1、Designation: F 204 76 (Reapproved 2002)Standard Test Method forSurface Flaws in Tungsten Seal Rod and Wire1This standard is issued under the fixed designation F 204; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 test method covers the determination of the pres-ence of surface flaws in tungsten-seal rod and wire of randomor cut
3、lengths, and in the tungsten section of multiple-piece-through leads used in electronic devices, by means of exami-nation of a glass bead sealed to the tungsten.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the us
4、er of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 beaded lengththe actual length through which aglass-to-tungsten seal exists as evidenced by the color of theinterface.
5、2.1.2 faulta tungsten-glass seal in which a fissure, eitherdelineated by a line of bubbles or in itself clearly discernible,is observed when inspected as prescribed in this test method.2.1.3 fissureany narrow opening or cleft in the surface ofthe tungsten.2.1.4 line of bubblesone long or several sma
6、ll bubbles soarranged in the otherwise substantially bubble-free glass beadthat they are in an almost straight line immediately adjacent tothe tungsten-glass interface.3. Apparatus3.1 Beading EquipmentSuitable beading equipment ca-pable of producing glass-to-tungsten seals as prescribed inSection 4.
7、3.2 MicroscopeA low-power microscope capable of mag-nification up to 30 diameters, preferably of the binocular type.3.3 Light SourceA suitable white light source, preferablydiffuse for illumination of the bead under the microscope.4. Preparation of Test Specimen4.1 The test specimen shall be a beade
8、d tungsten rodprepared in the following manner:4.1.1 Clean the surface to be beaded in the usual manneremployed by the user of the tungsten.4.1.2 Alternative Methods of Specimen PreparationIncase of disagreement between the manufacturer and the pur-chaser, substitute one of the following alternative
9、 methods ofpreparing the tungsten rod for that in 4.1.1.4.1.2.1 Boil the tungsten for 2 min in a 5 % solution of 27 %hydrogen peroxide. Pour off the hydrogen peroxide and rinsethe tungsten twice in distilled water. Dry rapidly with purealcohol or in an oven heated to 100C.4.1.2.2 Place the tungsten
10、in a solution (20 weight %) ofsodium hydroxide or potassium hydroxide and pass sufficientelectrical current through it to induce electrolytic actionsufficient to clean the specimen.4.2 Bead the cleaned tungsten rod over the area to beexamined with glass, of the type and wall thickness commonlyused f
11、or beading, to a length of not less than 5 mm bead length.4.3 To permit examination of the glass-tungsten interface,the bead shall be substantially free from bubbles, from causesother than the tungsten defects, and shall have been so preparedthat the surface of the tungsten is clearly visible throug
12、h thebead.4.4 The color of the glass-to-tungsten seal shall be such asto indicate the proper application of heat to the bead to obtaina satisfactory seal.NOTE 1The usual preferred seal color shall be a golden-yellow hue.5. Procedure5.1 Hold the beaded tungsten in focus under the microscopein such a
13、manner that the beaded length may be observed.5.2 Rotate the specimen through 360 on its axis so that theentire surface of the tungsten-glass interface may be examined.5.3 Observe whether fissures or lines of bubbles are presentin the seal. If either are present, record the seal as a fault.6. Report
14、6.1 Report the following information:6.1.1 Purchase order number,6.1.2 Diameter of specimens,6.1.3 Number of specimens examined,6.1.4 Magnification used,6.1.5 Cleaning procedure used,6.1.6 Type and nominal wall thickness of glass bead used.1This test method is under the jurisdiction of ASTM Committe
15、e F01 onElectronics and is the direct responsibility of Subcommittee F01.03 on MetallicMaterials.Current edition approved Nov. 26, 1976. Published January 1977. Originallypublished as B 204 46 T. Last previous edition F 204 50 (1970). RedesignatedF 204 in 1955.1Copyright ASTM International, 100 Barr
16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.7 Nominal beaded length,6.1.8 Color of seal, and6.1.9 Number of faults observed.7. Keywords7.1 glass bead; glass-to-metal seals; tungsten-glass sealsASTM International takes no position respecting the validity of any pat
17、ent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision
18、 at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comm
19、ents will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighte
20、d by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F 2042
