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Abstract We investigated the effect of Ag-coated multi-walled carbon nanotubes (Ag-MWCNT) on the microstructures and electromigration behaviors of a Sn58%Bi solder and organic solderability preservative (OSP) surface finished on the FR-4 printed circuit board (PCB) joint under a current stress of 3000 A/cm2 at 100 °C. Electromigration of Ag-MWCNT Sn58%Bi composite solder was investigated by daisy-chain test-kit. Reaction layers formed at the anode side and cathode side of the Sn58%Bi solder joints consisted of three microstructures; Bi-rich layer, Sn-rich layer, and intermetallic compounds (IMCs, Cu 6 Sn 5 and Cu 3 Sn). The Bi-rich layer was mainly formed at the anode side in the couple of the Sn58%Bi solder joint with various times of applying current stress. The Bi-rich layer of the Ag-MWCNT Sn58%Bi composite solder joint was approximately 2 times thinner than that of the Sn58%Bi solder joint because the Ag-MWCNT acts as a diffusion barrier. Also, the Cu 6 Sn 5 and Cu 3 Sn IMCs that formed at the interface between the Ag-MWCNT Sn58%Bi composite solder joints were thinner than those of the Sn58%Bi solder joints. The time to failure (TTF) was longest at the 0.05% Ag-MWCNT Sn58%Bi composite solder joint. Therefore, Ag MWCNT is expected to improve the reliability of electromigration in the Sn58%Bi composite solder joint. Highlights • The electromigration of the Ag-MWCNT Sn58%Bi composite solders were investigated. • Ag-coated MWCNTs were widely distributed in the Sn58%Bi solder joint. • MWCNT suppressed growths of Cu-Sn IMCs and Bi-rich layer under current stress. • TTF value of the 0.05 wt% Ag-MWCNT Sn58%Bi composite solder joint was the longest. [ABSTRACT FROM AUTHOR]

High heat-endurance bonding between Cu Ni was investigated by hybrid transient liquid phase sintering bonding. By simultaneously adding Cu and Ni to SAC305, the IMC was stably formed, and the bonding strength of hybrid TLPS joint was the highest. It is expected to be used for SiC die attachment of power module packaging. [Display omitted] • Novel hybrid transient liquid phase sintering bonding is developed for Cu Ni bonding. • Fast and stable ternary (Cu,Ni)-Sn IMCs were formed by hybrid transient liquid phase sintering bonding. • Electron probe micro-analyzer was used for investigating the atomic distribution of TLPS joints. A novel approach to copper-nickel bonding was investigated by hybrid transient liquid phase sintering (TLPS) method. Hybrid bonding material containing copper, nickel, and Sn-3.0Ag-0.5Cu (SAC305) and an organic solvent was fabricated to form a fast and stable ternary Cu Ni Sn intermetallic compound (IMC) joint between Cu to Ni joint. The atomic distribution was analyzed by an electron probe micro-analyzer, showing full IMC formation of the hybrid TLPS joint. In addition, by simultaneously adding Cu and Ni to SAC305, the IMC was stably formed, and the bonding strength of hybrid TLPS joint was the highest. [ABSTRACT FROM AUTHOR]

A carbon nanotube (CNT) has remarkable properties, but it has disadvantages in application because of its dispersal- and bonding-related issues. Metal–CNT composite materials are necessary in solving these problems. In this study, nickel (Ni)–multi-walled CNTs (Ni–MWCNTs) are synthesized through sequential processing, functionalizing, and electroless plating processes to deposit Ni nanoparticles on MWCNTs. The synthesized Ni–MWCNTs are used to fabricate composite solders with various contents (0, 0.05, 0.1, and 0.2 wt%). The test kit used for the 3-point bending test in this study is designed with a differential package structure to evaluate the bending reliabilities of the Ni–MWCNT composite materials with various contents. The crack initiation and propagation in the microstructure evolution solder joints are also investigated. The bending reliabilities improve with the BGA structure and indicate that the highest bending cycle fails with 0.1 wt% of Ni–MWCNTs. The chemical composition and distribution of the Ni–MWCNTs in the solder joints are investigated with electron probe microanalysis. • Test-kits for 3-point bending test were designed with differential structure. • Bending test was performed to evaluate the mechanical properties of solder joints. • Ni-MWCNTs composite solder could improve the bending reliability of Sn58Bi solder. [ABSTRACT FROM AUTHOR]

A Cu-cored solder ball (CCSB) is often used as the interconnection material for 3D package. The CCSB has a Cu core surrounded by Sn-Ag-Cu alloy. The effect of the Cu core on mechanical reliability of the CCSB was investigated using thermal shock test. Microstructure and thermal shock reliability of the CCSB with organic solderability preservative (OSP) surface finish was compared with that of Sn-3.0wt.%Ag-0.5wt.%Cu (SAC) solder. The thermal shock test was performed in the temperature range of −40 °C to 125 °C in compliance with JESD22-A104. Failure mechanism was analyzed by finite element method analysis. Average number of thermal shock cycles for the CCSB/OSP joints was 1.15 times higher than that for SAC/OSP joints. Maximum value of simulated plastic strain for the SAC/OSP joints was 1.25 times higher than that for the CCSB/OSP joints because the stand-off height of the CCSB/OSP joints could be maintained by the Cu core. • Thermal shock reliability of Cu cored solder joint was investigated. • Simulated stress and strain were reduced because stand-off height of solder ball was maintained by Cu core. • Crack of solder joint was propagated through the solder matrix that was highest simulated plastic strain regions. • Thermal shock reliability of solder joint was improved due to stand-off height. [ABSTRACT FROM AUTHOR]