JPH0624880A - Metal-ceramic material and production thereof - Google Patents

Abstract

PURPOSE:To provide a metal-ceramic composite material excellent in repeated thermal shock resistance and high in reliability and the production method thereof. CONSTITUTION:The metal-ceramic composite material is provided with an alumina or aluminum nitride substrate 1 and at least two layers of tungsten metal layer 3, 5 different from each other in sintering density. Copper or copper alloy 2, 4 is contained in the space between the tungsten particles of the tungsten metal layer. As a result, the thermal stress generated at the boundary different in physical property is mitigated even in an environment of heat shock or heat cycle which gives ambient temp. change or repeated thermal shock and the composite material excellent in durability and reliability is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a metal-ceramic composite and a method for producing the same.

[0002]

2. Description of the Related Art Ceramics have excellent properties such as heat resistance, wear resistance and insulation properties and are used for various purposes. Depending on these uses, a metal-ceramics composite obtained by compositing a ceramic member and a metal member may be required. For example, a metal-ceramics composite is considered as a material applied to applications that must have both heat resistance and heat dissipation, such as outer wall materials of rockets and aircraft, engine members, and the like.

As such a metal-ceramic composite, a composite prepared by dispersing ceramic particles or ceramic fibers in a metal, a composite in which a metal and a ceramic are bonded, and the like are known.

Alumina, aluminum oxynitride, aluminum nitride, boron nitride, and composite ceramics thereof are excellent in thermal conductivity, electrical insulation, and mechanical properties, so that they are used in IC packages, power diodes, etc. As a semiconductor mounting substrate on which the heat-generating component is mounted, a composite body in which a metal circuit board such as copper is bonded to these ceramics is used.

A composite comprising a copper plate and these ceramics is joined by a brazing material containing an active metal, as disclosed in JP-A-60-177634, and JP-A-56-163093. It is a bonded composite produced by a method such as disclosed in the publication, in which a copper plate and a ceramics substrate obtained by surface oxidation treatment are heated and bonded at a temperature not higher than the melting point of copper and not lower than the eutectic temperature of Cu—O to bond them together.

Further, a high thermal conductive insulating substrate in which copper or a copper alloy is directly bonded by heating to an aluminum nitride substrate whose surface is treated with a refractory metal containing voids and a method for producing the same have been disclosed (Japanese Patent Laid-Open No. 3-30083). 137069).

[0007]

However, in the conventional metal-ceramics composite, since the difference in the coefficient of thermal expansion between the ceramics and the metal plate is large, the heat cycle in which the ambient temperature change or the repeated thermal shock is applied is caused. On the other hand, due to the generated thermal stress, peeling is likely to occur between the metal plate and the ceramic, and cracks occur inside the ceramic member, resulting in a decrease in adhesive strength, airtightness, and electrical insulation. Therefore, there is a problem that it is unsuitable for use as a highly reliable component.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a highly reliable metal-ceramic composite having excellent repeated thermal shock resistance and a method for producing the same.

[0009]

[MEANS FOR SOLVING THE PROBLEMS] The metal-ceramic composite according to the present invention comprises an alumina or aluminum nitride ceramic substrate, and at least two layers of tungsten having different sintering densities which are formed on the surface of the ceramic substrate so as to be superposed on each other. A metal layer, and the tungsten particle gap of the tungsten metal layer contains copper or a copper alloy.

Another metal-ceramic composite according to the present invention comprises an alumina or aluminum nitride ceramic substrate and at least two tungsten metal layers having different sinter densities formed on the surface of the ceramic substrate. It is characterized in that the tungsten particle gap of the tungsten metal layer contains copper or a copper alloy, and further comprises a metal plate laminated and bonded on the tungsten metal layer. .

In the method for producing a metal-ceramic composite according to the present invention, a sheet of alumina or aluminum nitride is prepared, and a plurality of tungsten pastes having different grain sizes or sinterability are printed on the sheet to a predetermined thickness. After laminating and sintering, multiple tungsten metal layers with different sintering densities are formed on the alumina or aluminum nitride ceramics substrate, and copper or copper alloy is intruded by heating into the tungsten particle gaps of the tungsten metal layers. It is characterized by

Another method for producing a metal-ceramic composite according to the present invention is to prepare a green sheet of alumina or aluminum nitride, and to form a plurality of tungsten sheets having different grain sizes or different sinterability on the sheet. After laminating and sintering, multiple tungsten metal layers with different sintering densities are formed on the alumina or aluminum nitride ceramics substrate, and copper or copper alloy is intruded by heating into the tungsten particle gaps of the tungsten metal layers. It is characterized by

According to the present invention, in the above-described manufacturing method, nickel plating is performed before copper or a copper alloy is formed by infiltration into the gaps between the tungsten particles of the tungsten metal layer by heating, whereby the tungsten metal layer and A nickel layer may be formed on the surface of the tungsten particles in the layer, or a metal plate may be superposed on the tungsten metal layer and heated to be bonded.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 of the accompanying drawings is a schematic enlarged view of a cross-sectional structure of a metal-ceramic composite body as an embodiment of the present invention. As shown in FIG. 1, the metal-ceramic composite of this example has tungsten-copper alloy layers 3 and 5 and copper and copper alloy layers 2 and 4 on both upper and lower surfaces of a ceramic substrate layer 1. Has become. Then, in this embodiment, the tungsten-copper alloy layer 3 has a thickness of 4
It is composed of three layers 3A, 3B, 3C and 3D, and the tungsten-copper alloy layer 5 is also composed of four layers 5A, 5B, 5C and 5D.

The tungsten-copper alloy layers 3 and 5 have tungsten and copper component contents of layers 3A, 3B, 3C,
It is changed stepwise or continuously between 3D or 5A, 5B, 5C, 5D, and its composition gradient can be arbitrarily selected. That is,
The thermal expansion coefficient, the thermal conductivity, the Young's modulus, the density, the electrical conductivity and the like of tungsten and copper can be arbitrarily changed. Further, by interposing nickel at the interface between tungsten and copper in the tungsten-copper alloy layers 3 and 5, the bonding between the two can be made stronger.
With such a structure, especially against heat shock and heat cycle, thermal stress generated at an interface having different physical properties can be relaxed, and durability and reliability can be made excellent.

As will be apparent from the specific examples described below, the present invention also provides a method for producing such a metal-ceramic composite, but these metal-ceramics of the present invention are also provided. The composite and its manufacturing method are
It was completed as a result of earnest studies by the present inventors. That is, the ceramics used in the present invention,
It is made of alumina or aluminum nitride and has high thermal conductivity and high heat dissipation among various ceramics.
The ceramic substrates used for these may contain sintering aids in addition to unavoidable impurities.

For example, for alumina, MgO, C
aO, SiO₂, Y₂O₃, BaO, Cr₂O₃, Etc.
For aluminum nitride, CaO, Ba
O, SrO, CaCO₃, BaCO₃, SrCO₃, A
Calcium luminate, Y₂O ₃, La₂O₃, CeO₂
Etc.

These ceramic substrates are molded by a general ceramic powder molding method such as a press molding method, a hydrostatic molding method (CIP), a sheet molding method, an extrusion molding method, a casting molding method and an injection molding method. . The molded body is usually sintered at the optimum sintering temperature.

As described above, the tungsten-copper alloy layer may be formed on both upper and lower surfaces of the ceramic molded substrate or the substrate of the sintered body as described above, or may be formed on only one surface. . Also, a ceramic powder compact (green compact) that becomes a ceramic substrate by firing, depending on the particle size of the raw material powder, sinterability, and the selection of sintering aids.
A tungsten layer is formed on the upper side or both sides and co-fired and co-sintered. Further, after forming a tungsten metal layer on the sintered ceramics substrate (or on both sides), firing is performed to sinter.

The tungsten metal layer on these ceramic substrates has a controlled porosity and a graded porosity by selecting raw materials having different grain sizes and sinterability and stacking these materials. , A plurality of continuously stacked tungsten metal skeleton layers can be formed, and by impregnating copper into the skeleton, a tungsten-copper metal layer in which the composition of tungsten-copper changes stepwise and continuously is formed. Can be formed.

After forming the tungsten skeleton layer, a nickel layer is formed on the tungsten metal, for example,
By forming by a method such as nickel plating,
It is possible to strengthen the bond between the tungsten metal and the copper metal at the interface. In addition, as the copper and the copper alloy, other metal or non-metal component may be added and contained in a ratio of 30% by weight or less.

Further, the above-mentioned tungsten-copper layer preferably has three or more metal layers in which the composition of tungsten-copper changes stepwise and continuously in order to improve the thermal shock resistance. The outermost layer preferably has a copper or copper alloy layer having good solder wettability.

In order to increase the adhesion strength of alumina and aluminum nitride to the ceramics substrate, non-metal inorganic components such as sintering aids and flux components other than these substrate components (alumina and aluminum nitride) are 30% by weight or less. And may be contained in the tungsten metal.

As a method of forming a plurality of tungsten metal layers having different sintering densities, tungsten pastes whose grain size and sinterability are controlled are sequentially printed and laminated, or tungsten green sheets are sequentially laminated, for example, by thermocompression bonding. And the like.

The metal-ceramic composite of the present invention as described above becomes useful as a circuit board for mounting semiconductors by forming a circuit pattern on a metal layer or a metal surface.

FIG. 2 is a schematic enlarged view showing a sectional structure of a metal-ceramic composite body as another embodiment of the present invention. As shown in FIG. 2, the metal-ceramic composite of this example has metal plates 6 and 7 on top of the uppermost layers 3D and 5D of the tungsten metal layers 3 and 5 of the composite as shown in FIG. It is made by overlapping and joining. As this metal plate, copper or an alloy mainly composed of copper is preferable, and the metal plates are bonded at the same time when the copper layers 2 and 4 are formed on the tangten metal layers 3D and 5D, or Ag-Cu-Ti. Bonding is performed by using a system active metal brazing material.

Next, some specific examples of the present invention will be described.

(Specific Example 1)

Average particle size 1.0 μm, 1.8 μm, 2.4 μm,
Alumina powder of the same composition as the following alumina green sheet (purity 94%, balance Ca)
10% by weight of O, MgO, and SiO ₂ ) and a vehicle containing terpineol and ethyl cellulose were added and kneaded with a three-roll mill to prepare tungsten pastes A, B, C, and D, respectively. On the other hand, 6% by weight of flux components (CaO, MgO, Si
O ₂ ) -containing raw material powder was added with methacrylic acid ester resin and molded by the doctor blade method to a thickness of 0.8.
mm alumina green sheet was cut into 45 × 45 mm.

About 40 parts of the above-mentioned tungsten pastes A, B, C and D are applied to the upper and lower surfaces of this green sheet.
After printing with a thickness of μm, the process of drying at 80 ° C. was sequentially repeated to obtain an alumina green sheet in which tungsten pastes A, B, C and D were printed and laminated. This printed laminated green sheet was baked at 1600 ° C. in a N ₂ —H ₂ mixed gas. The obtained structure has four tungsten layers on both sides of an alumina substrate, and the layers from the surface layer of the tungsten layer to the third layer form a porous layer in which the upper layer has a higher porosity than the lower layer. In addition, it had a graded structure in which the porosity changed stepwise.

After the vehicle was added to the copper powder (average particle size: 3 μm) on the tungsten layer of the obtained structure, the copper paste prepared by kneading with a three-roll mill was printed at a thickness of 30 μm, and then the temperature was maintained at 1150 ° C. Heated in active gas. A tungsten-copper alloy impregnated with copper is formed in the pores of the tungsten layer, and the content of tungsten in the copper decreases from the upper layer to the lower layer.
It had a graded structure in which the copper composition changed stepwise.

(Specific Example 2)

Average particle size 1.0 μm, 1.8 μm, 2.4 μm,
AlN powder (purity 96%, balance 4% Y ₂ O ₃ ) having the same composition as the following aluminum nitride green sheet was added to 4 kinds of tungsten powder (purity 99.9% or more) each having a different particle size of 3.0 μm. A vehicle containing terpineol and ethyl cellulose with an internal weight percentage of 3 was added,
Kneading with this roll mill, tungsten paste E, F,
G and H were prepared respectively. On the other hand, 4% by weight of Y ₂ O ₃ (average particle size 1.2 μm) was added to AlN powder (average particle size 1.9 μm).
m) was added, a methacrylic acid ester resin was added, and an aluminum nitride green sheet having a thickness of 0.8 mm formed by the doctor blade method was cut into 45 × 45 mm.

About 40 parts of the above-mentioned tungsten pastes E, F, G and H are applied to the upper and lower surfaces of this green sheet.
After printing with a thickness of μm, the process of drying at 80 ° C. was sequentially repeated to obtain an aluminum nitride green sheet in which tungsten pastes E, F, G, and H were printed and laminated. The print laminated green sheets with N ₂ -H ₂ mixture gas 17
It was baked at 50 ° C. The obtained structure has four tungsten layers on both sides of an aluminum nitride substrate, and the layers from the surface layer to the third layer of the tungsten layer are porous layers in which the upper layer has a higher porosity than the lower layer. Formed,
Moreover, it had a graded structure in which the porosity changed stepwise.

After the vehicle was added to the copper powder (average particle size: 3 μm) on the tungsten layer of the obtained structure, the copper paste prepared by kneading with a three-roll mill was printed at a thickness of 30 μm, and then the temperature was maintained at 1150 ° C. Heated in active gas. A tungsten-copper alloy impregnated with copper is formed in the pores of the tungsten layer, and the content of tungsten in the copper decreases from the upper layer to the lower layer.
It had a graded structure in which the copper composition changed stepwise.

(Specific Example 3)

72% by weight of Ag powder (average particle size 1.5 μm), 2% by weight of Ti powder (average particle size 20 μm) and 26% by weight of Cu powder (average particle size 1.5 μm) were pulverized and mixed by an attritor. A vehicle containing ethyl cellulose and terpineol was added, and the mixture was kneaded with a three-roll mill to obtain Ag-Cu.
A Ti-active metal brazing material was prepared. The Ag-C is formed on both upper and lower surfaces of the structures obtained in the specific examples 1 and 2 described above.
A u-Ti active metal brazing material was applied by printing, and a copper plate having a thickness of 0.2 mm was overlaid and bonded in a vacuum at 900 ° C. to obtain a metal-ceramic composite.

(Specific Example 4)

Methacrylic acid ester resin was added to three kinds of tungsten powders (purity 99.9% or more) having different average particle diameters of 1.5 μm, 2.1 μm and 3.0 μm, respectively.
Tungsten green sheets a, b, c having a thickness of 200 μm formed by the doctor blade method were prepared. 45 of the alumina sheet (thickness 0.8 mm) obtained in Example 1
Approximately 30μ of the above-mentioned tungsten paste A on × 45mm
After printing with a thickness of m, it was dried and the above-mentioned tungsten green sheets a, b and c were laminated on the upper and lower surfaces of the alumina green sheet and thermocompression bonded. This green sheet laminate was fired at 1600 ° C. in a N ₂ —H ₂ mixed gas. The obtained structure has four tungsten layers on both sides of an alumina substrate, and the layers from the surface layer of the tungsten layer to the third layer form a porous layer in which the upper layer has a higher porosity than the lower layer. In addition, it had a graded structure in which the porosity changed stepwise.

After the vehicle was added to the copper powder (average particle size 3 μm) on the tungsten layer of the obtained structure, the copper paste kneaded and prepared by a three-roll mill was printed to a thickness of 30 μm, and then the temperature was maintained at 1150 ° C. Heated in active gas. A tungsten-copper alloy impregnated with copper is formed in the pores of the tungsten layer, and the content of tungsten in the copper decreases from the upper layer to the lower layer.
It had a graded structure in which the copper composition changed stepwise.

(Specific Example 5)

Average particle size 1.0 μm, 1.8 μm, 2.4 μm,
Alumina powder of the same composition as the following alumina green sheet (purity 94%, balance Ca)
10% by weight of O, MgO, and SiO ₂ ) and a vehicle containing terpineol and ethyl cellulose were added and kneaded with a three-roll mill to prepare tungsten pastes A, B, C, and D, respectively. On the other hand, 6% by weight of flux components (CaO, MgO, Si
O ₂ ) -containing raw material powder was added with methacrylic acid ester resin and molded by the doctor blade method to a thickness of 0.8.
mm alumina green sheet was cut into 45 × 45 mm.

About 40 parts of the above-mentioned tungsten pastes A, B, C and D are applied to the upper and lower surfaces of this green sheet.
After printing with a thickness of μm, the process of drying at 80 ° C. was sequentially repeated to obtain an alumina green sheet in which tungsten pastes A, B, C and D were printed and laminated. This printed laminated green sheet was baked at 1600 ° C. in a N ₂ —H ₂ mixed gas. The obtained structure has four tungsten layers on both sides of an alumina substrate, and the layers from the surface layer of the tungsten layer to the third layer form a porous layer in which the upper layer has a higher porosity than the lower layer. In addition, it had a graded structure in which the porosity changed stepwise.

The obtained tungsten layer was electrolessly plated with nickel to form a nickel metal layer on the tungsten metal. After adding the vehicle to the copper powder (average particle size 3 μm) on the tungsten layer of the structure thus obtained, 30 μ of the copper paste prepared by kneading with a three-roll mill
After printing with a thickness of m, it was heated to 1150 ° C. in an inert gas. A tungsten-copper alloy impregnated with copper is formed in the pores of the tungsten layer, and the copper content of the tungsten-copper decreases from the upper layer to the lower layer. Had a structure. Further, a nickel layer is present at the interface between tungsten and copper, and the interface between tungsten and copper has a structure in which both are firmly held.

(Comparison between Examples of the Present Invention and Comparative Examples)

72% by weight of Ag powder (average particle size 1.5 μm), 2% by weight of Ti powder (average particle size 20 μm) and 26% by weight of Cu powder (average particle size 1.5 μm) were pulverized and mixed by an attritor. , A vehicle containing ethyl lulose and terpineol was added and kneaded with a three-roll mill to obtain Ag-Cu.
A Ti-active metal braze paste was prepared. Using the obtained active metal brazing material paste, size 36 x 36 mm, plate thickness
A copper-bonded alumina substrate obtained by printing on both sides of a 0.635 mm alumina substrate and stacking 0.2 mm-thick copper plates and bonding them at 900 ° C. in vacuum was prepared as a comparative example.

On the other hand, a copper-bonded copper plate obtained by the method of Example 3 of the present invention so as to have the same size as that of the comparative example.
A tungsten alloy-alumina composite (metal-ceramics composite) was prepared and repeatedly placed in a thermal shock tester together with a copper-bonded alumina substrate of a comparative example, and after being kept at -55 ° C for 30 minutes, heated to 150 ° C, 30 A series of steps for holding for one minute was set as one cycle and subjected to a thermal shock test in which this cycle was repeated. The holding of the test temperature was adjusted by cooling or heating the atmosphere and sending low-temperature or high-temperature air into the testing machine in which the test body was placed. As a result,
The copper-bonded alumina substrate of Comparative Example had cracks in the substrate after 50 cycles, but the metal-ceramic composite of the present invention showed no cracks after 500 cycles.

[0049]

The metal-ceramic composite of the present invention is
Since the structure is as described above, it is possible to relax the thermal stress generated at the interface having different physical properties even under the heat shock or heat cycle environment where the ambient temperature change or the repeated thermal shock is applied, and the durability and the reliability are improved. It is excellent.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view showing a cross-sectional structure of a metal-ceramic composite as an example of the present invention.

FIG. 2 is a schematic enlarged view showing a cross-sectional structure of a metal-ceramic composite body as another embodiment of the present invention.

[Explanation of symbols]

 1 Ceramics Substrate Layer 2 Copper and Copper Alloy Layer 3 Tungsten-Copper Alloy Layer 4 Copper and Copper Alloy Layer 5 Tungsten-Copper Alloy Layer 6 Metal Plate 7 Metal Plate

Claims (10)

[Claims] 1. A tungsten or aluminum nitride ceramic substrate, and at least two layers of tungsten metal having different sintering densities, which are formed to overlap each other on the surface of the ceramic substrate. A metal-ceramics composite, characterized in that copper or a copper alloy is contained in the particle gap. 2. A tungsten or aluminum nitride ceramic substrate, and at least two layers of tungsten metal having different sintering densities and formed on the surface of the ceramic substrate so as to overlap each other. A metal-ceramics composite, characterized in that copper or copper alloy is contained in the particle gaps, and further, a metal plate laminated and bonded on the tungsten metal layer is provided. 3. The tungsten metal layer according to claim 1 or 2, wherein the content of copper or copper alloy contained therein and the content of tungsten are changed stepwise or continuously between the layers. Metal-ceramic composite. 4. The copper or copper alloy layer is provided on the surface of the uppermost layer of the tungsten metal layers.
Alternatively, the metal-ceramic composite according to 2 or 3. 5. The nickel is contained in an interface between tungsten and copper of the tungsten metal layer.
Alternatively, the metal-ceramic composite according to 2 or 3. 6. The non-metal inorganic component such as alumina, aluminum nitride and a sintering aid or a flux component thereof is contained in the tungsten metal layer in a proportion of 30% by weight or less. The metal-ceramic composite according to any one of the above. 7. An alumina or aluminum nitride sheet is prepared, and a plurality of tungsten pastes having different particle sizes or sinterability are printed on the sheet to a predetermined thickness, laminated, and then sintered to obtain alumina. Alternatively, a plurality of tungsten metal layers having different sintering densities are formed on an aluminum nitride ceramic substrate, and copper or a copper alloy is infiltrated by heating into the tungsten particle gaps of the tungsten metal layers to form a metal-ceramic composite. Manufacturing method. 8. Alumina or nitride is prepared by preparing a green sheet of alumina or aluminum nitride, laminating a plurality of tungsten sheets having a predetermined particle size or sinterability and having a predetermined thickness, and then sintering. Manufacture of a metal-ceramic composite characterized in that a plurality of tungsten metal layers having different sintering densities are formed on an aluminum ceramic substrate, and copper or a copper alloy is infiltrated into the gaps between the tungsten particles of the tungsten metal layer by heating. Method. 9. A nickel layer is formed on the surface of the tungsten metal layer and on the surface of the tungsten particle by performing nickel plating before copper or a copper alloy is infiltrated into the gap between the tungsten particles of the tungsten metal layer by heating. The method for producing a metal-ceramic composite according to claim 7, wherein the metal-ceramic composite is formed. 10. The method for producing a metal-ceramic composite according to claim 7, 8 or 9, wherein a metal plate is overlaid on the tungsten metal layer and heated to be bonded.