KR20040058416A - Method for plating copper in pcb - Google Patents

Abstract

PURPOSE: A method for plating copper in PCB is provided to reduce the thickness of a copper plating etched when forming a second hole and to prevent a short-circuit or open-circuit by forming uniformly the copper plating. CONSTITUTION: A method for plating copper in PCB comprises a step of providing a printed circuit board(100) where a first copper thin film(120), a synthetic resin(110), and a second copper thin film(130) are layered, a step of forming a first hole passing through the PCB, a step of forming an anti-coating film(140) for exposing the first hole on the PCB, a step of forming a copper plating film(150) at the inner wall of the first hole, a step of removing the anti-coating film, and a step of forming a second hole by etching a predetermined part of the second copper thin film.

Description

Copper plating method of printed circuit board {Method for plating copper in PCB}

The present invention relates to a copper plating method of a printed circuit board, and more particularly, to a method of performing copper plating only on the inner wall of a hole of a printed circuit board.

In response to the demand for high performance devices due to miniaturization, high speed, and high frequency, the development of new printed circuit boards suitable for high density wiring and high density mounting is also in progress.

Currently, a basic printed circuit board (PCB) for system configuration of various automation machines such as a computer is formed by processing a synthetic resin prepreg in which a thin copper film is coated on the top and bottom by a plating process. Are manufactured. In the synthetic resin disc, a plurality of component insertion holes, circuit connection holes, and the like are formed to penetrate the upper and lower surfaces thereof, and inner walls of the plurality of holes are electroplated to perform basic operations as electrical circuits.

1A to 1F are cross-sectional views of respective processes for explaining a method of plating a copper film on a hole inner wall of a conventional printed circuit board.

Referring to FIG. 1A, first and second copper thin films 12 and 14 are coated on upper and lower surfaces of a synthetic resin (prepreg: 10) to prepare a printed circuit board 20. In this case, the first or second copper thin films 12 and 14 may have a thickness of, for example, 12 μm, 18 μm, or 36 μm.

As shown in FIG. 1B, the second copper thin film 14, the synthetic resin 10, and the first copper thin film 12 are drilled to form a first hole H1 to which component insertion and / or a circuit are connected. .

Then, as shown in Fig. 1C, the copper plating film 16a is coated by the copper plating method using the sulfuric acid solution on the inner wall of the first hole H1. In this process, the copper plating film 16b is simultaneously coated on the first and second copper thin film surfaces. At this time, although the copper plating films 16a and 16b differ slightly depending on the diameter of the first hole H1, the copper plating films 16a and 16b are plated to a thickness of approximately 18 μm or more.

Referring to FIG. 1D, a dry film 18 for a mask for defining other connection holes is formed on the upper surface of the printed circuit board 20 in a known manner.

As illustrated in FIG. 1E, the copper plating film 16b and the second copper thin film 14 are etched in the form of a dry film 18 to form a second hole H2.

Next, as shown in FIG. 1F, the dry film 18 is peeled off.

However, in the conventional copper plating method on a printed circuit board, when the copper plating film 16a is coated on the inner wall of the first hole H1, the copper plating film 16b is also coated on the surface of the second copper thin film 14. In the subsequent formation of the second hole H2, the thickness of the copper film (second copper thin film and copper plating film) to be etched is increased. That is, since the second copper thin film 14 having a thickness of about 18 µm or more is coated on the synthetic resin 10, and the copper plating film 16b having a thickness of about 18 µm or more is coated on the synthetic resin 10, The thickness of the total copper film on the resin 10 is 36 µm or more. Therefore, when the second hole H2 is formed, the copper plating film 16b and the second copper thin film 16b are not completely etched, so that the shape of the second hole H2 becomes narrower toward the bottom. Is generated.

Moreover, since the panel size at the time of plating becomes 510 mm x 610 mm, for example, surface plating deviation arises. As such, when plating deviation occurs, when etching the second hole H2, a portion having a high etching rate and a portion thereof not being formed may be generated due to a difference in plating thickness, such that a short or an open may be defective. .

Accordingly, a technical object of the present invention is to provide a copper plating method of a printed circuit board capable of reducing the thickness of the copper film etched when forming the second hole of the printed circuit board.

In addition, another technical problem to be achieved by the present invention is to provide a copper plating method of a printed circuit board which can prevent a short or open phenomenon by making the thickness of the copper thin film deposited on the printed circuit board uniform.

1A to 1F are cross-sectional views of respective processes for explaining a method of plating a copper film on an inner wall of a hole of a conventional printed circuit board.

2A to 2G are cross-sectional views of respective processes for describing a copper plating method of a printed circuit board according to an exemplary embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: printed circuit board 110: synthetic resin

120: first copper thin film 130: second copper thin film

140: copper plating prevention film 150: copper plating film

160: dry film h1, h2: hole

In order to achieve the above object of the present invention, the present invention provides a printed circuit board in which the first copper thin film, the synthetic resin, and the second copper thin film are sequentially laminated. Next, a first hole is formed to penetrate the printed circuit board, and a plating prevention film is formed to expose the first hole on the printed circuit board. Then, a copper plating film is formed on the inner wall of the first hole, the plating prevention film is removed, and the second copper thin film of the printed circuit board is partially etched to form a second hole.

In the forming of the anti-plating layer, the anti-plating layer may be formed to extend by a predetermined length inward from the edge of the first hole.

It is preferable that the copper plating film is plated to a thickness equal to the length of the anti-plating film extending inward from the edge of the first hole.

The forming of the second hole may include forming a dry film to expose a predetermined portion on the printed circuit board, etching the second copper thin film of the printed circuit board using the dry film as a mask; And removing the dry film.

Other objects and novel features as well as the objects of the present invention will become apparent from the description of the specification and the accompanying drawings.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements. In addition, where a layer is described as being "on" another layer or semiconductor substrate, a layer may exist in direct contact with the other layer or semiconductor substrate, or a third layer therebetween. Can be done.

2A to 2G are cross-sectional views of respective processes for describing a copper plating method of a printed circuit board according to an exemplary embodiment of the present invention.

Referring to FIG. 2A, first and second copper thin films 120 and 130 are coated on the upper and lower surfaces of the synthetic resin 110 in a known manner to prepare a printed circuit board 100. In this case, the first or second copper thin films 120 and 130 may have a thickness of, for example, 12 μm, 18 μm, or 36 μm. Next, the second copper thin film 130, the synthetic resin 110, and the first copper thin film 120 are drilled to form a first hole h1 to which a component insertion and a circuit are connected.

As shown in FIG. 2B, a plating prevention film 140, for example, a dry film is formed on the second copper thin film 130. In this case, the plating preventing layer 140 also includes an opening op to open the first hole h1. In this case, the diameter of the opening op may be smaller than the diameter of the first hole h1, and the anti-plating film 140 may be formed inside the first hole h1 from the edge of the hole h1 of the printed circuit board 100. It may extend by a predetermined length (x1) toward.

Next, as shown in FIG. 2C, a copper (copper) film is plated on the resultant surface to form a copper plated film 150. Since the plating preventing film 140 is formed on the upper surface of the second copper thin film 130, the copper plating film 150 is formed only on the inner side wall of the first hole h1. In addition, the copper plating film 150 is preferably plated with a thickness of the length (x1) of the anti-plating film 140 extending toward the inside of the first hole h1.

2D, the anti-plating film 140 is peeled off in a known manner. Accordingly, the additional copper film is not plated at the time of copper plating on the second copper thin film 130.

Then, as shown in FIG. 2E, a second hole defining dry film 160 for inserting a part and connecting a circuit is formed on the second copper thin film 130.

As illustrated in FIG. 2F, the second copper thin film 130 is etched using the second hole-limited dry film 160 as a mask to form a second hole h2. At this time, since only the second copper thin film 130 is etched when the second hole h2 is etched, the etching is easy.

Next, as shown in FIG. 2G, the dry film 160 is removed in a known manner.

As described in detail above, according to the present invention, a plating prevention film is formed on the printed circuit board at the time of copper plating on the inner wall of the component insertion or circuit connection hole of the printed circuit board. As a result, the copper plating film is prevented from being incidentally plated on the printed circuit board, so that at the time of forming a hole formed by etching of the copper plating film, the thickness of the copper plating film to be etched is reduced. Therefore, hole formation is easy.

In addition, since an additional copper plating film is not formed on the printed circuit board, plating variation does not occur, so that holes can be produced without a problem of short or open.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. .

Claims (4)

Providing a printed circuit board on which a first copper thin film, a synthetic resin, and a second copper thin film are sequentially stacked; Forming a first hole through the printed circuit board; Forming a plating prevention layer on the printed circuit board to expose the first hole; Forming a copper plating film on an inner wall of the first hole; Removing the plating prevention film; And And etching a predetermined portion of the second copper thin film of the printed circuit board to form a second hole. The method of claim 1, wherein the forming of the anti-plating layer, And the anti-plating film is formed to extend from the edge of the first hole by a predetermined length in an inward direction. 3. The copper plating method of claim 2, wherein the copper plating film is plated to a thickness equal to a length of the anti-plating film extending inward from an edge of the first hole. The method of claim 1, wherein the forming of the second hole comprises: Forming a dry film to expose a predetermined portion on the printed circuit board; Etching the second copper thin film of the printed circuit board using the dry film as a mask; And And removing the dry film.