JP3003179B2 - Joining method of glass ceramic substrate and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method for joining a glass ceramic substrate and a metal, and aims at improving the adhesion between the glass ceramic substrate and the metal. At the time of joining, two layers of brazing material with different melting points are used, and the high melting point brazing material is positioned on the glass ceramic substrate side, and the low melting point brazing material is positioned on the metal side, and then fired under load and integrated. A method for joining a glass ceramic substrate and a metal is configured.

[Industrial applications]

The present invention relates to a method for joining a multilayer circuit board made of glass ceramic and a metal plate.

Optical communication has been widely used due to the need to process a large amount of information quickly.

The feature of the optical communication is that high-speed transmission is possible together with signal multiplexing.

Therefore, semiconductor elements such as LSI and VLSI are configured to be suitable for high-speed signals.

In addition, a circuit board on which this is mounted has low loss and good thermal conductivity, and an electronic circuit needs to be patterned using a metal material having low electric resistance.

[Conventional technology]

The present inventors have proposed a glass ceramic substrate having a new structure in which glass ceramic is used as a substrate material and an electronic circuit is formed using copper (Cu) in order to solve this problem.

In order to put into practical use a multilayer ceramic circuit board having low transmission loss and excellent high-frequency characteristics, the inventors of the present invention have to use resistivity as a constituent material of a conductor pattern. A composite dielectric consisting of borosilicate glass and alumina as a material that satisfies such conditions as being able to use Cu with a low content, having a low dielectric constant, excellent high-frequency characteristics, and excellent heat dissipation of the substrate. I chose the body.

In addition, the structure shown in FIGS. 2A and 2B satisfies such conditions as shortening the wiring distance of wire bonding between the semiconductor element and the multilayer ceramic circuit board to improve the heat dissipation of the semiconductor element. Has been proposed.

That is, an area 2 on which the semiconductor element 1 is mounted is opened to form a glass-ceramic substrate 3, and an aluminum nitride (AlN) substrate 4 having excellent thermal conductivity is placed at the bottom of the opened area 2. After bonding the semiconductor element 1 to the pad, the pad provided on the periphery of the semiconductor element 1 and the pad provided on the glass ceramic substrate 3 are wire-bonded.

The glass ceramic substrate 3 having such a structure needs to be bonded to a metal package in order to obtain a ground potential over the entire area of the substrate.

Conventionally, as shown in FIG. 3, a metallized layer 6 is formed by applying a conductive paste such as a Cu paste to the back surface of the glass ceramic substrate 3 and then sintering it as shown in FIG. 7, a method of bonding to the metal package 5 has been adopted.

However, when the brazing material 7 is melted, the volume expansion occurs due to the insertion of the brazing material 7 into the metallized layer 6, and the contact area of the glass constituting the metallized layer 6 with the substrate is reduced, resulting in a decrease in the adhesive strength. However, there is a problem that the ceramic substrate 3 is easily peeled.

[Problems to be solved by the invention]

The glass-ceramic substrate on which the semiconductor element is mounted must be bonded to a metal package in order to obtain a ground potential over the entire area of the substrate.

In this method, a metal package made of a metal having a thermal expansion coefficient close to that of glass ceramics was used, and bonding was performed using a low melting point brazing material having a melting point of about 600 ° C.

However, when the brazing material is melted during joining, the brazing material penetrates to the joint between the metallized layer and the glass ceramic substrate, causing volume expansion, and as a result, reducing the contact area of the glass serving as a binder, There is a problem that the adhesion strength is reduced to cause peeling.

 Therefore, it is an issue to solve this problem.

[Means for solving the problem]

The above problem is caused by a joining method of joining a metallized glass-ceramic substrate and a metal plate using two layers of brazing materials having different melting points.
A brazing material with a high melting point at 10-50 ° C is positioned on the glass ceramic substrate side, and a brazing material with a low melting point is positioned on the metal side. The problem can be solved by a method of joining a metal and a glass ceramic substrate which is integrated by firing under load at a brazing temperature at which the metal does not melt.

[Action]

In the conventional configuration, peeling is likely to occur because the molten brazing material invades the metallized layer, so the inventors prevent the intrusion and diffuse the components of the brazing material into the metallized layer to make them adhere to each other. I thought it could be solved.

FIG. 1 is a principle view of the present invention, in which two brazing materials having different melting points but similar components are used integrally, and the brazing temperature is set on the side of the metallized layer 6 of the glass ceramic substrate 3 at the brazing temperature. Using a high melting point brazing material 9 that does not melt,
On the side of the metal package 5, a brazing material 10 having a low melting point that is melted at a brazing temperature is used.

At the brazing temperature, the brazing material 10 having a low melting point must be melted, while the brazing material 9 having a high melting point must not be melted. 5050 ° C. has been found to be suitable.

Then, the weight 11 is placed on the metal package 5 and heated at a preset brazing temperature in an inert atmosphere.

In this way, the brazing material 9 having a high melting point diffuses and adheres to the metallized layer, and the metal package 5 adheres to the brazing material 9 having a high melting point via the brazing material 10 having a low melting point. Joining becomes possible.

〔Example〕

The following four types of brazing materials manufactured by Degussa were used to form two layers of brazing materials having different melting points.

Example 1: (When the melting point difference is 30 ° C.) A Cu paste (product number 6001, DuPont) is screen-printed on a glass ceramic substrate having a composition ratio of 50% by weight of borosilicate glass and 50% by weight of alumina, and dried. The metallized layer was formed by firing at 600 ° C. for 10 minutes in an N ₂ atmosphere.

A material A and a brazing material B having a thickness of 0.1 mm are placed on this metallized layer, and gold (Au) plated iron /
A package made of a nickel alloy (Ni: Fe = 4: 58) is placed, and a 100 g weight is placed thereon and heat-treated at 680 ° C. for 5 minutes in an N ₂ atmosphere to separate the glass ceramic substrate and the package. Joined.

The reason why the firing temperature is set to 680 ° C. higher than 640 ° C. is due to the heat capacity of the glass ceramic substrate, and the substrate temperature does not reach 640 ° C. after firing for 5 minutes.

As a result of the measurement, the adhesion strength was 20 MPa, which was a sufficient value as compared with the case where a conventional brazing material was used / the adhesion density was 6 MPa.

Example 2: (Case where melting point difference is 50 ° C) A metallized layer of Cu was formed on a glass ceramic substrate in exactly the same manner as in Example 1.

A 0.1 mm thick brazing material D and a brazing material C are placed on this metallized layer, and gold (Au) plated iron
A package made of a nickel alloy (Ni: Fe = 42: 58) was placed, and a 100 g weight was placed thereon and heat-treated at 790 ° C. for 5 minutes in an N ₂ atmosphere to form a glass ceramic substrate and a package. Was joined.

This adhesion strength was 20 MPa as a result of the measurement, and excellent results were obtained as compared with the case where a conventional brazing material was used and the adhesion density was 6 MPa.

Example 3 (in the case of a melting point difference of 70 ° C.) A metallized layer of Cu was formed on a glass ceramic substrate in exactly the same manner as in Example 1.

A 0.1 mm thick brazing material C and a brazing material A are placed on this metallized layer, and gold (Au) plated iron
A package made of a nickel alloy (Ni: Fe = 42: 58) was placed, and a 100 g weight was placed thereon and heat-treated at 710 ° C. for 5 minutes in an N ₂ atmosphere to form a glass ceramic substrate and a package. Was joined.

As a result of the measurement, the density strength was 15 MPa, and an excellent result could be obtained as compared with the case where the conventional brazing material was used and the adhesion density was 6 MPa.

Comparative Example 1: (Melting point difference: 30 ° C., but arrangement is reversed) A metallized layer of Cu was formed on a glass ceramic substrate in exactly the same manner as in Example 1.

A 0.1 mm thick brazing material B and a brazing material A are placed on this metallized layer, and gold (Au) plated iron
A package made of a nickel alloy (Ni: Fe = 42: 58) was placed, and a 100 g weight was placed thereon and heat-treated at 680 ° C. for 5 minutes in an N ₂ atmosphere to form a glass ceramic substrate and a package. Was joined.

As a result of the measurement, the adhesion strength was 6 MPa, which was the same value as that obtained by using the conventional brazing filler metal and was poor.

Comparative Example 2: (Melting point difference 150 ° C., but arrangement is reversed) A metallized layer of Cu was formed on a glass ceramic substrate in exactly the same manner as in Example 1.

A 0.1 mm thick brazing material B and a brazing material D are placed on this metallized layer, and gold (Au) plated iron
A package made of a nickel alloy (Ni: Fe = 42: 58) is placed, and a 100 g weight is placed thereon and heat-treated at 830 ° C. for 5 minutes in an N ₂ atmosphere to form a glass ceramic substrate and a package. Was joined.

The adhesion strength was 1 MPa as a result of the measurement, which was inferior to that using a conventional brazing filler metal.

〔The invention's effect〕

As described above, according to the embodiment of the present invention, when the glass ceramic substrate is bonded to the metal package, not only does not occur separation, but also a stronger bond can be obtained as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a principle view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a substrate structure (A) proposed by the inventors and a mounting method of a semiconductor element (B), and FIG. 3 is a metal package. FIG. In the figure, 1 is a semiconductor element, 2 is a region, 3 is a glass ceramic substrate, 5 is a metal package, 6 is a metallized layer, 9 is a brazing material having a high melting point, and 10 is a brazing material having a low melting point.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-194879 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 37/00

Claims (1)

(57) [Claims] 1. A joining method for joining a metallized glass ceramic substrate and a metal plate using two layers of brazing materials having different melting points, wherein the difference in melting points between the two layers of brazing materials is 10 to 10 mm.
At 50 ° C, the high melting point brazing material is positioned on the glass ceramic substrate side and the low melting point brazing material is positioned on the metal side, the low melting point brazing material melts, while the high melting point brazing material does not melt A method for bonding a glass ceramic substrate and a metal, wherein the glass ceramic substrate and the metal are integrated by firing under load at a welding temperature.