JPS61281078A - Method of joining ceramics to metal, same ceramics each other or different ceramics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining ceramics and metals, or between ceramics of the same type or ceramics of different types.

[Conventional technology]

In general, ceramics are more wear resistant than metals.

Although it is a material with excellent properties such as heat resistance, corrosion resistance, and insulation, it has drawbacks such as being fragile to mechanical shock, having poor conductivity, and poor workability.

On the other hand, metals often have advantages over the disadvantages of ceramics.

Therefore, when ceramics is used as a bonded body with metal, it becomes possible to mutually compensate for the drawbacks of each, and the usefulness of ceramics and metal can be utilized together, and ceramic-metal bonding becomes possible. It has a wide range of uses as a body.

In addition, when ceramics of the same type are bonded together, the method of molding the ceramics can be simplified, the size can be made smaller, the price can be lowered, and the range of applications of the ceramics can be extremely widened.

Furthermore, when bonding different types of ceramics, the properties of each ceramic, such as electrical insulation, thermal conductivity, and abrasion resistance, can be mutually complemented.
The range of applications for ceramics is extremely wide.

However, such joined bodies of ceramics and metals are often used under harsh conditions, and in particular, the joints between ceramics and metals are subject to high thermal stress due to the difference in coefficient of thermal expansion between the two. There is a problem that this is likely to occur. Furthermore, in bonding similar ceramics together, there is a problem in that heat-resistant or airtight bonding is required because it is necessary to take advantage of the characteristics of the ceramics. Furthermore, there are similar technical problems in joining different types of ceramics.

For this reason, strong bonding is required between ceramics and metals, between ceramics of the same type, or between ceramics of different types, but the method of achieving such a bond by a single heating using a metal brazing material is extremely useful. It has a high value.

Conventionally, as a method for obtaining a bonded body of ceramics and metal, a method is known in which oxide type ceramics and copper are heated in an oxidizing atmosphere to bond them together (Japanese Patent Publication No. 58
-3999, Japanese Patent Application Laid-Open No. 59-217684)
. Although this method is an excellent method for obtaining good bonding strength with one heating, heating in an oxidizing atmosphere forms a copper oxide film on the copper surface that significantly impairs the surface quality, and because of heating at high temperatures, The copper itself deforms,
Therefore, there were drawbacks such as the need for post-processing.

In addition, as a metallization method for sintered ceramics, a manganese-containing metal layer is formed on the surface of sintered ceramics that contains a silicon compound that can cause a reaction between manganese and silicon at a temperature lower than the melting point of manganese. A method of heating to a temperature lower than the melting point of manganese to perform a bonding reaction between manganese and silicon, the method comprising: bringing the manganese-containing metal layer into close contact with the ceramic surface prior to the bonding reaction; A method has been proposed in which manganese is reacted with manganese at a temperature lower than the melting point of manganese (Japanese Unexamined Patent Publication No. 58-204885).

However, this method requires that the manganese-containing metal layer and the ceramic be brought into close contact with each other during heating, and the ceramic to be bonded must contain silicon compounds, that is, SiO2 and SiN4, which can react with the manganese-containing metal layer. However, there was a drawback that the types of ceramics to be joined were limited.

In addition, especially as a metallization method for oxide type ceramics,
For example, 5in2゜Ca mainly using Mo-Mn powder.
A commonly used method is to apply a metallized paste containing O or the like, sinter it in a heat-reducing atmosphere to form a metallized layer, and then plate it with Ni and braze it. This method requires two heating steps, one for sintering and one for brazing, and Ni plating must be performed in between, resulting in poor productivity and the need for complicated process control.

Furthermore, an active metal method is known in which a metal active against oxygen, such as Ti, Zr, or Nb, is bonded by utilizing a reaction at the interface between the ceramic and the ceramic. For example, a Ti-25%v-25%Cr alloy is used for alumina, and the bonding temperature is 1,550 to 1.650°C in an inert atmosphere such as vacuum or Ar. This method required a high bonding temperature and was limited by equipment, resulting in low productivity.

Furthermore, in oxide type ceramics, nitride type ceramics, and carbide type ceramics, at least one of sodium fluoride and calcium fluoride, or a mixture of these and kaolin has been used as an active ingredient as an adhesive for bonding ceramics together. An adhesive has been proposed (Japanese Unexamined Patent Publication No. 58-95668). However, although this method has a high bonding strength after bonding, it has the disadvantage that the bonded surfaces become semi-molten during bonding heating, making it difficult to maintain mutual dimensional accuracy of the ceramics after bonding.

[Problem that the invention seeks to solve]

As described above, various methods have been proposed to date for joining ceramics and metals or ceramics together, but each method has its own problems. A part of this problem has already been described, but if this point is also considered and organized further, it will be as follows.

First of all, in addition to the above-mentioned problems, the conventional copper oxide method described above suffers from the difference in thermal expansion coefficient between the ceramic and the copper layer when subsequently bonding to a metal structure using the metallized surface obtained by this method. Due to this, cracks occur on the ceramic side when hard brazing is performed at around 800°C, so the
It must be joined to a metal structure by soft brazing, which is performed at temperatures below 00°C. As a result, the final joint strength was weak overall, and due to the low heat resistance of ceramics and soft brazing, there was a serious problem that the performance could not be fully developed. .

In addition, the conventional bonding method using manganese-containing metals requires heating and pressurization at the same time, which poses the problem of requiring complicated jigs or equipment. It is necessary to contain it in the side, which may deteriorate the characteristics of the ceramic, and at the same time there is a problem that the types of ceramics can be limited.

In addition, the conventional Mo-Mn method described above requires a complicated process of sintering and Metsky brazing, and at the same time, Mn is mixed into brittle glass materials with relatively low melting points such as Sing and CaO.
There is a problem in that a heterogeneous layer consisting of a mixture of powders such as O, W, etc. remains.

In addition, in the conventional active metal method described above, the melting point of the brazing filler metal used for joining is high, and there are significant restrictions from the equipment perspective, resulting in low productivity and high temperatures. Due to this difference, the overall bonding strength had to be low.

Furthermore, the conventional ceramic adhesive using at least one of sodium fluoride and calcium fluoride, or a mixture of these and kaolin, diffuses vigorously into the bonded ceramics, and a semi-molten glass layer is formed at the ceramic bonding interface. There are problems in that it is difficult to maintain dimensional accuracy between the ceramics and at the same time it is difficult to obtain a uniform boundary layer over the entire joint surface.

Therefore, the present invention solves all of the problems of the conventional methods described above, makes it easy to control the temperature during heating bonding, stably obtains high bonding strength with - times of heating, and The object of the present invention is to provide an industrially useful method for joining ceramics and metals, ceramics of the same type, or ceramics of different types, in which mutual dimensional accuracy can be easily maintained.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventor discovered that titanium and a metal brazing material with a lower melting point than titanium that can form an alloy with titanium are used in the joints between ceramics and metals. If a bonding method is adopted in which a part of the titanium is diffused into the metal brazing material by interposing them so that they are in contact with each other and heating them in a vacuum to a temperature where the brazing material melts but the titanium remains solid, It has been learned that all of the above problems can be solved, and that a bonded body with particularly high bonding strength between ceramic and metal can be obtained.

In general, titanium exhibits good wettability to ceramics in its molten state and has the property of diffusing into ceramics, so various metal brazing materials have been developed that take advantage of this property.

However, when using a titanium-copper binary alloy, for example, in a brazing filler metal containing a large amount of titanium,
Its melting point is 890° C. for 20% by weight titanium and 970° C. for 33% by weight titanium. Further, when a titanium-nickel binary alloy is used, the melting point is the lowest at 27% by weight of nickel, and its melting point is 960°C. Since the brazing temperature is set approximately 50°C to 150°C higher than the melting point of the brazing material, the actual joining temperature is 940°C to 1,000°C.
The temperature had to be as high as 120°C.

As a result, bonding workability deteriorated, and even a slight difference in coefficient of thermal expansion between the objects to be bonded due to high-temperature heating generated large internal stress, resulting in poor bonding properties. Further, these brazing materials containing a large amount of titanium are generally brittle and have low ductility after brazing.

On the other hand, silver brazing filler metal, copper brazing filler metal containing a small amount of titanium,
Nickel brazing filler metals are also considered, and although these can provide ductile properties with a relatively low melting point, they have poor wettability to ceramics and still do not provide sufficient bonding properties.

In contrast, in the present invention, as described above, titanium and a metal brazing material having a lower melting point than titanium that can form an alloy with the titanium are placed separately at the joint parts of the objects to be joined, so that the two are not alloyed. For example, one or both of them may be in the form of a plate, and the two may be placed in contact with each other, and heated to a temperature such that the low-melting point brazing metal melts but the titanium remains solid. This is what I did.

In this case, in the early stage of heating, the molten low-melting-point metal brazing filler fluid-tightly fills the space between the ceramics to be joined and the solid titanium, and has good wettability with respect to the amount of titanium. Contact. Here, since titanium and the metal brazing material have the property of being able to alloy with each other, a phenomenon occurs in which titanium partially dissolves and diffuses into the metal brazing material due to subsequent heating and insulating, and this diffusion causes the brazing material itself to become ceramic. It comes to exhibit sufficient wettability against.

The diffused titanium is further diffused into the ceramic (thereby greatly contributing to an increase in the bonding strength of the ceramic).

On the other hand, the amount of titanium in the brazing metal decreases due to the diffusion into the ceramics, but this is successively replenished from solid titanium that contacts the brazing metal with good wettability. The amount of titanium is kept constant, and this amount can be set to the necessary minimum by controlling the heating temperature and heating time.

For this reason, there is no problem of excessive titanium existing in the brazing filler metal after heat treatment; the metal brazing filler metal itself remains ductile, and since it itself has a relatively low coefficient of thermal expansion and is heated at a low temperature, no residual titanium remains. There is little effect on deterioration of bonding properties due to stress. Furthermore, solid titanium decreases as it dissolves and diffuses into the brazing metal during heat treatment, so by appropriately determining its initial amount and heat treatment temperature of 9 hours, titanium becomes a component of the brazing metal after heat treatment. It is also possible to achieve a state in which almost no residue remains. but,
Even if this remains, it does not particularly adversely affect the bonding properties of ceramics, and there is no need to intentionally avoid this remaining.

In addition, in this invention, by performing the above-mentioned thermal bonding in a vacuum, it is possible to improve the wettability of the metal brazing material to titanium at the initial stage of heating, and also to improve the wettability of the metal brazing material to titanium by dissolving and diffusing titanium into the brazing material. This makes it possible to improve the wettability of the material itself to ceramics.

As described above, according to the bonding method of the present invention, titanium's good wettability and diffusivity to ceramics can be fully utilized, and the heating temperature during bonding can be set low, so that ceramics and metals can be bonded together. It is possible to significantly improve the bonding strength with the material, and also to improve the bonding workability.

This invention was made based on the above knowledge,
The gist of this is that in the method of joining ceramics and metals, ceramics of the same type, or ceramics of different types, titanium and a metal brazing material with a lower melting point than titanium that can form an alloy with titanium are interposed in each joint. Ceramics and metals, characterized in that a part of titanium is diffused into the metal brazing material by heating in vacuum at a temperature higher than the melting point of the metal brazing material and at a temperature at which titanium remains in a solid state. It is a method of joining ceramics of the same type or ceramics of different types.

[Structure and operation of the invention]

The joining method of the present invention includes a joining method between ceramics and metals, between ceramics of the same type, and between ceramics of different types. The above-mentioned ceramics include all conventionally known ceramics such as oxide-type ceramics and nitride-type ceramics, and there are no particular restrictions on the metal to be bonded to it as long as it has a melting point higher than that of the brazing material. Examples include metals or alloys such as Ti, Cu, Fe, and Ni, and alloys of these metals and other metals.

Bonding of similar ceramics refers to, for example, bonding of oxide-type ceramics or bonding of nitride-type ceramics, and bonding of different types of ceramics refers to, for example, bonding of oxide-type ceramics and nitride-type ceramics. etc.

In the present invention, the metal brazing material used for the above-mentioned bonding may be one that can be alloyed with titanium and has a melting point lower than that of titanium, and generally exhibits good wettability with titanium when heated in a vacuum. Specifically, limited aluminum (Ag72%).

Cu28%), lithium-containing silver solder (Ag72%).

Cu27゜8%, LiO, 2%), palladium wax (P
d5%, Ag6.8%, Cu27%), palladium solder (Pd10%, Ag58%, Cu27%), copper solder (
Cu100%), copper alloy solder (Cu68%, Mn22
%, NiO%), gold solder (Au38%, Cu62%
) can be selected and used as appropriate from conventionally known metal brazing materials. Note that all percentages in parentheses above are percentages by weight.

In addition, if at least one of manganese and molybdenum, preferably both, is included as a component of the metal brazing material, this will promote the dissociation reaction on the ceramic surface during heating and melting, thereby improving the bonding. Gives good results to characteristics. Therefore, the use of such waxy phase components is particularly preferred in the present invention.

In this invention, first, the metal solder as described above is brought into close proximity to the material, titanium, and the door, and is interposed at each joint between ceramic and metal, between ceramics of the same type, or between ceramics of different types. This intervening means is arbitrary and may be appropriately determined depending on the type of brazing metal used and the combination with titanium.

The intervening form can take various forms such as a plate, a single powder, a coating, or a combination of these. It may be in a standalone state without being converted into

That is, in the case of a plate, it is extremely convenient to use if it is made into a clad plate with a required amount of soldered metal foil affixed to both sides of titanium foil. In addition, in the case of linear or powdered titanium, for example, if the required amount of silver or copper is plated on the surface of the titanium, the required amount of silver or copper corresponding to the ratio of the ingredients (mentioned above) can be laminated so as to become the required components after melting. When heated, they are alloyed and can similarly exhibit the effects of the present invention as a metal wax phase component.

In addition, when used as a cladding plate between titanium and a metal brazing material, a lithium-containing silver solder with better wettability to the ceramic (
(mentioned above), and a palladium brazing filler metal (which has good bonding properties) is placed on the joint surface of the metal made of Ni, Fe, or their alloy.
By pasting the above-mentioned brazing materials, a strong bonded body of the ceramic and the metal can be obtained in -times of heating operation, since these two metal brazing materials have substantially similar melting points.

Furthermore, when using at least a part of the metal brazing material, such as molybdenum or manganese as mentioned above, the above-mentioned joint is coated with a paste made of screen oil or the like and applied in the form of a coating on the joint of the ceramic. It may be made to intervene.

The amount of metal brazing material used in these various embodiments is, for example, when titanium is plate-shaped and normal butt brazing is performed, the surface area of one side of the titanium joint is 1
20 to 100 μ per crA is appropriate. Of course, the amount used is determined by the joining shape and the desired solidified shape or required characteristics of the brazing filler metal after joining, and can be freely selected.

Further, the amount of titanium is not particularly limited, and the amount and shape of titanium may be arbitrarily selected so that it is present over the entire area of the joint and there is no problem in use even if a portion of it remains after heating and cooling. .

In addition, in this invention, as mentioned above, by heating in vacuum, a part of the titanium coexisting with the metal brazing material in the joint part diffuses into the brazing material (thereby ensuring wettability to ceramics, Since the bonding mechanism is based on the subsequent diffusion of titanium into the ceramic, there is no need to perform any particularly troublesome pretreatment on the ceramic bonding area during the above-mentioned intervention, just purify it by cleaning. That's fine.

After being interposed in this manner, it is subjected to heat treatment in a vacuum. The heating temperature at this time must be above the melting point of the metal brazing material and at a temperature at which the titanium remains in a solid state, that is, the temperature must be such that the metal brazing material and titanium do not melt as a whole and form an alloy. Generally, the temperature is 50°C to 1° below the melting point of the metal brazing material, that is, the liquidus temperature.
It is sufficient to maintain the temperature at a temperature 50°C higher.

The holding time can be selected depending on the amount of titanium to be dissolved and diffused into the molten brazing metal, that is, the amount of titanium diffused and dissolved, which is determined depending on each joining mode, and this amount of dissolution is a function of temperature and time. However, 2 to 30 minutes is usually sufficient. One hour at such a temperature is not much different from normal brazing work conditions for metals together, and greatly contributes to improving productivity.

The degree of vacuum during this heat treatment is set to 1.5 degrees in order to prevent high-temperature oxidation of titanium and improve wettability of the metal brazing material.
It is preferable to set the degree of vacuum to a high degree of vacuum of 10-'m5) (g or higher, more preferably 10-'wHg or higher).

Through the above heat treatment, the metal brazing material first melts and adheres to the titanium surface with good wettability in the initial stage of heating, and then the titanium gradually dissolves and diffuses into this molten brazing material, so that the brazing material itself is well bonded to the ceramics. Wet,
Titanium that has diffused into the brazing filler metal further diffuses into the ceramic. The titanium consumed by this diffusion is replenished as appropriate, further than the titanium in contact with the molten brazing material, until an equilibrium amount is reached.

Since the above-mentioned equilibrium amount can be adjusted to the necessary minimum by setting the heating temperature, etc., the metal brazing material after heat treatment maintains good ductility, and this and the above-mentioned molten brazing material have good wettability to ceramics. Due to the diffusion effect of titanium into the ceramic, a bonded body with good bonding properties, that is, a very high bonding strength between ceramic and metal, etc., can be obtained.

Next, in the above-mentioned joining method, the inventor added in advance at least one kind or two or more kinds selected from nitrides, carbides, or borides of titanium or zirconium together with the brazing metal and titanium to the joining portion. By intervening (in particular, it is possible to further improve the wettability of the metal brazing filler metal to ceramics, it is also possible to achieve high strength at the same time as ductility after solidification of the filler metal, and furthermore, both of these compounds have high Because of its melting point, it was found that the metal brazing filler metal exhibits a shape-retaining function when heated and melted.

The physical properties of these compounds and their main properties are shown in Table 1 below, and as can be seen from this table,
All of these compounds have a small coefficient of thermal expansion, and by selecting one or more of them in combination, it is possible to bring the coefficient of thermal expansion of the brazing filler metal closer to that of the ceramics to be joined. It is also effective in relieving stress.

Among the above compounds, Tic is a good electrical conductor, so when making a ceramic printed circuit board using ceramics, titanium powder, and metal brazing powder, for example, if Tic is mixed with the above powder, the metal brazing material itself can be used. Since TiC has good wettability with TiC, the shape retention function resulting from the high melting point of TiC prevents the brazing filler metal from flowing excessively toward the ceramic, making it easier to manufacture printed circuit boards.

These compounds are generally used in the form of powder of about 150 mesh baths, and the amount used is about 100 mesh baths of metal brazing material.
! The amount is preferably about 1 to 20 parts by weight, more preferably about 3 to 7 parts by weight, based on the lit part. In addition, as a method for intervening these compounds in the joint, it is possible to mix them in powder form in the metal brazing material component, or to mix them with an organic binder such as screen oil and apply the mixture to the ceramic joint and dry it. You can also take

〔Effect of the invention〕

As described above, in the present invention, titanium and a metal brazing material that has a low melting point that wets the titanium and can be alloyed with titanium are interposed in the joint, and a temperature at which the brazing material becomes a melt in a vacuum is provided. A portion of the titanium is diffused into the brazing filler metal by heating to a temperature of By adopting this method, all the problems with the conventional bonding methods mentioned above are solved, and in particular, it is possible to obtain stable and high bonding strength by one heating regardless of the type and shape of ceramics or metals, and
When joining, the dimensional accuracy of the joined parts can be ensured well,
Further, it is possible to provide an industrially advantageous joining method that allows easy temperature control during heating joining and enables mass production.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In the following, % and parts mean % by weight and parts by weight, respectively. In addition, the solder solders used in each example and the lithium solders used have the metal compositions described above. In other words, silver solder is 72% Ag.

Cu is 28%, and the lithium-containing silver solder is Ag72%, C
U27.8%, Li 0.2%.

Example 1 A ceramic cylinder with an alumina content of 80% was placed on a ceramic disc with an alumina content of 80%, and a
A 1.5 cm square titanium foil with a thickness of 0 μm was placed, and a 100 μm thick solder or lithium-containing silver solder was placed in sufficient contact with both sides of the titanium foil. This silver solder or lithium-containing silver solder has a surface area of 1 on one side of titanium.
It is 38.9■ per cIa.

Separately, a silicon nitride ceramic with a thickness of 3 m and a size of 10 cm square was placed on a ceramic disk with an alumina content of 80%, and a titanium foil of 1 cm square with a thickness of 100 μm was placed on the joint, and further as described above. A filler metal solder or a lithium-containing silver solder having the same proportions as the titanium foil was placed in sufficient contact with both sides of the titanium foil.

Charge the above two combinations into a vacuum furnace, and
After performing a heat treatment at 880° C. for 7 minutes at a vacuum level of IO-’11 Hg, it was cooled in a furnace and taken out to obtain four types of joined bodies. A portion of titanium remained at the joint of each bonded body. The bonding characteristics of each bonded body were as shown in Table 2 below.

Table 2 Example 2 A ceramic cylinder with an alumina content of 80% is placed on a ceramic disc with an alumina content of 80%, and a
A 1.5 cm square titanium foil with a thickness of 0 μm was placed, and silver solder with a thickness of 100 μm was placed in sufficient contact with both sides of the titanium foil. This silver solder has a surface area of 38.9 square meters per 1 d of surface area of one side of titanium. In addition, for the above-mentioned joint part, a titanium or zirconium nitride, carbide, or boride (all 250 mesh bath) kneaded with screen oil was added to the above-mentioned joint, so that the above-mentioned compound was mixed in accordance with Table 3 per 100 parts of the metal brazing material. The number of coats shown was applied and thoroughly dried.

Separately, a silicon nitride ceramic with a thickness of 3 m and a size of 10 fl square was placed on a ceramic disk with an alumina content of 80%, and a titanium foil and a lithium-containing silver solder were attached to the joint using the same operation and ratio as above. Further, TiBz as a titanium compound was applied and dried in the same manner as above.

Charge the above two combinations into a vacuum furnace, and
I
Zero zygotes were obtained. A portion of titanium remained at the joint of each bonded body. The bonding characteristics of each bonded body are shown in the third section below.
It was as shown in the table.

Table 3 Example 3 A ceramic cylinder with an alumina content of 80% is placed on a ceramic disc with an alumina content of 80%, and a
A 1°5 cm square titanium foil with a thickness of 0 μm was placed, and an additional 1.00 mm thick was placed. crm thick solder or lithium-containing silver solder was placed in full contact with both sides of the titanium foil. In this example, the amount of the above-mentioned silver solder or lithium-containing solder was 23.4 cm per 1 d of surface area of one side of titanium.
1.1■, 38.9■.

7788■ and its bonding characteristics were examined.

Charge the above combination into a vacuum furnace and
After performing a heat treatment at 880° C. for 7 minutes in a vacuum of nHg, it was cooled in a furnace and taken out.

A zygote with a large ridge was obtained. A portion of titanium remained at the joint of each bonded body. The bonding characteristics of each bonded body are shown in the fourth section below.
It was as shown in the table.

Table 4 (Note 1)...Indicates the weight of the metal brazing filler metal per 1c11N of surface area on one side of titanium (Note 2)...There is no breakage from the brazing filler metal (in any case, there is no breakage due to damage to the ceramics or more). As is clear from the results of the Examples, it can be seen that according to the method of the present invention, a bonded body with high bonding strength can be manufactured with good workability.

Claims (2)

[Claims] (1) A method for joining ceramics and metals, ceramics of the same type or ceramics of different types, in which titanium and a metal brazing material having a lower melting point than titanium that can form an alloy with titanium is interposed in each joint,
Ceramics, metals, and similar ceramics characterized in that a part of titanium is diffused into the metal brazing material by heating in vacuum to a temperature higher than the melting point of the metal brazing material and at a temperature at which titanium remains in a solid state. A method of joining similar or dissimilar ceramics. (2) A patent claim characterized in that at least one or two or more selected from nitride, carbide, or boride of titanium or zirconium is interposed in each joint together with titanium and a metal brazing material. A method for joining ceramics and metals, the same type of ceramics, or different types of ceramics as described in scope item (1).