The increasing sophistication of information in society and the impending 'Internet of Things' will require smaller and higher-performance electronic devices, and faster also signal transmission, Particularly printed circuit board materials, such as cyclo-olefin polymers (COP) and liquid-crystal polymers (LCP), have been drawn attention for their low dielectric properties. Circuitry formation on these materials need plating treatment. Plating techniques on surface-modification using UV irradiation have been reported, but irradiation times of approximately 5 and 10 min, respectively, to achieve sufficient adhesion strength. However, these long treatment times present a challenge to productivity. To address this problem, we performed experiments using an improved, high-power UV lamp, with the aim of reducing the time required for surface modification treatment. We achieved significant reductions in UV-irradiation processing time, achieving an adhesion strength comparable to that obtained by a conventional method by irradiating COP plates for 45 seconds and LCP plates for 75 seconds.

The adhesion force of electroless nickel–phosphorus (Ni–P) platings prepared on silicon nitride (SiN), aluminum (Al), and polyimide (PI) substrates using complexing agents of glycine, succinic acid, succinic acid with glycine, and succinic acid with malic acid was demonstrated for the application to wafer-level packaging in large-scale integrated circuits. The adhesion strength of Ni–P platings was investigated by the tape-peeling test and the universal mechanical strength tester. As results, no peeling of Ni–P films formed using glycine, succinic acid, and succinic acid with glycine were observed, although Ni–P films formed using succinic acid with malic acid showed peeling. Thus, Ni–P plating formed using succinic acid with malic acid gave the smallest adhesion force. In contrast, the adhesion force of Ni–P platings formed using succinic acid with glycine on SiN, Al, and PI was the largest, approximately 850 kg cm−2, among Ni–P platings formed using those complexing agents. The growth rate of Ni–P films formed using succinic acid, succinic acid with glycine, and succinic acid with malic acid was uneven on SiN, Al, and PI. In comparison, Ni–P plating formed using glycine provided uniform growth rate on SiN, Al, and PI.

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High infrared-absorption films having low cost and light weight are indispensable for infrared sensors. We developed IR-adsorption coatings with low-reflectance and low-transmittance at wavelengths of 3-13 µm, based on a copper electroplating film pretreated with chemical etching and subsequent blackening. The chemical etching and blackening respectively produced columnar and feather-shaped structures on a copper surface. The reflectance and the transmittance of the films were below 15% and below 1% at wavelengths of 3-13 µm, respectively. The current coating technique might be useful to develop high absorption, low cost, and lightweight infrared absorbers.

Miniaturization of electronic devices has been strongly pursued to facilitate ubiquitous computing. High-density packaging technology is a promising candidate for reducing device size. For producing high-density packaging, metallization is an important process. Electroless nickelphosphorus plating, the most popular metallization method, is available for insulator materials such as silicon nitride (SiN) and polyimide (PI). For this study, we investigated three materials for substrates, PI as a resin, SiN as a passivation film, and aluminum (Al) as a metal. The values of adhesion strength between the electroless Ni-P film and three substrates were evaluated quantitatively using a stud pull test. A commercially available weak alkaline degreasing agent (aluminum cleaner NE-6; Meltex Inc.) is effective for metallization of PI, SiN, and Al simultaneously without a zincate process. These three materials are common used for a wafer level chip size package (W-CSP), which is a newly developed high-density packaging technology. Using the degreasing agent, we obtain sufficient adhesion strength for three substrates: PI, SiN and Al. The optimum concentration of the degreasing agent is 45 g/dm 3 for all substrate materials. Results show that the electroless Ni-P plating process is suitable for metallization of high-density packaging.