JPH06326462A - Manufacture printed wiring board provided with through-hole - Google Patents

Abstract

PURPOSE:To realize a printed wiring board provided with through-holes which can be connected together by a method wherein a plating layer formed on the inner wall of the through-hole is split into pieces by an insulator. CONSTITUTION:A copper foil 3 is pasted on both the sides of an insulating layer 2 for the formation of a copper-plated laminate board, through-holes are provided to the laminate board 1 partially overlapping each other to form a primary hole (through-hole) 4, a copper plating layer is formed on the inner wall of the primary hole 4 and the surface of the copper foil 3 through electroless copper plating, and furthermore a copper plating layer 5 is formed on the upside of the copper plating layer. The copper plating layer 5 is formed uniform in thickness, a photosensitive etching resist, film 6 is laminated thereon, exposed to light, and developed, and the unexposed and undeveloped film 6 is removed, and the disused copper plating layer 5 and the disused copper foil 3 are removed. Therefore, the film 6 left unremoved on a circuit pattern is separated off, and the edge of the overlap of the primary hole 4 where through-holes overlap each other is cut off through a secondary hole processing, whereby four insulating sections 9 are formed, and four circuit patterns P on each side of the laminate board 1 are connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board having through holes, and in particular, in a double-sided printed wiring board, a plurality of circuit patterns formed on the upper surface of the printed wiring board and a plurality of circuit patterns formed on the lower surface. Each of the plurality of formed circuit patterns is independent of each other, and in the case of the multilayer printed wiring board, the circuit patterns on the upper and lower surfaces and between the circuit patterns on the upper and lower surfaces and the circuit pattern on the intermediate layer are respectively independent. The present invention relates to a method for manufacturing a printed wiring board having through holes that can be connected to each other independently.

[0002]

2. Description of the Related Art Conventionally, various printed wiring boards having through holes have been proposed. In such printed wiring boards, through holes are generally formed on both upper and lower surfaces of a double-sided printed wiring board. It is used as a means to connect circuit patterns to each other.In a multilayer printed wiring board, circuit patterns on the upper and lower surfaces are connected to each other, and circuit patterns on the upper and lower surfaces and circuit patterns on the intermediate layer are mutually connected. It is used as a means of connecting. Then, in each of the printed wiring boards, two circuit patterns formed in different layers are connected to each other by one through hole.

However, if the number of circuit patterns connectable via one through hole is limited to two as described above, when a large number of circuit patterns are present on the wiring board, the circuit patterns are connected to each other. Therefore, it is necessary to form many through holes in the wiring board. In this case, in designing the circuit pattern, it is preferable to form a plurality of through holes collectively on the wiring board, but since the land patterns are usually formed around the through holes, the land patterns are included. A region where the circuit pattern cannot be formed inevitably occurs around the portion where the through hole is formed. The area of such a region becomes larger as the circuit pattern becomes more complicated and the number of through-holes increases, and the occupancy rate on the wiring board increases, so that a problem still remains in the wiring of the circuit pattern. .

In order to solve such a problem, in recent years, a function of forming an insulating portion in order to divide the conductor plating formed on the inner peripheral wall of the through hole into a plurality of parts and connecting a large number of circuit patterns to one through hole. Have been developed. For example, in Japanese Utility Model Application Laid-Open No. 4-120262, a plurality of divided plated portions are formed by providing clearance portions (insulating portions) in via holes (through holes), and printed wiring boards of the printed circuit board are provided through the plated portions. A printed circuit board is described in which a plurality of circuit patterns formed on both upper and lower surfaces are connected to each other. Then, as a method of forming the clearance portion in the via hole, a method of coating a material capable of preventing the formation of a plating layer when plating the via hole, and plating the entire inner surface of the via hole After applying, a method of irradiating a laser beam or the like to remove the plating layer is adopted.

[0005]

However, in the former method described in Japanese Utility Model Laid-Open No. 4-120262, it is not possible to apply a material such as a plating resist on the inner surface of the via hole according to the width corresponding to the clearance. It is extremely difficult, and it is only an extremely unrealistic method in the present situation where the circuit pattern becomes more complicated and the diameter of the via hole becomes smaller.

In the latter method described above, it is considered possible to melt and remove the plating layer formed on the inner surface of the via hole with a laser beam, but the irradiation control of the laser beam becomes extremely complicated. As a result, there is a possibility that the cost of the wiring board may be increased.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The plating layer formed on the inner peripheral wall of the through hole is insulated by a very simple method to divide the plating layer into a plurality of layers. Thus, in the double-sided printed wiring board, the plurality of circuit patterns formed on the upper surface of the printed wiring board and the plurality of circuit patterns formed on the lower surface of the printed wiring board are separately and independently provided, and also in the multilayer printed wiring board. Another object of the present invention is to provide a method of manufacturing a printed wiring board having through-holes that can be connected to each other independently between the upper and lower circuit patterns and between the upper and lower circuit patterns and the intermediate circuit pattern. And

[0008]

In order to achieve the above object, the invention according to claim 1 is a through-hole forming step of forming a through hole by overlapping a part of a plurality of through holes in a wiring board body. A plating step of forming a plating layer of a metal conductor on the inner peripheral wall of the through hole; and a circuit pattern forming step of forming circuit patterns connected to each other through the plating layer of the through hole on both surfaces of the wiring board body. And a removing step of removing an edge portion of the lap portion between the through holes in the through hole.

According to a second aspect of the present invention, there is provided a through hole forming step of forming a through hole by overlapping a part of a plurality of through holes on a wiring board main body, and a wiring board main body having the through hole formed therein. A plating catalyst applying step of applying an electroless plating catalyst to the through hole, and a removing step of removing the electroless plating catalyst present at the edge by removing the edge of the lap portion of each through hole in the through hole, Except for the edges where the electroless plating catalyst has been removed, a plating layer of metal conductor is formed on the inner peripheral wall of the through hole by electroless plating, and circuit patterns connected to each other through the plating layer of the through hole are formed. The electroless plating process is performed on both surfaces of the wiring board body.

Further, the invention according to claim 3 is a through hole forming step of forming a through hole by overlapping a part of a plurality of through holes in a wiring board main body, and a metal conductor on an inner peripheral wall of the through hole. A plating step of forming a plating layer, a circuit pattern forming step of forming a plurality of circuit patterns connected to each other through the plating layer of the through hole on both surfaces of the wiring board body, and filling the inside of the through hole. While laminating prepregs on both sides of the wiring board main body, a multi-layering step of sticking copper foil on both sides of the laminated prepregs, and a removing step of removing edges of lap portions between the through holes in the through holes. It is composed of.

[0011]

In the invention of claim 1 having the above-mentioned structure, first,
A through hole is formed by overlapping a part of the plurality of through holes with the wiring board body. Thereafter, a plating layer of a metal conductor is formed on the inner peripheral wall of the through hole, and a plurality of circuit patterns connected to the plating layer of the through hole are formed on both surfaces of the wiring board body. Then, the edge portion of the lap portion between the through holes in the through hole is removed, whereby the printed wiring board having the through hole is manufactured. At this time, in the through hole, the insulating portion is formed by removing the edge portion of the plating layer, so that the plating layer in the through hole is divided into a plurality of parts. As a result, the plurality of circuit patterns formed on both sides of the wiring board body are connected to each other through the plurality of plating layers divided in the through holes.

According to the second aspect of the invention, after the through holes are formed in the wiring board main body by partially overlapping the plurality of through holes, the electroless plating catalyst is applied to the inside of the through holes and the wiring board main body. To be done. Next, the edge portions of the lap portions of the through holes in the through holes are removed to remove the electroless plating catalyst present at the edge portions. At this time, in the through hole, the portion where the electroless plating catalyst is present is discontinuously formed through the edge portion where the electroless plating catalyst is removed. Thereafter, by electroless plating, a plating layer of a metal conductor is formed on the inner peripheral wall of the through hole except for the edge portion where the electroless plating catalyst is removed as described above. In this state, the plating layer is not formed on the edge where the electroless plating catalyst is removed, but the plating layer is selectively formed on the portion where the electroless plating catalyst exists discontinuously in the through hole. Therefore, a plurality of plating layers are present in the through hole with the edge portion where the plating layer is not formed as an insulating portion. And
At the same time, a plurality of circuit patterns connected to each other through the plurality of plating layers formed in the through holes are formed on both surfaces of the wiring board body.

Further, in the third aspect of the present invention, first, the through hole is formed in the wiring board main body by partially overlapping the plurality of through holes. Thereafter, a plating layer of a metal conductor is formed on the inner peripheral wall of the through hole, and a plurality of circuit patterns connected to the plating layer of the through hole are formed on both surfaces of the wiring board body. Then, the prepreg is laminated on both surfaces of the wiring board main body while filling the inside of the through hole, and the copper foil is attached to both surfaces of the laminated prepreg. As a result, the printed wiring board is multilayered. Furthermore, after this, the edges of the lap portions between the through holes in the through holes are removed, whereby a printed wiring board having through holes is manufactured. When removing the edge portion of the lap portion in this way, since the resin of the prepreg is filled in the through hole in the multi-layering step, it is not necessary to separately perform the step of filling the resin in the through hole, and It is possible to remove the edge portion of the wrap portion without peeling the plating layer of the metal conductor or burrs at the edge portion of the wrap portion. Through each of the above steps, the insulating portion is formed by removing the edge portion of the plating layer in the through hole, and thus the plating layer in the through hole is divided into a plurality of parts. As a result, the plurality of circuit patterns formed on both sides of the wiring board main body and the circuit pattern of the intermediate layer formed by layering these circuit patterns are separated from each other by a plurality of platings divided in the through holes. They are connected to each other through layers.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A detailed description will be given below of an embodiment embodying the present invention with reference to the drawings. First, a manufacturing method according to the first embodiment will be described with reference to FIGS. FIG. 1 is a process diagram showing a method for manufacturing a printed wiring board based on the subtractive method according to the first embodiment. First, as shown in step (a), a double-sided copper-clad laminate 1 cut into predetermined dimensions is prepared. To do. The double-sided copper-clad laminate 1 is formed by laminating copper foils 3 on the upper and lower surfaces of an insulating layer 2 as is well known.

Next, in step (b), primary holes (through holes) 4 are formed in the copper-clad laminate 1 while partially wrapping a plurality of through holes. The primary hole processing will be described with reference to FIG. FIG. 2 is a plan view showing the primary holes 4 formed in the copper-clad laminate 1 by the primary hole processing. The primary holes 4 are, as shown in FIG. Four circular holes C1, C2, C3, C4 are formed in the copper-clad laminate 1 so that the peripheries of the holes C1, C2, C3, C4 are in contact with each other, and thereafter, the circular holes C1, C2, C3,
It is formed by forming a circular hole C5 at the center of C4. Subsequently, in step (c), after the surface of the primary hole 4 is cleaned and the inner wall of the hole is cleaned, the primary hole 4 is electroless copper plated.
A copper plating layer is formed on the inner peripheral wall and the upper surface of each copper foil 3. Then, a copper plating layer 5 is further formed on the upper surface of the copper plating layer formed by electroless plating through electrolytic copper plating, and the thickness of the copper plating layer 5 in the primary hole 4 and the copper foil 3 are formed. The thickness of the formed copper plating layer 5 is made uniform. This state is shown in step (C).

Further, in the step (d), a photosensitive etching resist film 6 is laminated on each copper plating layer 5 formed on both surfaces of the copper-clad laminate 1. After this,
In the step (e), the etching resist film 6 is exposed and developed according to a predetermined circuit pattern, and the etching resist film 6 which is not exposed and developed is removed. At this point, as shown in the step (e), the etching resist film 6 is formed on the upper surface of the copper plating layer 5 to be left as a circuit pattern on the copper plating layer 5 formed on both surfaces of the copper-clad laminate 1. It is left.

Next, in the step (f), an etching treatment is performed to remove the copper plating layer 5 and the copper foil 3 which are unnecessary as a circuit pattern, and further, in the step (g), the copper-clad laminate is as described above. The etching resist film 6 remaining on the circuit patterns formed on both sides of 1 is peeled off. As a result, a predetermined circuit pattern is formed on both surfaces of the copper-clad laminate 1, and the circuit patterns are connected to each other via the copper plating layer 5 formed on the inner peripheral wall of the primary hole 4. The wiring board PWB is obtained.

Then, in the printed wiring board PWB manufactured as described above, in the step (h), a secondary hole processing is carried out so as to cut the edges of the lap portions which are mutually wrapped by the primary holes 4. The secondary hole processing will be described with reference to FIG. Fig. 3 shows a printed wiring board PW with secondary holes.
It is a plan view showing a secondary hole formed in B, and the secondary hole processing is performed by drilling each lap portion L between the primary holes 4 formed as described above (a drill used for the primary hole processing). The secondary hole (through hole) 7 is formed by forming a circular hole C6 to be cut off through the lap portion L having a larger diameter than that). When performing the secondary hole machining in this way, 1
It is desirable to form a circular hole C6 with a drill after filling the inside of the next hole 4 with a conductive material such as insulating resin or solder. By doing this, when forming the circular hole C6,
It is possible to reliably prevent the copper plating layer 5 formed on the inner peripheral wall of the secondary hole 7 from being peeled off from the inner peripheral wall and from causing burrs or the like.

FIG. 4 shows a printed wiring board PWB manufactured through the above steps (a) to (h).
It will be explained based on. FIG. 4 is a perspective view of the printed wiring board PWB schematically showing a part of the secondary holes 7 in the printed wiring board PWB by cutting it out. In the copper plating layer 5, four insulating portions 9 (only one insulating portion 9 is shown in FIG. 4) are obtained by cutting the lap portion L by the secondary hole processing performed in the step (h). Formed, and as a result, the secondary hole 7
The copper plating layer 5 on the inner peripheral wall of is divided into four parts. In addition, on both upper and lower sides of the printed wiring board PWB,
Four circuit patterns P each having a land portion 8 are formed (in FIG. 4, only two circuit patterns P are shown on the upper surface, and four circuit patterns P are similarly formed on the back surface). Each of the upper and lower two circuit patterns P has the copper plating layer 5 divided as described above.
Are connected to each other via.

As a result, four conduction paths (copper plated layer 5) can be provided in one secondary hole 7 (through hole) formed in the printed wiring board PWB. As a result, 1
Since the upper and lower four circuit patterns P in the printed wiring board PWB can be connected to each other through the two secondary holes 7, the number of through holes to be formed in the printed wiring board PWB is reduced as a whole, and the through holes are printed wiring. The occupied area of the plate PWB can be made extremely small.

Next, a method of manufacturing a printed wiring board according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a process diagram showing a method for manufacturing a printed wiring board based on the additive method according to the second embodiment. First, in step (A), a predetermined circuit pattern Q1 is formed on both upper and lower surfaces.
Three-layer laminated plate 1 in which insulating layers 11B are further laminated on both sides of the insulating layer 11A on which (the inner layer circuit pattern) is formed.
Prepare 0. At this point, no copper foil is present on both sides of the three-layer laminate 10.

Next, in step (B), an adhesive layer 12 for electroless plating is applied and formed on both surfaces of the three-layer laminate 10. After that, in step (C), primary hole processing for through holes is performed. This primary hole processing is the same as the processing performed in the step (b) in the first embodiment (see FIG. 2). That is, each circular hole C through the drill
Four circular holes C1, C2, C3, C4 are formed in the three-layer laminate 10 so that the peripheries of 1, C2, C3, C4 are in contact with each other, and thereafter, the circular holes C1, C2, C3, C4 are This is done by forming a circular hole C5 in the center. The primary hole 13 is formed by this primary hole processing. Further, after the primary holes 13 are formed in this manner, electroless plating catalyst nuclei made of palladium are applied to both surfaces of the three-layer laminate 10 and the inner peripheral wall of the primary holes 13.

Subsequently, in step (D), a photosensitive plating resist film is laminated on both surfaces of the three-layer laminate 10, and the plating resist film is exposed and developed according to the shape of a predetermined circuit pattern. After that, the plating resist film in the portion where the circuit pattern is formed is peeled and removed. As a result, the plating resist 1 is formed on both surfaces of the laminated plate 10 at the portions not involved in the formation of the circuit pattern.
4 is obtained.

Further, in the step (E), secondary hole processing is carried out to cut off the edges of the lap portions which overlap each other with the primary holes 13 formed as described above. The secondary hole machining is the same as the machining performed in the first embodiment (see FIG. 3), that is, the lap portions L between the primary holes 13 are drilled (used for the primary hole machining). A hole having a diameter larger than that of the drill to be cut) is formed to form a circular hole C6 for cutting, thereby forming a secondary hole (through hole) 15 formed by cutting the lap portion L. Is. At this point, the secondary hole 15
The plating catalyst nucleus added in the step (C) does not exist in the portion where the lap portion L is cut off as described above (it becomes an insulating portion as described later). After that, the laminated plate 10
The activation treatment of the plating catalyst nuclei provided on both sides of the inner peripheral wall of the secondary hole 15 is performed.

Then, in step (F), copper electroless plating is performed. As a result, a predetermined circuit pattern Q2 is formed on the portion of the laminated plate 10 not covered by the plating resist, and the plating layer 16 is formed on the portion of the secondary hole 15 which is not cut during the secondary hole processing. Is formed. As a result, each circuit pattern Q2 formed on the upper and lower surfaces of the laminated plate 10 is connected to the plating layer 16 on the inner peripheral wall of the secondary hole 15, and is formed inside the laminated plate 10 via the plating layer 16. The laminated printed wiring board PWB connected with the circuit pattern Q1 that is formed is manufactured.

The laminated printed wiring board PWB manufactured through the steps (A) to (F) will be described with reference to FIG. FIG. 6 is a perspective view of the printed wiring board PWB schematically showing a cutout of a part of the secondary hole 15 in the laminated printed wiring board PWB. The printed wiring board PWB is formed on the inner peripheral wall of the secondary hole 15 in the step (F). The copper plating layer 16 thus formed includes
The lap portion L is formed by the secondary hole processing performed in the step (E).
By cutting out and providing a portion to which the plating catalyst nucleus is not provided, four insulating portions 17 (only one insulating portion 17 is shown in FIG. 6) are formed, and as a result, the secondary holes 15 The copper plating layer 16 on the inner peripheral wall is divided into four parts. Further, four circuit patterns Q2 each having a land portion 18 are formed on both upper and lower surfaces of the printed wiring board PWB (in FIG. 6, only two circuit patterns Q2 are shown on the upper surface, and the back surface is also shown). Similarly, four circuit patterns Q2 are formed), two circuit patterns Q2 on the upper and lower sides, and a circuit pattern Q1 formed inside the laminated plate 10 are the copper divided as described above. The plating layers 16 are connected to each other.

In such a laminated printed wiring board PWB, the secondary hole processing is performed before the copper plating layer 16 is formed on the inner peripheral wall of the secondary hole (through hole) 15. Unlike the manufacturing method of, the secondary hole 15
Even when the secondary hole processing is performed without filling the inside with resin or the like, peeling or burrs of the circuit pattern Q1 occurs when the copper plating layer 16 formed on the inner peripheral wall of the secondary hole 15 is divided. Can be reliably prevented.

As described above, according to the method for manufacturing a laminated printed wiring board according to the second embodiment, four conduction paths (in one secondary hole 15 (through hole) formed in the laminated printed wiring board PWB ( Since the copper plating layer 16) can be provided, and as a result, the upper and lower four circuit patterns Q2 in the printed wiring board PWB can be connected to each other through one secondary hole 15, the through wirings to be formed in the printed wiring board PWB. By reducing the number of holes as a whole, the area occupied by the through holes in the printed wiring board PWB can be made extremely small. In particular, each of the four copper plating layers 16 is divided into two parts, the circuit pattern Q2 on both sides of the laminated printed wiring board PWB and the circuit pattern Q1 formed inside the laminated board 10, and the laminated board 10. Since the circuit patterns Q1 formed inside can be connected to each other, by increasing the number of layers in the laminated printed wiring board PWB by one layer, the area in which a circuit can be formed can be substantially increased. In other words, if the wiring density is the same, the number of wiring layers can be reduced by adopting the method of the second embodiment.

Next, a method of manufacturing a printed wiring board according to the third embodiment of the present invention will be described with reference to FIGS. 7 and 8 are process diagrams showing a method for manufacturing a multilayer printed wiring board according to the third embodiment. This manufacturing method is basically the same as the manufacturing method of the printed wiring board in the first embodiment, and in the manufacturing method of the multilayer printed wiring board of the third embodiment, a multi-layering process and a multi-layering process are involved. It is different from the manufacturing method of the first embodiment in that the step of forming a circuit pattern is further performed through the through hole. 7 and 8, first, as shown in step (1), a double-sided copper-clad laminate 21 cut into a predetermined size is prepared. The double-sided copper-clad laminate 21 has the insulating layer 2 as is well known.
The copper foil 23 is attached to both upper and lower surfaces of the sheet 2.

Next, in step (2), primary holes (through holes) 24 are formed in the copper-clad laminate 21 while partially wrapping the plurality of through holes. This primary hole machining is the same as the machining performed in the step (b) in the first embodiment (see FIG. 2). That is, four circular holes C1, C2, C3, C4 are formed in the double-sided copper-clad laminate 21 through a drill so that the peripheries of the circular holes C1, C2, C3, C4 are in contact with each other. Circular holes C1, C
This is done by forming a circular hole C5 in the center of 2, C3, C4. The primary hole 24 is formed by this primary hole processing.

Subsequently, in step (3), after the surface of the primary hole 24 is cleaned and the inner wall of the hole is cleaned, the inner peripheral wall of the primary hole 24 and the upper surface of each copper foil 23 are subjected to electroless copper plating. A copper plating layer is formed on. Further, a copper plating layer 25 is formed on the upper surface of the copper plating layer formed by electroless plating through electrolytic copper plating, and the thickness of the copper plating layer 25 in the primary holes 24 and the copper foil 23 are formed. Copper plating layer 25
To make the thickness uniform. This state is shown in step (3).

Further, in step (4), a photosensitive etching resist film 26 is laminated on each copper plating layer 25 formed on both surfaces of the copper-clad laminate 1. After that, in step (5), the etching resist film 26 is exposed and developed according to a predetermined circuit pattern,
The undeveloped etching resist film 26 is removed. At this point, an etching resist film 26 is formed on the upper surface of the copper plating layer 25 to be left as a circuit pattern on the copper plating layer 25 formed on both surfaces of the copper-clad laminate 21 as shown in step (5). It is left.

Next, in step (6), an etching treatment is performed to remove the copper plating layer 25 and the copper foil 23 which are unnecessary as a circuit pattern, and further, in step (7), the copper-clad laminate is as described above. The etching resist film 26 remaining on the circuit patterns formed on both surfaces of 21 is peeled off. As a result, a predetermined circuit pattern is formed on both surfaces of the copper-clad laminate 21, and each circuit pattern has 1
The printed wiring board PWB mutually connected through the copper plating layer 25 formed on the inner peripheral wall of the next hole 24 is obtained.

In the subsequent step (8), the printed wiring board PWB obtained as described above is multilayered. In the multi-layering process, the prepreg R is laminated on both surfaces of the printed wiring board PWB while filling the inside of the primary hole 24 formed as described above, and then the copper foil 30 is attached to both surfaces of the prepreg R. . As a result, the primary hole 24
A multilayer printed wiring board ML-PWB in which the resin of the prepreg R is filled is obtained. Further, in step (9), through holes H are drilled at predetermined positions of the multilayer printed wiring board ML-PWB via a drill, and further, in step (10), through holes are formed in the same manner as in step (3) above. Hall H
After cleaning the inner surface of the hole and the inner wall of the hole, a copper plating layer is formed on the inner peripheral wall of the through hole H and the upper surface of each copper foil 30 by electroless copper plating. Further, a copper plating layer 31 is formed on the upper surface of the copper plating layer formed by electroless plating through electrolytic copper plating, and the thickness of the copper plating layer 31 in the through hole H and the copper foil 30 are formed. The thickness of the copper plating layer 31 is made uniform. This state is the process (1
0).

After the step (10) is completed, the step (11)
By performing the same steps as the above steps (4) to (7), a predetermined circuit pattern P is formed on the upper and lower surfaces of the multilayer printed wiring board ML-PWB via the copper plating layers 31.
1 (see FIG. 9) is formed. In addition, from the copper plating layers 25 formed on both surfaces of the insulating layer 22 existing inside the multilayer printed wiring board ML-PWB, the intermediate layer circuit pattern P is formed.
2 (see FIG. 9) are formed.

Then, the multilayer printed wiring board ML-PWB manufactured as described above has 1
Secondary hole processing is performed in order to cut the edges of the wrap portions that wrap each other at the next hole 24. The secondary hole machining is the same as the machining performed in the first embodiment (see FIG. 3), that is, each lap L of the primary holes 24 is drilled (used for the primary hole machining). Formed by forming a circular hole C6 for cutting through a hole having a diameter larger than that of the drill to be formed, thereby forming a secondary hole (through hole) 27 formed by cutting the lap portion L. Is.

When the secondary hole is formed as described above, the prepreg R is formed inside the primary hole 24 in the multilayering step (8).
Since it is filled with the resin of No. 1, there is no need to perform another step for filling the resin or the like into the primary hole 24, and the resin of the prepreg R filled in the primary hole 24 is used. It is possible to reliably prevent burrs from being formed on the inner peripheral wall of the secondary hole 27 and to prevent the copper plating layer 25 from peeling off from the inner peripheral wall of the secondary hole 27.

A multilayer printed wiring board ML-PWB manufactured by going through the above steps (1) to (12)
Will be described with reference to FIG. FIG. 9 is a perspective view of the multilayer printed wiring board ML-PWB which schematically shows a part of the secondary hole 27 in the multilayer printed wiring board ML-PWB by cutting it out. 3)
The copper plating layer 25 formed in
By cutting the lap portion L by the secondary hole processing performed in step 4, four insulating parts 29 (only one insulating part 29 is shown in FIG. 9) are formed, and as a result, the secondary holes 27 are formed. The copper plating layer 25 will be divided into four parts. Therefore, the copper plating layer 25 facing the inner peripheral wall of the secondary hole 27
The intermediate layer circuit pattern P2 according to (4) is insulated from each other at each of the four positions of the secondary hole 27 via each insulating portion 29. Circuit patterns P1 are formed on the upper and lower surfaces of the multilayer printed wiring board ML-PWB, and the circuit patterns P1 are connected to each other through through holes H.

As a result, the multilayer printed wiring board ML-P
Four conduction paths (copper plating layer 25) can be provided in one secondary hole 27 (through hole) formed in WB, and as a result, the multilayer printed wiring board ML is provided through one secondary hole 27. -In the intermediate layer of the PWB, the upper and lower four intermediate layer circuit patterns P2 can be connected to each other, so that the number of through holes to be formed in the multilayer printed wiring board ML-PWB is reduced and the through holes are provided in the multilayer printed wiring. The occupied area of the plate PWB can be made extremely small.

As described in detail above, according to the manufacturing method of the first embodiment, the double-sided copper-clad laminate 1 is formed with the primary holes 4 while partially lapping the four through holes.
The copper plating layer 5 is formed on the inner peripheral wall of the primary hole 4, and thereafter, the lap portion L in the primary hole 4 is cut off to form the secondary hole 7 to form four copper plating layers 5 on the copper plating layer 5. Insulation part 9
Since the copper plating layer 5 is divided into four parts by forming, the upper and lower four circuit patterns P in the printed wiring board PWB can be connected to each other through the divided copper plating layers 5. The number of through holes to be formed in the printed wiring board PWB can be reduced as a whole, and the area occupied by the through holes in the printed wiring board PWB can be made extremely small.

Further, in the manufacturing method of the second embodiment, the primary holes 13 are formed in the three-layer laminated plate 10 having the circuit pattern Q1 formed therein while partially overlapping the four through holes. After that, the electroless plating catalyst nucleus is applied to the inner peripheral wall of the primary hole 13, and the lap portion L in the primary hole 13 is cut off to form the secondary hole 15.
Four insulating parts 1 without plating catalyst nuclei in the next hole 15
7 is provided, and thereafter, the copper plating layer 16 is formed on the inner peripheral wall of the secondary hole 15 by electroless plating. Therefore, one secondary hole 15 formed in the laminated printed wiring board PWB is formed.
Four conduction paths (copper plating layer 16) in the (through hole)
As a result, the upper and lower four circuit patterns Q2 in the printed wiring board PWB can be connected to each other through one secondary hole 15, so that the printed wiring board PW can be formed.
The number of through holes to be formed in B can be reduced as a whole, and the area occupied by the through holes in the printed wiring board PWB can be made extremely small. In particular, each of the four copper plating layers 16 is divided into two parts, the circuit pattern Q2 on both sides of the laminated printed wiring board PWB and the circuit pattern Q1 formed inside the laminated board 10, and the laminated board 10. Since the circuit patterns Q1 formed inside can be connected to each other, by increasing the number of layers in the laminated printed wiring board PWB by one layer, the area in which a circuit can be formed can be substantially increased. In other words, if the wiring density is the same, the number of wiring layers can be reduced by adopting the method of the second embodiment.

Further, in the manufacturing method of the third embodiment, the primary holes 24 are formed in the double-sided copper-clad laminate 21 while partially overlapping the four through holes, and the primary holes 2 are formed.
Copper plating layer 25 is formed on the inner peripheral wall of
4, the prepreg R is laminated on both sides of the double-sided copper-clad laminate 21 while filling the inside, and the copper foil 30 is attached to both sides of the prepreg R to form the multilayer printed wiring board ML-PWB. The copper plating layer 25 is formed by cutting the lap portion L in 24 to form the secondary hole 27.
Since the four insulating portions 29 are formed on each of the copper plating layers 25 so as to divide the copper plating layer 25 into four, each of the divided copper plating layers 25 is divided.
In the intermediate layer of the multilayer printed wiring board ML-PWB, upper and lower four intermediate layer circuit patterns P2 can be connected to each other, and thus the total number of through holes to be formed in the multilayer printed wiring board ML-PWB can be reduced. The area occupied by the through holes in the multilayer printed wiring board ML-PWB can be made extremely small by reducing

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various improvements and modifications can be made without departing from the gist of the present invention. For example, in each of the embodiments described above, basically four circular holes C1, C2, C3, and C4 are provided when forming the primary holes 4 and 13, but the number of circular holes is not limited to four. It is obvious that the same effect as described above can be obtained even if the number is two, three, or five or more.

[0044]

As described above, according to the present invention, the plating layer formed on the inner peripheral wall of the through hole is insulated by a very simple method and the plating layer is divided into a plurality of layers. A plurality of circuit patterns formed on the upper surface of the printed wiring board and a plurality of circuit patterns formed on the lower surface are separately and independently used. It is possible to provide a method for manufacturing a printed wiring board having through holes that can be connected to each other independently and independently between the circuit patterns on both surfaces and the circuit pattern on the intermediate layer, and the industrial effect thereof is great. .

[Brief description of drawings]

FIG. 1 is a process drawing showing the method of manufacturing a printed wiring board based on the subtractive method according to the first embodiment.

[FIG. 2] 1 formed on a copper-clad laminate by primary hole processing
It is a top view showing the next hole.

FIG. 3 is a plan view showing secondary holes formed in a printed wiring board by secondary hole processing.

FIG. 4 is a perspective view of a printed wiring board schematically showing a part of a secondary hole in the printed wiring board by cutting out.

FIG. 5 is a process drawing showing the method of manufacturing a printed wiring board based on the additive method according to the second embodiment.

FIG. 6 is a perspective view of a printed wiring board schematically showing a cutout of a part of a secondary hole in the laminated printed wiring board.

FIG. 7 is a process drawing showing the method of manufacturing a multilayer printed wiring board according to the third embodiment.

FIG. 8 is a process drawing showing the method of manufacturing the multilayer printed wiring board according to the third example.

FIG. 9 is a perspective view of a multilayer printed wiring board schematically showing a part of a secondary hole in the multilayer printed wiring board by cutting out.

[Explanation of symbols]

1 ... Double-sided copper-clad laminate, 2 ... insulating layer, 3 ...
Copper foil, 4 ... Primary hole, 5 ... Copper plating layer, 7 ...
Secondary hole, 9 ... Insulating part, 10 ... Three-layer laminated plate, 13
... primary hole, 15 ... secondary hole, 16 ... copper plating layer, 17 ... insulating part, 21 ... double-sided copper-clad laminate,
22 ... Insulating layer, 23 ... Copper foil, 24 ... Primary hole, 25 ... Copper plating layer, 27 ... Secondary hole, 29.
..Insulation part, 30 .... Copper foil, 31 ... Copper plating layer, C
1, C2, C3, C4, C5, C6 ... Circular hole, L
..Wrap portion, P, P1, P2, Q1, Q2 ... Circuit pattern, PWB ... Printed wiring board, ML-PWB
... Multilayer printed wiring board, R ... Prepreg

Claims (3)

[Claims] 1. A through hole forming step of forming a through hole by overlapping a part of a plurality of through holes on a wiring board main body, and a plating step of forming a plating layer of a metal conductor on an inner peripheral wall of the through hole. A circuit pattern forming step of forming a plurality of circuit patterns connected to each other through a plated layer of the through hole on both surfaces of the wiring board main body, and an edge portion of a wrap portion of each through hole in the through hole. A method of manufacturing a printed wiring board having a through hole, which comprises a removing step of removing the through hole. 2. A through hole forming step of forming a through hole by wrapping a part of a plurality of through holes in a wiring board main body, and applying an electroless plating catalyst to the wiring board main body in which the through hole is formed. A plating catalyst application step, a removal step of removing the electroless plating catalyst existing at the edge by removing the edge of the lap portion of each through hole in the through hole, and the electroless plating catalyst was removed A plating layer of a metal conductor is formed on the inner peripheral wall of the through hole by electroless plating except for the edges, and a plurality of circuit patterns connected to each other through the plating layer of the through hole are formed on both sides of the wiring board body. A method for manufacturing a printed wiring board having a through hole, which comprises a step of forming an electroless plating layer. 3. A through hole forming step of forming a through hole by wrapping a part of a plurality of through holes in a wiring board body, and a plating step of forming a plating layer of a metal conductor on an inner peripheral wall of the through hole. A circuit pattern forming step of forming a plurality of circuit patterns connected to each other through a plated layer of the through hole on both surfaces of the wiring board main body, and on both surfaces of the wiring board main body while filling the through hole. A printed wiring having a through hole, which includes a multilayering step of laminating prepregs and laminating copper foils on both sides of the laminated prepregs, and a removing step of removing an edge portion of a lap portion between the through holes of the through holes. Method of manufacturing a plate.