JP4244721B2 - Forming method of coaxial structure through hole - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a through hole having a coaxial structure related to a semiconductor device or a printed wiring circuit board.
[0002]
[Prior art]
In the conventional method, in order to form a through hole having a coaxial structure (hereinafter referred to as a conduction path), a conduction path is formed on the double-sided metal layer substrate, and a resin is poured into the hole portion of the conduction path to fill the hole. The drilling process and the conduction path are formed again. A through hole is a hole that penetrates the substrate, and then a conductive layer is formed on the inner wall of the hole. The wiring layers on the inside of the substrate and both front and back surfaces are electrically connected via the conductive layer to form a circuit. To do. The conduction path is a conductive layer on the inner wall of the hole. Hereinafter, the through hole is referred to as a conduction path.
[0003]
FIG. 5 is a side sectional view for explaining a conventional printed circuit board having a coaxial conductive path. A wiring pattern is formed on the front and back of the insulating layer 11 at the center of the substrate. A wiring pattern 19a having a conduction path is formed on the upper surface of the wiring pattern 16a having the conduction path with the insulating layer 11 interposed therebetween. The center conduction path 2 and the side conduction path 2 are through-holes having a coaxial structure, and a hole is formed by drilling twice. The wiring patterns 16a and 19a having the upper and lower conductive paths are electrically connected through the via through hole 3 to form a circuit.
[0004]
In the formation of a coaxial structure conducting path used in a conventional wired circuit board, the formation of the coaxial structure conducting path requires two holes, which increases the cost of the board because the process becomes longer. . In addition, when the position of drilling twice is shifted, there is a problem that the electrical characteristics are different from the design value and the desired performance cannot be exhibited. The proposal of the improvement is improvement in reliability in electrical characteristics (see Patent Documents 1 and 2), miniaturization of conduction paths and reduction in the number thereof (see Patent Documents 2 and 3), or improvement in adhesive strength (Patent Document 5). There are many).
[0005]
[Patent Document 1]
JP 2002-204075 [Patent Document 2]
JP 2002-204076 A [Patent Document 3]
JP 2002-64256 A [Patent Document 4]
JP 2002-204074 A [Patent Document 5]
Japanese Patent Laid-Open No. 2002-168489
[Problems to be solved by the invention]
An object of the present invention is to form a coaxial-structured conductive path used in a printed circuit board, wherein the coaxial-structured conductive path formation reduces the number of drilling operations to two holes and shortens the process. A through hole forming method is provided. Furthermore, it is a forming method that reduces the manufacturing cost of the substrate and does not shift the position of the conductive path of the coaxial structure, and the electrical characteristics are consistent with the design values and the desired performance is exhibited.
[0007]
[Means for Solving the Problems]
By forming the substrate by the following method, the number of drilling operations is reduced, and at the same time, the problem of misalignment is solved. According to a first aspect of the present invention, in the method for forming a coaxial structure through hole of a printed circuit board having a coaxial structure through hole, the coaxial structure through hole is formed using at least the following steps. How to form holes.
(A) A step of forming an electrodeposition resin layer on the entire surface including a conduction path in the metal layer of the printed circuit board in which the through hole is formed.
(B) A step of attaching an adhesive sheet to the lower surface of the printed circuit board.
(C) A step of inserting a metal ball into the through hole portion.
(D) Step of peeling the adhesive sheet (e) Step of filling the electrodeposition resin layer and the through hole with a metal layer by plating or sputtering.
(F) A step of forming a wiring pattern using a photolithography step and an etching step.
[0008]
With this method, the hole processing is only required once, and by selecting the size of the metal ball according to the hole diameter of the conduction path, the conduction path of the coaxial structure can pass through the center of the hole.
[0009]
Further, according to a second aspect of the present invention, in the method for forming a coaxial structure through hole of a printed circuit board having a coaxial structure through hole, the coaxial structure is formed using at least the following steps. Through hole formation method.
(A) A step of forming an electrodeposition resin layer on the entire surface including a conduction path in the metal layer of the printed circuit board in which the through hole is formed.
(B) A step of attaching an adhesive sheet to the lower surface of the printed circuit board.
(C) A step of inserting a metal ball into the through hole portion.
(D) Step of peeling the adhesive sheet (e) Step of filling the electrodeposition resin layer and the through hole with a metal layer by plating or sputtering.
(F) A step of forming a wiring pattern using a photolithography step and plating.
(G) A step of peeling the resist and soft-etching the thin-film metal layer other than the plated portion.
[0010]
This method is effective when the wiring pattern is miniaturized because an electrolytic plating layer is formed in the opening of the plating resist pattern.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The wiring board structure of the present invention will be described with reference to FIGS. 1 (a) to 1 (f) and FIGS. 2 (g) to (i) are methods for forming a coaxial structure through hole of the present invention.
[0012]
First, in FIG. 1A, a wiring board 20 is used in which a conductive path made of a metal layer 10 on the upper surface, a metal layer 12 on the lower surface, and an insulating layer 11 on the inner surface is formed. In FIG. 1B, an electrodeposition resin layer 13 as an insulating layer is formed on the entire surface of the metal layer by electrodeposition on the metal layer. In FIG.1 (c), after making an electrodeposition resin layer into a semi-hardened state, the adhesive sheet 14 is affixed on the lower surface of a board | substrate. Next, in the formation of the conduction path in FIG. 1 (d), the metal ball 15 is inserted into the depression in the conduction path portion, and pressure is applied to the extent that the metal ball is in contact with the electrodeposition resin layer in the depression. In FIG.1 (e), after pressurizing, the whole board | substrate is heated, while fixing a ball | bowl to the electrodeposition resin layer 13, the adhesive sheet 14 is peeled and removed. In FIG. 1 (f), electroless copper plating and electrolytic copper plating are applied to the entire substrate, and the surface of the electrodeposited resin layer and the recess of the conductive path are covered with the plated metal layer 16.
[0013]
In FIG. 2G, the etching resist pattern 17 is formed using a photolithography method. In FIG. 2 (h), the plated metal layer 16 is patterned by etching to form a wiring pattern 16a having a conduction path. In the final step, the resist on the pattern is removed. In FIG. 2I, the printed circuit board 1 having the coaxial through hole of the present invention can be formed by these steps.
[0014]
In the method for forming a through hole having a coaxial structure according to the present invention, the perforation for the conduction path is performed once and the center position of the conduction path is not shifted. In the formation process, the formation of the insulating layer by the electrodeposition method and the metal Since the ball is used, a printed circuit board having a coaxial through hole having a coaxial conductive path can be formed.
[0015]
【Example】
Hereinafter, an Example is described in detail using FIG. 1 (a)-(f) and FIG. 2 (g)-(i). 1 and 2 are manufacturing process diagrams illustrating an example of a method for forming a through hole having a coaxial structure according to the present invention.
[0016]
<Example 1>
The through hole having the coaxial structure according to the present invention was produced by the steps shown in FIGS. First, as shown in FIG. 1, through holes (large diameter 120 μm, small diameter 100 μm) are processed using a UV-YAG laser processing machine on a substrate (copper foil 9 μm, insulating layer 50 μm) having metal layers 10 and 12 on both sides. After performing, the metal layer was formed with a plating film thickness of 10 μm in the through hole and on the metal layer by the electrolytic plating method, and the substrate 20 having a conduction path was formed. (See Fig. 1 (a))
[0017]
An electrodeposition resin layer 13 of an insulating layer was formed to a thickness of 30 μm on the metal layer of the substrate 20 having a conduction path by using an electrodeposition method. After electrodeposition of the electrodeposition resin, it was in a semi-cured state by heating and drying at 120 ° C. for 30 minutes.
[0018]
Thereafter, an adhesive sheet 14 (thermal release type) was attached to the lower surface of the substrate, and a copper metal ball 15 having a diameter of 50 μm was inserted into the through hole. After the insertion, pressure was applied so that the copper ball was in contact with the electrodeposition resin layer 13 inside the hole. The adhesive sheet 14 was peeled off by heating the substrate at 130 ° C. for 30 minutes, and at the same time, the electrodeposition resin layer 13 and the copper metal balls 15 could be temporarily bonded. After peeling off the adhesive sheet, the electrodeposition resin layer 13 was further cured by heating at 160 ° C. for 1 hour to improve chemical resistance (see FIG. 1 (e)). Further, a 1 μm-thick thin metal layer was formed in the electrodeposition resin layer 13 and the through hole by electroless copper plating, and further, copper plating was performed by electrolytic copper plating so that the metal layer 16 was 10 μm or more. (See Fig. 1 (f))
[0019]
Next, a dry film resist having a thickness of 15 μm was laminated on the substrate surface, and exposure and development were performed in a photolithography process to form an etching resist pattern 17 (see FIG. 2G). Further, the metal layer other than the resist portion was removed by an etching method using ferric chloride, and the resist layer was peeled off to form the through hole having the coaxial structure of the present invention. (See Fig. 2 (i))
[0020]
<Example 2>
3 (a) to 3 (f) and FIGS. 4 (g) to (j) are manufacturing process diagrams for explaining an embodiment of a method for forming a through hole having a coaxial structure according to the present invention. This will be described in detail with reference to FIGS. The through hole having the coaxial structure according to the present invention was produced by the steps shown in FIGS. 3 (a) to 3 (f) and FIGS. 4 (g) to (j). First, as shown in FIG. 3, through holes (large diameter 120 μm, small diameter 100 μm) are processed using a UV-YAG laser processing machine on a substrate (copper foil 3 μm, insulating layer 50 μm) having metal layers 10 and 12 on both sides. After performing, the metal layer was formed with a plating film thickness of 10 μm in the through hole and on the metal layer by the electrolytic plating method, and the substrate 20 having a conduction path was formed. (See Fig. 3 (a))
[0021]
An electrodeposition resin layer 13 of an insulating layer was formed to a thickness of 30 μm on the metal layer of the substrate 20 having a conduction path by using an electrodeposition method. After electrodeposition of the electrodeposition resin, it was in a semi-cured state by heating and drying at 120 ° C. for 30 minutes. (See Fig. 3 (b))
[0022]
Thereafter, an adhesive sheet 14 (thermal release type) was attached to the lower surface of the substrate, and a copper metal ball 15 having a diameter of 50 μm was inserted into the through hole. After the insertion, pressure was applied so that the copper ball was in contact with the electrodeposition resin layer 13 inside the hole. The adhesive sheet 14 was peeled off by heating the substrate at 130 ° C. for 30 minutes, and at the same time, the electrodeposited degreased layer 13 and the copper ball were temporarily bonded. After peeling off the adhesive sheet, the electrodeposition resin layer was further cured by heating at 160 ° C. for 1 hour to improve chemical resistance. Further, a copper thin film metal layer 6 having a thickness of 0.3 μm was formed on both surfaces of the substrate by sputtering. (See Fig. 3 (f))
[0023]
Next, in FIG. 4G, a 15 μm dry film resist was laminated on the surface of the substrate, exposed and developed in a photolithography process, and a plating resist pattern 18 was formed. Next, electrolytic copper plating was used to plate the opening of the resist pattern with electrolytic copper plating to a thickness of 10 μm to form a plated metal layer 19. After stripping off the resist, the thin metal layer 6 was removed by soft etching to form a wiring pattern 19a having a conduction path. (See Fig. 4 (j))
[0024]
Through these steps, a coaxial structure through-hole of the present invention having a coaxial conductive path was formed.
[0025]
【The invention's effect】
By using the method for forming a coaxial structure through hole according to the present invention, the coaxial structure through hole could be formed by a simple process. According to the method for forming a through hole having a coaxial structure according to the present invention, the number of drilling steps is reduced, so that the delivery time of the substrate can be shortened and the cost is reduced. Further, by inserting the metal ball into the circular conduction path, the center of the conduction path is not shifted by the position shift correction function by self-alignment, so that the electrical characteristics are more stable.
[Brief description of the drawings]
FIGS. 1A to 1F are manufacturing process diagrams for explaining an example of a method for forming a through hole having a coaxial structure according to the present invention, wherein FIGS.
FIGS. 2A and 2B are manufacturing process diagrams for explaining an example of a method for forming a through hole having a coaxial structure according to the present invention, wherein FIGS.
FIGS. 3A to 3F are manufacturing process diagrams for explaining an embodiment of a method for forming a through hole having a coaxial structure according to the present invention, wherein FIGS.
FIG. 4 is a manufacturing process diagram for explaining one embodiment of a method for forming a through hole having a coaxial structure according to the present invention, wherein (g) to (j) are side cross sections.
FIG. 5 is a side sectional view of a printed circuit board having a conductive path of a conventional coaxial structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wiring circuit board which has a conduction path 2 ... Conduction path (through hole)
DESCRIPTION OF SYMBOLS 3 ... Via-through hole 6 ... Thin film metal layer 10 ... Metal layer 11 ... Insulating layer 12 ... Metal layer 13 ... Electrodeposition resin layer 14 (of insulating layer) ... Adhesive sheet 15 ... Metal ball 16 ... Plating metal layer 16a ... Conducting path Wiring pattern 17 having etching pattern 18 plating resist pattern 19 plating metal layer 19a wiring pattern 20 having a conductive path base substrate

Claims (2)

A method of forming a coaxial structure through hole in a method of forming a coaxial structure through hole of a printed circuit board having a coaxial structure through hole, using at least the following steps.
(A) A step of forming an electrodeposition resin layer on the entire surface including a conduction path in the metal layer of the printed circuit board in which the through hole is formed.
(B) A step of attaching an adhesive sheet to the lower surface of the printed circuit board.
(C) A step of inserting a metal ball into the through hole portion.
(D) Step of peeling the adhesive sheet (e) Step of filling the electrodeposition resin layer and the through hole with a metal layer by plating or sputtering.
(F) A step of forming a wiring pattern using a photolithography step and an etching step. A method of forming a coaxial structure through hole in a method of forming a coaxial structure through hole of a printed circuit board having a coaxial structure through hole, using at least the following steps.
(A) A step of forming an electrodeposition resin layer on the entire surface including a conduction path in the metal layer of the printed circuit board in which the through hole is formed.
(B) A step of attaching an adhesive sheet to the lower surface of the printed circuit board.
(C) A step of inserting a metal ball into the through hole portion.
(D) Step of peeling the adhesive sheet (e) Step of filling the electrodeposition resin layer and the through hole with a metal layer by plating or sputtering.
(F) A step of forming a wiring pattern using a photolithography step and plating.
(G) A step of peeling the resist and soft-etching the thin-film metal layer other than the plated portion.

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