Takashi Okada

Effectiveness of Thin‐film Barrier Metals for Eutectic Solder Bumps

This paper describes effective thin‐film structure barrier metals for use as eutectic solder bumps. Shear strength and bump interconnection resistance were evaluated. The mutual diffusion in metals was investigated. Barrier metal structures —Cu/Ti,Ni/Ti and Cu/Cr—were evaluated after ageing. The Ni/Ti structure has good reliability according to ageing test results. Pd is used for improvement of solder wettability and as an oxidisation barrier. Consequently, it was concluded that a thin‐film Pd/Ni/ Ti barrier metal is suitable for use as eutectic solder bumps. The broken interfaces of the solder bumps were analysed by scanning auger electron spectrometry. In the thin‐film Cu/Ti structure, decrease in the shear strength is caused by three mechanisms, as determined from the broken interface analysis. The three mechanisms are mixed metal formation, Ti oxidisation and diffusion between barrier metals and Al. Furthermore, TCT and PCT were carried out on these eutectic solder bumps to confirm the interconnection...

Characterization of net configurations for multichip modules

An investigation of the design considerations for MCMs based on CMOS VLSI has been carried out with the aim of achieving a higher performance system. Included in the investigation were output driver and receiver characteristics and net configurations in MCM. Four MCM types have been introduced: MCM-D, MCM-Si, MCM-C, and MCM-L. Time domain analysis using the SPICE simulation program was carried out taking into consideration a lossy transmission line model. A simpler criterion for the critical damping condition and an estimation method for the signal delay of the network with a lumped circuit approximation is proposed to determine a preferable interconnect network including the output driver and the loads. The effect of the net configuration was also analyzed and the preferences among the net configurations have been represented with only two net parameters, the total net length and the far-end length.<<ETX>>

43.4: An In‐Cell Capacitive Touch‐Sensor Integrated in an LTPS WSVGA TFT‐LCD

We have developed an in-cell capacitive touch-sensor integrated in an LTPS 7″ WSVGA TFT-LCD. The prototype having 256×150 sensors shows advantages such as smooth operation with no touch force, high position accuracy, multi-touch (10 or more), thin and light LCD module, and thus is suitable for various applications.