KR100670594B1 - Method of forming a fine circuit for printed circuit board - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board manufacturing technology, and more particularly, to a method of manufacturing a fine circuit on a printed circuit board and a printed circuit board to which the same is applied.

The present invention makes it possible to fabricate a printed circuit board having a fine pattern by using a prepreg without a copper foil layer instead of a prepreg having a conventional copper foil layer and forming a copper plating layer to form an outer layer printed circuit board.

Printed circuit board, prepreg, copper foil.

Description

METHOD OF FORMING A FINE CIRCUIT FOR PRINTED CIRCUIT BOARD}

1A to 1D illustrate a process of constructing a circuit on an outer layer board laminated on an inner layer circuit board according to the prior art;

2a to 2e are views showing a printed circuit board manufacturing method according to the present invention.

<Explanation of symbols for main parts of the drawings>

10: inner layer circuit board

20a, 20b: insulation layer disc

30: dry film

51: solder plating layer

70: prepreg

71: copper plating layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board manufacturing technology, and more particularly, to a method of manufacturing a fine circuit on a printed circuit board and a printed circuit board to which the same is applied.

Recently, as portable electronic devices are widely used, the size of a printed circuit board is also reduced, and the line width length of circuits manufactured on the printed circuit board is also tended to be miniaturized.

1A to 1D are views illustrating a process of constructing a circuit in an outer layer plate laminated on an inner layer circuit board according to the prior art. Referring to FIG. 1A, according to the prior art, a prepreg 20b covered with a copper foil 20a having a thickness of about 17 to 35 μm is thermally compressed onto an inner circuit board 10, for example, by using a four-layer substrate. To form.

Subsequently, referring to FIG. 1B, in order to form a circuit in the first layer, the dry film 30 is patterned and copper plated on the exposed portion, followed by solder plating. Subsequently, when the dry film 30 is removed, a shape as shown in FIG. 1C is formed.

That is, referring to FIG. 1C, a patterned copper plating layer 50 and a solder plating layer 51 are formed on the copper foil 20a. When the solder plating layer 51 is used as a hard mask and an alkaline etching solution is used, the copper foil layer 20a can be etched. As a result, the copper foil layer 20a on a prepreg is etched and a circuit is formed.

However, in the prior art illustrated in FIGS. 1A to 1D, the etching profile has a sloped surface as shown by reference numeral 60 and reference numeral 62 in the wet etching step, which is not suitable for making a fine circuit. This is because when the etching profile has an inclined surface as shown in Fig. 1D, there may be a short circuit between adjacent conductive layers.

Furthermore, in the case of printed circuit boards of current portable electronic devices, the distance between circuits and circuits is narrow, so that there is a risk of the copper foils sticking to each other and electrically shorted to the insulating layer when the prior art is applied.

Accordingly, the present invention is to provide a printed circuit board manufacturing method capable of forming a fine circuit pattern.

In order to achieve the above object, the present invention provides a method for manufacturing a multilayer circuit printed board comprising the steps of: (a) laminating a prepreg insulating layer not covered with a copper foil layer on a patterned inner layer circuit board; (b) performing copper plating on the surface of the insulating layer; (c) pattern forming a dry film for forming a circuit pattern on the copper plating surface; (d) subsequently performing a copper plating layer and a solder plating layer on the patterned surface of the dry film; And (e) peeling off the dry film, and etching the copper plating layer using the solder plating layer as a mask to form a circuit pattern of an outer layer circuit.

Hereinafter, a manufacturing method of a printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings, FIGS. 2A to 2E.

The prior art has made it difficult to form a fine pattern by using the insulating layer disk (20a, 20b) is attached to the prepreg copper foil of several tens of microns thick. Therefore, this invention provides the construction method which can make thickness of a base copper foil thin.

Referring to Fig. 2A, the present invention is characterized in that a prepreg 70 having no copper foil is laminated on the inner circuit board 10 is laminated. Then, on the prepreg insulating layer 70 which is not covered with copper foil, a thin copper plating layer 71 of about 1 micron is formed through plating, preferably through chemical plating.

Referring to FIG. 2B, a copper plating layer 71 is formed on the prepreg 70 having no copper foil layer. Here, it is preferable that the prepreg 70 without a copper foil layer forms roughness, and has sufficient plating adhesive force.

As a preferred embodiment of the present invention, it is preferable that the prepreg 70 without the copper foil layer has a plating adhesion strength of 0.4 kgf / cm or more. As an embodiment of the prepreg according to the present invention, additive prepreg of Matsushita Electronics Co., Ltd. may be used.

Referring to FIG. 2C, the dry film 30 is patterned, and copper plating 50 and solder plating layer 51 are formed (see FIG. 2D). Then, since the copper plating layer 71 on the prepreg 70 is very thin (~ 1 micrometer), it can soft-etch with the solution, such as hydrochloric acid and a water peroxide, and can form a pattern circuit.

At this time, since the thickness of the copper foil to be etched is only about 1 μm, the etching cross section can be taken almost vertically. As a result, the problem of the inclined plane of the etching profile experienced by the prior art is solved.

The foregoing has outlined rather broadly the features and technical advantages of the present invention to better understand the claims of the invention which will be described later. Additional features and advantages that make up the claims of the present invention will be described below. It should be appreciated by those skilled in the art that the conception and specific embodiments of the invention disclosed may be readily used as a basis for designing or modifying other structures for carrying out similar purposes to the invention.

In addition, the inventive concepts and embodiments disclosed herein may be used by those skilled in the art as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. In addition, such modifications or altered equivalent structures by those skilled in the art may be variously evolved, substituted and changed without departing from the spirit or scope of the invention described in the claims.

As described above, the present invention uses a prepreg without a copper foil layer instead of a prepreg having a conventional copper foil layer and forms a copper plating layer to form an outer layer printed circuit board, thereby making a printed circuit board with a fine pattern possible. do.

Claims (2)

In the method of manufacturing a multilayer circuit printed board, (a) laminating a prepreg insulating layer not covered with a copper foil layer on an inner circuit board having a circuit patterned with copper foil; (b) copper plating the surface of the insulating layer; (c) pattern forming a dry film for forming a circuit pattern on the copper plating surface; (d) subsequently performing a copper plating layer and a solder plating layer on the patterned surface of the dry film; And (e) removing the dry film and etching the copper plating layer using the solder plating layer as a mask to form a circuit pattern of an outer layer circuit Printed circuit board manufacturing method comprising a. The method of manufacturing a printed circuit board according to claim 1, wherein the prepreg not covered with the copper foil layer has a plating adhesion strength of 0.4 kgf / cm or more.

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