JPH04314380A - Printed wiring board - Google Patents

Abstract

PURPOSE:To provide a printed wiring board which realizes high density and enables sure exclusion of crosstalk noise. CONSTITUTION:A through-hole 4 which is coated with a conductive substance 5 is provided to an inner wall between circuit conductors 3. An interval of the through-hole 4 is set to 4 to 10mm and the through-hole 4 is connected to a power source circuit 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board with excellent resistance to crosstalk noise.

0002

2. Description of the Related Art Crosstalk usually refers to when a signal is sent to one side of adjacent signal lines, but the signal leaks to the other side. In other words, a phenomenon that causes electrical energy coupling between signal lines is called crosstalk. For example, it refers to mutual interference between telephone signals, or mutual interference between left and right channels in audio equipment.

[0003] Recently, with the development of digital equipment, the phenomenon of signal interference between circuit conductors formed on wiring boards has been observed, and reducing this crosstalk noise is a major factor that determines the performance of the circuit. This is a contributing factor.

[0004] This crosstalk noise is divided into two types: capacitive noise that occurs as a result of coupling due to electrostatic capacitance formed from the physical shape of adjacent conductors, and capacitive noise that occurs as a result of coupling between adjacent conductors due to electrostatic capacitance formed from the physical shape of the circuit. Therefore, there is a dielectric type that occurs when a change in the magnetic field generated between a signal line and a ground line crosses another signal line and a ground line.

[0005] As shown in Japanese Patent Application Laid-Open No. 53-5769, a printed wiring board that is excellent against such crosstalk noise is one in which a conductor pattern with high input/output impedance of an electronic circuit is replaced with a ground line pattern. Some are characterized by being sandwiched.

[0006] In particular, this is designed to block crosstalk noise by sandwiching the crosstalk noise between ground lines in the same layer.

[0007]

[Problem to be Solved by the Invention] However, in the case of a structure in which a conductor pattern is sandwiched between the ground line patterns, the crosstalk shielding effect is limited to the conductor on the same layer sandwiched between the ground line conductor patterns. Limited to patterns.

[0008] Therefore, when shielding crosstalk noise in a multilayer wiring board, it is necessary to set a ground line for shielding crosstalk noise for each layer, which takes up a lot of wiring space, making it difficult to achieve high density. There was a problem in that it was a big hindrance.

Furthermore, even in the case of a single-layer wiring board, since one conductor pattern is sandwiched between two ground lines, a large amount of wiring space is taken up, which is a problem in that it hinders high density.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a printed wiring board that achieves high density and suppresses the generation of crosstalk noise. There is a particular thing.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a through hole whose inner wall is coated with a conductive material between adjacent circuit conductors, and connects the through hole to a power supply circuit or It has a structure that is electrically connected to a grounding circuit.
The structure of the conductor that shields crosstalk is characterized by a cylindrical structure that penetrates between layers.

Furthermore, the printed wiring board according to the present invention has the following features:
Between adjacent circuit conductors, through holes that do not contact the circuit conductors, penetrate the insulating layer, and whose inner walls are coated with a conductive material are provided at intervals of 10 mm or less between the centers of the through holes, and the conductive material in the through holes is provided. is electrically connected to a power supply circuit or a ground circuit.

The center spacing of the through holes is preferably 4 mm or more and 10 mm or less. If the center spacing of the through holes exceeds 10 mm, crosstalk noise will rise rapidly, and when used as a high frequency circuit, malfunctions due to crosstalk noise may occur. more likely to occur.

[0014]

[Function] As is clear from the above configuration, since the conductor that shields crosstalk noise penetrates each layer, it is possible to shield the crosstalk noise of each layer all at once, and the crosstalk noise is shielded with high density. A printed wiring board with excellent effects can be obtained.

[0015]

Embodiments Hereinafter, embodiments of the printed wiring board according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are cross-sectional views of a printed wiring board showing a first embodiment of the present invention, and FIGS. 3 and 4 are cross-sectional views of a printed wiring board showing another embodiment of the present invention.

1 and 2, this printed wiring board 1 has a desired pattern of circuit conductors 3 formed on the surface of an insulating layer 2, and through holes 4 are formed between adjacent circuit conductors 3. The inner wall of the through hole 4 is coated with a conductive material 5, and the conductive material 5 is electrically connected to a power supply circuit 6 inserted into the insulating layer 2.

Further, as shown in FIG. 2, adjacent through holes 4, 4 are electrically connected by a signal pattern 7.

Next, to briefly explain the manufacturing process of this printed wiring board 1, first, an etching resist is formed on a base material in which metal foil is laminated on both sides of an insulating board.
Power and ground patterns are formed on only one side by etching.

Next, the prepreg is layered on the surface on which the power supply and ground patterns are formed, and then metal foil is layered and molded by heating and pressing. Next, a through hole 4 penetrating the entire layer is formed between the positions where the signal pattern is to be formed. The hole is opened and the inner wall and surface layer of the hole are coated with a conductive material 5. Thereafter, an etching resist is formed on the surface layer, and a signal pattern 7 is formed by etching.

[0021] Examples of the resin for the insulating plate and prepreg used in the present invention include epoxy resin, phenol resin, and polyimide resin. The resins for the insulating plate and the prepreg are not necessarily limited to the same resin.

[0022] Methods for forming the through hole 4 include punching, drilling, laser processing, etc.
From the viewpoint of workability and cost, it is preferable to use a drilling method.

Furthermore, methods for forming the conductive substance 5 in the through holes 4 include wet plating methods such as electroless plating and electrolytic plating, dry plating methods such as evaporation and sputtering, conductive paste, etc. Although there are hole-filling methods using , wet plating methods are preferred from the viewpoint of workability.

In the printed wiring board 1 according to the present invention, the through hole 4 whose inner wall is covered with a conductive material 5 penetrates the insulating layer 2 as a conductor for shielding crosstalk noise between the circuit conductors 3. The conductive material 5 covering the holes 4 can block crosstalk noise of the insulating layer 2 all at once, which is advantageous in that a high-density printed wiring board with excellent signal characteristics can be obtained.

Furthermore, the setting intervals of the through holes 4 are as shown in FIG.
As is clear from the graph shown in , it is easy to understand that a range of 4 mm to 10 mm is desirable, and that if the distance between the through holes 4 is less than 4 mm or exceeds 10 mm, the crosstalk noise will increase. .

Next, FIGS. 3 and 4 show another embodiment of the printed wiring board 1 according to the present invention, and the one in FIG. The power supply and ground patterns are formed on only one side by etching.

Next, the prepreg is layered on the surface on which the power supply and ground patterns are formed, and then metal foil is layered and molded by heating and pressurizing. Next, a through hole 4 penetrating through the entire layer is formed between the positions where the signal pattern is to be formed. The hole is opened and the inner wall and surface layer of the hole are coated with a conductive material 5. Thereafter, an etching resist is formed on the surface layer, and a signal pattern is formed by etching.

[0028] Further, prepreg may be stacked on both sides of the fabric, metal foil may be further stacked and molded by heating and pressing, an etching resist may be formed on the metal foil, and a conductive pattern may be formed by etching.

Next, as shown in FIG. 4, an etching resist is formed on the base material in which metal foil is pasted on both sides of the insulating plate, and by etching, a power supply and ground pattern is formed on one side, and a signal pattern is formed on the other side. Form.

Next, a prepreg is layered on the surface on which the signal pattern is formed, and then a metal foil is layered and heated and pressed to form the structure. A prepreg is placed on the side on which the power supply and ground patterns are formed, and then the signal pattern side of the substrate on which the signal pattern is formed on only one side is placed on top of the other side, and then heated and pressed to form the product.

Next, a through hole 4 passing through only the signal layer is formed between the signal patterns, and the inner wall of the hole and the surface layer are covered with a conductive material 5. Furthermore, an etching resist may be formed on this, and a conductive pattern may be formed by etching.

[0032] The hole drilling method used in this case is
It is preferable to use a laser machining method in that it does not penetrate the ground pattern.

Next, specific embodiments of the printed wiring board of the present invention will be described in detail. [Example 1] Etched resiston 1010 (trade name, manufactured by DuPont) was formed on only one side of a copper-clad laminate MCL-E168 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and a power supply and ground pattern were formed by the subtract method. Prepreg GEA-1 is formed only on this power supply and ground pattern surface.
68N (trade name, manufactured by Hitachi Chemical Co., Ltd.), and on top of that, a copper foil JTC (trade name, manufactured by Nippon Denki Co., Ltd., thickness 18 μm) for copper-clad laminates, and the heating plate temperature was 170°C. ,
They were laminated and integrated by heating and pressing at a molding pressure of 7.85×10 6 Pa for 70 minutes.

Next, a through hole is made by drilling between the signal pattern formation positions, and catalyst HS201 (trade name manufactured by Hitachi Chemical Co., Ltd.) is applied to the inner wall and surface layer of the hole, and electroless plating solution Cust201 is applied to the inner wall and surface layer of the hole. (Hitachi Chemical Co., Ltd.)
Copper plating (35 μm) was performed using a copper pyrophosphate plating solution. Next, an etching resiston 1010 (trade name manufactured by DuPont) is formed on this, and a pattern is formed by the tenting method so that the signal pattern and each through hole are not connected by the surface circuit, resulting in the structure shown in FIG. A printed wiring board 1 was obtained.

The conductor width in this printed wiring board 1 is 0.
12mm, conductor spacing 1.5mm, through hole inner diameter 0.
5 mm, and the center spacing of the through holes is 8 mm. In the surface layer of the obtained printed wiring board 1, the circuit conductor 3 of the printed wiring board 1 is connected to the guiding wire 8 and the guided wire 9 shown in FIG.
The crosstalk noise was measured by applying a current of 1 GHz and found to be 2.8%. In addition, Figure 6
Reference numeral 10 indicates a pulse generator, and reference numeral 11 indicates a synchroscope.

On the other hand, when the conductor width, conductor spacing, and through-hole inner diameter are the same as those of the printed wiring board 1, and the through-hole center spacing is 10 mm, the crosstalk noise is 3.
．． The crosstalk noise was 7.8% when the through-hole center spacing was 12 mm.

Further, when the conductor width, conductor spacing, and through-hole inner diameter are the same as those of the printed wiring board 1, and the through-hole center spacing is 4 mm, the crosstalk noise is 2.
．． 4%, the crosstalk noise when the through-hole center spacing is 3.5mm is 8.8%, and the crosstalk noise is 15 when the through-hole center spacing is 3.0mm.
．． It was 1%.

Therefore, the center spacing of the through holes is as shown in FIG.
As is clear from the graph, a range of 4 mm to 10 mm is suitable. [Example 2] When forming the circuit pattern on the surface of the board produced in Example 1, a signal pattern 7 was formed to connect each through hole, and a printed wiring board 1 having the structure shown in FIG. 2 was obtained. .

[0039] Conductor width: 0.13 mm, conductor spacing: 1.5 mm
The crosstalk noise was measured in the same manner as in Example 1 on the surface layer of the printed wiring board 1 in which the inner diameter of the through holes was set to 0.5 mm and the center spacing of the through holes was set to 8 mm. As a result, the crosstalk noise was 2.4%. Ta. [Example 3] Etched resiston 1010 (trade name, manufactured by DuPont) was formed on only one side of a copper-clad laminate MCL-E168 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and a power supply and ground pattern were formed by the subtract method. Prepreg GEA-1 is formed only on this power supply and ground pattern surface.
68N (trade name, manufactured by Hitachi Chemical Co., Ltd.), and on top of that, a copper foil JTC (trade name, manufactured by Nippon Denki Co., Ltd., thickness 18 μm) for copper-clad laminates, and the heating plate temperature was 170°C. ,
They were laminated and integrated by heating and pressing at a molding pressure of 7.85×10 6 Pa for 70 minutes.

Next, a through hole penetrating the entire layer is formed between the signal pattern formation positions by drilling, and the inner wall of the through hole and the surface layer are subjected to electroless plating pretreatment HS201 (trade name, manufactured by Hitachi Chemical Co., Ltd.). ), electroless plating Cust20
1 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and was further plated with copper (35 μm) using a copper pyrophosphate plating method.

After that, the etching resist strip 10
10 (trade name, manufactured by DuPont), and a signal pattern was formed by the tenting method. Furthermore, on top of this, prepreg GEA-168N (trade name manufactured by Hitachi Chemical Co., Ltd.)
Then, on top of that, copper foil JTC (trade name, manufactured by Nippon Denki Co., Ltd., thickness 18 μm) for copper-clad laminates was layered, and the heating plate temperature was 170°C and the molding pressure was 7.85 × 10 6 Pa to 70°C.
They were laminated and integrated by heating and pressurizing for a minute.

Next, the etching resist stone 101
0 (trade name manufactured by DuPont) and a signal pattern was formed by the subtract method to obtain a printed wiring board 1 having the structure shown in FIG. 3.

[0043] The conductor width of this printed wiring board 1 is 0.12 m.
m, conductor spacing 1.2mm, through hole inner diameter 0.3mm
, the through-hole center spacing was set to 7 mm, and Fig. 6
Applying the circuit conductor 3 to the guiding wire 8 and guided wire 9 shown in
The crosstalk noise was measured and found to be 2.6%. [Example 4] Prepreg GEA-168N (trade name manufactured by Hitachi Chemical Co., Ltd.) is layered on both sides of the substrate produced in Example 1 before drilling, and copper for copper-clad laminates is further layered on top of it. Foil JTC (product name manufactured by Nippon Denki Co., Ltd., thickness 18
μm), heating plate temperature 170℃, molding pressure 7.85×
They were laminated and integrated by heating and pressing at 10 6 Pa for 70 minutes.

After that, carbon dioxide laser (Hitachi, Ltd.)
(manufactured by Co., Ltd.) was used to obtain a hole that reached the power supply and ground patterns in the inner layer and did not penetrate between the signal pattern formation positions.

Next, the inner wall and surface layer of the through hole were subjected to electroless plating pretreatment HS201 (trade name, manufactured by Hitachi Chemical Co., Ltd.).
, electroless plating Cust201 (trade name manufactured by Hitachi Chemical Co., Ltd.), and copper plating (3) using copper pyrophosphate plating method.
5 μm).

Thereafter, an etching resiston 1010 (trade name, manufactured by DuPont) was formed thereon, and a signal pattern was formed by a tenting method, thereby obtaining a printed wiring board 1 having the structure shown in FIG. 4.

[0047] The conductor width of this printed wiring board 1 is 0.18 m.
m, conductor spacing 1.5mm, through hole inner diameter 0.7mm
, the center spacing of the through holes is set to 10 mm, and the circuit conductors 3 are arranged on the surface layer of the printed wiring board 1 as shown in FIG.
The crosstalk noise was measured by applying the crosstalk noise to 8 and 9 shown in FIG. 8, and the result was 2.8%.

[0048]

Effects of the Invention As explained above, the printed wiring board according to the present invention has through holes whose inner walls are coated with a conductive material between circuit conductors at intervals of 4 to 10 mm, and these through holes are connected to the power supply circuit or the ground. By connecting to a circuit and forming a conductor that shields crosstalk noise through the insulating layer, crosstalk noise in each layer of the insulating layer can be shielded all at once.

[0049] Therefore, it is possible to obtain a printed wiring board with excellent wiring space, high density, reliable shielding of crosstalk noise, and high density and excellent signal characteristics.

[Brief explanation of drawings]

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

FIG. 2 is a partially cross-sectional perspective view of a printed wiring board showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a printed wiring board showing an embodiment in which the through-hole of the present invention penetrates only between an outer layer and an inner layer.

FIG. 4 is a cross-sectional view of a printed wiring board showing an embodiment in which a through hole of the present invention penetrates only an inner layer.

FIG. 5 is a diagram showing the relationship between the center spacing of through holes provided between adjacent circuit conductors and crosstalk noise according to the present invention.

FIG. 6 is a circuit diagram of a circuit used for measuring crosstalk noise according to the present invention.

[Explanation of symbols]

1 Printed wiring board 2 Insulating layer 3 Circuit conductor 4 Through hole 5 Conductive substance 6 Power supply circuit 7 Signal pattern 8 Guide wire 9 Guided line 10 Pulse generator 11 Synchronoscope

Claims (3)

[Claims] Claim 1: Through holes whose inner walls are coated with a conductive material are provided between adjacent circuit conductors at intervals of 4 mm to 10 mm, and the through holes are electrically connected to a power supply circuit or a ground circuit. A printed wiring board characterized by being connected. (2) The through holes adjacent to each other are electrically connected to each other by a circuit pattern (1).
The printed wiring board described. 3. The printed wiring board according to claim 1, wherein the through hole penetrates only between the inner layers or between the outer layer and the inner layer.