Shear Toughness Evaluation of Solder Joints for the Reliability Tests
Chao-Ming Hsu
1,a, Ah-Der Lin
2,b, Tsung-Pin Hung
3,c, Wen-Chun Chiu
4,dand Jao-Hwa Kuang
3,e1
Department of Mechanical Engineering,National Kaohsiung University of Applied Science Kaohsiung, 80778, Taiwan
2
Department of Mechanical Engineering,Cheng-Shiu University, Kaohsiung, 83347, Taiwan 3
Department of Mechanical Engineering National Sun Yat-Sen University Kaohsiung, 80424, Taiwan
4
Orient Semiconductor Electronics, Ltd.,Kaohsiung, Taiwan, ROC a
jammy@cc.kuas.edu.tw, bahder@csu.edu.tw,cp923020009@student.nsysu.edu.tw, d
tonychiu@walton.com.tw, ekuang@mail.nsysu.edu.tw
Keywords: Ball shear test, shear energy, toughness, lead-free solder balls
Abstract. The effects of isothermal aging and the thermal cycling loading on the shear toughness of
different solder materials and ball sizes have been explored.The difference between shear toughness
values of traditional Sn/37Pb eutectic solder ball joints and the lead free Sn/3.0Ag/0.5Cu solders are chosen for discussion. The experiment measurements under the ball shear test (BST) have been compared and studied for both solder joints. The fracture behaviors of the solder joints under the high temperature aging and thermal cycling testing are examined by scanning electron microscope (SEM). The variation of shear toughness of different ball joints reveals that the high temperature aging and thermal cyclic loading reduce the shear toughness significantly. The measured shear toughness values indicate that the Sn/3.0Ag/0.5Cu solder joints have better ductility for the joints undergoing the high temperature aging and the thermal cycle loadings. Based on the measured results, the better reliability for the Sn/3.0Ag/0.5Cu ball joints is expected, due to the aging and cycling load testing.
Introduction
Accordingly, a number of Sn/Ag/Cu lead-free solders have been proposed for industrial application in recent years, including most notably Sn/3.4-4.1Ag/0.5-0.9Cu, Sn/3.9Ag/0.6Cu and Sn/3.0Ag/0.5Cu [1]. Lau et al [2] revealed brittle failure for Sn/Ag/Cu solder balls in terms of angle shear at high speed, and the details of load-displacement response and failure mode for these solder balls. Angle shear analysis showed the peeling and normal stress increased in a solder ball as the shear angle increased. Ikuo Shohji et al [3] have studied and investigated effect of specimen size and aging on tensile properties of Sn-Ag-Cu lead-free solders. In as-cast specimens, tensile strength increased with increasing Cu and Ag content. The tensile strengths are similar among eutectic and hypereutectic alloys after aging. Similar properties were noted in hypoeutectic alloys. This study uses the shear toughness of solder joints to investigate the joint failure mechanism for the isothermal aging and thermal cycling tests. The isothermal aging and thermal cycling tests are used for the reliability evaluation of solder joints. In this study, standard ball shear tests are performed by using specimens with ball diameters of 300, 600 and 760 µm, the shear force of the solder joints is applied to evaluate the shear energy, i.e. the area under the force-displacement curve obtained from the ball shear test. Experimental Setup
Treatment for the isothermal aging test Thirty-three modules of samples were analyzed in the test. The aging test was performed at 150℃. Storage times were 2 hrs, 4 hrs, 8 hrs, 16 hrs, 32 hrs, 48 hrs, 72 hrs, 144 hrs, 250 hrs, 500 hrs and 1000hrs.
Applied Mechanics and Materials Vol. 311 (2013) pp 467-471 Online available since 2013/Feb/27 at www.scientific.net
© (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.311.467
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 1.172.240.134, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan-31/03/13,19:45:06)
(a) Failure load (a) Sn/3.0Ag/Cu solder (b) Sn/37Pb solder Fig. 4 Interface photos of the solder joints for the
isothermal aging test
(b) Failure displacement (a) Sn/3.0Ag/Cu solder
(c) Shear toughness (b) Sn/37Pb solder
Fig.3 Results of ball shear test for the thermal Fig. 5 Interface photos of the solder joints for cycling tested solders of
φ
300µm the thermal cycling testReferences
[1] Edwin Bradley, Carol Handweker and John E. Sohn, Surf. Mt. Technol. (2003) 24-25.
[2] C. TC, Y. DQ, J. Lau, Z. WH, Z. XR, Elect. Components and Technol. Conf. (2008) 623-631. [3] Ikuo Shohji, Tsutomu Osawa, Takashige Matsuki, Yoshiharu Kariya, Kiyokazu Yasuda and
Tadashi Takemoto, “ Mater. Trans. Vol. 49 (2008) 1175-1179.
[4] C. M. Hsu, T. P. Hung, A. D. Lin and J. H. Kuang, Advanced Materials Research Vol.476-478 (2012) p.2455-2458 0 200 400 600 800 1000 0 1 2 3 4 5 F ai lu re L o ad F f ( N ) Number of Cycles Sn/3.0Ag/0.5Cu Sn/37Pb 0 200 400 600 800 1000 0 100 200 300 400 F ai lu re D is p la ce m en t X f ( µ m ) Number of Cycles Sn/3.0Ag/0.5Cu Sn/37Pb 0 200 400 600 800 1000 0 10 20 30 40 50 60 70 80 S h ea r T o u g h n es s E f ( m J) Number of Cycles Sn/3.0Ag/0.5Cu Sn/37Pb a b c d 0hr 48hr 500hr 1,000hr Cu Pad Cu Pad Cu Pad Cu Pad Ni Layer Ni Layer Ni Layer Ni Layer c d 0hr 48hr 500hr 1,000hr Cu pad Cu pad Cu pad Cu pad Ni layer Ni layer Ni layer Ni layer a b c d 0hr 48hr 500hr 1,000hr Cu Pad Cu Pad Cu Pad Cu Pad Ni Layer Ni Layer Ni Layer Ni Layer c d 0hr 48hr 500hr 1,000hr Cu pad Cu pad Cu pad Cu pad Ni layer Ni layer Ni layer Ni layer a b Crack c Crack d 0hr 48hr 500hr 1,000hr Cu Pad Cu Pad Crack Crack Crack
Ni layer Ni layer Ni layer
Ni layer Ni layer
Ni layer
As-reflowed Pre-con 250cy.
500cy. 750cy. 1,000cy.
As-reflowed Pre-con 250cy.
500cy. 750cy. 1,000cy.
Crack Crack Crack
Crack
Ni layer Ni layer Ni layer
Ni layer Ni layer
Ni layer
As-reflowed Pre-con 250cy.
500cy. 750cy. 1,000cy.
As-reflowed Pre-con 250cy.
500cy. 750cy. 1,000cy.
Crack
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Shear Toughness Evaluation of Solder Joints for the Reliability Tests
