JPH05319945A - Brazing material for producing ceramic substrate joined to metallic plate - Google Patents

Abstract

PURPOSE:To uniformly disperse a joined part and an unjoined part in the joining face of a ceramic substrate and a metallic plate and prevent concentration of stress and improve thermal shock resistance by uniformly including an oxide in a prescribed amount in a brazing material. CONSTITUTION:The brazing material is formed of powder having 0.1-10mum average particle diameter and has 0.01-2mum thickness and contains 0.01-50wt.% oxide. This brazing material can be formed of mixed powder of oxide particles having 0.1-8mum average particle diameter and a brazing material powder having 0.1-10mum average particle diameter. Further, this brazing material can be formed of silver of a main component and 0.1-10wt.% active metal selected from among titanium, niobium and zirconia. A joined part and unjoined part are uniformly dispersed in a joining face of the ceramic substrate and the metallic plate and concentration of stress is prevented by the brazing material uniformly containing this oxide to provide a ceramic substrate joined to a metallic plate, excellent in thermal shock resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing material for producing a metal plate bonded ceramic substrate.

[0002]

2. Description of the Related Art Conventionally, various methods have been known as methods for metallurgically joining a metal plate to the surface of a ceramic substrate. For example, 1. A mixture of a powder containing molybdenum and tungsten as main components and an organic binder is applied to the surface of the ceramic substrate, and the mixture is heated to 1400 to 1700 ° C. in a humidified atmosphere to react with each other to form a metal layer. A method of applying Ni plating to the surface of the metal layer, and then joining a metal plate (for example, a copper plate) to the Ni plating with Pb-Sn solder or the like. 2. A method of joining a metal plate and a ceramic substrate using a noble metal such as Au or Pt, that is, an alloy whose main component is a metal having a small affinity for oxygen. 3. At the joint between the metal plate and the ceramic substrate, Ti, Nb,
A method is known in which an active metal such as Zr or an active metal hydride that is converted into an active metal by heat treatment is interposed and then bonded at high temperature and high pressure.

However, the above-mentioned method 1 is often used in the case of joining a copper plate as a conductor to the surface of a ceramic substrate as an insulator in an electronic component, but has a drawback that it involves many steps and is complicated. Although the above method 2 can be joined in a simple process, it is not economical because it uses an expensive noble metal, and requires high pressure so that the metal base material and the ceramic base material come into sufficient contact with each other. However, it is not preferable for joining electronic parts and the like that are not susceptible to deformation. Further, the above method 3 has a drawback that it is not preferable for bonding electronic parts which are not susceptible to deformation, like the above method 2, although strong bonding can be achieved by the active metal, but high bonding pressure is required. Was there.

For this reason, for example, an alloy of an active metal such as Ti or Zr and a transition metal such as Cu, Ni or Fe is used, and the melting point (Ti; 1720) of the active metal alone is used in the eutectic composition region. ℃, Zr; 1860 ℃) and melting point of the transition metal simple substance (Cu; 1083 ℃, Ni; 1453 ℃,
Fe; 1534 ° C.), the melting point is several hundred ° C. lower than that of Fe; 1534 ° C.), and an active metal is interposed in the joint between the transition metal base material and the ceramic base material, and the joint portion is an alloy of the transition metal and the active metal. Is higher than the melting point of the transition metal and lower than the melting point of the transition metal, the atoms of the transition metal and the active metal are mutually diffused to form an alloy, and the alloy is used to join the transition metal base material and the ceramic base material. U.S. Pat. No. 2857
No. 663 is disclosed. According to such a method, the joining portion is filled with the melt of the alloy of the transition metal and the active metal at the time of joining and wets the metal base material and the ceramic base material, so that the base materials are sufficiently contacted at the time of joining. Almost no pressurization is required, and the base materials can be strongly bonded by the effect of the active metal.

By the way, metals and ceramics are substances having completely different atomic bonding states. Therefore, when metals and ceramics are joined, their chemical properties such as reactivity, physical properties such as coefficient of thermal expansion, and electrical conductivity are greatly different. Therefore, when a thermal shock is applied to the joining member of the metal and the ceramic, the ceramic itself has a defect that cracks occur, and the metal and the ceramic are metallurgically joined to each other, which is excellent in durability against thermal shock and has high reliability. Obtaining a bonded body was extremely difficult.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks and provides a brazing material for producing a highly reliable metal plate-bonded ceramic substrate having excellent durability against thermal shock. The purpose is.

[0007]

Means and Actions for Solving the Problems
As a result of earnest research to solve the above-mentioned problems, as a result of the brazing filler metal in which the oxide is uniformly present, the ceramic substrate and the metal plate are present in the joint surface with the joint portion and the non-joint portion being almost evenly dispersed. The present invention has been completed based on the new finding that it is possible to manufacture a metal plate bonded ceramic substrate that can be bonded by performing the bonding, prevent concentration of stress in the bonding surface, and have significantly improved thermal shock resistance.

The present invention will be described in detail below. The brazing material of the present invention needs to contain an oxide. The reason is that the brazing material is used for joining the ceramic substrate and the metal plate, and when the brazing material containing an oxide is used for joining, the interface between the joining surfaces at the time of joining the ceramic substrate and the metal plate. Since the oxide is present in the joint, it can be joined in a state where a non-joint portion is created on the joint surface, prevents the concentration of stress in the joint surface, and improves the thermal shock resistance of the metal plate-bonded ceramic substrate. This is because it can be manufactured.

The brazing material of the present invention contains an oxide in an amount of 0.01-5.
It is necessary that the content is 0% by weight. The reason is that if the amount of the oxide is less than 0.01% by weight, it is difficult to make the oxide evenly present on the joint surface between the ceramic substrate and the metal plate, and the amount of non-joint portion formed on the joint surface is insufficient. On the other hand, if it is more than 50% by weight, it is difficult to obtain a strong bond because the non-bonded portion of the bonded surface between the ceramic substrate and the metal plate increases.

The brazing material of the present invention has an average particle size of 0.1 to 1
The powder is preferably 0 μm and has an oxide film with a thickness of 0.01 to 2 μm. The reason why the brazing material is preferably made of powder having an average particle diameter of 0.1 to 10 μm is that the brazing material made of powder having a particle diameter in the above range forms a uniform brazing material layer. This is because it is easy, and the reason why the thickness of the oxide film of the brazing material is preferably 0.01 to 2 μm is
When the thickness of the oxide film is less than 0.01 μm, it is difficult to make the oxide uniformly exist on the joint surface between the ceramic substrate and the metal plate, and the amount of non-joint portion formed on the joint surface becomes insufficient. On the other hand, if it is thicker than 2 μm, the bonding between the ceramic substrate and the metal plate is likely to be incomplete and it becomes difficult to obtain a strong bonding.

The brazing material of the present invention has an average particle size of 0.1-8.
A mixed powder of oxide particles of μm and a brazing filler metal powder having an average particle size of 0.1 to 10 μm is preferable. The reason why the brazing material preferably contains oxide particles having an average particle diameter of 0.1 to 8 μm is that the average particle diameter is 0.1 to 0.1 μm.
This is because the inclusion of 8 μm oxide particles enables the oxide to be uniformly present on the joint surface between the ceramic substrate and the metal plate, and the reason why the brazing material is preferably a powder in the above range The reason is that a uniform brazing material layer can be easily formed.

The brazing material of the present invention has a thickness of 1 to 100 μm.
It is preferable that it is a thin plate containing 0.1 to 100 μm of oxide particles. The reason why the brazing filler metal is preferably a thin plate having a thickness within the above range is that it is difficult to uniformly form a brazing filler metal layer when the thickness is less than 1 μm, whereas when the brazing filler metal layer is thicker than 100 μm, it is strong. This is because it becomes difficult to perform proper joining. Further, the reason why it is preferable to contain the oxide particles within the above range inside is that when the particle size of the oxide particles is smaller than 0.1 μm, the oxide is present evenly dispersed at the interface. On the other hand, if it is thicker than 100 μm, the non-bonded portion of the bonded surface increases, and it becomes difficult to obtain a strong bond.

The brazing material of the present invention preferably contains silver as a main component and 0.1 to 10% by weight of at least one active metal selected from titanium, niobium and zirconia. .. The reason why the brazing material preferably contains at least one active metal selected from titanium, niobium and zirconia is that the active metal easily diffuses into the ceramic substrate and easily diffuses into the ceramic substrate. This is because the ceramic substrate and the brazing filler metal can be bonded to each other extremely strongly. It is considered that the active metal diffuses into the substrate at the contact surface of the ceramic substrate with the brazing material to firmly bond the ceramic substrate and the brazing material. The reason why the content of the active metal is preferably 0.1 to 10% by weight is that the content of the active metal is 0.1% by weight.
If it is less than 10% by weight, it is difficult to sufficiently form a diffusion layer of an active metal on the ceramic and the joint strength tends to be insufficient. This is because not only absorption is insufficient but cracks are likely to occur in the ceramic, but also the diffusion layer in the ceramic becomes unnecessarily thick and the strength of the ceramic itself tends to deteriorate.

An example of a method for producing a metal plate-bonded ceramic substrate using the brazing material of the present invention will be described below. When the brazing material of the present invention is used, for example, a metal plate is placed on a ceramic substrate via the brazing material, fired up to 700 ° C. in an oxidizing atmosphere, and then in a non-oxidizing atmosphere.
The metal plates can be joined by heating to 0 to 950 ° C. for about 10 minutes. By joining under the conditions as described above, the joined portion and the non-joined portion can be present in the joining surface of the ceramic substrate and the metal plate in a substantially evenly dispersed state, preventing the concentration of stress and preventing thermal shock. It is possible to manufacture a metal plate-bonded ceramic substrate having significantly improved properties.

In the metal plate-bonded ceramic substrate of the present invention, the area ratio of the non-bonded portion to the bonded surface is 0.01 to 50.
% Is advantageous. The reason is that if the area ratio is lower than 0.01%, the effect of absorbing stress due to thermal expansion and contraction can hardly be expected, while 50%
This is because if it is higher, sufficient bonding strength cannot be obtained.

The metal plate-bonded ceramic substrate of the present invention has an island-shaped bond of 0.01 to 100 mm ² at the bond.
It is preferable that the particles are scattered or the island-shaped non-bonded portions of 1 to 10 ⁴ μm ² are scattered in an island shape. The reason is that the above-mentioned configuration disperses and miniaturizes the stress generated at the joint, and reduces the stress at the end of the joint surface.Therefore, variations in joint strength are small and stress is not concentrated. This is because it is possible to obtain a difficult joint. The brazing material of the present invention is suitable for oxide substrates such as alumina, mullite and cordierite, and non-oxide substrates such as silicon nitride and aluminum nitride.

It is advantageous to use copper, nickel, iron or an alloy thereof as the metal plate to be joined using the brazing material of the present invention. The reason is that the melting point of the metal plate is higher than the melting point of the brazing filler metal, and moreover, it is easy to form an alloy with the brazing filler metal.

The metal plate-bonded ceramic substrate of the present invention has a ceramic substrate thickness of 0.1 to 5 mm, a metal plate thickness of 0.02 to 1 mm, and a brazing material layer thickness of 0.0.
Advantageously, it is between 03 and 0.03 mm. The reason why the thickness of the ceramic substrate is 0.1 to 5 mm is advantageous because if it is thinner than 0.1 mm, the ceramic substrate is easily broken by thermal stress, and if it is thicker than 5 mm, the thickness of the ceramic substrate is large. This is because it becomes thicker than necessary. Moreover, the reason why the thickness of the metal plate is 0.02 to 1 mm is advantageous because if it is thinner than 0.02 mm, the resistance value as a circuit is high and it is not practical, while if it is thicker than 1 mm, heating is performed. This is because a large amount of stress is generated during cooling and the ceramic substrate is easily broken.

The thickness of the brazing material layer is 0.003 to 0.
The reason why it is advantageous that the thickness is 03 mm is that a preferable bonding strength between the ceramic substrate and the brazing material can be obtained by setting the thickness within this range. Hereinafter, a method of manufacturing a metal plate-bonded ceramic substrate using the brazing material of the present invention will be described in detail based on examples.

[0020]

【Example】

Example 1 70.5 parts by weight of silver having an average particle size of 5 μm,
A brazing filler metal paste containing copper in an amount of 27.5 parts by weight, titanium in an amount of 2 parts by weight, and an oxide film in an amount of 8% by weight on a surface thereof is formed into a plate-like silicon nitride of 45 mm × 45 mm × 0.635 mm. Screen printing was performed on the surface of a substrate made of a sintered body to form a brazing material layer having a film thickness of 25 μm and a shape of 10 mm × 20 mm, leveling was performed at room temperature for 30 minutes, and further drying was performed at a temperature of 60 ° C. for 30 minutes. Then 10 mm
A × 20 mm × 0.3 mm copper plate was placed on the substrate made of a silicon nitride sintered body through the brazing material layer and heat-bonded.
The heat bonding is performed under an oxidizing atmosphere with an oxygen concentration of about 1 ppm.
After heating to 00 ° C and holding for 1 hour, further 3 × 10 ^-5 T
It was carried out by heating to 800 ° C. under a reduced pressure of orr and holding for 10 minutes. It should be noted that the copper plate is bonded to the copper plate at 10
A load of 0 g / cm ² was applied.

The non-bonded portion ratio of the obtained metal plate bonded ceramic substrate was 20%, which was a very good bonded state.

(Example 2) The same as Example 1, except that it was a mixed powder of oxide particles having an average particle size of 5 μm and a brazing filler metal powder having an average particle size of 5 μm. %
Using the brazing material contained therein, a metal plate-bonded ceramic substrate was obtained. The non-bonded portion ratio of the obtained metal plate-bonded ceramic substrate was 25%, which was a very good bonded state.

(Embodiment 3) Similar to Embodiment 1, except that a thin plate having a thickness of 20 μm is used and a brazing material containing 5% by weight of oxide particles having a thickness of 5 μm is used. A ceramic substrate was obtained. The non-bonded portion ratio of the obtained metal plate-bonded ceramic substrate was 25%, which was a very good bonded state.

Using the metal plate-bonded ceramic substrates obtained in Examples 1 to 3, repeated heating and cooling tests were conducted in which the temperature was changed from -65 to 150 ° C in about 30 minutes.
No defects such as peeling of the copper plate or cracks in the substrates were observed in any of the substrates.

[0025]

By using the brazing material of the present invention,
Even if a metal plate and a ceramic substrate having a large coefficient of thermal expansion are bonded, a highly reliable metal plate and a bonded ceramic substrate having excellent thermal shock resistance can be manufactured.

Claims (5)

[Claims] 1. A brazing material for producing a metal plate-bonded ceramic substrate, which comprises 0.01 to 50% by weight of an oxide. 2. The brazing material has an average particle size of 0.1 to 10.
The brazing material for producing a metal plate-bonded ceramic substrate according to claim 1, wherein the brazing material is a powder having a thickness of 0.01 μm and has an oxide film with a thickness of 0.01 to 2 μm. 3. The brazing material has an average particle size of 0.1 to 8 μm.
The brazing material for producing a metal plate-bonded ceramic substrate according to claim 1, which is a mixed powder of oxide particles of m and a brazing material powder having an average particle diameter of 0.1 to 10 µm. 4. The metal plate-bonded ceramic substrate manufacturing method according to claim 1, wherein the brazing filler metal is a thin plate having a thickness of 1 to 100 μm and contains oxide particles having a particle diameter of 0.1 to 100 μm. Brazing material. 5. The metal according to claim 1, wherein the brazing material contains silver as a main component and contains 0.1 to 10% by weight of at least one active metal selected from titanium, niobium and zirconia. A brazing material for manufacturing plate-bonded ceramic substrates.