In the development of epoxy materials for the printed wiring boards of high-speed communication devices, we have developed a curing agent with a low dielectric constant and low dielectric loss tangent. By developing the basic technology of the active-ester type epoxy resin curing agent announced in 1991, we have succeeded in developing a new polyfunctional oligomer type active-ester type epoxy resin curing agent which can be used as a material for electronics. Compared with the widely used phenol novolac curing system, a significantly lower dielectric constant and lower dielectric loss tangent have been achieved whilst maintaining a high glass transition temperature. It is considered that the centrally-located dicyclopentadiene skeleton exhibits an excellent low dielectric constant and low dielectric dissipation factor whilst maintaining heat resistance due to its rigidity, small molar polarisability and large molar volume.

We found two slope change points (0.25 and 8 h) in the electric resistance of Cu wiring between 0 and 100 h by performing an oxidation process at 150°C on printed circuit boards (PCB). We formed a Pt film on Cu by sputtering and used STEM (Scanning Transmission Electron Microscopy) and AES(Auger electron spectroscopy) to investigate the formation process of the oxide film growing as the boundary of the Pt film. Our results show that the growth rate of the oxide film between the two slope change points (0–0.25 h, 0.25–8 h) was linearly regressed against the oxidation time, indicating that the change in the growth rate of the oxide film was affected by the passage of time. We found that the main oxide film structure formed between 0 and 8 h was Cu₂O, and after 100 h, a thin layer of CuO started to form on top of the layer of Cu₂O.

In the case of a high sensitivity strain measurement device that has an adhesive bonding part, a small zero-point drift (sensor output value drift before and after load) caused by the change in physical properties of the adhesive bonding part appears clearly as a measurement result. Therefore, it is necessary to predict and evaluate it quantitatively. In this research, we propose a zero-point drift prediction technology using viscoelastic stress analysis in which an adhesive that bonds a strain measurement device to objects is modeled with a viscoelastic body. We conducted the viscoelastic stress analysis and the verification test for a constant load test using a semiconductor strain sensor. Our results confirm that it is possible to predict the zero-point drift accurately because the analysis results coincided with the test results within ± 1 με.

In this paper, an analysis design method of T-shape passive equalizer circuits for high-speed digital cable transmission is proposed. The design is based on the fact that the circuit constant is uniquely determined by the DC value of the transfer function and the frequency where the transfer function is the square root of the DC value. This design method was applied to a 3.125 Gbps digital signal transmission of a 10 m long differential cable, and the validity of the method is confirmed since the transmission characteristics of the equalizer and the cable were constant in a range of ±1 dB in a signal band of 1.25 GHz. Furthermore, the effectiveness of the method was proved, since the value of the transmission characteristic measured with an evaluation circuit board was as designed and total jitter was suppressed under the XAUI standard using the eye pattern evaluation.

LSI packages for high-reliability space-use are hermetically sealed ceramic with cavities. In recent years, in order to increase the number of inputs & outputs (I/O) or pads and reduce size and weight, ceramic Ball-Grid-Array (BGA) packages have become more common and thermal cycle tolerance has become a significant issue in substrate mounting. Underfill material is often applied to improve the thermal cycle tolerance, but there are failures where the underfill peels off from the bottom of the package early in the thermal cycle test. In this paper, we report on an underfill material that protected the terminals without peeling off under a thermal cycling load of more than 3,000 cycles. We also report on indications of defects found in areas other than solder balls or connecting areas.