JPH05308190A - Through-hole metal core board - Google Patents

Abstract

PURPOSE:To provide a through-hole metal core board which enhances an insulating withstand voltage between a wiring pattern including a through-hole metallized part and a metal plate. CONSTITUTION:The title board is constituted in the following manner: a ceramic 2 is formed at the circumference of a metal plate 1; after that, a through hole 3 which is passed from the surface to the rear is formed; a through-hole inner- wall insulator 4 is formed selectively on the inner wall of the through hole 3; and, after that, a through-hole metallization operation is performed by using a conductor 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board on which electronic parts are mounted, and more particularly to a metal-based through-hole metal core board.

[0002]

2. Description of the Related Art Conventional through-hole metal core substrates are
Inorganic powder is dissolved in a solvent in a metal plate with through holes, and the metal plate is immersed in a charged solution in the powder particles, and an insulator is attached around the metal plate by electrophoresis. After that, it is baked at about 900 ° C. for 1 hour to form an insulator with a thickness of 100 to 200 μm. Next, a wiring pattern and a through hole metallization were formed on the insulator by a screen printing method or the like using a thick film conductor such as silver palladium, and then a resistor, a protective glass, etc. were sequentially formed. ..

[0003]

This conventional through-hole metal core substrate is an insulator formed by adhering to the periphery of a metal plate by an electrophoretic method and then firing it. Since the insulating layer is thinned to 1/2 to 1/4, the insulation withstand voltage between the metal plate and the metal plate is insufficient when the through-hole metallization is formed and the wiring patterns on the front surface and the back surface are connected. There was a problem.

[0004]

According to the present invention, there is provided a through-hole metal core including a metal plate, an insulator formed around the metal plate, and a thick film portion covering the insulator. In the substrate, after the surface of the metal plate is provided with an insulator, the metal plate is provided with a plurality of through holes, the inner side wall of the through holes is provided with an insulator, and through hole metallization is performed. A hole metal core substrate is obtained.

Further, in a metal core substrate with a through hole which is composed of a metal plate, an insulator formed around the metal plate, and a thick film portion covering the insulator, an insulator is formed on the surface of the metal plate. Then, a plurality of through holes are provided in the metal plate, and a first insulator is applied to an inner side wall of the through hole by using a screen printing method, and then the first insulator is covered. Further, a through-hole metal core substrate is obtained which is characterized by forming a second insulator and performing through-hole metallization.

[0006]

The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of the first embodiment of the present invention, in which the order of manufacturing steps is (a) to (d).

First, as shown in FIG. 1 (a), a ceramic 2 is attached to the periphery of an iron plate 1 by using an electrophoretic method, and about 90
It is formed by firing at 0 ° C. Iron plate 1
Is about 0.6 mm and the thickness of the ceramic 2 is about 0.1
It is 2 mm. The composition of the ceramic 2 was a crystalline one containing MgO as a main component.

Next, a through hole 3 is formed as shown in FIG. Through holes 3 having a diameter of 1.0 mm were formed using an NC drill. As a method of forming the through holes 3, it is considered that a method using a YAG laser and a method using a water flow cutter are effective.

Next, as shown in FIG. 1C, a through hole inner wall insulator 4 is formed on the inner wall of the through hole 3. After removing the debris generated in the previous step, degreasing treatment and thin nickel plating on the exposed part of the iron plate on the inner wall of the through hole,
Using an electrophoretic method, deposit the ceramic to about 900
The through hole inner wall insulator 4 is formed by firing at 1 ° C. for 1 hour. The thickness of the through hole inner wall insulator 4 is about 200 μm at the center of the through hole cross section.

Finally, as shown in FIG. 1D, through-hole metallization is performed on the through-hole 3 with the conductor 5.

In the first embodiment, since the insulator has the same thickness as that of the flat portion in and around the through hole,
As shown in Table 1, the withstand voltage between the metal pattern and the wiring pattern for connecting the front surface and the back surface could be sufficiently increased. N
Is the number of through holes.

[0012]

[Table 1]

FIG. 2 is a cross-sectional view of the second embodiment of the present invention, in which the manufacturing steps are arranged in the order of (a) to (e).

First, as shown in FIGS. 2A and 2B, a ceramic 2 is formed around an iron plate 1 and a through hole 3 is formed. This is similar to the case of FIGS. 1 (a) and 1 (b).

Next, as shown in FIG. 2 (c), the first through-hole insulator 6 is formed by using the screen printing method, and as shown in FIG. 2 (d), the surface opposite to the previous step is formed. The second through-hole insulator 7 was formed by using a screen printing method.

Finally, through-hole metallization was performed using the conductor 5 to connect the front and back wiring patterns.

In the second embodiment, similar to the first embodiment, the withstand voltage between the wiring in the through-hole metallized portion and the metal plate can be improved, and the steps after the insulator formation in the through-hole are performed. All became screen printing processes, increasing the degree of freedom in design and manufacturing.

[0018]

According to the present invention, after an insulator is formed around a metal plate, a hole penetrating the front and back is formed, an insulator is formed on the inner wall of the through hole, and then through-hole metallization is performed. Therefore, the withstand voltage between the wiring pattern including the through-hole metallized portion and the metal plate is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a process of an example of the present invention.

FIG. 2 is a cross-sectional view showing a process of another embodiment of the present invention.

[Explanation of symbols]

 1 Iron Plate 2 Ceramic 3 Through Hole 4 Through Hole Inner Wall Insulator 5 Conductor 6 First Through Hole Insulator 7 Second Through Hole Insulator

Claims (2)

[Claims] 1. A metal core substrate with a through hole, which comprises a metal plate, an insulator formed around the metal plate, and a plate film portion covering the insulator, wherein the surface of the metal plate is insulated. A through-hole metal core substrate, characterized in that a plurality of through-holes are provided in the metal plate after applying a body, an insulator is applied to an inner side wall of the through-hole, and through-hole metallization is performed. 2. In a metal core substrate with a through hole, which comprises a metal plate, an insulator formed around the metal plate, and a thick film portion covering the insulator, the surface of the metal plate is insulated. After applying the body, a plurality of through holes are provided in the metal plate, and a first insulator is applied to an inner side wall of the through hole by a screen printing method, and then the first insulator is covered. A further through hole metal core substrate is formed by further forming a second insulator and performing through hole metallization.