JP2001220269A - Composite of ceramic material and metal coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite of a ceramic material and a metal coating, having a new structure capable of preventing an alloy from wetting and effusing from a patterned section, while the composite is composed of an aluminum nitride ceramic base material and a Si or Si alloy coating and has the structure where the Si or Si alloy coating is selectively patterned and fused on the aluminum nitride ceramic base material. SOLUTION: This composite of the ceramic material and the metal coating has the structure where the Si or Si alloy coating is subjected to selective patterning so as to form a pattered surface and fused on the aluminum nitride ceramic base material containing a rare earth element compound as a sintering additive, wherein the content of the sintering additive component in an area of the above patterned surface on which the metal coating is not fused and the ceramic base material is exposed is not more than 0.5% when converted into an amount of the rare earth metal oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite of a ceramic and a metal coating, and more particularly, to a composite having a structure in which a coating of Si or a Si alloy is selectively patterned and fused to an aluminum nitride ceramic substrate. It relates to a composite of a ceramic and a metal coating.

[0002]

2. Description of the Related Art The invention of an electric resistor having a structure in which a film (resistance circuit) of Si or a Si alloy is fused to an aluminum nitride base material has been disclosed in connection with the invention of the present inventor (Japanese Patent Laid-Open Publication No. HEI 9-163873). 10-144449). A problem of the present invention is that the alloy is exuded from the patterned circuit (spread of wetness), which protrudes and spreads around the patterned circuit, and a short circuit between the circuits is likely to occur. In particular, in the case of a fine circuit in which the interval between the circuits is narrow, an electrical short circuit is likely to occur. The cause of the alloy bleeding is unknown, does not occur, or is poor in reproducibility,
The cause is still unknown and difficult to solve.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide a new structure of aluminum nitride ceramic and Si or a Si alloy film having a new structure capable of preventing alloy bleeding. The purpose is to provide a complex. A second object is to provide the above composite by a new patterning technique. A third object is to provide a new structure of aluminum nitride ceramic which can prevent exudation of Si or Si alloy.

[0004]

The present inventors have made intensive studies on the above problems, and have obtained the following findings. That is,
Although Si or Si alloy is well wetted and fused to the aluminum nitride ceramic substrate, it has been discovered that the sintering aid in the aluminum nitride substrate is an element that diffuses this wetting. Even if the average component composition of the entire ceramic is the same, the wettability varies due to the variation of the auxiliary component on the outermost surface where the coating is fused, and the as-sintered surface and the surface layer are removed. When the new surface is exposed, the wettability is clearly different, and the new surface has very good wettability, and exudation may occur, which is affected by the amount of auxiliary components remaining on the surface layer. It turns out. In an aluminum nitride ceramic base material using a rare earth element compound as a sintering aid, the amount of the sintering aid on the surface of the aluminum nitride is converted to a rare earth oxide by 0.5% or less, most preferably 0.3% or less. In the following, it was found that spreading of the wetting could be prevented, the wetting did not diffuse outside the patterned portion, no bleeding occurred, and a clear patterned film could be obtained. In an aluminum nitride ceramic substrate using a compound of an alkaline earth metal as a sintering aid, the amount of the sintering aid on the surface of the aluminum nitride is 3% or less, most preferably 1% or less, in terms of alkaline earth metal oxide. %, It was found that wetting did not diffuse outside the patterned portion, no bleeding occurred, and a clear patterned film could be obtained. In addition, the upper limit (the oxide of rare earth element: 0.1.
5%, oxide of alkaline earth metal: 3%).
When fusing an i or Si alloy patterning film, a film with excellent wettability, adhesion, and flatness can be obtained, but wetting spreads from the patterned part and selective patterning can be performed. In this case, it has been found that, in this case, after the coating is once fused without patterning, unnecessary portions may be removed by mechanical removal processing to perform patterning. As a result, it was found that a patterned film having excellent adhesion and flatness was obtained. It has also been found that when the ceramic grain boundaries are etched, bleeding due to the diffusion of wetness of Si or a Si alloy can be prevented. The present invention has been made based on the above findings, and comprises the following claims 1 to 8.

[0005]

A composite of a ceramic and a metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned into a pattern and fused to an aluminum nitride ceramic base material using a rare earth element compound as a sintering aid. Wherein the amount of the sintering aid component in the surface layer portion of the exposed surface of the ceramic substrate on which the coating on the patterning surface is not fused is reduced to 0.5% or less in terms of oxides of rare earth elements. Composite of ceramic and metal coating.

2. The composite of claim 1, wherein said ceramic substrate is a ceramic whose surface is grain boundary etched.

3. An aluminum nitride ceramic substrate containing a sintering aid in an amount exceeding 0.5% in terms of a rare earth element oxide is coated with a Si or Si alloy film selectively on a new pattern. A composite of a ceramic and metal coating having a textured and fused structure, wherein the patterned coating removes unnecessary portions of the coating fused to the nascent surface of the substrate by mechanical removal processing. A composite of a ceramic and a metal coating, characterized by being formed by the above method.

4. The composite of claim 1, wherein said rare earth element is Y.

5. A ceramic and metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned into a pattern and fused to an aluminum nitride ceramic base material using an alkaline earth metal compound as a sintering aid. In the composite, the amount of the sintering aid component in the surface layer portion of the exposed surface of the ceramic substrate which does not fuse the coating on the patterning surface is reduced to 3% or less in terms of alkaline earth metal oxide. Composite of ceramic and metal coating.

6. The composite of claim 5, wherein said ceramic substrate is a ceramic whose surface is grain boundary etched.

7. 3% in terms of alkaline earth metal oxide
A composite of a ceramic and metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned and fused to a new surface of an aluminum nitride ceramic substrate containing a sintering aid in an amount exceeding A composite of a ceramic and a metal coating, wherein the patterning coating is formed by mechanically removing unnecessary portions of the coating fused to the nascent surface of the substrate. .

8. The composite of a ceramic and a metal coating according to claim 5, wherein said alkaline earth metal is Ca.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The Si alloy of the present invention is an alloy having the following microstructure. Si alloy of the present invention and S
The simple substance wets and fuses with the aluminum nitride ceramic regardless of the type and amount of the sintering aid. Also, it wets and fuses with an aluminum nitride ceramic that does not contain an auxiliary component or has no auxiliary component remaining. Microstructure in which silicide and Si are mixed, that is, hypoeutectic, eutectic, and hypereutectic structures having a eutectic structure of silicide and Si, having a eutectic structure of silver, aluminum and Si that do not form silicide with Si Hypoeutectic, eutectic, hypereutectic microstructures The above mixed microstructures The structure of silicide alone Si and Ge are elements with very similar properties and form an all-solid solution. Ge may be added as appropriate.

In the Si alloy of the present invention, in the microstructure in which Si and silicide are mixed, the linear expansion coefficient increases as the amount of silicide increases. The linear expansion coefficient is the largest with silicide alone. In the case of Si alone, the coefficient of linear expansion is minimized. Also silver,
In a microstructure in which aluminum and Si are mixed, the linear expansion coefficient increases as the amount of silver and aluminum increases.

Therefore, when it is necessary to match the coefficient of linear expansion with the aluminum nitride ceramic of the substrate when fusing the coating, by adjusting the amount of silicide phase in the microstructure of the fusing coating, The linear expansion coefficient can be adjusted by adjusting the amounts of the silver and aluminum phases.

The alloy of the present invention has a small linear expansion coefficient such as silicon nitride, aluminum nitride, chromium nitride, and silicon carbide in a coating film by utilizing the property of being wetted and fused to powders such as nitrides and carbides and fibers. The linear expansion coefficient of the coating can also be appropriately adjusted by mixing nitride, carbide powder, fibers, whiskers, etc., and simultaneously wetting and fusing them to the coating alloy.

The aluminum nitride sintered body usually uses a rare earth element compound or an alkaline earth metal compound as a sintering aid. The aluminum nitride ceramics containing the rare earth element compound of the present invention as a sintering aid include Y, La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
oxides of rare earth elements such as o, Er, Tm, Yb and Lu;
Fluoride, hydroxide, carbonate, nitrate or other compounds are added to the sintering material of aluminum nitride for sintering, and the added auxiliary compound is a compound of a rare earth element (mainly aluminate) at the grain boundaries of the sintered body. Aluminum oxide ceramic sintered body which remains in the form of an oxide (e.g., oxide). Also included are aluminum nitride ceramics sintered without auxiliaries or aluminum nitride ceramic sinters in which auxiliaries are not dispersed and remain in the sintering process.

[0011] The amount of these rare earth components remaining on the ceramic surface layer in the portion of the patterning surface where the alloy film of the present invention is not fused is 0.5% or less, most preferably 0.3%, in terms of oxide. %. If it exceeds 0.5%, the molten Si or Si alloy is too wet to the ceramic, so that it spreads out from the fused area of the patterned film and exudes, so that selective pattern formation is not achieved. It is not preferable because it becomes impossible. Widening of the film, short-circuit between the films, collapse of the pattern shape of the film, and the like occur. In particular, it becomes impossible to form a fine pattern. When the coating is used in a heater circuit of a ceramic heater, a short circuit occurs in the circuit.

Here, the term "oxide conversion" means that each rare earth element in the sintered body is present as an oxide of the element and is expressed in terms of its amount (% by weight). For example, Y, La, Ce, Pr, Nd, Sm, G
Elements such as d and Dy are Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ ,
PrO ₂ , Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy
Assuming that it exists as an oxide of a chemical formula such as ₂ O ₃ , it is expressed in terms of its amount (% by weight).

A ceramic sintered without an auxiliary agent or an aluminum nitride ceramic in which the auxiliary component is diffused during the sintering process and the auxiliary component does not remain, naturally, there is no auxiliary in the surface layer portion, so that there is no diffusion of wetting. A fine pattern without short circuit can be formed. Since the portion of the patterned surface where the coating is not fused is naturally included in the category of 0.5% or less of the present invention,
These ceramics are also included in the category of the ceramic of the present invention.

In the present invention, it is not necessary for the entire ceramic to determine the residual amount of the auxiliary component to be 0.5% or less. At least the surface layer portion of the portion where the coating on the patterning surface is not fused may be used. That is, the portion where the coating is fused is 0.5
% May be exceeded.

In the case of a ceramic base material in which an auxiliary component exceeding 0.5% remains, the alloy of the present invention can be prevented from seepage and diffusion by etching the ceramic grain boundaries in the surface layer.
Here, the etching treatment of the ceramic grain boundary means that the auxiliary component compound at the ceramic grain boundary is micro-etched and removed. As a method of etching treatment for preventing bleeding of the present invention, a method by heat treatment as a dry method, a method by plasma etching, and a wet method by a method by acid immersion, a method by molten salt immersion, and the like are effective. Of course, the present invention is not limited to this, and any method is effective regardless of a dry method or a wet method as long as at least grain boundaries can be etched.

The heat treatment method utilizes the property that the auxiliary component on the surface layer is vaporized when the auxiliary component is heated to about 1400 ° C. or more in a reduced-pressure atmosphere or a nitrogen atmosphere. Therefore, the as-sintered ceramic is etched during sintering and cooling, and the auxiliary components at the grain boundaries are vaporized and evaporated.
It is included in the category of the ceramic of the present invention and can be used as it is. Although the auxiliary is vaporized only in the outermost layer, in practice, this depth is sufficient and the exudation and diffusion of the alloy of the present invention is prevented. On the other hand, in plasma etching, the auxiliary component has a higher etching rate than the aluminum nitride component,
By utilizing this difference in speed, only the auxiliary component can be selectively removed by etching.

The auxiliary layer can also be selectively etched and removed by immersion in a heated phosphoric acid bath. The auxiliary layer can be selectively etched and removed even when immersed in a molten alkali or molten salt bath.

Coating a portion of the aluminum nitride surface layer where the coating is not fused by PVD, CVD, sputtering or the like with an aluminum nitride coating having no auxiliary agent is effective in preventing exudation. This is also included in the ceramic of the present invention.

Even in an aluminum nitride ceramic in which the amount of the auxiliary component exceeds 0.5%, the auxiliary component in the surface layer portion after sintering is diffused, and when the alloy of the present invention is fused to this surface, it becomes wet. There is no protruding, and only the surface to which the alloy paste is applied is fused. As the wetting spreads beyond the surface to which the alloy paste is applied, the wettability is improved and bleeding occurs, and the film cannot be patterned by conventional methods such as printing, drawing, and coating. In such a case, it is also effective to once wet the entire surface of the newly-formed surface and fuse it, and then mechanically remove unnecessary portions of the film by blasting, polishing, honing, lapping, or the like to perform patterning.

The aluminum nitride ceramic containing the alkaline earth metal compound of the present invention as a sintering aid is Ca, B
a, Sr and other alkaline earth metal oxides, fluorides, hydroxides, carbonates, nitrates or other compounds are added to the aluminum nitride sintering raw material and sintered, and the added auxiliary is a sintered body. Means an aluminum earth ceramic sintered body remaining in the form of a compound of an alkaline earth metal (mainly an oxide such as aluminate) at the grain boundary of the above.

The amount of the alkaline earth metal compound remaining on the ceramic surface layer portion where the alloy coating of the present invention is not fused is preferably 3% or less, more preferably 1% or less in terms of oxide. If it exceeds 3%, molten S
i, Si alloy is too wet to the ceramic, so that the wet spreads out from the fused area of the patterned coating and oozes out, and oozing occurs between the coating which does not originally fuse the coating. Not preferred. When the coating is used in a heater circuit of a ceramic heater, a short circuit occurs in the circuit.

In the present invention, the remaining amount of the auxiliary component of the alkaline earth metal compound is specified to be 3% or less, as in the case of the rare earth element, and need not be the whole ceramic. At least a portion of a gap between the coating and the coating that does not fuse the coating may be used.

In the case of a ceramic substrate in which an auxiliary component exceeding 3% remains, the auxiliary component may be etched only in the surface layer, as in the case of the rare earth element.

Here, the oxide conversion means that each alkaline earth element in the sintered body is present as an oxide of a chemical formula such as CaO, BaO, SrO or the like, and is converted to the amount (% by weight). Means to display.

When a rare earth element compound and an alkaline earth element compound are used in combination as auxiliary agents and both remain, in this case, in order to prevent bleeding, the upper limit of the rare earth element compound (0.5%) or less is set. And the upper limit of the alkaline earth element compound (3%) or less, and the upper limit of both.

The aluminum nitride ceramic referred to in the present invention is:
Regardless of the presence or absence of the above-mentioned auxiliaries, the color of the ceramic is changed for improving the electrical, mechanical and thermal properties, for improving the dielectric properties, and for improving the machinability. Other ceramic components (alumina, zirconia, titania,
Chromia, BN, SiC, etc.) are all aluminum nitride ceramics to which a small amount is added.

Since the fused film of the present invention has high resistance, excellent heat resistance and oxidation resistance, it can be suitably used as an application (heater) for applying heat to a patterned film to generate heat and a resistor for electric equipment.

The fusion coating of the present invention is also effective as an intermediate metallization layer when joining aluminum nitride and metal. It is also effective as an electrode coating when applying a voltage to the ceramic. In particular, in the case of an aluminum nitride substrate containing an auxiliary agent in an amount exceeding the above upper limit, a fused film in which the diffusion of wetness is intense is obtained, and conversely, a very thin smooth metallized film can be formed. It is suitable. Further, after forming the alloy film of the present invention on the surface, the fusion film is patterned into a predetermined pattern shape, and nickel, gold or the like is plated thereon as necessary, or directly, a predetermined metal material, for example, a copper plate. By soldering and soldering, a joined body such as a heat sink having small thermal stress can be obtained.

[0029]

The present invention will be described by way of examples. Example 1 Ceramic substrate: Aluminum nitride plate whose surface was polished to expose a new surface (containing 5 wt% of itria as a sintering aid) Dimensions: 50 × 50 × 1 mm Thickness of circuit Printed circuit substrate with Si-7 % Ti-5% Mo alloy composition (wt%) is mixed with a metal powder and a PVP alcohol solution, and the paste is screen-printed in a shape of FIG. 1 in a thickness of 300 μm in a shape of FIG. And heated. Circuit width: 2 mm Distance between circuits: 1 mm Although the circuit was fused to the substrate, bleeding occurred due to the spread of wetness between the circuits, and a short circuit occurred partially between the circuits. On the other hand, the surface-treated ceramic substrate is placed in nitrogen,
The same process was performed on the material which had been subjected to heat treatment at 1650 ° C. for 30 minutes to dissipate the auxiliary agent in the surface layer. The circuit was fused to the substrate, there was no bleeding between the circuits, a sharp circuit was formed, and no short circuit occurred. The electrical resistance was 13 ohm. Energization test An AC voltage was applied to the terminals of the circuit and energized. 70 in 5 minutes
It could be heated to 0 ° C. Dissipation of auxiliary materials on the surface layer begins to seep out,
It was confirmed that there was a significant effect in preventing short circuits.

Example 2 Ceramic substrate: Use of aluminum nitride with a polished surface and substantially no sintering aid Dimensions: 50 × 50 × 1 mm Thickness Circuit printing A 10% Ni alloy composition on the ceramic substrate ( wt%)
1 was screen-printed in a 150 μm-thick shape into the shape shown in FIG. 1 and dried, and then heated at 1350 ° C. in a vacuum. Circuit width: 2 mm Distance between circuits: 1 mm The circuit was fused to the substrate, no bleeding between circuits, a sharp circuit was formed, and no short circuit occurred. The circuit resistance was 25 ohms.

Example 3 Sintering aid components and wetting diffusion were tested. Ceramic substrate: After sintering using an aluminum nitride plate containing a rare earth element oxide (auxiliary component) having the composition shown in Tables 1 and 2 in terms of oxide, the surface layer was polished by 1 mm to expose a new surface. Board dimensions: 20 × 20 × 5 mm thickness Circuit printing A paste made by mixing an alloy powder of the composition shown in Tables 1 and 2 and an alcoholic solution of PVP on the surface of the ceramic base material is 30 times.
Screen printing was performed in a shape of FIG. 1 having a thickness of 0 μm, and after drying, it was heated and melted in vacuum at each temperature shown in Tables 1 and 2. Circuit width: 2 mm Distance between circuits: 1 mm Results From this test, it was confirmed that when the amount of the auxiliary component of the rare earth element was 0.5% or less, exudation of the fusion alloy was eliminated.

Example 4 The exuded ceramic of Example 3 was subjected to the etching treatment shown in Table 3 below to test for wetness and exudation. Result The grain boundary of the ceramic substrate was etched, and it was confirmed that the exudation of the Si alloy could be prevented.

Example 5 Sintering aid components and wetting diffusion were tested. Ceramic substrate: An aluminum nitride plate containing an oxide (auxiliary component) of an alkaline earth metal having the composition shown in Table 4 in terms of oxide was used. After sintering, the surface layer was polished by 1 mm to expose a new surface. . Board dimensions: 20 x 20 x 5 mm thickness Circuit printing On a ceramic substrate surface, an alloy powder having the composition shown in Table 4 and PVP
300μm paste made by mixing alcohol solution
After screen printing and drying in the shape of Figure 1, in vacuum,
It heated and melted to each temperature of Table 4. Circuit width: 2 mm Distance between circuits: 1 m
m From this test, the amount of the alkaline earth metal auxiliary component was 3%
In the following, it was confirmed that exudation of the fusion alloy disappeared.

Example 6 Ceramic substrate: Aluminum nitride plate whose surface was polished to expose a new surface (containing 5% of yttria as a sintering aid) Dimensions: 50 × 50 × 1 mm Thickness Printing of coating Film on ceramic substrate A paste made by mixing a metal powder of a Si-7% Cr alloy composition (wt%) and an alcohol solution of PVP is printed on one side with a thickness of 100 μm and dried,
Heated at 1380 ° C. in vacuum. The printed coating was completely fused to one side of the substrate. The film was thin and smooth, and the spread of wetness was intense, and oozing spread to the back surface of the substrate. Next, a resin mask having a circuit pattern thickness of 0.5 mm, a circuit coating width of 2 mm, and a circuit coating interval of 15 mm in FIG. 1 was prepared, attached to the fusion coating, masked, and blasted with alumina powder. The unmasked coating was removed. When the mask was removed, a fused film having the circuit pattern shown in FIG. 1 having an extremely sharply patterned outline was obtained. The circuit coating had no short circuit and had an electrical resistance of 89 ohms. Energization test An AC voltage was applied to the terminals of the circuit and energized. 5 in 10 minutes
It could be heated to 00 ° C.

Example 7 The exuded ceramics of Example 5 were subjected to the etching treatment shown in Table 4 below to test for wetness and exudation. Result The grain boundary of the ceramic substrate was etched, and it was confirmed that the exudation of the Si alloy could be prevented.

[0036]

As described in detail above, the present invention has a structure capable of preventing seepage from the pattern portion due to the wetting of the alloy, and is excellent in heat resistance, oxidation resistance and adhesion strength on the surface of the aluminum nitride substrate. It can form a precise film without short-circuit, and greatly contributes to the creation of new applications and the improvement of performance of the composite of the aluminum nitride ceramic and the metal film.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a circuit pattern of an embodiment.

[Explanation of symbols]

 1: Resistive circuit 2: Ceramic substrate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/20 328 H05B 3/20 328

Claims (8)

[Claims] A composite of a ceramic and a metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned into a pattern and fused to an aluminum nitride ceramic base material using a rare earth element compound as a sintering aid. Wherein the amount of the sintering aid component in the surface layer portion of the exposed surface of the ceramic substrate on which the coating on the patterning surface is not fused is reduced to 0.5% or less in terms of oxides of rare earth elements. Composite of ceramic and metal coating. 2. The composite of claim 1, wherein said ceramic substrate is a ceramic whose surface is grain boundary etched. 3. An aluminum nitride ceramic substrate containing a sintering aid in an amount exceeding 0.5% in terms of a rare earth element oxide is coated with a Si or Si alloy film selectively on a new pattern. A composite of a ceramic and metal coating having a textured and fused structure, wherein the patterned coating removes unnecessary portions of the coating fused to the nascent surface of the substrate by mechanical removal processing. A composite of a ceramic and a metal coating, characterized by being formed by the above method. 4. The composite of claim 1, wherein said rare earth element is Y. 5. A ceramic and metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned into a pattern and fused to an aluminum nitride ceramic base material using an alkaline earth metal compound as a sintering aid. In the composite, the amount of the sintering aid component in the surface layer portion of the exposed surface of the ceramic substrate which does not fuse the coating on the patterning surface is reduced to 3% or less in terms of alkaline earth metal oxide. Composite of ceramic and metal coating. 6. The composite of claim 5, wherein said ceramic substrate is a ceramic whose surface is grain boundary etched. 7. 3% in terms of alkaline earth metal oxide
A composite of a ceramic and metal coating having a structure in which a coating of Si or a Si alloy is selectively patterned and fused to a new surface of an aluminum nitride ceramic substrate containing a sintering aid in an amount exceeding A composite of a ceramic and a metal coating, wherein the patterning coating is formed by mechanically removing unnecessary portions of the coating fused to the nascent surface of the substrate. . 8. The composite of a ceramic and a metal coating according to claim 5, wherein said alkaline earth metal is Ca.