JPH0532919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a high-density multilayer printed wiring board having blind via holes.

[Prior art] Conventional printed wiring boards have not only holes for inserting components, but also holes for inserting components.
Generally, a via hole is also passed through and a conductive layer is formed on the inner wall of the hole by plating or the like.

Also, multilayer printed wiring boards (hereinafter referred to as multilayer boards)
As devices become more multi-layered, designs are also being adopted in which inner layer via holes are provided in some of the inner layers.

First, as shown in FIG. 2a, holes are made in two double-sided copper-clad laminates 21a and 21b, and a conductor layer 24 is provided by plating the entire surface of both sides, and a predetermined circuit pattern is formed on one of the surfaces. Form. Circuit patterns are formed on both sides of another double-sided copper-clad laminate 21c in the same manner as described above.

Next, the copper-clad laminates 21a, 21b, 21c with the above-mentioned circuit patterns formed thereon and the prepreg layer 31
a and 31b are combined and integrally molded by heating and pressurizing to obtain a multilayer substrate 28.

Next, as shown in FIG. 2b, the multilayer substrate 28
A through hole 29 is provided with a drill.

Next, as shown in FIG. 2c, a conductor layer 30 is provided on the entire surface including the through holes 29 by known electroless plating and electroplating.

Next, as shown in FIG. 2d, a predetermined circuit pattern is formed on the outermost layer of the multilayer substrate 28 by a known tenting method, a resist resin layer 27 is provided, and the multilayer printing having blind via holes 35 is performed. I was getting a wiring board.

In recent years, attempts have been made to increase the packaging density of electronic devices due to performance and economical needs.

For this reason, not only are electronic devices such as ICs and ISIs becoming more highly integrated and faster, but printed wiring boards on which these devices are mounted are also becoming more dense.

For this reason, as an attempt to solve the above-mentioned problem, a method for manufacturing a multilayer printed wiring board includes a blind method for connecting conductor circuits located in the outermost layer and the layer next to the outermost layer.
There is a manufacturing method in which the inner space of the via hole 35 is filled with resin.

[Problem that the invention seeks to solve]

The conventional method for manufacturing the multilayer printed wiring board described above is as follows:
Two insulating plates each having a through hole and a conductive circuit pattern formed only on one side are placed on the outermost layer with the conductive circuit patterns facing each other, and a conductive circuit pattern is previously formed on the inside of the two insulating plates. After stacking one or more insulating plates with prepreg layers in between, when heating and pressurizing them to form a multilayer board, the prepreg layer seeps out from the through holes in the outermost layer, and in the subsequent process, the outermost layer However, when forming a predetermined conductor circuit pattern, etching defects and interlayer thickness defects occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board with a high yield and free from defective etching of conductor circuit patterns and defective interlayer thickness.

[Means for solving problems]

The method for manufacturing a multilayer printed wiring board of the present invention includes the following steps.

(a) A process in which through holes and conductor layers are formed by electroless plating and electroplating on an insulating plate with copper foil laminated on both sides, and conductor circuit patterns are formed on both sides.

(b) On the conductive circuit pattern surface of one side of the insulating plate,
The process of applying thermosetting resin, drying it, and forming a resist resin layer including the inside of the through hole.

(c) At least one insulating plate on which the conductive circuit patterns of the insulating plates having the resist resin layer are arranged in the outermost layer facing each other with the resist resin layer on the outside, and the conductive circuit pattern is previously formed on the inside thereof. A process of stacking the laminate and prepreg layers together and then applying heat and pressure to form a multilayered board.

(d) A step of providing a through hole in a predetermined portion of the multilayer substrate.

(E) A step of forming a conductor layer on the inner wall of the through hole of the multilayer substrate having the through hole.

〔Example〕

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

FIGS. 1A to 1I are cross-sectional views showing steps in order to explain an embodiment of the present invention.

As shown in FIG. 1a, copper foils 2 forming respective conductor layer patterns are provided on both the front and back surfaces of the insulating plate 1.

First, as shown in Fig. 1b, through holes 3 are drilled in the copper-clad laminate on both sides, and
As shown in FIG. c, a conductor layer 4 and a through hole 5 are formed on the entire surface including the through hole 3 by known electroless plating and electroplating, and the conductor layer 4 on both surfaces, that is, the copper foil 2 is connected.

Next, as shown in FIG. 1d, a predetermined circuit pattern portion is coated on both sides with a photosensitive dry film resist 6 using a well-known tenting method, and then a first resist is formed through a developing, etching, and peeling process. Diagram e
Form a circuit pattern on both sides as shown in .

Next, as shown in FIG. 1 f, a thermosetting resin is applied to a predetermined portion of the conductor circuit pattern surface on the outermost layer, and dried to form a resist resin layer 7 including the inside of the through hole. In this way, two laminates are obtained which will become the outermost layers of the multilayered substrate.

Next, as shown in FIG. 1g, circuit patterns are formed on both sides of the double-sided copper-clad laminate using the same method as described above shown in FIGS. The outermost laminated plates 1a and 1b of the multilayered board filled with holes, the laminated plate 1c with only circuit patterns formed on both sides, and the prepreg layer 11a,
11b, and further the above-mentioned laminates 1a, 1
After layer b is placed as the outermost layer, the multilayer substrate 8 is obtained by integrally molding it by heating and pressurizing it. At this time, the through hole 5 shown in FIG.
b is formed by the resist resin 7 without flowing out to the outside.

Next, as shown in FIG. 1h, a through hole 9 is provided by drilling a hole for inserting the component or a hole connecting to the inner layer pattern.

Next, as shown in FIG. 1i, a conductor layer 10 is formed on the inner wall of the through hole 9 in FIG. 1h by known electroless plating to form a multilayer printed wiring having a predetermined blind via hole. Get a board.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

(1) Since the circuit pattern for the outermost layer is formed in advance, defects such as etching residue are eliminated, and yield can be improved.

(2) By filling the through holes with a resist resin layer, there is no prepreg flow that seeps out when insulating plates are laminated, which eliminates interlayer thickness defects and improves yield.

[Brief explanation of the drawing]

1A to 1I are sectional views shown in the order of steps to explain an embodiment of the present invention, and FIGS. 2A to 2D are sectional views shown in the order of steps to explain an example of a conventional method for manufacturing a multilayer printed wiring board. It is. 1... Insulating plate, 1a, 1b, 1c... Laminated board,
2...Copper foil, 3...Through hole, 4...Conductor layer, 5...
...Through hole, 6... Photosensitive dry film resist, 7... Resist resin layer, 8... Multilayer substrate, 9... Through hole, 10... Conductor layer, 11a, 1
1b... prepreg layer, 12... copper foil, 15...
Blind Via Hall, 21a, 21b,
21c...Laminated board, 22...Copper foil, 24...Conductor layer, 25...Through hole, 27...Resist resin layer, 28...Multilayer board, 29...Through hole, 3
0...Conductor layer, 32...Copper foil, 35...Blind via hole.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a multilayer printed wiring board, comprising the following steps. (a) A process in which through holes and conductor layers are formed by electroless plating and electroplating on an insulating plate with copper foil laminated on both sides, and conductor circuit patterns are formed on both sides. (b) On the conductor circuit pattern surface of one side of the insulating plate,
The process of applying thermosetting resin, drying it, and forming a resist resin layer including the inside of the through hole. (c) At least one insulating plate on which the conductive circuit patterns of the insulating plates having the resist resin layer are arranged in the outermost layer facing each other with the resist resin layer on the outside, and the conductive circuit pattern is previously formed on the inside thereof. A process of stacking the substrate and the prepreg layer via heating and pressurizing to form a multilayer substrate. (d) A step of providing a through hole in a predetermined portion of the multilayer substrate. (E) A step of forming a conductor layer on the inner wall of the through hole of the multilayer substrate having the through hole.