JPH03208877A - Metallizing method for oxide ceramics - Google Patents

Abstract

PURPOSE:To improve adhesivity by coating an oxide ceramics sintered body with a 1st layer consisting of W and glass and a 2nd layer consisting of Ni and Cu or the compd. thereof and then burning the sintered body at and in a specific temp. and atmosphere. CONSTITUTION:The oxide ceramics sintered body, consisting of Al2O3, etc., is coated with the paste prepd. by kneading a powder mixture composed of 70 to 99wt.% (hereafter %) W powder having <=10mum particle size and 30 to 1% glass powder having 1100 to 1300 deg.C m. p. and <=10mum grain size with an org. vehicle and thereafter, the coating is dried to form the 1st layer 301. The 1st layer is then coated with the paste prepd. by combining one kind of Ni, Ni oxide and Ni salt having <=10mum grain size and one kind of Cu, Cu oxide and Cu salt to 45/55 to 10/90 Cu/Ni and kneading the mixture with an org. vehicle at the thickness to of to/tw<=1 and thereafter, the coating is dried to form the 2nd layer 302. The sinthed body is then burned in the mixed atmosphere of 1150 to 1350 deg.C adjusted to 1<H2/H2<100000. The metallized oxide ceramics having excellent vacuum sealability, brazability and joint strength is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for metallizing ceramics, and more particularly, to a method for metallizing oxide-based ceramics that has excellent vacuum sealing properties, brazing properties, and bonding strength.

[Conventional technology]

Examples of devices that utilize the bonding of metal and oxide ceramics include electron tubes such as magnetron insulators for microwave ovens and vacuum switch envelopes.

When using metal-ceramic bonding for these purposes, the bonding interface must maintain vacuum-sealing properties, and bonding methods that meet this condition include: - For boat fishing, metallizing ceramics; A method is used in which the ceramic is brazed to a mating metal after metallization.

Conventionally, high melting point metal methods have been widely used as a metallization method. The high melting point metal method involves mixing high melting point metal powder such as molybdenum or tungsten with manganese powder, applying the mixed paste in an organic vehicle to the surface of oxide ceramics, and firing it to form a molybdenum layer or forming a tungsten layer,
After that, nickel plating is applied to coat the surface with nickel, and then the target metal is brazed. Without this nickel coating, the flowability of the brazing filler metal is poor. Therefore, coating the surface with nickel is essential for improving brazing properties. However, it is very difficult to perform nickel plating on a metallized surface using the high melting point metal method, and various treatments are required. That is,
The surface of the metallized layer created using the high melting point metal method is partially covered with glass, so deglassing is required.
In addition, it is necessary to perform acid treatment, activation treatment with palladium chloride, etc. for surface modification. As described above, the high melting point metal method is a metallization method with excellent vacuum sealability, but it has the disadvantage that the process is long and the manufacturing cost required for this process is extremely high.

The present inventors investigated a method of omitting the latter of two major steps, the metallization step and the Ni adhesion step.

This is because while the former is the essential process of metallization, the latter is an additional process called Ni plating, but it requires a lot of equipment for the preliminary treatment process, plating equipment, water treatment equipment, etc. It is. Hereinafter, the metallized main body made of molybdenum or tungsten will be referred to as the lower metallized layer, and the layer above it, which is mainly composed of Ni, will be referred to as the Ni upper layer. It is very advantageous to reduce the cost of the entire metallization by reducing the process only for forming the Ni upper layer and forming the Ni layer. From this viewpoint, the present inventors formed the Ni upper layer. We considered a method of omitting all the various steps involved.

To omit various steps for forming the Ni upper layer,
-N after forming a metallized layer by high melting point metal method
A two-time firing method can be easily considered in which a paste containing i mixed with an organic vehicle is printed and fired again to form a Ni layer. However, with this method, firing must be performed twice, and even if the plating equipment can be omitted, the firing process is still performed twice.
This is not desirable in terms of strength since the lower layer is subjected to thermal cycles during the firing process twice.Therefore, the present inventors decided to form the metallized lower layer and the Ni upper layer. We focused on doing this at the same time.

First, we devised a method in which a paste made by mixing powders of molybdenum and manganese in an organic vehicle was applied to the ceramic surface, and then a Ni paste was printed on the top surface and fired at the same time. However, when actually conducting an experiment,
The result was that Ni was slightly dissolved in molybdenum, and the dissolved Ni significantly accelerated the sintering rate of molybdenum, making it impossible to obtain a sound metallized layer. As described above, simply applying two coats of high melting point metal paste and Ni paste does not form a sound metallized layer.

Furthermore, although the process of two coats and simultaneous firing is often carried out in the field of metallization, the purpose of the present invention is to form the previously defined lower metallized layer and upper Ni layer in one firing. different.

For example, in the method described in Japanese Patent Publication No. 36-6542,
The first layer is a mixed powder of a high melting point metal and ceramics, and the second layer is a metal layer made of a high melting point metal, and this method is related to improving the formation of the metallized lower layer in the present invention. This does not mean that the various steps for forming the Ni upper layer are omitted, and is completely different from the gist of the present invention. In addition, in this method, the metals of the first layer and the second layer are the same N
o, and the conditions for simultaneous firing of the same metal are no different from the conditions for firing only one layer.
Publication No. 213688 discloses a method of reducing the resistance value of the metallized portion by using oxide powder of a high melting point metal in the first layer and using a high melting point metal in the second layer.
Like the invention described in Japanese Patent Publication No. 36-6542, this also relates to the formation of a metallized lower layer, and is completely different in spirit from the present invention, which includes plating. That is, the metallized surface obtained by the method described in JP-A-58-213688 is not suitable for brazing, and various steps are required to form a Ni upper layer in order to enable brazing.

[Problem to be solved by the invention]

As mentioned above, in order to metallize oxide ceramics and obtain brazing properties, the surface must be coated with a metal that has brazing wettability equivalent to nickel, and when used as an electron tube material. must have excellent vacuum sealability. However, the conventional two-step process of forming a lower metallized layer and then forming an upper layer has the drawback of high manufacturing costs.

Therefore, it has been desired to develop a metallization method that reduces manufacturing costs, has vacuum sealing properties, brazing properties, and high strength.

The present inventors have filed a patent application for an invention in which the optimum conditions for a two-coating method are a constituent feature, with the aim of fundamentally improving the formation of a lower metallized layer and an upper Ni layer (Japanese Patent Application No. 1-51271). (hereinafter referred to as the "prior invention").

This prior invention is compared to the prior art. ■ Superior brazing performance ■ Superior vacuum sealability ■ Manufacturing costs are approximately halved ■ No inferior bonding strength It has the following characteristics.

However, by using the basic process shown in the prior invention and changing the materials, manufacturing conditions, etc.,
There was a possibility that the characteristics of ~■ could be further improved. That is,
Both the Mo-Mn method and the co-firing method proposed by the present inventors have had the problem of poor solder wettability because the surface is covered with Ni. While Co and Sn have very good solder wettability,
Ni is not very good.

The present invention aims to improve the solder wettability (or solderability) by adding copper, or its salt, or oxide, instead of using nickel alone as the upper layer material.

[Means to solve the problem]

The gist of the present invention is to add 70 to 99% by weight of tungsten powder with an average particle size of Ion or less and a tungsten powder with a melting point of 1100 to 1300°C and an average particle size of 10N or less on the surface of an oxide ceramic sintered body. A paste made by kneading a mixed powder consisting of 30 to 1% by weight of glass powder in an organic vehicle was
After coating to a thickness tw of n or less, dry to form a first layer, and then on the first layer, any one of nickel, nickel oxide, and nickel salt with an average particle size of 10n or less Then, a paste made by kneading a powder of copper, copper oxide, or copper salt with an average particle size of IOn or less in an organic vehicle is made so that the thickness to is equal to or less than the above tw. After applying it, dry it and apply the second
A layer is formed and then at a temperature range of 1150-1350°C and 1 <H! The present invention provides a method for metallizing oxide-based ceramics having excellent vacuum sealing properties, brazing properties, and bonding strength, which is characterized by firing in a mixed atmosphere adjusted to /H,0<100000.

[For production]

The present inventors believe that the manufacturing cost of the conventional refractory metal method is lower than that of
Consideration of a metallization method for alumina ceramics that has significantly lower manufacturing costs and that allows the finished product to maintain vacuum sealing and brazing properties equal to or better than those produced using the refractory metal method. I've been repeating it.

The steps of the refractory metal method, which has traditionally been used in various fields, are shown below. First, a high-melting point metal such as molybdenum or tungsten and manganese are made into a paste, and the paste is applied onto the top surface of the alumina ceramic. The furnace is kept in a controlled atmosphere where manganese is oxidized but molybdenum is not oxidized. A specific example is N*:Hz
-9: 1. The atmosphere has a dew point of 40°C and a temperature of about 1450°C. The molybdenum sinteres at this temperature, forming a metal network and forming the skeleton of the metallized layer.

However, immediately after the formation of this molybdenum layer, plating is almost impossible, so degreasing, deglassing treatment, etc.
The reason why such treatments such as acid treatment and activation treatment are carried out is because the metallized surface is covered with glass or the high melting point metal is thought to be thinly oxidized. The only drawback of the refractory metal method is thus that after the formation of the layer of molybdenum, lengthy steps such as pretreatment, plating, etc. are required to form a nickel layer on the surface.

Therefore, the present inventors conducted experimental research focusing on the fact that if the molybdenum undercoat is applied, the upper surface is overcoated with nickel, and then firing is performed, the process can be completed only once. However, in this case, nickel diffuses into molybdenum, and molybdenum and nickel form a eutectic and either melt or oversinter, making it impossible to obtain a sound metallized layer.

This is due to the fact that nickel was dissolved in molybdenum during firing, and the self-diffusion coefficient of molybdenum increased. In other words, the selection of the metal for the first layer is a very important item in order to coat with nickel in one firing.

Therefore, the present inventors have found that if a paste such as molybdenum or tungsten is used as an undercoat, and then a metal with a self-diffusion coefficient in the range of 0.2 to 0.6 times the self-diffusion coefficient of the metal is overcoated on top of the undercoat metal, the result will be good. It was discovered that there is a possibility of metalization. As a result of subsequent research, it was discovered that nickel was suitable as one of the outermost layer metals for brazing, and when coating with nickel, it was confirmed that tungsten was the best metal to use in the first layer. Ta.

At the same time, we discovered that the above-mentioned problems could be solved by applying a uniform mixture of tungsten and glass to the surface of oxide-based ceramics, and then applying nickel to the top surface. Therefore, the present inventors applied for a patent as described above for a method of coating nickel in one firing by using tungsten for the first layer and nickel for the second layer.

However, like the conventional Mo-Mn method, this metallization method has poor solder wettability because the surface is covered with nickel, meaning that when soldering is performed, the solder spreads uniformly over the entire surface. There were many cases where people did not want to do so.

Therefore, the inventors of the present invention have investigated various ways to improve this situation, and have found that it is better to use only nickel as the metal for the overcoat layer (in addition to copper, copper oxide, or copper salt). We found that the solder wettability was significantly improved by adding one type of metal to the second layer.However, the optimal manufacturing conditions are different compared to the case where nickel is applied as the second layer.Also, when nickel is used as the second layer metal, It has been found that when used, the bonding strength exceeds that of the prior invention, depending on the coating thickness.

The present inventors formed the Ni upper layer using nickel, nickel oxide,
One type of nickel salt and one type of copper, copper oxide, and copper salt
By replacing it with a mixture of seeds and reconsidering the optimal conditions such as firing conditions, we have completed a product that is equivalent to the prior invention in terms of vacuum sealability and brazing performance, and superior in bonding strength.

The mechanism of metallization in the metallization method of the present invention is as follows.

First, as shown in the schematic diagram of FIG. 2(a), a mixed powder consisting of tungsten powder and glass powder is applied to the surface of an alumina ceramic sintered body 2, which is one of the oxide ceramics, using an organic vehicle. A paste formed by kneading is applied and then dried to form a first layer 301. The average particle size of the tungsten powder and the glass powder (hereinafter simply referred to as particle size unless otherwise specified) is adjusted to be 10 nm or less. The melting point of glass is 110 as described below.
A healthy metallized structure was not formed unless the temperature was in the range of 0 to 1300°C. As an example, AjtOs-Mn
O-5i (h series) can be used. Also, as an example of an organic vehicle, a mixture of an organic binder such as ethyl cellulose and an organic solvent such as terpineol to an appropriate viscosity can be used. A paste made by kneading a mixture of one of nickel, nickel oxide, and nickel salt with one of copper, copper oxide, and copper salt in the organic vehicle is applied to the upper surface of the layer 301. After that, it is dried to form the second layer 302. Nickel, nickel oxide, nickel salt, and copper, copper oxide,
Any copper salt may be used as long as the particle size is adjusted to 10 nm or less, and FIG. 2 (b) schematically shows these.

After forming the first layer 301 and the second layer 302 in this way, the ceramic sintered body 2 was heated to a temperature of 1150 to 1350''C.
The firing is carried out within the following atmospheric conditions. During this firing, the tungsten powder of the first layer 301 is sintered to some extent, as shown in the schematic diagram of FIG. On the other hand, the glass powder in the paste melts, a part of which flows onto the surface of the ceramic sintered body 2 and reacts with the alumina.

The remaining glass fills the voids in the tungsten without any gaps, forming a tungsten and glass mixed layer. On the other hand, nickel, nickel oxide, nickel salt, copper, copper oxide, and copper salt in the second layer 302 are reduced to a metal solid solution and sufficiently sintered in the firing atmosphere, and cover the tungsten layer, and the nickel itself becomes nickel. and form a solid solution layer of copper. Hereinafter, this will be referred to as a solid solution layer. Figure 1 shows a cross section of the metallized layer 3 formed on the surface of the ceramic sintered body 2 in this way. A mixed layer 31 and a solid solution layer 32 are formed on the upper surface of the mixed layer 31 to constitute the metallized layer 3. In this case, tungsten can be dissolved in the solid solution layer 32 up to its solid solubility limit, but it does not affect the brazing properties.
A strongly bonded metallized layer 3 is formed. After cooling, alumina and glass become a continuous phase, and tungsten and glass firmly adhere due to the anchor effect. In this way, alumina and tungsten are bonded to each other through glass, and tungsten and nickel are bonded to each other by mutual diffusion, and a metalized alumina body 1 is completed.

The glass powder is limited to one having a melting point of 1100 to 1300°C. This glass is Aj, 03-1'lln
0-5to type is preferable, but this is not the case as long as it has the above melting point.

That is, if the melting point is less than 1100° C., the strength of the glass itself will be low, and the glass will flow too much, resulting in a significant decrease in strength after metallization. On the other hand, if the melting point exceeds 1300° C., the fluidity of the glass deteriorates, and the voids in the tungsten are not completely filled, making it impossible to obtain sufficient vacuum sealing properties.

Further, the tungsten grains are limited to those having a grain size of 10 nm or less. Outside this range, the variation in the distance between tungsten grains becomes too large, and the glass moves to the area where the tungsten grain distance is narrow due to capillary action, making it impossible for glass to exist in the area where the tungsten grain size is wide, resulting in vacuum sealing. The glass particle size is limited to less than Ion, and the reason for this is the same as the reason for limiting the tungsten particle size described above.

That is, when glass having a particle size of more than 110 Ir is melted, the glass is absorbed into the area where the tungsten particle size is small, and the area where the glass was present becomes a void.

The mixing ratio of tungsten powder and glass powder is limited to 70 to 99% by weight of tungsten and 30 to 1% by weight of glass. If this ratio deviates to the side with more tungsten,
The absolute amount of glass is too small, the glass cannot fill the tungsten network, and the vacuum sealability cannot be guaranteed, on the contrary.

This is because if the amount of tungsten is shifted to the side with less tungsten, the tungsten cannot form a network and sufficient strength cannot be obtained.

Nickel, nickel oxide, nickel salt, and copper, copper oxide, and copper salt are also limited to 10#m or less. If this value is exceeded, sintering will not proceed sufficiently and the surface of the mixed layer 31 (tungsten-glass layer) will not be completely covered, resulting in poor brazing properties.Also, the number of contact sites between tungsten and the top coat metal will decrease, resulting in stronger In addition, nickel, nickel oxide, nickel salt, copper, copper oxide, and copper salt are all reduced to metal when fired in the atmosphere described below, and among these types, significant No difference observed.

Further, the amount of Cu added in the top coating component is Cu:Ni
It is desirable to set the weight ratio to be less than 45:55, and it is also desirable to have a weight ratio of 10:90 or more. If the amount of Cu is more than 45% of the total metal amount, the metal of the solid solution layer If the ratio is less than 10%, the solder wettability will not be improved.The most preferable ratio is Cu:Ni by weight.
= 15:85.

The firing temperature is limited to 1150-1350°C. This is a shift to a lower temperature of 50°C than in the case of the sintering of the invention described above, but this is because the sintering rate of tungsten is lower than that of the case where Ni is dissolved in tungsten. This is because it is faster when the metal is in solid solution. 11
If it is below 50°C, the amount of reaction between alumina and glass is small (and the fluidity of the glass is also poor, and the sintering of tungsten is insufficient, so it is thought that sufficient strength and vacuum sealability cannot be obtained. 1350 When the temperature exceeds °C, the tungsten is oversintered and there are fewer voids for the glass to fill, which reduces the anchoring effect between the glass and tungsten and reduces the strength.For the firing atmosphere, the ratio of hydrogen to water vapor (Hz /HzO) is greater than 1 and less than 100,000 (1<
(1ml/1.0)<100000).

When the value is less than 1, tungsten is oxidized. 1
If it is more than ooooo, the glass is reduced and metal is precipitated, and the alumina becomes more discolored. In this way, if the ratio of hydrogen and water vapor is within a predetermined range, Hz * Ar
For example, a gas flow with a dew point of 20'C and Ht:Nt = 10:90 is desirable, in which an inert gas such as +16 can be mixed.

The characteristics of the structure after metallization under the conditions of the present invention will be described below.The present invention is particularly characterized by the solid solution layer. The first feature requires that the following relationship be established between the solid solution layer thickness and the tungsten-glass mixed layer thickness. That is, when the thickness of the mixed layer 31 is tw and the thickness of the solid solution layer is to, the relationship tw≦5On to/lW≦1 needs to be established.

When tw exceeds 50n, blisters may occur on the surface of the metallized layer. When to/1w exceeds 1,
Thermal stress due to the difference in thermal expansion between the solid solution layer and tungsten increases, and the bonding strength decreases.

The second feature is that since the solid solution layer paste is applied by screen printing, the thickness of the solid solution layer in the product can be easily increased compared to the plating method, which is advantageous in terms of heat resistance, etc. It is a certain thing. In the conventional Metsuki method, the second
Attempts to apply a metal layer equivalent to the above layer are very costly, and the thickness usually has to be 2 to 4 μm, which is extremely disadvantageous from the viewpoint of heat resistance.In the present invention, the process of applying a solid solution layer is Therefore, the cost increase due to thickness is small.

Next, in the case of the present invention, the tungsten of the first layer dissolves into the solid solution layer of the second layer due to simultaneous firing.

As described above, the present invention also has organizational features. In particular, one of the major characteristics is that tungsten is dissolved in solid solution in the solid solution layer, and this fact can be easily detected by EPMA or the like.

Although the ceramics used in the above experimental examples were alumina-based, various experiments were also conducted on other types of ceramics. As a result, Murai) (2MtOs・2
Equivalent vacuum sealability and strength were obtained with SiO, steatite (MgO・5i(h), forsterite (2MgO・Stow), and cordierite (2MgO・2AjzOz・5SiOi). This shows that the metallization method of the present invention is particularly effective for ceramics containing components that easily react with the glass component in the forming paste.

That is, the present invention is particularly effective for ceramics containing oxides. Among the above-mentioned ceramics, steatite and forsterite have a heat resistance temperature lower than that of M2O3, and the conventional metallization method of firing at around 1450°C had the disadvantage that the characteristics of the ceramic deteriorated significantly, but according to the present invention, the heat resistance temperature is lower than that of M2O3. Despite the low firing temperature, these low heat-resistant temperature ceramics can be sufficiently metalized.

〔Example〕

Example 1 A copper pipe 6 is joined as shown in FIG. 5 to a cylindrical body 20 which is a ceramic sintered body and has an inner diameter of 12 mm x outer diameter of 16 mm and a height of 10 mm as shown in the perspective view of FIG. 4. The present invention was carried out at the same time.

The cylindrical body 20 has a diameter of M, 0. The upper end 20a of this cylindrical body 20 is first made of alumina with a particle size of 5%.
Ajz03-MnO-5iO2 adjusted to n or less = 1
Ajg03JInO-SiOg with a weight ratio of 0:45:45
A mixed powder obtained by mixing glass powder and tungsten powder in the ratio shown in Table 1 was kneaded in an organic vehicle, and the resulting paste was applied by screen printing.

After applying the paste, heat it in the oven at 200°C
After drying for 0 minutes, the first layer 31 is dried as shown in FIG.
1 was formed. Then, on the surface 311a of the first layer 311,
A mixed powder of nickel powder and copper oxide powder adjusted to a particle size of 5 nm or less was mixed with nickel powder: copper oxide powder = 80:20) in the organic vehicle described above, and the resulting paste was applied by screen printing. After coating, a second layer 321 was formed by drying in an oven at 200° C. for 120 minutes. The thickness of both the first layer 311 and the second layer 321 is 2
It is on. After that, 90% nitrogen by volume with a dew point of 20°C.
, a heating rate of 10″C in a mixed gas flow containing 10% hydrogen by volume.
/min to the temperature shown in Table 1 and held for 60 minutes.

Next, it was cooled at 10° C./min to form a metallized layer 30, and an alumina body 10 was obtained.

A copper tube 6 was bonded to this alumina body IO as shown in FIG. 5, and the vacuum sealability and bonding strength were measured.

The bonding with the copper tube 6 is performed using a brazing material 5 (in this embodiment, JIS Z 3261BA) between the metallized layer 30 and the copper tube 6.
g-8) was interposed and brazed in a hydrogen atmosphere to obtain a joined body. After obtaining the bonded body, an adhesive that maintains sufficient sealing properties is used on the bottom surface 20b of the alumina body,
A steel jig was installed.

The vacuum sealability was determined by measuring the amount of leakage from the tip of the copper tube 6 using a helium leak detector. The evaluation criteria is that the amount of helium leak is I x 10 - IlITorr·j! /
Those exhibiting a sealing property of sec or less were passed.

The bonding strength is determined by fixing the iron jig and pulling the copper pipe 6 upward.
It was measured. Table 1 shows an example of the results of an investigation using the mixing ratio of the glass powder and tungsten powder and the firing temperature as parameters. Firing temperature 1150-1350℃
, the weight ratio of tungsten and glass is 70:30-99:
A bonded body was obtained that maintained good properties between 1 and 1.

Next, the steel pipe joints shown in Fig. 5 were heated at 50°C to 600°C.
A heat cycle test was conducted in which the sample was heated to 50°C, maintained at that temperature for 10 minutes, and then cooled to 50°C. The heating rate is 34
C./min, and the temperature drop rate was 37.degree. C./min, and the above-mentioned changes in vacuum sealability and tensile strength were investigated by repeating this heating and cooling process. As a result, in the conventional high melting point metal method, the vacuum sealability deteriorated after 10 thermal cycles, and the tensile strength also decreased to 100 kgf or less.

On the other hand, the device based on the present invention has vacuum sealability lXl0-'°Torr1/sec even after 10 thermal cycles.
The following conditions were ensured, and the tensile strength was 350 kgf or more (copper tube 6 was destroyed).

Example 2 Next, in order to investigate the influence of the melting point of glass, the mixing ratio of tungsten powder and glass powder was kept constant at 80 = 20 in Example 1, the melting point of the glass powder was adjusted, and other The metallized layer 30 was formed under the same conditions as in Example 1, and the vacuum sealability and bonding strength were measured.

Table 2 shows an example of the results of the investigation. In order to obtain good properties, it is necessary to maintain a firing temperature of 1150 to 1350°C and a glass melting point of 1100 to 1300°C.

Example 3 Next, the influence of the particle size of each powder such as tungsten, glass, nitrogen, copper (CutO was used in this example), etc. was investigated. The characteristics of each combination of tungsten, glass, nickel, and copper powders whose particle sizes were adjusted to 5 and 10.2 On were investigated. The mixing ratio is
The ratio of nickel powder to copper dioxide powder was 80:20, and the other conditions were the same as in Example 1 above.

Table 3 shows an example of the results of the investigation, and the evaluated characteristic values were the vacuum sealability and bonding strength described above. It has been found that in order to obtain good characteristics, it is necessary to adjust the tungsten, glass, nickel, and copper powders to 10 or less.

Example 4 Next, a test was conducted under the same conditions as in Example 1, with the thicknesses of the first layer 311 and the second layer 321 changed as shown in Table 4.

Table 4 shows the results of the investigation. When to/1w becomes larger than 1, the strength begins to decrease.

Example 5 Table 5 shows a test in which the mixing ratio of tungsten powder and glass powder was kept constant at 90:10, the other conditions were the same as those in Example 1, and only the ratio of nickel and copper was changed. It was done.

The sum of the metal components of the topcoat paste was taken as 100%.

LO/1w in this case was set to 0.6.

Solder wettability was determined by using solder with Sn:Pb=62:38% by weight and looking at the spreadability on the metallized surface.

Those with instant relief on the entire surface were considered to be good.

gf ◎O: maintains vacuum sealing properties and has a strength of 350 kgf [Effects of the invention] As explained above, according to the present invention, the equipment cost when metalizing an oxide ceramic sintered body is lower than that of the conventional high melting point. Although the cost has been reduced by 50% compared to the metal method, it is now possible to manufacture products with properties that are not inferior to those obtained by conventional methods. Furthermore, solder wettability is significantly improved compared to the method using nickel as the second layer metal. Furthermore, the present invention can also be applied to ceramics with a low melting point, which has been considered difficult to produce using conventional high-melting point metal methods.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a metallized layer formed according to the present invention, and Fig. 2 shows a state in which paste is applied to the surface of an alumina ceramic sintered body. Fig. 2 (a)
is a cross-sectional view, FIG. 2(B) is a schematic diagram, FIG. 3 is a schematic diagram showing the state in which the paste applied to the surface of the alumina ceramic sintered body is baked, and FIG. 4 is a concrete implementation of the present invention. Examples are a perspective view of a cylindrical alumina ceramic sintered body, FIG. 5 is a sectional view showing a state in which a steel pipe is joined to the alumina body shown in FIG. 4, and FIG. 6 is a perspective view of the alumina body shown in FIG. FIG. 3 is a cross-sectional view showing a metallized layer. 1.10... Alumina body, 2.20... Alumina award ceramic sintered body, 3.30... Metallized layer, 3
DESCRIPTION OF SYMBOLS 1...Tungsten-glass layer, 32...Solid solution layer, 301,311...1st layer, 302.321...
2nd layer, 5... Brazing metal, 6... Steel pipe. Figure Figure 2 ÷ (a) (b) Figure 5 Figure 6

Claims (1)

[Claims] On the surface of the oxide-based ceramic sintered body, particles with an average particle size of 10
A paste with a thickness of 50 μm or less is made by kneading a mixed powder of 70 to 99% by weight of tungsten powder with a diameter of 1100 to 1300°C and 30 to 1% by weight of glass powder with a melting point of 1100 to 1300°C and an average particle size of 10 μm or less in an organic vehicle. After coating, drying to form a first layer, and then on the first layer, any one of nickel, nickel oxide, and nickel salt with an average particle size of 10 μm or less and an average particle size of 10 μm or less. is 1
After applying a paste made by kneading a powder of copper, copper oxide, or copper salt of 0 μm or less in an organic vehicle so that the thickness to is equal to or less than the above tw, dry it. to form a second layer, and then at a temperature range of 1150 to 1350°C and 1<H_
Vacuum sealing properties and brazing properties characterized by firing in a mixed atmosphere adjusted to 2/H_2O<100000,
and a method of metallizing oxide ceramics with excellent bonding strength.