JPH073849B2 - Lead frame - Google Patents

Description

The present invention relates to a lead frame used in a semiconductor device, and more particularly to a lead frame with improved quality.

[Conventional technology]

The lead frame is often used for resin-sealing semiconductor element chips.The element chip is mounted on the lead frame, then this is resin-sealed, and then the external leads are cut from the frame portion of the lead frame. It constitutes a semiconductor device. Conventionally, in order to improve the shape retention of a large number of external leads provided in this type of lead frame, and to prevent the resin from flowing out of the external leads during resin sealing. A connecting portion called a diver for connecting these external leads is formed.

For example, as shown in FIG. 2, in the lead frame 11, tie bars 13 are integrally formed between the outer leads 12 so as to connect the plurality of outer leads 12 arranged in parallel to each other. Thus, the positions of the external leads 12 in the juxtaposed direction are maintained, and the package resin 10 for sealing the semiconductor element (not shown) is prevented from flowing out downward in the figure.

The tie bar 13 is cut using the punch 14 after the resin sealing is completed, and each external lead 12 is configured as an independent lead.

[Problems to be solved by the invention]

In the conventional lead frame described above, the tie bar 13 is formed to have substantially the same width dimension as the outer lead 12. Therefore, at the time of cutting the tie bar 13, a punch having a length equal to the length of the tie bar 13, that is, a cutting length equal to the interval between the outer leads 12 is prepared, and the tie bar 13 is cut by a shearing force with high cutting strength using the punch 14. Need to disconnect.

Therefore, if the outer leads 12 are displaced due to deformation such as contraction of the lead frame that occurs after resin sealing,
The position of the tie bar 13 and the outer lead 12 with respect to the punch 14 is displaced, and as a result, when the tie bar 13 is cut, the punch
14 may interfere with the outer lead 12. When such interference occurs, the edge of the outer lead 12 is punched by the punch 14.
It is scraped off by the metal, and a whisker-like cutting burr of metal is generated. This whisker-like burr not only impairs the appearance of the semiconductor device, but also causes the external leads 12 to be short-circuited to each other and causes deterioration of the quality of the semiconductor device.

[Means for solving problems]

The lead frame of the present invention is intended to improve the quality of the semiconductor device by preventing the occurrence of whiskers-like burrs on the external leads when the tie bar is cut.

In the lead frame of the present invention, the tie bar that connects the plurality of outer leads to each other is composed of a plurality of thin bars, and is formed in a substantially X shape between adjacent outer leads to hold each outer lead and prevent the resin from flowing out. It is designed to

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and is a view showing a part thereof particularly in a state where resin sealing is performed using a lead frame.

In the lead frame 1, a semiconductor element chip can be mounted on an element mounting portion (not shown), and a plurality of external leads 2 are arranged side by side around the element mounting portion at a predetermined pitch to form an electrode pad of the element chip. Each external lead 2 is configured to be electrically connected with a metal wire. These external leads 2 are connected to each other by tie bars 3 extending in a direction perpendicular to the external leads 2. The diver 3 has a common piece 3b provided at a central portion thereof, and extends from both sides of the common piece 3b toward the outer leads 2 while expanding the width dimension thereof.
The tie bar 3 as a whole is formed in a substantially X shape. In other words, the external leads 2 adjacent to each other are configured as a triangle having common vertices.

According to the lead frame 1, the element chip is resin-sealed so as to include each tip of the external lead 2 and the package 10 is formed.
Make up. When the tie bar 3 is cut after resin sealing, a punch 4 having a width smaller than the mutual distance between the external leads 2 is used as shown by a broken line in the figure. When a force is applied to the common piece 3b in the plane direction, each bar 3a is thinly formed, so that the tie bar 3 is cut off by being torn off from the outer lead 2 very easily.

Therefore, the punch 4 can effectively cut the tie bar 3 even if the punch 4 is sufficiently smaller than the outer lead interval, and therefore the outer lead 2 is not displaced due to the contraction deformation of the lead frame 1 after the resin sealing. Even if it occurs, the punch 4 does not interfere with the external lead 2. As a result, whiskers-like burrs do not occur on the external leads 2 and the deterioration of the quality of the semiconductor device can be prevented.

Further, in this configuration, since the tie bar 3 is formed in a substantially X shape, the outer lead 2 is deformed or deformed in the width direction and the length direction by the action of the two triangles having the common vertex formed thereby. Positional deformation can be effectively prevented, cutting by the punch 4 described above can be further facilitated, and deterioration of the quality of the semiconductor device can be prevented.

〔The invention's effect〕

As described above, according to the present invention, the tie bar is composed of a plurality of thin bars, and is formed in a substantially X shape between the adjacent external leads to hold each external lead and prevent the resin from flowing out. The tie bar can be cut with a punch having a width dimension smaller than the mutual spacing of the leads, thus avoiding interference between the punch and the external lead to prevent whisker-like burrs from being formed on the external lead, and thus shorting the external lead. It is possible to improve the quality of the semiconductor device such as prevention.

Further, in the present invention, since the tie bar is formed in a substantially X shape between the adjacent outer leads, the tie bar is deformed in the width direction and the length direction by the action of the two triangles having the common vertex. Alternatively, the positional deformation can be effectively prevented, the diver can be more easily cut by the punch, and the deterioration of the quality of the semiconductor device can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of an embodiment of the present invention, and FIG. 2 is a plan view of a part of a conventional lead frame. 1,11… Lead frame, 2,12… External lead, 3,13… Tie bar, 3a… Thin bar, 3b… Common piece, 4,14… Punch, 10…
Resin (package).

Claims (1)

[Claims] 1. A lead frame constructed by connecting a plurality of external leads to each other using a tie bar, the tie bar being used to hold each external lead and prevent the package resin from flowing out. It is composed of a thin bar and is connected to each external lead. This tie bar is formed in a substantially X shape between the adjacent external leads, and is configured as a triangle having a common vertex between the adjacent external leads. Characteristic lead frame.