The authors have precisely measured the frequency dependences of the complex relative permittivity in the normal and tangential directions, as well as the surface and interface conductivities for a copper-clad laminate dielectric substrate (AR-1000) in the frequency range 4–20 GHz. In this paper, based on these measured values, we calculate the frequency dependences of the attenuation constant α and the effective relative permittivity ε_eff for a 50-ohm microstrip line (MSL) using a 3-dimensional electromagnetic simulator (HFSS). The high precision of this estimate is verified from microwave measurements for a 50-ohm MSL fabricated on the AR-1000 substrate by an etching technique. Furthermore, an evaluation technique is proposed to estimate the dielectric, conductor, and radiation losses of the MSL separately and precisely using the HFSS. Thus, the influences of the unisotropic loss tangent of the substrate and rugged surface of a copper foil on α can be distinguished numerically using this technique. Finally, for a 50-ohm MSL with gold plating, the influence on α is estimated from the measured value of the conductivity of the gold plating layer.

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As wiring patterns have become miniaturized, a technique is required for increasing the adhesion strength between the copper-plated layer and the resin substrate, without roughening the substrate. In this study, a chemically adsorbed monolayer containing a pyrrolyl group and a polymerized polypyrrole film were introduced as an interlayer between the copper layer and the resin substrate to increase the adhesion strength. A cross-section of the treated sample was observed by scanning electron microscopy (SEM). It was confirmed that the treatment did not roughen the resin substrate. The adhesion strength was evaluated by a peel strength test. The best sample had a sufficient average adhesion strength of 0.98 kN/m, which was five times that of the untreated sample.

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We evaluated the warpage behavior of ball grid array (BGA) electronic packages during reflow heating. In the BGA packages, the warpage under reflow heating might disconnect several solder joints. Therefore, the warpage behavior should be investigated in order to make more reliable BGA packages. Our investigation found that the warpage behavior sometimes changes depending on the heating history. Furthermore, we found that the change in the warpage behavior is accompanied by a change in the thermal expansion behavior of the mold resin. Thus, the warpage behavior was analyzed by visco-elastic analysis while considering the change in the thermal expansion of the mold resin. The analysis agreed well with the experimental results. Accordingly, the change in the warpage behavior was found to be mostly caused by the change in the expansion behavior of the mold resin.

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In this paper, the etchability and corrosion resistance of a Ni–Cr–Mo seed layer for Two-layer FCCL (Flexible Copper Clad Laminate) are evaluated. It is clearly shown that the seed layer coated by sputtering has a high corrosion resistance because the crystal structure is close to amorphous. It is found that the corrosion resistance to chloride ions was enhanced by the addition of Mo to the Ni–Cr seed layer with the Mo content range from 0.5 to 4 mass%. The lower limit is determined by the electrochemical migration resistance, and the higher limit is determined by the etchability.

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In this paper, a FPC which has high flexibility and low insertion losses was investigated. We made several kinds of our original FPC which are constructed with Microstrip-Lines or Strip-Lines when changing various factors. These factors are the shape of the GND pattern, the width of the signal pattern, the thickness of the copper, and the thickness of the resin. We confirmed that the stability of the characteristic impedance and the S-parameter change form the shape of the GND pattern. An equilateral triangle GND pattern causes a circuit resonance. We concluded from the characteristic impedance and S-parameter data that a square is the best shape for the GND pattern and it is better to make the resin thicker and to extend the pattern width.

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