JP2000261150A - Multilayer printed wiring board and manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of electromagnetic wave to the outside in concentrated flow by providing a through hole connected to a ground layer coaxially to the outside of a signal through hole, and making radiation noise generated in signal current flow to a ground through hole by converting it to a return current. SOLUTION: A multilayer printed wiring board 1 has a four-layer structure with signal wirings 3, 4 arranged in front and rear surfaces of an insulation body 2 of resin, etc., and a ground layer 5 and a power supply layer 6 laminated in the insulation body 2. A signal through hole 7 is plated and made to pass through the insulation body 2 and connect the signal wirings 3, 4 and is formed tubular. Furthermore, a ground through hole 8 is plated to be connected to the ground layer 5 through the insulation body 2 outside the signal through hole 7 and is formed tubular. The ground through hole 8 has a clearance to the power supply layer 6 in the insulation body 2 and is not connected to the power supply layer 6. Electromagnetic wave generated in signal current flows concentrating to the through hole 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board for use in electronic equipment and the like and a method of manufacturing the multilayer printed wiring board, and more particularly, to suppressing radiation noise generated from signal through holes of the multilayer printed wiring board. Useful for

[0002]

2. Description of the Related Art FIG. 6 is a partial sectional view of a conventional multilayer printed wiring board. The multilayer printed wiring board 21 has a four-layer structure including signal wirings 23 and 24 arranged on the front and back surfaces of an insulator 22, and a ground layer 25 and a power supply layer 26 laminated between the insulators 22. The signal through hole 27 is formed in a cylindrical shape by plating so as to penetrate the insulator 22 and connect the signal wiring 23 and the signal wiring 24. Further, a ground through hole 28 and a power supply through hole 29 penetrate the insulator 22 and are formed in a cylindrical shape by plating. The ground through hole 28 is connected to the ground layer 25 and is not connected to the power supply layer 26. The power supply through hole 29 is not connected to the ground layer 25 but is connected to the power supply layer 26. The ground through hole 28 and the power supply through hole 29 are connected to a chip capacitance 30 in the upper layer in the drawing.

Next, the multilayer printed wiring board 21 having the above structure
Will be described. In the figure, the signal current TH and the return current TH generated by the signal current TH are indicated by arrows. The signal current TH flowing on the signal wiring 23 as shown by the arrow J flows through the signal through hole 27 as shown by the arrow K, is transmitted to the signal wiring 24, and flows on the signal wiring 24 by the arrow L
It is assumed that the flow is as follows. In this case, a return current TH in a direction opposite to the direction of the flow of the arrow M is generated in the power supply through hole 29 by an electromagnetic wave generated by the signal current TH on the signal through hole 27. This return current TH is transmitted through the chip capacitance 30 to the ground through hole 28 as shown by the arrow N, flows to the ground layer 5, and suppresses radiation noise generated by the signal current TH flowing to the signal through hole 27. It has become.

The signal current T flowing on the signal line 23 is
H is generated in the ground layer 25, the signal current TH flowing on the signal wiring 24 is generated in the power layer 26, and flows to the ground layer 25 through the power through hole 29, the chip capacitance 30, and the ground through hole 28, Radiation noise generated by the signal current TH flowing through the signal wirings 23 and 24 is suppressed.

[0005]

In the above-mentioned conventional multilayer printed wiring board, the signal current T flowing through the signal through-hole is provided.
The return current TH generated in the power supply through hole by H flows through the chip capacitance and the ground layer through the ground through hole to suppress radiation noise.

However, the above-mentioned conventional multilayer printed wiring board has a sufficient function in terms of direct current, but has a problem that it becomes a factor of increasing radiation noise for high-frequency signals. In other words, since the signal through-hole, the power supply through-hole and the ground through-hole are arranged at positions separated from each other, the electromagnetic waves generated by the currents radiating in opposite directions do not sufficiently cancel each other out. There is a problem of generating large radiation noise.

As a means for easily solving the above problem, a means for arranging a chip capacitance very close to a signal through hole can be designed.
One chip capacitance must be mounted on one signal through-hole, and there is a disadvantage that a large amount of wiring space is consumed.

[0008]

SUMMARY OF THE INVENTION The present invention provides at least two
One signal wiring layer and a ground layer and a power supply layer disposed between the two signal wiring layers are alternately stacked with an insulator interposed therebetween, and the signal wiring of one signal wiring layer and the signal wiring of the other signal wiring layer are stacked. In a multilayer printed wiring board that is connected to wiring with a signal through hole, a ground through hole connected to the ground layer is provided coaxially outside the signal through hole, and a signal current flows Radiation noise generated from the through hole is converted into a return current on the ground through hole, and the return current is caused to flow through the ground through hole. In addition, place an insulator between the ground through hole and the power supply layer,
It is preferable that the insulator has a function of a capacitance functioning as a capacitance between the ground layer and the power supply layer so that a high-frequency current can easily flow.

Further, according to the present invention, a conductor is laminated on both sides of an insulator on both sides by plating a hole on the conductor substrate, and then filling the insulator with the hole to form a through hole for ground. The conductor is a ground layer connected to the through hole for ground, the other conductor is a power supply layer, a double-sided conductor base manufacturing process, and a conductor base where the conductor is laminated on one side of the insulator so that the insulator contacts A multilayer board manufacturing process of forming a multilayer board by laminating through a prepreg on both sides of the both-side conductive base material, forming a hole coaxially passing through a ground through hole of the multilayer board, and plating the hole. A method of forming a signal through hole, and a signal wiring forming step of forming a signal wiring connected to the signal through hole. In the case of this manufacturing method, it is preferable that the conductor layer formed in the double-sided conductor base material manufacturing process be connected to the kisei capacitance due to the clearance between the conductor layer and the ground through hole.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited by this. FIG. 1 is a partial cross-sectional view of a multilayer printed wiring board according to an embodiment. FIG. 2 is a partially omitted perspective view of the multilayer printed wiring board according to the embodiment, in which an insulator is omitted and only a conductive portion is shown.

This multilayer printed wiring board 1 has four layers having signal wirings 3 and 4 arranged on the front and back surfaces of an insulator 2 such as a resin, and a ground layer 5 and a power supply layer 6 laminated between the insulators 2. It has a structure. In addition, the signal through hole 7 penetrates through the insulator 2 to form the signal wiring 3 and the signal wiring 4.
And is formed in a cylindrical shape by plating so as to connect them. Further, a ground through hole 8 is formed in a cylindrical shape by plating outside the signal through hole 7 via the insulator 2 so as to be connected to the ground layer 5. This ground through hole 8 is
Has a clearance between the power supply layer 6 and the power supply layer 6.
And not connected.

FIG. 3 is an explanatory view of a through hole, showing a state in the power supply layer 6. A ground through hole 8 is disposed outside the signal through hole 7 via the insulator 2, and a power supply layer 6 is located outside the ground through hole 8 via the insulator 2. Therefore, the signal through-hole 7 and the ground through-hole 8 have a so-called coaxial line structure, and a clearance exists between the ground through-hole 8 and the power supply layer 6.

Next, the operation of the multilayer printed wiring board 1 having the above structure will be described with reference to FIG. In FIG. 2, the signal current TH and the return current TH generated by the signal current TH are indicated by arrows. The signal current TH flowing on the signal wiring 3 as shown by the arrow A flows through the signal through hole 7 as shown by the arrow B, is transmitted to the signal wiring 4, and flows on the signal wiring 4 as shown by the arrow C. Suppose. In this case, the signal through hole 7 is provided in the ground through hole 8.
An electromagnetic wave generated by the upper signal current TH generates a return current TH in a direction opposite to the flow direction of the arrow B. This return current TH flows toward the ground layer 5 as indicated by arrows D and E, and flows in all directions on the ground layer 5 as indicated by arrows F, G, H and I.

When the current flowing through the signal through-hole 7 is a high frequency, the clearance between the ground through-hole 8 and the power supply layer 6 acts as a kisei capacitance. The return current TH is transmitted to the ground through-hole 8 with low impedance through the capacitance between the power supply layer 6 and the ground through-hole 8 with a clearance, and flows to the ground layer 25.

The signal current TH flowing on the signal wiring 3 is
Is generated in the ground layer 5, and the signal current TH flowing on the signal wiring 4 is generated in the power supply layer 6, and has a low impedance for ground through low capacitance through the clearance between the power supply layer 6 and the ground through hole 8. It is transmitted to the through hole 8 and flows to the ground layer 25.

Therefore, according to the multilayer printed wiring board 1 of the above embodiment, the electromagnetic wave generated by the signal current TH flows intensively inside the ground through hole 8 and does not leak to the outside. Radiated noise from the device can be reduced. Further, since it is not necessary to mount the chip capacitance on the surface as in the related art, the number of parts and the number of assembling steps can be reduced, and a multilayer printed wiring board with reduced radiation noise at low cost can be provided.

In this embodiment, the case where the number of signal wiring layers is two, that is, four, which is a ground layer and a power supply layer, has been described. Since the ground through hole can be formed in the same manner, the description of the case other than four layers is omitted. Next, the manufacturing process of the multilayer printed wiring board 1 having the above configuration will be briefly described with reference to the drawings. FIG. 4 is a flowchart of the manufacturing process, and FIG. 5 is an explanatory diagram of the manufacturing process according to the flowchart.

S1: As shown in FIG. 5A, a substrate is formed by laminating copper foil or copper clad plates 9, 10 (hereinafter abbreviated as copper) on both sides of the surface of the insulator 2. Although not shown, two sheets of copper laminated on one side of the surface of the insulator are formed in the same manner. S2: As shown in FIG. 5 (2), copper 9.1 on both sides of the surface
A hole 11 for forming a through hole is formed in the base material on which 0 is laminated.

S3: As shown in (3) of FIG. 5, the hole 11 is plated with copper or the like, and the base copper 10 is masked and etched to form the ground through hole 8. A donut-shaped groove 13 for forming a clearance between the power supply layer 6 and the power supply layer 6 is formed. S4: As shown in (4) of FIG.
Fill 4 The groove 13 is also filled with a resin 15. Thus, the ground layer 5, the power supply layer 6, and the ground through hole 8 are formed. It is preferable that the same resin 14 and 15 as the insulator 12 be used, but the resin is not limited to this.

S5: As shown in FIG. 5 (5), the substrate formed in S4 is laminated such that a substrate having copper laminated on one surface side in S1 is sandwiched with the copper side outside. At this time, a prepreg (not shown) enhances the adhesive effect of each layer. In the figure, reference numerals 16 and 17 are bonding surfaces. In addition, the prepreg is generally used,
It is made by impregnating glass fibers or the like with the same or different resin as the insulator. In addition, while performing the lamination process of S5, S5
4 may be performed.

S6: As shown in FIG. 5 (6), the resin 1
A hole 18 is made so as to penetrate through the hole 4. S7: As shown in (7) of FIG. 5, the surface copper is etched or the like to form signal wirings 3 and 4, and the holes 18 are plated with copper or the like to form signal through holes 7. Thus, the multilayer printed wiring board 1 is manufactured.

Therefore, the multilayer printed wiring board 1 for suppressing radiation noise can be easily manufactured by the above-described method for manufacturing a multilayer printed wiring board.

[0023]

As described above, according to the present invention, it is possible to obtain the effect that the electromagnetic waves generated by the signal current flowing through the signal through-hole are concentrated inside the ground through-hole and do not leak outside. For this reason, the effect of being able to provide a multilayer printed wiring board with suppressed radiation noise is obtained. Further, a manufacturing method for manufacturing the multilayer printed wiring board can be provided.

By providing ground through holes in all of the signal through holes formed in the multilayer printed wiring board, it is possible to provide a multilayer printed wiring board having a low high-frequency impedance at any position.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a multilayer printed wiring board according to an embodiment;

FIG. 2 is a partially omitted perspective view of the multilayer printed wiring board according to the embodiment;

FIG. 3 is an explanatory view of a through hole according to the embodiment;

FIG. 4 is a flowchart of a manufacturing process of the multilayer printed wiring board according to the embodiment;

FIG. 5 is an explanatory diagram of a manufacturing process of the multilayer printed wiring board according to the embodiment;

FIG. 6 is a partial cross-sectional view of a conventional multilayer printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer printed wiring board 2 Insulator 3 Signal wiring 4 Signal wiring 5 Ground layer 6 Power supply layer 7 Signal through hole 8 Ground through hole

Claims (4)

[Claims] At least two signal wiring layers and a ground layer and a power supply layer disposed between the two signal wiring layers are alternately stacked with an insulator interposed therebetween, and the signal wiring of one signal wiring layer is In a multilayer printed wiring board in which the signal wiring of the other signal wiring layer is connected by a signal through hole, a ground through hole connected to a ground layer is provided coaxially outside the signal through hole. A multilayer printed wiring board characterized in that radiation noise generated from a signal through-hole by current flowing is converted into a return current on a ground through-hole, and the return current is caused to flow through the ground through-hole. 2. An apparatus according to claim 1, wherein an insulator is disposed between the ground through-hole and the power supply layer, and the insulator has a function of a capacitance acting as a capacitance between the ground layer and the power supply layer. A multilayer printed wiring board characterized by making it easy to flow a high-frequency current. 3. A conductor is laminated on both sides of an insulator and plated on both sides of the conductor, and an insulator is filled therein to form a through hole for ground, and one conductor is used for ground. A step of manufacturing a double-sided conductive base material which is a ground layer connected to a through-hole and the other conductor is a power supply layer; A multilayer board manufacturing process of forming a multilayer board by laminating through prepregs on both sides of the material, forming a hole coaxially through a ground through hole of the multilayer board, plating this hole, and passing a signal through. Forming a hole and forming a signal wiring connected to the signal through-hole. A method for manufacturing a multilayer printed wiring board, comprising: 4. A method for manufacturing a multilayer printed wiring board according to claim 3, wherein the conductor layers formed in the double-sided conductor substrate manufacturing step are connected to a kisei capacitance by a clearance between the conductor layer and the ground through hole. .