JPH1112051A - Joining material - Google Patents

Abstract

(57) [Problem] It is impossible to directly and firmly join a ceramic body and a metal member made of copper via a joining material. The silver is 45% to 95% by weight, titanium,
1% by weight of at least one of zirconium and hafnium
To 10% by weight, 0.1% to 50% by weight of tin, and the balance of copper, and a joining material for joining a ceramic body and a metal member formed of copper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining material for joining a ceramic body and a metal member formed of copper.

[0002]

2. Description of the Related Art In a device such as an electric vehicle which uses a large amount of power as a driving source, it is necessary to handle a large amount of power in a power module for controlling the driving power. As a circuit board used in such a power module, for example, a metallized metal layer such as tungsten or molybdenum is applied to the surface of an insulating base made of ceramics such as an aluminum oxide sintered body, The layer has a structure in which a circuit conductor made of a copper plate is joined via a brazing material such as silver brazing.

[0003] In the circuit board used for the power module, the metallized metal layer applied to the insulating base made of ceramics acts as a base metal for brazing a circuit conductor made of a copper plate to the insulating base. A paste obtained by adding a suitable organic binder and a solvent to a high melting point metal powder such as tungsten or molybdenum on the surface of a raw ceramic body serving as an insulating substrate or a ceramic body obtained by firing the raw ceramic body to form a paste. Is applied by screen printing, and then fired in a reducing atmosphere, and the refractory metal powder and the ceramic body are sintered and integrated to form a predetermined pattern on the surface of the insulating base made of ceramics. You.

However, like the circuit board used in the conventional power module, the joining of the ceramic body and the metal member made of copper requires a metallized metal layer to be applied to the surface of the ceramic body in advance. In order to apply a metallized metal layer to the surface of the ceramic body, it is necessary to prepare a metal paste in advance. Since it is manufactured by pulverizing so as to obtain a paste by adding an organic binder and a solvent and forming a paste, there is a disadvantage in that a great amount of time and labor is required for manufacturing a metal paste.

The metallized metal layer using tungsten, molybdenum, or the like is only applied to an oxide-based ceramic body represented by an aluminum oxide-based sintered body, and is formed from an aluminum nitride-based sintered body or a silicon carbide-based sintered body. However, since it does not adhere to a nitride-based ceramic body and a carbide-based ceramic body represented by the above, there is also a disadvantage that the material on the ceramic body side is greatly restricted in joining the ceramic body and the metal member.

In order to solve the above-mentioned disadvantages, at least one of titanium, niobium and zirconium is used as a bonding material which can directly bond a metal member made of copper to a ceramic body. A bonding material comprising 35 to 90% by weight of copper and the balance being silver has been proposed (see Japanese Patent Application Laid-Open No. 5-246770).

To join a ceramic member and a metal member made of copper using such a joining material, a joining material is placed between the ceramic member and the metal member made of copper, and then the member is placed in a vacuum at 850 ° C. To a temperature of, diffuse the active metal of at least one of titanium, niobium and zirconium into the ceramic body, and join the eutectic of silver and copper to the metal member made of copper to form The metal member is directly joined.

[0008]

However, when a ceramic member and a metal member made of copper are joined by using this joining material, a part of copper forming the metal member is dissolved in the joining material and joined. The melting point of the material rises, particularly the melting point of the region that comes into contact with the metal member greatly increases locally. As a result, the wettability of the bonding material with respect to the metal member greatly decreases, and voids (holes) are formed in the bonding material. A drawback was induced that a large amount was formed and the bonding strength was greatly deteriorated.

The present invention has been made in view of the above-mentioned drawbacks, and has as its object to improve the wettability of a bonding material to a metal member made of copper and to directly and firmly bond a ceramic body and a metal member. It is to provide a bonding material that can be used.

[0010]

The bonding material for bonding the ceramic body of the present invention to a metal member made of copper is as follows.
45% to 95% by weight of silver, 1% to 10% by weight of at least one of titanium, zirconium and hafnium, 0.1% to 50% by weight of tin, and the balance of copper. Things.

According to the bonding material of the present invention, at least one of titanium, zirconium and hafnium diffuses into the ceramic body, and the bonding between the bonding material and the ceramic body becomes strong.
In addition, silver and copper are improved in wettability by tin and excellently bonded to the metal member, whereby the ceramic body and the metal member made of copper are directly and strongly bonded via the bonding material.

According to the bonding material of the present invention, the ceramic body and the bonding material are bonded by diffusing at least one of titanium, zirconium, and hafnium in the bonding material into the ceramic body. Strongly bonded not only to oxide ceramics represented by aluminum oxide sintered bodies, but also to nitride ceramics and carbide ceramics represented by aluminum nitride sintered bodies and silicon carbide sintered bodies As a result, the material on the ceramic body side in joining the ceramic body and the metal member is not greatly restricted.

In the joining material of the present invention, when the amount of silver is less than 45% by weight, the amount of intermetallic compound of copper and tin increases when joining the ceramic body and the metal member, and the joining material is reduced. As a brittle material, the reliability of the mechanical strength of the joint is greatly reduced, and if it exceeds 95% by weight, the wettability between the joint material and the metal member made of copper is reduced, and voids are formed in the joint material. As a result, the bonding strength is greatly deteriorated. Therefore, the amount of silver in the joining material is specified in the range of 45% to 95% by weight.

If the amount of titanium, zirconium, hafnium, etc. is less than 1% by weight, the bonding strength between the ceramic body and the bonding material is weak, and if it exceeds 10% by weight, the bonding material becomes brittle and the bonding machine becomes weak. The reliability of the target strength is greatly reduced. Therefore, the amount of at least one of titanium, zirconium, and hafnium in the bonding material is specified in the range of 1% by weight to 10% by weight.

If the amount of tin is less than 0.1% by weight, it is not possible to effectively prevent the copper of the metal member from dissolving in the joining material and increasing the melting point of the joining material. In addition, voids are formed in the joining material, and the joining strength is greatly deteriorated. When the content exceeds 50% by weight, the amount of intermetallic compound of copper and tin increases, and the joining material is considered to be brittle. The reliability of the target strength is greatly reduced. Therefore, the amount of tin in the joining material is specified in the range of 0.1% by weight to 50% by weight.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be sharpened based on embodiments. First, powders of silver (Ag), titanium (Ti), zirconium (Zr), hafnium (Hf), tin (Sn) and copper (Cu) are weighed to the composition shown in Table 1, and then the organic vehicle is added thereto. To prepare a bonding material sample as a paste.

Next, the above-mentioned joining material sample was subjected to an aluminum oxide sintered body (Al ₂ O ₃ ) and an aluminum nitride sintered body (A
1N) and a silicon carbide sintered body (SiC) having a length of 2
5 mm, width 25 mm, thickness 0.635 mm on the surface of a flat ceramic body, length 20 mm, width 2 mm, thickness 50
μm, and 20 mm long and 2 m wide on the top surface
Then, a copper plate having a thickness of 0.3 mm and a thickness of 0.3 mm is placed thereon, and then heat-treated in a vacuum (10 ⁻⁵ Torr) at a temperature of 850 ° C. for 20 minutes. Join.

Then, the end of the copper plate finally joined in the longitudinal direction is pulled in a direction perpendicular to the ceramic body, and a tensile force when the copper plate is peeled off from the ceramic body is obtained. The strength was examined.

At the same time, the joining material after joining the ceramic body and the copper plate is observed with an ultrasonic microscope, the area of voids formed in the joining material is examined, and the rate of occurrence of voids formed in the joining material is examined. I asked.

Sample Nos. 25 to 28 are comparative samples for comparison with the present invention. Sample Nos. 26 to 28 cover a ceramic body with a metallized metal layer made of tungsten whose surface is previously coated with a nickel plating layer. A copper plate is bonded to the metallized metal layer via a silver brazing material.

The comparative sample 25 is disclosed in JP-A-5-2467.
This is a joining material described in Japanese Patent Publication No. 70-70.

The above results are shown in Table 1.

[0023]

[Table 1]

[0024]

As can be seen from the above embodiment, when a ceramic member and a metal member made of copper are joined using a conventional joining material, a part of the copper forming the metal member is contained in the joining material. The melting point of the joining material is increased by melting, and the wettability of the joining material to the metal member is greatly reduced due to the melting. At the same time, a large amount of voids (holes) are formed in the joining material and the joining strength is 7.6 kgf /. cm or less, whereas the bonding material of the present invention effectively prevents the melting point of the bonding material from rising, improves the wettability between the bonding material and the metal member, and attaches the metal member to the ceramic body. Bonding can be performed with a bonding strength of 4 kgf / cm or more.

In the bonding material of the present invention, the ceramic body and the bonding material are bonded by diffusing at least one of titanium, zirconium and hafnium in the bonding material into the ceramic body. Firmly bonded not only to oxide-based ceramics represented by porous sintered bodies but also to nitride-based ceramics and carbide-based ceramics represented by aluminum nitride-based sintered bodies and silicon carbide-based sintered bodies, As a result, there is no great restriction on the material on the ceramic body side in joining the ceramic body and the metal member.

Claims (1)

[Claims] 1. A method according to claim 1, wherein the silver comprises 45 to 95% by weight, titanium,
1% by weight of at least one of zirconium and hafnium
To 10% by weight, 0.1% to 50% by weight of tin, and the balance of copper, and a joining material for joining a ceramic body and a metal member formed of copper.