Deformation Behavior of Transient Liquid-Phase Sintered Cu-Solder-Resin Microstructure for Die-Attach

Abstract

We have proposed a low-temperature bonding technology utilizing the sintering of Cu particles with transient liquid-phase of Sn-based solder, called transient liquid-phase sintering (TLPS), as a die-attach solution for high-temperature power modules. A copper-intermetallic compound-resin (Cu-IMC-resin) microstructure, which consists of Cu particles connected with Cu–Sn intermetallic compounds (IMCs) partially filled with polyimide resin, is obtained by the pressureless TLPS process at 250 °C for 1 min using a novel Cu-solder-resin composite as the bonding material in a nitrogen atmosphere. Macro- and micro-deformation properties of the unique microstructure of the TLPS Cu-IMC-resin are evaluated by finite element analysis using a three-dimensional image reconstruction model. The macroscopic computational uniaxial tensile tests of the Cu-IMC-resin model reveal that the utilization of the IMCs and the addition of the easily-deformable resin facilitates the temperature-stability and low-stiffness of the mechanical properties. The microstructure exhibits a significantly low homogenized Young’s modulus (11 GPa). Microscopic investigations show that the local stresses are broadly distributed on the IMC regions under uniaxial macroscopic tensile displacement, indicating highly reliable performance of the joint within a specific macroscopic strain condition. Numerical and experimental investigations demonstrate the excellent thermal cyclic reliability of die-attached joints between silicon carbide chips and directly bonded copper substrate.

Recent Development of Joining and Conductive Materials for Electronic Components

“…Another problem with the TLP joint is that hard and brittle intermetallic compounds are formed at the joints, making it difficult to withstand excessive thermal strain. Consequently, die-attach materials for power modules using TLP-polyimide resin composites have been developed 118,119) to reduce the stiffness of the joints. The TLP joint structure, partially filled with polyimide resin, provides excellent thermal reliability.…”

Controlling Pore Position during Transient Liquid Phase Bonding for High-temperature Soldering Processes

“…As a result of advances in the development of highpower devices, as well as the integration, miniaturisation and high-power density applications in a variety of electronic devices, there has been an increase in demand for high-temperature interconnections, which have become a major concern in electronic packaging. [1][2][3][4] In recent decades, high-Pb solders have been preferred in high-temperature electronic applications for their cost-effectiveness and superior wettability. However, with the recognition of the harmfulness of lead (Pb) to the environment and health as stated by the Restrictions of Hazardous Substances (RoHS) directive, significant endeavours have been undertaken to substitute Pb-solders with eco-friendly materials and identify appropriate packaging techniques for high-temperature applications.…”