Relationship between Nanomechanical Responses of Interfacial Intermetallic Compound Layers and Impact Reliability of Solder Joints

Bo-Chang Huang,Chih-Pin Hung,Jenn-Ming Song,David Tarng,Kiyokazu Yasuda

doi:10.3390/nano10081456

Abstract

This study aims to evaluate solder joint reliability under high speed impact tests using nanoindentation properties of intermetallic compounds (IMCs) at the joint interface. Sn–Ag based solder joints with different kinds of interfacial IMCs were obtained through the design of solder alloy/substrate material combinations. Nanoindentation was applied to investigate the mechanical properties of IMCs, including hardness, Young’s modulus, work hardening exponent, yield strength, and plastic ability. Experimental results suggest that nanoindentation responses of IMCs at joint interface definitely dominates joint impact performance. The greater the plastic ability the interfacial IMC exhibits, the superior impact energy the solder joints possess. The concept of mechanical and geometrical discontinuities was also proposed to explain brittle fracture of the solder joints with bi-layer interfacial IMCs subject to impact load.

Highlights

With portable devices developing rapidly towards multi-function and miniaturization, the reliability of the board-to-package joints has become more important
Since the device failure caused by solder joint damages usually arises from intermetallic compounds (IMCs) cracking when subjected to drop test, the mechanical features of IMCs significantly influence joint reliability
This study investigated impact properties of solder joints, nanomechanical behavior of IMCs at

Summary

Introduction

With portable devices developing rapidly towards multi-function and miniaturization, the reliability of the board-to-package joints has become more important. The joints between ball grid array (BGA). Packages and the printed circuit boards are usually assembled without the support of underfills. When the electronics fall to the ground, the board-to-package joints are subject to impact load and causes damages readily. In order to study the board-level solder joint reliability, a ball impact test (BIT) suffering high strain rate deformation was developed. Similar to a board-level drop test, BIT usually gives rise to brittle fracture at the interfacial IMCs [1,2]. Since the device failure caused by solder joint damages usually arises from IMCs cracking when subjected to drop test, the mechanical features of IMCs significantly influence joint reliability

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Conclusion