1、Designation: F 1269 06Standard Test Methods forDestructive Shear Testing of Ball Bonds1This standard is issued under the fixed designation F 1269; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover tests to determine the shearstrength of a series of ball bonds made by either thermalcompression or thermosonic tech
3、niques.NOTE 1Common usage at the present time considers the term “ballbond to include the enlarged spheriodal or nailhead portion of the wire,(produced by the flameoff and first bonding operation in the thermalcompression and thermosonic process, or both,) the underlying bondingpad, and the ball bon
4、d-bonding pad interfacial-attachment area or weldinterface.1.2 These test methods cover ball bonds made with smalldiameter (from 18 to 76-m (0.0007 to 0.003-in.) wire of thetype used in integrated circuits and hybrid microelectronicassemblies.1.3 These test methods can be used only when the ballheig
5、ht and diameter are large enough and adjacent interferingstructures are far enough away to allow suitable placement andclearance (above the bonding pad and between adjacent bonds)of the shear test ram.1.4 These test methods are destructive. They are appropriatefor use in process development or, with
6、 a proper sampling plan,for process control or quality assurance.1.5 Anondestructive procedure is possible;2although it maybe contra indicated due to the possible interference withadjacent wire bonds and microcircuit components.1.6 The values stated in SI units are to be regarded as thestandard. The
7、 values given in parentheses are for informationonly.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 o
8、f regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3F 458 Practice for Nondestructive Pull Testing of WireBondsF 459 Test Methods for Measuring Pull Strength of Micro-electronic Wire Bonds2.2 NIST Documents:4NBS Handbook 105-1 Specification and Tolerances forReference St
9、andards and Field Standards, Weights andMeasuresIOLM Class M2-Circular 547-1 Precision Laboratory Stan-dards of Mass and Laboratory Weights2.3 Military Standard:5MIL-STD 883C, Method 20103. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ball lifta separation of the ball bond at
10、the bondingpad interface with little or no residual (less than 25 % of thebond deformation area) ball metallization remaining on thebonding pad (that remains essentially intact). In the case ofgold ball bonds on aluminum pad metallization, a ball lift isdefined as a separation of the ball bond at th
11、e bonding padinterface with little or no intermetallic formation either presentor remaining (area of intermetallic less than 25 % of the bonddeformation area).3.1.1.1 Discussionntermetallic refers to the aluminumgold alloy formed at the ball bond pad metallization interfacialarea where a gold ball b
12、ond is attached to an aluminum padmetallization.3.1.2 ball shear (weld interface separation)an appre-ciable intermetallic (in the case of the aluminum-gold system)and ball metallization, or both, (in the case of the gold-to-gold1These test methods are under the jurisdiction of ASTM Committee F01 onE
13、lectronics and is the direct responsibility of Subcommittee F01.07 on WireBonding.Current edition approved Jan. 1, 2006. Published February 2006. Originallyapproved in 1989. Last previous edition approved in 2001 as F 126989(2001).2Panousis, N. T., and Fischer, M. W., “Nondestructive Shear Testing o
14、f BallBonds, International Journal of Hybrid Microelectronics, Vol 6, No. 1, 1983, p.142.3For 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 Summ
15、ary page onthe ASTM website.4Available from the National Technical Information Service, 5285 Port RoyalRd., Springfield, VA 22161.5Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr
16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.system) remains on the bonding pad (area of remaining metalor intermetallic greater than 25 % of the bond deformationarea).3.1.3 bonding pad lift (substrate metallization removal)aseparation between the bonding pad and the u
17、nderlying sub-strate. The interface between the ball bond and the residual padmetallization attached to the ball remains intact.3.1.4 crateringbonding pad lifts taking a portion of theunderlying substrate material with it. Residual pad and sub-strate material are attached to the ball. The interface
18、betweenthe ball and this residual material remains intact.3.1.4.1 DiscussionIt should be noted that cratering can becaused by several factors including the ball bonding operation,the post-bonding processing, and even the act of shear testingitself. If cratering occurs, chemically etch off the ball b
19、ondsand bond pads of untested units and microscopically check forcratering. Cratering caused prior to the shear test operation isunacceptable.Various aspects of the failure mode definitions are illustratedin Fig. 1.4. Summary of Test Methods4.1 The microelectronic device with the ball bond (wirebond
20、 (see Practice F 458 and Test Methods F 459) to be testedis held firmly in an appropriate fixture. A shearing ram ispositioned parallel to the substrate and approximately 25 m (1mil) above the substrate metallization. A typical shearingconfiguration is shown in Fig. 2. The ram is then moved intothe
21、ball until the ball separates from the substrate. The forceapplied to the ram, in order to cause the failure of the ball bond,is recorded. The mode of failure (for example, ball lift,weld-interface separation, cratering, etc.) is observed andrecorded.NOTE 2Bonds made with larger diameter wire may re
22、quire that theram be placed further above the substrate, but in all cases the ram shouldbe located below the balls horizontal centerline. The distance below thecenter should be at least half the distance between the center line and thesubstrate.NOTE 3Besides ball separation from the substrate, other
23、 modes offailure are possible and will be described in Section 6.5. Significance and Use5.1 Failure of microelectronic devices is often due to thefailure of an interconnection bond. A common type of inter-connection bond is the thermo compression or thermosonicgold wire bond. A very important elemen
24、t of this interconnec-tion is the first bond or ball bond. These test methods can assistin maintaining control of the process for making ball bonds.They can be used to distinguish between weak and nonadherentball bonds, of both, and bonds that are acceptably strong.5.2 These test methods are appropr
25、iate for on-line use inprocess control, for process development, for purchase speci-fications, and for research in support of improved yield andreliability. Since the ball shearing method tests only the firstbond in a microelectronic wire bond interconnection system, itmust be used in a complementar
26、y fashion6,7with the wire bondpull test.36. Inferences6.1 The most common interference is wire shear in whichthe ball is sheared too high or offline. Only a minor fragmentof the ball is attached to the wire. The major portion of the ballremains on the pad with the bond-pad weld interface regionintac
27、t. Wire shear is illustrated in Fig. 1, View B.6.2 Many of the common interference modes (such as wireshear) are caused by improper positioning of the ram during theball shear operation as shown in Fig. 3. Rams that are too high(Fig. 3, View B) or angled upward (Fig. 3, View D) result inlower than n
28、ormal shear strength values. Rams that are angleddownward (Fig. 3, View C and Fig. 4) or positioned too low(Fig. 3, View A) will strike the bonding pad and the substrate,or both, (chip) and cause inordinately high shear strength aswell as potentially damage the shearing ram.6.3 Shearing gold ball bo
29、nds on gold metallization pads orsubstrates can lead to friction rewelding as illustrated in Fig. 4.As a strongly welded gold bond is sheared, the ball tends to tipaway from the ram and contact the substrate as it moves. Theball smears against the pad metallization and rewelds itselfoften several ti
30、mes before it finally clears the metallization.6.4 In bonding systems in which excessive intermetallicgrowth has formed around the ball bond, the shearing ram maycontact the intermetallic rather than the ball bond and thus theshear readings can be in error (that is, weak ball bond shear ismasked by
31、the shear strength of the strong intermetallic wreathsurrounding it.6.5 When the bond pad pitch becomes too small to practi-cally shear test (which appears to be around#50 m pitch withcurrent equipment) then the only alternative is to use thedestructive bond pull test, Test Methods F 459, and accept
32、 thatresultant value, even if the ball lifts or pulls up the bond pad,assuming that value is acceptable by pull test criteria.7. Apparatus7.1 Ball Bond Shearing MachineApparatus for measuringthe ball bond shear strength are required with the followingcomponents:7.1.1 Shearing RamVarious shearing too
33、ls or rams havebeen recommended in the technical literature, but the ones thatappear the most effective have a flat chisel shape with ashearing edge dimension equal to approximately 1 to 2-balldiameters as shown in Fig. 5. For 25.4-m (1-mil) diameterwire this dimension would be approximately 0.152 m
34、m (6mils).6Charles, Jr., H. K., and Clatterbaugh, G. V., “Ball Bond ShearingAComplement to the Wire Bond Pull Test, International Journal of HybridMicroelectronics, Vol 6, No. 1, 1983, p. 171.7Harman, G. G. “The Microelectronic Ball-Bond Shear TestACritical Reviewand Comprehensive Guide to its Use,
35、International Journal of Hybrid Microelec-tronics, Vol 6, No. 1, 1983, p. 127.F 1269 0627.1.2 Shearing and Gaging MechanismMechanism forapplying a measured vertical (or horizontal) force to theshearing is needed. The mechanism shall incorporate a meansfor recording maximum force applied and shall be
36、 capable ofapplying the shear force at a uniform rate of ram motion. Forceapplication rate can be variable (either continuously or in fixedsteps) to accommodate different shearing conditions and con-figurations, or both. In no case should the ram speed exceed 6.0mm/s.NOTE 4It has been shown2that the
37、 shear force is independent of forceapplication rate in the range from 0.25 to 6.0 mm/s.FIG. 1 Ball Shear Failure ModesF 1269 063NOTE 5Electronic-strain gage-force reading mechanisms are pre-ferred; however, the dynamometer type mechanisms known as“ gramgages may be used satisfactorily providing car
38、eful calibration testprocedures are employed.7.1.2.1 The range of the force reading gage shall be selectedso that the maximum scale reading will be no greater than threetimes the expected average ball bond shear strength. Antici-pated force ranges for the various wire sizes and materialscovered by t
39、hese test methods are summarized7in Fig. 6.NOTE 6The maximum scale range of the electronic strain gage withdigital readout may be larger than three times the expected average shearstrength providing the accuracy specified in 10.7.6 is maintained over theentire range of the load cell.NOTE 1Schematic
40、diagrams of the ball shear test. (A) Horizontal sample and horizontal ram. (B) Horizontal sample and vertical ram.FIG. 2 Ball Shear Test ConfigurationsFIG. 3 Ball Shear InterferencesF 1269 0647.1.3 Microscope and Light SourceZoom microscopewith a light source for viewing the device under test is nee
41、ded.The minimum magnification shall be at least 603.7.1.4 Device Holder A clamping mechanism for rigidlyholding the device under test in either a horizontal or verticalposition depending upon shear tester configuration is required(see 7.2).7.1.5 Calibration MassesAt least five masses (weights)with m
42、ass values known to an accuracy of 0.5 % (or better,such as NBS Class T or IOLM Class M2 (NBS Handbook105-1 and Circular 547. IOLM)4) sized to cover the shearingand gaging mechanism range of force measurements andsuitably configured so that they may be supported by the shearmechanism for calibration
43、, are needed. In the case of horizontalshearing ram motion, the tester mechanism should rotate 90 toallow the weights to be hung from the shearing ram. Otherindirect methods of calibration may also be possible for thisconfiguration.7.1.6 Shear Test TolerancesThe shear test sample holderor the shear
44、test ram must be able to be positioned to tolerancesbetter than 610 m (6 0.4 mils) and the X and Y directions(plane of the bonding pad) and 5.0 m (60.2 mils) in the Z orthe above substrate direction. The shearing rams over travel(distance it proceeds from the point of ball contact) should belimited
45、to 2-ball diameters. Additional over travel may beallowed in cases where the excessive ram motion does notdamage other bonds or the device under test.7.2 Typical shear test configurations are illustrated in Fig. 7.View a shows a horizontal test system with horizontal shearingram motion. View b prese
46、nts a vertical test system with verticalshearing ram motion.8. Sampling8.1 Since the shear test method is destructive, it shall beperformed on a sampling basis. The sample selected should berepresentative of the ball bonds of interest. The size of thesample and the method of selection shall be agree
47、d upon by theparties to the test. The sample space should be as large aspractical (nominally 35 bonds) to ensure the proper statisticalinferences from quantities such as the mean shear force (X)and its standard deviation (s).9. Calibration9.1 Calibrate the ball bond shearing machine at the begin-nin
48、g and of each series of tests, or at the beginning and end ofeach day if the test sequence spans more than one day.9.2 For multifunction wire test machines, set up the testmachine in the proper configuration for the ball bond shear test,FIG. 4 Gold-to-Gold Friction ReweldingF 1269 065otherwise for a
49、 dedicated ball shear tester proceed with thecalibration steps in 9.3.9.3 Calibrate the shearing and gaging mechanism.9.3.1 For mechanisms or systems that incorporate a calibra-tion standard or mode, either calibrate the mechanism accord-ing to the manufacturers instructions or in accordance with theprocedure in 9.3.2.9.3.2 For mechanisms without a built-in calibration mode,select five masses (weights) that will provide at least fivecalibration points over the shear force range of interest. Attacha selected calibration mass to the shear
