JP2008171963A - Semiconductor chip cooling structure - Google Patents

Abstract

In a semiconductor package in which a semiconductor chip is sealed with a mold resin, a semiconductor chip cooling structure having a high heat dissipation effect in which a semiconductor package and a cooling mechanism are integrated is provided.
A heat dissipation plate and a heat radiation plate formed of a material having good thermal conductivity are disposed inside the mold resin so that the semiconductor chip is sandwiched between the heat dissipation plate and the printed wiring board. The semiconductor chip cooling structure having a high heat dissipation effect can be realized by dissipating heat from both sides of the semiconductor chip into the printed wiring board through the heat dissipation plate.
[Selection] Figure 1

Description

The present invention relates to a semiconductor chip cooling structure in which a semiconductor chip is sealed with a mold resin, the semiconductor chip can be efficiently cooled, and a cooling mechanism and the semiconductor package are integrated.

In recent years, semiconductor devices have been increased in speed and functionality, and the amount of heat generated by semiconductor chips tends to increase. Due to the above-mentioned tendency, various methods for cooling a semiconductor chip have been proposed. As a main cooling method, a metal heat dissipating fin is fixed to the surface of a semiconductor device mounted on a printed wiring board. A method is used in which heat generated in the semiconductor device is transmitted to the heat dissipating fins to dissipate heat.

Further, as a cooling structure of the semiconductor chip that does not use the heat radiating fins, a heat radiating plate is disposed inside the semiconductor package shown in the cross-sectional view of FIG. 5, the back surface of the semiconductor chip and the heat radiating plate are brought into contact, and the heat radiating plate is interposed. There is also a semiconductor package structure that radiates heat to the outside of the mold by natural air cooling and a semiconductor package structure that dissipates heat in the printed wiring board by connecting the heat sink placed inside the semiconductor package shown in the cross-sectional view of FIG. To do.

JP-A-4-11758

In the case of the conventional technology as described above, in an electronic device using a semiconductor device having a large calorific value, a separate cooling mechanism such as a radiating fin or a heat sink for cooling the semiconductor device is often used. Although the heat radiation performance is certainly improved by using heat radiation fins, etc., the heat radiation fins are often provided with vertically elongated grooves in order to increase the surface area and increase the heat radiation efficiency. However, there is a drawback that it increases in the height direction and becomes an obstacle to downsizing of electronic equipment that is progressing year by year. In addition, since a separate cooling mechanism is provided, it becomes a factor in increasing work processes and costs.

In order to solve such a problem, a structure in which a semiconductor package and a cooling mechanism of Japanese Patent Laid-Open No. 4-11758 are integrated is disclosed, and an umbrella-shaped heat dissipation block is directly attached to the surface of a semiconductor chip, The heat generated on the surface of the semiconductor chip is transmitted to the heat dissipation block and dissipated outside the mold resin. Although it is a structure that does not necessarily require a separate cooling mechanism such as a heat radiating fin, it is a natural air cooling of the cooling block exposed to the outside of the mold resin, and the heat resistance of the air that becomes the heat radiating medium is high, so it dissipates heat. The effect is low.

Further, in the structure in which the heat sink of FIG. 6 is connected to the printed wiring board, heat is transferred from the back surface of the semiconductor chip to the heat sink, so that the heat generated on the circuit surface that is the heat generating portion of the semiconductor chip cannot be directly transferred. It is.

The present invention solves the above-described problems and provides a semiconductor chip cooling structure that efficiently cools a semiconductor chip sealed with a mold resin without using a separate cooling mechanism such as a heat radiating fin.

In order to solve the above-described problems, it is important to transfer heat to a medium with low thermal resistance to dissipate heat. In the case of natural air cooling, air with high thermal resistance serves as a heat dissipation medium, so it is difficult to cool a semiconductor chip that generates a large amount of heat. Moreover, the heat dissipation effect can be improved by transferring heat directly from the heat generating portion of the semiconductor chip. Therefore, in a semiconductor package in which a semiconductor chip is sealed with a mold resin, two heat radiating plates formed of a material having good thermal conductivity are arranged inside the mold resin so as to be in contact with both surfaces of the semiconductor chip, and the two sheets A heat sink is connected to the printed wiring board, that is, the semiconductor chip is sandwiched between two heat sinks, and heat is radiated from both sides of the semiconductor chip through the heat sink into the printed wiring board.

Since the present invention has a structure in which a semiconductor chip is sandwiched between two heat sinks and heat is transferred from both sides of the semiconductor chip, the heat dissipation effect can be improved. Further, since the semiconductor package and the heat radiating plate as a cooling mechanism are integrated, it is not necessary to separately provide a cooling mechanism such as a heat radiating fin or a heat sink.

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 shows a cross-sectional structure diagram of the present invention, which has a structure in which a semiconductor chip 1 is sandwiched between a heat radiating plate A and a heat radiating plate B formed of a material having good thermal conductivity, such as copper. More specifically, the heat sink A is brought into contact with the circuit surface of the semiconductor chip 1 via the insulating sheet 11, and the heat sink B is fixed to the back surface of the semiconductor chip 1 using a die attach material 5 such as silver paste. The structure is such that the circuit surface of the chip 1 is connected to the lead frame 6 through the wire bonding 6 and sealed with a mold resin 4 such as an epoxy resin. Further, for connecting the heat sink A and the heat sink B, a pad 8 is provided on the printed wiring board 10, and the heat sink A and the heat sink B and the pad 8 are connected by soldering by reflow.

The heat sink A and the heat sink B shown in FIG.
In this case, at least two sides having a curved shape very similar to the shape of the lead frame 6 are formed so as to be parallel to the lead frame 6. At this time, the heat dissipation effect is also improved by increasing the surface area of the solder connection portion L of the heat dissipation plate. In addition, when the solder connection portions of the heat sink A and the solder connection portions of the lead frame 6 are different, either the heat sink A or the lead frame 6 is mounted on the printed wiring board 10 when mounted on the printed wiring board 10. Since there is a possibility of floating from the pad 8, it is preferable that the solder connection portion of the heat sink A and the solder connection portion of the lead frame 6 are aligned at the same height. In order to mount the semiconductor chip 1, the heat sink B has a larger area than the semiconductor chip 1, and contacts the entire back surface of the semiconductor chip 1. Further, by applying metal plating with good solderability to the heat sink A and the heat sink B, for example, tin plating, the connection strength between the heat sink A and the heat sink B and the pad 8 formed on the printed wiring board 10 is increased. The heat dissipation effect is improved.

The heat transfer path of the present invention includes a path that passes through the heat sink A and a path that passes through the heat sink B. In the path that passes through the heat sink A, heat generated in the semiconductor chip 1 is transferred to the heat sink A via the insulating sheet 11. There is a path for radiating heat from the heat sink A to the printed circuit board 10. The path passing through the heat sink B has a heat transfer path through which heat generated in the semiconductor chip 1 is transferred to the heat sink B via the die attach material 5 and radiated from the heat sink B to the printed wiring board 10. The heat dissipation effect can be improved by dissipating heat from both sides.

The present invention has a structure in which a semiconductor chip cooling mechanism and a semiconductor package are integrated. In a semiconductor device using the present invention, the semiconductor device is mounted on a printed wiring board 10 so that the semiconductor chip 1 A cooling mechanism is also provided. More specifically, since the heat sink A and the heat sink B serving as the heat dissipation medium of the semiconductor chip 1 can be soldered simultaneously with the mounting of the semiconductor device on the printed wiring board 10, the heat sink A and the heat sink B are separately soldered. There is no need to add a process.

Although FIG. 3 shows an example in which the terminal shape portion of two sides is formed on the heat sink A, as shown in FIG. 4, the heat dissipation effect is further improved by forming four terminal shape portions of the heat sink A. It is possible to plan.

In the above embodiment, the shape of the heat sink A shown in FIG. 3 and FIG. 4 was introduced. However, if the heat sink A is formed to have a terminal shape and connected to the printed circuit board 10, the shape may cover all the mold resin 4. Good.

In addition, soldering was introduced in the connection method between the heat sink and the printed wiring board in Example 1,
If the structure is such that the semiconductor chip is sandwiched between the heat sinks and the heat is dissipated from both sides of the semiconductor chip, the connection with the printed wiring board can be replaced with an adhesive having good thermal conductivity.

1 is a cross-sectional view of a semiconductor chip cooling structure according to Embodiment 1. The perspective view of the heat sink A and the heat sink B. FIG. 1 is an overall perspective view of Example 1 when heat is radiated from two sides. FIG. FIG. 4 is an overall perspective view of the first embodiment when heat is radiated from four sides. Sectional drawing (1) of the conventional semiconductor chip cooling structure. Sectional drawing (2) of the conventional semiconductor chip cooling structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2 ... Heat sink A, 3 ... Heat sink B, 4 ... Mold resin, 5 ... Die attach material, 6 ... Lead frame, 7 ... Wire bonding, 8 ... Pad, 9 ... Solder material, 10 ... Print Wiring board, 11 ... insulating sheet, 12 ... heat sink.

Claims (3)

In a semiconductor package in which a semiconductor chip is sealed with a mold resin, the heat dissipation plate and the printed wiring board are arranged inside the mold resin so that the semiconductor chip is sandwiched between two heat dissipation plates formed of a material having good thermal conductivity. A semiconductor package structure characterized by connecting the two.   A semiconductor package having the structure according to claim 1. A cooling mechanism and a semiconductor package having the structure according to claim 1, wherein the semiconductor chip is sandwiched between heat sinks to dissipate heat from both sides of the semiconductor chip into the printed wiring board through the heat sink. The semiconductor chip cooling structure.

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