1、Designation: F1269 13 (Reapproved 2018)Standard Test Methods forDestructive Shear Testing of Ball Bonds1This standard is issued under the fixed designation F1269; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 These test methods cover tests to determine the shearstrength of a series of ball bonds made by either thermosonicor thermal c
3、ompression techniques using either gold or copperwires.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/spark EFO and first bonding operation in thethermosonic or thermal compression proce
4、ss), and the ball bond-bonding pad interfacial-attachment area or weld interface.1.2 These test methods cover ball bonds made with smalldiameter (from 18 to 76-m (0.0007 to 0.003-in.) gold orcopper wire of the type used in integrated circuits and hybridmicroelectronic assemblies, system on a chip, a
5、nd so forth.1.3 These test methods can be used only when the ballheight 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 des
6、tructive. They are appropriatefor use in process development or, with a proper sampling plan,for process control or quality assurance.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to add
7、ress all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was deve
8、loped in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Doc
9、uments2.1 ASTM Standards:2F458 Practice for Nondestructive Pull Testing of Wire BondsF459 Test Methods for Measuring Pull Strength of Micro-electronic Wire Bonds2.2 NIST Documents:3NBS Handbook 105-1 Specification and Tolerances for Ref-erence Standards and Field Standards, Weights and Mea-suresIOLM
10、 Class M2-Circular 547-1 Precision Laboratory Stan-dards of Mass and Laboratory Weights2.3 Military Standard:4MIL-STD 883, Method 20103. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ball lifta separation of the ball bond at the bondingpad interface with little or no residual (
11、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 the bonding padinterface with little or no intermetalli
12、c formation either presentor remaining (area of intermetallic less than 25 % of the bonddeformation area).3.1.1.1 DiscussionIntermetallic refers to the aluminumgold alloy formed at the ball bond pad metallization interfacialarea where a gold ball bond is attached to an aluminum padmetallization. If
13、the wire/ball is of copper, then the aluminumintermetallic is normally much thinner and may not be opti-cally observable.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-go
14、ld1These test methods are under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.03 on MetallicMaterials, Wire Bonding, and Flip Chip.Current edition approved March 1, 2018. Published April 2018. Originallyapproved in 1989. Last previous editi
15、on approved in 2013 as F126913. DOI:10.1520/F1269-13R18.2For 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.3Avai
16、lable from the National Technical Information Service, 5285 Port RoyalRd., Springfield, VA 22161.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
17、onshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade
18、 Organization Technical Barriers to Trade (TBT) Committee.1system) 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 underlying sub-str
19、ate. 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 betweenthe ball a
20、nd 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 bondsand bond pads
21、 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 (see Practice F4
22、58 and Test Methods F459) 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 (except for the case offine pitch bond bonds and pads, where the ram height can belower, depending on
23、the pitch, final ball height,5and so forth.A typical shearing configuration is shown in Fig. 2. The ram isthen moved into the ball until the ball separates from thesubstrate. The force applied to the ram, in order to cause thefailure of the ball bond, is recorded. The mode of failure (forexample, ba
24、ll lift, weld-interface separation, cratering, etc.) isobserved and recorded.NOTE 2Bonds made with larger or smaller diameter wire may requirethat the ram be placed further above the substrate, or lower, but in all casesthe ram should be located below the balls horizontal centerline. Thedistance bel
25、ow the center should be at least half the distance between thecenter line and the substrate.NOTE 3Besides ball separation from the substrate, other 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
26、 of an interconnection bond. The most common type ofinterconnection bond is the thermosonic gold or copper wirebond. A very important element of this interconnection is thefirst bond or ball bond. These test methods can assist inmaintaining control of the process for making ball bonds. Theycan be us
27、ed to distinguish between weak and nonadherent ballbonds, of both, and bonds that are acceptably strong.5.2 These test methods are appropriate for on-line use inprocess control, for process development, for purchasespecifications, and for research in support of improved yieldand reliability. Since t
28、he ball shearing method tests only thefirst bond in a microelectronic wire bond interconnectionsystem, it must be used in a complementary fashion5,6with thewire bond pull test.36. Inferences6.1 The most common interference is wire shear in whichthe ball is sheared too high or offline. Only a minor f
29、ragmentof the ball is attached to the wire. The major portion of the ballremains on the pad with the bond-pad weld interface regionintact. 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 th
30、eball 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 normal 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 subs
31、trate,or both, (chip) and cause inordinately high shear strength aswell as potentially damage the shearing ram.6.3 Shearing gold ball bonds 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 tip
32、away from the ram and contact the substrate as it moves. Theball smears against the pad metallization and rewelds itselfoften several times before it finally clears the metallization.6.4 In bonding systems in which excessive intermetallicgrowth has formed around the ball bond, the shearing ram mayco
33、ntact the intermetallic rather than the ball bond and thus theshear readings can be in error (that is, weak ball bond shear ismasked by 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 ar
34、ound 30 m pitch withcurrent equipment) then the only alternative is to use thedestructive bond pull test, Test Methods F459, and accept 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 Mach
35、ineApparatus for measuringthe ball bond shear strength are required with the followingcomponents:7.1.1 Shearing RamVarious shearing tools 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
36、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 mm (6mils).5Charles, Jr., H. K. and Clatterbaugh, G. V., “Ball Bond ShearingA Comple-ment to the Wire Bond Pull Test,” International Journal of Hybrid Microelectronic
37、s,Vol 6, No. 1, 1983, p. 171.6Harman, G. G. “The Microelectronic Ball-Bond Shear TestACritical Reviewand Comprehensive Guide to its Use, International Journal of HybridMicroelectronics, Vol 6, No. 1, 1983, p. 127; also Harman, G. G., Wire Bonding inMicroelectronics, Third Edition, McGraw Hill, 2010,
38、 pp. 110-118.F1269 13 (2018)27.1.2 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 capable ofapplying the shear force at a uniform rate of ra
39、m motion. Forceapplication rate can be variable (either continuously or in fixedsteps) to accommodate different shearing conditions andconfigurations, or both. In no case should the ram speed exceed6.0 mm/s.NOTE 4It has been shown that the shear force is independent of forceapplication rate in the r
40、ange from 0.25 to 6.0 mm/s.NOTE 5Electronic-strain gage-force reading mechanisms are theindustry standard; however, the dynamometer type mechanisms knownas“ gram gages may be used satisfactorily providing careful calibrationtest procedures are employed.7.1.2.1 The range of the force reading gage/sen
41、sor shall beselected so that the maximum scale reading will be no greaterthan three times the expected average ball bond shear strength.FIG. 1 Ball Shear Failure ModesF1269 13 (2018)3Anticipated force ranges for the various wire sizes and mate-rials covered by these test methods are summarized6in Fi
42、g. 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.7.1.3 Microscope and Light SourceZoom microscopewith a
43、 light source for viewing the device under test is needed.The minimum magnification shall be at least 60.7.1.4 Device HolderA 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 Ca
44、libration MassesAt least five masses (weights)with mass 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)3) sized to cover the shearingand gaging mechanism range of force measurements andNOTE 1Schematic diagrams of the bal
45、l shear test. (A) Horizontal sample and horizontal ram. (B) Horizontal sample and vertical ram.FIG. 2 Ball Shear Test ConfigurationsFIG. 3 Ball Shear InterferencesF1269 13 (2018)4suitably configured so that they may be supported by the shearmechanism for calibration, are needed. In the case of horiz
46、ontalshearing 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 test ram must be able to be positi
47、oned 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 to 2-ball diameters. Additional ov
48、er 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 presents a vertical test system with ve
49、rticalshearing 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 agreed 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 ().9. Calibration9.1 Calibrate the ball bond shearin
