KR19990048038A - Multi-layer printed circuit board manufacturing method - Google Patents

Abstract

In the method of manufacturing a multilayer printed circuit board of the present invention, the steps of forming a printed circuit pattern by plating and etching metal on both sides of the copper-clad laminate, and applying and developing the photosensitive insulating resin layer on the both sides of the copper-clad laminate by one cuttin coating method. Forming via holes, forming a through hole for interlayer conduction, and then forming a Cu plating layer on inner walls of the printed circuit pattern, the photosensitive insulating resin layer, and the through hole; and etching the Cu plating layer to form a printed circuit pattern. It is composed.

Description

Multi-layer printed circuit board manufacturing method

The present invention relates to a multilayer printed circuit board, and more particularly, to a method of manufacturing a build-up multi-layer printed circuit board with improved interlayer connection.

Since the development of electronic components and component embedding technology and the development of multilayer printed circuit boards overlapping circuit conductors, research on the densification of multi-layer printed circuit boards (Mulit-Layer Board) has been actively conducted. Among them, a method of manufacturing a multilayer printed circuit board by a build-up method is widely used. Unlike the conventional BHV method, an insulating layer and a circuit conductor layer are sequentially stacked. It is a method of forming a multilayer circuit. Therefore, the manufacturing of the printed circuit board by the build-up is not only simple in itself, but also the multilayer printed circuit board (i.e., the build-up MLB) manufactured accordingly is formed by the via hole forming the connection of the interlayer circuits of the substrate. It is easy to form, it is possible to form the microscopic via hole, and the thickness of the circuit conductor is thin, which has the advantage of easy formation of microcircuits.

A manufacturing method for such build-up MLB is disclosed in Japanese Patent Laid-Open No. 7-231171. According to the above patent, as shown in Figs. 1A to 1F, the primary photosensitive insulating resin 14 is coated on the conductor circuit board 10 on which the inner layer circuit 12 is formed and irradiated with light. By forming the first unexposed portion 15 larger than the desired via hole 20, the secondary photosensitive insulating resin 16 is applied continuously without developing. Thereafter, light is irradiated again to form a second unexposed portion 17 smaller than the first unexposed portion 15, and then the first unexposed portion 15 and the second unexposed portion 17 are developed. To form a via hole 20. Subsequently, UV curing and thermosetting, roughening by chromic acid, and a plating resist are formed, and then the outer layer conductor circuit 30 is formed only by electroless Cu plating to complete the build-up MLB.

However, in the above method, the first unexposed portion 15 and the second exposed portion 17 are formed in advance by the first and second exposures, and the first unexposed portion 15 and the second exposed portion 17 are described above. 1 (d) and 1 (e), the exposure weakening portion 22 is generated due to lack of proper light quantity transfer due to the thickness of the insulating resin layer, and after development, the via hole having a very small diameter is developed. The inlet 20 is narrow and the inner circuit side is widened. According to the shape of the hole, the plating liquid is not smoothly supplied in the hole during electroless Cu plating, and thus the plating weakening portion is generated, which causes the reliability of the plating contact.

In order to solve the above-mentioned problems, even when long exposure is performed and sufficient exposure amount is given, undeveloped or via hole diameters are reduced due to cracking and overhardening of the insulating resin. In addition, due to the shape of the hole, the size of the via hole is generally limited to about 0.2 mm, which reduces the formation of the via hole, resulting in a problem that the density of the multilayer printed circuit board is greatly limited.

Another method for manufacturing a multilayer printed circuit board for solving the various problems described above is disclosed in Korean Patent Application No. 1996-25304 filed by the present applicant. 2 is a view showing a method for manufacturing a multilayer printed circuit board disclosed in the above patent. First, as shown in FIG. 2 (a), the printed circuit pattern 12 is formed on the copper clad laminate 10 having copper foil films on both sides by ordinary photolithography, and then blackening reduction treatment is performed. do. Thereafter, as shown in FIG. 2 (b), the first photosensitive insulating resin 14 is printed on the substrate 10 having the blackening film formed thereon by a screen printing process and then semi-cured. The photosensitive insulating resin 14 is irradiated with light and developed using a mask to form a V-shaped first photovia hole 22. Subsequently, as shown in FIG. 2C, the second photosensitive insulating resin 16 is coated and developed on the first photosensitive insulating resin 14 to develop the second photovia hole 24 on the first photovia hole 22. After forming, as shown in FIG. 2 (d), the through-hole 40 for interlayer conduction is formed, and then the circuit plating layer 130 is formed by performing electroless Cu plating and electrolytic Cu plating on the insulating layer.

In the multilayer printed circuit board formed by the above-described method, as shown in the drawing, the second via hole 24 is larger than the first via hole 22 to have an overall V shape. Since it is very difficult to form the exact V-shaped via hole by controlling the sizes of the first via hole 22 and the second via hole 24 substantially, the most preferable structure is shown in FIG. The diameter d2 of 24 is about 1.05 to 2.0 times larger than the diameter d1 of the first via hole 22.

In general, in order to manufacture a high-definition, high-definition multilayer printed circuit board, an insulation resin layer having a thickness of about 50 μm or more and a via hole having a diameter of about 1 mm are required. However, in the method disclosed in the above-described patent (Application No. 1996-25304), since the insulating resin layer is applied to the screen printing method, it is impossible to apply the insulating resin layer having a thickness of about 50 μm or more, and to solve this problem, the first insulation In the case of forming a two-layered insulating resin layer composed of a resin layer and a second insulating resin layer, the components of the insulating resin may change or cause deterioration due to the complexity of the process. In addition, even when the via hole is formed, it is very difficult to form a hole having a fine diameter (about 1 mm) because the first and second via holes having different diameters must be formed.

Furthermore, when undercut occurs during development of the photosensitive insulating resin layer, since the via hole is formed with two steps, there are two undercuts, which causes a problem that the plating layer 130 is easily shorted at the undercut. .

The present invention is to solve the above problems, by forming and developing a photosensitive insulating resin layer on both sides of the copper-clad laminate by a single coating method to form a via hole to simplify the manufacturing process and to prevent degradation and breakage of the insulating resin layer An object of the present invention is to provide a method for manufacturing a multilayer printed circuit board that can be manufactured.

Another object of the present invention is to provide a method of manufacturing a multilayer printed circuit board, in which a via hole is formed in a V shape to minimize undercuts generated in the insulating resin layer, thereby improving reliability and improving yield.

In order to achieve the above object, a method of manufacturing a multilayer printed circuit board according to the present invention comprises the steps of forming a printed circuit pattern by plating and etching metal on both sides of the copper-clad laminate, and once the coating on both sides of the copper-clad laminate Coating and developing the photosensitive insulating resin layer by a method to form a via hole, forming a through hole for interlayer conduction, and then forming a Cu plating layer on an inner wall of the printed circuit pattern, the photosensitive insulating resin layer and the through hole, and Etching the Cu plating layer to form a printed circuit pattern.

Both sides of the copper-clad laminate are blackened and reduced to improve adhesion to the photosensitive insulating resin layer, and the insulating resin is applied on the laminated plate at a thickness of about 50 μm, and the via hole is developed in a V shape.

1 is a view showing a manufacturing method of a conventional multilayer printed circuit board.

2 is a view showing a manufacturing method of another conventional multilayer printed circuit board.

3 is a view showing the structure of a multilayer printed circuit board manufactured by the method of FIG.

4 is a view showing a method for manufacturing a multilayer printed circuit board according to the present invention.

Explanation of symbols on the main parts of the drawings

110: copper foil laminated plate 112: printed circuit pattern

114: photosensitive insulating resin layer 120: photo-via hole

130: Cu plated layer 140: throw hole

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

The biggest feature of the present invention is a V-shaped via hole which connects the pattern of the outer layer and the inner layer in a state in which the photosensitive insulating resin layer having a desired thickness is applied by one process unlike the prior art to minimize the change of the physical properties of the insulating resin. To form.

4 is a view showing a method of manufacturing a multilayer printed circuit board according to the present invention. As shown in FIG. 4 (a), first, metals are plated on both surfaces of the copper-clad laminate 110 having the copper thin films laminated on both sides, and the printed circuit patterns 112 are formed by etching by photolithography. As shown in FIG. 4B, the photosensitive insulating resin layer 114 is coated and developed to form a V-shaped via hole 120. At this time, although not shown in the drawing, the copper foil laminate 110 is blackened to form a blackening film to improve the adhesion between the copper foil laminate 110 and the photosensitive insulating resin layer 114.

The insulating resin layer 114 is coated to a thickness of about 50 μm by a curtain coating process, and then semi-cured through a pre-drying process. The developer acts to form the V-shaped photo-via hole 120. Predrying is carried out for about 5 to 45 minutes at a temperature of about 50 to 130 ℃, if the drying temperature is less than 50 ℃ or drying time less than 5 minutes solvent in the photosensitive insulating resin (butyl carbitol or butyl The insulating resin of cellosolve is located on the surface of the coating film, which hinders the transmission of ultraviolet rays, making it difficult to form photo-via holes due to insufficient exposure, and the surface shape of the mask is transferred or stuck due to stickiness. do.

If the drying temperature exceeds 130 ° C. or the drying time exceeds 45 minutes, the development of the via hole 120 is difficult because the development is difficult even after irradiation of the appropriate exposure amount due to the reaction of reaction radicals in the photosensitive insulating resin. Lose.

Although the photo-via hole 120 of both surfaces of the copper-clad laminate 110 is shown in FIG. 4 (b), first, the photosensitive insulating resin layer 114 is first applied to the upper surface of the copper-clad laminate 110 and the above-described process is performed. After the photo-via hole is formed, the resin layer 114 is applied to the lower surface to form the via hole.

Thereafter, as illustrated in FIG. 4C, after the through hole 140 is formed with a drill, the printed circuit pattern 112, the photosensitive insulating resin layer 114, and the through hole ( The Cu plating layer 130 is formed on the inner wall of the 140. The Cu plating layer 130 is provided with irregularities in the photosensitive resin insulating layer 114 and the photo via hole 120 to improve plating adhesion and remove smear of the inner wall of the through hole 140, and then, the inner wall of the through hole 140. It is formed by electroless Cu plating to impart conductivity to the electroless Cu plating, followed by electrolytic Cu plating having a thickness of about 15 μm.

Thereafter, as shown in FIG. 4 (d), the Cu plating layer 130 is etched by a photolithography method to form a printed circuit pattern 131.

As described above, the method for manufacturing a multilayer printed circuit board according to the present invention is simplified because the V-shaped via hole is formed after applying a photosensitive insulating resin layer having a thickness of about 50 μm by a curtin coating method. Therefore, it is possible to prevent deterioration and breakage of the insulating resin layer generated in the conventional method of applying the insulating resin layer on one side of the copper foil laminated plate in two steps. In addition, since the V-shaped photo-via hole is formed by one exposure and development, the undercut phenomenon of the insulating resin layer is minimized, and the yield of the multilayer printed circuit board is greatly improved.

Claims (8)

Forming and etching a first metal layer on at least one surface of the copper-clad laminate to form a first printed circuit pattern; Forming a photosensitive insulating layer by coating a photosensitive insulating material on the surface of the copper-clad laminate on which the first printed circuit pattern is formed once; Developing the photosensitive insulating layer to form a via hole; Forming a second metal layer on the photosensitive insulating layer and the via hole; And Etching the second metal layer to form a second printed circuit board. The method of claim 1, wherein the blackening of the copper-clad laminate is further configured. The method of claim 1, wherein the photosensitive insulating layer is formed to a thickness of 50 μm. The method of claim 1, wherein the photosensitive insulating resin is applied by a curtain coating method. The method of claim 1, wherein the forming of the second metal layer comprises: Forming irregularities in the photosensitive insulating layer and the via hole; And A method for manufacturing a multilayer printed circuit board, comprising the step of performing electrolytic Cu plating. The method of claim 1, Forming a through hole for conducting the interlayer; Removing the smear of the inner wall of the through hole; Applying electroless Cu plating to the throw hole to impart conductivity to the inner wall of the throw hole; And The electrolytic Cu plating on the inner wall of the throw hole is further configured. 7. The method of claim 6, wherein the third metal layer is formed at the same time as the second metal layer. The method of claim 1, wherein the via hole is formed in a V shape.