JPH0227310B2 - SERAMIKUSUNOMETARAIZUHO - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for metallizing ceramics. Conventional technology and its problems Although ceramics generally have excellent heat resistance, abrasion resistance, and insulation properties, they have poor impact resistance, so they are often used as structural materials in conjunction with metals. . When joining ceramics and metal, it is necessary to metalize the surface of the ceramic in advance, and when using ceramic as a conductive material, the surface must also be metalized. As methods for metallizing ceramics, the Telefunken method, active metal method, hydride compound method, oxide solder method, silver carbonate method, etc. are known, but methods other than the Telefunken method are rarely used. This is because not only the process is complicated, but also the adhesive strength, thermal shock resistance, chemical resistance, etc. of the obtained metallized layer are often insufficient.
In the currently commonly used Telefunken method, the ceramic surface is coated with molybdenum-manganese, baked at a high temperature of about 1400 to 1700°C in a non-oxidizing atmosphere, and then metal plated.
Then, by heating again in a non-oxidizing atmosphere, a stabilized metallized layer is formed.
However, this method also requires a complicated multi-step process and has drawbacks such as high heating temperature. As a result of conducting research to eliminate the above-mentioned drawbacks of the prior art, the present inventors discovered that at least one of copper carbonate, copper sulfate, copper sulfide, copper oxide, and copper chloride.
A mixture with at least one of SiO ₂ and kaolin,
Alternatively, when using a compound obtained by adding tin oxide to the above mixture, or a compound obtained by adding at least one of palladium, palladium oxide, and platinum chloride to the above mixture as a coating material for ceramics, it is possible to use a simple method at a relatively low temperature. discovered that a metallized layer with excellent physical properties such as adhesive strength, thermal shock resistance, chemical resistance, and electrical conductivity could be formed on ceramics through a process that
Patent applications have already been filed for inventions based on these findings (JP-A-59-207887, JP-A-60-
No. 21888, JP-A-61-86488, JP-A-61-146778
issue). Means for Solving the Problems As a result of further research into metallization methods for ceramics, the present inventor discovered that copper compounds such as copper carbonate,
When using a mixture consisting of at least one of SiO ₂ and kaolin and at least one of rare earth elements and their compounds as a coating material for ceramics, it is possible to use a metallized layer with excellent physical properties that can be easily operated at low temperatures. was found to be obtained. That is, the present invention provides (i) at least one of copper carbonate, copper sulfate, copper sulfide, copper oxide, and copper chloride; (ii)
at least one of SiO ₂ and kaolin, and (iii)
The present invention relates to a method for metallizing ceramics, which is characterized in that a mixture consisting of at least one rare earth element and its compound is applied to the surface of ceramics, baked at 900 to 1300°C in an oxidizing atmosphere, and then the baked layer is subjected to reduction treatment. Copper carbonate used as a coating material in the present invention,
Copper sulfate, copper sulfide, copper oxide and copper chloride are all usually used in powder form. The particle size of the powder is not particularly limited, but is usually less than 100 μm, preferably
It is 50μm or less. SiO ₂ and kaolin are also preferably used as powders, the particle size of which is similar to that of the above compounds. The rare earth elements used as other components of the coating material in the present invention include scandium (atomic number 21),
Yztrium (atomic number 39) and from atomic number 57
There are 15 elements, totaling 17 elements. These are
It is classified into cerium group rare earth elements consisting of La, Ce, Pr, Nd, Pm and Sm and yttrium group rare earth elements consisting of other elements, but cerium group rare earth elements have higher adhesive strength etc. of metallized layer. It is more preferable because it improves the physical properties to a greater extent. Rare earth elements may be used in the form of compounds such as carbonates, oxalates, phosphates, nitrates, sulfates, oxides, hydroxides, peroxides, halides, and sulfides. Rare earth elements and their compounds are
It is preferable to use it as a powder, and its particle size is also the same as that of the copper compound. Incidentally, the chemical properties of rare earth elements are very similar, and in the present invention, each of them has almost the same effect.
Therefore, mixed minerals such as monazite can be used as the rare earth element source. The proportion of each component used in the coating material of the present invention is approximately 80 to 30% by weight of at least one of copper carbonate, copper sulfate, copper sulfide, copper oxide, and copper chloride, and 5 to 30% by weight of at least one of SiO ₂ and kaolin. (preferably 7 to 20% by weight), at least one of rare earth elements and their compounds, about 10 to 60% by weight (preferably 20% by weight)
~50% by weight) is appropriate. If SiO ₂ and/or kaolin is less than 5% by weight, the surface smoothness and gloss of the metallized layer may become insufficient, while if it exceeds 30% by weight, the conductivity of the metallized layer will decrease. There is a tendency to If the content of at least one of the rare earth elements and their compounds is less than 10% by weight or more than 60% by weight, the adhesive strength of the metallized layer will not be sufficiently improved, so either is not preferred. The method of the present invention is usually carried out as follows. The coating material having the above composition is sprinkled or applied in powder form or in the form of a paste onto the ceramic surface on which the metallized layer is to be formed. In the case of making a paste, an appropriate amount of a binder and its solvent, such as balsam and screen oil, may be added to the powder mixture. The amount applied to ceramics is not particularly limited, and is appropriately determined depending on the desired thickness of the metallized layer. Next, the ceramic coated with the coating material is heated in an oxidizing atmosphere to bake the coating layer. The oxidizing atmosphere is not particularly limited, but there is no need to use a special atmosphere, and air, a mixture of air and nitrogen, or the like may be used. The heating conditions depend on the shape and dimensions of the ceramics,
Although it may vary depending on the composition of the coating material and the amount applied, it is usually heated at about 900 to 1300°C for about 5 to 60 minutes.
In this way, copper compounds other than copper oxide become copper oxide, rare earth elements and/or their compounds become oxides, and a coating mainly composed of copper oxide and rare earth element oxides and containing SiO ₂ and/or kaolin powder is formed. Adheres to ceramics. At this time, a portion of the copper oxide melt permeates into the ceramics, thereby improving the adhesive strength of the resulting metallized layer. In addition, the combined use of rare earth elements and/or their compounds not only significantly improves the adhesive strength of the metallized layer, but also greatly improves chemical resistance. Furthermore,
The use of SiO ₂ and/or kaolin significantly increases the homogeneity, surface smoothness and gloss of the metallization layer. If the heating temperature is less than 900℃,
Since the penetration of the copper oxide melt into the ceramic is insufficient, the adhesive strength is insufficient. On the other hand, if the temperature exceeds 1300°C, the viscosity of the coating layer decreases and there is a risk of it flowing out. Next, the ceramic on which the baked layer has been formed as described above is subjected to a reduction treatment. The reduction method is not particularly limited as long as the copper oxide and rare earth element compound is reduced to copper and rare earth element. Typical reduction treatment methods include heating in a reducing atmosphere such as a hydrogen atmosphere or carbon monoxide atmosphere, immersion in an alcohol such as ethanol, methanol, or propanol, or immersion in a reducing solvent such as petroleum benzine or formaldehyde. Examples include immersion, immersion in a dimethylamine borane aqueous solution, and the like. When heating in a reducing atmosphere, the temperature is preferably lower than the baking temperature to prevent decomposition and alteration of the baked layer, and is usually about 200 to 900°C, and the time is usually about 5.
~60 minutes. In addition, in the case of immersion in a reducing solvent, the ceramic is usually heated to about 200 to 500°C, preferably around 300°C, and then soaked in the reducing solvent.
Just soak it for about 10 to 60 seconds. In addition, in the case of immersion in a dimethylamine borane aqueous solution, the ceramic is usually heated to about 40 to 60°C, and then immersed in the aqueous solution for 10 minutes.
Just soak for ~60 seconds. By the above reduction treatment, a metallized layer made of copper and rare earth elements having extremely excellent conductivity is formed on the ceramic surface. If necessary, various metals can be easily joined to the thus metallized ceramics by conventional methods such as brazing. Ceramics that can be metallized according to the present invention are not particularly limited, and include non-oxide ceramics such as silicon nitride, sialon, silicon carbide, and aluminum nitride, and oxide ceramics such as alumina, zirconia, mullite, beryllia, magnesia, and cordierite. Ceramics can be mentioned. Effects of the Invention According to the present invention, a metallized layer can be formed on a ceramic surface by an extremely simple operation of baking at a lower temperature and then performing a reduction treatment than in the conventional method. The obtained metallized layer has excellent conductivity, extremely high adhesive strength and chemical resistance, and is also excellent in uniformity, particularly surface smoothness and gloss, so it has high commercial value. The ceramics metallized according to the present invention are
Since it has the above-mentioned performance, it can be suitably used for ceramic package, electronic parts such as printed wiring of IC boards, wear-resistant parts using ceramics, heat-resistant parts, etc. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 10 parts by weight of SiO ₂ to 70 parts by weight of copper oxide powder,
20 parts by weight of Nd ₂ O ₃ and 10 parts by weight of balsam are mixed to form a paste, and this is made into a flat square silicon nitride,
A coating of 0.1 g/cm ² was applied to the surface of each sintered body of sialon, silicon carbide, alumina, and zirconia. Next, each sintered body was heated to 1100 ml in air using an electric furnace.
It was baked at ℃ for 30 minutes to form a baked coating layer. The calcined material was then heated in a dryer at 60 DEG C. and then immersed in a 5% solution of dimethylamine borane. This reduced the baked coating layer and formed a metallized layer of metallic copper. Table 1 below shows the electrical resistance values (voltage 1000V) before and after reduction. It is clear that the metallized layer after reduction has extremely good electrical conductivity. Each ceramic having a metallized layer thus obtained and a copper piece were soldered using silver solder, and weighed.
The adhesion strength of the metallized layer was measured using a tensile testing machine with a load of 2 tons and a loading rate of 5 mm/min, and as shown in Table 1, it was found that the adhesion was extremely strong in both cases.

[Table] Comparative Example 1 Each ceramic having a metallized layer was obtained in the same manner as in Example 1 except that Nd ₂ O ₃ was not used, and the adhesive strength of the metallized layer was measured. The measurement results of the electrical resistance value and adhesive strength of the baked layer before and after reduction are shown in Table 2 below.

[Table] From the results shown in Tables 1 and 2, the metallized layer formed by the method using the rare earth compound of the present invention is
It is clear that the adhesive strength is stronger than that without using the rare earth compound.

Claims (1)

[Claims] 1 Consists of (i) at least one of copper carbonate, copper sulfate, copper sulfide, copper oxide and copper chloride, (ii) at least one of SiO ₂ and kaolin, and (iii) at least one of rare earth elements and their compounds. A ceramic metallization method characterized by applying a mixture to a ceramic surface, baking it at 900 to 1300°C in an oxidizing atmosphere, and then subjecting the baked layer to a reduction treatment.