JEDEC JESD22-B117B-2014 Solder Ball Shear.pdf

1、JEDEC STANDARD Solder Ball Shear JESD22-B117B (Revision of JESD22-B117A, October 2006) MAY 2014 JEDEC SOLID STATE TECHNOLOGY ASSOCIATION NOTICE JEDEC standards and publications contain material that has been prepared, reviewed, and approved through the JEDEC Board of Directors level and subsequently

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9、Suite 240 South Arlington, VA 22201-2107 or refer to www.jedec.org under Standards-Documents/Copyright Information. JEDEC Standard No. 22B117B Page 1 Test Method B117B (Revision of B117A) TEST METHOD B117B: SOLDER BALL SHEAR (From JEDEC Board Ballot, JCB-14-10, formulated under the cognizance of the

10、 JC-14.1 Subcommittee on Reliability Test Methods for Packaged Devices.) 1 Scope This document describes a test method only; acceptance criteria and qualification requirements are not defined. This test method applies to solder ball shear force/energy testing prior to end-use attachment. Solder ball

11、s are sheared individually; force, fracture energy and failure mode data are collected and analyzed. Both low- and high-speed testing are covered by this document. Depending on test sample configuration, application, and purpose of the test (characterization, qualification, production, etc.), other

12、solder joint integrity assessment methods such as JEDEC Solder Ball Pull Test Method JESD22-B115, may be more appropriate. Generally, solder ball shear is most appropriate for devices that experience shear loading during either the manufacturing/shipment process, or end use. This test method is used

13、 to assess the ability of solder balls to withstand mechanical shear forces that may be applied during device manufacturing, handling, test, shipment, and end-use conditions. Solder ball shear is a destructive test. This test method provides qualitative results and is suitable for process and materi

14、al characterization. 2 Terms and definitions base material: The substrate of the device where the solder balls are attached. clamping fixture: A fixture that holds the device rigidly during solder ball shear testing (see Figure 2). elapsed time after reflow: The elapsed time between solder ball shea

15、r and last reflow of solder ball. failure mode: The type or location of failure observed after the solder ball is sheared. fracture energy: The total energy required to fracture the solder ball. NOTE Typically fracture energy is calculated by integrating the force versus displacement during the sold

16、er-ball-shear process. high-speed shear: Shear occurring at a speed that produces a low-energy interfacial fracture of the solder ball; that speed is typically greater than 50 mm/s. JEDEC Standard No. 22B117B Page 2 Test Method B117B (Revision of B117A) 2 Terms and definitions (contd) low-speed shea

17、r: Shear occurring at a speed that is typically 0.1 mm 0.8 mm/s (100 m/s 800 m/s). null-drift calibration: The procedure whereby the load transducer output is periodically reset to a value of zero, separately from a transducer calibration. post-stress test: Solder ball shear evaluation performed aft

18、er reliability stress testing such as temperature cycling or high-temperature storage. shear force: The shear load applied to a solder ball in a direction parallel to the device planar surface. shear speed: The nominal rate at which the shear tool moves in a direction parallel to the device planar s

19、urface as it shears the solder ball. shear tool: A rigid tool that presses directly against the solder ball during shearing (see Figure 1). NOTE The shear tool is integrated with a sensing element so that shear force can be measured. shear tool standoff: The distance between the device planar surfac

20、e and the shear tool tip (see Figure 1). test apparatus: An instrument used to shear the solder ball from the test sample and measure the load applied to the solder ball. NOTE High-speed shear apparatus also measures the displacement. 3 Apparatus The test apparatus can be specifically designed for s

21、older ball shear testing, or it may be possible to utilize a general mechanical load-deflection test instrument. The apparatus must be capable of shearing solder balls at a known constant rate of displacement (test speed) and must be capable of recording generated shear loads as a function of distan

22、ce and time through the use of a calibrated load cell or sensing element. The shear tool alignment to the solder ball and standoff from the base material are shown in Figure 1. Separate equipment may be required to perform both low- and high-speed shear testing. Depending upon specific test sample c

23、onstruction and application, critical parameters associated with the test apparatus may vary from one test to another; Section 4 describes the various test parameters and the recommended reporting of these variables. JEDEC Standard No. 22B117B Page 3 Test Method B117B (Revision of B117A) 3 Apparatus

24、 (contd) Figure 1 Shear tool to solder ball alignment diagram (typical organic device) 4 Procedure 4.1 Solder Ball Composition This test method applies to any solder ball composition (SnPb, SnAgCu, etc.) or construction type (homogeneous solder alloy, solder-coated organic or metallic core, etc). Ho

25、wever, additional characterization work may be required for alternative solder ball configurations, assembly processes, and solder alloys. 4.2 Base Material The sample base material may be of organic or inorganic (ceramic, silicon, etc.) composition, and of any surface mount configuration (BGA, CSP,

26、 etc.). Base material solder ball land pads may have a plated, deposited or coated surface finish. Base materialShear speedShear tool standoffBall heightBall diameterShear toolDevice surfaceSolder ballJEDEC Standard No. 22B117B Page 4 Test Method B117B (Revision of B117A) 4.3 Preconditioning The ref

27、low temperature profiles associated with direct surface mount and rework processes can affect solder ball shear strength, failure mode and correlation to mechanical shock performance. Consequently, the reflow profile and total number of solder ball reflows should be recorded and kept consistent amon

28、g comparative test samples. Test sample moisture loading prior to reflow is not required. Test sample bake-out prior to reflow may be required if catastrophic damage at the solder ball attach region would otherwise occur due to the presence of moisture. Preconditioning may include the addition of ma

29、terials into already formed solder balls, such as Cu, to better replicate final solder ball composition of a device attached to a circuit board. 4.4 Clamping Fixture The clamping fixture must be designed to prevent the movement of the test sample in all axes and ensure that the test sample planar su

30、rface is held parallel to the tool travel direction. Inadequate clamping may alter solder joint failure mode as well as fracture strength. The clamping fixture should hold the sample securely without deforming the test sample or imparting any bow or twist. It is particularly critical for high-speed

31、shear testing that the clamping fixture is rigidly attached to the machine, and that any displacement or deformation is minimized to avoid resonant excitation of the test sample at the test speed. Laminate / module warpage can affect results; characterization of bottom surface coplanarity may need t

32、o be performed to ensure repeatable results. Some examples of clamping fixtures are shown in Figure 2; however, the fixture may implement any of a variety of clamping means, including vacuum hold down, adhering to a rigid carrier, and customized fixtures that may accommodate multiple test sample siz

33、es, as well as test samples in a strip or carrier format. The clamping fixture design can induce warpage of the test sample, and care should be taken to eliminate flexure of a package substrate or panel. No vertical movement of the test sample is desirable when the tool lands on the base material pr

34、ior to the tools step back to the standoff height. JEDEC Standard No. 22B117B Page 5 Test Method B117B (Revision of B117A) 4.4 Clamping Fixture (contd) Figure 2 Example clamping fixtures Side ViewWork holderClampsRigidly clamp sample into full contact with work holder. Thin samples may require clamp

35、ing close to test site.Front ViewLip machined in clamp to guide edge of package and prevent solder ball damage.Front ViewAlternative clamp method using sliding “vice” jawsJEDEC Standard No. 22B117B Page 6 Test Method B117B (Revision of B117A) 4.5 Sample Preparation Prior to test, solder balls shall

36、be visually examined to ensure that they are properly formed, free of residual flux or contaminants, and representative of the test lot. Note that the flux chemistry itself and any flux removal process may alter shear test results. Depending upon specific shear test apparatus constraints, solder bal

37、ls adjacent to the ball under test (and within the shear tool travel path) may first need to be removed using the shear tester, or manually through the use of a removal tool, such as a sharp blade, without damaging the ball to be sheared. If solder balls need to be removed, the residual solder heigh

38、t of the depopulated solder balls should be low enough to ensure that the shear tool does not contact this residual solder throughout the shear tool travel distance. A sufficient number of solder balls must remain after sample preparation to ensure that sample size and location requirements are stil

39、l met during actual shear testing. Figures 3 and 4 depict typical examples of sample preparation for low- and high-speed shear testing, respectively. Figure 3 Typical sample preparation for low-speed shear testing Figure 4 Typical sample preparation for high-speed shear testing Shear tool and shear

40、directionIf required, clear balls prior to testBalls that have been testedTest first row; then turn sample 90 to test second rowShear tool and shear directionBalls cleared prior to testBalls that have been testedJEDEC Standard No. 22B117B Page 7 Test Method B117B (Revision of B117A) 4.6 Shear Tool T

41、he shear tool should be constructed of hardened steel, ceramic or other non-yielding material. The shear tool should be about the width of the solder ball so it does not interfere with adjacent solder balls during the shear test. The shear tool shall be oriented 90 2 relative to the device planar su

42、rface. An alternative to the traditional chisel tool design is the cavity shear tool design, shown in Figure 5. On contact with the ball, the cavity tool rapidly distributes the shear load over a larger contact area, thereby reducing ball deformation, and increasing both the maximum load imparted at

43、 the bond interface and the possibility of bond failures instead of bulk solder shear. Figure 5 Cavity shear tool design Align the shear tool so that it will contact the side of the solder ball (see Figure 6). The cavity tool must be aligned to the ball centerline with higher precision (typically wi

44、thin 5 to 10% of the ball diameter) than the chisel tool, and there is a greater chance that solder will stick to the tool. The edge of the cavity tool should not cut into the solder ball. Figure 6 Cavity and chisel shear tool alignment to solder ball The shear tool standoff should be no greater tha

45、n 25% (10% preferred) of the solder ball height, and ensure that the shear tool does not contact the device surface throughout the monitored shear tool travel distance. Alignment of the shear tool with respect to a solder ball is best achieved with a moveable stage/tool-holder which permits movement

46、 in the plane perpendicular to the loading direction. Special care must be taken to ensure that the solder ball under test is not touched during the initial setup operation. JEDEC Standard No. 22B117B Page 8 Test Method B117B (Revision of B117A) 4.6 Shear Tool (contd) Wear of the shear tool tip (see

47、 Figure 7) due to extended use may affect test results. The shear tool shall be replaced if the tip shows signs of excessive wear that correlates to significantly altered shear force readings and/or failure modes. Wear features (nicks, gouges, rounding, etc.) observed under optical inspection to be

48、greater than approximately 1% of the tested solder ball height may require investigation of their impact on test results. Depending on the solder ball / pitch dimensions, larger allowances or thresholds may be more applicable. Residual solder on the shear tool should be removed using a small brush o

49、r similar implement, being careful not to damage the shear tool tip. Figure 7 Shear tool wear 4.7 Shear Speed The appropriate shear test speed should be determined based upon the test purpose and knowledge of the materials being tested. Depending upon the solder joint failure mode during device assembly and operation, either a low-speed (Condition A) or high-speed (Condition B) shear test may prove a more suitable solder joint integrity assessment method. Load the solder ball at a constant rate and record the shear speed. Record the shear force and fracture ene