Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XXII: Interconnection Materials
Sponsored by: TMS Functional Materials Division, TMS: Alloy Phases Committee
Program Organizers: Hiroshi Nishikawa, Osaka University; Shih-kang Lin, National Cheng Kung University; Chao-hong Wang, National Chung Chung University; Chih-Ming Chen, National Chung Hsing University; Jae-Ho Lee, Hongik University; Zhi-Quan Liu, Shenzhen Institutes of Advanced Technology; Ming-Tzer Lin, National Chung Hsing University; Yee-wen Yen, National Taiwan University of Science and Technology; A.S.Md Abdul Haseeb, Bangladesh University of Engineering and Technology (BUET); Ligang Zhang, Central South University; Sehoon Yoo, Korea Institute of Industrial Technology; Vesa Vuorinen, Aalto University; Yu-Chen Liu, National Cheng Kung University; Ting-Li Yang, National Yang Ming Chiao Tung University
Tuesday 8:00 AM
March 21, 2023
Room: Sapphire E
Location: Hilton
Session Chair: Shih-kang Lin, National Cheng Kung University; Sehoon Yoo, Korea Institute of Industrial Technology
8:00 AM Invited
Microstructure and Interface Evolution of Bare Cu-Cu Bonding Using Cu-Ag Composite Paste during High Temperature Application: Chuantong Chen1; Takuya Sekiguchi2; Katsuaki Suganuma1; 1Osaka University; 2Toppan Forms Co., Ltd.
Currently, the high cost of sintering Ag particles and the oxidation problem of sintering Cu particles under air conditions need to be solved for large-scale industrial applications. Herein, by proposing a micron-sized Cu particle and Ag–amino composite (Cu–Ag composite), a robustly bare Cu–Cu bonding was realized under a low sintering pressure and temperature (300°C) under air atmospheric conditions. The microstructure and interface evolution of bare Cu-Cu bonding using the Cu-Ag composite paste during high temperature aging were evaluated. The results suggested that the Cu–Ag composite as a die attach material has remarkable potential applications to a bare Cu substrate bonding in SiC power devices, which could meet the requirements of power electronics in high temperature application.
8:25 AM Invited
Machine Learning Models of Ultimate Tensile Strength and Elongation for Low-temperature Solder: Yu-Chen Liu1; Ahmad Kholik1; Shih-kang Lin1; 1National Cheng Kung University
Low-temperature solder is a key material in solving warpage issue arising from the rather high reflow temperature in the advanced electronic packaging. Currently, Sn-Bi solder system has been viewed as a promising material system for low-temperature solder. Nevertheless, (Bi) phase coarsening after thermal aging causes the brittleness of the solder and thus decreases the reliability in real application. Element doping is typically applied in tailoring the solder properties. However, it is not economically feasible to tailor properties in the multi-component system by trial-and-error method. Therefore, this study used machine learning method to build up models in predicting ultimate tensile strength and elongation of the as-cast and aged Sn-Bi-X solders, where X represents the doping elements. Series of model evaluation methods including cross-validations and cross-plots analysis suggested that the model showed some predictive ability. The model was then used in designing promising solder system.
8:50 AM
Effect of Trace Bi on the Mechanical Strength of Sn Solder Before and After Thermal Aging: Yu-An Shen1; 1Feng Chia University
Sn is essential for solder joints. Due to its weak strength, elemental additions into Sn to form Sn-rich solder alloys are common for practical applications. Bi is one of the typical additional elements because of its good hardness. Although some studies have found the solid solution and precipitation of Bi significantly reinforce the Sn matrix, the strengthening mechanism of Bi has not been understood clearly, especially for the Sn matrix with trace Bi additions. In this study, Sn-rich alloys with Bi of 2.5 and 5 wt.% were fabricated to figure out the strengthening mechanism of Bi. The hardness tests evaluate the strengthening changes before and after the Bi additions. Moreover, the strengthening mechanism of Bi can be supported by the microstructural changes after thermal aging at 150°C for one week. X-ray diffraction and scanning electron microscope with EDS and BSE exhibit the microstructural changes.
9:10 AM
Effect of Cu Addition on Mechanical Properties of In-Sn Alloy Before and After Isothermal Aging: Hiroshi Nishikawa1; Han Le Duy2; Hiroaki Tatsumi1; 1Osaka University; 2Hanoi University of Science and Technology
The tin-indium eutectic (In-48Sn) alloy is a promising candidate for low-temperature applications especially for flexible electronic devices owing to its low melting-temperature (118 ℃), good wettability, and high ductility. However, In-48Sn alloy has a low mechanical strength and low creep resistance. In this study, we investigated the effect of Cu addition on microstructure and mechanical properties of In-Sn alloys before and after isothermal aging at 60 ℃. The results revealed that the microstructure of In-Sn-Cu alloy was clearly refined by Cu addition. The fine microstructure led to enhance tensile strength of In-Sn-Cu alloy compared to that of In-Sn alloy. Moreover, the two kinds of intermetallic compounds (IMCs) were formed in the In-Sn-Cu alloy, which also supported for the improvement of tensile strength of the alloy. Then, the Cu addition enhanced thermal stability of In-Sn alloy and In-Sn-Cu had better thermal stability than In-48Sn.
9:30 AM Break
9:50 AM
A Novel Synthesis Method of Cu NWs by Nucleation Control: Kuan Lin Fu1; 1National Central University
Cu NWs have emerged as a promising alternative to Ag NWs due to its high intrinsic conductivity, high abundance, and low cost. The synthesis literature of Cu NWs is very sufficient now. The most well-known one is hydrothermal which mainly by adding copper precursors, reducing agents and solvent, and capping agents or facet-selective promoters reacted at the high temperature. However, the current synthesis methods are all carried out at low concentrations, and the high-yield methods are often used by increasing the reaction volume, which does not effectively improve the use efficiency of the reactor. Both above result in the high cost and difficulty applying in the industry. Therefore, a kind of hydrothermal method controlling the kinetics of the synthesis process is proposed here to effectively increase the reaction concentration in the reaction process to increase the productivity per unit volume, so as to synthesize low aspect ratio Cu NWs.
10:10 AM
Dissolution Behavior in the Cu-2.0 wt% Be Alloy (Alloy 25) in Molten Sn, SAC305, and Sn-58Bi Solders: Andromeda Dwi Laksono1; Yee-wen Yen1; 1National Taiwan University of Science and Technology
The interfacial reactions between Cu-2.0 wt% Be alloy (Alloy 25) and lead-free solders had been investigated in our previous study. However, there still is lacking information in the Alloy 25/lead-free solders systems. This study investigated the dissolution behavior and kinetic of Alloy 25 in molten Sn, Sn-3.0Ag-0.5Cu (SAC), and Sn-58Bi (SB) solders at 240, 270 and 300℃. The dissolution rate in each system was increased when the temperature was increased. The dissolution rate of Alloy 25 in molten solder were calculated and followed the order Sn > SAC305 > SB. The planar Cu3Sn and scalloped Cu6Sn5 phases were formed at the solder/Alloy 25 interface. The Ag3Sn phase was precipitated among Cu6Sn5 grain in the SAC/Alloy 25 system. The thickness of the Cu6Sn5 and Cu3Sn phases increases with the increase of the dissolution times and temperatures. The thickest IMC thickness and the highest dissolution were found in Sn/Alloy 25 system.
10:30 AM
Interfacial Reactions in the Lead-free Solders/Cu-Fe Alloy(C194) Couples: Yi-Chin Liu1; Yu-Yen Lee1; Yee-Wen Yen1; 1National Taiwan University of Science and Technology
In this study, the solid/solid state interfacial reactions between the lead-free solders and Cu-2.35 wt.% Fe alloy (C194) were investigated. Three lead-free solders (LFS): Sn, Sn-3.0wt.%Ag-0.5wt.%Cu (SAC) and Sn-0.7wt.%Cu (SC) were first reacted with C194 at 245℃ for 15 s to form the LFS/C194 couple. Then the LSF/C194 couples were aged at 125,150 and 175℃ for 100 to 2000 h. The scanning electron microscope (SEM) and SEM with energy dispersive spectrometer (SEM/EDS) to examine surface morphology and intermetallic compound (IMC), respectively. The Cu6Sn5 phase was formed in all couples and its thickness was increased with the increase of aging times and temperatures. The Cu3Sn phase was formed at higher temperature and longer aging time. The Fe could inhibit the Cu3Sn phase growth. The total IMC growth mechanism is diffusion controlled in all LFS/C194 couples.
10:50 AM
Solid/Solid State Interfacial Reactions between Lead-free Solders
and Cu-Ti Alloy(C1990HP): Hsiang Yu Chiu1; 1National Taiwan University of Science and Technology
Interfacial reactions between lead-free solders (Sn, Sn-3.0Ag-0.5Cu (SAC) and Sn-0.7Cu (SC) alloys) and Cu-3.5wt% Ti alloy (C1990HP) by using the solid/solid reaction couple technique were investigated in this study. C1990HP first reacted with solders at 240°C with 15 s to form the solder/C1990 HP reaction couples. Couples were then aged at 125, 150 and 175°C for 100, 200, 500, 1000 and 2000 h. The surface morphology was examined by SEM. The IMC composition was analyzed by SEM/EDS and EPMA. Both the compositional data and related phase diagrams were used to determine the IMC. The results show that adding Ti could inhibit the Cu3Sn phase growth, and promote the Cu6Sn5 phase growth. The periodic layer structure was observed in the Sn/C1990HP couple aged at 175°C for 2000 h. This IMC growth type shows very different comparing with that in the SAC/C1990 HP and SC/C1990HP or solder/Cu systems.
11:10 AM
Electric Current-induced Lattice Strain and Grain Orientation Change in Silver Strip: Shih-kang Lin1; Yu-Chen Liu1; Ciou-Ren Lee1; 1National Cheng Kung University
Electromigration is the electric current-induced atomic migration and causes microstructure change including void/hillock formation, grain rotation, etc. Although electromigration-induced grain rotation in anisotropic Sn material had been well studied, how grain orientation is changed in isotropic materials such as Ag is still not clear. In this study, in situ synchrotron-radiation-based X-ray diffraction revealed that electric current induced an instant lattice strain and the strain would reach a steady state. Based on transmission electron microscopic and electron backscatter diffraction observation, when the steady state strain exceeded a critical value, hillock formation, abnormal grain growth, dislocation density increase, and grain orientation change were observed. We discuss the underlying mechanism of the current-induced grain orientation change in terms of defect dynamics in this study.