KR20010049523A - Carbon-based metal composite board-shaped material and method for producing the same - Google Patents

Abstract

PURPOSE: Provided is a board formed with carbon base metal composite material having a thermal conductivity of 150 w/(m.K) or more, a thermal expansion coefficient of 4 x 10-6/deg.C-12 x 10-6 and elastic modulus in the surface direction of 50 GPa or less and suitable to a substrate for electronic devices. CONSTITUTION: The board formed with carbon based metal composite material is composed of the carbon base metal composite material produced by impregnating aluminum, copper, silver or alloy thereof into a carbon formed body containing graphitized grain or a carbon formed body containing carbon fiber with molten material forging. The producing method of the carbon base metal composite formed board is executed by bringing the carbon formed body into contact with molten aluminum, molten copper, molten silver or molten alloy thereof under pressure to impregnate the molten metal into the carbon formed body.

Description

Carbon-based metal composite plate shaped body and manufacturing method {CARBON-BASED METAL COMPOSITE BOARD-SHAPED MATERIAL AND METHOD FOR PRODUCING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-based metal composite plate shaped body and a method for manufacturing the same. Specifically, the present invention relates to a substrate for an electronic device having a high thermal conductivity, a low thermal expansion rate, and a low elastic modulus made of a composite material of a carbon molded body and aluminum or copper. It is about.

As heat generation increases due to high functionality and high capacity of electronic devices, a material having a low thermal expansion rate and a high thermal conductivity effective for heat removal is required. Most of the heat generated from electronic circuits consisting of semiconductor devices, resistors, transformers, capacitors, or wirings is transmitted to the cooling device from the circuit board or the base board, which is a support of the circuit board, and finally radiates into the atmosphere or cooling liquid. . In an electronic circuit which generates a large amount of heat, aluminum, copper or an alloy thereof having good thermal conductivity is usually used for the base substrate material.

Also, recently, a heat transfer material having a low thermal expansion rate controlled by combining carbon fiber or ceramics with a metal has been proposed (see, for example, Japanese Patent Laid-Open No. 11-97593).

However, aluminum, copper or alloys thereof used in the base substrate material have good thermal conductivity but high thermal expansion rate. On the other hand, electronic circuits made of silicon semiconductor elements or ceramics stacked on a base substrate have a low thermal expansion rate and thus have problems such as bending or peeling due to mutual thermal expansion differences.

As a material for solving the above problems, a substrate made of a ceramic having low thermal expansion coefficient, such as silicon carbide, aluminum, silicon nitride, or a composite material of aluminum nitride, aluminum, and copper metal, has been devised. There is a difficult difficulty.

In addition, as a material for solving the above problems, a composite substrate made of metal tungsten, molybdenum and copper having a low thermal expansion rate has been devised, but these composite substrates have a problem of heavy weight and difficult processing. Further, substrates made of silicon and aluminum alloys have also been proposed, but have not been put to practical use. However, conventionally proposed materials satisfy both thermal conductivity and thermal expansion rate, but a product having good processability has not been realized. In addition, since both materials of the related art also have high modulus of elasticity, when joining materials having different thermal expansion coefficients, a large thermal stress is added to the joint surface, resulting in flaws.

Accordingly, an object of the present invention is an electronic circuit made of silicon elements or ceramics which are light in weight and high in thermal conductivity in view of the development of substrates for electronic devices as described above. It is to provide a substrate for the device.

Accordingly, the present inventors have repeatedly studied intensively in order to achieve the above object, and a binder mixture such as filler and coal tar pitch having high thermal conductivity such as petroleum coke, natural graphite or pitch carbon fiber, etc. The above-mentioned problem can be solved by a plate-shaped molded body made of a carbon-based metal composite material obtained by impregnating a molten alloy of molten aluminum, copper and their metals in a hollow hole of a graphitized carbon molded body at high pressure by molten forging. It has been shown that the present invention is completed based on their knowledge.

That is, the first of the present invention,

A carbon-based metal comprising a carbon-based metal composite material obtained by press-impregnating aluminum, copper, silver, or an alloy of the above metals by molten forging into a carbonaceous body containing graphitized carbon particles or carbon fibers. Composite plate shaped body

It is about.

In addition, the second of the present invention,

It is a manufacturing method of the carbonaceous metal composite material plate-shaped molded object formed by impregnating a molten metal in a carbon molded object by contacting a carbon molded object under pressure and the alloy of molten aluminum, molten copper, molten silver, or these molten metals,

(1) heating the carbon molded body at a temperature equal to or higher than the melting point of the molten metal in an inert atmosphere;

(2) pressurizing and impregnating the heated carbon molded body by molten forging at a pressure of 200 kg / cm ² or more per presser unit area by using a press device,

(3) a step of cooling and solidifying the molten metal after completion of pressure impregnation in step (2),

(4) a step of picking up the carbon molded body from the solidified body obtained in step (3), and

(5) A method for producing a carbonaceous metal composite material plate-shaped molded body comprising the step of molding the metal-impregnated carbon molded body obtained in the step (4) onto a plate.

1 is a schematic view showing the basic structure of the manufacturing apparatus of the present invention.

2 is a schematic view showing another structure of the manufacturing apparatus of the present invention.

3 is a schematic view showing another structure of the manufacturing apparatus of the present invention.

4 is a basic configuration diagram of an electronic device using a carbon-based metal composite substrate.

Hereinafter, the present invention will be described in more detail.

The carbon-based metal composite plate shaped body of the present invention is a carbon-based metal composite material formed of a carbonaceous matrix and a metal component dispersed in the carbonaceous matrix on a plate. The molding method on the carbonaceous metal composite sheet is not particularly limited, but a press molding method or a doctor blade method may be employed, but a method of cutting out from the carbon-based metal composite material is preferred. Although the thickness of a molded object may be arbitrarily determined at the time of shaping | molding so that it may be suitable for a desired use, 0.1 mm-50 mm, especially 0.3 mm-3 mm are preferable in the board | substrate for electronic devices.

Density at room temperature of the carbon-based metal composite sheet molded product of the present invention is from 2.0 g / ml to 2.5 g / ml when impregnated with aluminum or an aluminum alloy, and also when impregnated with copper, silver, copper alloy or silver alloy. The density at room temperature is 2.3 g / ml-5.0 g / ml. The thermal conductivity of the carbon-based metal composite sheet-like molded body is 150 W / (m · K) or more in the thickness direction at room temperature, and preferably 200 W / (m · K) or more. The thermal expansion rate is 4 × 10 ⁻⁶ / ° C. to 12 × 10 ⁻⁶ / ° C., and is preferably controlled to 5 × 10 ^{−6 to} 8 × 10 ⁻⁶ .

In addition, in the carbon-based metal composite sheet molded product of the present invention, a specific elastic modulus, such as the thermal conductivity and thermal expansion coefficient, is provided so that the bidirectional elastic modulus is within a range of 50 GPa or less, and preferably controlled to 3 GPa to 15 GPa. With such controlled growth, the electronic circuit made of a silicon element or ceramics and the base substrate junction are not peeled off, and the thermal cycle test is strong.

The carbon molded body to be used as the carbonaceous matrix constituting the plate-shaped molded body of the carbon-based metal composite material having the above-described properties preferably contains amorphous carbon, graphite carbon or mixtures thereof, and graphite crystals. Graphite-based crystals are measured by X-ray diffraction, and the average plane spacing d is preferably 0.340 nm or less, particularly 0.338 nm or less. As a carbon material, the press-formed body containing at least one carbon material of (a) general carbon material, (b) carbon powder, natural artificial graphite, and carbon fiber is mentioned. It is preferable that the carbon molded body contains heat treated and graphitized carbon particles, and in particular, it is preferable to use petroleum coke of 0.1 mm to 3 mm and natural graphite as a filler with the largest particle diameter constricted. If the maximum particle diameter does not reach 0.1 mm, the thermal conductivity of the molded article does not increase sufficiently. On the other hand, if the maximum particle size exceeds 3 mm, the surface roughness of the substrate surface deteriorates sharply, which makes it difficult to use as a substrate. In addition, the graphite particles as the filler in the carbon molded body are preferably 10% or more by volume, and the pitch-based carbon fiber is 10% or more by volume.

Next, the manufacturing method of the carbon-based metal composite plate-shaped molded object of this invention is demonstrated. The carbon molded product used in the method for producing a carbon-based metal composite sheet molded product of the present invention is preferably a heat treatment of the carbon material at a temperature of 2800 ° C. or higher, particularly at 3000 ° C. or higher, so that the graphite crystal is contained.

Moreover, as a carbon molded object, it is effective to use the molded object which heat-treated the carbon fiber carbon composite material which becomes a filler from petroleum coke and pitch type carbon fiber more than 2800 degreeC, especially 3000 degreeC or more for several hours.

According to the present invention, a composite material obtained by pressurizing and impregnating the molten metal in the carbon molded body by forging the molten metal by contacting the molten metal with a molten metal under pressure under heat treatment at a temperature of 2800 ° C. or more and graphitized. A method for producing a carbon-based metal composite plate-shaped molded body that is formed in a plate shape, the method comprising the steps of (1), (2), (3), (4) and (5). A method is provided.

In other words,

(1) heating the carbon molded body at a temperature equal to or higher than the melting point of the molten metal in an inert atmosphere;

(2) pressurizing and impregnating the molten metal at a pressure of ²⁰⁰ Kg / cm ² or more per presser unit area by using a press apparatus in the carbon molded body heated by supplying the molten metal using a press device;

(3) cooling and solidifying the molten metal after completion of the pressure impregnation in step (2),

(4) a step of taking out the carbon molded product from the coagulated body obtained in step (3), and

(5) The process of shape | molding the metal impregnated carbon impregnated molded object obtained by the process (4) on a plate is mentioned.

The carbon molded body can be used for any of the carbon materials suitable for the electric carbonaceous matrix. Specifically, the preferred carbon molded body density is 14 g / cm ^{3 to 2} g / cm ² and the porosity is 50% or less, preferably 35% or less, and more preferably 5% to 25%.

Next, each process is demonstrated concretely.

In the said process (1), a carbon molded object is installed in a metal mold | die, and is preheated in inert atmosphere. Argon nitrogen gas or the like is preferably used as an inert atmosphere. The preliminary heating is to maintain the melting point or melting point of the metal component, in particular, 100 ° C or more, preferably 100 ° C to 250 ° C. By going through this step (1), it is designed to sufficiently impregnate the metal in the pores of the carbon material while suppressing the reaction at the interface between the carbon and the metal.

Next, in the step (2), the metal component is melted at a temperature 50 ° C. to 250 ° C. higher than the melting point of the metal component, the molten metal is supplied to the mold, and contacted with the preheated carbon molded body to use a press apparatus for the molten metal. Then, a presser impregnated a pressurized impregnated molten metal into the carbon molded body by applying a pressure of 200 kg / cm ² or more per compression area. In the case of aluminum in the step (2), when the molten metal temperature exceeds 150 ° C, deliquescent aluminum carbide is easily produced, and a practical composite material is not obtained. On the other hand, if the pressure does not reach 200 kg / cm ² , impregnation of the metal component is not performed efficiently, which may lower the metal filling rate.

In the method for producing a carbon-based metal composite material of the present invention by molten forging, the molten metal is impregnated with the molten metal when the molten metal is placed in a mold and brought into contact with the carbon molded body placed in the mold to coagulate under high pressure. The apparatus used for forging molten metal consists of a mold with a space inside and a puncher (punch), so that each compression is close to the inner wall surface of the opening of each mold so that it is free to move inward and outward and can be moved inward by pressing. . Examples of the molten metal forging method include an open-mold method shown in FIG. 2, that is, a direct press method and a cross-mold method (indirect press method) shown in FIG. It is preferable to use the open-molding method for the production of the carbon-based metal composite sheet molded product of the. A feature of the metal impregnation method in the method for producing a carbon-based metal composite material of the present invention is that the metal structure becomes dense in order to solidify molten metal in a short time, and a large complex that is difficult as a metal impregnation method by a conventional gas pressurization method. The point is that the material can be easily produced.

After completion of the step (2), the molten metal is cooled in the step (3) to obtain a solidified body.

Next, in the step (4), the solidified body obtained in the step (3) is obtained from the mold and the metal part is cut and melted to obtain a carbon molded product removed from other methods. Through the process of the carbon-based metal composite plate can be obtained. Specifically, since the carbon-based metal composite material has good workability, a plate-shaped molded body can be produced by, for example, cutting into band sow or wire sow.

Specific examples of the apparatus used in the method for producing the carbon-based metal composite material of the present invention are shown in Figs.

1 to 3, (1) denotes a mold, (2) compresses, and (3) illustrates a press machine. The carbon molded body 4 is put in the metal mold 1, and preheating by the said process (1) is carried out in argon gas, and after supplying and compressing the molten metal heated to predetermined temperature (3), it is inside a metal mold. The molten metal is pressed and maintained under the same conditions for a predetermined time. After a predetermined time has elapsed, the metal coagulum is obtained from the mold as a mass of metal, and the metal part can be removed by cutting, melting, or other methods to obtain a metal-impregnated carbon-based metal composite plate-like molded body.

(Formed body on substrate for electronic device)

Next, a substrate-shaped molded article useful as a heat dispersion of an electronic device for the use of the carbon-based metal composite sheet shaped article of the present invention will be described.

In an electronic circuit surrounding a circuit supporting substrate of an electronic circuit composed of a semiconductor element, a resistor, a transformer, a capacitor or a wiring and a base substrate which is a support of the circuit supporting substrate, most of the heat generated from the electronic circuit is generated from the circuit supporting substrate and the base substrate. Heated to the chiller and finally radiated to the atmosphere or cooling liquid. Conventionally, metals made of aluminum, copper, or alloys thereof have been used as the base substrate material, but there is a problem in that there is a difference in thermal expansion between the electronic circuit and peeled off in reverse. Since the carbon-based metal composite material of the present invention has a thermal conductivity of 150 W / (m · K) or more and a thermal expansion coefficient of 4 × 10 ⁻⁶ / ° C. to 12 × 10 ⁻⁶ / ° C., the thermal conductivity is equal to solve the above problem. do. In addition, the bidirectional elastic modulus of the plate-shaped molded product is in the range of 50 GPa or less, and when the materials having different thermal conductivity are joined, the thermal stress applied to the bonding layer can be alleviated. This prevents peeling and also allows for strong thermal cycle bonding.

It is preferable that the plate-shaped carbon molded object for electronic devices of this invention has a density of 2 g / cm <^3> or more. Specifically, the aluminum or aluminum alloy substrate impregnated with a carbon molded body has a density of 2.0g / cm ³ ~2.4g / cm ³ or that of the copper or copper alloy substrate impregnated with a carbon molded article density of 2.3g / cm ³ ~5.0g / cm ³ is suitable.

Fig. 4 shows a specific example of an electronic device including a substrate-shaped carbon molded body made of the carbon-based metal composite material of the present invention used as a heat dispersion of an electronic circuit.

In the figure, the substrate 6 made of the carbon-based metal composite material of the present invention is bonded to the ceramic insulating substrate 7 via the adhesive layer 9. As the adhesive layer, a synthetic resin, a soft solder, a metal solder material and the like are used. Circuits, circuit elements and components 8 are provided on the ceramic insulating substrate 7. A large amount of heat is dissipated from the circuits, the circuit elements, and the components 8 and is transferred to the substrate 6 to radiate heat with a cooling device (not shown) bonded to the lower portion of the substrate 6.

Hereinafter, an Example and a comparative example demonstrate this invention concretely. Furthermore, the present invention is not limited by the examples and the like.

In addition, the following measuring method is used regarding the quality and performance evaluation of the carbon-based metal composite material produced by the Example and the comparative example.

1) density

It measured by the Archimedes method using the electronic analysis balance AEL-200 by Shimadzu Corporation.

2) bending strength

The bending strength was measured with respect to the strength test piece produced using the Shimanzu Corporation precision universal testing machine AG-500. It measured on the conditions of the test piece size 4mm * 4mm * 8mm, the distance between spans 60mm, and the crosshead descent rate 0.5mm / min.

3) thermal conductivity

Thermal conductivity was determined by the product of thermal diffusivity, specific heat and density. The thermal diffusivity was measured at 25 ° C. using TC-7000, a vacuum processing company, by the laser flash method. In addition, a ruby laser light (excitation voltage 2.5 Kv, a uniform filter, and one photosensitive filter) was used as irradiation light.

4) thermal expansion rate

The thermal expansion rate from room temperature to 300 degreeC was measured using the Max Science heat removal analyzer 001, TD-5020.

5) elastic modulus

Stress of strength test Calculation was made from the anaerobic data.

Example 1

Four types of carbon molded bodies of three kinds of artificial graphite materials A, B and C and one kind of carbon fiber and carbon composite material were used. The preform was preheated to 760 ° C in argon gas and installed in a mold preheated to 500 ° C. Pure aluminum melted at 810 ° C. was placed in a mold. It was pressurized by the press machine so that it might become pressure 500Kg / cm <^2> with respect to the pressing surface of a presser by molten metal forging, and it hold | maintained in that state for 30 minutes. After cooling, the mass of aluminum was taken out and cut to obtain a carbon-based metal composite.

TABLE 1

In addition, electroless nickel plating was installed on the 33 mm long, 90 mm wide, and 3 mm thick substrates starting from the graphite material A, and the aluminum substrates were bonded with a high temperature soluble alloy to perform 250 temperature cycle tests at -55 ° C and 150 ° C. But there was no abnormality.

Example 2

Two types of carbon molded bodies of artificial graphite material (for electrodes) were used. Each molded body was preheated to 960 ° C in argon gas and installed in a mold preheated to 600 ° C. 960 degreeC melted seven samsam brass was put in the metal mold | die. The pressing surface of the presser was pressurized to 1000Kg / cm2 and kept in that state for 30 minutes, and the impregnation was mixed with the seventh brass. After cooling, the chunks of the brass were cut and processed to obtain a carbon-based metal composite sheet.

Measurements of thermal conductivity, thermal expansion rate and elastic modulus are shown in Table 2, which satisfies the required growth.

TABLE 2

Comparative Example 1

Table 1 shows the characteristic values (catalog values) of aluminum / silicon carbide composites (Al / SiC) as examples of commercially available products currently used in electronic device substrates. Among them, the modulus of elasticity is different from that of an electronic device substrate using the carbon-based metal composite material of the present invention.

Comparative Example 2

The plate-shaped molded object was obtained after impregnating molten aluminum by the method similar to the method of Example 1 using the carbon molded object which is not graphitized. It was found that the plate-shaped molded body had no cracks due to cracks in an atmosphere of 85 ° C. and a relative humidity of 85% for 24 hours. This is considered to be because aluminum carbide produced | generated easily hydrolyzed when carbon and aluminum react.

The thermal conductivity of the carbon-based metal composite plate-shaped molded product of the present invention is increased by 100 W / (m · K) at most than the carbon molded product before impregnation. In addition, the thermal expansion rate can manufacture a thing of arbitrary numerical value in the range of 4 * 10 <^-6> / degreeC-12 * 10 <^-6> / degreeC by changing the kind or metal species of a carbon molded object. The thermal expansion rate is 3 × 10 ⁻⁶ / ° C. to 4 × 10 ⁻⁶ / ° C., 4.5 × 10 ⁻⁵ / ° C. of aluminum nitride, or 7 × 10 ⁻⁶ / ° C. of aluminum, which is mounted on the same substrate. It is close to -8x10 <^-6> / degreeC. In addition, since the elastic modulus of the substrate is small, the thermal stress on the bonding layer and the same interface can be reduced. Therefore, the use of the substrate of the present invention can suppress the occurrence of defects such as peeling off due to a small thermal stress generated from the thermal expansion difference between the substrate and the mounted electronic device.

In addition, since the carbon-based metal composite sheet-like molded body has an electric structure, the properties of brittle carbon materials can be improved and the substrate for electronic devices having excellent strength is provided. In particular, in mechanical processing, material cracking and crushing do not occur, and processing is easy, and high processing precision can be obtained.

Claims (9)

Pressurized impregnation of aluminum, copper, silver, and alloys of respective metals with a molten metal forging into a carbon molded body containing graphitized carbon particles and carbon fibers. Characterized by consisting of a carbon-based metal composite prepared by Carbon based metal composite plate shaped body. The method of claim 1, The carbon-based metal composite plate-shaped molded body of the carbon-based metal composite plate-shaped molded product is 0.1mm to 50mm. The method according to claim 1 or 2, The carbon-based metal composite sheet-like molded body has a thermal conductivity of 150 W / (m · K) or more at room temperature in the thickness direction, and a thermal expansion coefficient of 4 × 10 ⁻⁶ / ° C. to 12 × 10 ⁻⁶ / ° C. Carbon-based metal composite plate shaped body having an elastic modulus of 50 GPa or less in the direction of. The method according to any one of claims 1 to 3, A carbon-based metal composite plate-shaped molded body having a density at room temperature of 2.0 g / ml to 2.5 g / ml of the carbon-based metal composite plate-shaped molded body in which the carbon molded body is impregnated with aluminum and an aluminum alloy. The method according to any one of claims 1 to 3, A carbon-based metal composite plate-shaped molded body having a density at a normal temperature of 2.3 g / ml to 5.0 g / ml of the carbon-based metal composite plate-shaped molded body in which the carbon molded body is impregnated with copper, silver, copper alloy and silver alloy. The method of claim 1, The carbon molded body is 10% or more by volume fraction of graphite particles having a long diameter of 0.1 mm to 3 mm or 10% or more by pitch-based carbon fibers having a fiber length of 0.1 mm to 5 mm and carbon fibers produced by vapor phase growth. And a carbon-based metal composite plate-shaped molded body containing 10% or more by volume fraction of graphite particles having a long diameter of 0.1 mm to 3 mm and a pitch-based carbon fiber having a fiber length of 0.1 mm to 5 mm. The method according to any one of claims 1 to 6, A carbon-based metal composite plate-shaped molded body wherein the carbon-based metal composite plate-shaped molded body is a substrate for an electronic device. The surface of the carbon-based metal composite plate-shaped molded article of claim 1 is coated with a metal of plating, molten metal, and metal foil, A ceramic circuit, an electronic device, and a component are connected to a carbon-based metal composite plate-shaped molded article whose cross section is covered with a metal rim through an adhesive layer. An electronic device component, characterized in that. In the method for producing a carbonaceous metal composite plate-shaped molded body in which the carbon molded body is brought into contact with molten aluminum, molten copper, molten silver, and an alloy of these molten metals under pressure, so that the carbon molded body is impregnated with molten metal. (1) heating the carbon molded body at a temperature equal to or higher than the melting point of the molten metal under an inert atmosphere, (2) pressurizing and impregnating the heated carbon molded body by molten forging at a pressure of 200 Kg / cm ² or more per presser unit area using a press device, (3) cooling and solidifying the molten metal after completion of the pressure impregnation in the step (2), (4) a step of taking out the carbon molded body from the coagulated body obtained in the step (3), and (5) Process of shape | molding the metal-impregnated carbon molded object obtained by said process (4) to plate shape. Method for producing a carbonaceous metal composite plate-shaped molded body comprising a.