JPH03242385A - Bond structure of substrate of aluminum nitride and metallic plate - Google Patents

Abstract

PURPOSE:To obtain bond structure having high reliability while preventing cracks of AlN substrate during heat treating and cooling in bonding an AlN substrate to a metal plate by brazing, by using titanium plates as intermediate layers of bonding. CONSTITUTION:Titanium plates 3 are brazed through brazing materials 2 of first layers to an AlN substrate 1. Copper plates 5 for heating are brazed through brazing materials 4 of second layers to the titanium plates 3 to bond the AIN substrate to the metal plates.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses aluminum nitride (AQN), which has good heat dissipation properties.
It relates to a structure in which a substrate and a metal plate are joined.

Specifically, the present invention relates to the structure of a bonded body of an AQN substrate and a metal plate, which is used as a substrate material for mounting, for example, an IC package, a power diode, or the like.

[Background Art] In order to cope with the increase in heat generation due to higher density, higher speed, and higher output of semiconductor devices, substrate materials with excellent heat dissipation are required. AQ, which has been commonly used as a substrate material with good heat dissipation,
Instead of 203, AQN is attracting attention. However, in applications where higher heat dissipation is required as a mounting board, it is necessary to bond a metal plate with a thickness of several hundreds of nanometers to the AQN board as a heat sink in order to improve the heat dissipation.

For this reason, in the past, as shown in FIG.
and a copper (Cu) plate 22 are bonded together and used as a substrate material. That is, there is a C between the AQN board 21 and the copper plate 22.
After sandwiching the u-Ag-Ti based brazing material 23, heat treatment is performed in a vacuum to fuse the brazing material 23 and join the AQN substrate 21 and the copper plate 22. This copper plate 22 serves as a heat sink to improve the heat dissipation of the fabric substrate 21, and is also used as a wiring pattern if necessary.

[Problem to be solved by the invention] However, as mentioned above, A
In the method of bonding a DH board and a copper plate, since there is a large difference in the coefficient of thermal expansion between the AQN board and the copper plate, as the thickness of the copper plate to be bonded increases, a large amount of residual heat is generated between the AQN board and the copper plate during heat treatment and cooling. Stress was generated, cracks were generated in the AQN substrate, and the reliability of the product was lowered due to the influence of residual thermal stress.

The present invention was made in view of the drawbacks of the conventional examples described above, and its purpose is to prevent the occurrence of cracks in AQN substrates during heat treatment and cooling, and to create a highly reliable bonded structure. It is about providing.

[Means for Solving the Problems] Therefore, in the bonding structure of an aluminum nitride substrate and a metal plate of the present invention, a titanium plate is brazed onto the aluminum nitride substrate via a first layer of brazing material, and this titanium It is characterized by a metal plate for heat dissipation being brazed onto the plate via a second layer of brazing material.

Note that the brazing material is preferably a brazing material containing silver and copper.

[Function] In the present invention, a titanium plate with a relatively low Young's modulus and high ductility is used as the intermediate layer for bonding the AQN substrate and the metal plate. The plate undergoes plastic deformation. As a result, the titanium plate absorbs thermal stress and reduces the residual thermal stress between the AQN substrate and the metal plate, so that cracks and the like do not occur in the At2N substrate, making it possible to obtain a highly reliable substrate material.

[Example] Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a schematic diagram of a bonded body A manufactured by the bonding method of the present invention, in which a titanium plate 3 is brazed onto an AQN substrate through a layer of brazing material 2. A copper plate 5 is brazed thereon with a layer of brazing material 4 interposed therebetween.

An example of a method for manufacturing this joined body A will be described in accordance with the manufacturing order. First, AQ with a thickness of 635 mm and dimensions of 2 inches square.
An N substrate 1 was prepared, and a layer of Cu-Ag-Ti based brazing material 2 was formed to a thickness of 5 cm on this AQN substrate 1 by screen printing. Further, a titanium plate 3 having a thickness of 100 uyl was placed thereon, and a layer of brazing material 4 was formed on the titanium plate 3 in the same manner as the layer of brazing material 2. Then, on top of that, add a thickness of 3
Copper plate 5 of 00 lessons was stacked. With the AQN substrate 1, titanium plate 3, and copper plate 5 stacked together with the brazing materials 2 and 4 interposed in between, the
Heat treatment was performed at °C for 1 minute. As a result, the AQN substrate 1 and the titanium plate 3 were brazed together, and the titanium plate 3 and the copper plate 5 were also brazed by heat treatment, so that a joined body as shown in FIG. 1 was obtained.

The bonded body manufactured by the above method has a good heat dissipation property.
Since a copper plate with good heat dissipation properties is bonded to the QN board, the copper plate functions as a heat sink, resulting in even better heat dissipation properties. Therefore, it can be used as a substrate material with excellent heat dissipation properties, and can be used as a package for semiconductor devices such as ICs and power diodes to suppress temperature increases in semiconductor devices. Moreover, since the heat treatment is performed in a vacuum, there is no generation of thermal conduction inhibiting substances such as oxides, and there is no reduction in heat dissipation from the metal plate.

Furthermore, since a titanium plate with a low Young's modulus and high ductility is sandwiched between the AQN substrate and the copper plate, the plastic deformation of the titanium plate can alleviate thermal stress during cooling, and the AQN
Cracks do not occur in the substrate, and a bonded body with extremely high reliability can be obtained compared to the case where only a brazing material layer with low ductility is provided as in the conventional example.

(Test Results) A joined body according to an example of the present invention was manufactured according to the manufacturing method and numerical example of the above example. As a result, a bonded body with strong bonding strength was obtained, and no cracks occurred in the AQN substrate.

On the other hand, as a comparative example, instead of a titanium plate, C of the same thickness was used.
A u-Ag-Ti based brazing plate was sandwiched between an AQN substrate and a copper plate, and heat treatment was performed under the same conditions as in the example. As a result,
In the comparative example, cracks occurred in the AQN substrate after cooling after brazing.

[Effects of the Invention] According to the present invention, the intermediate titanium plate allows the brazing material to absorb thermal stress during cooling, thereby reducing residual thermal stress between the AQN substrate and the metal plate and preventing cracks in the AQN substrate. can be prevented and a highly reliable substrate material can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional example. 1... Aluminum nitride (AQN) substrate 2.4...
Brazing material 3...Titanium plate 5...Copper plate

Claims (1)

[Claims] (1) A titanium plate was brazed onto the aluminum nitride substrate through a first layer of brazing material, and a metal plate for heat dissipation was brazed onto this titanium plate through a second layer of brazing material. A bonding structure between an aluminum nitride substrate and a metal plate.