Matsushita Electric Industrial Co., Ltd.

Tomio Wada

Teruhiro Sato

Mikio Kobayashi

Yoshiyuki Hirayama

Single flat metal sheet blank in which thin metallic parts including side frames which are to form side walls, a shield plate and external lead and the like are connected together in a developed state in positional relationships necessary for the assembly of the high-density circuit module. A circuit board is then placed on one side of the shield plate of the flat metal sheet blank. Terminals having pedestals are formed on the shield plate. The terminals are inserted into holes formed in the circuit board and connected to conductors on the circuit board. Then, operations such as severance or bending are effected on selected connecting portions at which the thin metallic parts arranged in developed state are inter-connected, and required processings are executed on the portions to be jointed, whereby the circuit module is completed. According to this production method, a space for receiving circuit components is formed between the circuit board and the shield plate, so that both sides of the circuit board can be used for mounting the circuit components, whereby a high packaging density is attained.

High-density circuit module and method of producing the same

A trimmed resistor is provided which has no directional feature when used and is easily mounted on a printed base board. In the trimmed resistor, there are formed four external electrodes arranged at peripheral portions of a rectangular insulation base plate in a point symmetrical distribution about a center of the insulation base plate, a film-like resistance body connected with all of the external electrodes, and a protective film covering the film-like resistance body. Two electrodes among the above-mentioned four electrodes are used as resistor terminals, and a cut slit for trimming is formed in the resistance body longitudinally or as starting from a side of the electrodes serving as resistor terminals.

Trimmed resistor

A high-density circuit module has a box shaped shielding case made from a plate blank which is bent to provide the shield case. A printed wiring board is placed on the bottom surface portion of the shielding case, and a plurality of electronic components are soldered to conductor lands of the printed wiring board. A plurality of externally connected leads are soldered to connection lands of the printed wiring board. A process for producing the high-density circuit module includes the steps of placing the printed wiring board on the blank, then soldering the electronic components and leads to the printed wiring board and then bending the blank to provide the shielding case. The plurality of externally connected leads are formed from a plurality of leads which are originally integrally connected to the bottom surface portion of the shielding case, by separating the plurality of leads form the bottom surface portion of the shielding case. A high-density circuit module having a small number of parts and a simple structure is easily manufactured.

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Yokohama, Japan

Tomio Wada