JPH05175663A - Multilayer wiring board - Google Patents

Abstract

PURPOSE:To reduce an external moise and a self noise with reference to a wiring at board and to increase an interconnection capacity. CONSTITUTION:In a multilayer wiring board, a power supply layer 1, a grounding layer 2 and pads 4 for component connection use exist on the same planes at outermost layers, two or more signal layers 3(a) to 3(d) exist in inner layers, buried holes 6(a), 6(b) which connect the inner layers are provided, and blind holes 5 which connect the land parts 4(a) at the outermost layers to the inner- layer signal layer 3(a) or 3(b) are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board.

[0002]

2. Description of the Related Art A conventional multilayer wiring board is constructed by connecting a plurality of signal layers, power supply layers or ground layers with via holes. In recent years, reduction in external noise and prevention of self-noise on the wiring board have become particularly important in terms of reliability as the speed and the voltage of the elements mounted on the wiring board become higher. In order to reduce the external noise and the self-noise, as disclosed in Japanese Patent Laid-Open No. 64-89585, an insulating layer is formed on both sides of a penetrating double-sided wiring board with a via hole, and then a conductive paste is formed. There is a wiring board in which an outer shield layer is formed by copper plating.

[0003]

Problems to be Solved by the Invention JP-A-64-8958
Although the method disclosed in Japanese Patent Publication No. 5 has the effect of reducing external noise and self-noise to the multilayer wiring board, the shield layer and the component connecting rides provided in the openings of the shield layer do not exist in the same plane, so that the shield is provided. There is a problem that it is difficult to use the layer itself as a land for component connection and an opening for connecting the inner layer and the shield layer is required, so that the wiring capacity of the multilayer wiring board cannot be increased. The present invention provides a wiring board that has a large amount of wiring accommodated and is excellent in the effect of reducing external noise and self-noise.

[0004]

The present invention will be described with reference to FIG. In the present invention, in a multilayer wiring board having a power supply layer (1), a ground layer (2), and two or more signal layers (3 (a) to 3 (d)), the outermost layer (1 or 2) is a power supply. It comprises a layer (1), a ground layer (2), and component connection pads (4 (a), 4 (b)) formed on the same plane as this layer. Both outermost layers (1 or 2) need to be power supply layers or ground layers, but both may be power supply layers or ground layers. Component connection pads (4 (a) or 4 (b)) are required in the outermost layer (1 or 2). The position may be any position as long as it is on the same plane as at least the power supply layer or the ground layer, and may be located only on one side. A part of the signal layer may be arranged in the outer layer (1 or 2), but the noise reduction effect is enhanced when 30% or more of the total surface area is composed of the power supply layer and the ground layer. Preferred for. Further, it is particularly preferable that 60% or more of the total surface quality is constituted by the power supply layer and the ground layer, because the noise reduction effect can be remarkably enhanced. Inner layer (3 (a) -3
(D)) needs to be composed of a signal layer,
In order to improve the wiring density, it is desirable that there is a buried hole (6 (a) or 6 (b)) connecting these signal layers. In the inner layer, one of the inner layers (3 (a) or 3 (d)) adjacent to the outermost layer (1 or 2) needs to include a signal layer, but the other inner layers include a signal layer and a power source. It may be the ground layer. Berido Hall is 6 (a)
As shown in FIG.
(B)) may be connected, or separate layers (for example, 3 (a) and 3 (d)) may be connected as shown in 6 (b). A blind hole (5) for connecting the outermost component connecting land (4 (a)) and the inner signal layer (3 (a) to 3 (d)) is required. This bridehole is
It is necessary to connect to at least the outermost layer component connecting land portion, but the position may be formed on the land, at an end portion of the land, or another land electrically connected to the outside of the land. However, since the wiring accommodation amount can be increased and the area of the outer layer power supply, the ground, or the land portion for noise reduction can be increased, it is preferable to be on the land or at the land end portion.

[0005]

In the present invention, since the power source or the ground is arranged in the outermost layer, noise can be reduced in the same manner as shown in Japanese Patent Laid-Open No. 64-89585, and the component connecting land and the power source or the ground layer are on the same plane. Therefore, since the power supply or the ground layer itself can be used as a land for connecting components, it is possible to increase the wiring accommodation amount. In addition, JP-A-64-
Since the opening for connecting the inner layer and the shield layer, which is required in Japanese Patent Publication No. 89585, is not necessary, the amount of wiring accommodated can be increased.

[0006]

EXAMPLES An example of a wiring board of the present invention will be described including an example of a manufacturing method. First, 0.2 mm thick MCL-E
-67 (Glass cloth / epoxy copper clad laminate, Hitachi Chemical Co., Ltd. product name), conventional drilling, 20 μm copper plating,
An etching resist is formed and etching is performed to form a double-sided wiring board with through holes having a desired pattern (see FIGS. 1, 3 (a), 3).
(B) layer) was obtained. In the same way (Fig. 1, 3 (c), 3
Another double-sided wiring board (to be the layer (d)) was obtained. The GE-67N (glass cloth /
Epoxy prepreg) was placed, and 18 μm copper foils were placed on the top and bottom of the epoxy prepreg, and the layers were adhered in a multilayer manner by heating / pressing in a conventional manner. After that, blind hole non-through holes (5) and through hole through holes (7) are formed by using a conventional drilling process.
Was processed. Finally, conventional 30 μm copper plating, etching resist formation and etching were performed to obtain a multilayer wiring board having the structure of the present invention. The outer layers (power supply, ground, pads) at this time are formed on the same plane on each surface,
Its thickness was 55 μm. Inner layer is 3 (a) -3
It was composed of a total of 4 signal layers of (d), and each had a thickness of 35 μm. The hole connecting the layers is 3 (a)
And the berid holes 6 (a), 3 connecting the layers 3 and 3 (b)
The buried holes 6 (a) connecting the layers (c) and 3 (d),
Blind hole 5 connecting layers 4 (a) and 3 (b)
It comprises a blind hole 5 connecting 4 (a) and 3 (d) and a through hole 7 penetrating all layers. Table 1 shows the wiring capacity and the noise level when the number of inner signal layers and the outer layer shield ratio (* 1) of the multilayer wiring board of the present invention are changed in comparison with the conventional multilayer wiring board.

[0007]

[Table 1] (* 1) The outer layer shield ratio is the value obtained by dividing the area of the outer power layer and the ground layer by the total area of the outer layer (%).

[0008]

As described above, according to the present invention, it is possible to provide a wiring board which has a large amount of wiring accommodated and is excellent in the effect of reducing external noise and self-noise.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer wiring board showing an embodiment of the present invention.

[Explanation of symbols]

1 Power Layer 2 Ground Layer 3 Signal Layer 4 Component Connection Land 5 Blind Hole 6 Verid Hole 7 Through Hole

Claims (2)

[Claims] 1. A multilayer wiring board having a power supply layer, a ground layer, and two or more signal layers, wherein the outermost layer is composed of a power supply layer or a ground layer and a component connection land formed on the same plane as this layer, and an inner layer. Is a signal layer, and has a blind hole connecting the outermost land portion and the inner signal layer. 2. The multilayer wiring board according to claim 1, wherein the signal layer of the inner layer is present in two or more layers and has a buried hole connecting the signal layers.