1、Designation: F 205 94 (Reapproved 2005)Standard Test Method forMeasuring Diameter of Fine Wire by Weighing1This standard is issued under the fixed designation F 205; 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 measurement of the averagediameter of fine wire by weighing a known length; it appliesparticul
3、arly to sizes up to 0.13 mm (0.005 in.) used in electrondevices and lamps.1.2 The values stated in SI units are to be regarded as thestandard. The values given in inch-pound units apply only forthe diameter.1.3 This standard does not purport to address all of thesafety concerns, if any, associated w
4、ith its use. It is 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:2F 180 Test Method for Density of Fine Wire and Ribbon forElectron
5、ic Devices3. Apparatus3.1 The apparatus shall consist of a suitable torsion or otherdirect-reading balance capable of reading to 0.002 mg or 0.1 %of the weight to be weighed (whichever is larger), with anaccuracy of 0.004 mg or 0.2 % (whichever is larger). The rangeof the balance (or the size of the
6、 specimen) shall be such thatthe reading will lie within the upper half of the scale.4. Test Specimens4.1 Test specimens shall be selected at least 1 m from theend of a spool or sufficiently far from the end to be free fromkinks or other damage resulting in lack of straightness of thecut length.4.2
7、The wire shall be drawn from the spool under a loweven tension so that no elongation of the wire takes place.4.3 Each test specimen shall be cut to a length of 200 6 0.1mm. To prevent stretching, care shall be taken so that thetension is just sufficient to eliminate the sag and curl. Anydisagreement
8、 concerning the amount of tension to be used incutting shall be resolved between the manufacturer and thepurchaser.4.4 The test specimen shall be folded upon itself severaltimes and twisted to make a compact bundle with loopconsisting of a single strand for hanging it on the balancebeam. In the case
9、 of multiple specimens, all specimens shall betwisted together and hung by a loop consisting of a singlestrand. The specimen shall be handled as little as possible. Theoperators hands shall be clean and dry.5. Number of Specimens5.1 Weigh a single specimen if its weight lies within theupper half of
10、the scale of the instrument. When the weight isless than half of the scale of the instrument, weigh a sufficientnumber of specimens, 200 mm in length, simultaneously sothat the total weight will register in the upper half of the scale,preferably as close to the limit of the balance as possible. Uset
11、he lowest range instrument compatible with the weight of the200-mm weight specimen to reduce the number of 200-mmlengths that must be weighed together.6. Repetition of Weighing6.1 If the corrected weight of a single specimen lies within60.5 % of either the minimum or the maximum limit specifiedfor t
12、he wire weight, cut and weigh two more specimens of wirein a similar manner. When two or more lengths of wire havebeen weighed simultaneously to produce a reading in the upperhalf of the scale because of the small size of the wire, cut andweigh two more sets of specimens in a similar manner.7. Calib
13、ration and Checking of the Balance7.1 Check the balance regularly in accordance with therecommendations of the manufacturer.7.2 If a variety of weights are to be determined, calibrate thebalance at five major points on the scale and at zero bydetermining the weights of calibrated check weights. If a
14、nypoint is in error by more than 1 %, remove the balance from1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.03 on MetallicMaterials.Current edition approved Jan. 1, 2005. Published January 2005. Originallyapproved
15、in 1945 as B 205 45 T. Last previous edition approved in 1999 as F 205 94(1999).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
16、onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.service and repair it.Apply corrections determined by checkingto the apparent readings to obtain corrected weights. Obtaincorrections applied to apparent weights by i
17、nterpolation be-tween the closest calibrated points, one above and one belowthe reading.7.3 If the amount of work to be weighed at one point on thescale justifies it, the balance may be calibrated with a standardweight (or combination of weights) deviating by not more than10 % from that of the weigh
18、t to be determined. In this case,adjust the balance so that the balance reads the known weightof the check weight correctly when it is in balance, therebyreducing the correction to zero.7.4 Calibrate the balance, at zero under no load, or atpositive values when loaded to check weights, by using thea
19、verage of three consecutive readings, taken under conditionsspecified in 7.2 or 7.3, whichever is applicable.8. Calibration with Standard Weights8.1 Check weights are subject to change of mass due towear from handling and use, and from chemical action result-ing from exposure. Depending on use, but
20、not less than twicea year, compare the calibrated check weights with the primaryweights, calibrated by the National Institute of Standards andTechnology, and apply the necessary corrections.8.2 The primary standard check weights shall be NISTClass M, or equivalent, for weight determinations of 2.00
21、mgor less, and Class S, or equivalent, for weight determinationsover 2.00 mg.9. Procedure9.1 Handle and use the balance as recommended by themanufacturer. Direct particular attention to requirements forcareful handling, protection from vibration and atmosphericdust, errors induced by temperature cha
22、nges, and the necessityfor avoiding paralax in reading.10. Calculation10.1 Calculate the average diameter of the wire from thefollowing equation (see Appendix X1):D 5 3.1413/=D! 3 =W,where:D = average diameter of wire, mils (mils 3 0.0254 = mm),D = density of wire, g/cm3(see Note 1),W = weight of wi
23、re, mg/200 mm,Also, letK 5 3.1413/=D,thenD 5 K =W see Note 2!.NOTE 1The density of wire for alloys not found in Table 1 may bedetermined at or near the finished size and the finished condition inaccordance with Test Method F 180.NOTE 2Values for density and the constant K for several alloys aregiven
24、 in Table 1.11. Interpretation of Results11.1 If a single specimen or a single set of specimens isweighed, and its corrected weight, or average weight whenmultiple specimens are used, is found to lie between the point0.5 % above the minimum limit and 0.5 % below the maximumlimit, the wire shall be c
25、onsidered to meet the specified limits.11.2 If the corrected wire weight is under 0.5 % below theminimum limit or over 0.5 % above the maximum limit, thewire is considered not to meet the specified limits.11.3 If the corrected weight of a single specimen, or theaverage weight when multiple specimens
26、 are used, lies withinthe range of 6 0.5 % of the maximum or 60.5 % of theminimum limit, exactly three specimens or three sets ofspecimens shall be weighed, and the average corrected valuecompared with the maximum and minimum limits. If theaverage of the three readings lies between the maximum limit
27、and the minimum limit, the weight of the wire is considered tolie within these limits.NOTE 3The following is an example of the evaluation of results. If aspecified weight of 8.00 mg/200 mm and a specified tolerance of 63%(60.24, mg/200 mm) is assumed, the range determined by these specifi-cations mu
28、st be 7.76 to 8.24 mg/200 mm. The working zones for weighingwill be:Minimum limit:+ 0.5 %, 7.76 + 0.04 = 7.80 mg/200 mm0.5 %, 7.76 0.04 = 7.72 mg/200 mmMaximum limit:0.5 %, 8.24 0.04 = 8.20 mg/200 mm+ 0.5 %, 8.24 + 0.04 = 8.28 mg/200 mmThe corrected weight of a single cut length of wire found to lie
29、 between7.80 and 8.20 mg/200 mm will suffice to accept the wire. The correctedweight on a single cut length of wire found to be less than 7.72 mg/200mm or more than 8.28 mg/200 mm will suffice to reject the wire as outsidethe specified limits.If the corrected weight of a single cut length is found t
30、o be betweeneither 7.72 and 7.80 mg/200 mm, or 8.20 and 8.28 mg/200 mm, two morepieces shall be cut, weighed, and averaged with the first weight. If theaverage of the three weights lies between 7.76 and 8.24 mg/200 mm,inclusive, the wire is considered to meet the specified range; if outsidethese lim
31、its, it is considered not to meet it.12. Dimensions, Mass, and Permissible Variations12.1 Permissible variations from the specified weight shallbe designated by maximum and minimum weights, or as aplus-and-minus percentage tolerance to be applied to thenormal weight.TABLE 1 Density and Constant K fo
32、r Diameter CalculationsAlloyDensity,Ag/cm3ConstantKAluminum + 1 % magnesium 2.7 1.912Aluminum + 1 % silicon 2.7 1.912Gold 19.32 0.71585 % nickel, 15 % chromium 8.47 1.07958 % nickel, 20 % molybdenum, 20 %iron, 2 % manganese8.78 1.06095 % nickel, 5 % manganese 8.74 1.063Permanickel 8.77 1.061Monel 8.
33、81 1.058Molybdenum 10.14 0.986Tantalum 16.59 0.771Tungsten 19.17 0.717AThe density values in this table have been determined by ASTM Test MethodF 180.F 205 94 (2005)213. Report13.1 The report shall consist of the number of readings, andthe average corrected weight of the wire to three significantfig
34、ures in milligrams per 200 mm, except that for sizes under1.00 mg/200 mm only two significant figures shall be reported.The value reported shall be the weight of the outside end of thespool unless it shall have been agreed otherwise between themanufacturer and the purchaser.14. Precision and Bias14.
35、1 PrecisionThe precision of this test method has notbeen formally evaluated using an interlaboratory testing pro-gram. However, it is possible to evaluate the standard deviationof the wire diameter, s(D), for a given experimental setup,using the following equation which is based on propagation oferr
36、ors:sD! 5 =$dD /dD!2s2D! 5 dD /dW!2s2W! 1 dD/dL!2s2L!%.where each of the partial derivative terms are obtained fromappropriate differentiation of the definition of specimen wirediameter, D, shown in 10.1 and L is the wire length.14.2 BiasProper measurement technique for all the vari-ables shown in t
37、he equation which defines s(D)in14.1 shouldeliminate bias from this test method.15. Keywords15.1 electronic devices; fine wire; wire bondingAPPENDIX(Nonmandatory Information)X1. DERIVATION OF DIAMETER CALCULATION EQUATIONX1.1 The diameter calculation equation in Section 12 wasderived as follows:Wire
38、 weight 5 x2sectional area 3 length3 density, orW 5 p D2/4! 3 L 3D,where:W = wire weight,D = wire diameter,L = wire length, andD = wire density.Rearranging,D25 4W/p LDorD 5 = 4W/p LD51.1284 = W/LD.LetW 8 5 W/L,thenD 5 1.1284 =W 8/D.Correcting for unit:W 8 = weight in mg/200 mm (or mg/20 cm),D = dens
39、ity in gm/cm3(or 1000 mg/cm3), andD = diameter in mils (where 1 mil = 0.00254 cm),thenD 5 1.1284W 8 mg/20 cm!D1000 mg/cm3!/0.00254 cmmil,orD 5 1.1284 = W 8/D!cm2/20000! /0.00254 cm,orD 5 1.1284 cm/141.42! = W 8/D /0.00254 cm,orD 5 3.1413 =W 8/D.Other useful equations:W 8 5 0.10134 D D2, andD59.868 W
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43、mmittee on Standards, at the address shown below.This standard is copyrighted 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 205 94 (2005)3
