Effect of Joint Size on Creep Behavior of Sn-Ag-Cu Solder-Cu Joints

Kanjilal, A and Narayanan, PR and Agilan, M and Kumar, P (2022) Effect of Joint Size on Creep Behavior of Sn-Ag-Cu Solder-Cu Joints. In: Journal of Electronic Materials .

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Abstract

This study investigates the effect of the joint length scale on the creep behavior of Pb-free Sn-rich Sn-3.0 wt. Ag-0.5 wt.Cu (SAC 305) solder-Cu joints. SAC 305-Cu solder joints having SAC solder layers of different thickness ranging from 1 mm to 50 μm were fabricated by diffusion bonding and examined using a scanning electron microscope to ascertain the role of length scale on the microstructure of the joints. Subsequently, tensile creep tests were performed at 85°C. At given nominal stress, a systematic reduction in the creep rate occurred with a reduction in joint thickness, which can be expressed by a power law. A comparison of the creep stress exponent of bulk SAC solder and the solder-Cu joints revealed that the creep mechanism was dislocation climb-controlled by core or pipe diffusion in both types of samples. The overall size-dependent creep strengthening of SAC 305-Cu joints can be attributed to the geometrical effects, which affect the macroscopic stress state, and the microstructural effect arising due to a change in the statistical distribution of Sn grains in the solder and the constraints on dislocation motion due to elastic Cu substrates. The additional strengthening imparted by precipitates in SAC solder was delineated by comparing the creep behavior of Sn-Cu joints with the SAC-Cu joints. © 2022, The Minerals, Metals & Materials Society.

Item Type:	Journal Article
Publication:	Journal of Electronic Materials
Publisher:	Springer
Additional Information:	The copyright for this article belongs to Springer.
Keywords:	Binary alloys; Copper; Copper alloys; Creep; Lead-free solders; Silver alloys; Ternary alloys; Tin alloys, reductions; Creep behaviors; Geometrical constraints; Length scale; Length scale effects; Micro-structural effects; Power law creep; SAC 305-cu joint; SAC-solders; SnAgCu solder, Scanning electron microscopy
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	09 Jan 2023 07:03
Last Modified:	09 Jan 2023 07:03
URI:	https://eprints.iisc.ac.in/id/eprint/78906

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