JPH11330691A - Manufacture of conductor circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a conductor circuit which can cope with formation of a fine conductor pattern and simplify a manufacturing process. SOLUTION: On a substrate in which a conductor circuit is formed, an overcoat layer is formed except a part to be exposed, a protective film is formed on the overcoat layer and the part to be exposed, a hole for a through hole is bored and adsorption of catalyst or formation of a conductive layer on the inner wall of the through hole is performed. The protective film is eliminated, and a conductive film is formed on the through hole inner wall by a plating method. Thus, electric connection is performed.

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 conductor circuit having through holes in a conductor circuit which is increasingly miniaturized, speeded up, increased in density and reduced in power consumption. It relates to a conductor circuit. For example, the present invention is extremely useful as a method for producing a conductor circuit such as a planar coil for a magnetic head of a magnetic recording device, in addition to a precision wiring board such as a planar coil for a motor or an actuator, and an interposer (different pitch connecting parts).

[0002]

2. Description of the Related Art In recent years, in order to reduce the size of a conductor circuit such as a printed circuit board, the dimensions of through holes and through hole lands for making electrical connections between multiple layers have been reduced, and the size of a conductive pattern has been reduced. Was desired. Generally, in a circuit board having a conductor pattern,
The following method is used to establish electrical connection between the multilayers through the through-hole because there is no conduction line connected to the through-hole. In a circuit board in which a hole for a through hole is formed, a step of adsorbing and forming a catalyst layer for electroless plating on the inner wall of the through hole and the entire surface of the substrate; Forming a conductor layer by plating,
A step of masking the conductor pattern portion excluding the through-hole portion using a photoresist photolithography, an electrolytic plating step of an inner wall of the through-hole, a step of removing the masking material, a step of quick-etching the conductor layer formed on the substrate surface, Further, a method of sequentially performing a step of forming an overcoat layer in a portion other than a portion to be exposed on the substrate surface is generally used.

[0003]

However, in the conventional method, a conductor layer is formed on the entire surface of the substrate by electroless plating, thereafter, only the inner wall of the through hole is electrolytically plated, and an excess conductor layer on the surface of the substrate is removed by etching. Therefore, there is a problem that it is not suitable as a method for forming a circuit board having a fine pattern. Further, conventionally, it is necessary to remove unnecessary conductors other than the through-hole portion, and a protective film is formed in the through-hole portion, and then the unnecessary conductor is removed by etching, so that the process is complicated.

Accordingly, the present invention improves the electrical connection reliability by forming a conductive film on the inner wall of the through-hole by plating, and at the same time, forms a conductive circuit for each layer, thereby forming a conductive circuit for plating connected to the through-hole land. A method of manufacturing a conductor circuit having a through hole by forming a wire, forming a catalyst or a conductive layer only on a through hole portion using a protective layer, and performing plating only on at least the through hole portion and the conductor pattern portion. Is provided.

That is, since the present invention does not require a step of forming a conductor layer on the entire surface of the substrate, a step of removing an unnecessary conductor layer after plating the through-hole portion is unnecessary, and a photo for removing the unnecessary conductor is eliminated. Since the step of forming a protective film by lithography can be omitted, the manufacturing process can be simplified.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have formed a conductive line for plating connected to a through-hole land in a step of forming a conductive circuit of each layer, and formed a catalyst or a catalyst. By forming the conductive layer only on the through-hole portion using the protective film, and performing plating only on at least the through-hole portion and the conductor pattern portion,
It has been found that a conductor circuit having a fine pattern can be formed, and the present invention has been completed.

That is, in the first invention, an overcoat layer is formed on a substrate on which a conductive circuit is formed, except for an exposed portion, and a protective film is formed on the overcoat layer and the exposed portion. Then drill holes for through holes,
After adsorbing a catalyst or forming a conductive layer on the inner wall of the through hole, the protective film is removed, and a conductive film is formed on the inner wall of the through hole by a plating method to perform electrical connection. This is a method for manufacturing a conductor circuit.

With such a configuration, a conductor circuit having a fine pattern can be easily manufactured, and the process can be simplified. According to a second invention, a protective film is formed on the entire surface of the substrate on which the conductor circuit is formed, and a hole for a through hole is formed.
After adsorbing a catalyst or forming a conductive layer on the inner wall of the through hole, the protective film is removed, and then an overcoat layer is formed on a portion other than a portion to be exposed, and then a conductive film is formed on the inner wall of the through hole by a plating method. And a method of manufacturing a conductor circuit, wherein electrical connection is made by forming a conductive circuit.

With this configuration, a conductor circuit having a fine pattern can be easily manufactured, and the process can be simplified. According to a third aspect of the present invention, a protective film is formed on the entire surface of the substrate on which the conductive circuit is formed, a hole for a through hole is formed, and after the catalyst is adsorbed or a conductive layer is formed on the inner wall of the through hole, After removing the protective film, a conductive film is formed on the inner wall of the through-hole by a plating method to perform electrical connection, and then the unnecessary conductive film other than the inner wall of the through-hole is removed by polishing the substrate surface. A method of manufacturing a conductor circuit, comprising forming an overcoat layer on a portion other than a portion to be exposed thereafter.

With this configuration, a conductor circuit having a fine pattern can be easily manufactured, and the process can be simplified.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a conductor circuit according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing the process, and shows a through-hole portion for simplification. FIG. 2 shows an example of a plane pattern of a conductor circuit. It is not limited to this example. FIG. 3 shows a method for manufacturing a conductor circuit according to the third invention of the present invention.

First, a photosensitive resin composition is applied on a conductive substrate, and is exposed to energy rays such as a mercury lamp through a photomask or the like. Then, an unexposed portion of the photosensitive resin composition is developed with a developer. After dissolving or dispersing to form a desired resin pattern on the conductive substrate, a conductor is formed by electrolytic plating. Next, after the electroplating, the insulating material 3 is adhered to the surface of the conductor pattern opposite to the conductive substrate,
Alternatively, the conductive substrate is removed after a plurality of conductor patterns are stacked with an insulating material interposed therebetween.

As a method of removing the conductive substrate, for example, a method of etching with an aqueous solution of an acid, an alkali, or a salt;
A method such as a method of polishing and shaving, a method of mechanical peeling, or a combination thereof can be used. If necessary, the resin image portion may be removed before transferring the conductive pattern to the insulating substrate or after transferring and removing the conductive substrate.

Although there is no particular limitation on the insulating material 3 used in the transfer, epoxy-based adhesive resin, acrylic-based adhesive resin, polyimide-based adhesive resin, maleimide-based adhesive resin,
Usual adhesive resins such as styrene adhesive resin and polyester adhesive resin can be used. The formed insulating material layer functions as an electrical insulating layer between the layers forming the multilayer circuit board. When the resin image portion is removed before the transfer, the insulating material also functions as an electrical insulating resin between the conductor patterns in the same layer. In order to reinforce the circuit board, a film such as a polyimide film or an aramid film, a glass cloth, or the like may be included in the layer of the insulating material 3.

Next, as shown in FIGS. 1 (a) to 1 (c), the conductive circuit is obtained by removing the conductive substrate and bonding the first layer circuit 4 and the second layer circuit 5 via the insulating material 3. An overcoat layer 8 is formed thereon, and a protective layer 7 is formed thereon. Next, a hole is formed in the through hole land 1 by a laser to adsorb a catalyst on the inner wall of the through hole, or after forming a conductive layer, a conductive film 6 is formed by electrolytic plating.

When a resin pattern is formed inside the through hole land 1, the resin pattern can be removed by irradiating a high energy beam such as a laser beam, a drill method, or a punch method. Further, even when there is no resin pattern inside the through hole land 1, a through hole can be formed by a normal drilling method or a punching method. The inner diameter of the through hole is preferably from 10 to 250 μm. When the inner diameter of the through hole is smaller than 10 μm, it is difficult to secure connection reliability by the through hole between the multilayers.
When the size exceeds 50 μm, there is a problem that the size of the conductor circuit becomes large.

Although there is no particular limitation on the overcoat layer, ordinary solder resists, plastic films having high heat and chemical resistance, and photoresists can be used. The protective film is not particularly limited, but a protective film that can be peeled off later, for example, a plastic film with an adhesive,
A photoresist can be used. Examples of the plastic film include, but are not limited to, polyethylene, polypropylene, polyester, aromatic polyether, aromatic polyester, and aromatic polyimide. As the photoresist, a normal photosensitive resin that can be removed later, such as a liquid photosensitive resin or a dry film resist, can be used.

It is preferable that the protective film is formed before drilling the through-hole land. When a photoresist is used, it is possible to form a resist pattern covering portions other than the through-holes after the through-hole drilling step, but the number of manufacturing steps increases because patterning is performed using photolithography. In addition, when the diameter of the through hole is reduced, it is necessary to align the exposure mask and the circuit board without displacement, and high alignment accuracy is required.

Further, in the present invention, after electrical conduction of the through-holes is established, the electrical connection between the through-holes is further increased through an insulating material.
By bonding two or more layers and forming a through hole in a similar manner, a multilayer conductor circuit can be manufactured. The method for electrically connecting a through hole according to the present invention is a method of forming a conductive film on the inner wall of the through hole by plating. Conducting by electroplating by applying a conductive compound to the inner wall in the through hole, electroplating, forming a catalyst layer on the surface by adsorption, forming a thin electroless plating film, and then electroplating A method for forming a film is used. In addition, when the diameter of the through hole is reduced, hydrogen generated by the electroless plating method is difficult to escape, so that a method in which a conductive compound is applied to the inner wall in the through hole and the electrolytic plating is performed than the method using the electroless plating is not used. preferable.

As shown in FIG. 2, in the present invention, after a conductor film is formed on the inner wall of the through hole by plating,
By cutting the electroplating conductive line 12 by the cutting line 14, the coil-shaped conductor circuit 11 can be electrically separated from the production substrate. The method of cutting the conductive wire is not particularly limited, but a cutting tool such as a drill, a mold, and a cutter can be used. The width of the conductive line is not particularly limited, but is preferably in the range of 20 to 200 μm. By cutting the conductive wire 12 for plating, the electrical inspection can be performed without separating the conductor circuit from the substrate, so that the time required for the inspection can be greatly reduced. The method of separating the conductor circuit from the production substrate is not particularly limited, but a method of punching out with a die or a method of linearly removing the resin pattern around the circuit by irradiating a high energy beam such as a laser can be used.

As shown in FIGS. 3A to 3E,
First circuit 4 having conductor pattern 2 on both sides of insulating material 3
After forming the protective film 7 on the substrate on which the second circuit 5 is formed, a hole is formed in the through hole land 1. After that, a catalyst or conductive layer is formed only in the through hole part,
After removing the protective film 7, the conductor film 6 is formed on the inner wall of the through hole and the surface of the substrate by plating, and then the overcoat layer 8 is formed.

Since the conductor film is formed on the conductor pattern, unnecessary conductors are removed by polishing the surface. There is no particular limitation on the polishing method, but buffing, rubber,
A method using a polishing plate or a roll-shaped abrasive made of a ceramic material, or a method such as a sandblaster method in which fine particles of sand, metal, ceramics, or the like collide with the substrate surface can be used.

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited by the embodiments.

[0024]

Example 1 An alkali-developing liquid photosensitive resin was cured on a photomask having a coil-shaped pattern with a coil size of 2 mm in diameter and a pitch of 30 μm through a PET film of 10 μm in thickness. It was applied so as to have a thickness of 60 μm, and an aluminum substrate was laminated thereon. Exposure was performed using parallel light from a mercury short arc lamp, and development was performed with a 1% aqueous sodium borate solution.

Next, strike plating is performed at a current density of 3 A / dm 2 for 6 minutes using a copper pyrophosphate plating solution manufactured by Uemura Kogyo Co., Ltd.
A conductive pattern of 0 μm was formed. A through-hole land portion composed of a conductor pattern having an outer diameter of 160 μm and a resin pattern having an outer shape of 100 μm at the center thereof, and a width of 50 μm
The conductive wire for electrolytic plating of the through hole of m was simultaneously produced in the coil-shaped pattern forming step.

The two-layer circuit composed of the conductor and the resin pattern prepared as described above was laminated via a 25 μm-thick polyimide film using a WA-modified acrylic adhesive manufactured by DuPont, and the aluminum substrate was removed by etching with hydrochloric acid. . After that, a solder resist pattern is formed on the circuit pattern portion other than the terminal portion exposed on the surface, and then a 30 μm thick dry film resist is laminated as a protective film on both front and back surfaces of the substrate, and is exposed to light from a mercury short arc lamp. did. A 100 μm diameter resin pattern at the center of the through hole land located at the center of the coil was removed by irradiating a carbon dioxide gas laser beam, and a through hole was formed by penetrating. The removal of the resin pattern by the carbon dioxide gas laser was easily performed without strict adjustment of the diameter and output of the laser beam, with the conductor pattern disposed outside serving as a light-shielding mask.

Laser drilling is performed by Mitsubishi Electric ML50
The test was performed using a 5GT carbon dioxide laser processing machine. The output of the laser beam was 300 W, the pulse width was 50 μs, and the beam diameter was 60 μm. A through hole having an outer diameter of 100 μm and an aspect ratio of 2 was produced. Further, after treating the inner wall of the through hole with a direct plating solution manufactured by Okuno Pharmaceutical Co., Ltd., the protective film on the surface is removed, and a copper film having a thickness of 20 μm is formed by copper sulfate plating to electrically connect the two layers. A connected small planar coil was fabricated. The conductive wire used for electrolytic plating was removed by drilling, and the planar coil was electrically separated from the substrate. Furthermore, the resin pattern around the planar coil was cut off from the substrate by irradiating a carbon dioxide laser beam and removing the resin pattern linearly with a width of 50 μm. The resistance value of the through hole was less than 0.2Ω, and no change was observed in the resistance value in the heating test at 230 ° C. for 3 minutes.

[0028]

Example 2 A conductor / resin pattern was prepared in the same manner as in Example 1 except for the method of electrically connecting through holes. DuPont WA made of two layers consisting of conductor and resin pattern
The laminate was laminated via a 25 μm-thick aramid film using a modified acrylic adhesive, and the aluminum substrate was removed by etching with hydrochloric acid. Thereafter, a solder resist pattern is formed on a circuit pattern portion other than the terminal portion (exposed portion) exposed on the surface, and then a 30 μm-thick dry film resist is laminated as a protective film on both front and back surfaces of the substrate, and a mercury short arc lamp is formed. Exposure. The diameter is 1 at the center of the through hole land located at the center of the coil.
A 00 μm through hole was formed using a drill.

The method of electrically connecting the through holes was carried out as follows. A palladium layer as a catalyst was formed by treating the inner wall of the through hole with a hydrochloric acid solution of stannous chloride and a hydrochloric acid solution of palladium chloride in this order. Next, the protective film formed on the substrate surface was peeled off. Thereafter, the film was immersed in an electroless copper plating solution manufactured by Uemura Kogyo Co., Ltd. while shaking at 55 ° C. for 30 minutes to form a copper film having a thickness of several μm. Further, a copper film having a thickness of 20 μm was formed on the inner wall in the through hole by plating with copper sulfate. The cutting of the conductive wire and the separation of the planar coil from the substrate were performed in the same manner as in Example 1. The resistance value of the through hole was less than 0.2Ω, and no change was observed in the resistance value in the heating test at 230 ° C. for 3 minutes.

[0030]

Example 3 An alkali-developing liquid photosensitive resin was cured on a photomask having a coil pattern having a coil size of 2 mm in diameter and a pitch of 30 μm via a PET film having a thickness of 10 μm. It was applied so as to have a thickness of 60 μm, and an aluminum substrate was laminated thereon. Exposure was performed using parallel light from a mercury short arc lamp, and development was performed with a 1% aqueous sodium borate solution.

Next, strike plating is performed at a current density of 3 A / dm 2 for 6 minutes using a copper pyrophosphate plating solution manufactured by Uemura Kogyo Co., Ltd.
A conductive pattern of 0 μm was formed. A through-hole land portion composed of a conductor pattern having an outer diameter of 160 μm and a resin pattern having an outer shape of 100 μm at the center thereof, and a width of 50 μm
The conductive wire for electrolytic plating of the through hole of m was simultaneously produced in the coil-shaped pattern forming step.

The two-layer circuit composed of the conductor and resin pattern prepared as described above was laminated via a 25 μm-thick polyimide film using a WA-modified acrylic adhesive manufactured by DuPont, and the aluminum substrate was removed by etching with hydrochloric acid. . Then, a 30 μm thick protective film is applied on both sides of the substrate.
m of dry film resist was laminated and exposed to light from a mercury short arc lamp. A 100-μm-diameter resin pattern at the center of the through-hole land located at the center of the coil was removed by irradiating a carbon dioxide laser beam to form a through-hole. The removal of the resin pattern by the carbon dioxide gas laser was easily performed without strict adjustment of the diameter and output of the laser beam, with the conductor pattern disposed outside serving as a light-shielding mask. Laser drilling was performed using a Mitsubishi Electric ML505GT carbon dioxide laser processing machine. Laser light output is 300
W, the pulse width was 50 μs, and the beam diameter was 60 μm. A through hole having an outer diameter of 100 μm and an aspect ratio of 2 was produced.

Further, after treating the inner wall of the through hole with a direct plating solution manufactured by Okuno Pharmaceutical Co., Ltd., the protective film on the surface is removed and a solder resist pattern is formed on the circuit pattern portion other than the terminal portion exposed on the surface. Thereafter, a copper film having a thickness of 20 μm was formed by copper sulfate plating to produce a small-sized planar coil electrically connected between the two layers. The conductive wire used for electrolytic plating was removed by drilling, and the planar coil was electrically separated from the substrate. Furthermore, the resin pattern around the planar coil was cut off from the substrate by irradiating a carbon dioxide laser beam and removing the resin pattern linearly with a width of 50 μm. The resistance value of the through hole was less than 0.2Ω, and no change was observed in the resistance value in the heating test at 230 ° C. for 3 minutes.

[0034]

Example 4 An alkali-developing liquid photosensitive resin was cured on a photomask having a coil-shaped pattern having a coil size of 2 mm in diameter and a pitch of 30 μm via a PET film having a thickness of 10 μm. It was applied so as to have a thickness of 60 μm, and an aluminum substrate was laminated thereon. Exposure was performed using parallel light from a mercury short arc lamp, and development was performed with a 1% aqueous sodium borate solution.

Next, strike plating is performed for 6 minutes at a current density of 3 A / dm 2 using a copper pyrophosphate plating solution manufactured by Uemura Kogyo Co., Ltd.
A conductive pattern of 0 μm was formed. A through-hole land portion composed of a conductor pattern having an outer diameter of 160 μm and a resin pattern having an outer shape of 100 μm at the center thereof, and a width of 50 μm
The conductive wire for electrolytic plating of the through hole of m was simultaneously produced in the coil-shaped pattern forming step.

The two-layer circuit composed of the conductor and resin pattern prepared as described above was laminated via a 25 μm-thick polyimide film using a WA-modified acrylic adhesive manufactured by DuPont, and the aluminum substrate was removed by etching with hydrochloric acid. . A 100 μm diameter resin pattern at the center of the through hole land located at the center of the coil was removed by irradiating a carbon dioxide gas laser beam, and a through hole was formed by penetrating. The removal of the resin pattern by the carbon dioxide gas laser was easily performed without strict adjustment of the diameter and output of the laser beam, with the conductor pattern disposed outside serving as a light-shielding mask. Laser drilling made by Mitsubishi Electric
The test was performed using a ML505GT carbon dioxide laser processing machine.
The output of the laser beam was 300 W, the pulse width was 50 μs, and the beam diameter was 60 μm. A through hole having an outer diameter of 100 μm and an aspect ratio of 2 was produced.

Further, after treating the inner wall of the through hole with a direct plating solution manufactured by Okuno Pharmaceutical Co., Ltd., a copper film having a thickness of 20 μm is formed by copper sulfate plating.
A small planar coil in which the layers were electrically connected was manufactured.
Since the conductor layer was entirely covered on the substrate surface, unnecessary conductor portions were removed by polishing. Polishing was performed using a ceramic roll manufactured by Ishii Notation Co., Ltd. A solder resist pattern manufactured by Asahi Chemical Laboratory Co., Ltd. was formed on the circuit pattern portion other than the terminal portion (site to be exposed) exposed on the surface.
The conductive wire having a width of 100 μm used for electrolytic plating was removed by drilling, and the planar coil was electrically separated from the substrate. Furthermore, the resin pattern around the planar coil was cut off from the substrate by irradiating a carbon dioxide laser beam and removing the resin pattern linearly with a width of 50 μm. The resistance value of the through hole was less than 0.2Ω, and no change was observed in the resistance value in the heating test at 230 ° C. for 3 minutes.

[0038]

According to the present invention, a conductive line connected to a through-hole land can be formed in a step of forming a conductive circuit pattern. Therefore, it is not necessary to uniformly form a conductive layer on the entire substrate by electroless plating. The process for removing unnecessary conductors can be simplified, and since there is no etching process in the unnecessary conductor removing process, it is possible to cope with the formation of a conductor circuit having a fine conductor pattern.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a manufacturing process according to a first invention of the present invention.

FIG. 2 is a plan view of a conductor circuit according to the present invention.

FIG. 3 is an explanatory view of a manufacturing process according to a third invention of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inside of a through hole land 2 Conductor pattern 3 Insulating material 4 First layer circuit 5 Second layer circuit 6 Conductive film on inner wall of through hole 7 Protective film 8 Overcoat layer 10 Through hole 11 Coiled conductor circuit 12 Conduction for plating Line 13 Resin pattern 14 Separation line

Claims (3)

[Claims] An overcoat layer is formed on a substrate on which a conductive circuit is formed, except for an exposed portion, a protective film is formed on the overcoat layer and the exposed portion, and then a through-hole is formed. After forming a hole, adsorbing a catalyst or forming a conductive layer on the inner wall of the through hole, removing the protective film, forming a conductive film on the inner wall of the through hole by a plating method, and performing electrical connection. A method for manufacturing a conductor circuit, comprising: 2. After forming a protective film on the entire surface of the substrate on which the conductive circuit is formed, making a hole for a through hole, and adsorbing a catalyst or forming a conductive layer on the inner wall of the through hole.
A method for manufacturing a conductive circuit, comprising: removing the protective film, forming an overcoat layer other than a portion to be exposed, and then forming a conductive film on the inner wall of the through hole by a plating method to perform electrical connection. . 3. A protective film is formed on the entire surface of the substrate on which the conductive circuit is formed, a hole for a through hole is formed, a catalyst is adsorbed on the inner wall of the through hole, or a conductive layer is formed.
After removing the protective film, and then forming a conductive film on the inner wall of the through hole by a plating method to make an electrical connection,
A method for manufacturing a conductive circuit, comprising: removing unnecessary conductive films other than the inner walls of through holes by polishing the surface of the substrate; and forming an overcoat layer on a portion other than a portion to be exposed thereafter.