JPH1117310A - Manufacture of printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the opening position errors of holes caused by the elongation/ contraction of materials in laser processing without requiring any image film by sequentially forming conductive layers and resist layers on both surfaces of an electric insulating plate and forming the holes with a laser processing, and then, removing the resist layers after circuits are formed by removing conductive parts in unnecessary sections. SOLUTION: After conductive layers 2 and resist layers are sequentially formed on both surfaces of an electric insulating plate 1, holes are formed to one of the conductive layers 2 through the insulating plate 1 with a laser beam in accordance with the design patterns of circuits. At this point, the laser beam projecting positions are corrected in conformity wit the expansion/contraction of the plate 1 and layer 2. After the parts of the layers 2 which are not protected with the resist layers are removed and circuits are formed on both surfaces of the plate 1, the resist layers are removed. In addition, groove holes 5 are formed to the conductive layer 2 on the opposite side through the parts of the insulating plate 1 corresponding to circuit connecting spots on both surfaces of the plate 1 with the laser processing and the surfaces of the layers 2 and holes 5 are plated with a conductive metal 6, and then the circuits formed on both surfaces of the plate 1 are electrically connected to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a printed circuit board.

[0002]

2. Description of the Related Art A printed circuit board is known in which circuits are formed on both sides of an electric insulating plate, and the circuits on both sides are electrically contacted at important points. Conventionally, such a printed circuit board is manufactured by the following steps. First, copper foil is adhered to both sides of an electric insulating plate, a photosensitive resist layer for pattern formation is provided on the surface thereof, and an image film having holes formed thereon in accordance with a circuit pattern is placed on the surface. Next, the photosensitive resist layer corresponding to the holes of the image film is exposed by irradiating ultraviolet rays from the outer surface of the image film, and then subjected to a developing treatment to remove the unexposed portions of the photosensitive resist layer.

[0003] Next, portions of the copper foil that are not protected by the photosensitive resist layer are removed with an etchant to form circuits on both sides of the electrical insulating plate. Further, after the photosensitive resist layer is peeled off, a groove extending from the surface of the electrical insulating plate to the copper foil on the opposite side is formed by laser processing at a place where the circuits on both sides are conducted. Next, copper plating is applied to the surfaces of the copper foil and the slots, so that the circuits on both surfaces of the electric insulating plate are conducted.

In the above-mentioned conventional method, an image film having holes formed in accordance with a circuit pattern is required. In general, an image film in which a thick transparent film is coated with an emulsion is used. However, since such an image film easily expands and contracts, especially in the case of a large-sized printed circuit board, an error is likely to occur in a circuit pattern due to a difference in expansion and contraction ratio with other materials. For this reason, it takes time and effort to manage and inspect the image film, and the work of layering the image film must be performed manually and visually, with the utmost care. I have to pull it out.

Further, even after the image films are stacked, complicated steps such as exposure and development of the photosensitive resist layer are required. In addition, when a dry film is used as the photosensitive resist, the film thickness is relatively large, so that a shift is likely to occur at the time of exposure. When a liquid resist is used, pinholes due to uneven coating are likely to occur.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a printed circuit board which has high accuracy, is simple in process, requires no trouble in parts management, and is inexpensive.

[0007]

According to a method of manufacturing a printed circuit board of the present invention, a conductive layer is formed on a surface of an electric insulating plate, a resist layer is formed on the surface, and A hole reaching the conductive layer in the resist layer is formed by laser processing in accordance with a circuit design pattern,
Next, an unnecessary portion of the conductive layer corresponding to the hole is removed with an etchant to form a circuit, and then the resist layer is removed. By forming a hole in the resist layer directly by laser processing, an image film is not required, and labor for attaching the image film and exposing and developing the photosensitive resist layer can be omitted. By correcting the position during laser processing,
Prevents errors in the drilling position due to expansion and contraction of the material.

A conductive layer is formed on both sides of an electric insulating plate, a resist layer is formed on the surface thereof, and a hole reaching the conductive layer is formed in the resist layer by laser processing in accordance with a circuit design pattern. Then, an unnecessary portion of the conductive layer corresponding to the hole is removed with an etchant to form a circuit, and further, after removing the resist layer, a slot reaching the conductive layer on the opposite side of the electric insulating plate is formed. It is also possible to form by laser processing and then to perform plating on the surfaces of the conductive layer and the slots to conduct the circuits on both sides.

[0009]

1 to 6 show a manufacturing process of a printed circuit board. To manufacture a printed board, first, as shown in FIG. 1, a conductive layer 2 made of copper foil is formed on the surface of an electric insulating plate 1 serving as a base, and a resist layer 3 is formed on the surface. The electric insulating plate 1 is appropriately selected from a material obtained by impregnating glass, synthetic fiber, or the like with a polyimide resin, an epoxy resin, or the like, a composite material, or the like, according to the use of the printed circuit board, the required accuracy, and the like. The resist layer 3 is made of a synthetic resin having chemical resistance, and may be a synthetic resin film or a peelable ink.

Next, as shown in FIG. 2, holes 4 reaching the conductive layer 2 are formed in the resist layer 3 by laser processing according to the circuit design pattern. The holes 4 are formed corresponding to unnecessary portions of the conductive layer 2. At this time, the laser processing position is corrected according to the expansion and contraction of the electric insulating plate 1 and the conductive layer 2.

Next, as shown in FIG. 3, portions of the conductive layer 2 which are not protected by the resist layer 3 are removed with an etchant such as ferric chloride to form circuits on both surfaces of the electric insulating plate 1. Then, as shown in FIG. 4, the remaining resist layer 3 is removed. Further, as shown in FIG. 5, a slot 5 extending from the surface of the electric insulating plate 1 to the conductive layer 2 on the opposite side is formed in a portion corresponding to a connection portion of the circuit on both surfaces by laser processing.

Next, as shown in FIG. 6, a conductive metal 6 such as copper is plated on the surface of the conductive layer 2 and the slot 5 with a thickness of about 20 to 30 μm, and the circuit on both surfaces of the electric insulating plate 1 is formed. Conduct.
At this time, a plating resist is printed in advance on portions that are not plated so as not to break the circuit formed by the conductive layer 2. that's all,
I explained about a printed circuit board with circuits on both sides,
It may be a single-sided substrate. In this case, it is not necessary to form the conductive slot 5 in the electrical insulating plate 1.

[0013]

According to the present invention, since a hole is formed directly in the photosensitive resist layer by laser processing, an image film is not required, and therefore, management and inspection of an easily stretchable image film is not troublesome. It is possible to omit complicated steps such as attaching an image film and exposing and developing a photosensitive resist. In addition, processing errors due to expansion and contraction of the image film, processing errors due to misregistration during exposure of the photosensitive resist, and defects due to uneven application of the photosensitive resist can be prevented. Since the position of the hole can be corrected according to the expansion and contraction of the layer, the accuracy is extremely high.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first step of a method for manufacturing a printed circuit board according to the present invention.

FIG. 2 is a sectional view showing a second step of the method for manufacturing a printed circuit board according to the present invention;

FIG. 3 is a sectional view showing a third step of the method for manufacturing a printed circuit board according to the present invention.

FIG. 4 is a sectional view showing a fourth step of the method for manufacturing a printed circuit board according to the present invention.

FIG. 5 is a sectional view showing a fifth step of the method for manufacturing a printed circuit board according to the present invention.

FIG. 6 is a sectional view showing a sixth step of the method for manufacturing a printed board according to the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrical insulating plate 2 Conductive layer 3 Resist layer 4 Hole 5 Slot 6 Conductive metal

Claims (2)

[Claims] 1. A conductive layer is formed on a surface of an electric insulating plate, a resist layer is formed on the surface, and then holes formed in the resist layer reaching the conductive layer are formed by laser processing in accordance with a circuit design pattern. Forming a circuit, removing an unnecessary portion of the conductive layer corresponding to the hole with an etchant to form a circuit, and then removing the resist layer. 2. A conductive layer is formed on both sides of an electric insulating plate, a resist layer is formed on the surface thereof, and a hole reaching the conductive layer is formed in the resist layer by laser processing in accordance with a circuit design pattern. Forming, and then removing unnecessary portions of the conductive layer corresponding to the holes with an etchant to form a circuit,
Further, after removing the resist layer, a slot reaching the conductive layer on the opposite side is formed in the electric insulating plate by laser processing, and then the surface of the conductive layer and the slot is plated to form a circuit on both sides. The method for manufacturing a printed circuit board according to claim 1, wherein