KR19980020728A - Lead frame for semiconductor chip package with heat dissipation lead - Google Patents

Abstract

A square die pad, a plurality of tie bars connected to an edge of the die pad and integrally formed with the die pad, and having a predetermined portion bent, and arranged to be spaced apart from the die pad by a predetermined distance; And a dam bar integrally formed with the leads in a direction perpendicular to the leads, and a plurality of heat dissipation leads connected integrally with the die pad and having a predetermined portion bent. By providing a lead frame for a semiconductor chip package having a heat dissipation lead in the portion where the die pad is connected to the heat dissipation lead has a groove connected to the side of each of the heat dissipation lead in the inward direction of the die pad , Easy to secure plating area formed on heat dissipation lead It is increasing an effect of improving the reliability of the semiconductor chip package.

Description

Lead frame for semiconductor chip package with heat dissipation lead

The present invention relates to a lead frame for a semiconductor chip package, and more particularly, to a lead frame for a semiconductor chip package having a heat dissipation lead that serves as a heatsink for heat dissipation.

It is important to solve the thermal problem in the structure of the semiconductor chip package. This is because heat generated by the electrical operation of the semiconductor chip generates various problems. For example, heat generated in the package may generate voids or package cracks at the junction interface portion between the semiconductor chip and the die pad. In particular, due to the multi-function, large capacity and high integration of the semiconductor chip package, it can be said that solving the thermal problem is more important. In order to solve this thermal problem, various types of semiconductor chip packages have been developed. One example is shown below.

1 is a plan view of a lead frame having heat dissipation leads according to the prior art.

Referring to FIG. 1, a rectangular die pad 62 is formed at the center of the lead frame 60. On the two transverse sides of the die pad 62, the edge portion of the lead frame 60 facing each side is the side rail 64. The die pad 62 is supported by a tie bar 66 having one side connected to the side rail 64 and the other side connected to the die pad 62. The heat dissipation lead 68 is connected to two sides of the die pad 62 in a direction perpendicular to the tie bar 66. The leads 70 are spaced apart from the die pad 62 by a predetermined distance around the die pad 62. A dam bar 72 integral with the leads 70 is formed between the leads 70 in a direction perpendicular to the leads 70. The outer hidden line in FIG. 1 is a bag boundary. An inner side of the encapsulation boundary line is a region in which a semiconductor chip (not shown) is mounted and is sealed with an epoxy molding resin after wire bonding is completed. The inner hidden line is a region where the lead 70 portion located inside the hidden line as a plating boundary can be plated to improve the reliability of wire bonding. In addition, portions of the lead 70 and the heat dissipation lead 68 outside the encapsulation boundary are bent in a predetermined form after the sealing process. The heat dissipation lead 68 is exposed to the outside and becomes a path of heat dissipation.

FIG. 2 is a plan view illustrating a heat dissipation lead and a die pad of FIG. 1, and FIG. 3 is a side cross-sectional view of FIG. 2.

2 and 3, the die pad 62 is a die for smoothing the loop formation of the bonding wire 84 electrically connecting the bonding pad 82 and the lead 70 of the semiconductor chip 80. Downwards from the position of the lead 70 of the lead frame 60 through the bending of the tie bar 66 connected to the pad 62. At this time, the heat dissipation lead 68 is also bent downward with the tie bar 66. The heat dissipation lead 68 is wire-bonded with the ground terminal of the semiconductor chip 80 in addition to the heat dissipation function to be used as the ground lead. On the outside of the curved point of the heat dissipation lead 68, a bonding portion 74 spot-plated with silver is formed to improve the bonding property when the wire bonding proceeds. The bonding portion 74, which is spot plating, is located inside the package encapsulation boundary.

In the lead frame having the above-described heat dissipation lead, the heat dissipation lead is connected to the die pad and finally exposed to air, thereby obtaining the effect of heat dissipation or heat dissipation. Therefore, not only the occurrence of problems due to heat inside the package can be prevented, but also the wire can be used as a ground terminal by wire bonding the ground electrode of the semiconductor chip to the heat dissipation lead.

However, the lead frame having the heat dissipation lead according to the prior art should ensure the size of the die pad and the die pad should be downset. However, the side of the die pad and the connection part of the heat dissipation lead are rounded due to the limitation of the punching means, so when the downset of the die pad is performed, the predetermined point of the heat dissipation lead is not bent, It becomes curved. Therefore, the plating area between the downset point and the package encapsulation line is reduced, making it difficult to secure the plating area for wire bonding.

Accordingly, an object of the present invention is to increase the plating area in which the plated portions for wire bonding can be located in a lead frame for a semiconductor chip package having heat dissipation leads connected to a die pad and dissipating or dissipating heat. At the same time, it is to provide a lead frame for a semiconductor chip package having heat dissipation leads that can enhance the adhesion of the encapsulant to improve the reliability of the semiconductor chip package.

1 is a plan view of a lead frame having heat dissipation leads according to the prior art;

FIG. 2 is a plan view illustrating a heat dissipation lead and a die pad of FIG. 1. FIG.

3 is a side cross-sectional view of FIG.

Figure 4 is a plan view showing a lead frame having a heat dissipation lead according to the present invention.

5 is an enlarged perspective view of a portion in which the die pad and the heat dissipation lead of FIG. 4 are connected;

6 is a schematic diagram showing a state in which a semiconductor chip is mounted as part A of FIG.

* Description of the symbols for the symbols of the main parts of the drawings *

10,60: lead frame 12,62: die pad

14,64: side rail 16,66: tie bar

18,68: heat dissipation lead 20,70: lead

22,72 Dambar 24,74 Bonding part

26 groove 30 semiconductor chip

The lead frame for a semiconductor chip package having a heat dissipation lead according to the present invention for achieving the above object is a square die pad, connected to the edge of the die pad and integrally formed with the die pad, and a predetermined portion is bent A plurality of tie bars, leads arranged to be spaced apart from the die pad by a predetermined distance, and a dam bar integrally formed with the leads in a direction perpendicular to the leads; A lead frame for a semiconductor chip package having a plurality of heat dissipation leads having curved portions, wherein the die pads are connected to the heat dissipation leads, and the side surfaces of the heat dissipation leads inwardly of the die pads. It is characterized by having a groove connected.

Hereinafter, a lead frame for a semiconductor chip package having a heat dissipation lead according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view showing a lead frame having a heat dissipation lead according to the present invention, FIG. 5 is an enlarged perspective view of a portion where the die pad and heat dissipation lead of FIG. 4 are connected, and FIG. 6 is a portion A of FIG. It is a schematic diagram which shows the mounted state.

4, 5, and 6, a die pad 12 is formed at the center of the lead frame 10, and the die pad 12 is connected to two tie bars 16 formed in a longitudinal direction. Supported by. Two heat dissipation leads 18 are connected in the transverse direction of the die pad 12. Two grooves are formed in each of the heat dissipation lead 18 and the die pad 12 in the heat dissipation lead 18 in the inward direction of the die pad 12. These grooves 26 are formed between the edge of the die pad 12 and the boundary line on which the semiconductor chip 30 is mounted. The heat dissipation lead 18 is bent downward at the edge of the die pad 12 connected to the heat dissipation leads 18 so that the die pad 12 is downset. The bonding part 24 is formed in the upper surface of the heat dissipation lead 18 by silver spot plating.

In the lead frame 10, the bent portion of the heat dissipation lead 18 is moved from the conventional a line to the b line. The curved portion of the heat dissipation lead 18 for the downset of the die pad 12 is located inward toward the die pad 12 by d, so that the area where the bonding portion 24 for wire bonding can be located is The size may extend from the encapsulation boundary (outer hidden line in Fig. 6) to the line a and from the encapsulation boundary (outer hidden line in Fig. 6) to the b line. At this time, the bent portion of the heat dissipation lead 18 is located outside the region where the semiconductor chip 30 is mounted, that is, the bent portion of the heat dissipation lead 18 is located outside the semiconductor chip 30. The width, length and shape of the grooves 26 may be modified within the range made.

According to the structure of the present invention, as well as the increase of the plating possible area for wire bonding to the heat dissipation lead as well as the bar material such as epoxy molding resin when sealing by the grooves formed in the connection portion of the die pad and the heat dissipation lead The contact area is increased.

In the exemplary embodiment of the lead frame according to the present invention, the heat dissipation lead connected to the die pad has been described as two, but the modification may be carried out without departing from the technical spirit of the present invention.

Therefore, according to the structure of the present invention, the bent portion for the downset of the heat dissipation lead is closer to the die pad than the conventional state, the plating area for the wire bonding formed on the heat dissipation lead is increased to increase the wire It is easy to secure a bonding part for bonding, and the adhesive force between the lead frame and the epoxy molding resin is increased due to an increase in the area in contact with the encapsulant, thereby improving the reliability of the semiconductor chip package.

Claims (4)

A square die pad, a plurality of tie bars connected to an edge of the die pad and integrally formed with the die pad, and having a predetermined portion bent, and arranged to be spaced apart from the die pad by a predetermined distance; And a dam bar integrally formed with the leads in a direction perpendicular to the leads, and a plurality of heat dissipation leads connected integrally with the die pad and having a predetermined portion bent. And a groove connected to a side surface of each of the heat dissipation leads in an inward direction of the die pad in a portion where the die pad is connected to the heat dissipation lead. The lead frame for a semiconductor chip package having heat dissipation leads according to claim 1, wherein the tie bars are two and the heat dissipation leads are two. The semiconductor chip package lead according to claim 1, wherein the groove of the die pad is positioned between the outermost line of the mounting area of the semiconductor chip from an edge of the die pad. frame. The lead frame for a semiconductor chip package having heat dissipation leads according to claim 1, wherein the heat dissipation leads have curved portions inside the edges of the die pads.