JPH0513903A - Metal core substrate and manufacture there0f - Google Patents

Abstract

PURPOSE:To provide a metal core substrate having high dielectric withstand voltage in its through hole part. CONSTITUTION:After an insulating layer, consisting of a crystallized glass layer 1, is additionary formed in the through hole 2 of a metal core substrate, having an insulating layer 5 formed on the circumference of a metal plate 4, and on the circumference of the through hole 2, a through hole metallized layer 6 is formed. As an insulating layer, consisting of a crystallized glass layer 1, is additionally formed in the through hole 2 and its circumference as above-mentioned, the dielectric withstand voltage between the through hole metallized layer 6 and the metal plate 4 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal core substrate and a manufacturing method thereof, and more particularly to a metal core substrate on which electronic parts are mounted and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional metal core substrate has a through hole, and a metal plate having a chamfered end face and a vertical cross section of the through hole is prepared by suspending a powder of an inorganic insulating material in a solvent and charging the powder particles. Immerse in a solution, attach an insulator around the metal plate by electrophoresis, and bake at 900 ° C for 1 hour to 100-20
An insulating layer having a thickness of 0 μm is formed. Next, using a screen printing method or the like on this insulating layer, a metal core substrate in which a wiring pattern and a through-hole metallized layer are formed by a thick film conductor layer of silver palladium or the like, and then a resistor layer, a protective glass layer, etc. are sequentially formed. Met.

In such a conventional metal core substrate, due to the nature of the electrophoretic method, it is difficult for the insulator to adhere to a narrow portion such as the inside of the through hole, and the inside and the periphery of the through hole during baking at about 900 ° C. for 1 hour. Since the insulator formed on the curved surface of the substrate and the edge of the substrate softens and flows, the thickness of the insulating layer in and around the through-hole is 1
It becomes / 2-1 / 4.

[0004]

In the insulating layer formed and baked by the conventional electrophoretic method of the metal core substrate, in the inside and around the through hole, it is 1/2 to 1/1 / third of that of the flat portion.
Therefore, when forming the through-hole metallized layer and connecting the wiring patterns on the front surface and the back surface, the dielectric strength between the metal plate and the metal plate is insufficient.

An object of the present invention is to provide a metal core substrate having an excellent dielectric strength between a through-hole metallized layer and a metal plate, and a method for manufacturing the same.

[0006]

(1) The present invention provides a metal plate, an insulating layer formed on the surface of the metal plate and the inner surface of the through hole, a conductor layer formed on the insulating layer, and a through hole. In a metal core substrate having a hole metallized layer, a resistor layer, and a protective glass layer, an insulating layer is formed between the through hole and the insulating layer around the through hole and the through hole metallized layer. .

(2) In the method of manufacturing a metal core substrate of the present invention, a step of forming a through hole in a metal plate, and forming an insulating layer on the surface of the metal plate and the inner surface of the through hole by an electrophoretic method and baking. A step of forming an additional insulating layer on the inner surface and the periphery of the through hole on the insulating layer by screen printing and firing, and a step of forming a through-hole metallized layer on the insulating layer. including.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.

1 (a) and 1 (b) are configuration diagrams of an embodiment of the present invention, in which (a) is a plan view and (b) is its AA 'line.
It is a line sectional view.

As shown in FIGS. 1 (a) and 1 (b), in the metal core substrate in which the insulating layer 5 is formed around the metal plate 4, a thin portion of the insulating layer 5 is partially formed inside the through hole 2. ing. Crystallized glass is screen-printed in and around the through-hole 2 so as not to compensate for the thin portion of the insulating layer 5 while sucking the through-hole 2 from the back side of the printing surface to form on both sides. Then, firing is performed at 850 ° C. to form the crystallized glass layer 1. At this time, the crystallized glass layer 1 is formed to have a thickness of about 40 μm.
Then, the through hole metallization layer 6 and the wiring pattern are formed on the conductor layer 3.

By forming the crystallized glass layer 1 in and around the through hole 2, the conductor layer 3 and the metal plate 4 are formed.
It was possible to improve the insulation withstand voltage.

[0012]

As described above, according to the present invention, since the insulating layer is selectively formed in and around the through hole,
This has the effect of improving the dielectric strength voltage between the through-hole metallization layer and the metal plate.

As an example, when the thickness of the insulating layer around the metal plate is about 120 μm, the thickness of the insulating layer in the through hole portion is about 50 μm, and the withstand voltage at this time is about 500 DC.
It was V. When an additional insulator was selectively formed in and around the through hole, the dielectric strength was about 1000V DC.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

1 Crystallized glass layer 2 through holes 3 conductor layers 4 metal plate 5 insulating layers 6 Through hole metallization layer

Claims (2)

[Claims] 1. A metal plate, an insulating layer formed on a surface of the metal plate and an inner surface of a through hole, a conductor layer formed on the insulating layer, a through-hole metallized layer, a resistor layer, and a protective layer. A metal core substrate having a glass layer, wherein an insulating layer is formed between the through hole and the surrounding insulating layer and the through hole metallized layer. 2. A step of forming a through hole in a metal plate; a step of forming an insulating layer on the surface of the metal plate and an inner surface of the through hole by an electrophoretic method and baking; and a step of forming the through hole on the insulating layer. Manufacture of a metal core substrate characterized by including a step of selectively forming an additional insulating layer on the inner surface and the periphery of the hole by a screen printing method and firing, and a step of forming a through-hole metallized layer on the insulating layer. Method.