Abstract: A circuit board includes a copper plate and an insulating layer of photosensitive polyimide resin formed on the copper plate, the insulating layer leaving an exposed portion of a surface of the copper plate where an LSI is to be mounted. After Au plating is applied to the exposed surface of the copper plate, the LSI is mounted fixedly. A connection pattern having bonding pads is formed by copper plating on the insulating layer. The bonding pads and the LSI are connected by Au wire bonding on the Au plating applied on the bonding pads.

Abstract: A method for etching a chromium film includes the steps of forming a resist having a phenol novolak resin as a principal chain on the chromium film formed on a substrate, and etching the chromium film using an etchant while stripping off the resist from the chromium film using an etchant containing nitric acid. A second method for etching a chromium film comprises the steps of forming an aluminum film or an aluminum alloy film on the chromium film formed on a substrate, forming a resist having a predetermined pattern on the aluminum film or the aluminum alloy film, etching the aluminum film or the aluminum alloy film and the chromium film using phosphoric acid, and removing by etching the aluminum film or the aluminum alloy film using phosphoric acid containing nitric acid after removing the resist.

Abstract: A method is provided for forming a circuit board which comprises a copper plate and an insulating layer of photosensitive polyimide resin formed on the copper plate, the insulating layer leaving an exposed portion of a surface of the copper plate where an LSI is to be mounted. After Au plating is applied to the exposed surface of the copper plate, the LSI is mounted fixedly. A connection pattern having bonding pads is formed by copper plating on the insulating layer. The bonding pads and the LSI are connected by Au wire bonding on the Au plating applied on the bonding pads.

Abstract: A drill bit is provided with a pair of cutting edges which are positioned so that a narrow slot is formed therebetween in an area including the rotational axis of the drill bit and so that the lines joining the rotational axis of the drill bit and the innermost points of the respective cutting edges are at an angle not larger than about 160.degree. with each other as viewed in the axial direction of the drill bit.

Abstract: In manufacturing a composite having a conductive layer on the surface of a resin layer, the first resin layer of polyimide is formed on a substrate of alumina ceramic and, after a resin layer is thermally set by heating, a second resin layer of polyimide is then formed on the first resin layer and is dried. Then the surface of the second resin layer is subjected to selective photoetching by using a photomask having predetermined small opaque areas distributed, thereby to form unevenness including concaves formed as a result of the selective photoetching. The layered composite thus obtained is then heated so that the second resin layer is thermally set. Then catalyst nuclei are formed for electroless plating on the etched surface having the unevenness formed and then a conductive metallic layer is formed by an electroless plating process on the etched surface having the unevenness formed. As a result, a composite of the above described structure is provided.