JPH03259589A - Ceramic circuit board and its manufacture - Google Patents

Abstract

PURPOSE:To prevent a burr from being produced at an end part of a metallized layer and to enhance an electrical characteristic by a method wherein several metallized layers whose size corresponds to a circuit board are formed on a nitride AL substrate, substrateexposed parts are formed between the layers and the substrate is cut along the parts. CONSTITUTION:Several metallized layers 12 whose size corresponds to a circuit board are formed on the surface 11a of a Al nitride substrate 11. The layers 12 are divided at exposed parts, i.e., at non-metallized parts 13, on the surface of the substrate 11. When the metallized layers 12 are formed by printing a paste for metallization use, the parts 13 are formed and end parts of the layers 12 are formed to be R-shaped. The substrate 11 is cut along the parts 13 by using a cutter 14; a circuit board 15 of a required size is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a ceramic circuit board having a metallized layer obtained through cutting and a method for manufacturing the same.

(Prior art) Ceramic substrates made of alumina or aluminum nitride have traditionally been used as circuit boards for various electronic devices. For the purpose of improving solder wettability, a metal layer is formed on the surface using various methods. As a method for forming a metal layer, for example, a method is known in which a metallization paste containing Mo or W as a main component is applied and fired at a predetermined temperature to form a metallization layer.

On the other hand, ceramic substrates containing aluminum nitride as a main component have superior thermal conductivity compared to alumina substrates, so they are attracting attention as mounting substrates for high-output and highly integrated semiconductor devices, such as heat sinks. When an aluminum nitride substrate is used as a heat sink for a semiconductor device as described above, it is possible to reduce the size of the substrate due to its excellent heat dissipation properties.

When forming a metallized layer as described above on such a miniaturized aluminum nitride substrate (for example, 5sm x 5mm), the metallized layer is formed on both sides of the aluminum nitride substrate having the size of a predetermined circuit board, such as a heat sink. Since it is extremely inefficient to do so, it is usually formed by the method shown below.

That is, as shown in FIG. 4, first, a metallized layer 2 is formed all over the surface 1a of an aluminum nitride original substrate 1 having a size that allows production of a plurality of required circuit boards. Thereafter, the aluminum nitride original substrate 1 having the metallized layer 2 is cut using a diamond cutter 3 or the like so as to correspond to the size of each circuit board. A circuit board 5 having individual metallized layers 2 formed on its surface is obtained.

(Problem to be Solved by the Invention) However, as described above, in the method of cutting the aluminum nitride original substrate 1 including the metallized layer 2 to produce the ceramic circuit board 5 of the desired shape, the method shown in FIG. As shown, there was a problem in that there was a high possibility that burrs 6 and the like would be formed at the ends of the metallized layer 2 of the obtained circuit board 5.

The fringes 6 generated by the above-mentioned cutting can cause leaks and reduce electrical characteristics, such as a decrease in withstand voltage.The fringes 6 can also reduce dimensional accuracy, which can lead to defects. It has become.

The present invention was made in order to address the problems of the prior art, and it prevents the occurrence of burrs at the edges of the metallized layer of a ceramic circuit board obtained through cutting, and improves electrical characteristics and dimensional accuracy. The purpose of the present invention is to provide a ceramic circuit board with excellent performance and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) In other words, the ceramic circuit board of the present invention includes an aluminum nitride substrate having at least l cut surfaces as end faces, and at least one main surface of the aluminum nitride substrate. and a metallized layer provided on the metallized layer, and an end portion of the metallized layer has an R shape.

Furthermore, the method for manufacturing a ceramic circuit board of the present invention provides a plurality of metallized layers corresponding to the required size of the circuit board on an aluminum nitride substrate, and an exposed portion of the aluminum nitride substrate that separates these metallized layers individually. and a step of cutting the aluminum nitride substrate along the exposed portion of the aluminum nitride substrate while corresponding to the shape of the circuit board.

(Function) In the present invention, first, a plurality of metallized layers corresponding to the required size of the circuit board are formed on an aluminum nitride substrate. Further, an exposed portion of the aluminum nitride substrate is provided between these metallized layers as a cutting margin. Then, by cutting the aluminum nitride substrate along the exposed portion of the aluminum nitride substrate, a ceramic circuit board having the required size and with individual metallized layers formed thereon can be obtained without directly cutting the metallized layer. It will be done. In this way, since the metallized layer is not directly cut, generation of flash at the ends of the metallized layer is prevented. Also,
The ceramic circuit board obtained by cutting in this way is pre-formed with a metallized layer corresponding to the individual size, so the edge of the metallized layer is given an R shape, which improves electrical resistance such as withstand voltage. Characteristics improve.

(Example) Next, examples of the present invention will be described.

FIG. 1 and FIG. 2 are diagrams each schematically showing the manufacturing process of a ceramic circuit board according to an embodiment of the present invention. The method for manufacturing the ceramic circuit board of this example will be described below with reference to these figures.

First, a ceramic substrate 11 is prepared, which has a size that allows a plurality of desired circuit boards to be mounted thereon, and whose main component is aluminum nitride, which is the base material for the circuit boards.

Next, a plurality of metallized layers 12 are formed on the main surface 11a of the aluminum nitride original substrate 11 in a size corresponding to the size of the metallized portion to be formed on each circuit board. These metallized layers 12 are separated and divided into individual sizes by exposed portions of the surface of the aluminum nitride original substrate 11, that is, non-metalized portions 13 (FIG. 1-A and FIG. 2-A).

The non-metalized portion 13 serves as a cutting margin during cutting, and is set to have a width greater than the thickness of the blade of the cutter used during cutting.

The metallized layer 12, which is individually divided by such non-metalized portions 13, is formed, for example, as follows.

M o on the aluminum nitride original substrate 11 .

A metallizing paste containing a WsrV group a active metal as a main component is printed in a pattern shape in which each metallized layer 12 is divided by non-metalized portions 13 using a screen printing technique. Thereafter, it is fired at a temperature depending on the metallizing paste used to obtain individually separated and divided metallized layers 12.

Here, since each metallized layer 12 is formed separately during printing, the end portion of each metallized layer 12 is given an R shape.

After forming the metallized layer 12 in this manner, the aluminum nitride original substrate 11 is set in a precision cutting machine (not shown) or the like, and a diamond cutter 14 with a peripheral blade, for example, having a blade thickness narrower than the width of the non-metalized portion 13 is used. Accordingly, the circuit board is cut into the desired size along the cutting marks made of the non-metalized portion 13 (in the direction of arrow a in the figure). By this cutting, the metallized layers 12 are individually formed, and the ceramic circuit board 15 having the required size is formed.
(Fig. 1-B and Fig. 2-B).

The ceramic circuit board 15 obtained in this way is
As shown in FIG. 3, on the main surface of the aluminum nitride substrate 16 having the desired size of the circuit board, an R
A metallized layer 12 having a shape is formed, and the occurrence of flakes and the like is prevented.

According to the above-described method for manufacturing a ceramic circuit board, metallization of 2.0 am x 5.2 av is separated and divided by a non-metalized portion 13 of 0.21 mm in width on an aluminum nitride original substrate 11 of 50.8 sm x 50.8 s+n. A ceramic circuit board 1 is formed by forming a plurality of layers 12 and cutting the aluminum nitride original substrate 11 into individual sizes using a diamond cutter 14 with a blade thickness of 0.2 mm.
When No. 5 was produced, good results were obtained, with no occurrence of flakes and dimensional variations within ±30 μm.

As in this embodiment, the metallized layers 12 are formed in advance on the aluminum nitride original substrate 11 to have individual sizes, and the metallized layers 12 are separated by non-metalized parts 13, and the metallized layers 12 are separated along the non-metalized parts 13. By cutting the ceramic circuit board 15 to the size of each individual ceramic circuit board 15, a desired ceramic circuit board can be obtained without directly cutting the metallized layer. Therefore, it is possible to prevent the end portion 12a of the metallized layer 12 from forming, thereby improving electrical characteristics and dimensional accuracy.

In addition, as mentioned above, since the metallized layer 12 of each ceramic circuit board 15 is formed to suit the individual size, the end portion thereof is given a rounded shape, and furthermore, the electrical characteristics such as withstand voltage etc. improves.

Furthermore, the rounded end portion 12a also has the effect of preventing chips, cracks, etc. caused by handling.

In the above embodiment, the ceramic circuit board 15 has been described in which the metallized layer 12 is formed only on one main surface of the aluminum nitride substrate 16, but the same effect can be obtained even when the metallized layer is formed on both surfaces. .

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent the occurrence of burrs at the edges of the metallized layer of a ceramic circuit board formed through cutting, and furthermore, the edges are provided with a rounded shape. As a result, a ceramic circuit board with excellent electrical properties such as withstand voltage and dimensional accuracy can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing the manufacturing process of a ceramic circuit board according to an embodiment of the present invention, FIG. 2 is a cross-sectional view thereof, and FIG. 3 is a cross-sectional view showing a ceramic circuit board according to an embodiment of the present invention. 4 is a sectional view schematically showing the manufacturing process of a conventional ceramic circuit board, and FIG. 5 is a sectional view showing a conventional ceramic circuit board obtained through the manufacturing process shown in FIG. 4. 11... Aluminum nitride original substrate, 12...
...Metallized layer, 12a...R-shaped end portion, 13...Non-metalized portion, 14...
...Diamond cutter, 15... Ceramic circuit board, 16... Aluminum nitride substrate.

Claims (2)

[Claims] (1) An aluminum nitride substrate having at least one cut surface as an end surface, and a metallized layer provided on at least one main surface of the aluminum nitride substrate, the end of the metallized layer having an R-shape. A ceramic circuit board characterized by having. (2) a step of forming a plurality of metallized layers corresponding to the required size of the circuit board on an aluminum nitride substrate while providing an exposed portion of the aluminum nitride substrate to separate these metallized layers; and the aluminum nitride substrate. a step of cutting the aluminum nitride substrate along the exposed portion thereof in a manner corresponding to the shape of the circuit board.