Abstract: A semiconductor package in which a ceramic substrate is joined to a copper stud by brazing. Between the substrate and the stud, first and second members are each fixed in place with a brazing material. The first member has a thermal expansion coefficient intermediate those of the copper stud and the ceramic substrate for reducing the thermal stress generated in the ceramic substrate. The second member prevents the ceramic substrate from being deformed by thermal stress. If the first member is, e.g., a Cu-W alloy used as the neck on the copper stud, it is possible to reduce the compressive stress generated in the ceramic substrate during cooling after the brazing. Further, the influence on the substrate by bimetallic deformation as a result of the combination of the copper stud and the Cu-W alloy is mitigated by a flexible second member, e.g., a copper foil. Thus, the ceramic substrate is brazed without involving any substantial stress thereon.

Abstract: A semiconductor package includes a base body, metallized layers formed on the base body and having a die-pad area and a wire bonding area, a solder flow prevention wall which is formed on the metallized layers between the die-pad area and a wire bonding area preventing solder from flowing to the wire bonding area while a semiconductor chip is being soldered to the die-pad area.

Abstract: A ventilator drive system includes a fan for exhausting an indoor air to the outdoors and introducing an outdoor air to an indoor side, an electric motor for driving the fan, a humidity sensor having a humidity sensing element which abuts against an indoor side surface of a room wall as close as possible or which is located so that heat is transferred from the room wall, and a control circuit for comparing a signal from the humidity sensor with a reference signal. The motor is energized when the relative humidity is increased to a reference level or above.

Abstract: A ventilator has a body in which an air-intake passage for introducing outdoor-air indoors and an air-discharge passage for introducing indoor-air outdoors are defined. An air-intake fan and an air-discharge fan are arranged in the passages, respectively. A filter is provided in the air-intake passage to filtrate air flowing through the air-intake passage. The flow resistance in the air-discharge passage is set higher than that in the air-intake passage.