Tadashi Ariga

Microstructural change and hardness of lead free solder alloys

Two types of Pb free solder, Sn-Ag eutectic alloy and Sn-Zn eutectic alloy, as potential replacements for Sn-Pb eutectic solder and Sn-Pb eutectic alloy were found to age-soften during storage at room temperature (25 C, 298 K, 77 F) and high temperature (100 C, 373 K 212 F). The hardness of another type of Pb free solder, Sn-Bi eutectic alloy, did not change during storage at room and high temperature. However, the microstructure of Sn-Bi eutectic alloy coarsened unusually during storage at room and high temperature.

Brazing of CP-titanium/CP-titanium and titanium alloy/stainless steel with laminated Ti-based filler metal

Joining technology of CP-Titanium and Titanium alloy is very important for manufacturing field. In that case of titanium brazing, chemical compositions of brazing filler metal and brazing atmosphere are very important. In this study, CP-Ti/CP-Ti and Ti alloy/Stainless Steel were brazed with Ti-based laminated brazing filler metal by using continuous type furnace under Ar gas atmosphere containing extremely low oxygen. Laminated filler was fabricated by roll bonding technology. Chemical compositions of laminated filler metal used in this study were Ti-15Cu-15Ni and Ti-20Zr-20Cu-20Ni. Brazing temperature employed in this study was 850, 900, 950, and 1000 C. These brazing temperatures were based on thermal analysis results and alpha-beta transformation temperature of the base metal used in this study. Firstly melting properties of laminated brazing filler metal was investigated with DTA and DSC. Secondary joint characteristics were estimated by micro-structural observation at the joint and mechanical properties measurement. Sound joint was obtained in this study according to outside appearance of the specimen. Ti-20Zr-20Cu-20Ni filler had low melting point as compared with Ti-15Cu-15Ni according to thermal analysis results and fillet form-ability. Ni and Cu were diffused from molten brazing filler to base metal during brazing and Ti-Cu-Ni eutectoid reaction was took placed at the based metal during cooling after brazing.

Characteristic of low temperature of Bi-In-Sn solder alloy

Due to the increase in the use of electronics devices within the industry, the usage of solder connections has increased. These is a concern that lead within the electronic products is considered toxic because lead has potential for leaching from landfills onto water sources and becoming a hazard to human health and surrounding environment. For this reason, replacing Sn-37Pb to free solder with low melting temperature is one of the most important issues in electronic industry. This is due to a demand on low temperature for interconnection and polymer based part component such as LCD display functionality availability at low temperature apply. In this paper, Bi-In-Sn system alloy was investigated as a potential candidate replacing Sn-37Pb. This study covers on solder characteristic such as melting temperature, thermal expansion and microstructure. Bi-In-Sn was prepared and melted in crucible. Solder was cleaned mechanical and chemical before characterized. DSC shows that, Bi-In-Sn system alloy give low melting temperature in range of 65-100°C. The addition of In to Bi-Sn system alloy lowered the melting temperature compared than Sn-37Pb. Lowest melting temperature ensures that the solder melts, forms a joint with the substrates, and re-solidifies within the shortest possible process time. From thermal expansion analysis, it was found that Bi-In-Sn gives good expansion properties to avoid mismatch between Cu pads and solder itself. EDX analysis indicated that, there are two obvious regions in Bi-In-Sn system alloy microstructure. Bright colour refers to BiIn rich phase region and dark colour refers to Sn rich phase region. BiIn rich phase region is higher compared to Sn rich phase in solder give good properties in terms of ductility.

Formulation of the size and position of spiral cooling channel in plastic injection mold based on Fluent simulation results

This paper presents a formula based on simulation results using Fluent software to determine the size and position of a spiral cooling channel in a plastic injection mold that yields the maximum effect on the ratio of product cooling rates and coolant pumping energy (CR/PE). In this formulation, there are 5 simulation steps performed: Re, Ac/Ap, Lc/Lp, rca/rp and kmold. The formulat was developed by doing a step-by-step optimization using the CR/PE parameter on the simulation results by considering uniformity of product temperature during cooling (U). By performing mathematical processing on the optimization results, we obtained a targeted formula with product dimension and mold thermal conductivity as entry variables. The validity of the formulat is supported by the fact that it was developed from simulation results that have fulfilled convergence criterion, a high percentage correction factor (above 97%) for all interpolations performed and a good level (approximately 96%) in the uniformity.

Interfacial Reaction Analysis of Cu-Sn-Ni-P/Cu Joint Using Microwave Hybrid Heating

Microwave hybrid heating (MHH) technique was used to investigate the formation of intermetallic compound layer at Cu-7.0Ni-9.3Sn-6.3P/Cu interface. Two different susceptor materials; graphite and silicon carbide were used to provide initial heating of the filler alloy before it starts couple with the microwaves and melted on the Cu surface. The interface of IMC layer was characterized using Scanning Electron Microscope (SEM), energy dispersive X-ray spectrometry (EDS) and microhardness. Metallurgical study showed the formation of the IMC layer with multiphase at the joint interface for microwave heating of both susceptor materials. The thickness of IMC layer heating in silicon carbide susceptor was three times thinner than heating in graphite susceptor; 16.5 μm and 50.5 μm, respectively. The findings showed that microwave hybrid heating can be used to join Cu-7.0Ni-9.3Sn-6.3P/Cu and controlled the thickness of IMC layer.

Effect of microwave hybrid heating on the formation of intermetallic compound of Sn-Ag-Cu solder joints

Microwave hybrid heating (MHH) technique was used for investigate the formation of intermetallic compound layer at Sn-3.0Ag-0.5Cu/Cu interface. 4g and 6g of graphite powder were used as susceptor to provide initial heating of the solder alloy before it starts couple with the microwaves and melted on the Cu surface. The IMCs interface was characterized through Field Emission Scanning Electron Microscope (FESEM), Electron Dispersive X-ray (EDS), X-ray Diffraction (XRD) and nanohardness. Microstructural study showed the formation of Cu6Sn5 and Cu3Sn IMCs at the Sn-3.0Ag-0.5Cu/Cu interface after 120s, 150s and 180s microwave heating time. The Cu6Sn5 IMC scallop-like and angular trapezoid structure are formed after 180s microwave heating time with 4g and 6g of graphite powder respectively.

Microstructural analysis of brazing sapphire and Inconel 600 for sensor applications

Abstract The development of sapphire-based sensors for gas pressure application is growing in demand because of their appealing characteristics that could withstand high temperatures and harsh operating conditions. However, the joining process of sapphire to other materials, especially metals, is difficult to achieve because of dissimilar physical and mechanical properties. In this study, a direct brazing process was successfully demonstrated to bond sapphire to sapphire and sapphire to Inconel 600 using BAg-8 + 1·5Ti filler metal. Silver-based brazing filler metal with active element of Ti was believed to promote wetting in brazing of ceramic surfaces. The results have shown that a reaction layer is present between the sapphire and the brazed layer. There is also a variation in the phase formation between the sapphire/sapphire and the sapphire/Inconel 600 joints because of the influence of elements from the Inconel 600.

Formation behaviour of reaction layer in Sn-3.0Ag-0.5Cu solder joint with addition of porous Cu interlayer

The morphology and growth of interfacial intermetallic compound (IMC) between Sn-3.0Ag-0.5Cu solder alloy and Cu substrate metal of solder joint is reported. The IMC morphology and IMC thickness layer were observed at three different porosities of porous Cu interlayer. The results revealed that during soldering process, Cu6Sn5 compound with scallop like morphology was formed at the interface of both the solder alloy and Cu substrate and at solder alloy and porous Cu interlayer. By adding porous Cu interlayer at the solder joint, the IMC thickness increased with increasing soldering temperature and the number of pores in porous Cu interlayer. The effect of porosity on increasing the IMC layer was also due to the slower cooling rate during solidification of molten solder.

Effect of Isothermal Aging on Mechanical Properties of Sn-3.0Ag-0.5Cu Solder Alloy with Porous Cu Interlayer Addition

The performance of Pb-free SAC305 solder joint added with porous Cu interlayer was investigated. The porous Cu interlayer was placed in a sandwich-like layer between SAC305 solder alloy and rod Cu as the substrate metal. Two different pores, 15 ppi (pore per inch, P15) and 25 ppi (P25) with the pore size approximately ϕ1.7 and ϕ1.0 mm, respectively were used. The soldering process of solder joint was carried out in three different soldering temperatures of 267, 287 and 307 °C while the holding time was set at 300 s. Tensile test was performed to evaluate the joining strength of the solder alloy with loading rate of 0.5 mm/min. The highest joint strength was recorded at 53 MPa when soldered with P25 porous Cu interlayer at 307 °C. High thermal aging test was performed in an oven, heated to temperature of 150 °C for aging time of 100, 200 and 500 h to investigate the heat and time effect on the joint strength. The results indicate the reduction of strength at the aged sample with the increased aging time. The crack initiates dominantly at the interfaces between the porous Cu/SAC305. In general, solder joint soldered with P25 of porous Cu joints have greater tensile strength (23 MPa) than P15 of porous Cu interlayer after aging test.

Influence of indium and zinc oxide nano-particles on properties of SAC0307-xIn-yZnO lead-free solder paste

The influence of indium (In) and zinc oxide (ZnO) nano-particles on the properties of SAC0307-xIn-yZnO lead-free solder paste was presented in this paper. Solder paste was mixed with indium and zinc oxide nano-particles at various concentrations. The influence of these particles on melting point. wettability and interfacial layer after soldering with copper substrate was investigated. The results showed that the addition of lower levels of indium and zinc oxide nano-particles could reduce the melting temperature of SAC0307. Wettability of the solders on copper substrate in terms of contact angle was obviously decreased with the increase of appropriate indium and zinc oxide nano-particle concentration. The zinc oxide nano-particles affected the thickness value of the intermetallic layer. giving it a lower and more uniform distribution between the solder and copper substrate.