KR100873666B1 - Method of processing double-sided core for printed circuit board - Google Patents

Abstract

A method for manufacturing a double-sided core substrate for multilayered printed circuit board is provided to prevent bending of the substrate by not requiring a half etching process or a film tent process. A first copper foil(20,30) is prepared in an upper surface and a lower surface interposing an insulating layer(10). The second copper foil is selectively exposed by forming a pattern through an image process of one surface of an inner layer core substrate on the second copper foil while interposing a metal adhesive on the first copper foil. The insulating layer is selectively opened and exposed by selectively etching the first copper foil and the second copper foil according to the pattern. A hole is made by irradiating the laser on the insulating layer which is opened and exposed. The first copper foil is exposed by peeling off and removing the metal adhesive coated between the first and second copper foils.

Description

METHOD OF PROCESSING DOUBLE-SIDED CORE FOR PRINTED CIRCUIT BOARD}

1 is a view showing a process of laser processing the inner core substrate having a thin copper foil according to the prior art.

2A to 2G illustrate a process of fabricating an inner layer core substrate having a fine circuit pattern according to the prior art.

3A-3C illustrate a process for fabricating an inner core core substrate in accordance with a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

    10: insulation layer

    20: upper surface copper foil

    30: lower surface copper foil

40, 60: dry film

50, 110: through hole

    80: metal adhesive

90, 100: carrier copper foil

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of printed circuit boards, and to a process for producing through holes for energization between an upper layer and a lower layer on a double-sided core substrate. More specifically, the present invention relates to a method for fabricating an inner layer core substrate of a printed circuit board in which a pitch interval of several micrometers is required to form a fine circuit pattern, and a thermal conduction problem in a laser processing process for manufacturing a through hole. It relates to a manufacturing technology that can maintain the thickness of the copper foil while solving the problem.

In recent years, as electronic products become smaller and lighter, it is required to form fine copper foil circuit patterns having a circuit line width of several micrometers on a printed circuit board. In order to form a circuit having a pitch interval of several micrometers on a copper foil of a printed circuit board, the thickness of the copper foil must be thinned to several micrometers.

This is because, in the etching process for forming the copper foil circuit, when the copper foil is thick, the isotropic etching characteristic is etched not only in the vertical direction but also in the horizontal direction. This is because a problem arises in that all circuit patterns must be etched away.

However, when laser processing is carried out to fabricate through holes in an inner core substrate having copper foils formed on both surfaces with an insulating layer interposed therebetween, the thickness of the lower surface copper foil is several micrometers (for example, 3 to 5 μm). In this case, there is a problem that the copper foil is drilled because the heat radiation is not smooth.

1 is a view showing a process of laser processing the inner core substrate having a thin copper foil according to the prior art. Referring to FIG. 1, when the copper foils 20 on both sides constituting the inner core are thin-etched to a few micrometers, the copper foil melts because the conductivity of the copper foil that emits Joule heat generated by the laser beam is not good. Eventually, a defect may occur in which a hole is drilled in the lower copper foil.

However, when the thickness of the copper foil is increased, as described above, it is impossible to form a fine copper foil circuit pattern having a pitch interval of several micrometers. As a conventional technique for solving such a problem, the following technique combining a single-sided mask step using a dry film and a half etching process is commonly used in the art. 2A to 2G illustrate a process of fabricating an inner layer core substrate having a fine circuit pattern according to the prior art.

Referring to FIG. 2A, a copper foil circuit 20 is formed by opening a copper foil through an image process on an upper surface of an inner layer substrate covered with copper foil on an upper surface and a lower surface of the insulating layer 10. Subsequently, the copper foil 30 covered on the lower surface is tented by covering the dry film 40 only on the lower end surface to protect the copper foil 30.

Referring to FIG. 2B, half etching is performed to lower the thickness of the copper foil of the upper copper foil circuit 20 of the inner layer core substrate where the lower copper foil 30 is tented by the dry film 40.

Next, referring to FIG. 2C, a laser drill is performed for the purpose of manufacturing a through hole 50 for energizing between the upper circuit and the lower circuit. At this time, unlike the half-etched upper surface copper foil 20, the thickness of the lower surface copper foil 30 is thick, so that the thermal conductivity is made smoothly so that the copper foil is not penetrated.

Referring to Figure 2d, to remove the peeled dry film 40 to protect the lower surface copper foil (30). Next, in order to make the thickness of the lower surface copper foil 30 thin, the dry film 60 is tented on the upper surface copper foil 20 as shown in FIG. 2E.

Referring to FIG. 2F, after the upper surface copper foil 20 of the inner layer core substrate is tented by the dry film 60, the thickness of the lower surface copper foil 30 is etched thinly through half etching. Finally, the dry film is peeled off as shown in FIG. 2G.

However, the prior art illustrated in FIGS. 2A to 2G has a problem of generating a large number of defects in the process of mass production of a printed circuit board. That is, when the dry film is tented only on one surface of the substrate in the steps of FIGS. 2A, 2B, 2E, and 2F, the substrate may be bent due to a difference in both sides tension, and thus, a product defect may occur.

Accordingly, a first object of the present invention is to provide a method for manufacturing an inner core core substrate such that the copper foil is not perforated due to poor thermal radiation during laser processing for the manufacture of through holes.

A second object of the present invention is to provide a method for producing an inner layer core substrate that can form a fine copper foil circuit without the process of tenting using a dry film in addition to the first object.

In order to achieve the above object, the present invention provides a first copper foil on the upper and lower layers, respectively, in the method of processing the inner core substrate constituting the multilayer printed circuit board, with an insulating layer interposed therebetween, and the first copper foil. A pattern is formed on an image of one surface of the inner layer core substrate provided with the second copper foil therebetween with a metal adhesive thereon to selectively expose the second copper foil surface, and the first copper foil and the second copper foil are Selectively etching the exposed portion according to a pattern to selectively open and expose the insulating layer, manufacturing a through hole by irradiating a laser onto the opened and exposed insulating layer, and peeling off the metal adhesive to remove the second adhesive. It provides a method comprising the step of exposing the first copper foil by peeling off the copper foil.

Further, as a preferred embodiment of the present invention, the thickness of the first copper foil may be determined by the pitch length of the circuit pattern to be formed on the inner layer core substrate, and the thickness of the second copper foil may be thicker than the thickness of the first copper foil. .

Hereinafter, a method of manufacturing an inner layer core substrate according to the present invention will be described in detail with reference to FIGS. 3A to 3C. The present invention has a structure consisting of an insulating layer coated on both sides of a thin foil (for example, 3 to 5 μm) of copper foil, a carrier copper foil of a thick thickness (for example 16 μm or more) by a metallic adhesive on the thin copper foil It is a technical point to manufacture an inner-layer core board | substrate using the close_contact | adherence structure.

3A to 3C illustrate a process of manufacturing an inner core substrate in accordance with a preferred embodiment of the present invention. Referring to FIG. 3A, the inner core board according to the present invention is provided with a thin copper foil 20, 30 coated on the face of an insulating layer 10 of a resin or resin system, wherein a metal adhesive ( 2nd copper foils 90 and 100 of thick thickness are formed through 80.

Here, the first copper foils 20 and 30 of the present invention are actually copper foils on which a fine circuit pattern is to be formed, and the thickness of the first copper foils 20 and 30 is fine to about several micrometers (for example, 3 to 5 μm). It is determined by varying the pitch length of the pattern. In addition, the second copper foils 90 and 100 according to the present invention may be referred to as carrier copper foils, and the second copper foils 90 and 100 may be padded as carriers on the first copper foils 20 and 30. do.

Here, the second copper foil (90, 100) serves to disperse and radiate heat during laser processing, and as a result solve the problem that the first copper foil (20, 30) is perforated due to heat dissipation problem, unlike the prior art Can be. At this time, the heat conduction problem can be solved by making the first copper foil 20 and 30 and the second copper foil 90 and 100 adhere to each other with a metallic adhesive. After completing the process, the carrier copper foil is peeled off and removed.

Referring again to FIG. 3A, the upper surface copper foil of the inner core structure according to the present invention is opened. At this time, as the carrier copper foil of the upper surface, the second copper foil 90 and the first copper foil 20 on which the circuit pattern is to be formed are simultaneously etched by image work.

3B, the through hole 110 is manufactured by performing a laser drill process. At this time, in the case of the present invention, since the lower surface copper foil is made by the heat radiation is smoothly made by the second copper foil 100 that serves as a carrier copper foil there is no fear of perforating the copper foil. In addition, since there is no need for the tent method of the dry film for protecting the first copper foil 30 having a fine thickness, there is no problem of bending the substrate due to the difference in tensile coefficient.

Finally, referring to FIG. 3C, after the laser process is completed, the through holes 110 are formed and only the first copper foils 20 and 30 on which the fine patterns are to be formed are exposed by peeling off and removing the carrier copper foils 90 and 100. Subsequently, a post-process for forming a circuit of chemical copper, electrophoresis, etc. may be performed according to the prior art.

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 simplifies the process and prevents the bending problem of the substrate due to the dry film tent application by not using a process step such as a half etching or a dry film tent process unlike the prior art. . Moreover, the present invention solves the problem that the copper foil is perforated due to poor thermal radiation during laser processing by using a removable removable copper foil over a thin copper foil to form a circuit pattern.

Claims (3)

In the method of processing the inner core board constituting the multilayer printed circuit board, (a) An image of one surface of an inner core core substrate having a first copper foil on an upper layer and a lower layer with an insulating layer interposed therebetween, and having a second copper foil thereon with a metal adhesive interposed therebetween. Selectively forming a pattern to expose the surface of the second copper foil, and selectively etching the exposed portions of the first copper foil and the second copper foil according to the pattern to selectively open and expose the insulating film; (b) fabricating a hole by irradiating a laser onto the open and exposed insulating film; And (c) exposing the first copper foil by peeling off the second copper foil by peeling the metal adhesive applied between the first copper foil and the second copper foil. Inner layer core substrate processing method comprising a. The inner layer core of claim 1, wherein a thickness of the first copper foil is determined by a pitch length of a circuit pattern to be formed on the inner core board, and a thickness of the second copper foil is thicker than a thickness of the first copper foil. Substrate processing method. The multilayer printed circuit board produced by laminating | stacking an outer layer board | substrate on the inner layer core board | substrate produced by the method of any one of Claims 1 or 2.

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