JPH04365362A - Ceramic-metal based junction - Google Patents

Abstract

PURPOSE:To dissolve such-problems that cracks are caused in connections and ceramics by a heat stress caused by a temperature change and also provide a ceramic-metal based junction presenting excellent radiation or the like. CONSTITUTION:A metal material 1 (presenting superplasticity) indicating a huge expansion under an operating stress in a specific temperature area, or a metal radical composite material 1 scattering and including ceramic particulates with the metal material (metal) as a radical is connected to a ceramic substrate 2 at a plurality of locations. With the later cooling process, the embodiment is abruptly cooled up to a specific temperature presenting superplasticity to cause a stress on purpose, alternatively it is pressed in the specific temperature area presenting the superplasticity, so that a plastic deformation is caused in the metal material 1 or the metal radical composite material 1 and a ceramic-metal based junction is obtained by mitigating the stress to be caused at cooling.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic-metal bonded body, and more particularly to a ceramic-metal bonded body which has excellent heat dissipation properties and thermal fatigue resistance and is suitable for substrates for semiconductor devices.

0002

2. Description of the Related Art For example, in mounted circuit devices (hybrid modules), there is a demand for high-density packaging, hybridization, or intelligence of power semiconductor elements. In response to such requests,
The problem is how to efficiently dissipate the large amount of heat generated by driving the mounted semiconductor element to prevent or reduce the temperature rise of the semiconductor element. For this reason, a heat dissipating substrate configured by integrally disposing a Cu layer or an Al layer with good thermal conductivity on the surface of a ceramic substrate such as Al2O3 is used for mounting the power semiconductor elements. , or A that has both thermal conductivity and insulation properties
Ceramic substrates such as IN and SiC are used. These heat dissipating boards have a wiring pattern made of conductive metal on the main surface that electrically connects to the power semiconductor elements to be mounted or mounted, or a ground layer made of conductive metal. It is placed as an inner layer.

0003

[Problems to be Solved by the Invention] However, when a heat dissipating substrate or a heat dissipating ceramic substrate constructed as described above is used for mounting the power semiconductor element, etc., the following problems occur. That is, the coefficient of thermal expansion of the ceramic and the conductive metal is, for example, Cu:1.
7×10-6/°C, ALN: 4×10-6/
℃, large thermal stress is generated in the joint due to temperature changes at the joint, and cracks are likely to occur in the joint or the ceramic substrate. In other words, problems such as damage to the configured power semiconductor module. There is.

[0004] As a means to alleviate the thermal stress caused by the integration of the ceramic and conductive metal, it is known to use Mo or W, which has a coefficient of thermal expansion close to that of ceramics, as the conductive metal. Since the electrical resistance of W is three times higher than that of Cu, it is not suitable for cases where good conductivity is required.

[0005] In consideration of these problems, a method has also been developed to combine a Cu layer exhibiting good conductivity with a base material containing particles and pores that are effective in relieving thermal stress (
(Japanese Patent Application Laid-Open No. 63-179734). Although this method is effective in alleviating thermal stress, the presence of the particles and pores not only causes an increase in electrical resistivity or a decrease in bonding strength and an increase in electrical resistivity, but also sometimes causes problems in the bonding process. There is a problem in that the brazing material enters the pores and reduces or loses the thermal stress relaxation effect.

The present invention has been made to solve the above problems, and solves the problem of cracks occurring in joints or ceramics due to thermal stress caused by temperature changes.
The object of the present invention is to provide a ceramic-metal bonded body exhibiting good heat dissipation properties.

[0007]

[Means for Solving the Problems] The ceramic-metal bonded body according to the present invention is a metal material that exhibits superplasticity under applied stress at a predetermined temperature, or a metal based on this metal and containing ceramic fine particles dispersed therein. A bonded body of a matrix composite material and a ceramic substrate, wherein thermal stress is relaxed between the metal material or the metal matrix composite material and the ceramic substrate by utilizing the superplasticity of the metal in the metal material or metal matrix composite material. It is characterized by being integrated.

That is, the ceramic-metal bonded body of the present invention is made of a metal material that exhibits enormous elongation (exhibits superplasticity) under applied stress in a specific temperature range, or is made of a metal material (metal) based on this metal material (metal). A metal matrix composite containing dispersed ceramic fine particles is bonded to a ceramic substrate at multiple locations, and during the subsequent cooling process, the temperature is rapidly raised to a specific temperature at which it exhibits superplasticity to intentionally generate stress. The structure is such that the metal material or metal matrix composite material is pressurized in a specific temperature range exhibiting plasticity to cause plastic deformation, thereby relieving the stress generated during cooling. In other words, the main point is to utilize the temperature at which superplasticity is exhibited, which is generally lower than the bonding temperature, or in other words, the superplasticity exhibited during the cooling process.

In the present invention, the metal material (including alloy) or metal matrix composite material that exhibits superplasticity at a predetermined (specific) temperature is gradually treated by increasing the composition ratio of the metal exhibiting superplasticity on the side to be joined. It is also possible to have a structure changed to, and the metal structure preferably has crystal grains as fine as possible. Furthermore, in metal matrix composite materials, if the ultrafine-grained ceramic is dispersed, the metal grain structure will not be damaged by the high temperatures during bonding, and superplastic deformation will occur in the temperature range where superplasticity occurs. When deforming, the temperature at which this superplastic deformation occurs can be lowered, which is advantageous in terms of process.

On the other hand, as the ceramic substrate, a material having good thermal conductivity such as AlN, SiC, BeO, etc., or a laminate of Cu or Al and a ceramic insulator such as Al 2 O 3 can be used.

[0011]

[Function] In the ceramic-metal bonded body according to the present invention, it is possible to bond a ceramic substrate to a metal material or metal matrix composite material that exhibits superplasticity at a predetermined temperature, or a metal material or metal that exhibits superplasticity at a predetermined temperature. When bonding ceramic substrates together via a matrix composite material,
The thermal stress generated at these joints is easily and sufficiently absorbed and alleviated by the superplastic deformation of the metal material or metal matrix composite material exhibiting superplasticity, resulting in cracks in the joints or the ceramic substrate. The fear of doing so is completely eliminated. In other words, the thermal stress that occurs due to the difference in thermal expansion with the ceramic substrate is easily absorbed and relaxed, effectively preventing or avoiding the occurrence of cracks, and even under usage conditions where heating and cooling are repeated, no damage occurs. It always performs the required function as a thermally conductive substrate.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows C as a metal material 1 exhibiting superplasticity at a predetermined temperature.
This is a cross-sectional view of the structure of a joined body of a u-Zn alloy plate and an Al2O3 plate serving as a ceramic substrate 2. The ceramic-metal bonded body is constructed as follows. That is,
Ti-Ag- as a brazing material was applied to the surfaces to be joined of the Cu-Zn alloy plate 1 and the Al2O3 plate.
Cu is deposited by vapor phase growth. Next, Cu
- The surfaces to be joined of the Zn-based alloy plate 1 and the Al2O3 plate 2 are brought into contact with each other, overlapped, and brazed at 780°C, then cooled to 550°C and bonded to Cu-Zn at this temperature.
The alloy plate 1 is plastically deformed at a strain rate of 10-2 S-1 and then cooled to room temperature.

Example 2 FIG. 2 shows a metal material 1 exhibiting superplasticity at a predetermined temperature.
This is a cross-sectional view of the structure of a joined body of a Cu plate containing a Cu-Zn alloy dispersed therein and an AlN plate serving as a ceramic substrate 2.

The ceramic-metal bonded body is constructed as follows. That is, C
Cu plate 1 in which u-Zn alloy is dispersed and contained in high concentration on the joint surface side (composition changes in stages) and
T as a brazing material is applied to each surface of the AlN plate 2 to be joined.
i-Ag-Cu is deposited by vapor phase growth. Next, Cu-Zn alloy plate 1 and Al2O3
The surfaces of the plates to be joined are stacked against each other and brazed at 780°C, then cooled to 550°C and soldered at this temperature.
The Cu plate 1 containing the u-Zn alloy dispersed therein is plastically deformed at a strain rate of 10-2 S-1 and then cooled to room temperature.

Example 3 FIG. 3 shows A as a metal material 1 exhibiting superplasticity at a predetermined temperature.
Fine grain Al2O3 in l-Cu-Mg alloy
2 is a cross-sectional view showing the structure of a joined body of a metal matrix composite material plate containing dispersed/containing aluminum and an AlN plate serving as a ceramic substrate 2.

The ceramic-metal bonded body is constructed as follows. That is, Al
-Metal matrix composite material plate 1 and AlN in which fine grains of Al2O3 are dispersed and contained in a Cu-Mg alloy
Ti as a brazing material is applied to each surface of the plate 2 to be joined.
- Deposit Ag-Si by vapor phase growth. Next, the surfaces of the metal matrix composite material plate 1 and the Al2O3 plate to be joined are brought into contact with each other and overlapped, and after being brazed at 560°C, it is cooled to 430°C and Al-Cu-
A metal matrix composite material plate 1 in which fine grains of Al2O3 are dispersed and contained in a Mg-based alloy is plastically deformed at a strain rate of 1 S-1 and then cooled to room temperature.

Example 4 FIG. 4 shows C as a metal material 1 exhibiting superplasticity at a predetermined temperature.
This is a cross-sectional view of the structure of a joined body of a metal matrix composite material plate in which fine grains of TiO2 are dispersed and contained in u and an AlN plate serving as a ceramic substrate 2.

The ceramic-metal bonded body is constructed as follows. That is, Cu
The surfaces of the metal matrix composite material plate 1 and the AlN plate 2, in which fine grains of TiO2 are dispersed and contained, are placed one on top of the other, facing each other, and bonded at 1065°C.
Cool to 70 °C, and at this temperature fine grains of Ti are formed in Cu.
The metal matrix composite material plate 1 in which O2 is dispersed and contained is plastically deformed at a strain rate of 10 S-1 and then cooled to room temperature.

[0020] The ceramic-metal bonded bodies obtained above all exhibited a better bonding state than conventional ceramic-metal bonded bodies, and exhibited a bonding condition near the temperature at which plastic deformation was applied to the metal material exhibiting superplasticity. When a thermal fatigue test was performed 10 times between
No cracks occurred in the ceramic substrate. It should be noted that the ceramic-metal bonded body according to the present invention is not limited to the configuration exemplified above, but may be formed by, for example, a general metal plate 3 and a ceramic substrate as shown in cross section in FIGS. 5 and 6, respectively. A structure may be adopted in which a metal material 1 or a metal matrix composite material plate 1 exhibiting superplasticity at the predetermined temperature is interposed between the two and integrally bonded. And Figure 6
In the configuration, the composition of the metal material 1 exhibiting superplasticity is increased so that the metal composition exhibiting superplasticity on the side of the bonding interface with the ceramic substrate 2 is increased (exhibiting enormous elongation), and the metal plate 3
It is desirable that the bonding interface side with the metal plate 3 has a composition similar to that of the metal plate 3 or a configuration in which the same metal phase is formed.

[0021]

[Effects of the Invention] As explained above, the ceramic-metal bonded body according to the present invention is composed of a ceramic substrate and a metal material or metal matrix composite material exhibiting superplasticity, or a metal material or metal matrix composite material exhibiting superplasticity. It has a structure in which the ceramic base and the metal plate are joined and integrated via the . Therefore, it is possible to actively cause a huge elongation, or in other words, superplasticity, of the metal material or metal matrix composite material exhibiting superplasticity during the bonding, and to utilize this to effectively generate thermal stress associated with bonding. has been relaxed. Therefore, the problem (or fear) of cracks occurring in the joint or the ceramic substrate due to thermal stress caused by temperature changes is completely eliminated or prevented, and the original purpose and function of the ceramic-metal joint is maintained. Sufficient retention and performance over a period of time. In other words, when put to practical use as a heat dissipating board for a mounted circuit device, it contributes to the heat dissipation of the mounted/mounted semiconductor element and performs the specified operation, but it is damaged during the manufacturing process or during the process of driving the mounted circuit device. There is nothing to do.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of a ceramic-metal joined body according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the ceramic-metal joined body according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the ceramic-metal joined body according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the ceramic-metal joined body according to the present invention.

FIG. 5 is a sectional view showing another example of the structure of the ceramic-metal joined body according to the present invention.

FIG. 6 is a cross-sectional view showing still another example of the structure of the ceramic-metal joined body according to the present invention.

[Explanation of symbols]

1...Metal material or metal matrix composite material exhibiting superplasticity
2... Ceramic base 3... Metal plate (normal)

Claims (1)

[Claims] 1. A joined body of a ceramic substrate and a metal material exhibiting superplasticity under applied stress at a predetermined temperature, or a metal matrix composite material based on this metal and containing ceramic fine particles dispersed therein, comprising: 1. A ceramic-metal bonded body, characterized in that a metal material or metal matrix composite material and a ceramic substrate are integrated by relaxing thermal stress by utilizing the superplasticity of the metal in the metal material or metal matrix composite material.