JP3178203B2 - Lead frame for semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a resin-sealed semiconductor device (hereinafter simply referred to as "lead frame").
The present invention particularly relates to the structure of the suspension lead.

[0002]

2. Description of the Related Art First, referring to FIG.
The structure of a lead frame used in a mold resin-sealed semiconductor device (hereinafter simply referred to as “QFP-type IC”) will be described. FIG. 2 is an enlarged plan view of a main part of a conventional lead frame. The lead frame 10 includes a die pad 11 having a quadrangular shape at the center thereof.
A plurality of inner leads 12 along each of the four sides of 1
Are arranged at predetermined intervals, and a plurality of outer leads 13 are connected to each of the inner leads 12. Each inner lead 12 and outer lead 13 are supported by a tie bar 14, and the outer end of each outer lead 13 is connected to a stay 15 or a frame 16.

The tip portion 18 of the suspension lead 17 extending from each corner portion (only one corner portion is shown in FIG. 2) of the die pad 11 is connected to the connection portion 19 of the stay 15 or the frame 16. And is supported and connected to only one location. The tie bar 14, the stay 15, and the frame 16 are collectively referred to as "stay" hereinafter. The hatched portion indicated by reference numeral 20 is a bent portion for depressing the die pad 11 below the tip surface of each inner lead 12.

A semiconductor chip is die-bonded on the die pad 11 of the lead frame 10 having such a structure, and each electrode of the semiconductor chip is connected to the tip of each corresponding inner lead 12 with a gold wire. When the semiconductor chip fixed to the lead frame 10 is sealed with a resin using a molding die for transfer molding, a desired QFP IC is obtained.

[0005]

However, as the area of a semiconductor chip is increased with high density integration, the die pad for mounting such a large semiconductor chip also needs to have a large area. In addition, the number of electrodes and the inner leads are increased, so that the width and pitch of each inner lead are reduced, and the width of the suspension lead is also reduced.

Therefore, when resin sealing is performed using such a lead frame, the die pad receives the fluid pressure due to the molten resin injected into the molding die, and the connection structure of the suspension leads cannot support this fluid pressure. The suspension lead is twisted, and the die pad causes a stay shift. When this stay shift occurs, undesired phenomena such as breaking the balance between the resin above and below the semiconductor chip and cutting the bonded gold wire occur.

[0007]

Therefore, in the lead frame of the present invention, the suspension lead is formed by forming a bent portion on the die pad side and forming the leading end from the die pad side with a substantially constant width. The connecting part on the stay side of the suspension lead is constituted by a central branch lead and a pair of branch leads branched right and left around the center branch lead. The above problem was solved by a structure in which the tip of each branch lead was connected to a tie bar.

[0008]

According to the lead frame of the present invention,
Due to the connection structure of the suspension leads, even if the die pad receives the flow pressure of the molten resin, the suspension leads are less likely to be twisted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a lead frame according to the present invention will be described below with reference to FIG. FIG. 1 is an enlarged plan view of a main part of a lead frame according to the present invention. In FIG. 1, reference numeral 1 indicates the lead frame of the present invention as a whole. The configuration of the other components of the lead frame 1 except for the suspension leads 2 is substantially the same as the configuration of the components of the lead frame 10 of the prior art. The same reference numerals are given and the description of those components is omitted.

In the lead frame 1 of the present invention, the leading end 3 of the suspension lead 2 is divided into a central branch lead 3C and three branch branches 3A and 3B symmetrically diverging symmetrically to the left and right. And the tip of the branch lead 3A is connected to the connecting portion 4A on the extension of the tie bar 14,
The distal end of the branch lead 3B is connected to the connecting portion 4B on the extension of the tie bar 14, and the distal end of the branch lead 3C is connected to the connecting portion 4C of the stay 15 in the same manner as the distal end portion 18 of the suspension lead 17 of the prior art. Formed. It goes without saying that the structure and connection structure of the suspension leads 2 are similarly applied to suspension leads supporting other four corners (not shown) of the die pad 11.

Further, in this embodiment, the distal ends of the branch leads 3A, 3B are connected to outer leads 13A, 13B via tie bars 14, respectively. These outer leads 13A and 13B can be used for a B power terminal and a ground terminal.

Although FIG. 1 shows only one main part of one unit of the lead frame 1 in an enlarged view, the suspension leads for supporting the other four corners of the die pad 11 are similarly constructed. The frame is constituted by a series of lead frames connected by a plurality of units, that is, a frame 16, and is used for manufacturing an IC. This embodiment is a QFP type IC.
However, the present invention can be applied to other types, for example, lead frames for SOP type ICs.

[0013]

As described above, in the lead frame of the present invention, since the leading end of the suspension lead is composed of a plurality of divergent leads, the twist of the suspension lead itself can be suppressed. This configuration makes it difficult to increase the thickness of the suspension lead due to the overall distribution of the inner lead, and is effective even when the length of the suspension lead is increased, and can suppress the twist. Also, by using the branch lead also as another electrode terminal, the number of pins of the IC can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view of a main part of a lead frame for a resin-sealed semiconductor device according to the present invention.

FIG. 2 is an enlarged plan view of a main part of a lead frame for a resin-encapsulated semiconductor device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame of this invention 2 Suspended lead 3 End part of suspended lead 3A Branch lead 3B Branch lead 3C Branch lead 4A Connection part 4B Connection part 4C Connection part 12 Inner lead 13 Outer lead 13A Outer lead 13B Outer lead 14 Tie bar 15 Stay 16 Frame 20 bending part

Claims (1)

(57) [Claims] 1. A die pad, a plurality of inner leads and outer leads arranged at predetermined intervals around the die pad, a tie bar for supporting the inner lead and the outer lead, and a suspension lead for connecting the die pad to a stay. In the lead frame for a semiconductor device composed of, for example, the suspension lead has a bent portion on the die pad side,
The tip side from the die pad side is formed with a substantially constant width, the stay-side connecting portion of the suspension lead is constituted by a central branch lead and a pair of branch leads branched left and right around the center branch lead, A lead frame for a semiconductor device, wherein a tip of the central branch lead is connected to the stay, and a tip of each branch lead branched right and left is connected to a tie bar.