JPH07302957A - Thick film circuit board and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a thick film circuit board operable with heavy-current and having a thick film conductor which does not generate a short circuit with an adjacent metallization pattern, and manufacture thereof. CONSTITUTION:A thick film circuit board is constituted by a heat resistant base 1, and thick film conductors 2 and 3 of predetermined metallization patterns formed on the base 1. A part of the thick film conductors 2 and 3, for example, the thick film conductor 2 is constituted by a thick film shape film 21 for restricting the shape of the predetermined metallization pattern and a thick film conductor film 22 arranged in a region surrounded by the thick film shape film 21. The thick film conductor film 22 is formed by supplying conductive paste in the region surrounded by the thick film shape film 21, then drying and burning the paste.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a ceramic single plate substrate,
The present invention relates to a thick film circuit board in which a thick film conductor having a predetermined pattern is formed on the surface of a heat resistant substrate such as a ceramic laminated board, and more particularly to a thick film circuit board compatible with low resistance or large current and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a thick film circuit board is formed by printing a conductive paste such as Ag or Cu on a surface of a ceramic single plate substrate by screen printing in a predetermined shape.
It was dried and fired to form a thick film conductor having a predetermined pattern, and then various electronic parts were mounted.

In such a thick film conductor having a predetermined wiring pattern, for example, a thick film conductor serving as a power supply line or a ground line in a predetermined circuit network has a large current flowing therein, and therefore, it is necessary to increase the allowable current of the thick film conductor. There is.

As a method for increasing the allowable current of the thick film conductor, the width of the thick film conductor is widened, or the printing of the conductive paste is repeated a plurality of times to increase the film thickness. There was a solder coat on the surface.

[0005]

However, widening the thickness of the thick film conductor violates the demand for high-density wiring.
The entire board becomes large.

Further, if the printing of the conductive paste is repeated a plurality of times to increase the thickness of the thick film conductor, the number of times of printing increases, the printing / drying process becomes complicated, and the thick film is thick. Although it depends on the width of the conductor, the number of times of repeated printing is limited, and it is difficult to achieve a predetermined thickness. Furthermore, when printing is repeated, sagging of the paste occurs, which causes a problem such as a short circuit between wiring patterns.

Further, the solder coating of the surface of the thick film conductor requires a different process of solder coating, and moreover, a solder bridge is apt to occur between adjacent wiring patterns, which greatly restricts the subsequent heat treatment process. There was a problem such as giving.

The present invention has been devised in view of the above problems, and an object thereof is to provide a thick film conductor having a thick film conductor capable of handling a large current and not causing a short circuit with an adjacent wiring pattern. It is to provide a membrane circuit board and a manufacturing method thereof.

[0009]

According to the first invention, in a thick film circuit board formed by forming a thick film conductor having a predetermined wiring pattern on a heat resistant substrate, the thick film conductor is partially formed. A thick film circuit board having a thick film conductor film formed inside a frame-shaped thick film outer film.

According to the second aspect of the present invention, a step of forming a frame-shaped thick film contour film on the heat resistant substrate by printing and baking an insulating glass paste, and a step of forming the frame-shaped thick film contour film inside the frame-shaped thick film contour film. And a step of forming a thick film conductor film by filling with a conductive paste and baking the conductive paste.

According to the third invention, a step of forming a frame-shaped thick film outer shape resin film by printing and curing a resin paste on the heat resistant substrate, and the frame-shaped thick film outer shape resin. A method for manufacturing a thick film circuit board, comprising: a step of filling a conductive paste inside a film and forming a conductor to be a thick film conductive film by drying; and a step of baking the conductor.

According to the fourth invention, a step of forming a frame-shaped thick film outer shape resin film by printing and curing a resin paste on the heat resistant substrate, and the frame-shaped thick film outer shape resin. Inside the film, a step of filling a conductive paste and forming a conductor to be a conductor film by drying, a step of dissolving and removing the thick film outer shape resin film, and a step of baking the conductor, A method of manufacturing a thick film circuit board including:

[0013]

According to the first aspect of the invention, among the thick film conductors on the substrate, a thick film conductor through which a substantially large current flows is regulated, and a thick film conductor film and the outer shape of the thick film conductor film are regulated. And a thick film outer shape film formed in a frame shape. Therefore, even if the thickness of the thick-film conductor film is increased to increase the allowable current, the width of the conductor is regulated by the thick-film outer shape film, so that it is possible to prevent a short circuit with an adjacent thick-film conductor.
High-density wiring can be realized, and a thick film conductor through which a large current flows can be easily formed.

According to the second to fourth inventions, the thick film conductor film is provided with the conductive paste in the region surrounded by the frame-shaped thick film outer shape film formed prior to the formation of the thick film conductor film. Since it is formed by filling, drying and baking, the supply of the conductive paste forms a stable thick film conductor without the conductive paste dripping due to the presence of the thick film outline film and short-circuiting to the adjacent conductor. be able to.

Further, by increasing the supply amount of the conductive paste, it is possible to easily increase the thickness of the thick conductive thick film through which the current flows.

The thick film outer shape film of the second invention remains on the thick film circuit board even after firing.

Further, in the third to fourth inventions, the thick film outer shape film is formed of a resin paste, and in the third invention,
The resin-made thick film outer shape resin film is burned off at the same time as the firing of the thick film conductor film. In the fourth invention, the resin thick film outer shape resin film is a conductive film that becomes a thick film conductor film. After being filled and dried with a conductive paste, it is dissolved and removed with a solvent. That is, when the conductive paste to be the conductive thick film conductor film is finally fired, the thick film outer shape resin film does not remain on the thick film circuit board.

Therefore, a space corresponding to the area where the thick film outer shape resin film was formed is generated between the adjacent thick film conductors, and a short circuit with the adjacent thick film conductors is completely prevented. can do.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.
It should be noted that the embodiments will be described by using a thick film circuit board using a single plate-shaped ceramic substrate.

FIG. 1 is a plan view for explaining the first invention, and FIG. 2 is a sectional view taken along line XX in FIG.

In FIG. 1, 1 is a heat resistant substrate,
2 and 3 are thick film conductors including terminal pads and electronic component mounting pads. In particular, the thick film conductor 2 includes the thick film outer shape films 21, 21.
And a thick conductor film 22.

The heat resistant substrate 1 may be, for example, a single plate-shaped ceramic substrate such as alumina, aluminum nitride or mullite. Hereinafter, the heat resistant substrate is referred to as a ceramic substrate.

The thick film conductor 2 is a conductor through which a relatively large current flows, for example, a conductor between a terminal pad for power supply and an electronic component mounting pad in the figure, and the structure thereof is a thick film outer film 21 such as glass. 21 and a thick conductor film 22 through which a large current flows. The thick film outer shape films 21, 21 are formed, for example, in a frame shape so as to face each other so as to regulate the outer shape of the thick film conductor film 22, and the frame-shaped thick film outer shape films 21, 2 are formed.
The thick film conductor film 22 is arranged in a region surrounded by 1.

The thick film outline films 21 and 21 are formed by printing an insulating glass paste containing borosilicate glass or an organic vehicle by screen printing, drying it, and baking it.

The thick film conductor film 22 is a frame-shaped thick film outer film 2.
In the region surrounded by 1 and 21, for example, Ag-based (A
g simple substance, alloy containing Ag, etc.), Cu-based (Ag simple substance, A
conductive material such as an alloy containing g), an organic vehicle, and a conductive paste having a glass frit as necessary. The above-mentioned Ag-based and Cu-based conductive pastes are filled, dried, and fired to form. To be done.

As the filling method, for example, coating with a dispenser or printing / coating with a screen having a coarse mesh or a metal mask is performed.

The thick film outer film 21, 21 is formed on the thick film conductor film 2.
Since it becomes a dam film that regulates the outer shape of No. 2, it is necessary to control the viscosity by adjusting the organic vehicle in the base to prevent paste sag.

The thick film conductor 3 is a conductor through which a normal current flows, and its structure is formed by printing an Ag-based or Cu-based conductive paste by screen printing, drying it, and then firing it. .

Thereafter, if necessary, a protective film is formed on the thick film conductors 2 and 3, and various electronic components 4 are mounted.

Since the thick film conductors 2 and 3 are adjacent to each other as shown in FIG. 1, when attempting to achieve high-density wiring, even if the distance between the thick film conductor 2 and the thick film conductor 3 is reduced. Since the thick film outer shape films 21 and 21 forming the thick film conductor 2 are made of glass having an insulating property, the short circuit phenomenon does not occur.

A method of manufacturing the above-mentioned thick film circuit board will be described.

First, the ceramic substrate 1 is prepared. For example, it is formed by firing an unfired ceramic body having a predetermined shape.

Next, the thick film conductor 3 is formed. Specifically, the usual thick film method is used to print the conductive paste through a screen on which a predetermined wiring pattern can be formed. As a result, a conductor having a predetermined wiring pattern to be the thick film conductor 3 is printed / applied on the ceramic substrate 1. The conductor is dried to remove the organic solvent contained in the conductor and then subjected to firing treatment. As a result, the conductive powder in the conductor undergoes a firing reaction, is agglomerated with each other, and firmly adheres to the ceramic substrate 1. In addition, in the pattern of the thick film conductor 3, the thick film conductor 3 is also formed in a portion where the thick film conductor 2 is formed in the next step.
May be formed.

Next, the frame-shaped thick film outer shape films 21 and 21 which form the thick film conductor 2 are formed. This thick film outer shape film 21, 21
Is for controlling the boundary of the outer shape of the thick film conductor 2, and is formed along the boundary shape of the outer shape of the thick film conductor 3.
Specifically, the thick film outer shape films 21 and 21 are printed with a borosilicate glass paste on a screen and then dried,
It is formed by baking treatment. In addition, the thick film outline film 2
The thicknesses of 1 and 21 are about 30 to 200 μm, and in order to achieve this, it is necessary to use a paste having a relatively high viscosity.

Next, the thick film conductor film 2 constituting the thick film conductor 2
Form 2. The thick film conductor film 22 substantially allows a large current to flow, and therefore, it is necessary to make the thickness sufficiently thicker than that of the thick film conductor 3. Therefore, the thick-film conductor film 22 is formed by using a region surrounded by the thick-film outer shape films 21 and 21 and filling, drying and firing the conductive paste in the region. Specifically, the conductive paste is injected and supplied by using a dispenser, and then 100 to 150 to remove the organic solvent in the filled conductive paste.
Drying is carried out at ℃, followed by baking treatment. The firing process is
Depending on the material of the conductive paste, for example, when the conductive powder is Ag-based, it is about 850 to 90 in the air atmosphere.
Firing is performed at 0 ° C., and in the case of Cu-based material, firing is performed at about 900 to 950 in a neutral or reducing atmosphere.

In the process up to about 850 ° C. or higher, the organic resin component contained in the dried conductive paste is completely burned out.

The outer shape of the thick film conductor film 22 of the thick film conductor 2 is restricted by the thick film outer shape films 21 and 21. Therefore, the supplied conductive paste does not flow out of the thick film outer shape films 21 and 21, and the thickness of the thick film conductor film 22 can be easily increased.

For example, the thick film outer shape film 21, which has been baked,
When the thickness of 21 is 50 μm and the facing interval is about 2 m, the thickness of the thick conductor film 22 after being supplied and dried is 7
5 μm (can be made thicker than the thick film outer shape film 21 due to surface tension), and the thickness after firing is 50 μm
Can be

As described above, according to the above-described structure and manufacturing method, it is possible to increase the thickness of a specific thick film conductor 2 through which a large current flows among the thick film conductors 2 and 3 very easily. It is possible to easily cope with this large current. In addition, as in the past, widening the thick-film conductor leads to an increase in the size of the board, the printing / drying process due to multiple printing is complicated, and the reliability of the solder coating is reduced. There will be no restrictions on the subsequent manufacturing process and heat treatment process.

Further, in FIG. 1, the thick film outer shape film 21,
A space exposing the surface of the ceramic substrate 1 is formed between the thick film conductor 21 and the thick film conductor 3 adjacent thereto. However, the thick film contour film 21 is superposed on the adjacent thick film conductor 3. It can also be formed, and a higher density of the wiring pattern can be achieved.

In the above-mentioned manufacturing method, as a method for supplying the conductive paste to be the thick conductor film 22, a screen having a coarse mesh may be used for printing / application in addition to the supply by the dispenser.

Next, the third invention will be described. In this embodiment, the thick film outer shape film 21 is formed of a resin material (hereinafter referred to as the thick film outer shape resin film 21), and the region surrounded by the frame-shaped thick film outer shape resin film 21 is filled. When the thick conductive film 22 is formed by firing the above-mentioned conductive paste, the thick outer resin film 21 is burned off.

As described above, the ceramic substrate 1 is prepared and the thick film conductor 3 is formed.

Next, the frame-shaped thick-film outer shape resin films 21, 21 constituting the thick-film conductor 2 are formed. Thick film outline resin film 21,
In No. 21, acrylic-based or epoxy-based resin paste is printed on a screen and then cured.

Next, the thick film conductor film 2 constituting the thick film conductor 2
Form 2. Specifically, using a dispenser,
The area surrounded by the frame-shaped thick film outer shape resin films 21, 21 is filled with a conductive paste, and then 100 to 15
Dry at 0 ° C.

Next, the supplied conductive paste is fired. The firing process varies depending on the material of the conductive paste. For example, when the conductive powder is Ag-based, it is fired at about 850 to 900 ° C. in the air atmosphere, and when it is Cu-based,
Baking is performed at about 900 to 960 ° C. in a neutral or reducing atmosphere.

As a result, the thick-film conductor 2 is achieved, and the resin-made thick-film exterior resin films 21, 21 are burned and removed.

The outer shape of the thick film conductor film 22 of the thick film conductor 2 is regulated by the thick film outer shape resin films 21 and 21. Therefore, the supplied conductive paste is thick resin film 2
It doesn't flow to 1 and 21. Moreover, the thickness of the thick conductor film 22 can be easily increased by supplying the conductive paste, and a large current can be easily accommodated.

Moreover, since the thick-film outer shape resin films 21, 21 are burned out, the thick-film conductor 2 is substantially only the thick-film conductor film 22. Therefore, the thick film external resin films 21 and 21 which are unnecessary for the circuit operation are eliminated, and the appearance is excellent, and the short-circuit phenomenon between the adjacent thick film conductors 3 can be completely suppressed.

Next, a fourth invention will be described with reference to the invention. In the previous embodiment (third invention), the thick film outer shape resin films 21, 21
As a method of removing the thick film conductor film 22, the thick film conductor film 22 is burnt off during the baking process. In this embodiment, the thick film outer shape resin films 21, 21 made of resin are positively added before the thick film conductor film 22 is baked.
Is to be removed.

Specifically, the ceramic substrate 1 is prepared,
The thick film conductor 3 is formed.

Next, the frame-shaped thick film outer shape resin films 21, 21 which constitute the thick film conductor 2 are formed. Thick film outline resin film 21,
In the case of 21, an acrylic, acrylic, or epoxy resin paste contained in the ultraviolet curable material is printed on a screen, and thereafter, a curing treatment is performed by ultraviolet curing or heat curing.

Next, the thick film conductor film 2 constituting the thick film conductor 2
Form 2. Specifically, using a dispenser,
The conductive paste is injected and supplied into a region surrounded by the thick film outer shape resin films 21 and 21, and then 100 to 150
Dry at ℃. As a result, the supplied shape of the supplied conductive paste is maintained by the organic bander.

Next, the thick film outer shape resin films 21 and 21 are removed. Specifically, the thick film outer shape resin films 21 and 21 made of acrylic or epoxy resin are subjected to dissolution treatment using an alkaline solvent such as triethanolamine or a cellosolve solvent.
As a result, only the conductor to be the thick film conductor 3 and the thick film outer shape film 22 is left on the ceramic substrate 1. Note that the solvent and the like remaining on the ceramic substrate 1 are completely burned off by the firing process in the next step, so a strict cleaning step can be omitted.

Next, the conductor to be the thick conductor film 22 is fired. The firing treatment varies depending on the material of the conductive paste. For example, when the conductive powder is Ag-based, it is fired at about 850 to 900 ° C. in the air atmosphere, and when it is Cu-based, a neutral or reducing atmosphere is used. And baking at about 900-950 ° C.

The thick film conductor film 22 of the thick film conductor 2 is regulated at the boundary portion of its outer shape by the thick film outer shape resin films 21, 21. Therefore, the supplied conductive paste does not flow to the thick film outer shape resin films 21, 21. Further, the thickness of the thick conductor film 22 can be easily increased, and the thick conductor film 22 after firing can easily cope with a large current.

Moreover, since the thick film outer shape resin films 21 and 21 are removed, the thick film conductor is substantially the thick film conductor film 2.
Only 2. Therefore, the thick external resin films 21 and 21 which are unnecessary for the circuit operation are eliminated, and the external appearance is excellent.
It is possible to completely suppress the short circuit phenomenon between the adjacent thick film conductors 2.

As described above, according to the present invention, in forming the structure (first invention) for increasing the thickness of the conductor portion through which a large current flows and the conductor, the outer shape of the conductor is first regulated. The manufacturing method (second invention) of forming the thick film outer shape film with a glass material, and the modified modes (third invention, fourth invention) of the manufacturing method.

In each of the above embodiments, a single plate-shaped ceramic substrate is used as the base, but the base may be a multilayer ceramic substrate.

The thick film conductor 3 is directly baked on the fired ceramic substrate 1. However, in the case of a multilayer ceramic substrate, a conductor to be the thick film conductor 3 is formed on an unfired substrate, The thick film conductor 3 and the thick film conductor 3 may be integrally fired.

[0061]

As described above, according to the first aspect of the present invention, a thickness that can easily cope with a large current without increasing the width of the thick film conductor and without causing a short circuit with an adjacent thick film conductor. The thick film circuit board has a film conductor.

Further, according to the second to fourth inventions, since the thick film conductor which can cope with a large current can be formed by utilizing the thick film outer shape film, it is possible to cope with a large current easily and surely. ,
Moreover, it is possible to easily manufacture a thick film conductor that does not cause a short circuit with an adjacent wiring pattern.

[Brief description of drawings]

FIG. 1 is a plan view of a thick film circuit board according to the present invention.

FIG. 2 is a cross-sectional view taken along line XX in FIG.

FIG. 3 is a process drawing for explaining the manufacturing method of the second invention.

FIG. 4 is a process drawing for explaining the manufacturing method of the third invention.

FIG. 5 is a process drawing for explaining the manufacturing method of the fourth invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Thick film conductor 21 ... Thick film external film 22 ... Thick film conductor film 3 ... Thick film conductor

Claims (4)

[Claims] 1. A thick film circuit board formed by forming a thick film conductor having a predetermined wiring pattern on a heat resistant substrate, wherein the thick film conductor is partially filled inside a frame-shaped thick film outline film. A thick film circuit board having a thick film conductor film formed thereon. 2. A step of forming a frame-shaped thick film outline film on a heat-resistant substrate by printing and baking an insulating glass paste, and filling a conductive paste inside the frame-shaped thick film outline film. And a step of forming a thick film conductor film by baking, and a method for manufacturing a thick film circuit board. 3. A step of forming a frame-shaped thick film outline resin film by printing and curing a resin paste on a heat-resistant substrate, and conducting inside the frame-shaped thick film outline resin film. A method for manufacturing a thick film circuit board, comprising: a step of filling a conductive paste to form a conductor to be a thick film conductor by drying; and a step of firing the conductor. 4. A step of forming a frame-shaped thick film outer shape resin film by printing and curing a resin paste on a heat-resistant substrate, and conducting inside the frame-shaped thick film outer shape resin film. Thick film circuit board including a step of forming a conductor to be a conductor film by filling with a conductive paste and drying, a step of dissolving and removing the thick film outer shape resin film, and a step of baking the conductor. Manufacturing method.