JP2003258428A - Multilayered printed board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make another wiring which is not connected electrically to internal circuits passable through a via hole in which the internal circuits are connected to each other in a build-up multilayered printed board. <P>SOLUTION: The multilayered printed board includes at least two layers of a printed board 10 used as a core material having first circuit wiring 11 which becomes one internal circuit on its surface and an insulating resin layer 20 formed on the wiring 11. At the time of electrically connecting second circuit wiring 31 formed on the resin layer 20 to the first circuit wiring 11 of the board 10 through a via hole 21 formed by a laser beam, the via hole 21 is formed in a cone-shaped hole and the connecting terminal section 31a of the second circuit wiring 31 is connected to the first circuit wiring 11 through part of the internal surface of the cone-shaped via hole 21 so that the other wiring 32 which is not connected electrically to the second circuit wiring 31 is passed through the remaining part of the cone-shaped hole 21. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed circuit board and a method for manufacturing the same, and more particularly to a wiring forming technique for forming a multilayer circuit wiring through an insulating resin layer having a laser via hole. It is a thing.

[0002]

2. Description of the Related Art A build-up type is one of the methods for manufacturing a multilayer printed circuit board. In the build-up type, a printed board made of, for example, a copper clad laminated board is used as a core material, an insulating resin layer is sequentially laminated on the board, and a circuit wiring is formed for each insulating resin layer.

An example of this will be described with reference to FIG.
Circuit wiring 1 with a predetermined pattern on both sides of the printed circuit board 1
a and 1b are formed. If one of the circuit wirings 1a is an inner layer circuit wiring, the inner layer circuit wiring forming surface side is roughened by blackening treatment or the like, and then the insulating resin layer (buildup resin layer) 2 is formed on the circuit. It is formed thicker than the thickness of the wiring 1a.

Next, a via hole 2a having a depth reaching the circuit wiring 1a is formed in the insulating resin layer 2. This perforation is selected according to the material of the insulating resin. For example, in the case of an epoxy resin, a laser drilling method is adopted, and in the case of a photo-via developing type insulating resin, the insulating resin is exposed by applying a predetermined mask, and then developed and removed. Done.

After drilling, a plating layer 3 is formed on the insulating resin layer 2 including the inside of the via hole 2a, and the plating layer 3 is etched to form a circuit wiring on the insulating resin layer 2 that is electrically connected to the circuit wiring 1a. 3a is formed. In this way, the required number of layers of circuit wiring is formed.

FIG. 4 schematically shows an enlarged perspective view of the via hole 2a. In the via hole 2a and its periphery, the circuit wiring 3 is formed.
Since the copper plating a exists, when forming another wiring 4 which is not electrically connected to the circuit wiring 3a on the insulating resin layer 2, it is necessary to avoid the via hole 2a.

Usually, the diameter of the via hole 2a is 0.1 to 0.2.
Although it is about mm, the presence of the via hole 2a is a great obstacle to the wiring design when a large number of wirings having a line width of about 30 to 100 μm are formed at high density.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a build-up type multilayer printed circuit board,
Another purpose is to allow another wiring, which is not electrically connected to the circuit wiring, to pass through the via hole that connects the circuit wirings.

[0009]

In order to solve the above problems, a first invention of the present application is a printed circuit board as a core material having a first circuit wiring as an inner layer circuit on its surface, and the first printed circuit board described above. At least two insulating resin layers formed on the circuit wiring are included, and the insulating resin layer has a laser via hole having a depth reaching the first circuit wiring, and the laser via is provided on the insulating resin layer. In a multilayer printed circuit board in which a second circuit wiring that is electrically connected to the first circuit wiring through a hole is formed, the laser via hole is a mortar-shaped hole, and the connection terminal portion of the second circuit wiring is the mortar-shaped. It is characterized in that it is connected to the first circuit wiring through a part of the inner surface of the hole.

As described above, since the laser via hole is a mortar-shaped hole and the connection terminal portion of the second circuit wiring is formed only on a part of the inner surface of the mortar-shaped hole, the second circuit wiring is formed in the remaining portion of the mortar-shaped hole. Can form another non-conducting wiring. The first invention also includes a multilayer printed board in which another wiring is formed in the mortar-shaped hole.

A second invention of the present application is a printed circuit board as a core material having a first circuit wiring as an inner layer circuit on a surface thereof, and an insulating resin layer formed on the first circuit wiring of the printed circuit board. Of at least two layers, the insulating resin layer has a laser via hole having a depth reaching the first circuit wiring, and is electrically connected to the first circuit wiring through the laser via hole on the insulating resin layer. In the multilayer printed circuit board on which the second circuit wiring is formed, the connection terminal portion of the second circuit wiring is connected to the first circuit wiring through a part of the inner surface of the laser via hole, and the laser via hole is formed. Is characterized in that it is filled with an electrically insulating permanent filling material so as to be substantially flush with the insulating resin layer.

According to the second invention, since the via hole is closed by the permanent filling material, the second hole is also formed on the via hole.
It is possible to form another wiring that is non-conductive from the circuit wiring,
The present invention also includes a multilayer printed circuit board in which another wiring is actually formed on the permanent filling material. Also in this second invention, it is preferable that the laser via hole is a mortar-shaped hole.

A third invention of the present application relates to the manufacturing method of the first invention, wherein insulation is provided on the first circuit wiring forming surface of a printed circuit board as a core material having a first circuit wiring serving as an inner layer circuit on the surface. Step of forming a conductive resin layer, a second step of forming a laser via hole having a depth reaching the first circuit wiring in the insulating resin layer in a mortar shape by laser light, and an inner surface of the laser via hole Including the step of forming a plating layer on the insulating resin layer, and a second circuit wiring connecting to the first circuit wiring on the plating layer through a part of the inner surface of the laser via hole; A fourth step of providing an etching resist for forming another wiring that is non-conducting from the second circuit wiring that passes through the remaining portion of the inner surface of the laser via hole, and etching the exposed unnecessary plating portion of the plating layer It is characterized in that at least implement the fifth step to further removal.

A fourth invention of the present application relates to the manufacturing method of the second invention, wherein the first printed circuit board as a core material has a first circuit wiring as an inner layer circuit on a surface thereof.
A first step of forming an insulating resin layer on a circuit wiring formation surface, a second step of forming a laser via hole in the insulating resin layer by laser light to a depth reaching the first circuit wiring, and the laser A third step of forming a first plating layer on the insulating resin layer including the inner surface of the via hole, and connecting the first plating layer to the first circuit wiring through a part of the inner surface of the laser via hole. And a fourth step of forming an etching resist on the first plating layer, and an unnecessary plating portion exposed on the remaining portion of the inner surface of the laser via hole is removed by etching to remove the inner surface of the laser via hole. A fifth step of forming a connection terminal portion connected to the first circuit wiring in a part thereof, and an electrically insulating permanent filling material in the laser via hole so as to be substantially flush with the insulating resin layer. Filling A sixth step, a sixth step of forming a second plating layer over the first plating layer and the permanent filling material, and an etching resist having a predetermined pattern formed on the second plating layer, and then etching At least a seventh step of forming a second circuit wiring connected to the first circuit wiring via at least the connection terminal portion is performed.

Also in this fourth invention, it is preferable that the laser via hole is formed in a mortar shape in the second step. Further, the fourth invention includes further forming another wiring, which is not electrically connected to the second circuit wiring, on the permanent filling material in the seventh step.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, two embodiments of the present invention will be described with reference to FIGS. 1 (a)-
2D is an explanatory view of the manufacturing process of the first embodiment, and FIG.
(A)-(d) is explanatory drawing of the manufacturing process of 2nd Embodiment.

First, in the first embodiment, FIG.
As shown in (a), after the circuit wirings 11 and 12 are formed on both surfaces of a printed circuit board 10 as a core material made of a copper clad laminated board, an insulating resin layer 20 as a build-up resin layer is formed on one surface thereof. Stack.

In this case, the circuit wiring (first circuit wiring) 11
Is an inner layer circuit, the insulating resin layer 20 is laminated on the side where the first circuit wiring 11 is formed. The method for forming the insulating resin layer 20 may be a curtain coating method, a roll coating method, a printing method, or the like. Prior to the lamination, it is preferable that the surface of the printed circuit board 10 is roughened by, for example, blackening treatment. In some cases, the insulating resin layer 2
You may use a prepreg for 0.

In the first embodiment, the insulating resin layer 20 is made of epoxy resin. A via hole 21 having a depth reaching the first circuit wiring 11 is formed in the insulating resin layer 20.
However, in the present invention, perforation is performed by laser irradiation.

Therefore, the via hole 21 is a laser via hole and has a mortar shape. The mortar shape includes all the shapes in which the opening diameter on the upper surface side is larger than the opening diameter on the bottom surface and the inner surface is a smooth inclined surface.

The inclined surface may be straight or curved when viewed in cross section. The reason that the via hole 21 is a laser via hole is that it is easy to form a mortar shape by using a laser. Actually speaking, the upper surface side opening diameter is 0.10 to 0.20 mm,
The bottom side opening diameter is preferably about 0.07 to 0.17 mm.

Next, as shown in FIG. 1B, the via hole 2
The plating layer 30 is formed on the insulating resin layer 20 including inside 1. The plating method is not particularly limited and may be, for example, a combination of electroless plating and electroplating or only electroless plating.

After forming the plating layer 30, FIG. 1 (c1)
As shown in the sectional view and the enlarged perspective view of FIG. 2 (c2), an etching resist 40 for forming the circuit wiring of the insulating resin layer 20 is formed on the plating layer 30.

In this example, the etching resist 4
Although two etching resists 41 and 42 are included as 0, referring to the sectional view of FIG. 1D1 and the enlarged perspective view of FIG. 10 is for forming a specific circuit wiring (second circuit wiring) 31 connected to the first circuit wiring 11, and the other etching resist 42 is another circuit wiring which is not electrically connected to the second circuit wiring 31. For forming 32.

In this example, the first circuit wiring 11 of the printed board 10 is divided by etching, one of the divided first circuit wirings 11 is connected to the second circuit wiring 31, and the divided first circuit wiring 31 is connected. In order to connect the other side of the wiring 11 to another circuit wiring 32 that is not electrically connected to the second circuit wiring 31,
As shown in FIG. 1 (c1) and FIG. 1 (c2), the etching resist 41 and the etching resist 42 are opposed to each other at a predetermined interval at the bottom of the via hole 21.

As described above, after forming the etching resist 40 including the etching resists 41 and 42 on the plating layer 30, the first circuit wiring 11 of the printed circuit board 10 is divided by etching and one of the divided portions is formed. The second circuit wiring 31 connected to and the divided circuit wiring 32 connected to the other are formed.

What is important here is that in the present invention, the connection terminal portion 31a of the second circuit wiring 31 is formed not on the entire inner surface of the mortar-shaped via hole 21, but on a part thereof.

As a result, FIG. 1 (d1) and FIG.
As shown in 2), another circuit wiring 32, which is not electrically connected to the second circuit wiring 31, is provided on the remaining portion of the inner surface of the via hole 21 as necessary.
Therefore, the wiring density can be further increased.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the via hole 21 of the first embodiment is filled, and another wiring can be formed on the via hole 21, and FIGS. 1A to 1B of the first embodiment are shown. ) Until the same process is followed.

As described with reference to FIG. 1B, the plating layer 30 in the first embodiment is used as the first plating layer, and the insulating resin layer 2 including the inside of the via hole 21 of the insulating resin layer 20 is included.
After the first plating layer 30 is formed on the surface of the substrate 0, in the second embodiment, the cross-sectional view of FIG.
As shown in the enlarged perspective view of 2), the etching resist 40 is formed on the first plating layer 30 so as to connect the first plating layer 30 to the first circuit wiring 11 on the printed circuit board 10 side through a part of the inner surface of the via hole 21. To form.

That is, the first plating layer 30 on the insulating resin layer 20 is covered with the etching resist 40, and at the inner surface of the via hole 21, a part of the first plating layer 30 reaches the first circuit wiring 11. Like a tongue, and the first portion of the remaining portion of the inner surface of the via hole 21 and its peripheral edge is formed.
The plating layer 30 is exposed.

Then, after removing the unnecessary first plating layer 30 exposed on the inner surface of the via hole 21 by etching, the etching resist 40 is peeled off, and FIG.
As shown in the sectional view and the enlarged perspective view of FIG. 2B2, the connection terminal portion 31a of the first plating layer 30 connected to the first circuit wiring 11 is formed on a part of the inner surface of the via hole 21.

Next, as shown in the sectional view of FIG.
The via hole 21 is filled with a permanent filling material 22, and the surface of the permanent filling material 22 is polished so as to be substantially flush with the first plating layer 30. For the permanent filling material 22, for example, an epoxy thermosetting resin can be used. The permanent filling material is a filling material that is not removed from the insulating resin layer thereafter.

Next, the second plating layer 50 is formed on the first plating layer 30 and the permanent filling material 22 by, for example, electroplating.
After forming, the etching resist 60 for forming the wiring required for the insulating resin layer 20 is formed. Although the etching resist 60 may be formed by a printing method, a photosensitive dry film is used in this example.

In the second embodiment, as shown in FIG. 2C, the first circuit wiring of the printed circuit board 10 is formed as the etching resist 60 via the connection terminal portion 31a left in the via hole 21. Etching resist 61 for obtaining the second circuit wiring to be connected to 11 and another etching wiring for non-conducting the second circuit wiring and passing through the permanent filling material 22. 62
And form.

Such etching resists 61, 62
After forming, the exposed unnecessary second plating layer 50 and the underlying first plating layer 30 are both removed by etching.

As a result, as shown in the sectional view of FIG. 2 (d1) and the enlarged perspective view of FIG. 2 (d2), the printed circuit board 10 is connected through the connection terminal portion 31a left in the via hole 21. A second circuit wiring 51 connected to the first circuit wiring 11 and another circuit wiring 52 which is non-conductive with the second circuit wiring 51 and passes over the permanent filling material 22 are formed.

The second circuit wiring 51 is formed by the first plating layer 3
0 and the second plating layer 50, but the portion of another circuit wiring 52 passing over the permanent filling material 22 is the second plating layer 5
It consists of only one layer of 0.

In each of the above embodiments, the insulating resin layer 20 is one layer, but if necessary, an insulating resin layer may be further laminated, laser via holes may be appropriately formed, and the inner layer circuit wirings may be connected. can do.

[0040]

As described above, according to the present invention,
In the build-up type multilayer printed circuit board, it is possible to pass another wiring, which is not electrically connected to the inner layer circuit, over the via hole that connects the inner layer circuits, so that the wiring density can be further increased.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a manufacturing process in a first embodiment of the present invention.

FIG. 2 is an explanatory view for explaining a manufacturing process in the second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a via hole portion of a conventional build-up type multilayer printed circuit board.

FIG. 4 is an enlarged perspective view showing a via hole portion of FIG.

[Explanation of symbols]

10 Printed circuit board (core material) 11 First circuit wiring (inner layer circuit) 20 Insulating resin layer 21 via hole 30 plating layer (first plating layer) 31,51 Second circuit wiring 31a Connection terminal part 32, 52 different wiring 40,60 Etching resist 50 Second plating layer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5E314 AA25 AA32 BB15 FF01 GG26                 5E339 AC01 AD05 BC01 BC02 BD02                       BD08 BE13 CE03 CE12 CG04                       GG10                 5E346 AA15 AA35 CC08 CC31 CC32                       CC55 CC57 CC58 DD23 DD25                       DD32 DD33 DD48 FF13 FF15                       FF22 FF28 FF42 FF50 GG15                       GG17 GG22 GG23 HH25

Claims (9)

[Claims] 1. A printed circuit board as a core material having a first circuit wiring as an inner layer circuit on a surface thereof, and at least two layers of an insulating resin layer formed on the first circuit wiring of the printed circuit board, The insulating resin layer has a laser via hole having a depth reaching the first circuit wiring, and a second circuit wiring is formed on the insulating resin layer so as to be electrically connected to the first circuit wiring through the laser via hole. In the multilayer printed circuit board, the laser via hole is composed of a mortar-shaped hole, and the connection terminal portion of the second circuit wiring is connected to the first circuit wiring through a part of the inner surface of the mortar-shaped hole. Characteristic multilayer printed circuit board. 2. The multilayer printed circuit board according to claim 1, wherein another wiring that is not electrically connected to the second circuit wiring is further formed on the remaining portion of the inner surface of the mortar-shaped hole. 3. A printed circuit board as a core material having a first circuit wiring as an inner layer circuit on the surface, and at least two layers of an insulating resin layer formed on the first circuit wiring of the printed circuit board, The insulating resin layer has a laser via hole having a depth reaching the first circuit wiring, and a second circuit wiring is formed on the insulating resin layer so as to be electrically connected to the first circuit wiring through the laser via hole. In the multi-layered printed circuit board, the connection terminal portion of the second circuit wiring is connected to the first circuit wiring through a part of the inner surface of the laser via hole, and the laser via hole has a permanent electrical insulation property. A multi-layer printed circuit board, wherein the filling material is filled so as to be substantially flush with the insulating resin layer. 4. The multilayer printed circuit board according to claim 3, wherein another wiring that is not electrically connected to the second circuit wiring is further formed on the permanent filling material. 5. The multilayer printed board according to claim 3, wherein the laser via hole is a mortar-shaped hole. 6. A first step of forming an insulative resin layer on the first circuit wiring formation surface of a printed circuit board as a core material having a first circuit wiring to be an inner layer circuit on the surface; Forming a laser via hole having a depth reaching the first circuit wiring in a mortar shape in the conductive resin layer;
A third step of forming a plating layer on the insulating resin layer including the inner surface of the laser via hole, and the first circuit wiring through a part of the inner surface of the laser via hole on the plating layer. Second circuit wiring to connect,
A fourth step of providing an etching resist for forming another wiring that is non-conductive from the second circuit wiring that passes through the remaining portion of the inner surface of the laser via hole, and an unnecessary plating portion where the plating layer is exposed. And a fifth step of removing by etching, and performing the above steps in this order, a method of manufacturing a multilayer printed circuit board. 7. A first step of forming an insulating resin layer on the first circuit wiring formation surface of a printed circuit board as a core material having a first circuit wiring to be an inner layer circuit on the surface, and the insulating by laser light. A second step of forming a laser via hole having a depth reaching the first circuit wiring in the conductive resin layer, and a third step of forming a first plating layer on the insulating resin layer including the inner surface of the laser via hole And a step of connecting the first plating layer to the first circuit wiring through a part of an inner surface of the laser via hole.
A fourth step of forming an etching resist on the plating layer, and an unnecessary plating portion exposed at the rest of the inner surface of the laser via hole are removed by etching, and the first portion is formed on a part of the inner surface of the laser via hole. A fifth step of forming a connection terminal portion connected to the circuit wiring, and a sixth step of filling the laser via hole with an electrically insulating permanent filling material so as to be substantially flush with the insulating resin layer. A sixth step of forming a second plating layer over the first plating layer and the permanent filling material, and forming an etching resist on the second plating layer with a predetermined pattern, and then etching to form at least the connection. A second connecting to the first circuit wiring via a terminal portion
7. A method for manufacturing a multilayer printed circuit board, comprising performing at least a seventh step of forming circuit wiring. 8. The method for manufacturing a multilayer printed board according to claim 7, wherein in the second step, the laser via hole is formed in a mortar shape. 9. The method for manufacturing a multilayer printed circuit board according to claim 7, wherein in the seventh step, another wiring that is non-conductive with the second circuit wiring is further formed on the permanent filling material.