JPH0629660A - Manufacture of multilayered wiring board - Google Patents

Abstract

PURPOSE:To reduce cost by forming a fine pattern by using conductive paste for connecting an nth layer with an (n+1)th layer. CONSTITUTION:A conductor wiring circuit 12 as a first layer is formed by screen printing conductive paste on a glass or ceramic substrate 11 and baking the paste. Conductive paste for connecting the first layer with a second layer is printed, and a film 13 of conductive paste is formed by drying or baking after drying. Insulative paste is printed as a pattern having a viahole larger than or equal to the film 13 of conductive paste, and a film 14 of insulative paste is formed by drying or baking after drying. Conductive paste is printed on the film 13 of conductive paste and the film 14 of insulative paste, and a conductor wiring circuit 15 as a second layer is formed by baking after drying. If necessary, the above process is repeated and a wiring board having more layers can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board used in various electronic equipment such as computers, AV equipment and communication equipment.

[0002]

2. Description of the Related Art Conventionally, there are roughly two types of multi-layer wiring boards using glass or ceramics of this kind as a base material. That is, one is a printed multilayer wiring board obtained by alternately printing and firing a conductive paste and an insulating paste on a glass or ceramic substrate (the firing may also be performed collectively at the end), and the other is a ceramics Alternatively, it is a so-called green sheet multilayer wiring board in which a conductive paste is printed or embedded on a green sheet of glass ceramics and in a via hole is laminated and pressed and fired.

Of these two, the former is used in various electronic devices by taking advantage of its dimensional stability and low cost. A cross-sectional view of a conventional method for manufacturing a printed multilayer wiring board is shown in FIG. 2 and will be described below.

First, as shown in FIG. 2A, a conductive paste is screen-printed on a glass or ceramic substrate 21 and fired to form a first-layer conductor wiring circuit 22.
Next, as shown in FIG. 2B, the insulating layer 23 having via holes is formed.
Is formed by screen-printing an insulating paste containing glass or ceramics as a main component, baking after drying, and further forming a conductive wiring circuit 24 of the second layer as shown in FIG. 2C. Is printed and formed by firing. The firing of the insulating paste and the firing of the second-layer conductive paste may be performed simultaneously. By repeating this, a multilayer wiring board is manufactured as shown in FIG.

[0005]

However, the above-mentioned conventional method for manufacturing a multilayer wiring board has the following problems. Film thickness after firing insulating layer having via holes 5 to 50
In the case of forming to a thickness of about μm, in a generally used screen printing, there is a phenomenon that fine via holes are filled up due to bleeding of the insulating paste after printing and melting or flowing of the glass component in the insulating paste during firing. Happened,
The diameter of the via hole is the minimum diameter of a round hole that can be manufactured with a good yield and the length of one side of a square hole is about 200 to 250 μm, and it is very difficult to form a small via hole of 200 μm or less. is there. This is a problem that hinders the densification of the multilayer wiring board and further hinders downsizing of electronic devices.

To solve this problem, in recent years, a method of printing and drying an insulating paste on the entire surface and forming fine via holes by melting and scattering an insulating paste film in a portion irradiated with a laser beam, and the insulating paste on the entire surface When printing and drying, and then printing a paste with a special composition in a pattern equal to the diameter of the via hole, it penetrates into the insulating paste dry film, and by development, the penetrating portion of the paste with a special composition is dissolved and removed to make it fine. A method for obtaining a large via hole is being developed. However, these methods have other problems such as requiring a laser device, a developing process, a special material, being expensive, and limiting the application range.

The present invention solves this problem, and provides a method for manufacturing a multilayer wiring board, in which a fine via hole having a via hole diameter of 200 μm or less, particularly 100 μm or less, can be formed at a low cost in a process which is almost the same as the conventional manufacturing method. Is what you are trying to do.

[0008]

To achieve this object, the present invention prints a conductive paste for connecting the nth layer and the (n + 1) th layer on the nth layer (n ≧ 1) conductor. A step of forming an insulating paste for forming an insulating layer between the nth layer and the (n + 1) th layer by printing as a pattern having a via hole having a size equal to or larger than that of the conductive paste film; It includes a step of forming a conductive paste for conductor of the (n + 1) th layer by printing.

[0009]

The present invention has the function of forming fine via holes as described below because it includes the above steps. That is, before printing the insulating paste for forming the insulating layer between the nth layer and the (n + 1) th layer, the conductive paste for connecting the nth layer and the (n + 1) th layer is printed in the form of fine dots. By drying, or drying and baking, the conductive paste film acts as a breakwater even if bleeding after printing the insulating paste or melting of the glass component in the insulating paste during baking occurs, and the n-th layer And the (n +
1) The electrical connection of the layers can be ensured. Compared with printing of insulating paste having a via hole pattern,
By using a metal screen plate or the like as a conductive paste for connecting the layer and the (n + 1) th layer, a dot-like pattern having a diameter of 100 μm or less can be formed relatively easily, and as a result, a fine via hole having a diameter of 100 μm or less can be formed. The multi-layer wiring board having the above can be manufactured at low cost without requiring a special process.

[0010]

EXAMPLE A manufacturing method according to an example of the present invention will be described below.

First, the process of the present invention will be described with reference to FIG. A glass or ceramic substrate 1 as shown in FIG.
Conductive paste is screen-printed on top of 1 and fired to
The conductor wiring circuit 12 of the layer is formed. Next, a conductive paste for connecting the first layer and the second layer is printed and dried or dried and then baked to form a dried or baked film 13 of the conductive paste. Next, the insulating paste is printed as a pattern having a via hole having a size equal to or larger than that of the conductive paste film 13 and dried or dried and then baked to form a dried or baked film 14 of the insulating paste. Next, the conductive paste is printed on the films 13 and 14 of the conductive paste and the insulating paste, dried and baked to form the second-layer conductor wiring circuit 15. If necessary, by repeating this, a multilayer wiring board can be manufactured.

Next, a concrete example will be shown. (Example 1) An Ag-Pd paste was screen-printed on an alumina substrate and baked at 850 [deg.] C. to form a first-layer conductor wiring circuit.
It was printed in a rod shape in a size of 00 μm square so that the baked film thickness was 40 μm, and dried.

Next, using a screen plate having a 150 μm square via hole pattern. Printing and drying of the glass paste were repeated twice to obtain a baked film thickness of 30 μm, and bleeding immediately after printing resulted in a shape in contact with the Ag-Pd dry film as shown in FIG. This 8
After firing at 50 ° C, Ag-P is further deposited on the fired film.
The d paste was screen-printed and fired at 850 ° C. to form a second-layer conductor wiring circuit. The above steps were repeated twice more to manufacture a four-layer wiring board having 100 μm square via holes.

Example 2 An Au resinate paste was screen-printed on an alumina substrate and fired at 850 ° C. to form a conductor wiring circuit of the first layer, and a resistor paste containing RuO ₂ as a main component. Was printed so as to have a baked film thickness of 30 μm in a size of 80 μm square, dried, and baked at 850 ° C.

Next, using a screen plate having a 200 μm square via hole pattern, printing and drying of a glass paste containing a glass powder having a softening point of 700 ° C. as a main component were repeated twice to obtain a baked film thickness of 20 μm. I chose At this time, due to bleeding immediately after printing, the via hole diameter of the glass paste dry film becomes 100 to 150 μm. Although it is not in contact with the RuO ₂ paste film, when it is baked at 850 ° C., it has a softening point of 70, which is the main component in the glass paste dry film.
Since the glass powder at 0 ° C. melts and flows, the finished glass fired film is in the state shown in FIG. 1 in which it is in close contact without being covered with the RuO ₂ fired film. Furthermore, A
80 μm by printing u resinate paste by screen printing and baking at 700 ° C. to form the second layer conductor wiring circuit.
A two-layer wiring board having corner via holes was manufactured.

Besides the substrates and paste materials shown in Examples 1 and 2, the following materials are used. As the substrate, in addition to the alumina substrate, a glass substrate, a mullite substrate, a quartz substrate, a silicon substrate, an aluminum nitride substrate, a ferrite substrate, or the like can be used. Examples of the conductive paste for conductor wiring circuit include Ag-Pd paste, Au resinate paste, Ag paste, Au paste, Cu paste, and P.
One or more kinds of various thick film circuit forming pastes such as d paste, metal organic compound (resinate) pastes such as Ag resinate, Cu resinate, organic acid In and organic acid Sn can be used. As the conductive paste for connecting the nth layer and the (n + 1) th layer, various thicknesses of Au paste, Ag paste, Cu paste, Pd paste, SnO ₂ paste, etc. other than Ag-Pd paste and RuO ₂ paste are used. The film circuit forming paste and the thick film resistor forming paste can be used as they are. The insulating paste between the nth layer and the (n + 1) th layer may be glass paste, alumina,
A glass ceramic paste containing a ceramic filler such as mullite, or a paste containing an alkoxide, which becomes silica, alumina or the like when dried and fired, as a main component can also be used.

Further, construction methods other than those shown in Examples 1 and 2 can also be used. For example, in order to form a pattern of a conductive paste or a glass paste, the first and second embodiments are generally used.
Although the screen printing method shown in 1 is used, offset printing, gravure printing, or the like can also be used. Regarding the firing temperature and firing atmosphere, conditions suitable for each used material other than those shown in Examples 1 and 2 can be used.

[0018]

As is apparent from the above embodiments, the method of manufacturing a multilayer wiring board according to the present invention has the following effects. That is, by forming a fine pattern with a conductive paste for connecting the nth layer and the (n + 1) th layer, bleeding of the insulating paste and filling of the via hole due to firing are eliminated, and the via hole diameter is 200 μm or less, particularly 10 μm.
A multi-layer wiring board with via holes with a diameter of 0 μm or less can be manufactured at low cost without requiring special steps other than the conventional screen printing, drying, and baking steps, contributing to higher board density and smaller electronic devices. There is a big place to do.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method for manufacturing a multilayer wiring board according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional method for manufacturing a multilayer wiring board.

[Explanation of symbols]

 11 Ceramic Substrate 12,15 Conductor Wiring Circuit 13,14 Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Mohri 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. When a conductive paste and an insulating paste are alternately printed and fired on a glass or ceramic substrate to obtain a multilayer wiring substrate, the nth layer and the nth layer are formed on the nth layer conductor (n ≧ 1). Forming a conductive paste for connecting the (n + 1) th layer by printing, and forming an insulating paste for forming an insulating layer between the nth layer and the (n + 1) th layer into a via hole having the same or more shape as the conductive paste film. A method of manufacturing a multilayer wiring board, comprising: a step of forming a pattern having a pattern by printing; and a step of forming a conductive paste for a conductor of the (n + 1) th layer by printing.