Abstract: A groove having a V-shaped section is provided on a bonding surface of an IC chip being as a first small part, while an elongate projection having a V-shaped section to engage with the groove of the first IC chip is provided on a corresponding portion of a bonding surface of an IC chip being as a second small part. Then, the IC chips are bonded together by the action of a holding force resulting from fitting the elongate protection of the second IC chip to the groove of the first IC chip, together with a bonding force produced between the bonding surfaces by interatomic force and metallic bond.

Abstract: An interface unit includes an optical interface circuit outputting a transmitting signal for driving an optical driver in response to input data, a serial interface circuit outputting a transmitting signal for driving a serial driver in response to the input data, a terminal for outputting a signal, and a circuit part for selectively outputting the transmitting signal from one of the optical interface circuit and the serial interface circuit via the terminal, so that at least a pulse width of the transmitting signal output via the terminal satisfies a standard established with respect to the optical driver when the output transmitting signal of the optical interface circuit is output via the terminal.