JPS62254491A - Enamelled board for printed wiring board and manufacture of the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an enameled substrate for printed wiring boards and a method for manufacturing the same.

[Prior Art and Problem 1 Generally, substrate materials used for printed wiring boards are mainly resin materials and ceramic materials. The basic functions of printed wiring boards are insulation, conductivity, and component support, and there is no room for the use of metal plates such as iron.

However, metal plates such as iron have properties unique to metals, such as strength, thermal conductivity, and electromagnetic shielding properties.

Therefore, in order to obtain a printed wiring board that particularly requires such characteristics, a so-called metal-based insulating substrate, in which the surface of a metal plate is insulated, is sometimes used instead of a resin material or ceramic material as the substrate material. . Enamel substrate is one of these metal-based insulating substrates.
It is well known that this enamel substrate has particularly excellent electrical insulation and heat resistance.

Now, when manufacturing a C printed wiring board using such an enamel substrate, conventionally, an enamel layer is formed on the surface of a metal core material, and a enamel layer is placed on the surface of the enamel layer. ! To form a circuit, conductive paint was printed and then baked to form a wiring circuit.

The reason why conductive paint is used to form wiring circuits is that, for example, when copper foil is placed on the enamel and fired, the enamel is sandwiched between the copper foil and the base metal plate, making it impossible to release gas during firing, which prevents the enamel from being a good insulator. thing,
Furthermore, if the copper foil is bonded with an adhesive made of aluminum, the resulting printed circuit board will have poor heat resistance.

Therefore, for this reason, in the conventional method of manufacturing a printed wiring board using an enamel substrate, a highly accurate wiring circuit cannot be formed because the wiring circuit is formed by printing conductive paint. Another problem is that the electrical characteristics of the wired circuit conductor are inevitably inferior to those of a conductor made of metal foil such as copper foil. Moreover, special elements are usually added to conductive paints used for enamel in order to improve VB adhesion to the enamel, but these elements generally do not affect the electrical conductivity of wiring circuit conductors. Furthermore, in the conventional method (printing method), which deteriorates the characteristics, there is a problem in that there is a limit to the formation of recent micron-order wiring circuits.

[Object of the Invention] In view of the above, the object of the present invention is to provide a novel enamel substrate for a printed wiring board, in which formation of a wiring circuit is easy and economical, and adhesion to enamel can be significantly improved, and a method for manufacturing the same. Our goal is to provide the following.

[Summary of the invention l That is, the gist of the present invention is to form an enamel layer on the surface of a gold a core material, and to form a thin metal film layer on the surface of the enamel layer by metallizing a part of the enamel layer. In addition, by forming a metal plating layer on the thin metal film layer, the enamel substrate for a printed wiring board can be constructed with sufficiently low conductor resistance. be.

Furthermore, the gist of the present invention is to provide an oxide or suboxide of a suspended metal on the surface of the metal core material, in which metal atoms that are not incorporated into the network structure of glass ceramics can exist as modifying ions in the same structure. A reducing atmosphere containing a vacuum is introduced near the flow temperature of the enamel during or after the firing, and the product is cooled while maintaining this reducing atmosphere. Possibly a thin film of the above metal on the surface of the enamel! A method for manufacturing an enamel substrate for a printed wiring board in which a J layer is formed, and an enamel substrate for a printed wiring board in which a metal plating layer is formed on the metal thin film layer! yJ manufacturing method, and a method for manufacturing an enameled substrate for a printed wiring board, in which a portion of the metal thin film layer other than the portion that will become the wiring circuit is removed by etching, and then a metal plating layer is formed on the portion that will become the wiring circuit. It is in.

In the present invention, a reduced film of a specific metal, which is preliminarily contained in the enamel in the form of an oxide or suboxide, is formed on the surface of the enamel, and this reduced film is used to effectively and adhesively adhere to the surface of the enamel. It is based on an extremely innovative technical idea of creating an excellent wiring circuit. In response to this technical philosophy, although it is not an enameled board for printed wiring boards,
There is a technical idea to make the enamel itself semi-conductive by firing the enamel at an elevated temperature in a reducing atmosphere.

However, this technical idea is to make the entire enamel semiconductive, not to make only the surface of the enamel thin and conductive. Therefore, it goes without saying that the above technical idea cannot be applied to the present invention as it is.

In other words, in the case of enamel substrates for printed wiring boards, the enamel naturally functions as an insulator, so if the entire enamel were to be made semiconductive, the function of the enamel as an insulator would be lost. This is because the very structure of the printed wiring board will be denied.

In the method of manufacturing an enameled substrate for printed wiring boards of the present invention, first, metal oxides or suboxides are added in an amount such that metal atoms that are not incorporated into the network structure of the glassy ceramic can exist as 6m ions in the network structure. It is necessary to prepare enamel made by adding. The crystal structure of vitreous ceramics has a regular or irregular network structure.
It is known that certain metal ions are not incorporated into this network structure and exist as modified ions (also called network modified products).

Such metals include 7n, 13a, W,
M.O.

There are metals such as 3n, and the enamel according to the present invention is made by adding a considerable amount of these metals in the form of oxides or suboxides. The term "considerable amount" refers to the range in which a reduced film is formed by the method described later, and the range is not particularly limited.

For example, examples of oxides of metals such as Zn, Ba, W, MO, and 3n include Zno, WO3, and MoOx.

Examples include Sn02.

Next, in the manufacturing method of the present invention, enamel added with a specific metal oxide or suboxide as described above is applied to the surface (the entire surface or one side may be) of the metal core material.
The material is melted and fired at a temperature of 00 to 1000° C. During or during firing, a reducing atmosphere including vacuum is introduced around the vJ temperature of the enamel flow, and the material is rapidly cooled while maintaining this reducing atmosphere. As a result, a thin reduced metal film is formed on the surface of the enamel that has been solidified by cooling.

This is a thin layer of metal. Here, it is preferable to introduce a hydrogen gas atmosphere as the reducing atmosphere.

Further, it is preferable that the cooling is performed as quickly as possible without causing cracks.

As a result, a thin reduced film of, for example, 1 μm or less can be easily formed on the surface of the enamel.

Furthermore, by using a mask at this time, a reduced film can be selectively formed, and a wiring circuit can be formed simultaneously with the formation of the reduced film.

Although the metal thin film layer formed by this method has excellent adhesion to heat-conducting enamel, its properties as an electrical conductor are often insufficient.

Therefore, in order to ensure and improve the C properties of this metal film as a conductor, the present invention further provides a metal plating layer on the gold AASV by electrolysis or electroless method. Here, as the metal to be plated, for example, Cu,
Metals such as Ni, Su, and Ag are used.

Furthermore, when a wiring circuit is formed using the above-mentioned thin III layer of metal, the present invention performs this by etching. In etching, for example, a photosensitive resin for a mask is applied onto a thin metal film layer formed on the surface of enamel, and a pattern mask is placed on top of it, exposed and developed, leaving the wiring circuit and removing the other parts of the metal. A fine and accurate wiring circuit can be formed by the so-called photo-etching method, in which the thin film layer is removed by etching. Of course, the etching can be performed by a general etching method instead of the photo etching method.

Further, if the peeling layer itself has wiring @4 paths formed therein, this etching can be omitted.

[Embodiment 1] Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows one embodiment of the invention, and FIG. 2 shows another embodiment of the invention.

1 and 2, 1 is an iron plate having a thickness of 111 which is a metal core material, 2 is an enamel layer formed on the entire surface of the iron plate 1, and 3 is an enamel layer 2 on the surface of this enamel layer 2. Metal 1 formed by metallizing a part of the surface of
1111Jffl.

Here, the thickness of the enamel 112 is 0.15+e■, and the thickness of the metal thin film F43 formed on the surface of the enamel Ff/12 is 0.2 μm. Or 4 is the metal thin film W
! This is an electroless plating layer of copper metal formed on J3.

The thickness of the plating layer is 10μ.

Now, here are Figure 1 (4), (b), and (c).

To explain the manufacturing method of the enamel substrate for printed wiring boards shown in (4), first, both the iron plate 1 and the S! Oz'
-Pb 0-8z 5 to 7fflf to the three-component system of O3
Enamel (glaze) is prepared by adding 3% of ZnO metal oxide to a glass composition which is easily reduced and which is made by adding fi% of 5bzO3.

Then, enamel (glaze) is applied to the surface of the iron plate 1, and this is melted and fired at a temperature of 850°C. Transfer this to a reduced pressure container that forms a reducing atmosphere, and in this container
At a temperature around 0°C, hydrogen gas is introduced and at the same time the container is depressurized. This state is held for about 30 seconds, then rapidly cooled, and as the enamel layer 2 solidifies, a 0.2 μm thick layer is formed on its surface.
A 111 layer 3 of Zn metal is formed. Incidentally, this thin I of Zn metal! The surface resistance of the first layer 3 is 10Ω/c+e.

Next, a photo-etching method is applied to leave a portion of the N film layer 3 of znat which is to become a wiring circuit, and remove the rest by etching. Since the thin film [13] is as thin as 0.2 .mu.m, it can be sufficiently removed by etching of several .mu.m or less. As a result, copper metal is electrolessly plated on the peeling layer 3 on which a fine wiring circuit has been formed, and plating ll! With the formation of step 4, the enamel substrate 5 for printed wiring board is completed.

Next, the method for manufacturing the enamel substrate for printed wiring boards shown in FIG. 2 (a), (U), and (c) will be explained.
Enamel (glaze) having the composition used in FIG. 1 is applied to the surface of the iron plate 1 and then melted and fired. Then, this was transferred to a vacuum container that forms a reducing atmosphere, hydrogen gas was introduced into the container at a temperature of approximately 830°C, the container was simultaneously reduced in J, and after being held in this state for 30 seconds, it was rapidly cooled. , 7n metal thin film 1ffi on the surface of the enamel layer 2
At this time, the Znn metal film layer 3 is selectively formed by applying a mask to the surface of the pre-fired enamel layer when transferring it to the container. As a result, simultaneously with the solidification and formation of the enamel WJ2, the formation of the 7n metal peeled film FFJ3 and the formation of the wiring circuit are simultaneously performed. Then, electroless plating of copper metal is performed along this wiring circuit, and with the formation of a plating layer 4, a flying pattern for a printed wiring board is completed.

The formation of the copper metal plating layer 4 is very effective in improving the conductive properties of the wiring circuit. In other words, the electrical properties of the copper metal plating layer are similar to those of electrolytic copper foil, and can be said to be extremely superior to conventional conductors made of conductive paint.

[Effects of the Invention] As described in (5) below, the enamel substrate for printed wiring boards and the manufacturing method thereof of the present invention have the following remarkable effects.

(1) By forming a metal kDrh layer on the surface of the enamel layer by metallizing a part of the surface of the enamel layer, a mechanically sound enamel substrate with excellent adhesion of the metal to the enamel layer is created. Obtainable.

(2) By forming a metal plating layer on the metal thin film layer described above, the electrical properties of the wiring conductor are improved, and as a result, the conventional enamel board in which the wiring conductor was formed using 39ffi paste It is possible to solve the major drawback of 1 and obtain an electrically superior enamel substrate.

(3) A thin film layer of a specific metal, which is previously contained in the enamel in the form of an oxide or suboxide, is formed on the surface of the enamel by reduction, and a wiring circuit is formed based on this thin film layer. It is easy to form circuits, and in particular, the method of forming a thin film layer on the surface at the same time as firing the enamel makes the process of forming wiring circuits efficient and economical, and can greatly contribute to lowering the cost of enamel substrates. can.

(4) Conventional enamel substrates had wiring circuits formed by screen printing conductive paint on the surface of the enamel, so there was a limit to miniaturization and accuracy of wiring with such printing methods, but the present invention By employing an etching method, particularly by applying a photoetching method, it is possible to easily form a fine and accurate wiring circuit.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the enamel substrate for printed wiring and its manufacturing method according to the present invention, and FIG. 2 is an explanatory diagram of another embodiment according to the present invention. 1... Iron plate. 2... Floating layer. 3...ZnfL thin film layer. 4... Copper metal plating layer. Agent Patent Attorney Bo 1) Ri Kosan 10 Kanzea 1 Kim 0 Anz 1 ¥ Urou 1 3 zn Gimhae 1 aL! L4 Now gold and reward & 1! , to Δ

Claims (5)

[Claims] (1) A printed wiring board characterized by forming an enamel layer on the surface of a metal core material, and forming a thin metal film layer on the surface of the enamel layer by metallizing a part of the enamel layer. Enamel board for use. (2) Forming an enamel layer on the surface of the metal core material, forming a thin metal film layer by metallizing a part of the enamel layer on the surface of the enamel layer, and plating the metal on the thin metal layer. An enameled substrate for printed wiring boards characterized by forming layers. (3) A metal oxide or suboxide is added to the surface of the metal core material in an amount that allows metal atoms that are not incorporated into the network structure of the glassy ceramic to exist as modifying ions in the network structure. Naru enamel is applied and melted and fired,
During or after this firing, a reducing atmosphere including vacuum is introduced near the flow temperature of the enamel, and by cooling quickly while maintaining this reducing atmosphere, a thin film of the above-mentioned metal is formed on the surface of the enamel. A method for manufacturing an enameled substrate for a printed wiring board, characterized by: (4) A metal oxide or suboxide is added to the surface of the metal core material in an amount that allows metal atoms that are not incorporated into the network structure of the glassy ceramic to exist as modifying ions in the same structure. Enamel is applied, melted and fired, and during or after firing, a reducing atmosphere including vacuum is introduced near the flow temperature of the enamel, and by cooling while maintaining this reducing atmosphere, the surface of the enamel is heated. A method for manufacturing an enameled substrate for a printed wiring board, comprising forming a thin film layer of the metal described above, and forming a plating layer of metal on the thin film layer of the metal. (5) A metal oxide or suboxide is added to the surface of the metal core material in an amount that allows metal atoms that are not incorporated into the network structure of the glassy ceramic to exist as modifying ions in the same structure. Naru enamel is applied and melted and fired,
During or after this firing, a cyclic atmosphere containing vacuum is introduced near the flow temperature of the enamel, and by cooling while maintaining this reducing atmosphere, a thin film layer of the above-mentioned metal is formed on the surface of the enamel. , manufacturing an enamel substrate for a printed wiring board, characterized in that the portions of the thin metal film layer other than the portions that will become the wiring circuit are removed by etching, and then a metal plating layer is formed on the portions that will become the wiring circuit. Method.