JPS6274033A - Fiber reinforced metallic molding - Google Patents

Abstract

PURPOSE:To provide the titled metallic molding having a small coefft. of thermal expansion in the face direction of cloth mats consisting of continuous fibers and having excellent conductivity and heat conductivity in the lamination direction by molding the cloth mats in the lamination direction thereof then embedding reinforcing materials consisting of metallic members which can form conductive paths for heat and electricity therein. CONSTITUTION:The cloth mat 2 formed by alternately weaving rovings bundled with many pieces of connecting fibers consisting of carbon fibers having 5-10mum average size is cut to a rectangular shape and the cut mats are laminated to form a fiber layer 5. The metallic members 4 consisting of copper sized 1.0mm are penetrated from projections 4a into the fiber layer 5 to form a reinforcing material to be made into a preform. The preform is put into a metallic mold held at about 800 deg.C and a melt of copper at about 1,300 deg.C is poured into the mold, then >=500kg/cm<2> pressure is exerted to the molten metal to made high-pressure casting. As a result, the fiber reinforced metallic molding 1 satisfactorily bound with the carbon fibers constituting the mats 2 is obtd. The volymetric content of the carbon fibers in the molding 1 is 30%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fiber-reinforced metal molded body, and is particularly effective when used as an electrode material such as a supporting electrode of a semiconductor element.

[Conventional technology]

Conventionally, for example, semiconductor elements and their supporting electrodes have been made of silicon and copper, respectively, so the thermal expansion coefficients of both are 4xlO-b/'c and 17x10-'/l, which is four times that of silicon. As mentioned above, if the semiconductor elements are simply joined by soldering, cracks will occur in the joined solder parts due to thermal shock fatigue due to repeated waste heat of the semiconductor elements, and the electrical conductivity and thermal conductivity will decrease. Heat dissipation was inhibited and this caused damage to semiconductor elements.

On the other hand, JP-A-57-185942 discloses a method using a carbon fiber-reinforced copper-based composite material in which short carbon fibers are dispersed in the body, and a supporting electrode with a small coefficient of thermal expansion. ing.

[Problem that the invention seeks to solve]

However, with the above conventional method, it is not possible to produce fiber-reinforced metal with a sufficiently high fiber content because short carbon fibers resist compressive force during molding and cause a springback phenomenon. Therefore, there was a problem that the coefficient of thermal expansion could not be lowered sufficiently.

[Means for solving problems]

Therefore, in order to solve the above problems, the present invention has developed a fiber layer in which cross mats made of continuous fibers are alternately woven at a substantially constant angle, and a fiber layer that conducts heat and electricity in the lamination direction of the cross mats after molding. This method employs a fiber-reinforced metal molded body made of a reinforcing material made of a metal member capable of forming a path, and a matrix metal filled in the reinforcing material.

[For production]

According to the above means, since the cross mats made of continuous fibers alternately woven at a substantially constant angle are laminated,
In the direction perpendicular to the lamination direction, that is, in the plane direction of the crossmat, the influence of fibers with a small coefficient of thermal expansion is noticeable, and the coefficient of thermal expansion in the plane direction becomes sufficiently small, and a conductive path for heat and electricity is formed after molding. Since the metal member to be obtained is embedded in the reinforcing material in advance, a fiber-reinforced metal molded body with excellent electrical conductivity and thermal conductivity in the lamination direction of the cross mantle can be obtained.

[Example] The present invention will be described in detail below based on an example shown in the drawings. FIG. 1 is a perspective view illustrating the structure of a fiber-reinforced metal molded body 1 of the present invention, in which 2 is a cross mant dispersed in copper 3, which is a matrix metal, and 4 is a thermal and electrical conductor of the present invention. It is a metal member that can form a path. In order to explain these shapes in more detail, the manufacturing method thereof will be explained below based on FIG. 2. FIG. 2 is an exploded perspective view showing a preformed body that serves as a reinforcing material used in manufacturing the fiber-reinforced metal molded body 1 of the present invention, where 5 is a convergence of many continuous fibers made of carbon fibers with an average diameter of 5 to 10μ. It is a fiber layer in which a cross mat 2 made of woven rovings alternately woven at right angles is cut into a rectangular shape and laminated. 4 is a metal member that can form the heat and electricity conduction path of the present invention, and has a thickness of 1.0 mm and a fiber layer. A nail-shaped protrusion 4a made of copper having a length corresponding to the height of the reinforcing metal is welded or fitted onto the copper plate 1-4b at one end, and the other end of the protrusion 4a has a sharp tip. By penetrating the protrusions 4a into the fiber portions 5 of this metal member 4, a reinforcing material of the present invention serving as a preform was formed. Note that the total cross-sectional area of the projections 4a is 10 to 10 times the area of the plate 4b.
It is 20%. If this total cross-sectional area is too large, the cross mat 1 will be deformed when thrusting, and if it is too small, the effect of forming heat and electricity conduction paths, which is the objective of the present invention, will not be achieved.

Next, this preformed body is placed in a mold maintained at about 800°C, molten metal at about 1300°C is poured into it, and the cloth mat 2 is formed by high-pressure casting by immediately applying a pressure of 500 kg/cm or more with a punch. The fiber-reinforced metal molded body 1 is formed by bonding with the carbon fibers with good wettability.The volume content V'' of the carbon fibers in this molded body is 30%.

At this time, the protrusions 4a and plates 4b that penetrated the cross mat 2 are melted and bonded to the copper matrix metal and become part of the matrix, but the shape is not sufficiently maintained because the melting occurs only on the surface. Even after it becomes a fiber-reinforced metal, it forms a conductive path that penetrates the matrix.

Next, we will discuss the effect of the conduction path of the present invention using Crossman 2'.
To explain this along with the fine structure of the laminated fiber-reinforced metal, in such a fiber-reinforced metal, the cross mat 2 is laminated and buried in the matrix metal 3 as shown in Fig. 3, but when considering the cross section, the fiber The roving part (hereinafter referred to as part A) is very dense and hardly conducts heat and electricity.
and part B, which is only a matrix that conducts heat and electricity well, and it is thought that heat and electricity flow through part B in the composite as a whole. However, since the content of carbon fiber in this molded body is quite large, the cloth mat 1 is in close contact with the molded body in a considerable part, and this close contact area has an even higher content of fibers and hardly conducts heat and electricity. Therefore, when the heat and electricity that passed through part B, which is made up of a certain roving, are applied to the next eight parts, which are made up of roving, they must be exposed to this close contact part A, and if there is no conduction path in the thickness direction. , the flow of heat and electricity is greatly inhibited and the resistance becomes large. The conduction path of the present invention can improve the thermal conductivity and electrical conductivity in the lamination direction, which are unique to the reinforcing material in which Rossmant 2 is laminated.

Table 1 shows a comparison between a silicon semiconductor chip 6 and a solder 7 bonded using the fiber-reinforced metal molded body 1 with conductive paths of the present invention formed thereon, as shown in FIG. In the example, 0N-OFF of energization to the semiconductor chip 6
This shows the life of the semiconductor chip when the process is repeated, and the heat dissipation effect by the conduction path extends the life of the semiconductor chip 6.

(Margins below) Tables 1 and 2 show that the fiber-reinforced metal molded body 1 of the present invention was produced using the high-pressure casting method explained in the above example and the well-known diffusion bonding method using a preformed body with the same fiber content. It explains the results of measuring the properties of manufactured products, and it is clear that the high-pressure casting method is superior to the diffusion bonding method in terms of thermal conductivity, electrical conductivity, and interfacial peeling characteristics, and it also improves productivity. It's also expensive. Note that the diffusion bonding method is a method in which a matrix metal is attached to the surface of reinforcing fibers by ion blasting, vacuum deposition, plating, etc., and then the fibers are laminated and compressed to form the reinforcing material.

Furthermore, in the present invention, various metal members 4 that can form a conductive path after molding are possible, such as the fifth metal member 4.
As shown in the figure, even if continuous fibers 8 made of copper are woven into the cloth mat 2 in one or two directions in advance and then laminated, the copper fibers will not form a continuous conductive path vertically. The same effect as the above embodiment can be obtained.

Furthermore, as shown in FIG. 6, copper foils 9 may be alternately interposed between the cross mats 2 to form a preform.

In the above embodiments, copper was used as the matrix metal of the metal member and the fiber-reinforced metal that can form conductive paths, but of course, it is not limited to copper, and metals such as silver with excellent electrical conductivity and thermal conductivity may also be used. The metal member 4 and the matrix metal 2 may be of different types.

Further, in the present invention, the volume content <vr> of the carbon fibers constituting the cloth mat 2 is equal to the thermal expansion coefficient of silicon 4
Vr of 30% or more is preferable to achieve a thermal expansion coefficient in this range because if it is less than 1OxlO-'/℃ compared to IO-''/''C, it has the effect of preventing cracks from forming in the solder layer. However, fiber-reinforced metals with a Vf of 50% or more are difficult to form. Further, in the above embodiments, the cross mats 2 are woven alternately at right angles, but the weave is not limited to right angles.

Further, in the present invention, the cross mat 2 is made of continuous carbon fibers, but it may be made of continuous ceramic fibers such as SiC fibers.

The fiber-reinforced metal molded body 1 of the present invention is suitably used as a support electrode for a semiconductor chip 6, but can also be effectively used as an electrode for a ceramic heater.

〔Effect of the invention〕

As explained above, in the present invention, cross mats made of continuous fibers are laminated, and metal members that can form conductive paths for heat and electricity after molding are embedded in the lamination direction of the cross mats. It is possible to provide a fiber-reinforced metal molded body that has a small coefficient of thermal expansion in the plane direction of the cross mantle and has excellent electrical conductivity and thermal conductivity in the lamination direction.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the structure of the fiber-reinforced metal molded body of the present invention, FIG. 2 is an exploded perspective view illustrating the structure of the preformed body, and FIG. 3 is a perspective view of the fiber-reinforced metal molded body of the present invention. A schematic diagram illustrating the fine line structure. FIG. 4 is a schematic cross-sectional view showing the structure of an applied example in which this molded body is used as a support electrode for a semiconductor chip, and FIGS. 5 and 6 are schematic views illustrating other embodiments of the present invention. 2...Cross mat, 3...Matrix metal, 4
a... Protrusion. Figure 1 Figure 2

Claims (1)

[Claims] A reinforcing material consisting of a fiber layer made by laminating cross mats made of continuous fibers woven alternately at a substantially constant angle, and a metal member that can form a heat and electricity conduction path in the lamination direction of the cross mats after molding. and a matrix metal filled in the reinforcing material.