JPH0634431B2 - Ceramics circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a ceramic circuit board obtained by directly bonding a copper plate to a ceramic substrate.

(Prior Art) In recent years, as a circuit board such as a board for a power transformer module or a board for a switching power supply module, a board in which a metal plate such as a copper plate is bonded to a ceramic substrate is often used.

As a method of manufacturing such a ceramics circuit board, a punched copper circuit board having a predetermined shape is placed in contact with a ceramics board made of, for example, an aluminum oxide sintered body or an aluminum nitride sintered body, and heated to form a bonding interface. Cu- Cu
_A so-called DBC in which a eutectic liquid phase of ₂ O is generated, the surface of a ceramic substrate is wetted by this liquid phase, and then cooled and solidified to directly bond the ceramic substrate and the copper circuit board.
The method (direct bondig copper method) is becoming popular.

The ceramic circuit board formed by the DBC method has a strong bonding strength between the ceramic board and the copper circuit board,
Since it has a simple structure, it can be miniaturized and highly packaged, and it has the advantage that the work process can be shortened.

(Problems to be Solved by the Invention) By the way, since the ceramics substrate used for such a ceramics circuit board is usually rectangular and each corner is used as it is, the ceramics substrate is not used during the heat treatment or the module. There has been a problem that the occurrence rate of defects is high, such as a catch on a carrying rail or the like in a carrying line during the automatic assembly such as mounting and chipping. Further, in some cases, there is a problem that the transportation line is stopped due to this.

The present invention has been made to solve such conventional problems, and an object of the present invention is to provide a ceramics circuit board that can be smoothly transported in each step and has a low failure rate.

[Structure of the Invention] (Means for Solving Problems) A ceramic circuit board of the present invention is a ceramic circuit board in which a copper plate having a predetermined shape is arranged on a ceramic substrate and heat-bonded to each other. The corners are chamfered, and the corners of the copper plate corresponding to the corners of the ceramic substrate are also chamfered.

The ceramics substrate used in the present invention includes an oxide-based ceramics sintered body such as alumina and beryllia or a non-oxidized ceramics sintered body such as aluminum nitride, silicon nitride, titanium nitride and silicon oxide. Is mentioned. When a non-oxide type ceramic substrate is used, it is preferable to oxidize the bonding surfaces before use.

Then, these ceramic substrates are used by chamfering each corner in advance. This chamfering may be C surface processing or R processing, and the size of this C surface processing or R processing is 0.1 ~
A range of 1.0 mm is preferred. If the size of the C surface processing or R processing is less than 0.1 mm, the effect of preventing crossing cannot be sufficiently obtained,
Even if it exceeds 1.0 mm, it is not possible to obtain any further effect, and if chamfering is applied to each corner of the ceramic substrate, the distance from the corner of the ceramic substrate to the copper plate to be bonded becomes short and the withstand voltage becomes insufficient. Therefore, it is necessary to reduce the size of the copper plate used, which is not preferable because the component mounting area is reduced.

In the present invention, each corner of the copper plate corresponding to each corner of the ceramic substrate is chamfered in order to maintain the required withstand voltage without reducing the size of the copper plate used. The chamfered shape of the corner of the copper plate is preferably the same as the ceramic substrate.

The copper plate used in the present invention is preferably a copper plate obtained by rolling copper containing oxygen in a proportion of 100 to 3000 ppm, such as tough pitch copper.

The ceramics circuit board of the present invention can be obtained by placing a copper plate in contact with a ceramics substrate whose corners have been chamfered in advance and heating it. The heating temperature is below the melting point of copper (1083 ° C) and above the eutectic temperature of copper and oxygen (1065 ° C). When using a copper plate containing oxygen, it is preferable to heat it in an inert gas atmosphere, and when using a copper plate that does not contain oxygen, heat it in an atmosphere containing oxygen of 80 to 3900 ppm. Is preferred.

(Operation) In the ceramics circuit board of the present invention, since the ceramics board in which each corner is chamfered in advance is used,
Transport in the heat treatment process and component mounting process can be performed smoothly, and the occurrence of defects due to breakage of corners is significantly reduced.

(Example) Next, the Example of this invention is described.

Example As shown in FIG. 1, each corner 1a of a ceramic substrate 1 containing alumina of 50 mm × 25 mm × 0.635 mm as a main component (96% and containing a sintering additive of 4% in addition), 0.5C for 1a ...
Used for the C surface processing, on which the corners 2a corresponding to the corners 1a, 1a ...
A copper plate 2 of a predetermined shape, which has been similarly subjected to C-face machining of 0.3C, is placed in contact with 2a ... and at a temperature of 1070 ° C. in a nitrogen gas atmosphere.
It was heated and bonded for 10 minutes.

In the ceramic circuit board thus obtained, the occurrence rate of transport trouble in the automatic process was 0.01% or less. Moreover, the withstand voltage was also sufficiently satisfied.

On the other hand, for comparison with the present invention, in the case of the ceramic circuit board manufactured in the same manner except that the chamfering at each corner of the ceramic board in the example was not performed, the occurrence rate of the transport trouble was 0.1%.

Example 2 As shown in FIG. 2, instead of performing C-face processing on each corner 1a, 1a ... Of the ceramic substrate 1 in Example 1,
A 0.5R rounded R is used, and a 0.3R rounded is also applied to each corner 2a, 2a ... Corresponding to each corner 1a, 1a ... Of the ceramic substrate 1 of the copper plate 2. A ceramic circuit board was produced under the same conditions as in Example 1 except that

Also in such a ceramic circuit board, Example 1
The same effect as was obtained.

[Effects of the Invention] As described above, the ceramic circuit board of the present invention is
Since the ceramic substrate with chamfered edges is used in advance, troubles during transportation are reduced, and the incidence of defects such as chipping is greatly reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing a ceramics circuit board according to an embodiment of the present invention, and FIG. 2 is a plan view showing a ceramics circuit board according to another embodiment of the present invention. 1 ... ceramic substrate 1a ... corner 2 ... copper plate 2a ... corner

Claims (3)

[Claims] 1. A ceramic circuit board comprising a ceramic board on which a copper plate having a predetermined shape is arranged and heat-bonded, and each corner portion of the ceramic substrate is chamfered and corresponds to each corner portion of the ceramic substrate. Ceramic circuit board characterized in that each corner of the copper plate is also chamfered. 2. The ceramic circuit board according to claim 1, wherein each corner of the copper plate corresponding to each corner of the ceramic substrate is chamfered in the same shape as each corner of the ceramic substrate. 3. The ceramic circuit board according to claim 1 or 2, wherein the chamfer has a size in the range of 0.1 to 1.0 mm.