JP3782577B2 - Multilayer printed wiring board and electronic apparatus provided with the wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer printed wiring board and an electronic device provided with the wiring board, and in particular, a multilayer devised as a conductive layer constituting the printed wiring board and a method for connecting the conductive layers in order to suppress radiation noise from the electronic device. The present invention relates to a printed wiring board and an electronic device including the wiring board.
[0002]
[Prior art]
FIG. 9 is a schematic perspective view showing a connection structure between housings in a conventional electronic apparatus. In general, a ground (hereinafter referred to as GND) pattern provided on a printed wiring board is desired to be designed so as to reduce potential fluctuation. This is to suppress the generation of unnecessary current accompanying the potential fluctuation of the GND pattern on the wiring board.
[0003]
As a conventional method of this GND design, there is a method of increasing the area of a conductor pattern serving as GND, or providing a GND layer with a wiring board having a multilayer structure. These reduce the inductance component of the GND pattern and suppress the current and electromagnetic waves generated with respect to potential fluctuations.
[0004]
In addition, there is a method of suppressing potential fluctuation of the printed wiring board by connecting the GND of the printed wiring board and a conductive member of a casing, which often has less potential fluctuation, with low impedance.
[0005]
However, when a printed wiring board has a multilayer structure and a GND layer is provided, or when GND on the printed wiring board is connected to a conductive member of a housing, a standing wave is generated at a certain frequency at a current flowing on the wiring board. Thus, there may be a problem of radiation noise. This frequency is mainly determined by the harmonic frequency of the digital clock signal, the size of the wiring board, the dielectric constant of the dielectric material constituting the wiring board, and the like.
[0006]
Furthermore, since the connection location is generally low impedance by connecting with the conductive member of the housing, current may easily flow through the connection location. Occurs, causing radiation noise.
[0007]
As a conventional method for suppressing the radiation noise caused by the standing wave, there are a method of connecting at a plurality of locations and a method of giving resistance to the connecting portion mentioned in JP-A-7-225634.
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned conventional example, when the structure of the casing constituting the device is such that two printed wiring boards 18 and 18 'as shown in FIG. Thus, there may not be a conductive member of the housing that faces the wiring board in the vicinity, and even if there is a conductive member that faces the board, it is not sufficiently large and shaped compared to the printed wiring board There is.
[0009]
In particular, from the viewpoint of production cost and recycling, it is becoming less likely that the electronic device casing is made of metal, and it is difficult to work as GND sufficient for countermeasures against electromagnetic noise.
[0010]
In addition, the GND pattern or GND layer provided on the printed wiring board can be designed by dividing the GND conductor pattern for each application, for example, for analog signals, digital signals, and GND for connection to the housing. Often there is. In addition, the conductor pattern of the power supply provided on the printed wiring board may be divided according to the drive voltage of the circuit, and in the GND design of the printed wiring board, ensure a sufficient conductor pattern to suppress unnecessary current. May be difficult.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer printed wiring board and an electronic device equipped with this wiring board that have a structure that stabilizes the potential of the GND pattern of the printed wiring board and suppresses radiation noise caused by a standing wave or the like. Is to provide.
[0012]
[Means for Solving the Problems]
To achieve the above object, the present invention, a first conductive layer conductor pattern and the conductive pattern for grounding of the signal are mixed, is disposed via the first conductive layer insulating layer, A multilayer printed wiring board having a second conductive layer made of a conductor having a plane area equivalent to that of the first conductive layer, wherein the ground conductive pattern of the first conductive layer is formed on the multilayer printed wiring board. It is electrically connected to the second conductive layer through a connection portion having an impedance value corresponding to the generated standing wave . In this case , a hole for inserting a connector or a lead type electronic component into the printed wiring board may be provided in the second conductive layer, but other conductive patterns of the second conductive layer and the signal-GND mixed layer. In addition, a low impedance connection is not made through means such as through holes or soldering.
[0013]
With the above-described configuration, the second conductive layer can function as GND by capacitive coupling with respect to a digital logic signal in a high frequency region of, for example, several tens of MHz or more, and stabilizes potential fluctuation. Moreover, the radiation noise caused by the standing wave can be suppressed by the impedance at the connection point.
[0014]
Furthermore, since unnecessary current and unnecessary electromagnetic waves generated from the printed wiring board can be suppressed, the configuration is hardly affected by the conductive member of the housing.
[0015]
Further, the multilayer printed wiring board of the present invention may be made by a built-up method, in which case the base layer of the build-up is the second conductive layer, and the signal-GND mixed layer is laminated with the built-up layer. By doing so, it is possible to build without increasing the connection between the buildup layer and the base layer.
[0016]
In addition, as a method of giving impedance to the connection part, electronic parts may be connected by soldering or screwing, or may have electric characteristics depending on the shape of the conductor pattern, or magnetic properties such as ferrite. You may use your body. Furthermore, the impedance of the connection portion may be changed with respect to the frequency change by combining a plurality of these.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a schematic cross-sectional view of an embodiment of a printed wiring board according to the present invention, and FIG. 2 is a schematic top view of each conductive layer of the embodiment. FIG. 1 is a first embodiment of the present invention and conceptually shows a layer structure of a multilayer printed wiring board mounted on an electronic device. In FIG. 1, in the first conductive layer 1, a conductor pattern 2 for digital signals and a conductor pattern 3 for GND are mixed, and one second conductive layer 4 is equivalent to a printed wiring board. It consists of a conductor having a flat area, and an insulator for insulation is interposed between the conductive layers. The second conductive layer 4 is connected to the GND conductor pattern 3 of the first conductive layer 1 by an electric element 5 having impedance, and other than the GND conductor pattern 3 of the first conductive layer 1. The conductor pattern, for example, the digital signal conductor pattern 2 and the second conductive layer 4 are not electrically connected via soldering or electric elements.
[0019]
In the schematic top view of each conductive layer in FIG. 2, it is assumed that an insulator is interposed between the conductive layers. In FIG. 2, the first conductive layer group 1 ′ is composed of two first conductive layers 1 a and 1 b, and the GND conductive pattern 3 of each conductive layer 1 a and 1 b is electrically connected through the through hole 6. is there. A through hole 6 ′ for electrically connecting each other is provided at one end of each of the GND conductor pattern 3 and the second conductive layer 4, and the GND conductor of the first conductive layer group 1 ′ is provided. In the pattern 3, a mounting land on which a chip type electronic component can be mounted is provided immediately before the connection with the through hole 6 '. For example, the chip type inductor component 7 is mounted and connected by soldering.
[0020]
The solder connection in this example may be an electrical connection by a method such as a conductive adhesive. Moreover, the location where the GND pattern of the first conductive layer group and the second conductive layer are connected may be an arbitrary location on the printed wiring board, and may be plural. Furthermore, the impedance of each connection location in the case of multiple connections may be different.
[0021]
Here, the chip-type inductor component is used in this embodiment, but a lead-type electronic component may be used by providing a through-hole land.
[0022]
In addition to the first conductive layer and the second conductive layer, there may be a conductive layer for supplying drive power, and for supplying drive power to the first conductive layer and the second conductive layer. There may be a conductor pattern. Further, the second conductive layer may have a gap for mounting a lead-type electronic component or a connector.
[0023]
Next, a second embodiment will be described.
[0024]
FIG. 3 is a schematic top view of a part of the conductive layer of the second embodiment. The present embodiment is an example in which a part of the first embodiment is modified. In FIG. 3, the conductive layer 1a includes a conductor pattern 2 for digital signals (not shown) and a conductor pattern 3 for GND, and the second conductive layer 4 is a conductor having a plane area equivalent to that of a printed wiring board. Represents. A through hole 6 ′ for electrical connection with the second conductive layer 4 is provided in a part on the conductive layer 1a. Between the through hole 6 ′ and the GND conductor pattern 3, A surface-mount land on which the chip-type resistor component 8 and the chip-type capacitor component 9 can be mounted in parallel is provided, and the general through holes 6 and the GND conductor pattern 3 are connected by soldering (not shown). .
[0025]
With the configuration described above, the GND conductive pattern 3 of the first conductive layer and the second conductive layer 4 can be connected via a resistive and capacitive impedance.
[0026]
Here, in this embodiment, the chip-type resistor component 8 and the chip-type capacitor component 9 are connected via impedance, but an inductor component or the like may be used. It may be a composite part by any combination of resistance, inductance, and capacitance.
[0027]
Next, a third embodiment will be described.
[0028]
FIG. 4 is a schematic top view of a part of the conductive layer of one example of the third embodiment, and FIG. 5 is a schematic top view of each conductive layer of the second example of this embodiment. .
[0029]
The third embodiment is a modified example of the second embodiment. 4 and 5, the conductive layer 1a is a mixture of a conductor pattern 2 for digital signals and a conductor pattern 3 for GND, and the second conductive layer 4 has a plane area equivalent to that of a printed wiring board. It represents a conductor with A through hole 6 ′ for electrical connection with the second conductive layer 4 is provided in a part on the conductive layer 1a. Between the through hole 6 ′ and the GND conductor pattern 3, By configuring the conductor pattern to be folded, the folded pattern inductor 10 having inductance and the chip-type capacitor component 9 are arranged in series and are electrically connected by soldering (not shown).
[0030]
By adopting the above-described configuration, the GND conductor pattern 3 provided on the first conductive layer 1a and the second conductive layer 4 are connected with an impedance that can be expressed by an inductance and capacitive series circuit. Can do.
[0031]
In this embodiment, the folded pattern inductor 10 having inductance is used. However, as a second embodiment, a spiral pattern inductor 11 as shown in FIG. 5 may be used.
[0032]
Next, a fourth embodiment will be described.
[0033]
FIG. 6 is a schematic top view of a part of the conductive layer of the fourth embodiment.
[0034]
The present embodiment is a modified example of the third embodiment. In FIG. 6, the conductive layer 1a contains a conductor pattern 2 (not shown) for digital signals and a conductor pattern 3 for GND, and the second conductive layer 4 has a plane area equivalent to that of a printed wiring board. It is a conductor with A through hole 6 ′ for electrical connection with the second conductive layer 3 is provided in a part on the conductive layer 1a. Between the through hole 6 ′ and the GND conductor pattern 3, By forming the conductor pattern in a comb shape, the conductor patterns are electrically connected by a comb-shaped pattern capacitor 12 having capacitance.
[0035]
With the above-described configuration, the GND pattern provided in the first conductive layer and the second conductive layer can be capacitively connected.
[0036]
Next, a fifth embodiment will be described.
[0037]
FIG. 7 is a schematic perspective view showing the configuration of each conductive layer of the fifth embodiment.
[0038]
In FIG. 7, the first conductive layer group 1 ′ is composed of conductive layers 1a and 1b in which conductor patterns for digital signals and GND are mixed, and a dielectric layer 13 provided between the conductive layers 1a and 1b. Become. One second conductive layer 4 is made of a conductor having a plane area equivalent to that of a printed wiring board, and a dielectric material and a magnetic material are interposed between the first conductive layer group 1 ′ and the second conductive layer 4. There is a mixed layer 14. The second conductive layer 4 is connected to the GND pattern of the first conductive layer group 1 ′ by an electric element 5 having impedance, and a conductor pattern other than the GND pattern 3 of the first conductive layer. For example, the conductor pattern 2 for digital signal and the second conductive layer 4 are not electrically connected via soldering or electric elements.
[0039]
With the configuration described above, unnecessary current flowing through the GND conductor pattern 3 of the first conductive layer can be absorbed by the magnetic material between the second conductive layer 4 and unnecessary. Electromagnetic waves can be suppressed.
[0040]
Next, a sixth embodiment will be described.
[0041]
FIG. 8 is a schematic cross-sectional view of the sixth embodiment. FIG. 8 conceptually shows the layer structure of the printed wiring board of the sixth embodiment. The printed wiring board of this embodiment is made by a build-up method. In FIG. 8, the first conductive layer 15 is laminated by the build-up method, and the digital signal conductor pattern 2 and the GND conductor are formed. The pattern 3 is mixed, and the second conductive layer 16 is a printed circuit board having a plane area equivalent to that of the printed wiring board and made by press molding. Then, the GND conductor pattern 3 of the first conductive layer 15 and the second conductive layer 16 are connected via an electric element 5 having impedance, and the GND conductor pattern 3 of the first conductive layer 15 is connected. Other conductor patterns, for example, the digital signal pattern 2 and the second conductive layer 16 are not electrically connected via soldering or electrical elements.
[0042]
With the above-described configuration, wiring for digital signals and the like is formed in the build-up layer, so that high-density wiring is possible and unnecessary radiation noise can be suppressed.
[0043]
【The invention's effect】
The invention as described above, the insulating respect conductive layer constituting the multilayer print circuit board, a first conductive layer conductor pattern and the conductive pattern for grounding of the signal mixed, with the first conductive layer And a second conductive layer made of a conductor having a plane area equivalent to that of the first conductive layer, and a conductive pattern other than the GND conductive pattern of the first conductive layer and the second conductive layer. The second conductive layer is not electrically connected to the second conductive layer, and the GND conductive pattern of the first conductive layer and the second conductive layer have impedance values corresponding to standing waves generated in the multilayer printed wiring board. A multilayer printed wiring board having a structure in which the GND potential of the printed wiring board is stable and suppresses radiation noise caused by standing waves and the like. Provide electronic equipment with Effect that can be there.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an embodiment of a printed wiring board according to the present invention.
FIG. 2 is a schematic top view of each conductive layer of the present embodiment example.
FIG. 3 is a schematic top view of a part of a conductive layer according to a second embodiment.
FIG. 4 is a schematic top view of a part of a conductive layer according to an example of the third embodiment;
FIG. 5 is a schematic top view of each conductive layer of a second example of the third embodiment.
FIG. 6 is a schematic top view of a part of a conductive layer according to a fourth embodiment.
FIG. 7 is a schematic perspective view showing the configuration of each conductive layer in a fifth embodiment.
FIG. 8 is a schematic cross-sectional view of a sixth embodiment example.
FIG. 9 is a schematic perspective view showing a connection structure between casings in a conventional electronic apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 1a, 1b 1st conductive layer 1 '1st conductive layer group 2 Conductor pattern 3 for digital signals 3 Conductor pattern 4 for GND 2nd conductive layer 5 Electric element 6, 6' which has impedance Through-hole 7 Chip Inductor Component 8 Chip Resistor Component 9 Chip Capacitor Component 10 Folded Pattern Inductor 11 Spiral Pattern Inductor 12 Comb Shape Pattern Capacitor 13 Dielectric Layer 14 Dielectric and Magnetic Mixed Layer 15 By Build-up Method Laminated first conductive layer 16 Second conductive layer 17 as base layer of build-up method Conductive members 18 and 18 'of electronic device casing Printed wiring board 19 Connection between printed wiring board and electronic device casing

Claims (9)

A first conductive layer in which a signal conductor pattern and a ground conductor pattern are mixed, and a conductor that is disposed via the first conductive layer and an insulating layer and has a plane area equivalent to that of the first conductive layer In a multilayer printed wiring board having a second conductive layer comprising :
Conductor patterns for ground of the first conductive layer is electrically connected to the second conductive layer via a connecting portion having an impedance value corresponding to the standing wave generated in the multilayer printed circuit board A multilayer printed wiring board characterized by that. Before Kise' connection portion is resistive, capacitive, multi-layer printed wiring board according to claim 1, characterized in that at least two inductive a circuitry element group formed in combination. The multilayer printed wiring board according to claim 2 , wherein the circuit element group is configured such that resistance and capacitance are in series. The connecting portion, the multilayer printed wiring board according to claim 1, characterized in that the conductor pattern formed on in fold returns shape.   The multilayer printed wiring board according to claim 1, wherein the connection portion is a conductor pattern formed in a spiral shape.   The multilayer printed wiring board according to claim 1, wherein the connection portion is a conductor pattern formed in a comb shape.   The multilayer printed wiring board according to claim 1, wherein the insulating layer is a mixed layer of a dielectric and a magnetic material.   2. The multilayer printed wiring board according to claim 1, wherein the first conductive layer is formed by a build-up method using the second conductive layer as a base layer. 3.   The electronic device provided with the multilayer printed wiring board of any one of Claim 1 thru | or 8.

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