JP2004160549A - Ceramic-metal complex and high heat-conductive substrate for heat radiation using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic-metal complex which precipitates no reactive layer and requires no reaction-preventive layer, which is excellent in both thermal and electric conductivity, and which can be manufactured at low costs. <P>SOLUTION: The ceramic-metal complex comprises a base of which principal constituent is cordierite and which has a plurality of porosities. The porosities are impregnated with at least any one of copper, a copper alloy, aluminum and an aluminum alloy. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a ceramic-metal composite having good thermal conductivity and electric conductivity, and a substrate for high heat conduction and heat radiation using the ceramic-metal composite, and particularly to a high heat used inside a power semiconductor module or as a high-frequency electrode. The present invention relates to a conductive heat dissipation substrate.

  In recent years, the size of transistors has been reduced with the rapid miniaturization and higher density of semiconductor silicon chips, and the degree of integration of ICs (integrated circuits) has been increasing. 2. Description of the Related Art Fine processing and high density of a transistor are mainly performed by two technical methods. One of them is improvement of the transistor itself. In other words, this is a method of controlling the movement of electric charges propagating through a transistor, such as a metal oxide semiconductor (MOS), a complementary MOS (CMOS), or a bipolar CMOS (BiCMOS). The other is a method of controlling the structure of a current inlet / outlet like a double-gate transistor or a multi-gate transistor. In such a transistor, the loss (leakage) of the current when passing through the gate is converted into thermal energy, so that the amount of heat generated from the silicon chip is rapidly increasing.

  Further, as in the case of the above-described IC, higher output and higher integration of semiconductor elements such as thermoelectric elements, LSIs, VLSIs, diodes, and semiconductor laser elements have progressed, and the amount of heat generated from the semiconductor elements tends to increase rapidly. . For this reason, in a highly integrated semiconductor device such as a hybrid IC, a heat sink made of copper or a high melting point metal material is integrated with a ceramic circuit board in order to efficiently dissipate heat from the semiconductor element to the semiconductor element. Used. However, heat sinks made of copper or high-melting point metal have a large difference in thermal expansion coefficient from semiconductor elements and ceramic circuit boards. There was a problem that it was easy.

  In order to solve this problem, there is a need for a heat-conducting heat-radiating substrate for joining a heat-radiating substrate to a semiconductor element and dissipating heat from the semiconductor element to the outside of the system.

  For example, Patent Literature 1 discloses that a substrate made of a Cu-W alloy or a Cu-Mo alloy having a low Cu content is provided with a through-hole, and a Cu-W alloy or Cu having a high Cu content is provided in the through-hole. A heat-dissipating substrate filled with a -Mo alloy so that heat can be conducted in the axial direction of the through-hole is illustrated. Patent Document 1 discloses a semiconductor module in which a thermoelectric element and a semiconductor laser element are joined to a heat dissipation substrate, and these are arranged in a housing.

  Further, the IC is packaged by various methods to manufacture an IC package. For example, the IC package includes BGA (Ball Grid Array), DIP (Dual Inline Package), and PGA (Pin Grid Array). The IC package includes, for example, a semiconductor chip such as silicon, a circuit conductor for transmitting input / output signals from the semiconductor chip, and leads and pins for transmitting input / output signals from outside the IC package. In addition, the structure is hermetically sealed by a casing made of ceramics, plastic, or the like. The IC package having such a structure has a problem that it is broken or malfunctions due to a rise in temperature due to an increase in the amount of heat generated from the silicon chip. In order to suppress the rise in temperature of the silicon chip, a substrate for high heat conduction and heat radiation is bonded to the silicon chip to release heat from the silicon chip to the outside of the system. The problem of separation due to thermal stress at the interface between the semiconductor element and the substrate for high heat conduction and heat dissipation similarly occurs at the interface between the silicon chip and the substrate for heat conduction and heat dissipation.

  Conventionally, a board for high heat conduction and heat dissipation bonded to the silicon chip via solder, and a board for high heat conduction and heat dissipation provided with an insulating layer consisting of a ceramic substrate bonded to a circuit conductor and mounted on a silicon chip via solder Copper has been widely used because its thermal conductivity is as high as 330 W / m · K or more.

However, copper, the thermal expansion coefficient of silicon is 16.5 × ^{10 -6} /℃,4.2×10 ^-6 / ℃ respectively, consisted of the two there is a large difference, the silicon chip is a high temperature After that, there is a problem that the solder deteriorates in a cooling process and the heat dissipation substrate is easily peeled off from the silicon chip.

  At present, in order to solve this problem, it has been studied to adopt a composite material in which pores of a silicon carbide porous sintered body are impregnated with copper as a constituent material of a substrate for high heat conduction and heat radiation. This is because copper has a high thermal conductivity and a thermal expansion coefficient close to that of silicon.

  Such a composite material is obtained, for example, by immersing a porous silicon carbide sintered body in molten copper, pressurizing the copper, and then cooling and solidifying the molten metal as proposed in Patent Document 2. It is manufactured by

Further, Patent Document 3 discloses, as another composite material, a layer that impregnates pores of a silicon carbide sintered body with copper and prevents a reaction between the silicon carbide sintered body and copper at an interface between the two (hereinafter referred to as a reaction). For example, a composite material having a layer formed of ZrC, TiC, TaC, Mo ₄ C ₃ , Cr ₄ C ₃ or the like has been proposed.

  In addition, recently, when the above-described composite material is used as a constituent material of the substrate for high heat conduction and heat radiation, when the ambient temperature is increased, the ceramic-metal composite restrains the expansion of copper, and the silicon chip is restrained. It is also required to have a stress relaxation function.

  Patent Document 4 discloses a heat-dissipating component in which an aluminum layer is provided on the surface of a flat silicon carbide-aluminum composite material in which aluminum is impregnated in a porous silicon carbide body.

  Further, Patent Literature 5 illustrates a heat dissipation member in which a plurality of rods made of a highly thermally conductive metal are embedded in a hole provided in one of the main surfaces of a substrate made of copper or a copper alloy. The heat dissipating member is manufactured by integrally sintering a hole provided in a substrate made of unsintered copper or a copper alloy while inserting the rod.

  Non-Patent Document 1 reports a wetting reaction between a silicon carbide substrate and copper.

Furthermore, in view of recent demands for miniaturization of IC packages and semiconductor modules, not only a heat dissipation function but also a function of inputting and outputting electric signals to and from a heat dissipation board disposed inside the IC package or semiconductor module. It is being considered to have the same.
JP-A-2002-124611 JP-A-11-29379 JP 2001-122682 A JP 2003-204022 A JP 2003-188324 A Interfacial texture formed by the specific wetting reaction between α-SiC / Cu (Journal of the Japan Institute of Metals (1995) Vol. 59)

  However, the heat-dissipating members exemplified in Patent Literatures 1 and 5 have a large thermal expansion coefficient because they are made of only metal. For this reason, when the temperature of the semiconductor element changes, thermal stress has been repeatedly applied to the interface between the semiconductor element and the heat dissipation member due to the difference in thermal expansion between the semiconductor element and the heat dissipation member. There has been a problem that the interface between the semiconductor element and the heat dissipating member is separated due to the thermal stress.

  When a composite material proposed in Patent Document 2 is manufactured by the above-described method, the silicon carbide porous sintered body reacts with copper, and as a result, the silicon carbide porous sintered body and copper A silicon carbide / copper reaction layer was precipitated at the interface with. This silicon carbide / copper reaction layer has a problem that cracks are easily generated, and when used for a substrate for heat conduction and heat radiation, it is extremely difficult to select impregnation conditions for maintaining the heat radiation function. In addition, when the composite material of the silicon carbide porous sintered body and copper is used as a substrate for high heat conduction and heat radiation inside a highly reliable component such as an IC package, when the temperature of the composite material rises, the composite material is subjected to thermal stress. There is a problem that cracks occur and pieces and particles of the silicon carbide porous sintered body are detached, and the pieces and particles come into contact with circuits in the IC package to cause malfunction of the IC package.

  Further, the composite material proposed in Patent Document 2 has a problem that heat radiation is low because the heat radiation area per unit volume of the composite material is small.

  Further, the composite material of Patent Document 2 and the composite material constituting the heat dissipation component of Patent Document 4 have a structure in which a metal lump is discontinuously dispersed and embedded in pores of porous silicon carbide, so that heat is efficiently removed. There was a problem that it was not possible to radiate heat.

Further, the composite material proposed in Patent Document 3 solves the above-mentioned problems. However, a control step for forming a reaction preventing layer, ZrC, TiC, TaC, Mo ₄ C ₃ , and Cr ₄ required material cost of the C _3, etc., was not easy to manufacture.

Further, when this composite material is used as a constituent material of a substrate for high heat conduction and heat dissipation, the silicon carbide sintered body constituting the composite material has a relatively small coefficient of thermal expansion of 4.0 × 10 ⁻⁶ / ° C. However, considering the rise in the ambient temperature during use, it has been desired that the thermal expansion coefficient be lower.

  Further, since the composite materials proposed in Patent Documents 2 and 3 both use a silicon carbide sintered body, a sintering requires a vacuum atmosphere or an inert gas atmosphere, and the production cost is also inexpensive. It was not something.

  Also, Non-Patent Document 1 reports that a silicon carbide / copper reaction layer precipitates at an interface between a silicon carbide substrate and copper, and that cracks are generated in the reaction layer. Could not be used.

  The present inventor has made an effort in view of the above problems, and as a result, has found that a ceramic-metal composite capable of solving the above problems can be provided, and has reached the present invention. That is, the present invention not only prevents the deposition of a reaction layer between ceramics and metal, but also eliminates the need for a reaction prevention layer therefor, has good thermal conductivity and good electrical conductivity in the impregnation direction, and has a low ambient temperature. An object of the present invention is to provide a ceramic-metal composite which can restrain copper expansion even when it rises, does not generate cracks, and can be manufactured at low cost. It is another object of the present invention to provide a ceramic-metal composite in which generation of fragments of ceramics and metal is suppressed.

  The ceramic-metal composite of the present invention has a plurality of through-holes in a base material containing cordierite as a main component, and the through-holes are impregnated with at least one of copper, copper alloy, aluminum, and aluminum alloy. It is characterized by having made it.

  Further, the base is a honeycomb structure having a through hole defined by a plurality of partition plates.

  Further, the substrate is porous.

  Further, the metal is impregnated into the pores of the substrate.

  In addition, a metal layer mainly composed of the metal is formed on at least one main surface of the base, and the metal layer is bonded to a metal impregnated in the through hole.

  Further, the occupied area of the impregnated metal in a cross section orthogonal to the through-hole of the ceramic-metal composite is 50% or more of the cross-sectional area.

  Further, a substrate for high heat conduction and heat radiation of the present invention uses the ceramic-metal composite according to any of the above.

  In a ceramic-metal composite having cordierite as a main component and having a plurality of through holes in a substrate, the through holes are impregnated with at least one metal of copper, copper alloy, aluminum, and aluminum alloy. Since a reaction layer is not deposited at the interface between cordierite and the metal, a ceramic-metal composite having excellent heat conductivity and electric conductivity can be obtained. In addition, by using cordierite as the main component, it enables sintering in the air atmosphere and does not react with any metal of copper, copper alloy, aluminum, and aluminum alloy. The prevention layer can be made unnecessary. As a result, the manufacturing cost can be reduced.

  Further, by forming the substrate as a honeycomb structure having a through-hole defined by a plurality of partition plates, it is possible to obtain a ceramic-metal composite having excellent heat conductivity and electric conductivity particularly in the direction of the through-hole. it can.

  Further, by making the base porous and impregnating the pores with the metal, it is possible to obtain a ceramic-metal composite capable of suppressing the occurrence of cracks during processing even when the base is thin.

  Further, by forming a metal layer containing the metal as a main component on at least one principal surface of the base, and forming a ceramic-metal composite in which the metal layer is bonded to a metal impregnated in a through hole. As a result, the area of the ceramic-metal composite that contributes to heat conduction increases, thereby obtaining a ceramic-metal composite that has particularly good thermal conductivity and suppresses the generation of ceramic and metal fragments. it can.

  In addition, by setting the occupied area of the impregnated metal in the cross section orthogonal to the through-holes to 50% or more of the area of the cross section, in addition to the above-described effects, the thermal conductivity and the electrical conductivity in the impregnation direction are improved. It can be even larger.

  Further, by using the ceramic-metal composite as a substrate for heat conduction and heat dissipation, the function required for the substrate for heat conduction and heat dissipation, that is, the heat dissipation function, the semiconductor element and other components (eg, a ceramic circuit board) are electrically connected. A high heat conducting and radiating substrate that satisfies all of the electric wiring function to connect and the stress relaxation function to the semiconductor element can be provided. The ceramic-metal composite can satisfy the electric wiring function only when the ceramic-metal composite is a dense body, the through-hole of the base is made substantially perpendicular to each main surface of the semiconductor element and the ceramic circuit board, The element, the ceramic-metal composite, and the ceramic circuit board are sequentially laminated via the metal impregnated in the through-hole and electrically connected, so that the semiconductor element is electrically connected to the ceramic circuit board via the metal. This is because signals can be transmitted.

  Hereinafter, the ceramic-metal composite of the present invention will be described with reference to the drawings.

  FIG. 1A is a perspective view showing one embodiment of the ceramic-metal composite 10 of the present invention, and FIG. 1B is a cross-sectional view taken along line X-X ′ in FIG. FIG. 2A is a perspective view of a base 11 having cordierite as a main component and having a through hole 12 and used for manufacturing the ceramic-metal composite 10 of FIG. 1, and FIG. FIG. 3A is a cross-sectional view taken along line XX ′.

  The ceramic-metal composite 10 of the present invention includes a plurality of through-holes 12 in a base 11 mainly containing cordierite, and the through-holes 12 include any one of copper, copper alloy, aluminum, and aluminum alloy. 13 is impregnated.

Since the main component of the base 11 is cordierite, the base 11 does not react with any metal 13 of copper, copper alloy, aluminum, or aluminum alloy impregnating the through-holes 12. No reaction layer is deposited. Further, the base 11 containing cordierite as a main component has a coefficient of thermal expansion of about 0.5 ppm / ° C. at 40 to 400 ° C. and a thermal conductivity of about 1 W / m · K. Compared with the case of using silicon carbide as a main component, copper and a copper alloy originally have a thermal conductivity of 340 to 389 W / m · K and an electric conductivity of 0.41 × 10 ^{6 to} 0.58 × 10 ⁶ S / cm. (Volume specific resistance: 1.72 × 10 ^{−6 to} 2.46 × 10 ⁻⁶ Ω · cm), aluminum, and aluminum alloys have inherent thermal conductivity of 188 to 237 W / m · K and electrical conductivity of 0. 17 × 10 ^{6 to} 0.35 × 10 ⁶ S / cm (volume resistivity: 2.82 × 10 ^{−6 to} 5.75 × 10 ⁻⁶ Ω · cm) is hardly reduced, so that thermal conductivity and impregnation direction are reduced. Good electrical conductivity at It is possible to prevent the occurrence.

  Further, since firing in an air atmosphere is enabled and a reaction prevention layer between the base 11 and the metal 13 does not need to be provided, the manufacturing cost can be reduced.

  The base 11 is preferably porous, and the pores of the base 11 itself as well as the through holes 12 can be impregnated with at least one metal 13 of copper, copper alloy, aluminum, and aluminum alloy. For this reason, in particular, even when the thickness of the ceramic-metal composite 10 is small, it is possible to effectively prevent the occurrence of cracks during processing. When the ceramic-metal composite is porous, fine irregularities are formed inside the through-hole 12, and the metal 13 penetrates into the irregularities and the base 11 and the metal 13 are firmly fixed (anchor effect). Occurs. For example, the metal 13 impregnated in the base 11 and the base 11 are firmly fixed by such an anchor effect, and even when the thickness of the ceramic-metal composite 10 is as thin as 2 mm or less, cracks or Cracks can be suppressed. When the substrate 11 is made porous, the porosity is set to 20% by volume or less to secure the strength of the substrate 11, or the porosity is set to 25% by volume or more and the average pore diameter is set to 3 μm or more, It is preferable to increase the impregnation amount of No. 13 to generate the large anchor effect and prevent cracks and cracks of the ceramic-metal composite. Further, when the base 11 is porous, even if the thickness of the base 11 in the direction of the through hole 12 is small, the base 11 and the metal 13 are firmly fixed by the anchor effect, and the base 11 and the metal 13 are separated during processing. Therefore, the thickness of the base 11 can be reduced. Specifically, when the base 11 is porous, the lower limit of the thickness of the base 11 in the direction of the through holes 12 is preferably three times the average pore diameter of the through holes 12.

  The porosity of the substrate 11 is preferably 30% by volume or more, and the average pore diameter is preferably 4 μm or more, and more preferably the porosity of the substrate 11 is 35% by volume or more, and the average pore diameter is more preferably 5 μm or more.

  When the base 11 is made dense, the strength of the entire ceramic-metal composite is improved. Therefore, if mechanical strength is particularly required, a dense body may be selected. However, when the substrate 11 is dense, specifically, when the porosity of the substrate 11 is about 10% by volume or less, although the mechanical strength is high, the surface of the through hole 12 is hardly formed with irregularities, so that the anchor effect is reduced. However, the base 11 and the metal 13 cannot be firmly fixed to each other, and the base 11 and the metal 13 may peel during processing. For this reason, when the base 11 is dense, it is preferable to increase the thickness of the base 11 in the direction of the through-hole 12 so that the base 11 and the metal 13 are firmly fixed. In particular, when the substrate 11 is dense, it is preferable that the lower limit of the thickness of the substrate 11 in the direction of the through hole 12 is six times the average hole diameter of the through hole 12.

  Next, another embodiment of the ceramic-metal composite of the present invention will be described with reference to FIG.

  FIG. 3 shows a ceramic-metal composite having a plurality of partition plates 26, a honeycomb structure 24 having a through hole 22 defined by the partition plate 26 as a base 21, and a metal 23 impregnated in the through holes 22. FIG. 3 is a perspective view of a body 20. FIG. 4A is a perspective view of a base 21 having cordierite as a main component and having a through hole 22 used for manufacturing the ceramic-metal composite of FIG. 3, and FIG. 4B is a perspective view of FIG. FIG. 4A is a cross-sectional view taken along line XX ′, and FIG. 4C is a cross-sectional view taken along line YY ′ in FIG. Also in this case, as in the case of the ceramic-metal composite 10 as shown in FIG. 1, the base 21 is preferably porous, and the metal 23 can be impregnated not only in the through holes 22 but also in the pores of the base 21 itself. Therefore, in particular, even when the thickness of the ceramic-metal composite 20 is as thin as 2 mm or less, generation of cracks during processing can be effectively suppressed. It is considered that the reason is that the base 21 and the impregnated metal 23 are firmly fixed by the anchor effect. When the substrate 21 is porous, the porosity and the average pore diameter of the substrate 21 are preferably 25% by volume or more and the average pore diameter is 3 μm or more as in the above-described ranges. The reason is as described above. When the thickness of the partition plate 26 is substantially constant, uneven distribution of mechanical stress applied to the partition plate 26 when the metal 23 expands due to an increase in ambient temperature is suppressed. This is preferable because the generation of cracks in the composite 20 can be further suppressed. Further, by forming the base 21 as the honeycomb structure 24 having the through-holes 22 defined by the plurality of partition plates 26, the ceramic-metal composite excellent in heat conductivity and electric conductivity particularly in the direction of the through-holes 22 is provided. 20.

  Still another embodiment of the ceramic-metal composite 10 will be described with reference to FIG.

  5A is a perspective view, FIG. 5B is a cross-sectional view taken along line XX ′ of FIG. 5A, and the ceramic-metal composite 10 has the same upper surface as the metal 13 on the upper end surface of the base 11. It is preferable that the metal layer 14 mainly composed of the material is formed, and the metal layer 14 and the metal 13 impregnated in the through hole 12 are continuous. The reason is that it is possible to obtain the ceramic-metal composite 10 in which the area of the metal 13 contributing to heat conduction is increased, the heat conductivity is further improved, and the generation of ceramic or metal fragments (particles) is suppressed. Because you can.

  Here, the particles and the cause thereof will be described and estimated. When thermal stress is applied to the ceramic-metal composite, it is considered that particles may be generated mainly due to the following three causes.

  The generation of the first particles is caused by applying a thermal stress to the ceramics constituting the ceramic-metal composite 10. Ceramics constituting the ceramic-metal composite 10 are made of polycrystalline cordierite. Polycrystalline cordierite sinters in the sintering process while leaving a considerable amount of mechanical stress inside. When a thermal stress is applied to the ceramic-metal composite, a composite stress C in which a thermal stress is further applied to the mechanical stress is applied to the ceramic. Due to the composite stress C, a part of the crystal grains and the grain boundary phase of the polycrystalline cordierite are separated and become particles.

  The generation of the second particles results from the application of thermal stress to the metal 13. As described in the method of manufacturing the ceramic-metal composite 10 of the present invention described later, the metal 13 is impregnated into the through-hole 12 in a state of being melted at a high temperature and then cooled. During this cooling process, the metal 13 may become polycrystalline or very rarely become amorphous when cooled rapidly. The polycrystalline or amorphous metal 13 may generate and remain mechanical stress inside during the cooling process. When a thermal stress is applied to the ceramic-metal composite, a composite stress M in which a thermal stress is further applied to the mechanical stress is applied to the metal 13. Due to the composite stress M, a part of the metal 13 is separated and becomes a particle.

  The generation of the third particles is caused by a difference in thermal expansion coefficient between the polycrystalline cordierite and the metal 13. When thermal stress is applied to the ceramic-metal composite, due to the difference in the coefficient of thermal expansion between the ceramic and the metal 13, the portion where the ceramic and the metal 13 are in contact, that is, the through hole 12 of the polycrystalline cordierite and the metal A local stress is generated at the interface with the substrate 13. The ceramic-metal composite 10 of the present invention can suppress the occurrence of cracks and cracks even when the local stress is applied. However, when this local stress is repeatedly applied microscopically, a part of the cordierite crystal or the metal 13 becomes fine particles at the interface and separates to become particles.

  It is considered that the second particles hardly occur among these three generation causes. The reason is that the metal 13 has much higher ductility than polycrystalline cordierite and can undergo large elastic deformation, so that it is considered that a part of the metal 13 hardly comes off. . On the other hand, the generation of the first and third particles is much more than the generation of the second particles in view of the fact that cordierite is a brittle material compared to metal and is brittle against repeated stress. It is inferred that: Therefore, by providing the metal layer 14 on the main surface of the ceramic-metal composite 10, the generation of the first and third particles can be suppressed, and as a result, the amount of particles generated from the ceramic-metal composite 10 can be reduced. It is thought that it is possible.

  Although not shown, the metal layer 14 is formed on the ceramic-metal composite 20 shown in FIG. 3 to prevent cracks during processing even when the thickness of the ceramic-metal composite is as thin as 0.8 mm or less, for example. Can be suppressed.

  Further, in the ceramic-metal composites 10 and 20, it is preferable that the occupied area of the impregnated metals 13 and 23 in the cross section orthogonal to the through holes 12 and 22 is 50% or more of the area of the cross section. The reason is that by increasing the ratio of the metals 13 and 23 compared to the bases 11 and 21, it is possible to maintain high thermal conductivity and high electrical conductivity. Can be suitably used. On the other hand, when the area occupied by the metals 13 and 23 is less than 50%, the thermal conductivity and the electrical conductivity cannot be significantly improved.

  Next, a method for producing the ceramic-metal composites 10 and 20 of the present invention will be described.

  First, a base 11 having cordierite as a main component as shown in FIG. 2 and having a plurality of parallel through holes 12 is prepared.

  Here, when the substrate 11 is made porous, firstly, 20 to 35% by weight of water and cellulose or the like as a binder are added to 100% by weight of a mixed material consisting of kaolin, talc, alumina or heiligite as primary materials. After the raw materials added and mixed by 10% by weight are sufficiently kneaded with a kneading machine, a molded body of the base 11 can be obtained by molding by extrusion molding.

  As described above, when the substrate 11 is made to be porous with a porosity of 25% by volume or more and an average pore diameter of 3 μm or more, the particle size of the primary raw material may be 5 to 20 μm. In addition, cordierite itself has a primary material particle diameter smaller than 1 μm and is densified to a porosity of 20% by volume or less. Above that, the cordierite becomes a porous body, and if the particle diameter of the primary material is increased, the pore diameter increases. .

  Then, the molded body is fired in the air atmosphere at 1300 to 1400 ° C. for 2 to 5 hours to obtain the base 11.

  Here, an example of extrusion molding is described as an example, but after adding 50 to 100% by weight of water and 1 to 10% by weight of a binder such as PVA to 100% by weight of the primary raw material, spray granulation is performed. By performing granulation using the method, it is also possible to produce a molded body using a dry press molding method, a cold isostatic press molding method, or the like.

The chemical composition of the porous substrate 11 thus obtained is, for example, 10 to 18% by weight of Mg in terms of MgO, 42 to 62% by weight of Si in terms of SiO ₂ , and Al in terms of Al ₂ O ₃ . 22-44 is in the range of weight percent, MgO is a theoretical composition of cordierite: 13.7 _wt%, SiO 2: 51.4 _{wt%, Al} 2 O 3: chemical composition close to 34.9 wt% Is more preferred.

  On the other hand, when the base 11 is made dense, for example, first, kaolin, talc, alumina, or heidilite as a primary raw material is stirred and mixed, and then calcined at a temperature of 1450 ° C. or more to obtain a cordierite composition. I do. Then, the calcined and synthesized raw material is pulverized to a fine powder having an average particle size of 2 μm or less, and 50 to 100% by weight of water, 100% by weight of the cordierite raw material, and a sintering aid 1 such as rare earth oxide. After adding and mixing 10 to 10% by weight of PVA (polyvinyl alcohol) or 1 to 10% by weight of PEG (polyethylene glycol) as a binder, granulating the mixture by spray granulation or the like, filling the mixture into a predetermined mold, A molded body of the base 11 can be obtained by molding means such as press molding and cold isostatic pressing.

  Then, similarly to the case of the porous body, the base 11 is obtained by firing in an air atmosphere at 1300 to 1400 ° C. for 2 to 5 hours.

As described above, to make the substrate 11 dense, the primary raw material particle size may be reduced. For example, the chemical composition of the obtained substrate 11 is such that Mg is 11 to 15% by weight in terms of MgO, and Si is in terms of SiO _2. 49 to 54% by weight, Al is in the range of 32 to 38% by weight in terms of Al ₂ O ₃ , and the theoretical composition of cordierite is MgO: 13.7% by weight, SiO ₂ : 51.4% by weight, Al ₂ O ₃ : More preferably, the chemical composition is close to 34.9% by weight.

  Next, the base 11 is heated in advance and fixed in a carbon mold, and at least one of copper or copper alloy melted at about 1200 ° C. or aluminum or aluminum alloy melted at about 800 ° C. Then, the mixture is impregnated with pressure at 10 to 300 MPa, and then cooled, whereby the ceramic-metal composite 10 as shown in FIG. 1 can be obtained.

  The heating atmosphere of the ceramic-metal composite 10 or the pressure impregnation atmosphere of the metal is preferably a nitrogen atmosphere or an inert gas atmosphere, but the heating atmosphere and the atmosphere in the pressure impregnation may be the air atmosphere. .

  In addition, the metal to be impregnated may be at least one selected from tough pitch copper, oxygen-free copper, phosphorous deoxidized copper, free-cutting copper, chromium copper, and zirconium copper as copper or a copper alloy. From the viewpoint, it is preferable to select tough pitch copper, oxygen-free copper, and phosphorus deoxidized copper. On the other hand, when weight reduction is required, aluminum or an aluminum alloy may be used rather than copper or a copper alloy. At least one type may be selected. In particular, it is preferable to select A1050, A1070, A1080, A1085, and A1100 because the thermal conductivity and the electrical conductivity are higher.

  The ceramic-metal composite 10 shown in FIG. 1 can be manufactured by the above-described manufacturing method.

  Further, as shown in FIG. 3, a ceramic-metal composite 20 including a honeycomb structure 24 having a through hole 22 in which a base 21 is partitioned by a plurality of partition plates 26 is used as the base 21 with the honeycomb structure 24 shown in FIG. Can be produced in the same manner as in the above-mentioned production method except for using.

  1 and 3, a metal layer 14 mainly composed of the same metal as the metals 13 and 23 is formed on at least one main surface of the ceramic-metal composites 10 and 20. The ceramic-metal composites 10 and 20 bonded to the metals 13 and 23 impregnated in the metal can be manufactured, for example, as follows.

  First, the metal layer 14 can be formed on the main surface of the ceramic-metal composite 10 by electroless plating of copper or aluminum. Second, a metal layer 14 can be provided on the main surfaces of the ceramic-metal composites 10 and 20 shown in FIGS. Third, a metal salt (a nitrate, an oxalate, or the like) containing the same metal as the metals 13 and 23 is dissolved in water, and the solution in which the metals 13 and 23 are present as ions is added to the solution shown in FIGS. The metal layer 14 can be provided by applying, drying, heat-treating, and reducing the main surfaces of the ceramic-metal composites 10 and 20. Fourth, a heat-resistant container having a flat bottom is prepared, one main surface of the bases 11 and 21 is horizontal to the bottom of the heat-resistant container, and a gap is provided between the bases 11 and 21 and the bottom of the heat-resistant container. The through holes 11 and 21 are impregnated with the metal 13 and 23 melted at 1200 ° C. in a nitrogen atmosphere at 70 MPa in a nitrogen atmosphere while the bases 11 and 21 are placed in a heat-resistant container, and then cooled. -Produce metal composites 10 and 20. Further, when the metals 13 and 23 are impregnated with pressure, the other main surfaces of the bases 11 and 21 are cooled while being filled with the molten metals 13 and 23, so that both main surfaces of the bases 11 and 21 are cooled. The ceramic-metal composite 10 having the layer 14 formed thereon can also be manufactured.

  Although FIGS. 1 and 5 show a case where the cross-sectional shape of the through-hole 12 in the ceramic-metal composite 10 is circular, the cross-sectional shape of the through-hole 12 may be an ellipse, a triangle, a quadrangle, or the like. Any shape may be used without departing from the range.

  Further, the ceramic-metal composites 10 and 20 shown in FIGS. 1, 3 and 5 can be suitably used as a substrate for high heat conduction and heat dissipation, and have a heat dissipation function, a semiconductor element and other components (for example, a ceramic circuit board). ), The substrate for high heat conduction and heat radiation of the present invention which satisfies all of the electric wiring function for electrically connecting the semiconductor device and the stress relaxation function for the semiconductor element. The ceramic-metal composites 10 and 20 can satisfy the electric wiring function only when the through holes 12 and 22 of the bases 11 and 21 are substantially perpendicular to the respective main surfaces of the semiconductor element and the ceramic circuit board. -The metal composites 10 and 20 and the ceramic circuit board are sequentially laminated via the metals 13 and 23 impregnated in the through holes 12 and 22 and are electrically connected to each other, thereby forming a semiconductor via the metals 13 and 23. This is because an electric signal can be transmitted from the element to the ceramic circuit board.

The reason for having the heat radiation function and the electric wiring function is that each of the heat conductivity and the electric conductivity is good. In addition, the use of cordierite, which has a coefficient of thermal expansion as low as about 1.1 × 10 ⁻⁶ / ° C. among ceramics, has a stress relaxation function, so that even if the ambient temperature increases, the impregnated metal can be used. This is because expansion can be restrained.

  It should be noted that the ceramic-metal composite of the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the present invention.

  Next, examples of the present invention will be described.

  As a sample according to the present invention, a ceramic-metal composite 10 containing cordierite as a main component as shown in FIG. 1 and a ceramic-metal composite 20 having a base made of a honeycomb structure as shown in FIG. 3 were prepared. . The substrates 11 and 21 were adjusted so that the porosity was 30 to 50% by volume and the average pore diameter was 4 to 8 μm.

  As a comparative example, a ceramic-metal composite including silicon carbide as a main component and a metal carbide as a reaction preventing layer was prepared so as to have a shape similar to that of FIGS.

  The ceramic-metal composite shown in FIG. 1 was a ceramic-metal composite having 600 through-holes having a diameter of 1.04 mm and the through-holes being arranged radially.

  Further, the ceramic-metal composite shown in FIG. 3 has 600 through holes in a lattice shape, has a square cross-section, and has a side of 1.04 mm in one side of the square. A substrate made of a honeycomb structure having a width of 0.19 mm was used.

  Each of the through holes was pressure-impregnated with copper melted at 1200 ° C. or aluminum melted at 800 ° C. at 70 MPa in a nitrogen atmosphere.

  Other specifications of the ceramic-metal composite were prepared as shown in Table 1, and the thermal expansion coefficient, thermal conductivity, and volume resistivity of each ceramic-metal composite were measured.

  The coefficient of thermal expansion, thermal conductivity, and volume resistivity are based on JIS R 1618-1994, JIS R 1611-1991, and JIS C 2141-1992, respectively, and are determined by the JIS standard from the base of each sample. Was cut out and measured.

  For the presence or absence of a crack in the reaction layer, a cross section of each ceramic-metal composite was observed at a magnification of 1000 using a scanning electron microscope (SEM).

  As for cracks, 10 ceramic-metal composites (10 mm thick) were prepared for each sample, and each was ground using a surface grinder to a thickness of 1 mm. The number of cracks was checked, and the number is shown in Table 1.

As is clear from the results in Table 1, the sample No. impregnated with copper as a comparative example. The thermal expansion coefficient of each of Samples 1 and 2 is 10.3 × 10 ⁻⁶ / ° C., whereas the sample No. 1 impregnated with the copper of the present invention. The coefficient of thermal expansion of 3 to 12 shows a small value of 10.2 × 10 ⁻⁶ / ° C. or less, which is good.

In addition, Sample No. impregnated with aluminum as a comparative example. Samples Nos. 13 and 14 each had a coefficient of thermal expansion of 12.6 × 10 ⁻⁶ / ° C., while Sample No. 13 impregnated with aluminum of the present invention. The coefficient of thermal expansion of 15 to 24 is as small as 12.4 × 10 ⁻⁶ / ° C. or less, which is good.

  When aluminum is impregnated, the thermal expansion coefficient tends to be higher as a whole than when copper is impregnated.However, when weight reduction is required, a ceramic structure or honeycomb structure impregnated with aluminum is required. It is more effective to use.

  In addition, the sample No. of the present invention. The thermal conductivity of Sample Nos. 15 to 24 was 190 to 203 W / m · K. In contrast to the thermal conductivity of Sample Nos. The thermal conductivity of 3 to 12 shows a large value of 250 to 258 W / m · K, which is particularly good.

In addition, the sample No. in which the occupied area ratio of copper was 40%. Samples Nos. 3, 4, 11, and 12 have a volume resistivity of 8.8 × 10 ^{−6 to} 9.0 × 10 ⁻⁶ Ω · cm, and a copper occupation area ratio of 50% or more. No. Nos. 5 to 10 have a low volume resistivity of 2.0 × 10 ^{−6 to} 2.3 × 10 ⁻⁶ Ω · cm, and have reached a value desired as a substrate for high heat conduction and heat radiation. is there. Further, in sample No. having an aluminum occupation area ratio of 40%. Samples Nos. 15, 16, 23, and 24 have a volume resistivity of 9.0 × 10 ^{−6 to} 9.2 × 10 ⁻⁶ Ω · cm, and an aluminum occupied area ratio of 50% or more. . Samples Nos. 17 to 22 have good volume resistivity, which is as low as 2.2 × 10 ^{−6 to} 2.4 × 10 ⁻⁶ Ω · cm.

  Regarding the reaction layer and cracks, sample No. Samples Nos. 1, 2, 13, and 14 show that there was no precipitation or cracking of the reaction layer because the reaction prevention layer was formed. Nos. 3 to 12 and 15 to 24 are satisfactory without deposition and cracking of the reaction layer even without the reaction prevention layer.

The following results were obtained for cracks after grinding each of the 10 samples to a thickness of 1 mm. Sample No. In Nos. 11, 12, 23, and 24, the metal was impregnated into the through holes and the pores, so that no cracks occurred. Sample No. In Nos. 3 to 10, and 15 to 22, only one of ten through holes was broken because metal was impregnated only in the through holes.

  A plurality of each of the samples of Example 1 were further prepared, and a metal layer 14 was formed on one main surface (the upper surface in FIGS. 1 and 3) or both main surfaces (the upper and lower surfaces in FIGS. The fee No. 25 to 44 were produced.

  As a first method, a metal layer 14 was formed by electroless plating copper or aluminum on the main surface of the same sample as in Example 1. As a second method, a metal layer 14 was formed by spraying copper or aluminum on the main surface of the same sample as in Example 1. As a third method, a 1M-copper nitrate aqueous solution or a 1M-aluminum nitrate aqueous solution is coated on the main surface of the same sample as in Example 1, dried, heat-treated in air at 500 ° C. for 1 hour, and then reduced in hydrogen. The metal layer 14 was repeatedly formed on the main surface.

  As a fourth method, a sample made of a ceramic-metal composite was produced in the same manner as in Example 1 except for the following conditions. A carbon container having a flat bottom surface is prepared, one of the main surfaces of the bases 11 and 21 and the bottom surface of the heat-resistant container are made horizontal, and a gap is provided between the bases 11 and 21 and the bottom surface of the carbon container. With the 21 in the carbon container, the through holes 11 and 21 are impregnated with copper melted at 1200 ° C. or aluminum melted at 800 ° C. under pressure of 70 MPa in a nitrogen atmosphere, cooled, and cooled on one main surface. A metal layer 14 was formed. Further, at the time of pressure impregnation, the metal layers 14 were formed on both main surfaces of the substrates 11 and 21 by cooling while filling the other main surfaces of the substrates 11 and 21 with the molten metals 13 and 23. .

  The thermal conductivity and the volume resistivity of the obtained sample were measured in the same manner as in Example 1. When the measurement sample was cut out, the metal layer 14 (upper surface or both surfaces) was included in the measurement sample.

As shown in Table 2, the sample of Example 2 had higher thermal conductivity and lower volume resistivity than the sample of Example 1.

  The amount of particles generated from the samples manufactured in Example 1 and Example 2 was measured as follows.

The sample was suspended in pure water in a beaker using a thin metal wire, and ultrasonic waves were applied to the sample in an ultrasonic cleaner for 1 minute. Thereafter, a sample suspended on a metal wire was taken out of the beaker, and particles in pure water were measured with a particle counter (DHA-1000 manufactured by BRANSON). The amount of particles in Table 3 is a value obtained by converting the number of measured particles into the number per 1 cm ² of the surface area of the ceramic-metal composite. In addition, the amount of particles was divided into the amount of particles of 0.5 to 2 μm and the amount of particles of 0.5 μm or less based on the measurement result.

From Table 3, no particles of 0.5 to 2 μm were detected from the samples of Example 1 and Example 2. However, the amount of particles of 0.5 μm or less was smaller in the sample of Example 2 than in the sample of Example 1.

FIG. 1A is a perspective view showing one embodiment of the ceramic-metal composite of the present invention, and FIG. 1B is a cross-sectional view taken along line X-X ′ in FIG. FIG. 2A is a perspective view showing a substrate of the ceramic-metal composite of FIG. 1, and FIG. 2B is a cross-sectional view taken along line X-X 'of FIG. 2A. It is a perspective view showing other embodiments of a ceramics-metal composite of the present invention. FIG. 4A is a perspective view showing a substrate of the ceramic-metal composite of FIG. 3, FIG. 4B is a cross-sectional view taken along line XX ′ of FIG. 4A, and FIG. It is sectional drawing in the YY 'line of (a). FIG. 5A is a perspective view showing still another embodiment of the ceramic-metal composite of the present invention, and FIG. 5B is a cross-sectional view taken along line X-X ′ in FIG.

Explanation of reference numerals

10, 20: Ceramic-metal composite
11, 21: Substrates 12, 22: Through holes 13, 23: Metal 14: Metal layer 24: Honeycomb structure 26: Partition plate

Claims (7)

A ceramic-metal having a plurality of through-holes in a base material containing cordierite as a main component and impregnating the through-holes with at least one metal of copper, copper alloy, aluminum, and aluminum alloy. Complex. The ceramic-metal composite according to claim 1, wherein the base is a honeycomb structure having a through hole defined by a plurality of partition plates. The ceramic-metal composite according to claim 1, wherein the substrate is porous. The ceramic-metal composite according to claim 3, wherein pores of the substrate are impregnated with the metal. The metal layer containing the metal as a main component is formed on at least one main surface of the base, and the metal layer is connected to the metal impregnated in the through-hole. A ceramic-metal composite according to any one of the above. The ceramic-metal composite according to any one of claims 1 to 8, wherein an occupied area of the impregnated metal in a cross section orthogonal to the through hole is 50% or more of an area of the cross section. A substrate for high heat conduction and heat radiation, comprising the ceramic-metal composite according to claim 1.

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