe
5、ction of Siliconby Preferential Etch Techniques3F79 Specification for Type 101 Sealing GlassF 105 Specification for Type 58 Borosilicate Sealing GlassF 218 Test Method for Measuring Optical Retardation andAnalyzing Stress in Glass3. Summary of Practice3.1 Five seals of a standard configuration are p
6、repared fromrepresentative specimens of the glass and metal to be tested.The glass and metal are cleaned, 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 calcula
7、ted from the opticalretardation, and the average stress is computed for the sample.For disk-seals the thermal expansion mismatch is calculated.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
8、be a “standard reference material” such asthose supplied for other physical tests by the National Institutefor Standards andTechnology (NIST), or a secondary referencematerial whose sealing characteristics have been determined byseals to a standard reference material.4Until standard referencemateria
9、ls for seals are established by the NIST, secondaryreference materials may be agreed upon between manufacturerand purchaser.5. Apparatus5.1 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 an
10、d No.180 grit abrasive blade under flowing coolant for cutting andfine-grinding glass rod.5.3 Glass Polisher, 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 p
11、rovisions for appropriate atmospheres(Annex A1) for preconditioning metal, if required.5.5 Sealing Furnace, 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.5.7 Ultrasonic Cleaner, o
12、ptional.5.8 Fixture for Furnace Sealing, designed as suggested inAnnex A2.5.9 Micrometer Caliper, with index permitting direct read-ing accuracy of 0.02 cm.5.10 Immersion Mercury Thermometer.6. Materials6.1 MetalRepresentative specimen pairs of the metalfrom either rod or plate stock with dimensions
13、 satisfying the1This 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 April 1, 2008. Published December 2008 . Originallyapproved in 1971. Last pre
14、vious edition approved in 2003 as F 140 98 (2003).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 the standards Document Summary page onthe ASTM website.3Withdrawn.
15、 The last approved version of this historical standard is referencedon www.astm.org4See NIST SP 260.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.requirements of 7.2 or 7.3. The surfaces to be sealed should berelatively free of scr
16、atches, 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 have the tendency to permit glass overflow.6.2 GlassRepres
17、entative specimens of rod or plate glass,cut with either diamond-impregnated or other abrasive cuttingwheels under flowing water. Dimensions (volume) shall satisfythe requirements of 7.2 or 7.3.7. Test Specimen7.1 Two basic cylindrical geometries are considered. Fordetermining only the stress in gla
18、ss, a seal whose total lengthis at least twice its diameter must be used. For determiningexpansion mismatch (as well as stress) a seal whose totalthickness is equal to or less than one fifth of its diameter mustbe used.7.2 The design for measuring stress provides seals betweena cylindrical rod speci
19、men of glass and metal of either rod orsheet (strip) form. The standard rod seal of Fig. 1(a) shall bemade from specimens so that the diameter of the metal, dm, is0.5 to 1.0 mm larger than the diameter of the glass, dg, beforethe seal is made; the lengths lgand lmshall each be at least dg.The standa
20、rd sheet seal of Fig. 2(a) shall be made fromspecimens so that lgis at least 10 lmand a and b each exceeddgby at least 1.0 mm. In all cases dgshall be at least 5.0 mm;d is defined as the sighting line (or light path) through the glassat the interface after sealing.7.2.1 Record the dimensions of glas
21、s and metal.7.3 For determining the thermal expansion mismatch be-tween the metal and the glass, the standard disk seal shown inFig. 3(a) is made. Here dmmay exceed dgby 0.5 to 1.0 mm; dgshall be at least 10 mm.The metal to glass thickness ratio, tm/tg,may range from13 to 1; d is defined as the sigh
22、ting line (orlight path) through the glass at the interface after sealing andmust be at least 5 (tm+ tg).7.3.1 Record the dimensions of glass and metal.8. Preparation of Specimens8.1 MetalChemically clean the specimens to removesurface contaminants, especially lubricants and fingerprintsfrom fabrica
23、tion and handling. Usually it is advisable topreoxidize parts as described in Annex A1. Preoxidationpromotes a better glass-to-metal bond and relieves cold-working stresses.NOTE 1The cleaned and heat-treated metal should be sealed within 24h and should be protected from surface contamination during
24、this period.8.2 GlassUsing optical-glass techniques grind and polishthe sealing surface of the glass specimens with either wetabrasive wheels or water slurries of abrasive on a lap. Thepolished surface should be at 90 6 2 to the specimen axis andwithout chips, nicks, or scratches. Remove any surface
25、 con-taminants which could produce bubbly seals. An ultrasonicwash may be used (Annex A1).8.3 Measure and record the dimensions (diameter, length,thickness) of each glass and each metal specimen.9. Procedure for Making the Butt-Seal9.1 Record dimensions of metal plates and glass parts.9.2 Make the s
26、eal in a furnace, by flame, or by inductionheating of the metal, utilizing suitable specimen holders orsupports under controlled conditions of temperature and time(Annex A2).FIG. 1 Rod SealsFIG. 2 Sheet SealsFIG. 3 Disk SealsF 140 98 (2008)210. Annealing10.1 Once a symmetrical, bubble-free seal has
27、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 materials from annealing temperature levels.This process involves heating the seal to a t
28、emperaturesomewhat higher than the annealing point of the glass andmaintaining the 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
29、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 and user mutuallydefine the annealing schedule and establish rigid controls for itsmai
30、ntenance.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 F 218.11.1.1 Position the cylindrical axis of the glass (in animmersion liquid, if needed) in a direction 45
31、from thedirection of vibration of the polarizer and analyzer, so that theline of sight or light path lies in the plane of the interface andpasses through its center.11.1.2 Determine the retardation along the light path interms of degrees of rotation of the analyzer. Rotate the analyzerin a direction
32、 that causes the curved black fringe seen withinthe glass to appear to move up to but not beyond theglass-metal interface (as though into the metal). Rotate theanalyzer so that any light or “gray” area which may existbetween the darkest part of the fringe (its center of width) andthe surface of the
33、metal disappears; this condition is termed“extinction.” When extinction is achieved correctly, the widthof the black fringe should appear to be about half its initialvalue, the other half apparently being obscured by the metal.Record the rotation of the analyzer required to produceextinction.NOTE 2S
34、ealing combinations may 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 3In certain glass
35、es, especially those compositions 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. The exact analysis of mismatch stre
36、ss should be evaluatedby completely removing the metal member by acid immersion. Theretardation should again be read at the same glass surface. Any residualretardation should then be algebraically subtracted from that previouslyobserved.NOTE 4If it is desired to minimize any uncertainties about meas
37、uringthrough the curved surfaces, these may be ground after annealing toconform to the alternate shapes of Fig. 1(b), 2(b), or 3(b). Opposing facesshould be ground so as to be parallel to each other and normal to the planeof the seal interface each within12 . For rod seals or sheet seals, grindingsh
38、ould be such that in Fig. 1(b) and 2(b) the dimension d is not less than0.8 dg. In the case of the alternative disk seal of Fig. 3(b), d must still beat least 5(tm+ tg). Grinding should be followed by reannealing beforemeasuring retardation. It should be borne in mind that grinding mayproduce micro
39、or macro cracks at the interface with the uncertaintiesassociated with these conditions.11.1.3 If an immersion liquid is used record the nominalindex of refraction, nD, of the liquid, and measure and recordto the nearest 0.1C the temperature of the liquid using animmersion mercury thermometer.11.1.4
40、 Record the type of light source and the effectivewavelength, L, in nanometres of the light for which theretardation has been measured. Record the interface extinctionangle and sense (tension or compression) as defined in TestMethod F 218.11.1.5 Measure the length d along the light path (Fig. 1,2,an
41、d 3) using a micrometer caliper with an index permittingdirect reading of 0.002 mm.12. Calculations12.1 Calculate the retardation per unit length of each speci-men as follows:R5LA/180d (1)where:R = retardation per unit length, nm/nm,L = wavelength of light source, nm,A = rotation of analyzer, deg, a
42、ndd = length of the light path through the interface, nm.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:S5R/K (2)where:S = stress parallel to interface, Pa,R =
43、average retardation per unit length of the test speci-mens, nm/nm, andK = stress-optical coefficient of the glass, Pa1.NOTE 5The stress-optical coefficient K of any reference glass shall besupplied by the manufacturer. Values for typical sealing glasses are foundin Table A1 of Specifications F 79 an
44、d F 105.12.4 Calculate the thermal expansion mismatch (or differ-ential thermal contraction of glass and metal between tempera-tures in the annealing range of the glass and room temperature)for the disk seals using the equation:5DL/L!T5S12!/EgF Note 6! (3)where:(DL/L)T= total expansion mismatch betw
45、een setting point of glass and roomtemperature, m/m, = Poissons ratio for glass,F = shape-modulus factor (kr4+3r2+4r)/(kr4+4r3+6r2+4r +1/k),k = Em/Eg,Em= Youngs modulus for metal, Pa,5Ondracek, M., “Magnitude and Distribution of Stresses in Test Seals Used inthe Photoelastic Study of Joints Between
46、Two Materials and in the Padmos Test”,Silikaty, SITKA, Vol 7, 1963, pp. 118. (In Czechoslovakian; English translationavailable from SLA Translation Center, 35 W. 33rd St., Chicago, IL 60616.)F 140 98 (2008)3Eg= Youngs modulus for glass, Pa,r = tm/tg,tm= thickness of metal, mm, andtg= thickness of gl
47、ass after sealing, mm.NOTE 6Use of this equation is valid only if d is a minimum of5(tm+ tg), the measurement is made at the glass-metal interface, and theunsealed faces of the glass and metal are parallel to the interface within 1.12.4.1 The shape-modulus factor, F, may be estimated fromFig. 4.13.
48、Report13.1 Report the following information:13.1.1 Type of metal and identification,13.1.2 Type of glass and identification,13.1.3 Diameter and length of glass for each specimen,13.1.4 Diameter and length (or length, breadth, and thick-ness) of metal rod (or sheet) for each specimen,13.1.5 Average o
49、xide thickness for specimens in a test lot interms of gain in weight per unit surface area after oxidation,13.1.6 Number of specimens tested,13.1.7 Annealing schedule,13.1.8 Length of the light path through glass at interface foreach specimen,13.1.9 Average and range of calculated retardation per unitlength,13.1.10 Stress-optical coefficient of glass,13.1.11 Type of light source and effective wavelength,13.1.12 Nominal index of refraction of immersion liquidand its temperature at the time of retardation measurements or,if no immersion liquid is used, th
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