JPH05243733A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To enable the formation of a high-density wiring circuit by connecting printed wiring boards for inner layers by means of a semithrough hole and a through hole. CONSTITUTION:A laminated board 1 clad with copper is made, and a through hole 2a is formed. Next, a copper-plated layer 3 and a through hole 2 are made. Next, a wiring circuit 4 is made. Next, a photosensitive insulating resin layer 5 is applied all over the surface layer of the laminated substrate 1 clad with copper by roller coating method, and the photosensitive insulating resin layer 5 is exposed and developed. Next, a plated resist layer 6 is made on the surface layer of the copper-lined laminated layer board 1, and a specified wiring circuit part is exposed and developed. Next, a wiring circuit 4 is made by electroless plating method, and the needless plated resist layer 6 is removed. Next, a resin layer 5 is made, and a semithrough hole 7a is made in the specified position. Next, a plated resist layer 6 is made, and the plated resist layer 6 is exposed and developed. Next, a semithrough hole 7 and an outermost-layer circuit 8 are made, and the needless plated layer 6 is removed.

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 multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board in which a surface copper foil portion and an inner layer printed wiring circuit are connected by semi-through holes.

[0002]

2. Description of the Related Art Generally, a method shown in FIGS. 5A to 6C is often used for manufacturing an inner layer printed wiring board having through holes. In this method, first, as shown in FIG. 5A, an inner layer printed wiring board 11 having through holes obtained by a known method is used as an adhesive resin plate obtained by impregnating glass cloth with a thermosetting adhesive resin (hereinafter, referred to as In order to improve the adhesion strength with the prepreg 13), the surface of the wiring circuit is roughened by oxidation, and the prepreg 13 is combined and heat-pressed.

Next, as shown in FIG. 5 (b), the adhesive resin 14 eluted from the through hole to the surface copper foil portion 12 is applied to the abrasive 1
The surface is polished and polished by 5.

Next, as shown in FIG. 6A, all-layer through-holes 1
Drill 6a.

Next, as shown in FIG. 6 (b), all-layer through-holes 1
A copper plating layer 17 is formed in 6a and on the surface of the surface copper foil portion 12 to form a through-hole for all layers.

Next, as shown in FIG. 6 (c), there is a manufacturing method in which a wiring circuit is formed on the surface by a known method.

[0007]

However, in recent years, the number of wiring circuits using fine through holes has increased rapidly.
In the conventional manufacturing method, the connections between the printed wiring boards for inner layers were made by multi-layer molding using the printed wiring boards for inner layers having through holes, so by making the drilling holes for thin inner layer boards smaller, In addition to problems such as a decrease in accuracy, an increase in drill cost, a decrease in handleability in the plating process, and a decrease in the wiring area of the surface wiring circuit due to the fine through holes, there are the following problems.

1. Since the printed wiring board for the inner layer is connected only through the through holes of all layers, a high-density wiring circuit cannot be formed.

2. In order to make a high-density multilayer printed wiring board, a plurality of inner layer printed wiring boards having through holes are required, and thus a large number of man-hours are required to manufacture the inner layer printed wiring board.

3. The inner layer printed wiring board having a through hole has a thin plate thickness, so that a handling error is likely to occur during a process such as drilling, plating, circuit formation, etc., resulting in a poor manufacturing yield.

4. After molding under heat and pressure, the molding resin elutes from the through holes that connect the surface copper foil and the inner layer wiring circuit of the next layer, so surface polishing on the surface copper foil is necessary, and the effects of polishing scratches etc. when forming the outer layer circuit Manufacturing yield is poor.

An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board, which enables formation of high-density wiring circuits, has a high manufacturing yield, and saves man-hours.

[0013]

A method for manufacturing a multilayer printed wiring board according to the present invention comprises a thermo-compression bonding and a coating of a photosensitive insulating resin layer on the surface of a copper clad laminate having a surface wiring circuit and through holes. A step of forming by one of the methods,
Exposing a predetermined photosensitive insulating resin layer to develop and removing the unnecessary photosensitive insulating resin layer; forming a plating resist layer on the surface layer surface of the copper clad laminate; A conductor layer is formed by exposing the resist layer to light and developing the unnecessary plating resist layer to remove it, and at the plating resist layer removing portion by any one of electroless copper plating and conductive paste application. To form a wiring circuit and remove the plating resist layer, and to form a second layer of photosensitive insulating resin for embedding the wiring circuit on the exposed photosensitive insulating resin layer; A step of boring a semi-through hole connecting the wiring circuit and the surface wiring circuit from the surface of the photosensitive insulating resin layer of the eye, and forming a plating resist layer on the outermost layer and exposing the unnecessary semi-through hole Present plating resist layer Including and removing it, and removing the plating resist layer and the conductor layer is formed on the plating resist layer removal portion remaining to form a semi-through holes and the outermost layer circuit.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 (a) to 3 (d) are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, a copper clad laminated substrate, which is a material, is formed.

Next, as shown in FIG. 1B, the through hole 2a is formed by a known method.

Next, as shown in FIG. 1C, a copper plating layer 3 and a through hole 2 are formed by a known method.

Next, as shown in FIG. 1D, the wiring circuit 4 is formed by a known method.

Next, as shown in FIG. 1E, the photosensitive insulating resin layer 5 is applied to the entire surface of the copper clad laminate 1 by the roller coating method.

Next, as shown in FIG. 1F, the photosensitive insulating resin layer 5 is exposed and developed by a known method.

Next, as shown in FIG. 1G, a predetermined plating resist layer 6 is formed on the surface layer surface of the copper clad laminate 1.

Next, as shown in FIG. 2A, a predetermined wiring circuit portion is exposed and developed.

Next, as shown in FIG. 2B, a predetermined wiring circuit 4 is formed by electroless plating.

Next, as shown in FIG. 2C, the unnecessary plating resist layer 6 is removed.

Next, as shown in FIG. 2D, the same resin layer 5 as in the step of FIG. 1E is formed.

Next, as shown in FIG. 2 (e), a semi-through hole 7a is formed at a predetermined position.

Next, as shown in FIG. 3A, the plating resist layer 6 is formed.

Next, as shown in FIG. 3B, the plating resist layer 6 is exposed and developed.

Next, as shown in FIG. 3C, the semi-through through hole 7 and the outermost layer circuit 8 are formed by electroless plating.

Next, as shown in FIG. 3D, the unnecessary plating resist layer 6 is removed to obtain a multilayer printed wiring board having the outermost layer circuit 8 including the semi-through hole 7.

In addition to the double-sided copper-clad laminated board, a multilayer copper-clad laminated board can be used as the material. Further, as the photosensitive insulating resin material, epoxy resin, phenol resin, polyimide resin or the like can be used. Further, the film thickness of the photosensitive insulating resin layer 5 is suitably 0.1 to 0.4 mm, and as a coating method, a spray coating method, a dipping method, a curtain coater method can be used in addition to the roller coating method. Further, in the electroless copper plating layer 3, a plating thickness of 18 to 70 μm is suitable, and a copper paste may be printed instead of the electroless copper plating.

The diameter of the semi-through hole 7 is preferably 0.1 to 0.5 mm, and the outermost layer circuit 8 is suitable.
It is necessary to punch holes from the wiring circuit 4 to the wiring circuit 4 of the multilayer printed wiring board to connect the wiring circuits of all layers.

FIG. 4 is a cross-sectional view of components mounted on a multilayer printed wiring board according to an embodiment of the present invention.

The multilayer printed wiring board manufactured in this way is shown in FIG.
As described above, by utilizing the through hole 2 of the multi-layered copper clad laminate of the surface mount component 9 which is now widely used, the soldering component 10 can also be used as a component.

[0036]

As is apparent from the above, according to the present invention, the following effects can be obtained, and a highly reliable high-density multilayer printed wiring board can be manufactured.

1. Since the connection between the printed wiring boards for inner layers is performed by the semi-through holes and the through holes, a high-density wiring circuit can be formed.

2. Since the inner layer printed wiring board having the through holes is not required, the number of manufacturing steps of the multilayer printed wiring board can be reduced.

3. Since the printed wiring board for the inner layer having the through holes is not required, the inner layer perforation plating step is unnecessary, the handling and mounting defects in the step are reduced, and the high manufacturing yield can be obtained.

4. Since the printed wiring board for the inner layer having the through holes is not required, the surface polishing on the outer layer copper foil is not necessary, the polishing scratches are reduced, and high product quality can be obtained.

[Brief description of drawings]

1A to 1D are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

2A to 2D are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

3A to 3C are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

FIG. 4 is a cross-sectional view of components mounted on a multilayer printed wiring board according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the order of steps for explaining an example of a conventional method for manufacturing a multilayer printed wiring board.

FIG. 6 is a cross-sectional view showing the order of steps for explaining an example of a conventional method for manufacturing a multilayer printed wiring board.

[Explanation of symbols]

 1 Copper Clad Laminated Board 2 Through Hole 2a Through Hole 3,17 Copper Plating Layer 4 Wiring Circuit 5 Photosensitive Insulating Resin Layer 6 Plating Resist Layer 7 Half Through Through Hole 7a Half Through Hole 8 Outermost Layer Circuit 9 Surface Mount Component 10 Soldering Components 11 Printed wiring board for inner layer 12 Surface copper foil portion 13 Prepreg 14 Eluted adhesive resin 15 Abrasive agent 16 All-layer through-hole 16a All-layer through-hole

Claims (1)

[Claims] 1. A step of forming a photosensitive insulating resin layer on the surface of a copper clad laminate having a surface wiring circuit and through holes by either one of thermocompression bonding and coating.
Exposing a predetermined photosensitive insulating resin layer to develop and removing the unnecessary photosensitive insulating resin layer; forming a plating resist layer on the surface layer surface of the copper clad laminate; A conductor layer is formed by exposing the resist layer to light and developing the unnecessary plating resist layer to remove it, and at the plating resist layer removing portion by any one of electroless copper plating and conductive paste application. To form a wiring circuit and remove the plating resist layer, and to form a second layer of photosensitive insulating resin for embedding the wiring circuit on the exposed photosensitive insulating resin layer; A step of boring a semi-through hole connecting the wiring circuit and the surface wiring circuit from the surface of the photosensitive insulating resin layer of the eye, and forming a plating resist layer on the outermost layer and exposing the unnecessary semi-through hole Present plating resist layer And a step of removing the remaining plating resist layer by forming a conductor layer in the plating resist layer removing portion to form a semi-through hole and an outermost layer circuit. Manufacturing method of printed wiring board.