MECHANICAL PROPERTIES OF LEAD FREE SOLDER ALLOY FOR GREEN ELECTRONICS UNDER HIGH STRAIN RATE AND THERMAL AGING

  • Muhammad Amir Mechanical Engineering Department, CECOS University of IT & Emerging Sciences, Peshawar, Pakistan
Keywords: Lead free solder, Intermetallic compound particles, Thermal aging, Strain rate, Mechanical properties

Abstract

Lead free solder (LFS) alloys have been widely acknowledged due to its good mechanical properties and no
harmful effect on environment. The current work is focused on the examination of thermal aging and strain rates
on mechanical properties of Sn96.5-Ag3.0-Cu0.5 (SAC305) LFS alloy. The selected thermal aging temperatures are 60
°C, 100 °C and 140 °C. Strain rates are measured at 10/s, 20/s, 30/s and 40/s. The microstructure examination
before and after thermal aging is carried out using scanning electron microscopy (SEM) followed by confirmation
of chemical composition with energy dispersive X-ray (EDX). The microstructure is further analyzed using ImageJ
to investigate the Intermetallic compounds (IMCs) particle average size at different aging temperature. Mechanical
properties including Yield strength (YS) and Ultimate tensile strength (UTS) are examined before and after thermal
aging and at different high strain rates from stress-strain curves using universal testing machine (UTM). Results show
that LFS alloys are extremely sensitive to changes in both temperature and strain rate. The microstructure becomes
coarsen after thermal aging due to growth of average IMCs particle size which significantly results in reduction in
YS and UTS. Furthermore, increasing strain rates results in increasing YS and UTS due to less creep deformation.
Mathematical relations are also developed to predict these properties at various levels of aging temperature and strain
rate. A power law relationship exists between strain rate and mechanical properties while a reciprocal relationship
is obtained between aging temperature and mechanical properties.

References

1. Yasmin, T., Sadiq, M., and Khan, M., (2014),
“Effect of Lanthanum Doping on the Microstructure
Evolution and Intermetallic Compound (IMC)
Growth during Thermal Aging of SAC305 Solder
Alloy”, J Material Sci Eng.,Vol. 3(141), pp.
2169-0022.1000141.
2. Arulvanan, P., Zhong, Z., and Shi, X., (2006),
“Effects of process conditions on reliability, microstructure
evolution and failure modes of SnAgCu
solder joints”, Microelectronics Reliability, Vol.46(2),
pp. 432-439.
3. Sadiq, M., Pesci, R., and Cherkaoui, M., (2013),
“Impact of thermal aging on the microstructure evolution
and mechanical properties of lanthanum-doped
tin-silver-copper lead-free solders”, Journal of
Electronic Materials, Vol.42(3), pp. 492.
4. Schoenung, J.M., Ogunseitan, O.A., Saphores,
J.D.M., and Shapiro, A.A., (2004), “Adopting leadfree
electronics: policy differences and knowledge
gaps”, Journal of Industrial Ecology, Vol.8(4), pp.
59-85.
5. Yasmin, T. and Sadiq, M., (2014), “Impact Of
Lanthanum Doping on SAC305 Lead Free Solders
for High Temperature Applications”, Journal of
Engineering and Applied Sciences (JEAS), Vol.33(1)
pp. 29-36.
6. McCormack, M. and Jin, S., (1994), “Improved
mechanical properties in new, Pb-free solder alloys”,
Journal of Electronic Materials, Vol.23(8), pp.
715-720.
7. Reid, M., Punch, J., Collins, M., and Ryan, C.,
(2008), “Effect of Ag content on the microstructure
of Sn‐Ag‐Cu based solder alloys”, Soldering &
Surface Mount Technology, Vol.20(4), pp. 3-8.
8. Aamir, M., R Muhammad, MI Hanif, and
N Ahmed, (2016), “Relationships between
Microstructure and Mechanical Properties in High
Sn Content Pb-based and Pb-Free Solder Alloy after
Thermal Aging”, International journal of Advanced
Materials and Manufacturing, Vol.1(1), pp. 33-41.
9. Nakamura, Y., Sakakibara, Y., Watanabe, Y., and
Amamoto, Y., (1998), “Microstructure of solder joints
with electronic components in lead‐free solders”,
Soldering & Surface Mount Technology, Vol.10(1),
pp. 10-12.
10. Shnawah, D.A.A., Sabri, M.F.B.M., Badruddin,
I.A., and Said, S., (2012), “A review on effect of
minor alloying elements on thermal cycling and
drop impact reliability of low‐Ag Sn‐Ag‐Cu solder
joints”, Microelectronics International, Vol.29(1),
pp. 47-57.
11. An, T. and Qin, F., (2014), “Effects of the
intermetallic compound microstructure on the tensile
behavior of Sn3. 0Ag0. 5Cu/Cu solder joint under
various strain rates”, Microelectronics Reliability,
Vol.54(5), pp. 932-938.
12. Qin, F., An, T., and Chen, N., (2010), “Strain
rate effects and rate-dependent constitutive models
of lead-based and lead-free solders”, Journal of
Applied Mechanics, Vol.77(1), pp. 011008.
13. Plumbridge, W. and Gagg, C., (1999), “Effects
of strain rate and temperature on the stress–strain
response of solder alloys”, Journal of Materials
Science: Materials in Electronics, Vol.10(5), pp.
461-468.
14. Ali, B., (2015), “Advancement in microstructure
and mechanical properties of lanthanum-doped
tin-silver-copper lead free solders by optimizing
the lanthanum doping concentration”, Soldering &
Surface Mount Technology, Vol.27(2), pp. 69-75.
15. Wang, H., Liu, Y., Gao, H., and Gao, Z.,
(2014), “Effects of aging on microstructure evolution
and mechanical properties of high-temperature
Zn-4Al-3Mg solder”, Soldering & Surface Mount
Technology, Vol.26(4), pp. 203-213.
16. Aamir, M., Riaz Muhammad, Naseer Ahmed,
Khurshid Alam, (2015), “Impact of Thermal Aging
on Microstructure and Mechanical Properties of high
Sn Content, Sn-Pb Solders”, Fourth International
Conference on Aerospace Science & Engineering,
Islamabad, Pakistan, Institute of Space Technology.
17. Efzan Mhd Noor, E., Singh, A., and Tze Chuan,
Y., (2013), “A review: influence of nano particles
reinforced on solder alloy”, Soldering & Surface
Mount Technology, Vol.25(4), pp. 229-241.
18. Ervina Efzan, M. and Siti Norfarhani, I., (2015),
“Effect of Different Aging Times on Sn-Ag-Cu Solder
Alloy”, Transactions on Electrical and Electronic
Materials, Vol.16(3), pp. 112-116.
19. Tajik, S.J., Ahmad, M.M., Ahmad, I., and
Khan, J., (1998), “The effect of heat treatment on
microstructure and mechanical properties of steels”,
Journal of Engineering and Applied Sciences (JEAS),
Vol.17(2), pp. 113-116.
20. Rhee, H., Subramanian, K.N., Lee, A., and
Lee, J.G., (2003), “Mechanical characterization of
Sn‐3.5Ag solder joints at various temperatures”,
Soldering & Surface Mount Technology, Vol.15(3),
pp. 21-26.
21. Lall, P., Shantaram, S., Suhling, J., and Locker,
D., (2012), “Effect of high strain-rate on mechanical
properties of SAC105 and SAC305 leadfree alloys”,
Electronic Components and Technology Conference
(ECTC), 2012 IEEE 62nd, IEEE.
22. Hwang, J.S. and Vargas, R.M., (1990), “Solder
Joint Reliability—Can Solder Creep?” Soldering &
Surface Mount Technology, Vol.2(2), pp. 38-45.
Published
2017-11-20