JPH05136321A - Lead frame and semiconductor device using same - Google Patents

Abstract

PURPOSE:To make the close contact property of the title lead frame with a sealing resin good by a method wherein a through hole is made in a die pad in a semiconductor-chip mounting region; it is covered with a second pad and a semiconductor chip is mounted on it. CONSTITUTION:A die pad is formed of a two-layer structure composed of the following: a first pad 11a provided with a through hole in a region including a semiconductor-chip mounting region; and a second pad 11b composed of an insulating film which is pasted on its upper layer in such a way that the through hole H in the semiconductor-chip mounting region is covered. A semiconductor chip is mounted on the surface of the second die pad 11b of the die pad; it is sealed with a resin. Consequently, the second die pad 11b is used as the semiconductor-chip mounting region. As a result, in a resin sealing operation, the resin is filled into the through hole H and hardened. Thereby, the close contact property of the title lead frame with the sealing resin is made good.

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 enhancement of adhesion of a resin-sealed semiconductor device to a sealing resin.

[0002]

2. Description of the Related Art A lead frame used for mounting a semiconductor device such as an IC and an LSI has a plate-like body made of a metal material such as an iron-based material or a copper-based material, which is formed into a desired pattern by pressing or etching. It is formed by molding.

Usually, the lead frame 1 is, as shown in FIG. 4, a die pad 11 on which a semiconductor integrated circuit chip (hereinafter referred to as a semiconductor chip) is mounted, and a plurality of inner reels arranged so as to surround the die pad. The tie bar 13 that integrally connects the inner lead 12 and the inner lead 12, the outer lead 14 that is connected to each inner lead and extends outside the tie bar, and the tie bar 13 It is composed of side bars 15 and 16 which are supported from the side, and a support bar 17 which supports the die pad 11.

A semiconductor device mounted by using such a lead frame is as shown in FIG. 5, in which the semiconductor chip 2 is mounted on the die pad 11 of the lead frame 1, and this semiconductor chip is mounted. Of the lead frame and the inner lead 12 of the lead frame are connected by a bonding wire 3 of a gold wire or an aluminum wire, which is further sealed with a sealing material 4 such as resin or ceramic, and then the tie bar. -The side bar is cut and the outer lead is bent into the desired shape to complete.

[0005] In recent years, with the increase in size of semiconductor devices, the size of the die pad that supports them has also increased.

Therefore, the pad occupancy rate in the resin encapsulation area becomes large, and the thickness of the resin in the package area tends to be thin, and cracks are generated due to the difference in thermal expansion coefficient between the encapsulation resin and the die pad. It is easy to do so, and this has been a cause of deterioration in reliability of the semiconductor device.

Conventionally, as a measure for preventing such cracks, the back surface of the die pad is subjected to so-called dimple processing for forming small holes or recesses by punching or etching, and resin is poured into these small holes or recesses. A method of reliably fixing the resin on the back surface of the die pad is used.

However, in this method, since the surface of the die pad is affected, it is not possible to perform deep processing, and it is difficult to obtain a sufficient effect.

Further, when the through hole is formed, the conductor paste or solder for mounting the chip may flow out to the back surface, which may cause a short circuit.

[0010]

As described above, the method of performing dimple processing on the back surface of the die pad in order to improve the adhesion with the encapsulating resin at the time of high integration has an influence on the surface of the die pad. However, adjustment was extremely difficult, and a sufficient effect could not be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable semiconductor device which has high adhesion to a sealing resin when highly integrated.

[0012]

Therefore, in the lead frame of the present invention, the die pad is composed of a first pad having a through hole in a region including a semiconductor chip mounting region, and the through pad on at least the semiconductor chip mounting region in the upper layer. It has a two-layer structure with a second pad made of an insulating film attached so as to cover the hole.

Further, in the semiconductor device of the present invention, a first pad having a through hole in a region including a semiconductor chip mounting region, and an upper layer attached to cover at least the through hole in the semiconductor chip mounting region. A semiconductor chip is mounted on the second pad surface of the die pad having a two-layer structure with the second pad made of an insulating film, and the die pad is sealed with resin.

[0014]

According to the above structure, the second pad made of the insulating film laminated on the die pad having the through hole serves as the semiconductor chip mounting area. Since it is filled and cured, the adhesion to the resin becomes extremely good. Since the semiconductor chip is mounted on the second pad, the adhesive does not flow out into the through hole and the surface of the semiconductor chip mounting portion is not affected in any way. Further, the overall thickness can be reduced by a method such as coining the pad having the through hole at the same time as coining the tip of the inner lead so as to reduce the thickness. At this time, since the insulating film is attached, the mechanical strength can be maintained.

Further, since it is sufficient to attach an insulating film to a usual die pad, the manufacturing is easy.

Further, since the through hole is also formed on the back surface of the semiconductor chip mounting area, the adhesion is significantly improved as compared with the case where it is formed outside the semiconductor chip mounting area.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIG. 1, in the lead frame of the embodiment of the present invention, a through hole H is formed in the first die pad 11a including the semiconductor chip mounting area and a second polyimide film is formed on the surface. Die pad 11b
This is characterized in that the resin is attached, and the resin can be poured into the small holes. Other parts have the same structure as that shown in FIG.

Next, a method for manufacturing this lead frame and a method for manufacturing a semiconductor device using the same will be described.

First, as shown in FIG. 2 (a), a band-shaped material is used to press the die in the usual manner. Inner lead 12 and inner
A tie bar 13 that integrally connects the leads 12, an outer lead 14 that is connected to each inner lead and extends outside the tie bar, and a side bar that supports the tie bar 13 from both sides. A lead frame composed of -15 and 16 and a support bar 17 for supporting the die pad 11 is formed. The tip of the inner lead and the first die pad 1
Prior to punching, 1a is thinly formed by coining. Then, the through hole H is also punched at the same time as the punching of the first die pad.

Next, as shown in FIG. 2B, a polyimide film is cut into a shape substantially the same as the first die pad to form a second die pad 11b.

After this, a lead frame is further formed through a plating process or the like, if necessary, and then, as shown in FIG. 2 (c), the first die pad 11a of the lead frame is covered with a polyimide resin layer. 2 die pad 11b
Affix.

Then, the semiconductor device is completed as shown in FIG. 2D through steps such as mounting of the element chip 2, wire bonding, and resin sealing. 3 is a wire and 4 is a resin package.

According to the present invention, when the resin is sealed, the resin is filled in the through holes and hardened, so that the adhesion is extremely good.

Further, due to the presence of the second die pad, the adhesive does not flow out when the semiconductor chip is mounted, there is no fear of affecting the back surface of the first die pad, and the reliability is improved.

In the above embodiment, a large number of circular through holes are formed on the entire surface of the first die pad.
As shown in (a) or (b), long groove type through hole H1
It can be modified as appropriate. As shown in FIG. 3B, since the through holes are formed along the diagonal lines of the die pad, the stress can be easily dispersed.

Further, the second pad may be smaller or larger than the first pad as long as it is formed so as to cover the through hole under the chip mounting area. Also,
It goes without saying that not only two layers but also three or more layers of pads may be formed. Further, according to the present invention, through holes may be formed in areas other than the chip mounting area of the first pad, and these may be exposed from the second pad.

Further, in the above-mentioned embodiment, the through hole is formed by pressing, but it may be formed by etching.

Further, although the first pad is formed thin by coining in the above-mentioned embodiment, it is not always necessary to make it thin.

[0030]

As described above, according to the present invention, a through hole is formed on the back surface of the die pad in the area corresponding to the semiconductor chip mounting area, and the through hole is covered with the second die pad made of an insulating film. Since the semiconductor chip is mounted on this, the resin is also filled in the through holes when the resin is sealed and the resin is hardened, so that a highly reliable and highly reliable semiconductor device can be obtained. It becomes possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a lead frame according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of a semiconductor device using the lead frame.

FIG. 3 is a diagram showing a lead frame according to another embodiment of the present invention.

FIG. 4 is a diagram showing a conventional lead frame.

FIG. 5 is a diagram showing a conventional semiconductor device.

[Explanation of symbols]

 1 Lead Frame 2 Semiconductor Chip 3 Wire 4 Resin Package 11 Die Pad 12 Inner Lead 13 Dam Bar 14 Outer Lead 15 Side Bar 16 Side Bar 17 Support Bar H Through Hole 11a First Die Pad 11b Second Die Pad

Claims (2)

[Claims] 1. A lead frame having a die pad for mounting a semiconductor chip, an inner lead arranged at a predetermined distance from the pad, and an outer lead connected to the inner lead, wherein the die pad Is composed of a first pad having a through hole in a region including a semiconductor chip mounting region and an insulating film attached to the upper layer so as to cover at least the through hole of the semiconductor chip mounting region, the surface of which is A lead frame, comprising: a second pad formed to be a semiconductor chip mounting surface. 2. A second pad comprising a first pad having a through hole in a region including a semiconductor chip mounting region and an insulating film attached to an upper layer of the first pad so as to cover at least the through hole of the semiconductor chip mounting region. A lead frame having a die pad for mounting a semiconductor chip, an inner lead arranged at a predetermined distance from the pad, and an outer lead connected to the inner lead. A semiconductor device, comprising: a semiconductor chip mounted on the second pad; and a sealing resin covering the die pad and the semiconductor chip.