Insights into growth behavior of intermetallic compounds in Sn-Ag-Cu solder joints during mechanical and thermo-mechanical deformation processes

Kanjilal, A and Kumar, P (2020) Insights into growth behavior of intermetallic compounds in Sn-Ag-Cu solder joints during mechanical and thermo-mechanical deformation processes. In: 2019 IEEE 21st Electronics Packaging Technology Conference, EPTC 2019, 4-6 Dec. 2019, Marina Bay Sands Convention Centre, Singapore, pp. 48-52.

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Abstract

This work focuses on understanding the effect of strain rate imposed during various thermo-mechanical excursions (TMEs), such as thermal cycling and creep, and isothermal aging on the extent of coarsening of intermetallic compounds (IMCs) in diffusion bonded Sn-Ag-Cu(SAC)/Cu solder joints as well as reflowed bulk solder alloys. Fabricated samples were subjected to isothermal aging (IA), creep, thermal cycling (TC) and thermo-mechanical cycling (TMC) and the microstructure coarsening was monitored at regular intervals. A comparison has been made between thick joints of 1 mm thickness and micro-scale joints having a thickness of � 150 μm. Both the interfacial IMC layer and the Ag3Sn precipitates in the bulk are observed to undergo significant coarsening during each of the TMEs. While the 150 μm joint showed a faster growth in the IMC layer thickness as compared to 1 mm joint in the initial stages, a drastic reduction in the layer thickness was also observed in both the joints in the latter stages. Such a behavior is believed to happen due to the breaking of the IMC layer into the solder, a phenomenon which can severely impact the reliability of the joint. It is also observed that cyclic shear strain rates have the maximum severity on the microstructure coarsening kinetics for all joint sizes. Finally, a comprehensive understanding of the effect of all the TMEs on the coarsening behavior and joint reliability is proposed. © 2019 IEEE.

Item Type:	Conference Paper
Publication:	2019 IEEE 21st Electronics Packaging Technology Conference, EPTC 2019
Publisher:	Institute of Electrical and Electronics Engineers Inc. (IEEE)
Additional Information:	cited By 0; Conference of 21st IEEE Electronics Packaging Technology Conference, EPTC 2019 ; Conference Date: 4 December 2019 Through 6 December 2019; Conference Code:158393
Keywords:	Copper alloys; Creep; Electronics packaging; Intermetallics; Isotherms; Lead-free solders; Ostwald ripening; Shear strain; Silver alloys; Strain rate; Ternary alloys; Thermal conductivity; Thermal cycling; Tin alloys, Coarsening behavior; Cyclic shear strain; Isothermal aging; Joint reliability; Microstructure coarsening; Thermo-mechanical; Thermomechanical cycling; Thermomechanical deformations, Coarsening
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	19 Oct 2020 07:48
Last Modified:	19 Oct 2020 07:48
URI:	http://eprints.iisc.ac.in/id/eprint/65204

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