JEDEC JESD22-B115A 01-2016 Solder Ball Pull.pdf

1、JEDEC STANDARD Solder Ball Pull JESD22-B115A.01 (Revision of JESD22-B115A, August 2010) JULY 2016 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 subsequent

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9、mation, contact: JEDEC Solid State Technology Association 3103 North 10th Street Suite 240 South Arlington, VA 22201-2107 or call (703) 907-7559 JEDEC Standard No. 22-B115A.01 Page 1 Test Method B115A.01 (Revision of Test Method B115A) TEST METHOD B115A.01 SOLDER BALL PULL (From JEDEC Board Ballot J

10、CB-10-14 and JCB-16-17, formulated under the cognizance of the 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 pull

11、force/energy testing prior to end-use attachment. Solder balls are pulled individually using mechanical jaws; force, fracture energy and failure mode data are collected and analyzed. Other specialized solder ball pull methods using a heated thermode, gang pulling of multiple solder joints, etc., are

12、 outside the scope of this document. 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 solder joint integrity assessment methods such as JEDEC Solder Ba

13、ll Shear Test Method JESD22-B117, may be more appropriate. Generally, solder ball pull is most appropriate for devices that experience tensile loading during either the manufacturing/shipment process or end use, and have non-oblate (spherical, non-flattened) solder balls. This test method is used to

14、 assess the ability of solder balls to withstand mechanical pull forces that may be applied during device manufacturing, handling, test, shipment and end-use conditions. To provide a tensile load, this solder joint integrity assessment technique employs mechanical jaws to clamp an individual solder

15、ball of a free (unmounted) test sample. Solder ball pull is a destructive test. 2 Terms and definitions ball extrusion: Extreme deformation of a solder ball that may occur during an actual pull test due to factors such as insufficient jaw clamping pressure, incorrect jaw selection, etc. clamping fix

16、ture: A fixture that holds the test sample rigidly during solder ball pull testing (see Figure 2). elapsed time after reflow: The elapsed time between solder ball pull and last reflow of solder ball. failure mode: The type or location of failure observed after the solder ball is pulled. JEDEC Standa

17、rd No. 22-B115A.01 Page 2 Test Method B115A.01 (Revision of Test Method B115A) 2 Terms and definitions (contd) fracture energy: The total energy required to fracture the solder ball; typically calculated by integrating the force versus displacement during the solder ball pull process. jaw clamping p

18、ressure: The applied pressure exerted upon the solder ball by the pull tool. high-speed pull: Pull speed that is typically 50 1,000 mm/s, but can extend beyond this range. low-speed pull: Pull speed that is typically 0.1 15 mm/s. null drift calibration: The procedure whereby the load transducer outp

19、ut is periodically reset to a value of zero, separate from a transducer calibration. post-stress test: Solder ball pull evaluation performed after reliability stress testing such as temperature cycling or high temperature storage. pull force: The tensile loading action applied to a solder ball in a

20、direction perpendicular to the test sample planar surface. pull jaw: The tool that physically clamps the solder ball during the pull test (see Figure 2). pull speed: The nominal rate at which the pull tool moves in a direction perpendicular to the planar device surface as it pulls the solder ball. s

21、older pad opening diameter: The dimension defined by the base of a solder ball where the ball is bonded to a metallic surface. test instrument: An apparatus used to pull the solder ball from the test sample and measure the load applied to the solder ball (see Figure 1). JEDEC Standard No. 22-B115A.0

22、1 Page 3 Test Method B115A.01 (Revision of Test Method B115A) 3 General Ball Pull Apparatus A general solder ball pull apparatus is depicted in Figure 1. The test apparatus can be specifically designed for solder ball pull testing, or it may be possible to utilize a general mechanical load-deflectio

23、n test instrument. The apparatus must be capable of pulling solder balls at a known constant rate of displacement (test speed) and must be capable of recording generated tensile loads as a function of time through the use of a calibrated load cell or sensing element. Depending upon specific test sam

24、ple construction 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. Figure 1 General solder ball pull apparatus 4 Procedure 4.1 Solder Ball Compos

25、ition 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). Alternative failure mode assessment categories may be required for some solder ball configurations. Some solder ball materi

26、als may not be suitable for testing due to excess deformation or damage during the clamping and pulling operations, e.g., elastomer-core solder balls, etc Pull mechanism Test sample Test sample holder/clamp Manipulation stage to align balls to gripping jaws Solder ball gripping jaws Jaw actuatorLoad

27、 cell Signal analysis and data recording systemOperator interface JEDEC Standard No. 22-B115A.01 Page 4 Test Method B115A.01 (Revision of Test Method B115A) 4 Procedure (contd) 4.2 Base Material The test sample base material may be of organic or inorganic composition, and of any surface mount config

28、uration (BGA, CSP, etc.). Base material solder ball land pads may have a plated, deposited or coated surface finish. Silicon-based test samples may be more suitably evaluated using JEDEC Flip Chip Tensile Pull Test Method JESD22-B109, depending upon solder ball geometry, solder composition, etc. Som

29、e base materials may exhibit a predominant pad cratering failure mode, e.g., PTFE, polyimide-tape, etc.; for these cases IPC-9708, Pad Crater Test Method, may be a more appropriate test method. 4.3 Preconditioning The reflow temperature profiles associated with direct surface mount and rework proces

30、ses can affect solder ball pull 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 among comparative test samples. Test sample moisture loading prior to reflow is not

31、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 materials into already formed solder balls, such as Cu, to better replicate final

32、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 and ensure that the test sample planar surface is held perpendicular to the tool travel direction. Inadequate clamping may alter sold

33、er 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 pull testing that the clamping fixture is rigidly attached to the machine, and that any

34、 displacement or deformation is minimized to avoid resonant excitation of the test sample at the test speed. Regardless of pull speed, solder balls should not be tested over unsupported sections, e.g., exposed substrate region for typical overmolded BGA; custom fixturing may be required to provide s

35、upport across the entire test sample. In some cases, even custom fixturing may not be feasible to counter internal construction variations that may alter test results, such as a cavity in a lidded sample. To minimize eccentric loading on the force transducer assembly during high-speed testing, the c

36、lamping fixture should allow lateral movement of the sample, relative to the fixture, to position the tested solder ball over the lift table central axis. In addition, perpendicularity of the fixture and the tool travel direction is particularly critical for high-speed testing to reduce the potentia

37、l for lateral loading along the tool travel distance. JEDEC Standard No. 22-B115A.01 Page 5 Test Method B115A.01 (Revision of Test Method B115A) 4.4 Clamping Fixture (contd) An example of a clamping fixture is shown in Figure 2; however, the fixture may implement any of a variety of clamping means,

38、including customized fixtures that may accommodate multiple test sample sizes, as well as test samples in a strip or carrier format. Care should be taken to eliminate flexure of a package substrate or panel. The sample may need to be re-positioned in the clamping fixture to ensure that the test samp

39、le is well supported adjacent to the pull location; corner regions of the test sample may be particularly sensitive to edge clamp proximity. Typically, parallel, topside clamping bars should be applied on opposite sides of the tested solder ball. In cases where edge clamping schemes cannot adequatel

40、y prevent substrate flexure, rigid clamping schemes should be considered which may require bonding test samples to a rigid backing plate or suction through the use of a vacuum chuck. Figure 2 Example of a rigidly clamped test sample 4.5 Selection of the optimum pull jaw Insert the appropriate pull j

41、aw for the size of solder balls to be tested, and set the corresponding jaw clamping pressure/force. An appropriately selected pull jaw is one which will induce a minimum degree of ball deformation while clamping the solder ball and reforming it prior to the execution of a pull test. Typically, a ma

42、nufacturer of commercial ball pull testing equipment will provide a selection of pull jaws that are matched to specific solder ball diameters, and take into consideration the expected variations in solder ball and pad opening diameters. JEDEC Standard No. 22-B115A.01 Page 6 Test Method B115A.01 (Rev

43、ision of Test Method B115A) 4.5 Selection of the optimum pull jaw (contd) A suitable jaw may not always be possible depending on ball geometry and solder mask height/opening, as depicted in Figure 3. The ratio between the solder ball diameter and the solder pad opening diameter should be greater tha

44、n or equal to 1.1 and the ratio of the ball diameter to ball height should be less than 2.2. Dome shaped solder balls such as the solder ball depicted in the right hand side in Figure 3 are not suitable for ball pull testing. For purposes of ball pull testing, the optimum aspect ratio between solder

45、 ball diameter and solder pad opening diameter assures that the pull jaw will be allowed to properly reform the solder ball and apply a concentrated tensile load across a cylindrical column of solder above the interface between the solder ball and underlying metal surface finish. A jaw size should b

46、e selected that ensures that the resultant solder column diameter formed at the base of the solder ball upon jaw closure is 90% of the solder-wetted pad diameter; solder columns 2.2Solder pad opening diameter Solder pad opening diameter JEDEC Standard No. 22-B115A.01 Page 7 Test Method B115A.01 (Rev

47、ision of Test Method B115A) 4.6 Selection of the optimum pull jaw clamping pressure/force Pull jaw clamping pressure is typically adjustable on the solder ball pull apparatus and is monitored by a pressure indicator. Alternatively, clamping force may be monitored by strain gages integrated within th

48、e jaw actuation system and software-controlled. Some level of solder ball deformation due to clamping is expected given the ductile nature of most solder alloys; depending upon specific sample construction, the pull strength and failure mode may be significantly influenced by the solder clamping def

49、ormation. Once an appropriate pull jaw is selected, a suitable test sample size and test matrix should be established to evaluate the sensitivity of jaw clamping pressure/force. The test matrix should include a deliberately low clamping pressure/force, along with gradually incremented gripping pressures/forces until a transition from a ball extrusion to a primary failure mode (modes 1-4 in Table 4-1) can be observed. The optimal jaw clamping pressure/force is often solder ball alloy dependent. Other parameters such as pull speed and time duration (both before and during test) sh