JPH03175696A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To improve wiring storing properties so as to enable high density wiring by arranging two sheets of laminates, where thermosetting resin is filled in through holes and conductive circuit patterns are made only on one side each, with the conductive circuit patterns respectively directed inward, and interposing a prepreg between them thereby molding them into a multilayer. CONSTITUTION:Drill processing and panel plating are performed to the optional position of a laminate 2a so as to form a via hole 3a, and the thermosetting resin 4a is filled in the via hole 3a, and baking treatment is done to harden it. Next, belt sander polishing is done to remove the thermosetting resin remaining at the obverse and the reverse of the laminate 2a, whereby a desired conductor circuit pattern 5a is made only at the one side layer. Next, conductor circuit patterns 5a and 5b formed at one side each are directed inward, and a prereg is interposed, and after going through a heating pressurizing process, a multilayer molded substrate 7, where laminates 2a and 2b are integrated through the prepreg layer 6a, is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer wiring board, and in particular, for high-density packaging, the present invention relates to a method for manufacturing a multilayer wiring board, and in particular, for the purpose of high-density packaging, some conductor layers of the via holes on the same grid are divided into one via hole. The present invention relates to a method for manufacturing a multilayer printed wiring board.

[Conventional technology]

BACKGROUND ART Multilayer printed wiring boards (hereinafter referred to as multilayer boards) are becoming more dense in order to increase the S stack of LSIs, ICs, etc., and to improve the performance and economic efficiency of electronic devices.

Two main measures are being taken to address the increasing density of multilayer boards. The first response is to increase the number of conductor layers, that is, to increase the number of layers, and the second response is to increase the number of interconnects between basic lattices. However, in the first approach, the number of via holes that connect the conductor layers between layers increases, which significantly limits the number of wiring lines in the second approach, and hence the wiring capacity. Although this problem has been dealt with by reducing the diameter of the venoa holes, the plate I/hole diameter ratio (aspect ratio) increases, which significantly impedes the productivity of multilayer plates.

As a method to solve this problem, a multilayer printed wiring board having via holes such as surface via holes and blind via holes has been devised.

A typical manufacturing method will be described below using FIGS. 3(A) to 3(C) as examples.

First, a via hole 3a is formed in the laminate 2a by drilling and panel plating, and a conductor circuit pattern 5a is formed on only one side by photo printing (FIG. 3(A)).

Next, the previous laminate 2a is attached to two sets of conductor circuit patterns 5a, 5.
Place b towards the inside/fi17 and prepreg (as shown)
The laminates 2a and 2b are formed through a heating and pressurizing process.
A multilayer molded substrate 7 is obtained in which the components are integrated by the prepreg layer 6 (FIG. 3(B)).

Next, through holes are bored at desired locations on the multilayer molded substrate 7,
A panel plating layer 8 is applied and a through hole 9 is formed.
After S, an outer layer conductor circuit pattern 10 is formed by photo printing method.
A, 10b are formed to form a multilayer printed wiring board 11 by a conventional method.
(Figure 3 (C)).

[Problem to be solved by the invention] The conventional manufacturing method described above has the following drawbacks.

First, filling the via hole with resin depends only on the resin contained in the prepreg. Therefore, the thickness of the laminate can only be about the same thickness as the prepreg layer, and the maximum thickness of this type of laminate is about 0.3 to 0.4 mm, and it is almost impossible to make a laminate with a multilayer structure even more layered. It was impossible.

Therefore, when forming via holes on the same lattice in a multilayer board with more than 10 layers, there are usually only two methods: forming via holes as the inner layer in a double-sided structure, and forming through holes, and the latter through holes can also be formed using laminated boards. The more the number of layers increases, the more the connection becomes mainly one-to-one, and the problem of via hole neck occurs.

The purpose of the present invention is to eliminate the drawbacks of the conventional methods, to make thick laminates or fJI laminates with thick inner layer conductors multilayered by prepreg, and to improve wiring accommodation and enable high-density wiring through multilayer printing. An object of the present invention is to provide a method for manufacturing a wiring board.

[Means to solve the problem]

The method for manufacturing a multilayer printed wiring board of the present invention includes the steps of forming through-holes by performing drilling and panel plating on a laminate having a double-sided or multilayer structure, and filling the through-holes with a thermosetting resin. a step of thermosetting, a step of removing the portions remaining on the front and back sides of the 71-layer board of the thermosetting resin, and a step of removing only one side of the laminate with the through-ball portion filled with the thermosetting resin. A step of forming a conductive circuit pattern, and a step of arranging the two laminates each having a conductive pattern formed on one side with the conductive circuit pattern facing inside, inserting a prepreg, and heating and pressurizing it to form a multilayer. It is characterized by including the following.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIGS. 1A to 1F are vertical cross-sectional views of a multilayer printed wiring board shown in order of steps to explain an embodiment of the present invention.

8-layer molded laminate 2 having an arbitrary inner layer conductor 1a in advance
N/C drilling is performed to form a through hole at an arbitrary location of a, and then panel plating is performed to form a via hole 3a (FIG. 1(A)). Next, a thermosetting resin 4a made by blending 20 to 50% aluminum hydroxide with bisphenol type epoxy resin is filled into the via hole 3a using a roll coater, and baked at 150'C for 90 minutes to heat cure it. (Figure 1 (B)). Next, the remaining thermosetting resin on the front and back sides of the laminate 2a is removed by belt sander polishing, and a desired conductor circuit pattern 5a is formed on only one layer (Fig. 1(C)).Next, the 71-layer board is 2
Sheet 2a.

2b, and a conductor circuit pattern 5a formed on one side,
A prepreg (as shown) is inserted with the laminates 2a and 2b facing inward through a heating and pressing process to obtain a multilayer molded substrate 7 in which the laminates 2a and 2b are integrated by the prepreg layer 6a (the first
Figure (D〉〉.

Next, through holes are bored at desired locations on the multilayer molded substrate 7a, a panel plating layer 8a is applied, and the through holes 9a are formed.
Next, outer layer conductor circuit patterns 10a and 10b are formed by a photoprinting method to obtain a multilayer printed wiring board 11a according to the present invention (FIG. 1(F)).

FIGS. 2(A) to 2(C) are longitudinal cross-sectional views of other embodiments of the present invention. First, the intermediate multilayer board 12 is formed by the same manufacturing method as in the first embodiment (FIG. 2(A)). However, in this case, the conductive circuit pattern 5C is formed on both the front and back sides. Next, the laminated plates 2a and 2b formed in the first embodiment are attached to the intermediate multilayer plate 1.
The multilayer molded substrate 7b in which the laminate plates 2a, 2b and the intermediate multilayer plate 12 are integrated by the prepregs M6a, 6b is obtained by inserting a prepreg (path shown in the figure) on the outside of the laminate plate 2a, 2b and the intermediate multilayer plate 12 by heating and pressure molding. (B)>. Thereafter, through-holes 9b are formed to obtain a multilayer printed wiring board 11b (Fig. 2 (B)).
C)).

In this embodiment, by using the intermediate multilayer board 12, more via holes can be formed on the same lattice point, so higher density packaging is possible.

〔Effect of the invention〕

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

(1> When using a through-hole as a via hole, it can be arranged as a divided via hole on the same lattice point, improving wiring accommodation and enabling high-density wiring.

(2) It is now possible to collectively mold any number of thick multi-layer boards, and especially when a large number of surface mount components are mounted on both sides, the wiring on the same layer is divided into via-hole wiring. It is possible to relatively improve the wiring accommodation capacity by providing wiring between the front and back sides using through-hole type via holes.

[Brief explanation of drawings]

FIGS. 1(A) to (F) are longitudinal cross-sectional views of a multilayer printed wiring board shown in the order of steps to explain one embodiment of the present invention, and FIGS. A vertical cross-sectional view of the main steps of a multilayer printed wiring board shown in order of steps to explain an example of
FIGS. 3(A) to 3(C) are longitudinal cross-sectional views shown in order of steps to explain an example of a conventional method for manufacturing a multilayer printed wiring board. la, lb, 1cm inner layer conductor, 2a, 2b...
Laminated board, 3a, 3b, 3c = Via hole, 4a. 4b, 4cm--thermosetting resin, 5a, 5b, 5c=
- Conductor circuit pattern, 6.6a, 6b...Prepreg layer, 7 7a, 7b...Multilayer molded board, 8.8a. 8b... Panel plating layer, 9.9a, 9b... Penetration through hole, 10a, 10b... Outer layer conductor circuit pattern, 11. lla, 11b--Multilayer printed wiring board, 12... Intermediate multilayer board.

Claims (1)

[Claims] A process of forming through-holes by performing drilling and panel plating on a laminate having a double-sided or multilayer structure, a process of filling the through-holes with a thermosetting resin and then thermosetting it, and a process of thermosetting the thermosetting resin. a step of removing remaining portions on the front and back sides of the thermosetting resin laminate, a step of forming a conductive circuit pattern on only one side of the laminate with the through-hole portion filled with thermosetting resin, and a conductive pattern on the one side. The manufacturing of a multilayer printed wiring board comprising the steps of arranging two laminates each having a conductor circuit pattern facing inward, interposing a prepreg, and heating and pressurizing the two laminates to form a multilayered structure. Method.