JPH02153594A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To form a non-penetrating-hole of proper depth without being influ enced by the thickness of a board and to plate the inside of the blind via hole and an outer base at the same time by a method wherein a hole boring process by a drill is not performed in a blind via hole forming process. CONSTITUTION:A glass epoxy double-sided copper clad laminar board is patterned, and a metal layer is laminated thereon through the intermediary of glass epoxy prepreg, which is hot-pressed and patterned to form a four- layered film which serves as an inner board 1. Adhesive layers 2 are transferred onto both the sides of the inner board 1 through a roll coater, and then a metal layer 3 is hot pressure-bonded to both the sides of the board 1 to obtain a multilayer board 4. Then, a part of the metal layer 3 at a specified position is removed in a circle of a specified diameter through etching to expose the adhesive layer 2, and furthermore an inner pattern 6 inside the adhesive layer 2 exposed by etching is exposed. Thereafter, a through-hole 8 is board by a drill to serve as a through-hole, plating is performed to connect the exposed pattern 6 and the metal layer 3, and a blind via hole 7 and an outer pattern 10 of the board 4 are formed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a multilayer printed wiring board used for mounting electronic components of various electronic devices, and particularly relates to a multilayer printed wiring board that is used to mount electronic components of various electronic devices. The present invention relates to a multilayer printed wiring board having a multilayer printed wiring board.

(Prior art) In conventional printed wiring boards, it is common to pass through holes or via holes for inserting components and form a conductor layer on the inner wall of the hole by plating, etc. However, in recent years, Due to the performance and economical needs of electronic devices, the density of packaging is increasing, and the demand for higher density printed wiring boards is also increasing.

However, in conventional multilayer printed wiring boards in which via holes are provided as through holes,
This not only causes the problem of significantly hindering the wiring density for higher density, but also leads to higher multilayering.
The aspect ratio (the ratio of the thickness of the outer layer base material to the diameter of the hole drilled in the outer layer base material) increases, and the reliability and economic efficiency of the through hole are not necessarily satisfactory.

On the other hand, 9. A design for improving wiring density using blind via holes has been proposed, and from the viewpoint of manufacturing the blind via holes, the following two attempts have been made.

That is, the first attempt was to conduct a blind drill using a drill.
This is a method of forming via holes, and after forming a multilayer board of the desired number, a necessary blind via hole is formed using a drill. In this case, it is necessary to control the depth of the drill in the thickness direction of the multilayer board, but when manufacturing multilayer boards, variations in board thickness between lots are unavoidable, and the bottom of the blind via hole and the next The disadvantage is that the distance between the layer and the conductor circuit varies, resulting in large variations in electrical characteristics. In addition, there was a restriction that holes had to be drilled on one side at a time and through-holes had to be drilled, making it unsuitable for mass production.

The second attempt is to perform aFR on a printed wiring board with via holes provided in advance via prepreg. Since this method uses a printed wiring board with via holes in the outermost layer, the thickness of the copper plating on the outermost layer becomes thick, making it unsuitable for fine patterns.It also does not meet economic needs. It wasn't something.

(Problems to be Solved by the Invention) As described above, the problems to be solved by the present invention are the reduction in wiring density and manufacturing cost of conventional multilayer printed wiring boards. It is lI.

SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method that allows easy mass production of multilayer printed wiring boards having blind via holes.

(Means for Solving the Problems) The means taken by the present invention to solve the problems described below are as follows: A metal layer is formed via an adhesive layer on an inner layer substrate that has been patterned or laminated and patterned in advance. The metal layer at the desired position is removed, the adhesive layer is exposed, and the first step is performed.
After removing the exposed adhesive layer and exposing the desired inner layer pattern, at least chemical steel plating is applied to electrically connect the exposed inner layer pattern and the metal layer to form an outer layer pattern. By forming a multilayer printed wiring board with blind via holes.

Next, an example of the method for manufacturing a multilayer printed wiring board according to the present invention will be described in more detail with reference to the drawings.

First, (a) an inner layer substrate (1) is formed by a conventionally commonly used method. At this time, an inner layer pattern (6) is formed on the inner layer substrate (1).

Next, (b) a desired multilayer substrate (4) is formed by hot-pressing a metal layer (3) such as copper foil on this inner layer substrate (1) via an adhesive layer (2), and (c ) This multilayer board (4
) is removed at the position where the blind via hole (7) is to be formed.In other words, in this step (C), the adhesive layer (2) to be removed in the first step is exposed. The partially enlarged sectional view of FIG. 1 shows the multilayer substrate (4) with the metal layer (3) removed at a predetermined position.

Figure 2 shows the adhesive layer (2) exposed in step (c) above.
was removed to expose the inner layer pattern (6) ('d)
It is a partially enlarged sectional view showing a process. In this step (d), the inner layer pattern (6) electrically connected to the metal layer (3) is exposed by providing a hole (5) that becomes a blind via hole (7).

Thereafter, a through hole (8) to be a through hole is bored in the multilayer substrate (4) by a known method, and then copper plating (9) is performed in this through hole (8). This copper plating (9) is performed at least by chemical copper plating,
At the same time, this chemical copper plating is applied to the inside of the through hole (8), and at the same time, (e) the surface of the metal layer (3), the inside of the hole (5) which will become the blind via hole formed in step Copper plating is performed on the inner layer pattern (6) exposed within this hole (5). By this copper plating, an outer layer pattern (10) is formed which electrically connects the metal layer (3) and the inner layer pattern (6) f), thereby completing the desired multilayer printed wiring board. It is the partially enlarged sectional view of FIG. 3 showing the completed state of this multilayer printed wiring board.

(Actions of the Invention) By adopting the above-mentioned means, the present invention has the following effects.

In the process of forming blind via holes, drilling using a trill is not performed, so it has become famous for forming non-through holes of appropriate depth regardless of board thickness.

Since the outer layer base material is plated at the same time as the plating inside the blind via hole, the thickness of the conductor circuit of the outer layer base material 1 can be set arbitrarily.

(Example) First, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG.
) was patterned by a known method, 81 metal layers were heat-pressed through glass epoxy prepreg, and the 4-layer board patterned by a known method was then made into an inner layer substrate (
Used as 1). On both sides, an adhesive layer (2) with a thickness of 100 gm was transferred using a roll coater, and then a metal layer (3) with a thickness of 18 gm was bonded with heat and pressure on both sides of the multilayer board (4).
).

Next, as shown in FIG. 2, the metal layer (3
) was removed to a circular shape with a diameter of 0.41 to expose the adhesive layer (2), and then the exposed adhesive layer (2) was etched with a permanganate-based etching solution to remove the internal layer pattern (6). ) to expose.

Thereafter, a through hole (8) to be a through hole is drilled at a predetermined position as necessary, and known chemical steel plating and electrolytic copper plating are applied to the exposed inner layer pattern (6) and the outer layer metal. The multilayer substrate (4) is electrically connected to the layer (3) and then etched.
) blind through holes (7) and outer layer patterns (10) were formed to obtain a 6R multilayer printed wiring board according to the present invention as shown in FIG.

(Effects of the Invention) As described in detail below, the present invention provides a method for manufacturing a multilayer printed wiring board characterized by including at least the first steps (a) to (f).

(a) Step of patterning the inner layer substrate: (b) Step of forming a metal layer on the inner layer substrate via an adhesive layer: (c) Step of removing the metal layer at a desired position: (d) This metal Remove the adhesive layer exposed by layer removal,
A step of exposing a desired inner layer pattern: (e) A step of electrically connecting the exposed inner layer pattern to the metal layer by at least chemical copper plating; (f) A step of forming an outer layer pattern. Since a printed wiring board is formed, it is possible to provide a manufacturing method that can easily mass-produce multilayer printed wiring boards having blind via holes.

[Brief explanation of the drawing]

if< is a partially enlarged cross-sectional view of a multilayer board with the metal layer removed at the position where a blind via hole is to be formed. FIG. 2 is a partially enlarged cross-sectional view showing the state where the exposed contact M layer has been removed. FIG. 2 is a partially enlarged sectional view showing a completed printed wiring board. Explanation of symbols 1...Inner layer substrate, 2...Adhesive layer, 3...Metal layer,
4... Multilayer board, 5... Hole, 6... Inner layer pattern, 7... Blind via hole, 8... 1 through hole (which should be a through hole), 9... Metal plating, io
-... Outer layer pattern. Patent applicant: IBIDEN Co., Ltd. Figure 1 Figure 3

Claims (1)

Claims: A method for manufacturing a multilayer printed wiring board, comprising at least the following steps (a) to (f). (a) Step of patterning the inner layer substrate; (b) Step of forming a metal layer on the inner layer substrate via an adhesive layer; (c) Step of removing the metal layer at a desired position; (d)
A step of removing the adhesive layer exposed by this metal layer removal and exposing a desired inner layer pattern; (e) A step of electrically connecting the exposed inner layer pattern and the metal layer by applying at least chemical copper plating; (f) Step of forming an outer layer pattern.