JPH06268122A - Semiconductor device - Google Patents

Abstract

PURPOSE:To give a semiconductor device a moisture resistance which is not worse than that of a hermetically sealed package and reduce the thermal strain applied to a CCB connecting section and, at the same time, to improve the reliability and reduce the thermal resistance of the CCB connecting section by directly pressing a cooling device with the rear surface of a chip wrapped with a sealing material. CONSTITUTION:The title device is constituted in such a way that a chip 5 containing semiconductor elements is fixed to a wiring board 1 equipped with external connecting terminals and the chip 5 is encapsulated in a sealing material. In addition, the surface of the chip 5 opposite to the fixing side is exposed and a removable cooling device 8 is directly pressed to the exposed surface of the chip 5. For example, the chip 5 is mounted in a flip chip state on the upper surface of a PGA base 1 with balls 4 in between and the peripheral surface of the mounting area of the chip 5 is filled with a cured silicone gel 7. Then the rear surface of a heat radiating fin 8 is directly brought into contact with the exposed surface of the chip 5 on the rear side so that the fin 8 can be pressed by a desired pressure by adjusting nuts 11 and the spring forces of springs 10.

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 a semiconductor package structure having low thermal resistance.

[0002]

2. Description of the Related Art Conventionally, a microchip carrier (MC
C) Structure ultra-small package, pinglit array (PG) with external connection terminals (lead pins)
A chip including a semiconductor element is mounted on a wiring board (base) of type A) through a so-called CCB (C
onrolled Collapse Bondin
g) There is a structure in which flip chip mounting is performed by connection, a cap made of ceramics is attached, and a heat radiation fin is attached to the cap. With this structure, when considering the thermal resistance of the semiconductor package, the heat conduction of the cap must be taken into consideration, and in order to secure low thermal resistance, such as matching the coefficient of linear expansion with the wiring board made of ceramics, etc. It requires a high level of technology, and when the cap is attached, there are various problems such as tilting of the cap or a gap in the hermetic seal between the cap and the wiring board.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the drawbacks of the prior art, and provides a technology that can achieve both high reliability and low thermal resistance in CCB connection and further have various advantages. With the goal.
The above and other objects and novel characteristics of the present invention are
It will be apparent from the description of the present specification and the accompanying drawings.

[0004]

The outline of the representative ones of the inventions disclosed in the present application will be briefly described as follows. In the present invention, without attaching a cap, the back surface of the chip whose periphery is sealed with a sealing agent such as silicone gel is exposed from the sealing portion, and a cooling device such as a heat dissipation fin is directly contacted with the back surface of the chip to remove it from the chip. The heat is dissipated directly through a cooling device such as a heat dissipation fin, while the cooling device such as the heat dissipation fin is removable and the contact pressure thereof is variable.

[0005]

As a result, in the thermal resistance of the semiconductor package, it is not necessary to consider the heat conduction of the cap,
It does not require advanced technology such as matching the coefficient of linear expansion between the ceramic cap and the wiring board made of ceramic to secure low thermal resistance, and the cap may tilt or the hermeticity between the cap and wiring board It is possible to solve various problems such as creating a gap in the seal part, solve the drawbacks of the conventional technology, and protect the surroundings of the chip with a sealing agent such as silicone gel, so it is inferior to the hermetically sealed package. A high level of reliability (moisture resistance) is guaranteed, and the back surface of the chip, which is the path of heat dissipation, is left open, and a cooling device such as a heat dissipation fin is brought into direct contact with this, and the chip directly passes through a cooling device such as a heat dissipation fin. The heat dissipation fins can radiate heat satisfactorily. Due to the contact pressure of the heat dissipation fins, the vertical thermal stress is only compressive force. , The thermal strain applied to the CCB connection part becomes small, the life of the connection part becomes long, and the heat dissipation fin can follow the change of the position of the chip and maintain its optimum positional relationship. It is possible to provide a technique capable of achieving both high reliability and low thermal resistance in CCB connection, such as not lowering heat conduction efficiency in a gap, and having various advantages.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view of a semiconductor device showing an embodiment of the present invention, and FIG. 2 is an external perspective view of the same device. A PGA base (wiring substrate) 1 made of mullite ceramics contains a thick film multilayer wiring (not shown), and a thin film multilayer wiring 2 is provided on the upper surface thereof. Lead pins 3 as external connection terminals are provided upright on the PGA base 1. A chip 5 is flip-chip mounted on the upper surface of the PGA base 1 via a solder ball 4 having a Pb98 / Sn2 ratio. A dam 6 for suppressing the outflow of the silicone gel before curing is provided around the mounting area of the chip 5.
A cured silicone gel 7 is filled inside the dam 6 so as to cover the active area of the chip 5 and all of the solder balls 4. The back side of the chip 5 is exposed to the outside. P
Through holes are formed in the peripheral end of the GA base 1 and the peripheral end of the heat dissipation fin 8 made of metallic copper, and the guide rod 9 is inserted into the through holes. The heat dissipation fin 8 made of metallic copper is
Positioning is performed by the guide rod 9, and the spring 1
Screwed with a screw (nut) 11 through 0,
It is attached to the PGA base 1. The back surface of the heat dissipation fin 8 directly contacts the exposed surface of the back surface of the chip 5. By adjusting the nut 11 for screwing and urging the spring 10, the heat radiation fin 8 is pressed against the back surface of the chip 5 with a desired pressure. The heat dissipation fins 8 may be simply pressed against the chip 5, and the thermal stress in the vertical direction may be only the compressive force.
The thermal strain applied to the connecting portion can be reduced, and the life of the connecting portion can be extended. Moreover, since the heat dissipation fins 8 can follow the change in the position of the chip 5 and maintain an optimum positional relationship with the chip 5, the heat conduction efficiency in the gap between the heat dissipation fins 8 and the chip 5 is reduced. Never. On the other hand, by removing the screwed nut 11, the heat dissipation fin 8 can be removed, and a cooling device such as a heat dissipation fin of another form can be attached. The heat dissipation fin 8 can also serve as a mechanical protection of the chip 5 in addition to the purpose of the heat dissipation function. The chip 5 is made of, for example, a silicon single crystal substrate, a large number of circuit elements are formed in the chip 5 by a well-known technique, and one circuit function is given to the chip 5. A specific example of the circuit element includes, for example, a MOS transistor, and these circuit elements form a circuit function of a logic circuit and a memory, for example. A heat conduction bound or the like may be filled between the heat dissipation fin 8 and the chip 5 for the purpose of improving heat conduction. Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. In the above description, the PG, which is the field of application behind the invention made mainly by the present inventor, is the background.
The case where the invention is applied to the A type semiconductor device has been described, but the invention is not limited to this.

[0007]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. According to the present invention, in the thermal resistance of the semiconductor package, it is not necessary to consider the heat conduction of the cap, and matching of the coefficient of linear expansion between the ceramic cap and the wiring board made of ceramic for ensuring a low thermal resistance. It is possible to solve various problems such as the inclination of the cap or the gap of the hermetic seal between the cap and the wiring board without the need for advanced technology such as At the same time, since the chip is protected by a sealant such as silicone gel, a high level of reliability (moisture resistance) comparable to that of a hermetically sealed package is guaranteed, and the back surface of the chip, which is a heat dissipation path, is open. As a result, a cooling device such as a heat radiation fin is directly contacted with this, and the chip is satisfactorily discharged directly through a cooling device such as a heat radiation fin. Due to the contact pressure of the radiating fin, the thermal stress in the vertical direction is only a compressive force, so that the thermal strain applied to the CCB connecting portion is small, the life of the connecting portion is long, and Since the heat dissipation fin can keep track of the change in the position of the chip and maintain its optimal positional relationship, the heat conduction efficiency does not decrease in the gap between the heat dissipation fin and the chip.
It is possible to provide a technique capable of achieving both high reliability and low thermal resistance in CCB connection and having various advantages.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device showing an embodiment of the present invention.

FIG. 2 is an external perspective view of a semiconductor device showing an embodiment of the present invention.

[Explanation of sign]

 1 ... PGA base, 2 ... Thin film multilayer wiring, 3 ... Lead pin, 4 ... Solder ball, 5 ... LSI chip, 6 ... Dam, 7 ... Silicone gel (sealing) Agent), 8 ... radiating fin, 9 ... guide rod, 10 ... spring, 11 ... nut,

[Procedure amendment]

[Submission date] October 26, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

Claims (2)

[Claims] 1. A chip including a semiconductor element is fixed to a wiring board having external connection terminals, the periphery of the chip is surrounded by a sealant, and the surface of the chip opposite to the fixed side is exposed to the outside. A semiconductor device, which is exposed and is formed by directly contacting a removable cooling device to the exposed surface. 2. A cooling device comprising a heat radiation fin, through holes being provided at the end of the wiring board and at the end of the heat radiation fin, a guide rod being inserted through the through hole, and being screwed through a spring. The semiconductor device according to claim 1, wherein the removable heat dissipation fin is pressed against the chip.