KR100772432B1 - Method of manufacturing printed circuit board - Google Patents

Abstract

A manufacturing method of a PCB(Printed Circuit Board) is provided to prevent the short between adjacent pads by forming a bonding pad through electrolytic copper plating after nickel electrolytic plating. A manufacturing method of a PCB includes the steps of: forming dry film patterns on upper/lower surfaces of a copper foil carrier of predetermined thickness; performing electrolytic nickel coating(120) on the copper foil carrier pattern; performing electrolytic copper coating(130) on the electrolytic nickel coating layer; exfoliating the dry film pattern, and laminating a prepreg(150) and a copper foil single surface; forming a through hole by laser processing, and forming an electrolytic copper pattern on the copper foil single surface; masking the electrolytic copper pattern with the dry film, and etching the copper foil carrier; performing electroless gold coating(121) on the exposed nickel surface; and exfoliating the dry film and forming a solder resist(250) for wire bonding.

Description

Printed circuit board manufacturing method {METHOD OF MANUFACTURING PRINTED CIRCUIT BOARD}

1A-1I illustrate a method for manufacturing a packaged printed circuit board according to the prior art.

2A and 2B are cross-sectional views of bonding pads manufactured according to the prior art when the pitch length is miniaturized.

3a to 3l illustrate a method for manufacturing a package substrate according to the present invention in detail.

<Explanation of symbols for main parts of the drawings>

10: resin insulation layer

11, 12: copper foil

13: through hole

14, 15: dry film pattern

16, 17, 18: bonding pad

110: dry film

120: nickel plated

130: copper plating

150: prepreg

160: copper foil foil one side

170: via hole

200: electrophoretic pattern

250 soldering resist

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a printed circuit board, and more particularly, to a method of manufacturing an ultra-thin package printed circuit board having a fine pitch length of a bonding pad.

In recent years, as a printed circuit board becomes ultra thin, the pitch length of a wire bonding pad requires 80 micrometers or less, and the ultra thin plate of 0.04t and 3 micrometers copper foils is applied.

1A to 1I illustrate a method of manufacturing a package printed circuit board according to the prior art. Referring to FIG. 1A, a substrate having copper foils 11 and 12 coated on top and bottom surfaces of a resin insulating layer 10, such as a prepreg or a copper claded layer (CCL), may be used to reduce the thickness of the copper foil. Polish as thin as 3 μm to μm.

Subsequently, as shown in FIG. 1B, the through hole 13 is processed through laser processing and the dry film patterns 14 and 15 are formed to pattern the site where the wire bonding pad is to be manufactured.

Referring to FIG. 1C, bonding pads 16, 17, and 18 are formed through a copper plating process (commonly referred to as SAP plating, where SAP stands for semi-additive plating). Referring to FIG. 1D, the dry films 14 and 15, which were used as masks in the copper plating process, are peeled off and the copper foil surface is slightly etched through flash etching. Subsequently, referring to FIG. 1E, the resin-coated copper foil (RCC) 20 substrate is pressed and laminated on the upper and lower surfaces.

Subsequently, referring to FIG. 1F, the dry film patterns 21 and 22 are formed to open the copper foil and undergo a plasma etching process. Referring to FIG. 1G, a chemical copper feed circuit is formed, followed by soft etching Ni / Au and peeling dry film in the process of FIG. 1H. Finally, the package is completed by cleaning the surface through plasma etching as shown in FIG. 1I.

However, when fabricating a package printed circuit board according to the above-described prior art, a problem arises as the pitch length of the bonding pad becomes smaller.

2A and 2B are cross-sectional views of bonding pads manufactured according to the prior art when the pitch length is miniaturized. For example, in a design rule having a pitch length of 80 μm, when the length of the bonding pad is 55 μm, the distance between adjacent bonding pads is about 25 μm. Referring to FIG. 2A, in the prior art, a pad is reinforced to supplement pad top etching, and there is a risk of an electrical short between adjacent pads 17 and 18. In addition, referring to FIG. 2B, after the SAP plating is formed on the substrate, the cross section of the pad is inclined due to an etch factor in the process of peeling off the dry film and performing flash etching in the subsequent electrolytic soft Ni / Au plating step. There is a risk of an electrical short.

Accordingly, a first object of the present invention is to provide a method of manufacturing a package printed circuit board having a fine pitch length between bonding pads.

A second object of the present invention is to provide a method of manufacturing a package printed circuit board which can be applied to an ultra-thin printed circuit board in addition to the first object.

A third object of the present invention is to provide a package printed circuit board manufacturing method in which, in addition to the first object, an electrolytic Ni / Au plating lead-in circuit forming process for a bonding pad is not required.

In order to achieve the above object, the present invention provides a method for manufacturing a package printed circuit board having a bonding pad (a) forming a dry film on the upper and lower surfaces of a copper foil carrier of a predetermined thickness; (b) forming an electrolytic nickel plating on the portions where the copper foil is exposed to the dry film pattern; (c) forming an electrolytic copper plating on the electrolytic nickel plating layer; (d) peeling off all the patterned dry films and laminating the prepreg and one side of the copper foil; (e) forming a through hole by laser processing and forming an electrophoretic pattern on one side of the copper foil; (f) masking the copper copper pattern with a dry film and etching away the copper foil carrier; (g) performing electroless gold plating on the exposed nickel surface as a result of step (f); And (h) peeling off the dry film and forming a solder resist for wire bonding.

Hereinafter, a method for manufacturing a package substrate according to the present invention will be described in detail with reference to FIGS. 3A to 3L. Referring to FIG. 3A, a 300 μm thick copper foil 100 is prepared to form a dry film 110 as shown in FIG. 3B. Referring to FIG. 3C, electrolytic nickel plating 120 is performed on the copper foil 100 patterned with a dry film about 5 to 10 μm. Referring to FIG. 3D, the electrolytic copper plating 130 is further processed to about 10 to 20 μm on the substrate on which the electrolytic Ni is plated.

Referring to Figure 3e, the dry film is peeled off. Subsequently, referring to FIG. 3F, a prepreg 150 and a copper foil foil 160 having a thickness of, for example, 0.04 to 0.1t are stacked on the bonding pad formed of the Ni electrolytic plating layer 120 and the electrolytic copper plating 130.

Referring to FIG. 3G, via holes 170 may be formed through laser processing, and electrophoretic patterns 200 may be formed. Referring to FIG. 3H, the dry film 210 is masked and the copper foil carrier 100 is etched. Next, referring to FIG. 3I, the electroless gold plating 121 is advanced, and preferably about 1 μm is coated.

Referring to FIG. 3J, the dry film is peeled off to form a soldering resist 250. Subsequently, referring to FIGS. 3K and 3L, the solder surface 251 is finished and plasma cleaned through a selective organic solderable preservative (SOSP) or dry film mask and electroless nickel immersion gold (ENIG).

The foregoing has somewhat broadly improved the features and technical advantages of the present invention to better understand the claims that follow. 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, since the present invention forms a bonding pad by performing electrolytic copper plating after nickel electroplating, the problem of reduction in pad size experienced in the prior art does not occur, and as a result, a problem of shorting between adjacent pads can be solved. .

In addition, in the case of the present invention, since the pad is manufactured on the upper and lower surfaces of the copper foil carrier of about 300 μm, the thickness of the substrate is secured to 300 μm or more, and thus there is an advantage that existing equipment can be used as it is. Furthermore, in the present invention, there is an advantage that a separate wiring process for Ni / Au plating is omitted before the independent pad.

Claims (1)

In the method of manufacturing a package printed circuit board having a bonding pad, (a) pattern-forming a dry film on upper and lower surfaces of a copper foil carrier of a selected thickness; (b) forming an electrolytic nickel plating on the portions where the copper foil is exposed to the dry film pattern; (c) forming an electrolytic copper plating on the electrolytic nickel plating layer; (d) peeling off all the patterned dry films and laminating the prepreg and one side of the copper foil; (e) forming a through hole by laser processing and forming an electrophoretic pattern on one side of the copper foil; (f) masking the copper copper pattern with a dry film and etching away the copper foil carrier; (g) performing electroless gold plating on the exposed nickel surface as a result of step (f); And (h) peeling off the dry film and forming a solder resist for wire bonding Package printed circuit board manufacturing method comprising a.

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