JPH11260986A - Lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lead frame which can be constituted easily and which can resist a high-power use. SOLUTION: A lead frame is provided with a die pad which constitutes a semiconductor package together with a molding resin 7, which is exposed on one face of the molding resin 7 and which is depressed so as to be capable of coming into contact with a mounting board. In this case, the die pad is constituted of a chip mounting part 5 on which a semiconductor chip 2 is mounted and of an exposure part 6 which is depressed from the chip mounting part 5, which is exposed on one face of the molding resin 7 and which can come into contact with the mounting board.

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 mold package used for mounting a semiconductor, and more particularly to a lead frame for obtaining a high power durability.

[0002]

2. Description of the Related Art For example, in a power semiconductor device which consumes high power, a resin mold package (hereinafter abbreviated as a package) having a sufficient heat dissipation so that Joule heat generated by itself does not affect a circuit. Must be used. Therefore, a package including a heat sink has been conventionally used. FIG. 2 shows an example of such a case.
Denotes a semiconductor chip, 7 denotes a mold resin, and 8 denotes a heat sink.

As shown in FIG. 1, the semiconductor chip 2 is mounted on a heat sink 8, and the back surface of the chip mounting portion of the heat sink 8 is exposed from the mold resin 7. Therefore, the heat generated by operating the semiconductor chip 2 and consuming power is:
The heat is transmitted to the heat radiating plate 8 and released to the outside of the package. Since the lead frame 1 and the heat radiating plate 8 are adhered with a non-conductive double-sided tape, there is no electrical continuity between the pins, and there is no hindrance to the operation of the semiconductor.

[0004]

In order to obtain a package having the above-described structure, some processing steps are required in addition to the usual steps of forming a package having no heat sink. For example, in the example of FIG. 2, the formation of the heat sink and the adhesion of the heat sink to the lead frame are indispensable, but this must be performed in a step different from the forming of the lead frame.
Therefore, an increase in the number of processes results in an expensive package, and furthermore, it is necessary to take into account the tolerance of the thickness of the heat sink and the double-sided tape, and the degree of exposure of the heat sink differs in each package. Variations also increase.

In the case of a small package, the heat radiating effect of the heat radiating plate in the package is not so large. Rather, large heat radiation can be obtained by bonding the heat radiating plate to the mounting substrate and using the substrate as the heat radiating plate.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. H8-2135, a configuration has been devised in which the entire die pad is deeply depressed without using a heat sink and the back surface of the die pad is exposed to the package surface. In this case, depending on the size of the semiconductor chip, it is necessary to make the suspension pin an excessive angle. FIG. 3 is a diagram showing this example, and the same or corresponding components as those in FIG. 2 are denoted by the same reference numerals.
In the figure, reference numeral 3 denotes a suspension pin connected to the die pad 5.

However, in such an example, for example,
In the case of a smaller package or a package of a multi-chip type semiconductor device in which a plurality of semiconductor chips are arranged without increasing the package size, it is necessary to minimize the amount of molding resin. In this case, since the hanging pin is depressed, the bending angle becomes steep, which causes a problem that the hanging pin is cut.

An object of the present invention is to provide a lead frame which solves the above problems, can be easily constructed, and does not break the hanging pins.

[0009]

In order to achieve the above object, a lead frame of the present invention constitutes a semiconductor package together with a mold resin, and is depressed so as to be exposed on one surface of the mold resin and contactable with a mounting substrate. In a lead frame provided with a die pad, the die pad includes a chip mounting portion on which a semiconductor chip is mounted, and an exposed portion which is depressed from the chip mounting portion and is exposed on one surface of the molding resin and can contact a mounting substrate. It is characterized by.

Further, the chip mounting portion and the exposed portion of the die pad are connected by a hanging pin, and the exposed portion is depressed by bending and extending the hanging pin.

[0011]

Embodiments of the present invention will be described below with reference to a plurality of examples and drawings. The same or corresponding components are denoted by the same reference symbols throughout the drawings, and description thereof will not be repeated.

FIG. 1 is a view showing an embodiment of the present invention. FIG. 1A is a top view, and FIG. 1B is a sectional view taken along the line AA in FIG. In this figure, 3 is a hanging pin, 5
Numerals 6 and 6 denote die pads serving as a chip mounting portion and an exposed portion, respectively.

As shown in FIG. 1A, the die pad 5
Are connected to the suspension pins 3, and four holes 5 a are formed in a part of the die pad 5 by punching or etching. The suspension pins 4 are provided between the through holes 5a, and the island region surrounded by the through holes 5a is the die pad 6.

As apparent from FIG. 1B, the die pad 5
Is depressed by bending and extending the hanging pins 3, and the die pad 6 is depressed from the position of the die pad 5 by bending and extending the hanging pins 4. The lower surface of the die pad 6 is flush with a substrate contact surface of an external lead formed in a gull wing shape.

Therefore, the semiconductor chip 2 can be mounted on the lead frame 1 as shown by a two-dot chain line in FIG. That is, the die pad 5 can be used as a chip mounting portion, and the die pad 6
Can be an exposed portion exposed so as to be able to contact the mounting board.

With such a structure, the heat generated by the operation of the semiconductor chip 2 is transmitted in all directions, and is also transmitted to the die pad 6 exposed on the package surface. When the die pad 6 and the mounting board are brought into contact with each other by soldering or the like, the mounting board can be used as a heat sink.

Further, since the die pad 5 serving as a chip mounting portion and the die pad 6 serving as an exposed portion are connected by the suspension pins 4, stress is concentrated on the suspension pins at the time of depressing, and the suspension pins are easily deformed, so that they are easily processed. . In addition, since there is a through hole 5a between the hanging pins 4, the through hole 5a is formed during resin molding.
Since the mold resin passes through the mold resin well, the flow of the mold resin is not hindered, and problems such as unfilled resin do not occur.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made.
For example, in the above embodiment, the chip mounting portion and the exposed portion are connected by hanging pins and depressed, but the exposed portion may be protruded by another stepwise depressing method. In a simple example, a die pad which is a single plate is first depressed, and a part of the die pad is depressed to form an exposed portion. However,
As described above, it is needless to say that the configuration in which the connection is made by the hanging pins is advantageous.

In the above-described embodiment, the external lead of the lead frame is a gull-wing type. However, if the exposed portion of the die pad is configured to be in contact with the mounting substrate, the J-lead (Butt-Lead) may be used. J-
Lead).

[0020]

As described above, according to the present invention,
The heat dissipation structure consists only of depressed lead frame,
Since the formation is performed in the same mold, there is no dimensional variation between products as compared with a conventional configuration in which a heat sink is attached.

Further, since the exposed portion exposed on the package surface is formed by further depressing from the depressed die pad and can be brought into contact with the mounting substrate,
The heat in the package can be radiated to the substrate through the die pad. In addition, since the die pad is exposed by performing the depressing stepwise, even a small package or a package having a limited size does not cause a problem that the hanging pins are cut by the deep depressing.

In addition, since the chip mounting portion and the exposed portion of the die pad are connected to each other by the suspension pins, the moldability is improved, so that the depressing is facilitated and the through holes between the suspension pins pass through the resin well. Therefore, a shape suitable for the resin mold can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional lead frame.

FIG. 3 is a sectional view showing another example of a conventional lead frame.

[Explanation of symbols]

 1: Lead frame 2: Semiconductor chip 3, 4: Hanging pin 5: Die pad (chip mounting portion) 5a: Through hole 6: Die pad (exposed portion) 7: Mold resin 8: Heat sink

Claims (2)

[Claims] 1. A lead frame comprising a die package which constitutes a semiconductor package together with a mold resin and is depressed so as to be exposed on one surface of the mold resin and contactable with a mounting substrate, wherein the die pad is a chip mounting part on which a semiconductor chip is mounted. A lead frame, comprising: a part; and an exposed part which is depressed from the chip mounting part, is exposed on one surface of the mold resin, and can contact a mounting substrate. 2. The device according to claim 1, wherein the chip mounting portion and the exposed portion of the die pad are connected by a hanging pin, and the exposed portion is depressed by bending and extending the hanging pin. Lead frame.