Effects of Testing Conditions and Multiple Reflows on Cold Bump Pull Test of Pb-free Solder Balls

Abstract

Ball pull test has emerged to be an attractive alternative to the traditional ball shear testing method for characterizing the attachment strength of solder interconnection. Since this is a relatively new development, so far there is no industrial standard to regulate this testing method. In this study, the pull and shear tests are performed on plastic ball grid array (PBGA) solder balls with Sn-4.0Ag-0.5Cu and Sn-37Pb solders, subject to a wide variety of testing conditions. To investigate the material sensitivity of Sn-Ag-Cu and Sn-Pb solder balls, different pull speeds are used on both kinds of solder balls for comparison. The pull speed ranges from 25 µm/s to 5000 µm/s, while the shear speed ranges from 25 µm/s to 500 µm/s. The pull and shear tests are also conducted on samples with Sn-Ag-Cu and Sn-Pb solder balls after multiple reflows. Various failure modes of ball shear and ball pull tests are discussed for comparison. The sensitivity of both methods on brittle interface fracture is addressed. Furthermore, different pull speeds are applied to Pb-free solder samples after multireflows. Favorable testing conditions will be recommended.

Impact of IMC Thickness on Lead-free Solder Joint Reliability under Thermal Aging: Ball Shear Tests vs. Cold Bump Pull Tests

“…However, from previous research results [4], it seems that the ball shear test cannot correlate the degradation of ball shear strength to the growth of IMC thickness too well. This phenomenon should be due to the fact that IMCs are not that weak under the shear loading.…”

“…Firstly, the interface usually appears to be weaker in tension than in shear. Secondly, the failure in tensile as opposed to shear loading, is little influenced by solder mask interference and gross deformation of the solder [4,5].…”

“…The fractographs in Figs. 4 and 5 are given to illustrate the features of various failure. For ball pull tests after thermal aging, four types of failure modes were identified.…”

Assessment of solder pad cratering strength using cold pin pull test method with pre-fabricated pin arrays

“…In Table1, it shows the testing parameters and related materials. In the pin pull/ball pull test, both the testing condition and the thermal history of the testing samples were varied in order to get a comprehensive assessment on the testing method [9,10]. Since the NSMD pad opening was used, after the test, it was found that the pad crater was the only failure mode appeared in all the tests.…”

Impact of Low-k Devices on Failure Mode of Flip Chip Tensile Pull Test

“…Flip chip packaging use a variety of interconnection technology to connect the active side of silicon chip to multilayered substrate using a process called die attachment [1]. In order to determine solder bump joint strength, ball shear test [2], ball pull test [3] and stud pull or die pull test [4] were used.…”