KR100630913B1 - Manufacturing method of printed circuit board - Google Patents

Abstract

The present invention relates to a method of manufacturing a printed circuit board. According to an exemplary embodiment of the present invention, the first insulating layer 10 may be disposed to cover the first circuit pattern 12 on the first insulating layer 10 provided therein and having the first circuit pattern 12 formed on both surfaces thereof. Sequentially stacking the second insulating layer 20 and the metal layer 22 'on the surface, and selectively removing the metal layer 22' and the second insulating layer 20 to form the first circuit pattern 12. Forming a blind hole 25 to be selectively exposed, and installing a plating mask 40 on the surface of the metal layer 22 'so that plating is performed only inside the blind hole 25 so as to perform the first circuit pattern. And forming a connection protrusion 50 electrically connecting the metal layer 22 'and the metal layer 22' to form the second circuit pattern 22 by selectively removing the metal layer 22 '. It is configured by. In the present invention, a smaller circuit pattern can be formed and the space occupied by the configuration for the electrical connection of the circuit patterns on different layers can be reduced, thereby miniaturizing the printed circuit board, and in particular, using the existing equipment and materials. Since it is possible to form a fine, the manufacturing cost of the printed circuit board is relatively low, and the quality of the printed circuit board is improved because the circuit pattern between the layers is connected using plating.

Printed Circuit Boards, Interlayer Connections, Plating

Description

Manufacturing method of printed circuit board

1 is a cross-sectional view showing the configuration of a printed circuit board according to the prior art.

Figure 2a to Figure 2j is a work flow diagram showing a preferred embodiment of a method of manufacturing a printed circuit board according to the present invention sequentially.

Explanation of symbols on the main parts of the drawings

10: first insulating layer 12: first circuit pattern

20: second insulating layer 22: second circuit pattern

22 '; Metal layer 25: blind hole

30: electroless plating layer 40: plating mask

50: splice

The present invention relates to a printed circuit board, and more particularly, to a method of manufacturing a printed circuit board is formed such that a circuit pattern is formed on a plurality of insulating layers and the circuit patterns of different layers are electrically connected.

1 illustrates a cross-sectional configuration of a general multilayer printed circuit board. As shown in the drawing, a circuit pattern 5 is formed in each insulating layer 3 forming the printed circuit board 1. The circuit pattern 5 is made by selectively removing the metal layer 5 '.

In addition, blind via holes 7 for electrically connecting the circuit patterns 5 in different layers to each other are formed, and plating layers 7 ′ are formed on inner surfaces of the blind via holes 7 to form different layers. Electrically connect the circuit pattern (5) in the. The plating layer 7 'is formed on both the surface of the metal layer 5' and the inner surface of the blind bead hole 7 at the time of formation.

In forming the multilayer printed circuit board as described above, the circuit pattern 5 is first formed on one insulating layer 3, and the insulating layer 3 and the metal layer 5 ′ are formed on the circuit pattern 5 again. Form. In order to electrically connect the circuit patterns 5 on the different layers, the blind bead hole 7 is drilled and the plating layer 7 'is formed on the surface of the metal layer 5' and the inner surface of the blind bead hole 7. do. Next, the metal layer 5 'and the plating layer 7' are selectively removed to form a circuit pattern 5 on the insulating layer 3. By repeating the formation of the circuit pattern 5 on the insulating layer 3 in this manner, the multilayer printed circuit board 1 is manufactured.

However, the conventional method of manufacturing a printed circuit board as described above has the following problems.

That is, in order to electrically connect the circuit patterns 5 of different layers, the plating layer 7 ′ is formed on both the metal layer formed on the insulating layer 3 and the inner surface of the bladder hole 7. Therefore, the plating layer 7 'is coated on the metal layer provided on the upper surface of the insulating layer 3, and the thickness thereof becomes relatively large.

However, when the combined thickness of the metal layer and the plating layer 7 ′ is increased, it is difficult to form the circuit pattern 5 finely in the case of forming the circuit pattern 5 by selectively removing it. This is because the metal layer 5 'and the plating layer 7' must be immersed in the etching solution for a long time in the process of selectively removing the layers (the metal layer 5 'and the plating layer 7') which become the circuit pattern 5. to be.

In addition, in the prior art, the blind via hole 7 is used to electrically connect the circuit patterns 5 of different layers. The blind via hole 7 is not used for electrical connection therein and is filled with an insulating material. There is a problem that the space occupies a relatively large space. In addition, in the structure using the blind bead hole (7), because the land portion should be provided at the inlet edge of the blind bead hole (7), this also hinders the light and thin shortening of the printed circuit board.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above, and to refine the circuit pattern formed on the printed circuit board.

Another object of the present invention is to minimize the space occupied by the connection structure connecting the circuit patterns in different layers.

Still another object of the present invention is to reduce the thickness of a printed circuit board while using existing equipment and raw materials.

Still another object of the present invention is to completely fill the inside of a via hole formed by laser processing with a plating method, so that both the circuit design and the via hole are filled with plating, which does not require the formation of additional lands at the edges of the via hole. By providing a shape design, the printed circuit board is made thin and thin.

According to a feature of the present invention for achieving the above object, the present invention is relatively provided inside the first circuit pattern to cover the first circuit pattern on the first insulating layer having a first circuit pattern formed on the surface Sequentially stacking a second insulating layer and a metal layer on the surface of the insulating layer, selectively removing the metal layer and the second insulating layer to form a blind hole to selectively expose the first circuit pattern, and the metal layer Forming a connection protrusion for completely filling the inside of the blind hole electrically connecting the first circuit pattern and the metal layer by installing a plating mask on the surface of the blind hole so as to perform plating only on the inside of the blind hole, and selectively forming the metal layer. And removing to form a second circuit pattern including the connection protrusion.

In order to form the blind hole, the metal layer is selectively removed through an exposure, development and etching process, and the second insulating layer is removed using a laser or plasma as a light source.

Forming a connection protrusion in the blind hole may include forming an electroless plating layer on the metal layer, an inner wall of the blind hole, and a first circuit pattern exposed to the blind hole, and forming a plating mask to expose the blind hole. Covering the metal layer, and performing the electroplating in the blind hole to form the connecting projection.

After forming the connecting projections, removing the plating mask for the formation of the connecting projections, and in the state in which the plating mask is removed to remove the portion of the connecting projection protruding to the top of the metal layer to flatten the surface The step is further performed.

The forming of the connecting protrusion may be replaced by forming the connecting protrusion in the blind hole by plating or paste printing in the state where the metal layer is exposed.

The paste is a conductive paste.

According to the present invention having such a configuration in the manufacture of a multi-layer printed circuit board to form a finer circuit pattern and at the same time the space occupied by the configuration for the electrical connection of the circuit patterns on different layers to reduce the size of the printed circuit board In particular, the circuit pattern can be minutely formed using existing equipment and materials, so that the manufacturing cost of the printed circuit board is relatively low, and the quality of the printed circuit board is improved by connecting the circuit pattern between layers using plating. There is an advantage.

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

FIG. 2A to FIG. 2J show a work flow diagram sequentially showing a preferred embodiment of a method of manufacturing a printed circuit board according to the present invention. Accordingly, the first circuit pattern 12 is formed on both surfaces of the first insulating layer 10. Second insulating layers 20 are provided on both surfaces of the first insulating layer 10 to cover the first circuit pattern 12. The metal layer 22 ′ is provided on the surface of the second insulating layer 20.

The first circuit pattern 12 may be formed of a substrate (for example, an operation laminate) having a metal layer (not shown) for forming the first circuit pattern 12 on both surfaces of the first insulating layer 10. It is formed by selectively removing the metal layer. The second insulating layer 20 and the metal layer 22 ′ may be compressed on both surfaces of the first insulating layer 10 on which the first circuit pattern 12 is formed. As shown in FIG. 2A, the structure of the laminate 9 in which the second insulating layer 20 and the metal layer 22 ′ are formed on both surfaces of the first insulating layer 10 on which the first circuit pattern 12 is formed is shown. have.

Next, the metal layer 22 'is selectively removed to form the opening 23. The opening 23 is formed at the position where the connecting projection 50 will be described below. The opening 23 may be formed by exposing, developing, and etching the metal layer 22 ′. Of course, the opening 23 may be formed in various ways such as using a mechanical drill. The state in which the opening 23 is formed is shown in FIG. 2B.

Next, the second insulating layer 20 in the portion where the opening 23 is formed is removed to form the blind hole 25. The blind hole 25 is formed by removing the second insulating layer 20 using a laser or plasma as a light source. The blind hole 25 exposes the first circuit pattern 12 formed in the first insulating layer 10. This state is shown in FIG. 2C.

After the blind hole 25 is formed, a metal layer is formed on the exposed surface of the laminate 9 by electroless plating or sputtering. In this embodiment, the use of the electroless plating method will be described. When electroless plating is performed, the second insulating layer 20 exposed on the surface of the metal layer 22 ′, the inner wall of the blind hole 25 and the first circuit pattern 12 exposed on the blind hole 25 are formed. ), As shown in FIG. 2D, an electroless plating layer 30 is formed. The electroless plating layer 30 subsequently serves as a power connection during copper plating for forming the connecting protrusion 50 and copper plating is applied to the second insulating layer 20 exposed on the inner wall of the blind hole 25. It serves as a seed layer that can be made.

After performing electroless plating, the plating mask 40 is covered on the exposed surface of the laminate 9, in particular the surface of the metal layer 22 '. The plating mask 40 serves to prevent plating on the surface of the metal layer 22 '. As the plating mask 40, a dry film or a peelable may be used. The plating mask 40 is covered with the metal layer 22 ′ in FIG. 2E.

A portion of the plating mask 40 corresponding to the blind hole 25 is selectively removed. The state corresponding to the blind hole 25 is removed in FIG. 2F. Selectively removing the plating mask 40 may be performed by selectively irradiating light to the plating mask 40 to selectively remove only a portion corresponding to the blind hole 25.

Next, the connecting protrusion 50 is formed in the blind hole 25. There are a variety of ways to form the connecting projection (50). That is, the electroplating method, the method of printing a conductive paste, etc. are mentioned. Of course, when the paste is printed to form the connecting projection 50, the electroless plating layer 30 may not be formed. In this embodiment, the electrolytic plating method is adopted. 2G illustrates a state in which the connecting protrusion 50 is formed by electroplating. As the connecting protrusion 50 is formed, the first circuit pattern 12 and the metal layer 22 'are completely electrically connected as a ratio. When the connecting protrusion 50 is formed by electroplating, the inside of the blind hole 25 is completely filled, and the plating is continued to complete the filling so that the upper end of the connecting protrusion 50 is The upper end is convex in a dome shape or mushroom shape so as to protrude from the surface of the laminate 9.

After the connection protrusions 50 are formed, the plating mask 40 is removed as shown in FIG. 2H. After removing the plating mask 40, the portion of the connecting protrusion 50 protruding from the surface of the metal layer 22 ′ is removed to flatten the surface of the laminate 9. This can be removed using a polishing apparatus. At this time, the electroless plating layer 30 formed on the metal layer 22 'may or may not be removed, but in order to flatten the surface of the laminate 9, part of the electroless plating layer 30 may be removed during polishing. . A state in which the protruding tip of the connecting protrusion 50 is removed is shown in FIG. 2I.

On the other hand, the connection layer 50 formed by the metal layer 22 'and the plating is substantially integrated. This is because the connection protrusion 50 is formed on the metal layer 22 ′ corresponding to the edge of the inner surface of the inlet of the blind hole 25 by plating. Thus, the electrical connection between them is assuredly made.

Next, a portion of the metal layer 22 ′ including the connection protrusion 50 provided on the second insulating layer 20 is selectively removed to form the second circuit pattern 22. The second circuit pattern 22 is electrically connected to the first circuit pattern 12 through the connection protrusion 50. In addition, since the connection protrusion 50 is formed of a copper layer, the upper end of the connection protrusion 50 functions as a direct circuit pattern without the need for the formation of lands by an additional plating process. As described above, the second circuit pattern 22 is formed in FIG. 2J.

After the outermost circuit pattern 22 is formed as described above, a gold plated layer is formed on the portion where the device is mounted or the wire is bonded, and an insulating material for protection is applied to the surface of the printed circuit board to complete the printed circuit board. do.

For reference, although the circuit patterns 12 and 22 are formed of a total of four layers in the illustrated embodiment, the printed circuit board of six layers and eight layers may be repeatedly formed in the same manner as described above. have.

Hereinafter, the operation of the method of manufacturing a printed circuit board according to the present invention having the configuration as described above will be described in detail.

In the present invention, the circuit patterns 12 and 22 provided on the different layers are electrically connected using the connection protrusions 50. Since the connection protrusion 50 has no empty space therein, even if the diameter thereof is relatively small, electrical connection between the circuit patterns 12 and 22 may be sufficiently performed. That is, the electrical connection between the circuit patterns 12 and 22 can be completely performed without occupying unnecessary space.

In particular, in forming the connecting protrusion 50, since the plating layer or the like is not added to the surface of the metal layer 22 ', the thickness of the metal layer 22' forming the second circuit pattern 22 is kept relatively thin. do. Therefore, the second circuit pattern 22 can be formed relatively finely. This is because the thickness of the metal layer 22 'is relatively thin, so that the time required for etching is relatively short.

On the other hand, in the present invention, there is no process requiring new equipment or materials in the process configuration for forming a printed circuit board. Most equipment such as equipment for laminating the insulating layers 10 and 20 and the metal layer 22 ', equipment for selectively removing the insulating layers 10 and 20 and the metal layer 22', and equipment necessary for plating This equipment was used in the existing process.

In addition, the raw materials used in the manufacture of the printed circuit board of the present invention is also used in the past, the plating mask is also used generally used dry film.

In the present invention, when the plating process is used to form the connection protrusions 50, the connection protrusions 50 and the metal layer 22 ′ are substantially integrated with each other by plating, ie, the first circuit pattern. The electrical connection between the 12 and the second circuit pattern 22 is made more secure.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

In the method of manufacturing a printed circuit board according to the present invention as described in detail above, the following effects can be obtained.

First, in the present invention, in forming the second circuit pattern on the second insulating layer, the thickness of the metal layer serving as the parent is kept relatively thin, so that the etching time is shortened. Therefore, the second circuit pattern can be formed more finely, so that the printed circuit board can be made light and thin.

Next, in the present invention, there is no unnecessary space inside the connection protrusion for electrically connecting the first and second circuit patterns in different layers. Therefore, the pitch between the connecting projections can be relatively reduced, so that the printed circuit board can be made light and thin.

In the present invention, since the connecting protrusions for electrically connecting the first and second circuit patterns in different layers are substantially integrated with the first and second circuit patterns formed through plating, the electrical connection between them is assured. As a result, the quality of the printed circuit pattern is improved.

In addition, the present invention can manufacture a printed circuit board using the existing equipment and raw materials as it is. Therefore, the printed circuit board can be made relatively thin and short, and the manufacturing cost can be relatively low.

Finally, in the present invention, the inside of the via hole formed by laser processing is completely filled with a plating method to provide a circuit design that does not require the formation of additional lands on the upper side of the via hole, and the via hole is filled with plating, thereby providing a design of a printed circuit board. It is effective to reduce the light and small.

Claims (6)

Sequentially stacking a second insulating layer and a metal layer on a surface of the first insulating layer so as to cover the first circuit pattern on a first insulating layer provided inside and having a first circuit pattern formed on a surface thereof; Selectively removing the metal layer and the second insulating layer to form a blind hole to selectively expose the first circuit pattern; Installing a plating mask on the surface of the metal layer so that plating is performed only inside the blind hole to form a connection protrusion which completely fills the inside of the blind hole electrically connecting the first circuit pattern and the metal layer; Selectively removing the metal layer to form a second circuit pattern including the connection protrusions. The printed circuit board of claim 1, wherein the metal layer is selectively removed through an exposure, development, and etching process to form the blind hole, and the second insulating layer is removed using a laser or a plasma as a light source. Manufacturing method. The method of claim 1 or 2, wherein the connecting projection is formed in the blind hole. Forming an electroless plating layer on the metal layer, an inner wall of the blind hole, and a first circuit pattern exposed to the blind hole; Applying a plating mask on the metal layer to expose the blind hole; And forming the connection protrusion by performing electroplating on the blind hole. The method of claim 1, further comprising: removing the plating mask for forming the connecting protrusion after forming the connecting protrusion; And removing the portion of the connecting protrusion protruding to the upper portion of the metal layer in the state where the plating mask is removed, thereby flattening the surface of the printed circuit board. The method of claim 1, wherein the forming of the connecting projections comprises: And forming a connecting protrusion in the blind hole by a plating method or a paste printing method in a state where the metal layer is exposed. The method of claim 5, wherein the paste is a conductive paste.

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