JPH1168313A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board capable of substantially reducing interference and electrostatic induction noise from the outside and being manufactured without complicating work processes by a conventional manufacturing device. SOLUTION: In this multi-layer printed wiring board 20 provided with the circuit pattern of a signal line and the circuit pattern of a ground line or a power supply line, a signal line circuit pattern layer 17 is provided by forming the circuit pattern of the signal line on an insulating substrate 11 and forming the circuit pattern of the ground line or the power supply line so as to hold the signal line there between and the signal line circuit pattern layer 17 other than the circuit pattern of the ground line or the power supply line is covered with the insulation layer 16 of insulating resin or the like. Then, the insulation layer 16 covering the circuit pattern of the signal line is surrounded by a shielding layer 18 connected to the circuit pattern of the ground line or the power supply line and composed of plating, copper foil or conductive resin or the like and the periphery of the respective signal lines is turned to a pseudo coaxial structure.

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, and more particularly to a printed wiring board having excellent high frequency characteristics and good noise resistance.

[0002]

2. Description of the Related Art In recent years, as the density of integrated circuits has increased, multilayer printed wiring boards have been used as printed wiring boards in order to increase the number of signal line circuit pattern layers.

FIG. 3 shows an example of this multilayer printed wiring board.

As shown in FIG. 3, a conventional multilayer printed wiring board 10 includes a copper foil pattern layer 2 such as a ground line or a power supply line on both sides of a substrate (prepreg, thermosetting resin) 1 serving as an insulating layer. A copper foil pattern layer 5 of a signal line circuit pattern is laminated on a copper foil pattern layer 2 such as a ground line or a power supply line via an insulating layer 4.

As described above, in the conventional multilayer printed wiring board 10, the copper foil pattern layers 5 of the signal line circuit patterns formed on both sides of the board 1 are sandwiched between the copper foil pattern layers 2 such as ground lines or power supply lines. They are stacked in a strip line structure, thereby realizing necessary characteristic impedance and reducing interlayer crosstalk.

[0006]

However, in this type of printed wiring board 10, the speed of components to be mounted is increased, and when the mounting density is increased, the electromagnetic coupling between signal lines becomes dense. It is susceptible to noise and crosstalk due to electrostatic induction and electromagnetic induction, and the characteristic impedance of the signal line becomes non-uniform due to the influence of signal lines, wiring patterns and components laid in the vicinity. A reflected wave is generated in a signal flowing through the circuit, and this causes a malfunction during the circuit operation.

Further, since the printed wiring board itself has no shielding layer, it is susceptible to external noise such as electrostatic induction from the outside. Therefore, it is necessary to mount a conductive shield case or the like to shield external noise. Was.

As a method for solving the above problems, a multi-wire circuit board using a micro coaxial cable has been proposed in place of a conventionally used printed circuit board. Wiring is difficult and the wiring board tends to be expensive, which is not practical.

Further, Japanese Patent Application Laid-Open Nos. Hei 5-191056, Hei 1-163370 and Hei 7-212 are disclosed.
As proposed in Japanese Patent No. 043/043, signal lines are
A printed wiring board surrounded by a planar pattern of a power supply line and a ground line via an insulating layer is known, but the configuration is complicated and the number of work steps is increased, or the conventional printed wiring board manufacturing apparatus cannot manufacture the printed wiring board. However, there is a disadvantage that the cost is increased.

In view of the above, the present invention has been made in view of the above-mentioned circumstances, and the signal line has a pseudo-coaxial structure, so that interference and external static induction noise can be greatly reduced, It is an object of the present invention to provide a printed wiring board which can be manufactured using a printed wiring board manufacturing apparatus without complicating work steps.

[0011]

In order to solve the above problems, the present invention provides a multilayer printed wiring board having a circuit pattern of a signal line and a circuit pattern of a ground line or a power supply line. A signal line circuit pattern layer is provided by forming a circuit pattern of the ground line or the power supply line so as to sandwich the signal line and a signal line other than the circuit pattern of the ground line or the power supply line. After covering the circuit pattern layer with an insulating layer such as an insulating resin, connect the insulating layer covering the circuit pattern of the signal line to the circuit pattern of the ground line or power supply line, and perform plating, copper foil, or conductive resin. A pseudo coaxial structure is formed around each signal line by being surrounded by a shielding layer made of the same.

According to a second aspect of the present invention, there is provided a multi-layer printed wiring board having a circuit pattern of a signal line and a circuit pattern of a ground line or a power supply line, the two substrates having conductive layers formed on both surfaces of an insulating substrate. After forming a planar pattern of a ground line or a power supply line in an inner layer, the insulating layer is sandwiched therebetween, and the outer conductive layer of the substrate core material is etched or the like to form the signal line and the signal line. After forming a signal line circuit pattern layer of the ground line or the power line arranged to sandwich the signal line, after covering the signal line circuit pattern layer other than the circuit pattern of the ground line or the power line with an insulating layer such as an insulating resin, Connect the insulating layer covering the signal line circuit pattern to the ground line or power line circuit pattern, surround it with a shielding layer made of plating, copper foil or conductive resin, etc. It is obtained by a coaxial structure.

According to the above arrangement, the signal lines are arranged on the insulating substrate, and the insulating resin covering the signal lines other than the circuit patterns of the ground lines or the power supply lines arranged so as to sandwich the circuit pattern to be the signal lines. In addition, by connecting to the circuit pattern of the ground line or the power supply line, by forming a pseudo coaxial structure surrounded by a shielding layer of a planar pattern made of copper foil or conductive resin, etc.
The impedance of the signal lines can be reduced, and interference due to electromagnetic induction between the signal lines can be prevented.

[0014] Further, in order to cover the surface of the insulating substrate with a planar pattern of a ground line or a power supply line, and to shield adjacent signal lines with a circuit pattern of the ground line or the power supply line, these patterns are used. It plays the role of electrostatic shielding and greatly reduces external static induction noise.

Further, by adopting such a configuration, a circuit pattern of a ground line or a power supply line arranged so as to sandwich a circuit pattern to be a signal line is formed by a conventional apparatus for manufacturing a printed wiring board. The step of covering the circuit pattern of the signal line other than the circuit pattern of the ground line or the power supply line with the insulating resin or the like arranged so as to sandwich the signal line is the same operation as the conventional solder resist process,
It can be manufactured with a conventional printed wiring board manufacturing apparatus. In addition, a pseudo-coaxial structure is easily formed on the insulating resin covering the signal lines, surrounded by a shielding layer of a planar pattern made of copper foil or conductive resin connected to the circuit pattern of the ground line or the power supply line. it can. Instead of forming the shielding layer by applying a conductive resin, a copper foil layer may be formed by electroless copper plating or the like.

[0016]

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of a main part of a printed wiring board according to the present invention.

As shown in FIG. 1, a printed wiring board 20 according to the present invention is formed by laminating an insulating layer and a conductive layer in multiple layers. 17s has the signal line circuit pattern layer 17 formed with the circuit pattern 17g of the ground line or the power supply line interposed therebetween.

Specifically, the printed wiring board 20 is provided on both sides of an insulating substrate (prepreg, thermosetting resin) 11.
Ground line or power line planar pattern 12, prepreg (thermosetting resin) 15, signal line circuit pattern layer 17, insulating layer 16 such as insulating resin, shielding layer 18 such as plating or copper foil or conductive resin, And the insulating layer 14 are sequentially laminated.

Then, prepreg (thermosetting resin) 1
5. The signal line circuit pattern layer 17, the insulating layer 16, and the shielding layer 18 are covered so that the signal lines of the signal line circuit pattern layer 17 are surrounded by the insulating layer 16, and the signal line circuit pattern layer 17 And is covered with the shielding layer 18 so as to form a pseudo coaxial structure around the circuit pattern 17s of the signal line.

Next, a method of manufacturing the printed wiring board 20 having the pseudo coaxial structure will be described.

In manufacturing the printed wiring board 20 according to the present invention, a copper foil layer is formed by attaching copper foil to both sides of the board 11 and the copper foil layer (inner layer) on the surface of the board 11 is formed.
After the planar pattern 12 of the power supply line is formed on the copper foil layer on the back surface and the planar pattern 12 of the ground line is formed, the prepreg 14 is formed on each of the planar patterns 12 and 12.
Then, the copper foil layer (outer layer) is provided by pressing through an adhesive. Instead of forming a copper foil layer (inner layer) on the surface of the substrate 11, a substrate core material 13 having a copper foil layer formed on both surfaces of the substrate 11 in advance may be used.

Then, on the outer layer copper foil, a circuit pattern 17s of a signal line and a circuit pattern 17g of a ground line or a power supply line arranged so as to sandwich the signal line are formed by etching or the like.

Further, the circuit pattern 17s of the signal line other than the circuit pattern 17g of the ground line or the power supply line sandwiching the signal line is covered with the insulating layer 16. The process of forming the insulating layer 16 is the same as the conventional solder resist process, and can be manufactured by a conventional printed circuit board manufacturing apparatus.

Then, on the insulating layer 16 covering the signal lines,
By connecting to the circuit pattern 17g of the ground line or the power supply line and surrounding it with the planar pattern shielding layer 18, the insulating layer 16 and the shielding layer 18 are sequentially laminated around each signal line to form a pseudo coaxial structure. Printed wiring board 20 is manufactured.

With this pseudo coaxial structure, the impedance of the signal lines can be reduced, and interference between the signal lines due to electromagnetic induction can be prevented.

Further, in order to cover the surface of the insulating substrate 11 with a planar pattern of a ground line or a power supply line and to shield adjacent signal lines with a planar pattern of a ground line or a power supply line. The planar pattern serves as an electrostatic shield and greatly reduces external electrostatic induction noise.

Next, another embodiment will be described with reference to FIG.

As shown in FIG. 2, in a printed wiring board 30 of another embodiment, a board (prepreg) 11 is provided with two board core materials 13 each having a copper foil layer formed on both sides thereof, and grounds are respectively provided in inner layers. After the planar pattern 12 of the wire or the power supply line is formed, press forming is performed with the prepreg 15 interposed therebetween, and the copper foil layer serving as the outer layer of the substrate core material 13 is etched so as to sandwich the signal line and the signal line. The signal line circuit pattern layer 17 of the arranged ground line or power supply line is formed. An insulating layer 16 is laminated on the circuit pattern of the signal line of the signal line circuit pattern layer 17 in the same manner as the above-described printed wiring board 20, and a ground line or a ground line is further formed on the insulating layer 16. The shielding layer 18 having a planar pattern made of plating, copper foil, conductive resin or the like is connected to the pattern of the power supply line, and the circuit pattern of the signal line has a pseudo-coaxial structure.

That is, in the present embodiment, the signal line circuit pattern layer 17 is formed on the pre-plug 15 via the planar pattern 12 of the ground line or the power supply line. If it is on a layer, it may be formed directly on the substrate 11.

As described above, when the substrate core material 13 in which the copper foil layers are formed on both surfaces of the substrate 11 is used, the signal can be easily formed by configuring the printed wiring board 30 according to another embodiment. The line circuit pattern layer 17 can be formed, and a pseudo coaxial structure can be formed around the signal line.

In this embodiment, the power supply line is formed on one surface of the substrate (prepreg) 11 and the ground line is formed on the other surface. It may be.

The surface of the copper foil pattern layer 12 on which the ground lines and the power lines are formed may also serve as a component mounting surface or a solder mounting surface.

[0034]

In summary, according to the present invention, each signal line is shielded by the shielding structure of the printed wiring board, so that the characteristic impedance of the signal line can be made small and uniform. As a result, the amount of reflected waves in the current flowing through the signal lines is reduced, and electromagnetic interference between the signal lines on the printed wiring board can be reduced. Furthermore, external static induction noise,
Electromagnetic interference can be significantly reduced.

In addition, according to the present invention, the shielding layer can be formed by a conductive resin or the like in addition to the copper plating and the conductive paste.

Further, according to the present invention, the number of insulating layers is smaller than that of the above-mentioned conventional printed wiring board, and the structure is simple. There is an advantage that it can be manufactured without using.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part showing an example of a conventional printed wiring board.

[Explanation of symbols]

Reference Signs List 11 Insulating substrate (prepreg, thermosetting resin) 12 Planar pattern layer of ground line or power line 14 Insulating layer 15 Prepreg (thermosetting resin) 16 Insulating resin layer (resist layer etc.) 17 Ground line or power line Signal line circuit pattern layer including: 18 shielding layer of plating or conductive paint 20 printed wiring board

Claims (2)

[Claims] In a multilayer printed wiring board having a circuit pattern of a signal line and a circuit pattern of a ground line or a power supply line, a circuit pattern of the signal line is formed on an insulating substrate and the signal line is sandwiched therebetween. A signal line circuit pattern layer is formed by forming a circuit pattern of the ground line or the power supply line on the other, and a signal line circuit pattern layer other than the circuit pattern of the ground line or the power supply line is covered with an insulating layer such as an insulating resin. Then, the insulating layer covering the circuit pattern of the signal line is connected to the circuit pattern of the ground line or power supply line, and is surrounded by a shielding layer made of plating, copper foil, conductive resin, or the like, and the surroundings of each signal line are simulated. A printed wiring board having a coaxial structure. 2. A multi-layer printed wiring board having a circuit pattern of a signal line and a circuit pattern of a ground line or a power supply line, wherein two substrate core members each having a conductive layer formed on both surfaces of an insulating substrate, After forming a planar pattern of a ground line or a power supply line on the inner layer, the insulating layer is sandwiched therebetween, and the conductive layer serving as the outer layer of the substrate core material is etched or the like and arranged so as to sandwich the signal line and the signal line. After forming the signal line circuit pattern layer of the ground line or the power line, and covering the signal line circuit pattern layer other than the circuit pattern of the ground line or the power line with an insulating layer such as an insulating resin, the circuit of the signal line is formed. The insulating layer covering the pattern was connected to the circuit pattern of the ground line or power supply line, surrounded by a shielding layer made of plating, copper foil, conductive resin, etc., to form a pseudo-coaxial structure around each signal line. And a printed circuit board.