JP2596399B2 - 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 semiconductor device, and more particularly to a resin-sealed semiconductor device manufactured using a lead frame assembly having a ground plane.

[0002]

2. Description of the Related Art In recent years, as the operation of a semiconductor device has been accelerated, it has been required that a package structure for mounting the same does not hinder the operation. That is, a package having lower inductance and lower coupling capacitance is required.

Conventionally, as a semiconductor device having improved electrical characteristics by reducing inductance, for example, Japanese Patent Application Laid-Open No.
No. 46851 is known, and this will be described below with reference to the drawings. FIG. 5 (a)
FIG. 5B is a perspective view for explaining a lead frame constituting member of the conventional semiconductor device, and FIG.
FIG. 3 is a partial cross-sectional view of a semiconductor device using the lead frame shown in FIG.

In this conventional example, first, a lead frame assembly is manufactured as follows. That is, as shown in FIG. 5A, an annular insulating adhesive tape 6, a power-supply metal plane 9, an insulating adhesive tape 6, and the like are provided on the lower surface of a lead frame 10 provided with inner leads 4, outer leads and the like.
And the grounding metal plane 1 are laminated in this order and bonded. Then, the joining tabs 3 formed on the outer peripheral edges of the power supply system metal plane 9 and the ground metal plane 1, respectively.
Are connected to predetermined power supply inner leads and grounding inner leads in the inner leads 4 by means such as welding, respectively, to produce a lead frame assembly.

Next, the semiconductor element 7 is mounted on the grounding metal plane 1, and the electrode terminals on the semiconductor element 7 are connected to the grounding metal plane 1, the power supply metal plane 9 and the inner leads 4 by wires 8. Connecting. Thereafter, the entire structure is sealed with a sealing resin 11 by a transfer molding method, and the outer lead portions are cut and formed.
The fabrication of the semiconductor device shown in FIG.

As a second conventional example aimed at reducing the inductance of the grounding system lead, one disclosed in Japanese Patent Application Laid-Open No. 2-60155 is known, and FIG. Will be explained. FIG. 6 is a plan view showing this conventional semiconductor device. In this conventional example, the grounding system lead 12 is provided at the center of each lead row, and the plate width of the grounding system lead 12 is made wider than that of the other leads, so that the grounding system lead can be formed thicker and shorter. Thus, the inductance was reduced.

[0007]

In the above-described first conventional example, in order to reduce the inductance of the entire grounding path, it is necessary to increase the area of the metal plane having a small inductance as much as possible. However, if the metal plane is simply enlarged, the reliability of the semiconductor device may be reduced, such as the interface between the metal plane and the sealing resin may be easily separated due to thermal stress during solder mounting by a method such as IR reflow. Causes a decline. Therefore, the size of the metal plane cannot be designed to a required size according to the electrical characteristic value, and a satisfactory inductance value may not be obtained.

Also, a second method of forming the ground lead to be thick and short
In the conventional example, when the ground lead is designed to be wide,
Due to restrictions such as the space occupied by other leads being narrowed and the required number of pins being unable to be secured, it is not possible to obtain a ground lead having a sufficient width. In practice, the effect of inductance reduction is about several percent. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide a semiconductor having a ground lead having a sufficiently low inductance without reducing reliability due to thermal stress. To be able to provide the device.

[0010]

According to the present invention, a ground plane (1) on which a semiconductor element (7) is mounted is connected to a ground plane connecting portion (3) protruding from the ground plane body. In the semiconductor device connected to the ground inner lead (5) of the lead frame via the ground plane, a ground plane extending portion (W) between the main body of the ground plane and the ground plane connecting portion is wider than the ground plane connecting portion. A semiconductor device characterized by being connected by 2).

[0011]

The inductance and the resistance are not determined only by the shape of the conductor but are changed by the current distribution inside the conductor. If there is a current concentration in the planar conductor, the inductance will increase beyond the value obtained from its geometry.

FIGS. 4A to 4C are plan views for explaining the effect of the present invention. Here, assuming that the one shown in FIG. 4A is the above-mentioned ground metal plane of the first conventional example, instead of this, FIG.
In the case of using the metal plane (b), the inductance can be reduced by about 50%. However, assuming that the size of the resin mold package does not change,
When such a large-area metal plate is adopted,
It easily peels off from the mold resin due to thermal stress caused by soldering or the like.

In the semiconductor device of the present invention, as shown in FIG. 4C, the size of the metal plane main body is made the same as that of the conventional example shown in FIG. Is connected by the metal plane extension 2 between the joining tab 3 and the metal plate body. According to this structure, the function of the current concentrating portion of the large-area metal plane shown in FIG. 4B can be fulfilled by the wide metal plane extending portion 2, so that the inductance is reduced in the case of the metal plane shown in FIG. Can be approached. According to the simulation, the inductance can be reduced by 40% as compared with the case of the metal plane of FIG.

Thus, peeling of the mold resin is most likely to occur at the four corners of the metal plane. Since the shape of the four corners of the metal plane according to the present invention shown in FIG. 4 (c) is not different from that of FIG. it can.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a plan view of a semiconductor device according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA. However, the illustration of the sealing resin is omitted to make the figure easier to see (in FIG. 1A, the resin sealing line 11a is indicated by a broken line).

In this embodiment, a lead frame including, in order from the bottom, a grounding metal plane 1, an annular insulating adhesive tape 6, an inner lead 4, and a grounding inner lead 5 connected to the grounding metal plane 1. Are stacked,
After bonding, the joining tab 3 is connected to the grounding system inner lead 5 by welding or the like to manufacture a lead frame assembly, and the semiconductor device is assembled using the lead frame assembly.

Here, the shape of the grounding system metal plane 1 is as follows.
It has a metal plane extension 2 extending from a conventional square-based shape (see FIG. 4A) toward a joining tab 3 connected to the grounding inner lead 5. Then, the semiconductor element 7 is mounted on the grounding metal plane 1, and bonding is performed from the grounding electrode terminal on the semiconductor element 7 to the grounding metal plane 1 using the wire 8,
Configure the electrical path for the grounding system. Further, another electrode terminal on the semiconductor element is connected to the inner lead 4 by a wire 8, and thereafter, resin sealing is performed by transfer molding by a standard method.

FIG. 2A is a plan view of a semiconductor device according to a second embodiment of the present invention, and FIG. 2B is a sectional view taken along line AA of FIG. In FIG. 2, the same parts as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the duplicate description will be omitted. In the present embodiment, when manufacturing a lead frame, an insulating adhesive tape 6 is adhered to a predetermined position of a metal plate forming the lead frame, and the lead frame is manufactured by stamping. Then, the lead frame is adhered to the grounding metal plane 1, and the joining tab 3 of the grounding metal plane 1 is bonded to the grounding inner lead to form a lead frame assembly. Subsequent steps are the same as in the first embodiment. According to the present embodiment, the positioning when the lead frame is bonded to the grounding metal plate 1 is facilitated, and the manufacturing process of the lead frame assembly is simplified.

The second embodiment can be modified as follows. Instead of using an adhesive tape, an adhesive is applied by a method such as screen printing to manufacture a lead frame. Adhesive tape or adhesive is applied to the grounding system metal plate side, and the lead frame is adhered to this.

FIG. 3A is a plan view of a semiconductor device according to a third embodiment of the present invention, and FIG. 3B is a sectional view taken along line AA of FIG. Also in FIG. 3, the first type shown in FIG.
The same reference numerals are given to the same parts as those of the embodiment. In the present embodiment, the shape of the main body of the grounding system metal plate has a shape obtained by cutting off four corners from the square of the first and second embodiments. When mounting a semiconductor device by soldering or the like, the parts that are most strongly subjected to thermal stress are the four corners away from the center of the metal plate, from which peeling easily starts. On the other hand, considering the electrical characteristics, almost no current flows in this part, so even if this part is cut off, the inductance does not increase much. Therefore, according to the present embodiment, the resistance to thermal stress can be enhanced as compared with the first and second embodiments without sacrificing the electrical characteristics.

In the above embodiment, the metal plate is used only for the grounding system, but one or more power supply system metal plates can be used together. In this case, it is also desirable to provide a wide metal plane extension extending from the metal plane body toward the connection with the power supply inner lead also in the power supply system metal plate.

[0022]

As described above, according to the present invention, in a semiconductor device using a lead frame having a grounding metal plane, the grounding metal plane is moved toward a junction with a predetermined grounding lead. Since the present invention is provided with a wide extension extending from the main body, the inductance can be significantly reduced. For example, QF
In the case of the P package, the inductance can be reduced by about 40% as compared with the case using a metal plane of a conventional size. And since the effect of this inductance reduction can be realized by using a metal plate whose total area hardly changes from the conventional grounding metal plate,
It is possible to improve the electrical characteristics of the semiconductor device without reducing reliability due to thermal stress at the time of solder mounting or the like.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention, and FIG.
Sectional drawing of the A line.

FIG. 2 is a plan view showing a second embodiment of the present invention, and FIG.
Sectional drawing of the A line.

FIG. 3 is a plan view showing a third embodiment of the present invention, and FIG.
Sectional drawing of the A line.

FIG. 4 is a plan view of a grounding metal plane for explaining the operation of the present invention.

FIG. 5 is a perspective view for explaining a lead frame assembly in a first conventional example and a cross-sectional view of the first conventional example.

FIG. 6 is a plan view of a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grounding metal plane 2 Metal plane extension part 3 Joining tab 4 Inner lead 5 Grounding inner lead 6 Insulating adhesive tape 7 Semiconductor element 8 Wire 9 Power supply metal plate 10 Lead frame 11 Sealing resin 11a Resin sealing line 12 Ground System lead

Claims (5)

(57) [Claims] 1. A semiconductor device in which a ground plane on which a semiconductor element is mounted is connected to a ground inner lead of a lead frame via a ground plane connecting portion protruding from the ground plane main body. A semiconductor device characterized by being connected to a ground plane connecting part by a ground plane extending part wider than the ground plane connecting part. 2. The semiconductor device according to claim 1, wherein the ground plane extension portion is wider on the ground plane main body side, and is gradually narrowed toward the ground plane connection portion. . 3. A power supply plane having a through hole for avoiding a semiconductor element is inserted between the ground plane and a lead frame, and the electrode plane is connected to a power supply plane connecting portion protruding from the power supply plane main body. 2. The semiconductor device according to claim 1, wherein the semiconductor device is connected to a power supply inner lead of the lead frame via the lead frame. 4. The semiconductor device according to claim 3, wherein a body of the power plane and the power plane connecting part are connected by a power plane extending part wider than the power plane connecting part. 5. The semiconductor device according to claim 1, wherein a plane shape of the main body of the ground plane and / or a main body of the power plane is a shape obtained by dropping four corners from a square.