1、Designation: F 459 06Standard Test Methods forMeasuring Pull Strength of Microelectronic Wire Bonds1This standard is issued under the fixed designation F 459; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods cover tests to determine the
3、pullstrength of a series of wire bonds. Instructions are provided tomodify the methods for use as a referee method. The methodscan be used for wire bonds made with wire having a diameterof from 0.0007 to 0.003 in. (18 to 76 m).NOTE 1Common usage at the present time considers the term “wirebond” to i
4、nclude the entire interconnection: both welds and the interven-ing wire span.1.2 These test methods can be used only when the loopheight of the wire bond is large enough to allow a suitable hookfor pulling (see Fig. 1) to be placed under the wire.1.3 The precision of these methods has been evaluated
5、 foraluminum ultra-sonic wedge bonds; however, these methodscan be used for aluminum ball bonds and gold wedge or ballbonds, as aluminum wedge bonds are the most sensitive tomanufacturing variations (such as bond deformation) of anywire-bond type.21.4 These methods are destructive. They are appropri
6、ate foruse in process development or, with a proper sampling plan, forprocess control or quality assurance.1.5 A nondestructive procedure is described in PracticeF 458.1.6 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only
7、.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with 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
8、Documents2.1 ASTM Standards:3F 458 Practice for Nondestructive Pull Testing of WireBonds3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 For the purposes of these test methods the followingfailure points are defined:3.1.2 bond-wire junction failurea rupture in the wirewithin tw
9、o wire diameters of the bond and in which more than25 % of the bonded area is left on the pad after the pull test hasbeen applied.3.1.3 weld interface failurea rupture in which less than25 % of the bonded area is left on the pad after the pull test hasbeen applied. See pad lifting in 6.6.3.1.4 wire
10、span failurea rupture in the wire other than (1)at a point within two wire diameters of either bond, or (2) at thepoint at which the hook contacted the wire.4. Summary of Test Methods4.1 The microelectronic device with the wire bond to betested is held firmly in an appropriate fixture. A hook isposi
11、tioned under the wire midway between the two bonds. Thehook is then raised until the wire bond breaks. The forceapplied to the hook in order to cause failure of the wire bondis recorded. The point of failure is observed and recorded. Inthe referee method, the force in the wire on breaking iscalculat
12、ed.5. Significance and Use5.1 Failure of microelectronic devices is often due to failureof an interconnection bond. A common type of interconnectionbond is a wire bond. These methods can assist in maintainingcontrol of the process of making wire bonds. They can be used1These test methods are under t
13、he jurisdiction of ASTM Committee F01 onElectronics and are the direct responsibility of Subcommittee F01.07 on WireBonding, Flip Chip, and Tape Automated Bonding.Current edition approved Jan. 1, 2006. Published February 2006. Originallyapproved in 1976 as F 459 76 T. Last previous edition approved
14、in 2001 asF 459 84(2001).2“Wire Bonding in Microelectronics, Materials, Processes, Reliability, andYield,” Second Edition, George Harman, McGraw Hill, 1997, pp. 6778.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
15、ook of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to distinguish between weak, nonadherent wire bonds andacceptably strong wire bo
16、nds. The methods are destructive.5.2 These test methods are appropriate for on-line use forprocess control, for purchase specifications, and for research insupport of improved yield or reliability. The referee methodshould be used for quantitative comparison of pull strengths ofwire bonds.6. Interfe
17、rences6.1 Failure to center the hook along the loop between thetwo bonds or pulling in a direction not lying in the planecontaining the undisturbed loop may invalidate the test since anunbalanced distribution of forces between the two bonds mayresult.6.2 Slippage of the hook along the wire span duri
18、ng pullingmay invalidate the test because an unbalanced distribution offorces between the two bonds may result.6.3 Careless insertion of the hook may damage either bondor wire and thus invalidate the test.6.4 The presence of vibration or mechanical shock maycause the application of an extraneous for
19、ce and thus invalidatethe test.6.5 Measured bond-pull force is strongly dependent on theheight of the loop (H+h, as defined in 11.1.1) and thebond-to-bond spacing (d, as defined in 11.1.1).6.6 For fine pitch ball bonds (60 m pitch), the bond padmay tear and lift during pull testing. Current practice
20、 is toaccept this if the pull force is acceptably high under agreedupon requirements, but note it as appropriate. In some cases ofbad peeling, it is necessary to move the pulling hook directlyover the top of the ball bond. This should be noted.7. Apparatus7.1 Bond-Pulling MachineApparatus for measur
21、ing wire-bond pull strength with the following components:7.1.1 HookPulling hook made from rigid wire such astungsten. The diameter of that part of the hook that contacts thewire loop should be approximately 2.5 times the diameter ofthe wire used to make the wire bond. A suggested hookconfiguration
22、is shown in Fig. 1. The hook should appear undervisual inspection to have a smooth polished surface with nosharp edges in any part of the hook that contacts the wire loop.The hook should be rigidly mounted in the pulling apparatus.7.1.2 Lifting-and-Gaging MechanismMechanism for ap-plying a measured
23、vertical force to the hook. The mechanismshall incorporate a means for recording the maximum forceapplied and shall be capable of applying force at a rate constantto within 2 gf/s (20 mN/s) in the range from 1 to 30 gf/s (10 to290 mN/s) inclusive. A mechanism with a single fixed scaleshall have a ma
24、ximum scale reading no greater than three timesthe nominal bond pull strength anticipated.NOTE 2Mechanisms of the dynamometer type known as “gramgages” have been found satisfactory.7.1.3 Microscope with Light SourceZoom microscopewith light source with a magnification range of approximately143 to 60
25、3 with the eyepiece not to exceed 103, for viewingthe device under test.7.1.4 Device HolderMechanism for holding the deviceunder test (1) in a horizontal position, for Method A, or (2) ineither a horizontal or a tipped position so that both bonds arein the same horizontal plane, for Method B. For th
26、e refereeMethod C, the device holder should provide a measurement, towithin 2, of the angle from the horizontal (which may be zero)through which the device has been tipped.7.1.5 Calibration MassesAt least five masses (weights)with mass values known to within 0.5 % sized to cover thelifting-and-gagin
27、g mechanism range of force measurement,and suitably configured so that they may be supported by thepulling mechanism for calibration.8. Sampling8.1 Since the pull-test method is destructive, it shall beperformed on a sampling basis. The sample selected should berepresentative of the wire bonds of in
28、terest. The size of thesample and the method of selection shall be agreed upon by theparties to the test.9. Calibration9.1 Calibrate the bond-pulling machine at the beginning ofeach series of tests, or daily if a series spans more than one day.9.2 Assemble the bond-pulling machine in the same con-fi
29、guration to be used to perform the wire-bond pull test.9.3 Calibrate the lifting-and-gaging mechanism.9.3.1 For mechanisms incorporating a calibration adjust-ment, either calibrate the mechanism in accordance with themanufacturers instructions or in accordance with the proce-dure of 9.3.2.9.3.2 For
30、mechanisms without a calibration adjustment, usethe following procedure:FIG. 1 Suggested Configuration for a Pulling HookF4590629.3.2.1 Select masses that will provide at least five calibra-tion points over the mechanism range.9.3.2.2 Attach a selected calibration mass to the lifting-and-gaging mech
31、anism. If a lever-arm mechanism (dynamometeror gram gage) is used, rotate the body of the gage in a mannerthat maintains the arm (carrying the hook) in a horizontalorientation.9.3.2.3 Observe and record the measured force in grams-force (millinewtons).9.3.2.4 Repeat 9.3.2.2 and 9.3.2.3 for each cali
32、bration massselected.9.3.2.5 Plot the measured force values as a function of theforces applied by the masses. Use these results to construct acalibration curve.10. Procedures10.1 Method ADevice in Horizontal Plane:10.1.1 Place the device having the wire bond to be tested inthe device holder so that
33、the plane of the device is horizontal,as judged visually.10.1.2 Position the microscope and light source and focusthe microscope so that the wire bond to be tested is clearly seenin the microscope field.10.1.3 Position the device holder so that the wire formingthe loop of the wire bond to be tested
34、is under the rigidlymounted pulling hook.10.1.4 While viewing the wire bond through the micro-scope, maneuver the hook so that it is under the wire loop to bepulled, and adjust the hook so that it is midway between thetwo bonds and contacting the wire loop, as judged by eye.10.1.5 Activate the pulli
35、ng mechanism while observing thewire bond and hook through the microscope. Continue pullinguntil there is failure.10.1.6 If the wire fails at the point of contact with the hook,record the test for that bond as invalid.10.1.7 Measure and record the force required for breakingthe wire bond. Determine
36、and record the corrected force fromthe calibration curve if the calibration procedure of 9.3.2 wasused. Record the identification of the wire bond and theidentification of the device (substrate).10.1.8 Examine the remaining parts of the bonds and thewire span at appropriate magnification to determin
37、e the natureand location of the failure.10.1.9 Record the failure location as being one of thefollowing:10.1.9.1 First bond at the weld interface,10.1.9.2 First bond at the bond-wire junction,10.1.9.3 In the wire span,10.1.9.4 Second bond at the weld interface,10.1.9.5 Second bond at the bond-wire j
38、unction, or10.1.9.6 Other (describe: for example, pad lift-off (see 6.6).NOTE 3The operator will normally be supplied information as towhich is the first bond and which is the second bond.10.2 Method BDevice in Tipped Plane:10.2.1 Place the device having the wire bond to be tested ina device holder
39、capable of tipping.10.2.2 Perform steps 10.1.2 and 10.1.3.10.2.3 Tip the holder (if required) until both bonds appear tobe in sharp focus as viewed through the microscope.NOTE 4Care should be taken not to tip the wire bond about thebond-line axis. However, a judgment by eye through the microscope is
40、adequate, as an error of a few degrees will not significantly alter themeasured pull strength.10.2.4 Perform steps 10.1.4-10.1.9.10.3 Method CReferee Method:10.3.1 Measure and record the horizontal distance (d) be-tween the two bonds, the vertical distance (H) between the twobonds, and the loop heig
41、ht (h) as shown in Fig. 2. Use the sameunit of measurement for d, h, and H.10.3.2 Use either Method A or Method B, whichever isappropriate.10.3.3 If Method B is used, read and record the tip angle(the angle through which the device has been tipped from thehorizontal) to within 2.11. Calculation (for
42、 Method C)11.1 If the substrate was tipped from the horizontal, calcu-late the force in grams-force (or millinewtons) in the wire atfailure.11.1.1 If failure occurs at the higher of the two bond sites,calculate the force in the wire as follows:2Fhi5 F1 1Sd2hD2S1 1H2hDF12cos f1Sh 1 HdDsin fGFIG. 2 Di
43、agram of a Typical Wire BondF459063where:Fhi= force in the wire on the high side, gf (or mN),F = corrected applied pull force, gf (or mN),d = horizontal distance between the two bonds along aparallel to plane of device,H = vertical distance between the two bond sites along aperpendicular to plane of
44、 device,h = loop height as defined in Fig. 2, andf = angle through which device has been tipped.11.1.2 If failure occurs at the lower bond site, calculate theforce in the wire as follows:Flo5S1 1HhDS1 1H2hD1 1Fd2 H 1 h!G2F12cos f2hdsin fGwhere Flo= force in the wire at the low side in grams-force(or
45、 millinewtons) and the other symbols are as indicated in11.1.1.11.2 If the device was not tipped from the horizontal,calculate Fhiand Floas follows:Fhi5 F1 1Sd2hD2S2 1HhDFlo5 FS1 1HhDS2 1HhD1 1Fd2H 1 h!G2where the symbols have the same meaning as in 11.1.1 and11.1.2.12. Report12.1 Method AThe report
46、 for Method A shall contain thefollowing:12.1.1 Name of the person performing the test,12.1.2 Date of the test,12.1.3 Identification of the wire-bond pull tester,12.1.4 Identification of the device,12.1.5 Identification of each wire bond,12.1.6 Corrected force in grams-force (or millinewtons)require
47、d to break the wire bond, and12.1.7 Location of failure.12.2 Method BIn addition to that required by 12.1, thereport for Method B shall contain the angle through which thedevice was tipped.12.3 Method CIn addition to that required by 12.1, thereport for Method C shall contain the following:12.3.1 Me
48、asured values of d, H, and h, in the same units,12.3.2 Angle through which device was tipped, if Method Bwas used, and12.3.3 Calculated force in the wire in grams-force (ormillinewtons).13. Precision and Bias13.1 An interlaboratory evaluation of these test methodswas carried out as follows:13.1.1 Si
49、x laboratories participated, including the originat-ing laboratory.13.1.2 Aluminum ultrasonic wedge bonds were used em-ploying Al-1 % Si wire 0.001-in. (25.4-m) diameter.13.1.3 Each test specimen prepared by the originatinglaboratory contained groups of bonds with three different meanpull strengths: high-quality bonds, approximately 10 gf (98mN); average-quality bonds, approximately 7.5 gf (74 mN);and low-quality (overly deformed) bonds, approximately 4.0 gf(39 mN).13.2 The wire-bond pull test is destructive, and different testsamples do not necessa
