KR20050027383A - Semiconductor chip package having heat slug - Google Patents

Abstract

A semiconductor chip package is provided to improve heat dissipation effect and to enhance formability by installing a heat slug at a periphery of a semiconductor chip. A semiconductor chip(11) with bonding pads(12) is attached on inner leads(21) of an LOC(Lead On Chip) type lead frame(20). The inner lead and the bonding pad are electrically connected with each other by using bonding wires(31). The semiconductor chip, the inner leads and the bonding wires are encapsulated by using a package body(41). A heat slug(51) is attached on a predetermined lower portion of the inner lead.

Description

Semiconductor chip package having heat slug

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor chip package, and more particularly, to a semiconductor chip package having a heat slug in which a semiconductor chip is mounted and assembled in a lead frame and having improved heat dissipation characteristics due to chip thinning.

Recently, according to the development of the semiconductor industry and the needs of users, electronic devices are becoming smaller and lighter, and semiconductor chip packages, which are the core components of the electronic device, are also becoming smaller and lighter. According to this trend, as a semiconductor chip package using a lead frame, it is advantageous to mount a large semiconductor chip compared to a package by a lead-on-chip (LOC) structure, and the lead height is 1.27 mm or less, which is thin and small thin small outline package (TSOP) Is well known.

1 is a cross-sectional view showing an example of a semiconductor chip package according to the prior art.

Referring to FIG. 1, in the TSOP type semiconductor chip package 700 according to the related art, the adhesive tape 715 may be formed on the inner lead 721 of the LOC type lead frame 720 in which the semiconductor chip 711 does not have a die pad. The semiconductor chip 711 and the inner lead 721 are electrically connected by wire bonding, and the semiconductor chip 721 and the bonding wire 731 and the inner lead 721 are directly attached to each other. It has a structure sealed by the package body 741 formed from the molding resin. The semiconductor chip 711 is a center pad type in which the bonding pads 712 are arranged at the center, and the bonding pads 712 are positioned between the inner leads 721 facing each other. The bonding wires 731 are bonded to the top surfaces of the bonding pads 712 and the inner lead 721, respectively. The outer lead 722 protruding to the outside of the package body 741 is formed in a shape suitable for mounting.

The conventional TSOP type semiconductor chip package uses a LOC type lead frame and a center pad type semiconductor chip, which is advantageous in reducing package size and thickness. However, the conventional TSOP type semiconductor chip package does not have a vertically symmetrical structure and is thin, so that warpage is generated when the thermal stress is continuously applied, thereby causing local cracks in the semiconductor chip. Can be generated. In addition, as the operation speed of the semiconductor chip, which has recently been developed, becomes smaller and its size becomes smaller, the power consumption to be discharged per unit volume is gradually increased, and as the operating temperature increases, the operation speed of the semiconductor chip decreases rapidly. Improvement of heat dissipation characteristics of a conventional TSOP type semiconductor chip package is required.

Accordingly, an object of the present invention is to provide a semiconductor chip package that can effectively dissipate heat generated in a semiconductor chip and prevent damage due to thermal stress due to structural imbalance due to an up-down asymmetrical structure.

In the semiconductor chip package having a heat slug according to the present invention for achieving the above object, a semiconductor chip having a plurality of bonding pads is attached to the inner lead of the LOC type lead frame, and the inner lead and the bonding pad are bonded by a bonding wire. In the semiconductor chip package in which the electrical connection is made and the semiconductor chip, the inner lead and the bonding wire are sealed by the package body, the heat slug is attached to the inner lead so as to be positioned around the semiconductor chip.

In the preferred embodiment of the semiconductor chip package according to the present invention, the heat slug is formed of a flat plate and may be bent as necessary. The thickness of the heat slug is preferably 50 [mu] m smaller than the thickness of the semiconductor chip, and the heat slug is preferably 1 mm away from the package end. In addition, the heat slug is preferably thin in the thickness of the edge portion, that is, the package end direction, and a hole formed in the dimple or the thickness direction may be formed on the heat slug surface. In addition, it is preferable to insulate the heat slug by coating it with an insulating film.

In a preferred embodiment of the semiconductor chip package according to the present invention, the heat slug is in direct contact with the back surface of the semiconductor chip. Preferably, thermally conductive bonding means is used for the attachment of the heat slug. In addition, the heat slug is preferably exposed to the outside of the package to improve the heat dissipation effect, and more preferably, a heat sink is attached to the heat slug exposed to the outside.

In addition, in the semiconductor chip package according to the present invention, the ground terminal and the heat slug of the semiconductor chip or lead frame are electrically connected. In this case, a bonding wire, a solder, or a metal bump may be used for the electrical connection. Meanwhile, the outer lead may be lead molded so that the heat slug is exposed from the package body in a direction opposite to the mounting direction.

Hereinafter, an embodiment of a semiconductor chip package having a heat slug according to the present invention will be described with reference to the accompanying drawings. However, like reference numerals refer to like elements throughout the drawings.

2 is a cross-sectional view showing a first embodiment of a semiconductor chip package according to the present invention.

The semiconductor chip package 10 of the present invention shown in FIG. 2 is basically a TSOP type semiconductor chip package including a LOC type lead frame 20 and a center pad type semiconductor chip 11, and considering heat dissipation characteristics. To have a heat slug 51. The semiconductor chip 11 is attached to the lower surface of the inner lead 21 of the lead frame 20, and the bonding pads 12 are disposed between the inner leads 21 facing each other. One side of the bonding wire 31 is bonded to the bonding pad 12 and the other side is bonded to the upper surface of the inner lead 21 to form an electrical connection. At this time, the bonding wire 31 passes between the inner leads.

The heat slug 51 is attached to the lower surface of the inner lead 21 adjacent to the semiconductor chip 11 outside the semiconductor chip 11. The heat slug 11 is made of a material having excellent thermal conductivity, for example, a metal such as copper, and may have various shapes, but here it has a flat shape. The dimple 53 is formed in the surface of the heat slug 51, and has the hole 55 formed in the thickness direction at the edge.

The thickness of the heat slug 51 is equal to or smaller than the thickness of the semiconductor chip 11. The smaller degree is preferably about 50 µm smaller than the thickness of the semiconductor chip 11. This is to prevent physical interference when the semiconductor chip 11 is attached to the adhesive tape 15 during the die attach process and the wire bonding process, and when the semiconductor chip 11 is fixed during the wire bonding process. . The shape of the heat slug 51 may be integral, and may be divided into two or four in terms of stabilizing the molding process. Even when the heat slug 51 is formed separately, the heat release characteristic value does not change significantly.

The method of attaching the heat slug 51 to the inner lead 21 of the lead frame 20 may be a thermally conductive adhesive means, for example, using an adhesive tape 16 or a liquid adhesive such as silver paste. have. The use of silver paste has the advantage of low cost, but it is advantageous to use the adhesive tape 15 because it must be cured and it is difficult to control the proper amount. In addition, it is difficult to attach the adhesive tape 16 to the entire surface of the heat slug 51. In this case, the heat slug 51 physically touches the inner lead 21 during resin molding or handling, and thus some inner lead. There may be a case of electrically conducting (21). Therefore, it is advantageous in terms of process stability that the heat slug 51 forms an insulating coating on the surface, such as polyimide.

On the other hand, the larger the heat slug 51 is better, but it is preferable that at least about 1 mm away from the end of the package side in order to reduce the possibility of poor reliability, such as popcorn cracks when moisture infiltration.

The semiconductor chip 11, the inner lead 21, the bonding wire 31, and the bonding portions thereof are sealed by a package body 41 formed of an epoxy molding resin to be protected from the external environment, and the heat slug 51 is also packaged. It is sealed by the body 41. Electrical connection with the outside is made by the outer lead 22 which is protruded to the outside of the package body 41 and formed in a form suitable for mounting.

Such a semiconductor chip package of the present invention, the heat generated in the semiconductor chip is conducted to the heat slug excellent in heat conduction, and is discharged to the outside through the lead frame through a relatively large area in a short time. Due to the smaller chip size, the heat dissipation characteristics can be improved by dissipating the entirety instead of only locally dissipating heat.

Incidentally, the thicknesses of the upper and lower molded parts based on the semiconductor chip and the lead frame are similar to each other to prevent molding defects in the molding process and thereby reduce warpage. This means a reduction in thermal stress. Therefore, defects related to reliability such as chip cracks can be reduced. As described above, since the thickness of the upper and lower molded parts is balanced, the moldability may be improved. As a result of analyzing the thermal characteristics according to the presence or absence of heat slug using the thermal characterization program, it was expected to improve the exothermic characteristics of about 5% even in natural convection.

In order to improve moldability and reliability, it is possible to secure more technically stability by forming dimples or holes in the surface of the heat slug. That is, the dimple can be controlled to slow down the molding speed without significantly changing the thickness of the heat slug. In addition, the shape of the heat slug becomes thin at the package end, and the package body formed of the epoxy molding compound by forming a hole may serve to hold the heat slug mechanically, thereby improving reliability.

Meanwhile, the semiconductor chip package according to the present invention is not limited to the above-described embodiments and may be variously modified within a range not departing from the technical spirit of the present invention. Another embodiment of the semiconductor chip package according to the present invention will be described.

3 is a cross-sectional view showing a second embodiment of a semiconductor chip package according to the present invention.

In the semiconductor chip package 110 of the present invention shown in FIG. 3, the thermally conductive adhesive 17 is formed on the bottom surface of the semiconductor chip 11 by the heat-type slug 151 down-set in the bottom of the chip. This is an example having a structure attached to. Since heat generated in the semiconductor chip 11 is directly transferred to the heat slug 151 which is in direct contact, the heat dissipation characteristic effect may be more efficient than the semiconductor chip package 10 of FIG. 2. Unlike the general semiconductor assembly process, the semiconductor chip package 110 requires an additional heat slug attachment process after the die attach process.

4 is a cross-sectional view showing a third embodiment of a semiconductor chip package according to the present invention, Figure 5 is a cross-sectional view showing a state in which a third embodiment of a semiconductor chip package according to the present invention is mounted on a substrate.

In the semiconductor chip package 210 of the present invention shown in FIG. 4, a flat heat-slug 251 down-set at the bottom of the chip is directly attached to the semiconductor chip 11 by a direct thermal conductive adhesive 217. The lower surface of the heat slug 251 is an example in which a structure is exposed to the outside. Since the heat slug 251 is in direct contact with the semiconductor chip 11 and a portion is exposed to the outside of the package, the heat dissipation characteristic is further improved. In the case of the semiconductor chip package 210 as described above, when the exposed portion of the heat slug 251 is in thermal contact with the external substrate 70, the effect may be maximized. Of course, it is advantageous to use a thermal interface material (TIM) 75 to make thermal contact with the outer substrate 70, and under-fill when mounted on the outer substrate 70. ) Is very advantageous in terms of heat dissipation characteristics.

6 is a cross-sectional view showing a fourth embodiment of a semiconductor chip package according to the present invention.

The semiconductor chip package 310 according to the present invention illustrated in FIG. 6 is an embodiment in which the heat slug 351 is applied as a ground plane. Among the inner leads 21, the inner lead of the grounding function and the heat slug 351 are connected to the bonding wires 32 by wire bonding, and the heat slug 251 serves as a ground plate. . Thereby, the effect of noise reduction can be obtained. In order to make a larger ground plane, the exposed heat slug 351 is mounted on the outer substrate 80 with solder 85, where vias 81 are electrically connected to the ground plate 83 of the outer substrate 80. When secured to have a more excellent electrical properties. Here, although the heat slug 351 and the inner lead 21 of the ground terminal are connected by the bonding wire 32, the interconnection may be electrically connected using solder or metal bumps.

7 is a cross-sectional view showing a fifth embodiment of a semiconductor chip package according to the present invention, and FIG. 8 is a cross-sectional view showing a sixth embodiment of a semiconductor chip package according to the present invention.

The semiconductor chip package 410 according to the present invention illustrated in FIG. 7 has the same internal structure as the semiconductor chip package 210 of FIG. 4, but the external lead 422 is different from the internal lead 421 of the lead frame 420. ) Is lead molded so that it can be mounted on the other side. The heat slug 451 attached to the bottom surface of the semiconductor chip 11 is exposed to the outside in a direction opposite to the mounting direction. In addition to the structure of the semiconductor chip package 410 of FIG. 7, the semiconductor chip package 510 of FIG. 8 may include a heat sink (eg, a heat sink) through a heat slug 551 and a heat transfer material 575. A heat sink 590 is attached thereto. An example of a structure in which heat dissipation through convection can be further activated by a heat sink.

Therefore, in the semiconductor chip package having the heat slug according to the present invention, heat slug is mounted around the chip to effectively dissipate heat generated in the semiconductor chip through the lead frame and the heat slug having excellent thermal conductivity. Since the semiconductor chip has a vertically symmetrical structure, the moldability may be improved and defects due to mechanical thermal stress may be prevented.

1 is a cross-sectional view showing an example of a semiconductor chip package according to the prior art,

2 to 8 are cross-sectional views illustrating embodiments of a semiconductor chip package according to the present invention.

Explanation of symbols on the main parts of the drawings

10; Semiconductor chip package

11; Semiconductor chip

12; Bonding pad

15,16; Adhesive tape

20; Leadframe

21; Internal lead

22; External lead

31; Bonding Wire

41; Package body

51; Heat slug

Claims (12)

A semiconductor chip having a plurality of bonding pads is attached to the inner lead of the LOC type lead frame, and the inner lead and the bonding pad are electrically connected by the bonding wire, and the semiconductor chip and the inner lead and the bonding wire are connected by the package body. A sealed semiconductor chip package, wherein the heat slug is attached to an inner lead to be positioned around the semiconductor chip. The semiconductor chip package of claim 1, wherein the heat slug is in the form of a flat plate. The semiconductor chip package of claim 1, wherein the heat slug is 50 μm smaller than a thickness of the semiconductor chip. The semiconductor chip package of claim 1, wherein the heat slug is about 1 mm away from the package end. The semiconductor chip package of claim 1, wherein the heat slug has an edge portion, that is, a portion having a thinner thickness in a package end direction. The semiconductor chip package of claim 1, wherein the heat slug has a dimple formed on a surface thereof.  The semiconductor chip package of claim 1, wherein the heat slug has holes formed in a thickness direction thereof. The semiconductor chip package of claim 1, wherein the heat slug is coated with an insulating coating. The semiconductor chip package of claim 1, wherein the heat slug is in direct contact with a back surface of the semiconductor chip. The semiconductor chip package of claim 1, wherein the heat slug is exposed to the outside of the package. The semiconductor chip package of claim 1, wherein the heat slug has a heat sink attached to an externally exposed heat slug. The semiconductor chip package of claim 1, wherein the heat slug is electrically connected to a ground terminal of the semiconductor chip or lead frame.