JP2881515B2 - Printed circuit board manufacturing method - Google Patents

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 printed circuit board, and more particularly to a method for manufacturing a printed circuit board suitable for directly drilling a printed circuit board with a carbon dioxide laser.

[0002]

2. Description of the Related Art When a printed circuit board is irradiated with laser light oscillated by a carbon dioxide laser, the laser light is reflected by a copper foil on the surface of the printed circuit board and cannot be processed. For this reason, when drilling a printed circuit board with a laser, the laser beam is irradiated after removing the copper foil at the drilled position by etching or drilling in advance.

[0003]

As described above, in the manufacturing method for previously removing the copper foil at the laser irradiation position, the printed circuit board is positioned and processed using the same reference hole formed in the printed circuit board. Even so, there is a shift between the hole formed in the copper foil and the laser irradiation position due to the precision and the habit of each machine.

When the diameter of the hole formed in the printed circuit board is large, even if the hole formed in the copper foil and the laser irradiation position are slightly shifted, it does not affect the characteristics of the printed circuit board. When the diameter becomes a small hole having a diameter of 0.1 mm to 0.3 mm, the hole formed in the substrate is deformed, and the characteristics of the printed circuit board are adversely affected, such as insufficient connection between the interior and the exterior.

An object of the present invention is to provide a method of manufacturing a printed circuit board in which a copper foil and a substrate are perforated only by laser processing in view of the above circumstances.

[0006]

In order to achieve the above-mentioned object, in the present invention, a plating layer having many irregularities is formed on the surface of a printed circuit board, and the surface is further covered with a synthetic resin.

[0007]

[Action] Then, it improves the energy absorption efficiency of the irradiated laser beam, by melting the concave convex part of the plating layer, the plating layer and to promote the melting of the copper foil, to allow drilling by laser did.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, as shown in FIGS. 1 and 2, the thickness of the synthetic resin substrate 1 is reduced from several μm to 7 μm.
A plating layer 3 having a thickness of several μm to 10 μm and having many irregularities is formed on the surface of a printed board P on which a copper foil 2 of μm is stuck.

Next, as shown in FIG. 3, a coating layer 4 is formed on the surface of the plating layer 3 by applying, for example, a varnish, epoxy-based or rubber-based synthetic resin.

Then, as shown in FIG. 4, a laser beam 5 oscillated from a carbon dioxide gas laser is irradiated to penetrate one of the coating layer 4, the plating layer 3, the copper foil 2 and the substrate 1, and the other copper foil. A hole 6 reaching 2 is formed.

In this way, when the required drilling is completed,
As shown in FIG. 5, cleaning is performed to remove the residue in the hole 6 and the coating layer 4.

Next, as shown in FIG. 6, a plating layer 7 is formed on the surface of the plating layer 3 and in the hole 6, and the copper foils 2 bonded on both sides of the substrate 1 are electrically connected.

Then, as shown in FIG. 7, after etching to form a circuit pattern 8, a resist film 9 is formed as shown in FIG.

As described above, when the copper foil 2 and the substrate 1 are simultaneously processed by the laser beam, there is no concern about a positional shift which would otherwise occur when the copper foil 2 and the substrate 1 are processed in separate processes, and a small-diameter hole can be reliably formed. .

[0015]

As described above, according to the present invention, an uneven plating layer is formed on a copper foil of a printed circuit board.
Further, since the upper surface is processed by being covered with a synthetic resin, the printed circuit board can be processed only by laser processing without removing the copper foil in advance as in the related art.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a state in which a plating layer is formed on a printed board.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a process diagram showing a state in which a coating layer is formed.

FIG. 4 is a process diagram showing a drilled state.

FIG. 5 is a process chart showing a cleaning state.

FIG. 6 is a process chart showing a state of formation of a plating layer.

FIG. 7 is a process chart showing a state of forming a circuit pattern.

FIG. 8 is a process chart showing a state of forming a resist film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Copper foil 3 Coating layer 5 Laser beam

Claims (1)

(57) [Claims] 1. A synthetic resin substrate having a thickness of 3 μm
A synthetic resin that forms a bumpy plating layer having a thickness of several μm to 10 μm on the surface of a printed circuit board formed by attaching a copper foil of m to 7 μm, and absorbs the energy of laser light on the surface of the plating layer. And irradiating the substrate with a laser beam to form a hole in the printed circuit board.