JPH06244335A - Resin-sealed semiconductor device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a highly reliable resin-sealed semiconductor device in which chip breakage of a semiconductor chip mounted on a die pad is prevented by performing simple additional processing on the die pad of the lead frame. In a resin-sealed semiconductor device in which a semiconductor chip 1 is mounted on a die pad 2a of a lead frame 2 and a peripheral region of the semiconductor chip 1 is sealed with a resin package 3, a chip mounting portion is mounted on a die pad of the lead frame. Reinforcing portions 2d are formed on the periphery by a convex grooving process to enhance bending rigidity and prevent chip cracks in the semiconductor chip due to thermal and mechanical stress applied to the die pad.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed semiconductor device assembled using a lead frame, and more particularly to a lead frame structure.

[0002]

2. Description of the Related Art First, FIGS. 5 and 6 show a conventional structure of a resin-sealed semiconductor device to which the present invention is applied and a lead frame used for assembling the same. In each drawing, 1 is a semiconductor chip, 2 is a lead frame, 3 is a resin package, 4 is a bonding wire connecting between the semiconductor chip 1 and the external lead 2b, and is a lead frame 2 made of a metal ribbon. Has a flat die pad 2a on which the semiconductor chip 1 is mounted, external leads 2b, and tie bars 2c.

In order to assemble such a semiconductor device, first, the semiconductor chip 1 is mounted on the lead frame 2 at a fixed position of the die pad 2a, and then the wire 4 is bonded between the semiconductor chip 1 and the external lead 2b. The resin package 3 is molded by transfer molding, the semiconductor chip 1 is resin-sealed, and tie bar cutting is performed to complete the resin-sealed semiconductor device of FIG.

[0004]

By the way, with the conventional structure as described above, the following problems often occur during assembly and mounting of the product on the printed wiring board.
That is, in the semiconductor device employing the lead frame 2, a large thermal or mechanical stress is applied to the die pad of the lead frame during the molding process of the resin package 3 or when the product is attached to the printed wiring board by screwing or the like. . For this reason, when the lead frame is thin, the die pad is deformed (curved) due to thermal and mechanical stress, which may cause a large stress on the semiconductor chip mounted on the die pad to cause chip cracking. The occurrence of chip cracks increases as the plate thickness of the lead frame becomes thinner, and this is a major cause of lowering the non-defective product rate of semiconductor devices.

The present invention has been made in view of the above points, and by subjecting the die pad of the lead frame to a simple additional process, the above problems are solved and a highly reliable resin encapsulation that suppresses the occurrence of chip cracks. An object is to provide a static semiconductor device.

[0006]

In order to achieve the above object, in a semiconductor device of the present invention, a reinforcing portion for enhancing bending rigidity is formed around a chip mounting portion with respect to a die pad of a lead frame. . In addition, the reinforcing portion in the above-mentioned configuration encloses the chip mounting portion and performs grooved or convex groove processing on the plate surface of the die pad, or surrounds the chip mounting portion and forms a trapezoidal step on the plate surface of the die pad. Shall be formed.

[0007]

By forming the reinforcing portion on the die pad of the lead frame as described above, the bending rigidity of the die pad is increased and a sufficient resistance acts against the thermal and mechanical bending stress. As a result, the heat generated when molding the resin package or mounting the product on the printed wiring board,
It is possible to prevent the semiconductor chip mounted on the die pad from cracking due to mechanical bending stress.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings of the embodiments, the same members corresponding to FIG. 6 are designated by the same reference numerals. In FIGS. 1A to 1C, with respect to the die pad 2a of the lead frame 2 on which the semiconductor chip 1 is mounted, a reinforcing portion 2d is grooved on the plate surface so as to surround the chip mounting portion and have a convex shape. The bulge is formed by processing (pressing). The reinforcing portion 2d can be formed at the same time when the lead frame 2 is punched by a press. The other structure is the same as that of FIG.

With this structure, the convex reinforcing portion 2d functions as a reinforcing rib so as to increase the rigidity of the die pad 2a against bending. Therefore, it is possible to avoid deformation of the die pad itself due to thermal and mechanical stress, and chip cracking of the semiconductor chip 1 due to deformation of the die pad 2a. 2 and 3 show the application example of FIG. 1 described above, and in the configuration of FIG. 2, a concave groove is formed around the chip mounting portion on the plate surface of the die pad 2a as the reinforcing portion 2d. It has been subjected. Further, in FIG. 3, a trapezoidal stepped process is performed so as to surround the chip mounting portion, and any configuration has the same effect as the structure of FIG.

FIG. 4 shows the relationship between the thickness of the lead frame and the crack occurrence rate of the semiconductor chip. That is, the inventors of the present invention conducted a solder heat resistance test using a resin-sealed semiconductor device having a conventional structure manufactured by changing the plate thickness of a lead frame (die pad) variously, and a resin-sealed semiconductor device having the structure of the present invention, and then tested the resin package. The disassembly state of the semiconductor chip mounted on the die pad was investigated. According to the result, in the conventional structure shown in FIG. 6, the chip crack occurrence rate is high when the lead frame plate thickness is 1 mm or less, whereas in the conventional structure shown in FIG. Was confirmed to be significantly improved.

[0011]

As described above, according to the structure of the present invention, by forming the simple reinforcing portion on the die pad of the lead frame, the resin sealing process of the semiconductor device or the product is screwed onto the printed wiring board. By increasing the bending resistance of the die pad against the thermal and mechanical stress applied when mounting it with a stopper, etc., it is possible to reliably prevent chip cracking of the semiconductor chip mounted on the die pad, which improves the reliability of the resin-sealed semiconductor device. Greatly improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, (a) is a plan view of a lead frame on which a semiconductor chip is mounted, (b),
(C) is the arrow AA, BB in the figure (a), respectively.
Cross section

FIG. 2 is a sectional view of a lead frame showing an application example of FIG.

FIG. 3 is a sectional view of a lead frame showing an application example different from that of FIG.

FIG. 4 is a diagram showing the relationship between the lead frame thickness obtained from the solder heat resistance test results and the chip crack occurrence rate of the semiconductor chip.

FIG. 5 is an external view of a resin-encapsulated semiconductor device to which the present invention is applied.

FIG. 6 is a conventional configuration diagram of a resin-sealed semiconductor device,
(A) is a plan view of a lead frame on which a semiconductor chip is mounted, and (b) is a side view of the same.

[Explanation of symbols]

 1 semiconductor chip 2 lead frame 2a die pad 2b external lead 2c tie bar 2d reinforcing portion 3 resin package

Claims (3)

[Claims] 1. A resin-sealed semiconductor device in which a semiconductor chip is mounted on a die pad of a lead frame, and the peripheral area of the semiconductor chip is resin-sealed. Flexural rigidity is provided around the chip mounting portion with respect to the die pad of the lead frame. A resin-encapsulated semiconductor device, characterized in that a reinforcing portion is formed. 2. The resin-encapsulated semiconductor according to claim 1, wherein, as a reinforcing portion, a concave or convex groove is formed on the plate surface of the die pad surrounding the chip mounting portion. apparatus. 3. The resin-encapsulated semiconductor device according to claim 1, wherein as a reinforcing portion, a trapezoidal step is formed on the plate surface of the die pad surrounding the chip mounting portion.