JPH0649620B2 - Method for joining ceramic member and metal member - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for joining a ceramic member and a metal member, and more specifically, a novel joining method which has high joining strength and does not cause cracks in the ceramic member. Regarding

[Technical Background of the Invention and Problems] Members made of various ceramics such as silicon nitride, silicon carbide, and alumina have been widely used as structural members and various functional members by taking advantage of the unique characteristics of each. There is. In many cases, the ceramic is used alone.

However, if it is possible to join these ceramic members with metals having other properties that ceramics do not have, it is thought that the obtained members will be usable in a wider field as members with new functions. To be

In such a member, when it is a structural component, the bonding strength between the ceramic member and the metal member is required to be sufficiently high, and when it is a functional member, the bonding interface between the ceramic member and the metal member is required. Therefore, it is required to have continuity.

However, in general, ceramics and metals are materials with different atomic bonding states, and their chemical properties such as reactivity; thermal expansion coefficient; In the above, it is difficult to form a highly reliable metallurgical bonding state at the bonding interface between both members.

By the way, conventionally, the following various methods have been known as a metallurgical joining method of a metal member and a ceramic member. For example, firstly, a mixture of powder containing Mo-Ti-W as a main component and an organic binder is applied to the surface of the ceramic member to be joined to the metal member and heated to 1400 to 1700 ° C in a humidified atmosphere. To form a layer generally called metallizing, then, after Ni plating is applied on the metallizing layer, a metal member (for example, Cu base material) is applied to the Ni plating.
This is a method of joining with Pb-Sn solder or the like.

Such a joining method is often used in an electronic component when joining a ceramic member as an insulator and a Cu member as a conductor.

The second is a method of joining the metal member and the ceramic member using an alloy whose main component is a noble metal such as Au and Pt, that is, a metal having a small affinity with oxygen.

Thirdly, there is a T at the joint between the metal member and the ceramic member.
This is a method in which an active metal such as i, Nb, or Zr or an active metal hydride that is converted into an active metal by heat treatment is interposed, and then both are joined at high temperature and high pressure.

However, the above method has a drawback that it requires many steps and is complicated.

Although the above method can be joined in a simple process, since an expensive precious metal is used, the economical merit is extremely small, and high pressure is required so that the metal member and the ceramic member are sufficiently brought into contact with each other. In the above method,
Although strong joining is possible due to the effect of the active metal, it is not preferable to apply it to parts and the like that are unfavorable to deformation because high joining pressure is required as in the above method.

In order to solve such a problem, US Pat.
No. 3 specification discloses the following joining method.
In other words, the method is that active metals such as Ti and Zr and Cu and N
Alloys with transition metals such as i and Fe have a melting point (Ti; 1720 ℃, Zr; 1860 ℃) of the active metal alone and Cu, N in the eutectic composition region.
Focusing on lowering the melting point by several hundreds of degrees Celsius compared to the melting points of i and Fe alone (1083 ° C, 1453 ° C, 1534 ° C, respectively), an active metal is interposed between the transition metal member and the ceramic member, The joining member is heated to a temperature higher than the melting point of the alloy of the transition metal and the active metal and lower than the melting point of the transition metal, and the atoms of the transition metal and the active metal are mutually diffused to form an alloy, and this alloy forms a transition metal member. This is a method of joining with a ceramic member.

In the case of this method, at the time of joining, the joining portion is filled with a melt of an alloy of a transition metal and an active metal, which wets the metal member and the ceramic member, so that almost no pressing force is required to bring the members into contact with each other. However, both members are firmly joined by the action of the active metal.

However, a drawback of this method is that cracks frequently occur in the ceramic member during the process of cooling the obtained ceramic-metal bonding member. This is a phenomenon based on the thermal stress generated between the ceramic member and the metal member.

For example, when the ceramic member is alumina or silicon nitride, the coefficient of linear thermal expansion of each is 8.8 × 10 ^{-6 /} ° C, 2.5 ×
It is 10 ^-6 / ° C, which is about one digit smaller than that of Cu, Ni, Fe, etc., and the thermal stress generated at the joint between the two becomes large.

Moreover, the thermal stress is the temperature at the time of joining and the temperature at the time of cooling (room temperature).
The larger the difference is, the greater the difference. Therefore,
In order to reduce the thermal stress, it is required to lower the temperature at the time of joining, which requires the use of a brazing material having a low melting point at the time of joining.

As a method based on this viewpoint, a brazing filler metal containing an active metal and a thin ductile metal such as Cu, Cu alloy, or Al is interposed between the brazing filler metal and spot welding the brazing filler metal and the metal member. A method for joining a ceramic member and a metal member using an integrated joining material (Japanese Patent Laid-Open No. 56-163093) has been proposed. Also, a joined body has been developed in which a brazing material containing an active metal is diffused into both the ceramic member and the metal part.

However, these methods cannot be said to be industrial because they require complicated steps and long-time heat treatment, and are not always effective in alleviating thermal stress between the ceramic member and the metal member.

As a method for achieving stress relaxation when the above method is applied, a soft metal layer is interposed between a ceramic member and a metal member, and thermal stress is relaxed by its plastic deformation and elastic deformation (JP-A-56- No. 41879), a method of interposing a layer of a material having a linear expansion coefficient between the ceramic member and the metal member (see Japanese Patent Laid-Open No. 55-113678), or a line extending from the ceramic member to the metal member. There is disclosed a method (see JP-A-55-7544) in which a plurality of layers whose expansion coefficient changes from small to large are sequentially laminated and interposed.

However, in the case of the above-mentioned joining method using a brazing filler metal containing an active metal, the molten brazing filler metal often protrudes from the joint due to the pressure applied to the joint surface. If the amount of the molten brazing filler metal that has overflowed increases, cracks may occur in the ceramic member due to thermal stress due to the difference in thermal expansion coefficient between the ceramic member and the brazing filler metal during the solidification cooling process. In order to prevent this phenomenon, the optimum amount (thickness) of the brazing material that does not protrude and is necessary for the brazing material to wet the entire surface of the joining member should be determined. It is very difficult to determine the optimum amount of brazing filler metal depending on the conditions such as joining temperature and atmosphere.
Also, a method of mechanically preventing the protrusion is considered, for example, a method of sealing the outer circumference of the joint part with a material having poor wettability with the brazing material, but this method requires selection of a material having poor wettability. Not only is it difficult, but it also complicates the joining process, which is difficult to call a realistic method.

For this reason, there is a strong demand for a method that can relax the thermal stress, prevent the molten brazing filler metal from protruding, and easily join the ceramic member and the metal member with high joining strength.

[Object of the Invention] The present invention is a method of joining a ceramic member and a metal member, which can firmly join the ceramic member and the metal member without applying pressure, and which does not cause cracks in the ceramic member during the cooling process. For the purpose of providing.

[Summary of the Invention] The inventors of the present invention have conducted extensive studies on a method of joining a whole of a ceramic member and a metal member with a stress buffer member and joining them together with a brazing material. It was found that the above object was achieved and the product was sold when the thickness was controlled as described below, and the method of the present invention was developed.

That is, the method of joining the ceramic member and the metal member of the present invention, the thickness of the ceramic member and the metal member 0.2mm
The stress buffer member described above is inserted, and a silver layer having a thickness of 1 to 19 μm and an active metal layer having a thickness of 0.5 to 9 μm are provided between the ceramic member and the stress buffer member and between the metal member and the stress buffer member. And a thin layer A having a total thickness of 2 to 20 μm or a silver layer having a thickness of 1 to 19 μm, an active metal layer having a thickness of 0.5 to 9 μm, and a copper layer having a thickness of 8 μm or less and having a total thickness of 2 to After the thin layer B having a thickness of 20 μm is interposed, the whole is heated.

First, examples of ceramic members to which the method of the present invention can be applied include oxide ceramic members such as Al ₂ O ₃ and ZrO ₂ ; carbide ceramic members such as SiC and TiC; Si ₃ N ₄ , Examples thereof include nitride ceramics members such as AlN. Also, as the metal member,
Examples thereof include members made of metals such as Fe, Ni, Co, Ti, Mo, W, Nb, Ta and Zr, or members made of an appropriate alloy of these metals.

In the method of the present invention, first, a stress buffering member having a thickness of 0.2 mm or more is inserted between the ceramic member and the metal member. When the thickness of this member is less than 0.2 mm, the thermal stress generated between the ceramic member and the metal member cannot be effectively absorbed, and cracks start to occur frequently. Preferably, 0.
2 to 2.0 mm. The material for forming the stress buffering member is, for example, a soft metal such as Al or Cu, which can absorb the thermal expansion difference between the ceramic member and the metal member by plastically deforming or elastically deforming, or a wire. The coefficient of expansion is an intermediate value between the ceramic member and the metal member, for example M
Examples thereof include materials such as o, W, and Ti, and materials for the composite layer whose linear expansion coefficient is appropriately adjusted.

Next, a thin layer A or a thin layer B described later is interposed between the ceramic member and the stress buffer member and between the stress buffer member and the metal member.

First, the thin layer A is a silver layer having a thickness of 1 to 19 μm and a thickness of 0.5 to 9 μm.
m active metal layer and the total thickness is 2 to 20 μm.
m layers. The thin layer B is a layer having a thickness of 1 to 19 μm, an active metal layer having a thickness of 0.5 to 9 μm, and a copper layer having a thickness of 8 μm or less, and having a total thickness of 2 to 20 μm.

Examples of the active metal forming the active metal layers in these two layers include Ti, Zr, Hf, V, Nb, and Ta. In addition, in both the thin layer A and the thin layer B, the order of the silver layer and the active metal layer (in the case of the thin layer A), the silver layer, the active metal layer and the copper layer (in the case of the thin layer B) is exceptional. Although not limited thereto, in the case of the thin layer A, it is preferable to interpose the active metal layer and the silver layer in this order from the ceramic member side, and in the case of the thin layer B, each layer needs to be only one layer. Not,
A plurality of layers may intervene. Moreover, each layer may be a layer of an alloy of each of these components.

In the thin layer A and the thin layer B, when the thickness of the silver layer is less than 1 μm and the thickness of the active metal layer is less than 0.5 μm, the melt of copper and the active metal decreases, so that the ceramic member, the stress buffering member and the metal member are If the space between the stress buffer and the layer cannot be satisfied, and if the thickness of these layers is thicker than 19 μm, the melt will be too much, the melt will squeeze out from the joint, and the squeezing melt will solidify and cool. In the above, there is a problem that cracks are generated in the ceramic member due to thermal stress based on the difference in thermal expansion coefficient between the ceramic member and the brazing material.
Further, in the thin layer B, even if the thickness of the copper layer is thicker than 8 μm, the amount of melt is large, which causes a situation in which a crack occurs in the ceramic member as described above, which is inconvenient.

The total thickness of both thin layer A and thin layer B is 2 to 20 μm.
Is set to. When this whole layer is thinner than 2 μm, high bonding strength between the ceramic member and the metal member cannot be obtained, and when it exceeds 20 μm, the components of the thin layer A and the thin layer B melted to the outer member of the bonding member at the time of heating and melting. Overhanging and spreading,
Cracks begin to occur in the ceramic member due to thermal stress. It is preferably 2 to 10 μm.

As a method of interposing the thin layer A and the thin layer B, the foil of each layer described above may be placed on the surface of the ceramic member, the metal member, or the stress relaxation member, but the components of each layer described above may be sputtered or evaporated. The method of depositing by a plating method or the like is industrially easy and suitable. If this treatment is applied to the joint surface of the metal member during the deposition of these components, the process is easy and stable joining is possible.

The ceramic member, the thin layer A or the thin layer B, the stress relaxation member, the thin layer A or the thin layer B, and the metal member thus obtained are stacked and heated in a vacuum atmosphere or an inert atmosphere. In this step, basically it is not necessary to apply pressure, but if necessary, low pressure of 1 kg / mm ² or less may be applied for heating. The heating temperature needs to be lower than the melting point of the metal member. Specifically, heating may be performed within the range of 779 ° C. to the melting point of the metal member.

Examples of the Invention Examples 1 to 5 A silicon nitride cylinder having a diameter of 13 mm and a height of 10 mm was used as a ceramic member, and a cylinder of structural carbon steel (S45C defined in JIS G4051) having a diameter of 15 mm and a height of 15 mm was used as a metal member. I prepared. A copper (C1221p specified by JIS H3100) plate having a diameter of 14 mm and a thickness as shown in Table 1 was prepared as a stress buffer member.

A copper plate is interposed between the silicon nitride member and the carbon steel member, and a titanium foil and a silver foil having the thickness shown in Table 1 are sandwiched between the silicon nitride member and the copper plate, and between the copper plate and the carbon steel member to be superposed. 5 × 10 ^-5 Torr, 880 while applying a pressure of 0.1 kg / cm ^2.
It was kept for 30 seconds under the condition of ° C. After cooling in argon gas, the obtained joined body was put into a tensile tester to measure the tensile strength of the joined portion. The above results are collectively shown in Table 1.

In each of Examples 1 to 5, the tensile strength of the joint is 13 kg / mm ² or more, and it is considered that the thermal stress between both members is sufficiently relaxed. On the contrary, in each of the comparative examples, the tensile strength is small, and it is considered that defects such as cracks are generated on the joint surface. In fact, in the case of Comparative Example 2, the silicon nitride member was cracked.

Example 6 A bonded body was manufactured in the same manner as in Example 5 except that a molybdenum columnar body having the same shape was used as the metal member, and the thickness of the silver foil and the thickness of the titanium foil were each 3 μm.

The maximum value of tensile strength of the obtained joined body is 10.9 kg at room temperature.
/ mm ^2, 400 was 8.4 kg / mm ² at 15.7kg / mm ^2, 600 ℃ at ° C..

Example 7 A silicon carbide columnar body having the same shape as the ceramic member, a SUS316 columnar body having the same shape as the metal member, and a stress buffering member having a thickness of 1 mm.
The same method as in Example 1 except that a thin layer B made of a titanium foil having a thickness of 3 μm, a silver foil having a thickness of 5 μm, and a copper foil having a thickness of 2 μm was used in place of the tungsten disc and the thin layer A. A joined body was obtained.

The tensile strength of the joint was 6.6 kg / mm ² at room temperature.

[Effects of the Invention] As is clear from the above description, the method of the present invention can very easily join a ceramic member and a metal member to produce a joined body that suggests various functionalities. Then, the cracking phenomenon of the ceramic member, which frequently occurs in the past, is prevented or suppressed, and the bonding strength at the bonding portion is increased. Moreover, the appearance of the melt is good without any protrusion of the melt at the joint.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromitsu Takeda 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. (56) Reference JP-A-60-177635 (JP, A) Kaisho 60-239373 (JP, A)

Claims (3)

[Claims] 1. A stress buffer member having a thickness of 0.2 mm or more is interposed between a ceramic member and a metal member, and between the ceramic member and the stress buffer member and between the metal member and the stress buffer member. A silver layer having a thickness of 1 to 19 μm and a thickness of 0.5
Consisting of an active metal layer of ~ 9 μm and having a total thickness of 2
Or a thin layer A having a thickness of 1 to 19 μm, an active metal layer having a thickness of 0.5 to 9 μm and a copper layer having a thickness of 8 μm or less, and having a total thickness of 2 to 20 μm. A method for joining a ceramic member and a metal member, which comprises heating B after interposing B. 2. The method according to claim 1, wherein the stress buffering member comprises copper or a copper alloy. 3. The method according to claim 1, wherein the active metal is titanium or zirconium.