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The possibility of the surface-activated bonding (SAB) technologies for fabricating III-V-on-Si hybrid tandem solar cells is discussed. Although the electrical conduction across the bonding interfaces is influenced by the interface states introduced during the surface-activation process, their impacts are likely to be lowered by combining more heavily-doped bonding layers and the annealing process...
Liquid-gas heat exchanger has been developed for subcooling-superheating process of vapor compression refrigeration cycle. Refrigeration cycle utilizes low pressure refrigerant, which facilitates in easy piping installation and spill-proof operation. Experimental and numerical studies have been performed in order to quantify and understand thermal-hydraulic behavior of subcooling-superheating (liquid-gas)...
This paper discusses both thermal management of a microrobot and a control IC. The developed microrobot is fabricated by the MEMS (Micro Electro Mechanical Systems) technology. The miniature actuator is constructed by SMA (Shape Memory Alloy) wires and a rotor. It shows rotational motion by heating and cooling process of the SMA wire. Moreover, artificial neural networks are used for the miniature...
Two types of additive combinations are used in the Cu plating solution to prepare the Cu deposits. The Cu deposit prepared with PEG and Cl− results in the formation of a specular structure composed of voids, Cu-impurity compounds, and intermetallic compounds when it reacts with Sn. The specular structure exhibits a very fast growth rate which is unusual for the Sn/Cu interfacial reaction. Introduction...
Subcooled pool boiling heat transfer is evaluated for Long Life Coolant (LLC) that is a binary mixture of water and ethylene-glycol (EG). The experiments are conducted at the concentration of 30 vol.% solution of EG in water and 30 vol% solution of LLC in water under the atmospheric pressure. The liquid subcooling is 50 K. Although the boiling curve for the EG solution shows the same tendency as that...
The different of Ag-11Au-4.5Pd and Ag-11Au-4.5Pd-0.1Y alloy bonding wire mechanical properties, fusing current and structure were analyzed by strength tester, electronic conductivity tester, and scanning electron microscope. The effects of Y on Ag-11Au-4.5Pd and Ag-11Au-4.5Pd-0.1Y alloy bonding wire ball size, bonded micro phonology and bonded strength were investigated. The results show that the...
In this study, we investigated effects of thermal gradient of joint during flip chip bonding on intermetallic compound (IMC) growth for several solder materials. Cu/Sn-2.5Ag/Cu joint was prepared by bonding electroplated Cu/Sn-2.5Ag bump on Cu pad. Ni/Sn/Ni, Ni/In/Ni, Ni/In-48Sn/Ni, and Ni/Sn-58Bi/Ni joints were prepared by solder capping by IMS on electro-less plated Ni/Au post and bonding it on...
Aiming for the improvement of the boiling heat transfer coefficient, the effect of the nano-coated heating surface was investigated. We used a silane coupling agent to change the wettability of the heating surface. By means of the coated heating surface, we examined boiling curve of subcooled pool boiling. As a result, the boiling curve with the coating agent was drastically changed and microbubble...
This paper describes development of joint materials using only base metals (Cu and Sn) for power semiconductor assembly. The optimum composition at this moment is Cu8wt%Sn92wt% (8Cu92Sn hereafter) particles: pure Cu (100Cu hereafter) particles = 20:80 (wt% ratio), which indicates good stability under Thermal Cycling Test (TCT, −55°C∼+200°C, 20cycles). The composition indicated to be effective to eliminate...
A newly developed copper foil which is chemically processed has been introduced as nano anchoring copper foil for Printed Wiring Board (PWB). This treatment technology enables good adhesion even on the nano-scale surface roughness by conditioning a copper surface of nano-scale anchoring structure. The surface roughness of the copper foil affects fine patterning capability and transmission loss. Fine...
As the result of investigating the new additives for improving the fine pattern of the electroless Ni-P plating, high-valence metal ion was found. Especially Co3+ mostly inhibited deposition outside of pattern without step plating and decrease of corrosion resistance which is a problem in the conventional additives. It is considered that Co3+ + e− → Co2+, which is nobler reaction than Ni deposition,...
A corundum-structured α-Ga2O3 has been gathering attentions for its first operations of Schottky barrier diodes (SBDs) with a low on-resistance value of 0.1 mΩ·cm2. A growth of highly-crystalline α-Ga2O3 thin films were firstly reported by our group and new alloy system consisted with corundum structured oxides including α-Ga2O3 had established. In this conference, the details of our work on α-Ga2...
Due to large topographic gaps between the chips and mold substrate, the next generation of high density FO-WLP will require fine RDL plating resists that can achieve as low as 2um line/spaces(L/S) with a wider common depth of focus (DOF) margin. In order to meet these requirements, we developed a novel chemically amplified positive tone resist. In this study, we focused on photo acid generators (PAGs)...
This study evaluates boiling and evaporative heat transfer performance of a heat sink called EVAPORON-4 utilizing uni-directional porous media in order to remove high heat generation of 300–500 W/cm2 from a chip of the next generation SiC-/GaN-based on-vehicle inverter. The unidirectional porous heat sink has three functions such as direct supply of cooling liquid to a heat transfer surface, promotion...
Direct bonding of polyoxymethylene (POM) at 100 °C was feasible using self-assembly monolayers (SAM). The POM substrates were first activated by vacuum ultraviolet irradiation in presence of oxygen gas (VUV/O3) and then modified with SAM: (3-Aminopropyl)triethoxysilane (APTES) and (3-Glycidyloxypropyl)trimethoxysilane (GOPTS), respectively. Fourier transform infrared spectroscopy showed that both...
We proposed a novel fabrication method of a pillar patterned self-standing curved film by spherical soft-UV imprint lithography. Soft-UV imprint lithography was performed using a patterned polydimethylsiloxane (PDMS) mold and a convex mold in order to pattern pillar onto large curved film. A mother patterned mold of spherical soft UV imprint lithography was prepared by unique 3D printer method. The...
This research focuses on revealing the effect of size and shape of Ag particles for mechanical properties of no-pressure sintered Ag by using micro-compression test. Specimens were fabricated by focused ion beam with the dimension of 5 μm × 5 μm × 15 μm. The stress-strain curve suggested that the sintered Ag subjected a stable elastic deformation and a large plastic deformation. The mechanical properties...
In this paper, we demonstrate a high heat resistant bonding method by Cu/Sn transient liquid phase sintering (TLPS) method can be applied to die-attachment of silicon carbide (SiC)-MOSFET in high temperature operation power module. The die-attachment is made of nano-composite Cu/Sn TLPS paste. The die shear strength was 40 MPa for 3 × 3 mm2 SiC chip after 1,000 cycles of thermal cycle testing between...
The number of in-vehicle power devices has been increasingly for motor controlling purposes. Power device packages should ideally be small and easy to mount. We have developed a small power module by assembling several power devices sealed with molding resin. Two new techniques were used to produce this module: one was the use of copper clips for high-current wiring, and the other was low-cost soldering...
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