Mitsubishi Denki Kabushiki Kaisha

Yasuhito Suzuki

Akihiro Goto

Yoshiharu Takahashi

Hirokazu Taki

Takashi Arita

Takao Takahashi

Satoshi Ookyuu

Hirochika Kawaguchi

Kazunari Michii

Hiroshi Horibe

Namiki Moriga

Fumiaki Aga

Akira Takaki

A semiconductor device comprises a semiconductor chip. The semiconductor chip has an internal active region, an external active region, and a plurality of electrodes for electrically connecting the internal active region and the external active region to outside thereof, respectively. The semiconductor device also comprises a boarding portion that carries the semiconductor chip, a plurality of external electrode terminals for electrical connection to an external device, a plurality of connecting wires each connecting the electrode of the semiconductor chip and the external electrode terminal; and a mold resin that seals the semiconductor chip, the boarding portion and the connecting wires. The electrodes are disposed around the internal active region, and the external active region is disposed outside the electrodes.

Semiconductor device

To determine leadframe tip positions, a circular arc portion where leadframe tips are to be arranged is determined so as to be opposed to each of the four corners of a die pad by performing a search. Then, straight line portions are set so as to extend from the circular arc portion and to be opposed to the die pad sidelines. The shape of each leadframe tip on the circular arc portion is defined as a region that is sectioned by two concentric circles and two radial rays extending from the center of the concentric circles. The division between the circular arc portion and straight line portions and the setting of the center of the circular arc portion are performed automatically. The leadframe tip width and interval are determined independently of each other.

Designing method of leadframe tip arrangement

First, a reference point on a die pad and a leadframe tip arrangement line are set. A plurality of isosceles triangles having the same base length are set so that their apices are located at the reference point. A given number of isosceles triangles are arranged inside the leadframe tip arrangement line by adjusting the base length. The base length of the isosceles triangles is employed as a uniform lead pitch, and a uniform lead width is then determined. The base length of the isosceles triangles is calculated by using the successive bisection algorithm.

Leadframe tip arrangement designing method

A designing method calculates leadframe tip arrangement. The method comprises the steps of setting a leadframe tip arrangement region opposed to a die pad sideline of a leadframe, setting a leadframe tip arrangement line in the leadframe arrangement region, and arranging a predetermined number of leadframe tips on the leadframe tip arrangement line at proper intervals. The method allows for the independent calculation of various parameters.

A lead frame for semiconductor devices which does not require tie bar cutting in the manufacture of semiconductor devices includes a base lead frame having no tie bars and a dummy lead frame having dummy leads filling gaps between outer lead portions of the leads when the dummy lead frame is mounted on the base lead frame. Instead of tie bars, the dummy leads reinforce the leads and also stop molten sealing resin from flowing into the gaps between the outer lead portions during resin molding.

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Tokyo, Japan

Yasuhito Suzuki