No abstract

インバー合金電析膜の熱膨張特性 山本 貴代Thermal expansion properties of Invar (Fe-36 mass%Ni) alloy electrodeposits were investigated. The Fe-36 mass%Ni alloy electrodeposits from sulfate/chloride electrolytes using additives, saccharin sodium, and malonic acid. The electrodeposits, of about 150 μm thickness, had no crack. The thermal expansion curve showed that contraction of the electrodeposits occurred in the 270-420 ℃ range during first heating. During the first cooling and second heating, it showed the same behavior as that of melted Invar alloy. The coefficient of thermal expansion α (CTE) exhibited approximately α＝10×10 -6 /℃ for the as-deposited electrodeposits and approximately α＝1×10 -6 /℃ for electrodeposits annealed above 500℃ . The CTEs of the electrodeposits annealed above 500 ℃ showed excellent agreement with that of the melted Invar alloy. The decrease in the CTE resulted from the increase of the fcc phase in the electrodeposits caused by heat treatment.Invar alloy electrodeposits are anticipated for application to high-definition electroformed products with low CTEs. Keywords

Fe-Ni-B alloy thin films were prepared by using an electroless plating method, and their thermal-expansion behavior, thermal-stress generation, and crystal structure were evaluated. By heating from 30 • C to 300 • C, the electroless-plated Ni-5 wt%B alloy film showed a marked increase in tensile stress at approximately 270 • C, which is caused by a phase separation from the amorphous Ni-B alloy into a highly crystalline Ni and Ni 3 B compound. The coefficient of thermal expansion (CTE) of electroless-plated Ni-B alloy film from 300 • C to 30 • C, after heating to 300 • C, was 14 ppm/K. In contrast, the electroless-plated Fe-Ni-B alloy film in the Invar composition range had a small CTE (8 ppm/K to 9 ppm/K) and no substantial change in crystal structure during heating to 300 • C. As a result, the Fe-Ni-B alloy film on the silicon substrate (CTE = 3 ppm/K) exhibited a low thermal stress compared with the electroless-plated Ni-B alloy film. Thus, it is suggested that the electroless-plated Invar Fe-Ni-B alloy films are suitable as an under-bump metal layer from the viewpoint of the thermal-expansion behavior.

Low CTE and fine pitch metal masks were fabricated by the invar Fe-Ni alloy electroforming process. The invar Fe-Ni alloy metal masks obtained had finer 10µm x 30µm rectangular open areas with a thickness of about 10µm. The CTE of the electroformed FeNi alloy fine pitch metal mask was 10ppm/K for the as-deposited mask and higher than the melted invar alloys. On the other hand, the CTE of the mask with annealing at 873K exhibited approximately 3ppm/K and was 4 times less than that of conventional electroformed Ni and Ni-Co alloys. The electroformed invar Fe-Ni alloy metal masks obtained are anticipated for use in the vapor deposition process for large and fine pitch OLED displays.

An electroplating–anodising method based on a facile and scalable electrochemical process was used to fabricate manganese ferrite porous oxide films for use as precious-metal-free oxygen reduction/evolution reaction (ORR/OER) electrodes. Porous...

Practical plating baths and plating conditions for preparing Fe–Ni alloy electroplated films with compositions in the Ni content range 36–100 mass% have been proposed. The addition of saccharin in sulfate-chloride bath is indispensable for preparation of Fe-30–45 mass% Ni alloy electroplated films, i.e., those in invar composition region. The addition of tartaric acid or malonic acid to Fe–Ni alloy plating baths (containing saccharin) prevents a reduction in the toughness of the plated film by masking Fe3+ generated by oxidation. It was possible to suppress the internal stress in invar Fe–Ni alloy electroplated films to low levels. Resultantly, the invar electroplated films obtained from these optimized plating baths show promise for electroforming. On the contrary, the addition of citric acid, which forms a more stable complex with Fe3+, causes very large internal stress in the resultant invar Fe–Ni alloy electroplated films, making them unsuitable as MEMS materials. It was confirmed that Fe–Ni alloy electroplated films with Ni contents of 45–100 mass% comprise a single-phase alloy having an fcc structure but the invar Fe-36–42 mass% Ni alloy electroplated film is a metastable bcc phase or a mixture of bcc and fcc phases. Therefore, to impart low thermal expansion characteristics to as-plated invar alloy films, it is necessary to induce phase transformation to an fcc phase, which is the equilibrium phase at high temperature, by the means of heat treatment.

Recently the regulation of nickel usage because of allergy issues has been strengthened in Europe and other countries. The Cu-Sn alloy (40-55 mass%Sn) is called “speculum alloy” or “white bronze” and has a silvery-white appearance. We developed a noncyanide Cu-Sn alloy plating bath consisting of sulfosuccinic acid, L-methionine and polyoxyethylene-α-naphthol, from which silvery-white Cu-Sn alloy (40-55mass%Sn) were obtained. It is anticipated that the Cu-Sn alloy films will be used as an alternative to nickel undercoating for decorative gold or chromium electroplating.

No abstract