JP2002359464A - Method of manufacturing wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing wiring board, which is equipped with wiring and electrodes that are arranged on both its main surfaces and surely connected together via a through-hole, and improved in reliability without making the manufacturing process complicated and increasing the cost. SOLUTION: A film 10 is formed on one main surface (front surface) of a board 1 provided with a through-hole 4, then metal thin films 11 and 11a are each formed inside the through-hole 5 and the other main surface (rear surface) of the board 1, where the film 10 is not formed; and then the film 10 is removed, by which the metal thin film 11a (conduction electrode) of smooth surface is exposed to the other surface (rear surface). Then, a conductor pattern 12 is formed on the front surface of the board 1, and the conductor pattern 12 formed on the front surface of the board and the metal thin film 11 formed on the rear surface of the board 1 are surely made conductive via the metal thin film (conduction electrode) exposed on the surface of the board 1 via the through-hole 4.

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 wiring board, and more particularly, to a method for manufacturing a wiring board, in which wiring and electrodes are provided on both front and back surfaces of a substrate made of a dielectric material and the like. The present invention relates to a method of manufacturing a wiring board having a structure connected to each other through a hole.

[0002]

2. Description of the Related Art In recent years,
For example, as shown in FIG.
1, an electrode 52 is provided on the lower surface, a wiring pattern 53 is provided on the upper surface, and these electrodes 52 and the wiring pattern 53 are connected to a through hole 57 in which a conduction electrode 56 is provided in a through hole 54. 2. Description of the Related Art Wiring boards having a structure in which they are electrically connected to each other via a wire are widely used for various applications.

By the way, a wiring board as shown in FIG.
Usually, it is manufactured by a method as described below. (1) First, as shown in FIG. 3A, a through hole 54 for a through hole is formed in the substrate 51. (2) Next, as shown in FIG. 3B, after filling the metal paste 55 into the through holes 54, baking (sintering) is performed. (3) Then, both main surfaces of the substrate 51 are polished together with the conducting electrodes (sintered body of the metal paste 55) 56 filled and arranged in the through holes 54, as shown in FIG. , Both main surfaces of the substrate 51 are smoothed. As a result, a through hole 57 in which the conduction electrode 56 is filled in the through hole 54 is formed. (4) Then, as shown in FIG. 3D, after forming a metal thin film as an electrode 52 on one main surface (lower surface) of the substrate 51, as shown in FIG. A wiring pattern 53 is formed on the other main surface (upper surface) of the device, and the electrode 52 and the wiring pattern 53 are conducted to each other via a through hole 57. Thereby, a wiring board as shown in FIG. 2 is obtained.

However, in the above-described conventional method for manufacturing a wiring board, the metal paste 55 is required in the step (2).
When baking, the metal paste 55 (the conductive electrode 5
When voids (voids) are generated inside 6) or when the two main surfaces of the substrate 51 are polished together with the conduction electrodes 56 that are filled and disposed in the through holes 54 in the step (3), ,
Since the surface of the conduction electrode 56 is not sufficiently smooth and the surface roughness is rough, the connection resistance between the conduction electrode 56 and a conductor pattern (wiring or electrode) formed thereon is increased, and However, there is a problem that it is difficult to secure high conduction reliability. In addition, there is a problem in that the filling of the through hole with the metal paste and the polishing of both main surfaces of the substrate are troublesome, the number of manufacturing steps is increased, and the cost is increased.

The present invention has been made to solve the above-mentioned problems, and it is possible to form wirings and electrodes provided on both main surfaces of a substrate through through holes without complicating the manufacturing process and increasing the cost. It is an object of the present invention to provide a highly reliable method for manufacturing a wiring board, which can be reliably made conductive through the wiring.

[0006]

In order to achieve the above object, a method of manufacturing a wiring board according to the present invention (claim 1) includes a step of forming a through hole in the board, and a step of forming one of the main surfaces of the board (hereinafter, referred to as a through hole). Disposing a film on the “front surface”), and forming a metal thin film on the inside of the through-hole and on the back surface of the substrate from the other main surface (hereinafter “rear surface”) of the substrate on which the film is not disposed. Forming a film, removing the film from the surface of the substrate to expose a metal thin film formed inside the through-hole to the surface of the substrate, and removing the substrate from the through-hole on the surface of the substrate. Forming a conductive pattern that is electrically connected to the metal thin film formed on the back surface of the substrate via the metal thin film exposed on the front surface of the substrate.

After arranging a film on one main surface (front surface) of a substrate having a through hole formed therein, the inside of the through hole is formed from the other main surface (rear surface) of the substrate on which the film is not provided. After the metal thin film is formed on the back surface of the substrate, the film is removed to expose a metal thin film (electrode for conduction) having a smooth surface to the surface of the substrate from the through hole. Is formed, the conductor pattern formed on the surface of the substrate and the metal thin film formed on the back surface of the substrate are securely connected via the metal thin film (electrode for conduction) exposed on the surface of the substrate from the through hole. , And a highly reliable wiring board can be manufactured. Further, unlike the conventional case, the step of filling the through-hole with the metal paste and the subsequent polishing step are not required, and the film formation on the back surface of the substrate and the formation of the conductive electrode can be simultaneously performed. Thus, the manufacturing process can be simplified and the cost can be reduced. Note that, in the present invention, the relationship between the front surface of the substrate on which the film is disposed and the back surface of the substrate on which the metal thin film is formed is only a relative one. Without limiting, the side on which the film is disposed is the back side,
The surface on which the metal thin film is formed can be regarded as the surface.

[0008] The method for manufacturing a wiring board according to claim 2 is characterized in that:
As the through hole, a through hole having a taper shape such that the diameter of the front surface side of the substrate on which the film is disposed is smaller than the diameter of the back surface side of the substrate, and the cross-sectional shape in the thickness direction of the substrate becomes substantially trapezoidal. Is formed.

The through hole has a tapered shape such that the diameter of the front surface of the substrate on which the film is disposed is smaller than the diameter of the back surface of the substrate, and the cross-sectional shape in the thickness direction of the substrate is substantially trapezoidal. When the holes are formed, when the metal thin film is formed by the thin film forming method from the back surface side of the substrate, there is no discontinuous portion on the inner wall of the through hole and the back surface of the film, and a metal thin film having high conduction reliability is formed. It is possible to form it surely, and it becomes possible to make the present invention more effective.

[0010] In a third aspect of the present invention, a method of manufacturing a wiring board is provided.
As the film, a film soluble in a solvent is used.

By using a film that is soluble in a solvent as the film, the film can be easily removed using the solvent, and the present invention can be made more effective.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described, and features thereof will be described in more detail. FIGS. 1A to 1E are diagrams illustrating a manufacturing process of a wiring board according to an embodiment of the present invention. Hereinafter, a method for manufacturing a wiring board according to an embodiment of the present invention will be described with reference to FIGS.

(1) First, as shown in FIG. 1A, a through hole 4 for a through hole is formed in a dielectric ceramic substrate 1 by a method such as a laser processing method or a sand blast method. In this embodiment, as the through-hole 4,
The diameter of the front surface (upper surface in FIG. 1A) of the substrate 1 is smaller than the diameter of the rear surface (lower surface in FIG. 1A) of the substrate.
Is formed in a tapered shape, the inner peripheral surface of which is inclined so that the cross-sectional shape when the is cut in the thickness direction is substantially trapezoidal. (2) Next, as shown in FIG.
A film 10 (in this embodiment, a dry film resist soluble in a solvent (F-340, manufactured by Fuji Film Ohlin)) is attached. (3) Then, as shown in FIG. 1C, in a state where the film 10 is attached, the through-hole 4 is formed from the back surface (lower surface) side of the substrate 1 on which the film 10 is not provided by the vapor deposition method. A metal thin film (Cu thin film in this embodiment) 11 having a thickness of 3 μm is formed on the inside, the back surface of the film 10 and the lower surface of the substrate 1. At this time, there is no discontinuous portion on the tapered inner peripheral surface of the through hole 4 and the back surface of the film 10,
A metal thin film (electrode for conduction) 11a having high conduction reliability is formed. (4) Next, the substrate 1 is immersed in acetone for 10 minutes, and the film 10 is removed, as shown in FIG. The electrode 11a is exposed on the upper surface of the substrate 1 on which the film 10 is provided. At this time, a metal thin film (electrode for conduction)
The exposed surface of the upper surface 11a of the substrate 1 on which the film 10 is disposed becomes smooth. (5) Thereafter, a conductor pattern (wiring pattern) 12 is formed on the upper surface of the substrate 1 by a lift-off method, and the metal thin film (electrode for conduction) 11 exposed on the upper surface of the substrate 1 from the through hole 4.
The wiring pattern 12 is electrically connected to the metal thin film 11 formed on the lower surface of the substrate 1 via a.

As shown in FIG. 1E, the metal thin film 11 provided on the lower surface of the substrate 1 and the wiring pattern 12 provided on the upper surface of the substrate 1 A) A wiring board having a structure connected to each other via 11a is obtained.

In this embodiment, the through holes 4
When the metal thin films 11 and 11a are formed from the lower surface side of the substrate 1 by a vapor deposition method, the inner wall of the through hole 4 is formed vertically. As compared with the case of (1), the inner wall of the through-hole 4 and the lower surface of the film 10 do not have electrode breakage, so that a highly reliable metal thin film (electrode for conduction) 11a can be reliably formed. Conducting electrode) 11
Since the exposed surface of a is exposed to the upper surface of the substrate 1, the connection resistance between the conductor pattern 12 formed thereon and the metal thin film 11 on the lower surface side of the substrate 1 can be reduced, and A highly reliable wiring board can be manufactured.

Further, unlike the related art, the step of filling the through-hole with the metal paste and the subsequent polishing step are not required, and the film formation on the back surface of the substrate and the formation of the conduction electrode can be performed simultaneously. This makes it possible to simplify the manufacturing process and reduce costs.

In this embodiment, since a dry film resist soluble in a solvent is used as the film, the film can be easily and reliably removed by the solvent (acetone in this embodiment). The manufacturing process can be simplified.

In this embodiment, an example has been described in which a dry film resist (manufactured by Fuji Film Ohlin) soluble in a solvent is used as a film.
The type of film is not limited to this, and various films (for example, an adhesive sheet) can be used.

In the above embodiment, the Cu thin film is formed as the metal thin film (and the conductive electrode). However, the material forming the metal thin film (and the conductive electrode) is not limited to this. It is possible to use various conductive materials.

Further, in the above embodiment, the metal thin film and the conduction electrode on the lower surface side of the substrate are formed by the vapor deposition method.
It is possible to use a thin film forming method such as a VD method or a semi-additive method.

In the above embodiment, the lift-off method is used as a method of forming a conductor pattern (wiring pattern) on the upper surface of the substrate. However, the method of forming the wiring pattern is not limited to the lift-off method, but may be an RIE method. Various methods such as a wet etching method can be used.

The present invention also provides, in yet other respects,
The present invention is not limited to the above embodiment, but relates to the shape and structure of the substrate, the constituent materials thereof, the metal thin film and conductive electrodes formed on the substrate, the specific configuration of the conductor pattern (wiring pattern), and the like. Within the range, various applications and modifications can be made.

[0023]

As described above, according to the method for manufacturing a wiring board of the present invention (claim 1), after a film is provided on one main surface (front surface) of a substrate having a through hole formed therein, the wiring board is formed. After a metal thin film is formed on the inside of the through hole and the back surface of the substrate from the other main surface (back surface) side where the film is not disposed, the film is removed to remove the metal thin film having a smooth surface. The common electrode is exposed from the through-hole to the surface of the substrate, and then the conductor pattern is formed on the surface of the substrate. Therefore, the conductor pattern formed on the surface of the substrate and the metal formed on the back surface of the substrate are formed. The thin film can be reliably conducted through the metal thin film (conduction electrode) exposed from the through hole to the surface of the substrate, and a highly reliable wiring substrate can be manufactured. Further, unlike the conventional case, the step of filling the through-hole with the metal paste and the subsequent polishing step are not required, and the film formation on the back surface of the substrate and the formation of the conductive electrode can be simultaneously performed. Thus, the manufacturing process can be simplified and the cost can be reduced.

According to a second aspect of the present invention, the diameter of the through-hole on the front surface side of the substrate on which the film is provided is smaller than the diameter of the back surface side of the substrate, When forming a through hole having a tapered shape such that the cross-sectional shape is substantially trapezoidal, when forming a metal thin film by a thin film forming method from the back surface side of the substrate,
There is no discontinuous portion on the inner wall of the through hole and on the back surface of the film, and a metal thin film with high conduction reliability can be reliably formed, so that the present invention can be made more effective.

Further, by using a film soluble in a solvent as the film as in the method for manufacturing a wiring board according to the third aspect, the film can be easily removed using the solvent. Can be made more effective.

[Brief description of the drawings]

FIGS. 1A to 1E are diagrams showing main steps of a method for manufacturing a wiring board according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating an example of a configuration of a wiring board.

FIGS. 3A to 3E are diagrams showing main steps of a conventional method for manufacturing a wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 4 Through hole for through hole 10 Film (dry film resist) 11 Metal thin film (Cu thin film) 11a Metal thin film (electrode for conduction) (Cu thin film) 12 Conductor pattern (wiring pattern)

Claims (3)

[Claims] A step of forming a through hole in the substrate; a step of disposing a film on one principal surface (hereinafter referred to as “front surface”) of the substrate; and a step of disposing a film of the substrate on which the film is not disposed. Forming a metal thin film on the inside of the through hole and on the back surface of the substrate from the main surface (hereinafter, “back surface”) side; and removing the film from the surface of the substrate to form a metal thin film inside the through hole. Exposing the metal thin film on the surface of the substrate; and, on the surface of the substrate, a conductive pattern that is electrically connected to the metal thin film formed on the back surface of the substrate via the metal thin film exposed from the through hole to the surface of the substrate. Forming a wiring board. 2. A taper in which the diameter of the front surface of the substrate on which the film is provided is smaller than the diameter of the rear surface of the substrate, and the cross-sectional shape in the thickness direction of the substrate is substantially trapezoidal. 2. The method for manufacturing a wiring board according to claim 1, wherein a through hole having a shape is formed. 3. The method according to claim 1, wherein a film soluble in a solvent is used as the film.