Mechanical Characterization of Transient Liquid Phase Sintered (TLPS) Cu-Sn

Author(s):  
Erick Gutierrez ◽  
Subramani Manoharan ◽  
Maxim Serebreni ◽  
Patrick McCluskey

The increasing thermal demands in power electronic systems require the application of high temperature die attach materials. Transient Liquid Phase Sintered (TLPS) paste-based solder alloys have been demonstrated to effectively manage the thermal and mechanical load requirements of power modules. The microstructural features of these alloys provide interconnects with the necessary strength required to sustain high loads at high temperatures. To properly understand the influence of microstructure on mechanical behavior of these alloys, single lap shear experiments were performed on a TLPS system consisting of Copper and Tin particles (Cu-Sn). Nano-indentation measurements were performed on intermetallic phases of the TLPS, and the results obtained from lap shear testing and nano-indentation measurements are presented.

2021 ◽  
Vol 2021 (HiTEC) ◽  
pp. 000089-000093
Author(s):  
Gilad Nave ◽  
Patrick McCluskey

Abstract The need for power electronic devices and materials that can operate in harsh environments, together with the Restriction of Hazardous Substances (RoHS) legislation, has driven industry and researchers to develop new attach materials. Transient Liquid Phase Sintered (TLPS) joints are strong candidates to replace the current die attach materials due to their superior mechanical, thermal, and electrical properties. Despite these qualities, current TLPS systems may exhibit stiff and brittle behavior that can lead to die or attach fracture under large thermomechanical strains during wide temperature range cycling, or under mechanical stress from shock and vibration loading, such as is experienced in automotive electronics. This paper presents an approach for reducing thermal and mechanical strain levels by incorporating Transmission Electron Microscopy (TEM) Cu grids as a reinforcement to the attach material. The grids serve as ductile reinforcement capable of absorbing elastic and plastic energy, and as a barrier for crack propagations through the relative brittle TLPS material. Homogenization calculations were used to evaluate the effective properties of the TLPS, followed by numerical analysis that shows the effect of the grids on the die attach structure, and the mechanical integrity of the design.


2019 ◽  
Vol 9 (1) ◽  
pp. 157 ◽  
Author(s):  
Hiroaki Tatsumi ◽  
Adrian Lis ◽  
Hiroshi Yamaguchi ◽  
Tomoki Matsuda ◽  
Tomokazu Sano ◽  
...  

The evolution of the transient liquid-phase sintered (TLPS) Cu–Sn skeleton microstructure during thermal aging was evaluated to clarify the thermal reliability for die-attach applications. The Cu–Sn skeleton microstructure, which consists of Cu particles connected with Cu–Sn intermetallic compounds partially filled with polyimide resin, was obtained by the pressure-less TLP sintering process at 250 °C for 1 min using a novel Cu-solder-resin composite as a bonding material in a nitrogen atmosphere. Experimental results indicate that the TLPS joints were mainly composed of Cu, Cu6Sn5, and Cu3Sn in the as-bonded state, where submicron voids were observed at the interface between Cu3Sn and Cu particles. After thermal aging at 150, 175, and 200 °C for 1000 h, the Cu6Sn5 phase fully transformed into Cu3Sn except at the chip-side interface, where the number of the submicron voids appeared to increase. The averaged shear strengths were found to be 22.1 (reference), 22.8 (+3%), 24.0 (+9%), and 19.0 MPa (−14%) for the as-bonded state and specimens aged at 150, 175, and 200 °C for 1000 h, respectively. The TLPS joints maintained a shear strength over 19 MPa after thermal aging at 200 °C for 1000 h because of both the positive and negative impacts of the thermal aging, which include the transformation of Cu6Sn5 into Cu3Sn and the formation of submicron voids at the interface, respectively. These results indicate an excellent thermal reliability of the TLPS Cu–Sn skeleton microstructure.


2019 ◽  
Vol 9 (17) ◽  
pp. 3476 ◽  
Author(s):  
Hiroaki Tatsumi ◽  
Hiroshi Yamaguchi ◽  
Tomoki Matsuda ◽  
Tomokazu Sano ◽  
Yoshihiro Kashiba ◽  
...  

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.


2021 ◽  
Author(s):  
Kaustubh Bhatnagar ◽  
Subham Sahoo ◽  
Florin Iov ◽  
Frede Blaabjerg

Sign in / Sign up

Export Citation Format

Share Document