JP2001298141A - Resin-sealed semiconductor device - Google Patents

Abstract

(57) [Problem] A small resin-encapsulated type that has a large creepage distance between leads, has little mechanical stress on semiconductor pellets, has excellent heat dissipation, has a small number of components, and can be manufactured at low cost. To provide a semiconductor device. A lower surface of an outer end of a first lead is flush with a lower surface of a resin sealing portion, and a rising portion continuous with the outer end is buried in the resin sealing portion. , The first
The semiconductor pellet 3 is fixed to the inner end 1a of the lead,
The surface of the semiconductor pellet 3 and the inner end 2a of the second lead 2
Is fixed, extends horizontally from the inner end 2a, is deflected downward in a crank shape at a position exposed from the resin sealing portion 4, and the outer end 2b of the second lead 2 is It is formed so as to be flush with the lower surface of the sealing portion 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an improved structure of a resin-sealed semiconductor device that can be surface-mounted on an electronic circuit board or the like.

[0002]

2. Description of the Related Art FIGS. 3 to 6 show examples of a conventional structure of a resin-sealed semiconductor device. The resin-encapsulated semiconductor device shown in FIG. 3 has inner ends 1a, 2a of a strip-shaped first lead 1 and a second lead 2.
a, and solder-fixed so as to sandwich the semiconductor pellet 3 between
The periphery of the semiconductor pellet 3 is sealed with resin so that a part of the outer ends 1b and 2b of the first lead 1 and the second lead is exposed to the outside from the resin sealing portion 4.

As is apparent from the drawing, the lower surface of the outer end 1b from the tip of the outer end 1b of the first lead 1 to the rising portion 1c extending continuously into the resin sealing portion 4 is formed as follows. It is formed so as to be flush with the lower surface of the resin sealing portion 4.
Further, similarly to the first lead 1, the second lead 2
The lower surface of the outer end 2b from the tip of the outer end of the lead 2 to the rising portion 2c is also formed so as to be flush with the lower surface of the resin sealing portion 4.

In the resin-sealed semiconductor device shown in FIG. 4, the inner end 1a of the first lead 1 and the inner end 2a of the second lead 2 in the resin-sealed portion 4 are opposed to each other so as to be on the same plane. And the first
A semiconductor pellet 3 is solder-fixed on the inner end 1a of the lead 1, and a surface electrode (not shown) of the semiconductor pellet 3 is
The inner ends 2 a of the leads 2 are connected by bonding using fine wires 5.

[0005] The resin-encapsulated semiconductor device shown in FIG. 5 has a first lead 1 and a second lead 2 similar to those shown in FIG. 4, but a semiconductor pellet fixed on the inner end 1 a of the first lead 1 by soldering. 3 is connected to the inner end 2a of the second lead 2 by a strip-shaped internal terminal 5 formed of a plate material.

In the resin-encapsulated semiconductor device shown in FIG. 6, a rising portion 1c of a first lead 1 and a rising portion 2c of a similar second lead 2 are bent from the side of the resin sealing portion 4 to the outside. Exposed and the outer end 1b of the first lead 1
And the lower surface of the outer end 2b of the second lead 2 is formed so as to be flush with the lower surface of the resin sealing portion 4.

[0007]

Since the conventional resin-encapsulated semiconductor device is constructed as described above, there are the following problems to be solved. (1) In the resin-encapsulated semiconductor device shown in FIG. 3, the rising portion 1 c of the first lead 1 and the rising portion 2 c of the second lead 2 are embedded in the resin sealing portion 4, so that both leads are used. 1,
It is not applied to a semiconductor device having a small creepage distance L between the two and a large reverse voltage. That is, for example, this type of resin-sealed semiconductor device having a diode structure has been further downsized in order to respond to demands for downsizing and high-density mounting of electronic circuit boards, and the outer shape has been reduced in the length direction. Is about 4 mm. Therefore, the above-mentioned creepage distance L is also relatively extremely small, and how to increase the creepage distance in order to obtain a reverse withstand voltage of 400 V or more has become an issue in the demand for miniaturization.

(2) In the resin-encapsulated semiconductor device shown in FIG. 4, since the surface of the semiconductor pellet 3 and the inner end 2a of the second lead 2 are bonded by the fine wire 5,
There is a problem to be solved in that heat radiation from the upper surface of the semiconductor pellet 3 is poor, and the current that can flow through the semiconductor pellet 3 cannot be increased.

(3) The resin-encapsulated semiconductor device shown in FIG. 5 uses strip-shaped internal terminals 5 formed of a plate material as compared with the structure shown in FIG. However, there is a problem to be solved in that the number of components increases and the number of soldering operations for the internal terminals increases, thereby increasing the manufacturing cost.

(4) In the resin-encapsulated semiconductor device shown in FIG. 6, the first and second leads 1 and 2 exposed to the outside from the side surface of the resin encapsulation 4 are formed on the semiconductor pellet 3 at the time of forming. There is a problem to be solved that a mechanical stress may be applied to deteriorate the electrical characteristics of the semiconductor device.

(5) In the resin-encapsulated semiconductor device shown in FIGS. 3 to 6, the outer end 1b of the first lead 1 and the outer end 2b of the second lead 2 exposed to the outside from the resin-sealed portion 4. Is
Both have target shapes, and for example, in the case of a diode structure, it is necessary to provide a marking for distinguishing which side is an anode or a cathode, which requires labor and cost to solve. was there.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a reduced number of parts, a good heat dissipation, a large current flow, and a large creepage distance.
It is an object of the present invention to provide a resin-encapsulated semiconductor device that has a high reverse voltage, prevents lead deterioration of electrical characteristics, reduces manufacturing costs, and can be manufactured at low cost, using only one lead for lead forming. It is assumed that.

[0013]

In a resin-encapsulated semiconductor device according to the present invention, a semiconductor pellet is fixed between opposing surfaces of inner ends of a first lead and a second lead, and the semiconductor pellet and the inner end are fixed. In a semiconductor device in which the periphery of is sealed with a resin to form a resin-sealed portion, the lower surface of the outer end of the first lead is flush with the lower surface of the resin-sealed portion. A continuous rising portion is buried in the resin sealing portion, and an inner end continuous with the rising portion of the first lead is fixed to the semiconductor pellet, and a surface of the semiconductor pellet and an inner side of the second lead. The second lead is flattened at the outer end of the second lead at a position exposed from the resin sealing portion. Is formed so as to be flush with the lower surface of the resin sealing portion. It is an.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of a resin-encapsulated semiconductor device of the present invention. In this figure, the resin-encapsulated semiconductor device has a first lead 1,
A part of the outer end 1b is exposed to the outside from the side surface of the resin sealing portion 4 as in the conventional case.

A rising portion 1c and an inner end 1a extending continuously from an outer end 1b of the first lead 1 are embedded in a resin sealing portion 4, and a semiconductor pellet is provided on the upper surface of the inner end 1a. 3
Are fixed by soldering. The lower surface from the tip of the outer end 1b to the rising portion 1c is exposed to the outside so as to be flush with the lower surface of the resin sealing portion 4.

A surface electrode (not shown) on the upper surface of the semiconductor pellet 3 and an inner end 2a of the second lead 2 are fixed by soldering. That is, the inner end 2a is formed with a projection 2d formed by stamping or the like by a press or the like, and the projection 2d is fixed to the upper surface of the semiconductor pellet 3 by soldering.

A rising portion 2c formed continuously with the inner end 2a (when viewed from the lower surface of the sealing resin portion 4).
Is exposed to the outside from the resin sealing portion 4 so that the lower surface of the outer end 2b bent and formed in a crank shape continuously with the rising portion 2c is flush with the lower surface of the resin sealing portion 4. Is formed. The forming process of the rising portion 2c and the outer end 2b of the second lead 2 may be performed after the resin sealing step for forming the resin sealing portion 4 is completed. Alternatively, a forming process may be performed in advance before fixing the semiconductor pellet 3 to the solder.

FIG. 2 is a perspective view illustrating a lead frame and the like used in the resin-sealed semiconductor device of the present invention. The lead frame 6 has connecting portions 1d and 2f which are arranged in the longitudinal direction and are opposed to each other. I have.

The first lead 1 is previously formed by a press or the like so that an inner end 1a is formed via a rising portion 1c, and a concave portion is formed on the inner end 2a of the second lead 2 by stamping. 2e (a convex portion 2d on the lower surface side) is formed. Although illustration is omitted between the first leads 1 or between the second leads 2, a tie bar may be provided as needed for reinforcement or the like. Also, the side of the second lead 2 may be formed in advance to form the rising portion 2c and the outer end 2b which becomes a flat surface shown in FIG.

The semiconductor pellet 3 is placed on the inner end 1a of the first lead 1 and the inner end 2a of the second lead 2 still having the connecting portion 2f is superimposed on the upper surface of the semiconductor pellet 3. The pellet 3 is fixed by soldering. That is, the protrusion 2d formed at the inner end 2a is connected to the semiconductor pellet 3
And soldered to the surface electrode (not shown).

The above-mentioned lead frame 6 is housed in a mold (not shown), and a sealing resin is injected thereinto to form semiconductor pellets 3.
A resin sealing portion 4 as shown in FIG. 1 is formed so as to surround a part of the first lead 1 and the second lead 2.

Then, the connecting portions 1d,
2f is cut off, and when the second lead 2 side has not been formed in advance, a predetermined forming process is performed by a press or the like to complete the resin-sealed semiconductor device of the present invention. Referring to the resin-sealed semiconductor device completed as described above, the rising portion 1c on the first lead 1 side is buried in the resin sealing portion 4 as shown in FIG. Since the rising portion 2c on the second side is formed so as to be exposed to the outside from the side surface of the resin sealing portion 4, the creeping distance L can be widened, and a structure suitable for high withstand voltage can be obtained. This is extremely important in securing a maximum creepage distance in a small semiconductor device having an outer shape of about 4 mm.

[0023]

As described above, according to the present invention, asymmetrical leads are used, one of the rising portions is exposed to the outside without being embedded in the resin sealing portion, and wire bonding is performed. In addition, the structure in which the inner end protrusion of one lead is directly fixed to the semiconductor pellet has the following advantages. (1) The creepage distance between the first and second leads can be increased. In particular, since there is a degree of freedom regarding the formation position of one rising portion that is exposed to the outside from the side surface of the resin sealing portion, the position of the rising portion is formed along the side surface of the resin sealing portion as it is formed with an interval. There is an advantage that the distance can be increased. (2) Even when the forming process is performed, only one lead is required, so that the mechanical stress applied to the semiconductor pellet is small, and the electrical characteristics of the semiconductor device are not adversely affected. (3) Since a lead is directly connected to the semiconductor pellet without using a wire bonding structure for connection between the semiconductor pellet and the lead, heat radiation is excellent. (4) Since the internal terminals formed as separate components are not used, the number of components and the number of assembling steps can be reduced so that the device can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a resin-sealed semiconductor device of the present invention.

FIG. 2 is a perspective view of a lead frame and the like used in the present invention.

FIG. 3 is a longitudinal sectional view showing a structural example of a conventional resin-encapsulated semiconductor device.

FIG. 4 is a longitudinal sectional view showing a structural example of a conventional resin-encapsulated semiconductor device.

FIG. 5 is a longitudinal sectional view showing a structural example of a conventional resin-encapsulated semiconductor device.

FIG. 6 is a longitudinal sectional view showing a structural example of a conventional resin-encapsulated semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st lead 1a inner end 1b outer end 1c rising part 2 2nd lead 2a inner end 2b outer end 2c rising part 2d convex part 2e concave part 3 semiconductor pellet 4 resin sealing part L creepage distance

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masashi Kinashiki 1204 Soya, Hadano-shi, Kanagawa Prefecture, Japan Inter Co., Ltd. ) Inventor Kotaro Sato 1204 Soya, Hadano-shi, Kanagawa Prefecture, Japan Incorporated (72) Inventor Noritaka Sugimoto 1204 Soya, Hadano-shi, Kanagawa Japan Incorporated

Claims (1)

[Claims] 1. A semiconductor pellet is fixed between opposing surfaces of inner ends of a first lead and a second lead, and the periphery of the semiconductor pellet and the inner end are sealed with a resin. In the formed semiconductor device, a lower surface of an outer end of the first lead is flush with a lower surface of the resin sealing portion, and a rising portion continuous with the outer end is embedded in the resin sealing portion; An inner end continuous with the rising portion of the first lead is fixed to the semiconductor pellet, a surface of the semiconductor pellet and an inner end of the second lead are fixed, and an inner end of the second lead is It extends horizontally continuously and is deflected downward in a crank shape at a position exposed from the resin sealing portion, and the flat portion at the outer end of the second lead is flush with the lower surface of the resin sealing portion. A resin-encapsulated composite semiconductor device characterized by being formed as follows.