JPH0362674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a silicon carbide ceramic body having a metallized surface suitable for bonding with metal, and a method for manufacturing the same.

[Background of the invention]

By bonding ceramics with metals, new functions not found in ceramics are created, further expanding the range of applications for ceramics. When joining ceramics and metal, it is possible to directly join them using diffusion bonding, etc., but this method generally requires pressure during joining, so it is not suitable for joining complex shapes. do not have. As an alternative method, a method is generally used in which the surface of the ceramic is metallized in advance and then bonded to a metal using silver soldering or soldering. For example, when an electronic component such as a semiconductor package is sealed with a ceramic case, the ceramic case is metallized and then these parts are soldered with silver.

The conventional method for metallizing oxide ceramics such as alumina is to apply a mixed powder of Mn and Mo to the surface of alumina and sinter it in a forming gas at a temperature of 1400°C or higher.
Although there is a Mo-Mn method, it cannot be applied to silicon carbide ceramics.

As a method for metallizing non-oxide ceramics such as silicon carbide and silicon nitride, for example, Japanese Patent Application Laid-Open No. 59-195590
A composition containing at least one metal component among Fe, Ni, Cr, and Mn and at least one component among C, Si, B, and graphite is prepared in the form of powder or foil. This method of metallizing nitride ceramics is characterized by placing the composition on the surface of a nitride ceramic body and melting the composition in a non-oxidizing or weakly oxidizing atmosphere. Not suitable for ceramics.

Furthermore, in the method for metallizing a non-oxide ceramic sintered body disclosed in JP-A No. 59-203780, the surface of the non-oxide ceramic sintered body is coated with aluminum and then an alumina layer is formed. The layers are metallized. This method requires two metallization steps and is uneconomical. Also, JP-A-55-
In No. 51775, high melting point metal powder such as Mo or W is placed on non-oxide ceramics, and metallized by firing under pressure in a non-oxidizing atmosphere. Since this method requires pressurization, it is not suitable for products with complex shapes.

The method for melting the composition is performed at a high temperature to melt the composition, so it is applicable to silicon nitride ceramics, but when applied to silicon carbide ceramics, the bonding reaction with the ceramics proceeds excessively, There are disadvantages in that the brittle compound layer is thick and sufficient metallization strength cannot be obtained, and heat resistance is also low.

On the other hand, as a metallization method for silicon carbide ceramics, W, Mo, Ti,
There is a method of applying powder such as Mn and firing it in a non-oxidizing atmosphere, but this method requires a firing temperature of 1400°C.
Since the temperature is high, above ℃, the thermal stress during bonding is large and a reliable bond cannot be obtained.

[Purpose of the invention]

An object of the present invention is to provide a silicon carbide-based ceramic body having a metallized surface that is suitable for bonding to metal with high bonding strength and has high heat resistance, and a method for manufacturing the same.

[Summary of the invention]

The metallized silicon carbide ceramic body of the present invention is characterized in that a copper or nickel layer is formed on the surface of the silicon carbide ceramic matrix via a mixed layer of chromium silicide and chromium carbide. .

Such metallized silicon carbide-based ceramic bodies are produced by coating the surface of silicon carbide-based ceramics with a paste-like metallic chromium powder, and heating the body to 900°C or higher in an inert atmosphere or an atmosphere with an oxygen partial pressure of 10 ^-2 torr or less.
Heating to 1300°C or less forms a mixed layer of chromium silicide and chromium carbide on the surface of the silicon carbide-based ceramic matrix and an unreacted chromium layer thereon, and after removing the unreacted chromium layer, It can be manufactured by forming a copper or nickel layer on top of the layer.

The metallized silicon carbide-based ceramic body according to the present invention can be produced by metal brazing another metal member to be joined to the metallized surface, that is, the copper or nickel layer formed on the surface.
It can be firmly joined to the metal member.

The present invention will be explained below.

The present inventors applied various metal powders to the surface of silicon carbide ceramics and investigated the state of reaction between the ceramics and metals when the powder was heated to 1000°C in a non-oxidizing atmosphere. discovered a new phenomenon.

In other words, when applying Group A and Group A metals such as Ti, Zr, Nb, and V, the reaction does not proceed at a heating temperature of 1000°C, and the temperature must exceed 1000°C to cause a bonding reaction. It is necessary to raise the heating temperature to near the melting point of the metal. However, it has been found that when the heating temperature is raised to near the melting point, a thick layer of brittle compounds such as carbides and silicides of the metal is formed at the metallized interface, making it impossible to obtain sufficient metallization strength.

When Group A and Group A metals such as Fe, Ni, Mn, and Co are coated, the bonding reaction with the ceramics proceeds excessively at a heating temperature of 1000°C, and the brittle silicide of the metals forms at the bonding interface. Alternatively, it has been found that the carbide layer and free carbon are formed so thick that sufficient metallization strength cannot be obtained.

On the other hand, when applying Cr powder among Group A metals such as Cr, Mo, and W, a thin mixed layer of Cr silicide and Cr carbide may be formed on the matrix of the ceramic. found. This mixed layer of Cr silicide and Cr carbide is strongly bonded to the ceramic, and its thickness is
Unaffected by the thickness of Cr powder, heating temperature is 900~
At 1300°C, it is extremely thin at 1 to 5 μm, which reduces thermal stress and improves metallization strength. On the other hand, a relatively thick unreacted Cr layer containing a portion of chromium oxides such as Cr ₂ O ₃ is formed on the outside of the mixed layer together with the mixed layer, but this unreacted chromium layer has a strong bond with the ceramics. is weak, and its thickness increases approximately in proportion to the thickness of the applied chromium powder. By removing such an unreacted chromium layer before forming the copper or nickel layer, it is possible to prevent it from adversely affecting the bonding strength of the metal members. To remove this unreacted chromium layer, methods such as polishing, removal with a brush, honing, etc. may be used.

Since the mixed layer formed as a result on the ceramic surface does not have sufficient brazing or solderability for joining with other metal members,
After providing a Cu or Ni layer on the surface of the mixed layer, it is desirable to bond it to the other metal member. To form the Cu or Ni layer, methods such as electroplating, chemical plating, vapor deposition, and sputtering can be used. Further, in order to improve the bonding state between the mixed layer and the Cu or Ni layer, it is desirable to perform the diffusion treatment again at a temperature of 500°C to 900°C.

After forming a metallized film of copper or nickel on the surface of silicon carbide ceramics by the above method, it is bonded to other metal members using a brazing material.
A bending strength of Kg/mm ² or more can be obtained, and the heat resistance is also 600℃.
That's all.

The particle size of the chromium powder applied to the surface of silicon carbide ceramics is 500 μm or less, preferably
Should be 100μm or less. If the particle size is larger than this, a portion of the ceramic surface is likely to be not covered with the mixed layer. Also, the coating thickness of chromium powder is
The thickness is preferably 10 μm or more, and if it is too small, the ceramic surface portion is likely to be not covered with the mixed layer, which is not preferred. It is preferable to apply the chromium powder in the form of a paste together with an appropriate paste agent.
Ceramics coated with chromium powder at 900℃~
The heating time to 1300°C is preferably 10 minutes or more and 1 hour or less.

Figure 1 shows the temperature at which silicon carbide-based ceramics coated with chromium powder was heated, and the resultant mixed layer is coated with a Ni plating layer and rediffusion treatment is performed. This is an experimental graph showing the strength of the joint when they are joined by silver brazing. Black circles indicate fractures in the ceramic itself, and white circles indicate fractures at joints. From this, the heating temperature is 900℃~
It can be seen that high-strength metal bonding can be achieved at 1300°C.

[Embodiments of the invention]

Example 1 1 mm thick with about 2 wt% BeO as a sintering aid,
Apply Cr powder made into a paste with dimethyl ethyl cellulose to a thickness of approximately 1 mm on one side of a hot-pressed silicon carbide ceramic plate measuring 20 mm in length and width, and heat it in an Ar atmosphere at 1100℃ for 30 minutes. After firing, it was naturally cooled. As a result, a mixed layer of Cr silicide and Cr carbide with a thickness of about 3 μm was formed on the surface of the ceramic mother plate, and furthermore, an unreacted chromium layer was formed on the surface. Next, the unreacted Kumuro layer was removed with a brush, and a Ni film of about 5 μm thick was formed on the mixed layer on the ceramic surface by electroplating.

The thickness of the metallized film formed by the above method
A tensile test was performed after Cr plates of 500 μm and width of 5 mm were joined by Ag brazing, and a tensile strength of 20 Kg/mm ² was obtained.

Furthermore, as a result of a heat resistance test of this metallized portion, no decrease in bonding strength was observed up to 700°C.

Example 2 2 mm thick with approximately 5 wt% AlN as a sintering aid,
The same paste as above was applied to one side of a hot-pressed silicon carbide ceramic plate measuring 20 mm in length and width.
Apply Cr powder to the entire surface with a thickness of about 0.5 mm, and
After baking at 1050°C for 30 minutes in a vacuum of 10 ^-4 torr, it was naturally cooled. As a result, a mixed layer of Cr silicide and Cr carbide with a thickness of approximately 5 μm was formed on the surface of the ceramic, and an unreacted KUMURO layer was further formed thereon. Next, the unreacted Kumulo layer formed as the outermost layer was removed using an adhesive tape, and Ni was electroplated to a thickness of approximately 5 μm on the mixed layer on the surface of the ceramic.

A stainless steel plate with a thickness of 1 mm and a width of 5 mm was bonded to the metallized film formed by the above method at 900℃ using a Pd-Ag brazing filler metal, and a tensile test was conducted, and the bond strength was approximately 30 Kg/mm ² . is obtained at 700℃
No decrease in bonding strength was observed up to this point.

Example 3 1 mm thick, 3 mm x 50 mm containing approximately 40 wt% ZrB ₂
Approx.
30μm Cr powder was made into a paste and applied to a thickness of about 500μm, which was fired in an Ar atmosphere at 1050°C for 30 minutes and then naturally cooled. Thereafter, the unreacted Kumuro layer on the surface was removed, and Ni plating was performed to a thickness of approximately 3 μm. A Ni wire with a diameter of 1 mm was silver soldered to the Ni-plated surface and used as a heater for ignition.

〔Effect of the invention〕

According to the present invention, a carbide ceramic body having a metallized surface that is firmly bonded to a carbide ceramic body is obtained, and this carbide ceramic body can be bonded to another metal material by brazing or the like to the metallized surface with high bonding strength. can be joined,
Heat-resistant surnames are also great.

[Brief explanation of drawings]

Figure 1 is an experimental graph showing the relationship between the temperature at which a silicon carbide ceramic plate coated with chromium powder was heated and the bonding strength when a copper rod was silver-brazed to the resulting metallized surface. be.

Claims (1)

[Claims] 1. A mixed layer of chromium silicide and chromium carbide is formed on the surface of a silicon carbide ceramic matrix, and a copper or nickel layer is further bonded to the surface of the mixed layer. Features a metallized silicon carbide ceramic body. 2 Apply paste-like metallic chromium powder to the surface of silicon carbide ceramics and heat at 900°C or higher in an inert atmosphere or an atmosphere with an oxygen partial pressure of 10 ^-2 torr or lower.
Heating to 1300°C or less forms a mixed layer of chromium silicide and chromium carbide on the surface of the silicon carbide-based ceramic matrix and an unreacted chromium layer thereon, and after removing the unreacted chromium layer, 1. A method for producing a metallized silicon carbide ceramic body, comprising forming a copper or nickel layer on the layer.