• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.9-17
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• 2011

Nano-composite solders have been studied to improve the properties of Pb-free solder joints. The nanoparticles in the composite solders were carbon nanotubes(CNTs), metals (Ag, Ni, Cr, etc.), ceramics (SiC, $ZrO_2$, $TiB_2$, etc.). To fabricate the nano-composite solders, mechanical mixing methods and in-situ fabrication method has been used for well-dispersed nano phase. The characteristic properties of the nano-composite solders were high creep resistance, low undercooling, low IMC growth rate and fine microstructures. More researches on the nano-composite solders are required to improve the processibility and the reliability of the nano-composite solder joints.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.1-6
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• 2019

Wettability is an important factor to decide solderability of solder, flux, other soldering-related materials and soldering conditions. The wettability also affects the reliability of solder joint. Wetting balance test is a good method for quantitatively measuring wettability between solder and substrate. The wetting balance test is easy to reproduce the wetting experiment and to measure the wetting time and force. And this test provides wetting curve to calculate the surface tension of the molten solder. Development of new solder has been continued in accordance with various and harsh environment in the electronics industry. In this paper, the principle of wetting balance test and recent research issues including nano-composite solder are explained.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.31-37
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• 2021

Sn-3wt%Ag-0.5wt%Cu (SAC305) solder is most popular solder in electronics industry. However, SAC305 has also drawbacks such as growth of β-Sn phase, intermetallic compounds (IMCs) of Ag3Sn, Cu6Sn5 and Cu3Sn which can result in deterioration of solder joints in terms of metallurgically, mechanically and electrically. Thus, improvement of SAC305 solders have been investigated continuously by addition of alloying elements, nano-particles and etc. In this paper, recent improvements of SAC solders including nano-composite alloys and related solderabilty and metallurgical and mechanical properties are investigated.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.68-73
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• 2014

Among through silicon via (TSV) technologies, for replacing Cu filling method, the method of molten solder filling has been proposed to reduce filling cost and filling time. However, because Sn alloy which has a high coefficient of thermal expansion (CTE) than Cu, CTE mismatch between Si and molten solder induced higher thermal stress than Cu filling method. This thermal stress can deteriorate reliability of TSV by forming defects like void, crack and so on. Therefore, we fabricated SiC composite filling material which had a low CTE for reducing thermal stress in TSV. To add SiC nano particles to molten solder, ball-typed SiC clusters, which were formed with Sn powders and SiC nano particles by ball mill process, put into molten Sn and then, nano particle-dispersed SiC composite filling material was produced. In the case of 1 wt.% of SiC particle, the CTE showed a lowest value which was a $14.8ppm/^{\circ}C$ and this value was lower than CTE of Cu. Up to 1 wt.% of SiC particle, Young's modulus increased as wt.% of SiC particle increased. And also, we observed cross-sectioned TSV which was filled with 1 wt.% of SiC particle and we confirmed a possibility of SiC composite material as a TSV filling material.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.35-41
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• 2022

In the era of Fifth-Generation (5G), technology requirements such as Artificial Intelligence (AI), Cloud computing, automatic vehicles, and smart manufacturing are increasing. For high efficiency of electronic devices, research on high-intensity circuits and packaging for miniaturized electronic components is important. A solder paste which consists of small solder powders is one of common solder for high density packaging, whereas an electroplated solder has limitation of uniformity of bump composition. Researches are underway to improve wettability through the addition of nanoparticles into a solder paste or the surface finish of a substrate, and to suppress the formation of IMC growth at the metal pad interface. This paper describes the principles of improving the wettability of solder paste and suppressing interfacial IMC growth by addition of nanoparticles.