JP2000307203A - Board for mounting electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the emission of radiation noise occurred by the leakage of the component of high frequency current overlapped with a power line to a board end part, by installing a power conductor layer connected to the power line as a conductor layer and a ground conductor layer connected to a ground line and forming them by means of making them face each other through an insulating layer. SOLUTION: In a multilayer printed board 11, the conductor layers 12a, 12b, 12c and 12d of four layers formed of the thin films of copper are stacked in a state where they are separated by the insulating layers 13a, 13b and 13c of three layers formed of thin films made of glass epoxy. The conductor layer 12b in the conductor layers 12b and 12c installed on an inner side is used as a power conductor layer connected to the power line and the conductor layer 12c is used as the ground conductor layer connected to a ground line. The conductor layers 12a and 12d exposed to a surface are used as signal conductor layers. Thus, the conductor layer 12b and the conductor layer 12c are formed in a confronted state through the insulating layer 13b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a power supply conductor layer connected to at least a power supply line as a conductor layer and a ground conductor layer connected to a ground line, which are opposed to each other via an insulating layer. The present invention relates to a formed electronic component mounting substrate.

[0002]

Heretofore, as this type of electronic component mounting board, there is a board in which, for example, a power supply line, a ground line, a signal line and the like are formed using a multilayer printed board. In this case, the power supply conductor layer connected to the power supply line and the ground conductor layer connected to the ground line are formed to face each other, thereby forming a capacitor between them and separately providing a capacitor as an electronic component. There is a technology that can be formed without using.

FIG. 6 shows a sectional structure of such a multilayer printed circuit board 1, in which three thin insulating layers 2a to 2c are provided.
And four conductive layers 3a provided with the layers interposed therebetween.
1 to 3d. The two inner conductive layers 3b and 3c are used as a power supply conductive layer connected to a power supply line and a ground conductive layer connected to a ground line, respectively. The conductive layers 3a and 3d exposed on the front and back are used as signal conductive layers connected to signal lines.

In order to mount various electronic circuit components on the multilayer printed circuit board 1 and form a desired circuit, four conductive layers 3a to 3d are formed in an appropriate pattern shape, and if necessary, A circuit is formed by conducting between the conductive layers. When a high-frequency circuit is formed on the substrate 1, a capacitor formed between the conductive layers 3b and 3c has a relatively large capacity, so that a configuration that does not require a capacitor separately connected between the two may be obtained. it can.

However, when the multilayer printed circuit board 1 having such a configuration is used, there are the following problems. That is, when a high-frequency circuit is constituted by mounted electronic components, a high-frequency current component may be superimposed on the power supply conductor layer 3b which is a power supply line. On the other hand, in the multilayer printed board 1 having such a configuration, as shown in the figure, since the conductive layers 3b and 3c are exposed at the outer peripheral end surface of the board 1, high-frequency current superimposed on the power supply line is exposed at this portion. Since they leak and flow, they are emitted as radiation noise (indicated by arrows in the figure). Therefore, in order to prevent such radiation noise from leaking outside, it is necessary to provide a configuration such as shielding the multilayer printed circuit board 1 outside.

The present invention has been made in view of the above circumstances, and an object of the present invention is to minimize the emission of radiated noise generated due to leakage of a component of a high-frequency current superimposed on a power supply line from an end of a substrate. It is an object of the present invention to provide an electronic component mounting substrate which does not require a separate shielding structure.

[0007]

According to the first aspect of the present invention, an electronic component mounting board such as a multi-layer printed circuit board is connected to at least a power supply conductor layer connected to a power supply line as a conductive layer and a ground line. And a ground conductor layer, which is formed in a state where they face each other with an insulating layer interposed therebetween. Since it is formed so as to be inwardly receded, when there is a high-frequency current flowing from the outer peripheral end of the power supply conductor layer to the outer peripheral end of the ground conductor layer, it does not largely flow out of the substrate. This makes it possible to minimize the generation of radiation noise.

According to the second aspect of the present invention, the power supply conductor layer is
The recessed dimension with respect to the ground conductor layer is set to a dimension that reduces radiation noise generated due to a high-frequency signal superimposed on the power supply line to a predetermined level or less, that is, is set in consideration of a required amount of radiation noise suppression. Therefore, the generation of radiation noise leaking out of the substrate can be suppressed, and the function as a necessary capacitor can be realized in the area where the power supply conductor layer and the ground conductor layer face each other.

According to the third aspect of the present invention, a guard conductor layer is formed at a peripheral portion of the power supply conductor layer so as to surround it at a predetermined interval, and the guard conductor layer is electrically connected to the ground conductor layer. Therefore, the leakage of the high-frequency current component flowing between the power supply conductor layer and the ground conductor layer to the outside can be further reduced, whereby the generation of radiation noise can be reduced as much as possible.

According to the fourth aspect of the invention, since the signal conductor layer connected to the signal line via at least one of the power supply conductor layer and the ground conductor layer and the insulating layer is provided, the power supply conductor layer and the ground conductor are provided. Forming a circuit configuration using a multilayer wiring pattern with the signal conductor layer connected to the signal line while suppressing the generation of radiation noise between the layers and increasing the capacitance component of the formed capacitor Will be able to

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a configuration of a multilayer printed circuit board 11 according to the present invention, in which four conductor layers 12a, 12b, 12c, and 12d made of a copper thin film are replaced with three insulating layers made of a glass epoxy thin film. 13a, 13B, 13d
Are stacked in a separated state. Here, each of the conductor layers 12a to 12d has a thickness of 0.2 mm.
The insulating layers 13a to 13
The thickness of c is adjusted.

The conductor layers 12a and 12d disposed on the front side and the back side, respectively, are connected to signal lines and are formed as signal conductor layers. Of the conductor layers 12b and 12c disposed on the inner side, the conductor layer 12b is used as a power conductor layer connected to a power line, and the conductor layer 12c is used as a ground conductor layer connected to a ground line. . The conductor layers 12a and 12d exposed on the surface are used as signal conductor layers, respectively.

Since the conductor layer 12b and the conductor layer 12c are formed so as to be opposed to each other with the insulating layer 13b interposed therebetween, this becomes a capacitor, and a large-capacity capacitor is provided between the power supply line and the ground line. The configuration is such that a capacitor is connected. As a result, the power supply impedance in the circuit configuration can be reduced to reduce high frequency noise superimposed on the power supply line, and such a function can be achieved without separately providing a capacitor.

The conductor layer 12b, which is a power supply conductor layer, is formed to a position retracted by a predetermined retreat dimension d from the outer peripheral edge, and the other conductor layers 12a, 12c, 12d are formed to the outer peripheral edge. . This is because, as described later, when the conductor layer 12b is connected to a power supply line to form a circuit,
This is because even if a high-frequency signal is superimposed on the conductor layer 12b, the high-frequency signal is prevented from radiating as radiation noise at the outer peripheral portion of the portion facing the conductor layer 12c as the ground conductor layer.

The dimension d for retracting the conductor layer 12b
Is a dimension required to suppress the generation of radiation noise at the frequency of the high-frequency signal handled by the high-frequency circuit used, as described in the experimental results described later. The value of the dimension d is determined by the frequency of the circuit to be mounted, the conductor layers 12b, 1
In accordance with various conditions such as the facing area 2c, the material (relative permittivity) of the insulating layer 13b, and the plate thickness, the value is set to a value derived in an appropriate relationship based on the experimental results. Further, in this embodiment, the retreat is made equally from the outer peripheral edge by the retreat dimension d. However, an appropriate dimension can be set as long as it is equal to or more than the necessary retreat dimension d.

In the multilayer printed circuit board 11 having the above structure, for example, when an electronic circuit component is mounted on the front side or the back side to form a high frequency circuit, the power supply conductor layer 12b
By forming a large-capacity capacitor between the capacitor and the ground conductor layer 12c, the power supply impedance can be reduced.

In this case, the power supply conductor layer 12b forming the capacitor extends from the outer peripheral edge of the substrate 11 to a position inside by a predetermined retreat dimension d.
As shown in the figure, the amount S of the high-frequency current component flowing between the ground conductor layer 12c and the power conductor layer 12b to the outside is suppressed, and the high-frequency current component is located almost inside the outer peripheral edge where the ground conductor layer 12c terminates. Become. As a result, the substrate 1
1 reduces the high-frequency current component passing through the outside, thereby minimizing the generation of radiation noise.

Next, data for demonstrating the principle of the above-described embodiment will be described with reference to FIGS. 2 to 4 based on experimental results conducted by the inventor. FIG.
The printed circuit board 14 used in the experiment is shown. In this experiment, the printed circuit board 14 is based on an insulating layer (made of glass epoxy) 15 having a thickness t of about 1 mm. The conductor layers 16a and 16b are formed on each surface. The external dimensions of the printed circuit board 14 are, for example, a vertical dimension A = 96 mm and a horizontal dimension B = 160 mm.
It is. The conductor layer 16a as the power supply conductor layer is formed up to a position recessed by a retreat dimension d (mm) from the outer dimension of the printed board 14, and the outer dimension is a vertical dimension a = 96−2 × d (mm). ), Lateral dimension b = 160-2 × d
(Mm).

In the internal region of the power supply conductor layer 16a,
In order to dispose the experimental circuit 17, the conductor layer 1 is formed in a rectangular shape (for example, a vertical dimension C1 = 20 mm and a horizontal dimension C2 = 80 mm).
6a is removed to provide a circuit formation region. In this circuit formation region, as a test electronic circuit component, a quartz oscillator 18, an inverter circuit 19, capacitors 20a and 20b, a resistor 21, and wiring portions 22a and 2 are provided.
An experimental circuit 17 using 2b is provided.

This is a simple oscillation circuit formed between a power supply conductor layer 16a connected to a power supply line and a ground conductor layer 16b connected to a ground line, as shown in FIG. Vibrator (oscillation frequency 20MHz)
Numeral 18 is supplied with power from a power supply line (power supply voltage 5 V), and its vibration output is output from a wiring section 22a and an inverter circuit (ASO4).
19, the wiring section 22b is terminated to the ground line via a resistor (resistance value 50Ω) 21. The terminals connected to the power supply lines of the crystal unit 18 and the inverter circuit 19 are connected to ground lines via capacitors (0.1 μF) 20a and 20b, respectively.

With the above arrangement, the capacitors 20a, 20b
When the high-frequency current of the crystal unit 18 is superimposed on the power supply line without being absorbed by the power supply line, when the high-frequency current flows between the power supply conductor layer 16a and the ground conductor layer 16b as a high-frequency current, it is emitted to the outside as radiation noise. Will be. The inventor measured the degree of emission as the radiation noise using the aforementioned receding dimension d as a parameter. The measurement of the radiation noise level is performed in a small anechoic chamber.

FIG. 4 shows the measurement results of the radiation noise generation level (dB · μV / m) under the above-mentioned conditions, and the results when the receding dimension d from the outer peripheral edge of the power supply conductor layer 16a is plotted on the horizontal axis. As shown. The measured retraction dimension d is 0
mm, 20 mm, 30 mm, and 35 mm, and in each measurement, the measurement frequency was increased from 30 MHz to 1
The noise level was measured by sweeping to the range of 000 MHz, and the frequency (160 M
Hz, 180 MHz, 240 MHz, 260 MHz, 2
80MHz, 300MHz, 320MHz, 360MH
The noise level difference in z) is observed for each receding dimension d.

From these results, it can be seen that under this condition, regardless of the oscillation frequency, the retreat dimension d is significantly improved when the retraction dimension d is set to 30 mm or more as compared with the case where the retraction dimension d is up to 20 mm. It can be seen from the above that the improvement effect can be relatively increased by taking the receding dimension d of about 25 mm or more.

In the above configuration, the capacitance of the capacitor formed by the power supply conductor layer 16a and the ground conductor layer 16b is as follows. That is, the receding dimension d
The capacitance C (d) of the capacitor obtained as a function of
Since it is determined from the electrode area, the facing distance, and the relative permittivity εr of the insulating layer 15, the following equation (1) is obtained. Here, since the area S of the power supply conductor layer 16a is expressed by the equation (2),
Assuming that the vacuum dielectric constant is εo, C (d) = εr × εo × S / d (1) S = a × b−C1 × C2 (2) = (A−2 × d) × (B− 2 × d) −C1 × C2.

Considering the case where the receding dimension d is 0 mm, when the insulating layer 15 is made of glass epoxy, its relative dielectric constant εr is 4.6.
(0) is C (0) = 4.6 × 4π × 10 ⁻⁷ × 0.01376 / (1 × 10 ⁻³ ) = 79.54 (μF) (3) From now on, the capacitor 2 used in the experimental circuit 17 will be described.
Since 0a and 20b are about 0.1 μF as described above, they are extremely smaller than the capacitance C (d) of the capacitor formed by the power supply conductor layer 16a and the ground conductor layer 16b. Is a property that can be omitted. As the receding dimension d increases, the capacitance C of the capacitor changes to a value smaller than the capacitance value (79.54 μF) obtained by the equation (3). The value is large.

Therefore, by setting the value of the receding dimension d to be about 25 mm or more, the generation level of the radiated noise is reduced by about 10 dBμV / m while the capacity of the capacitor C is sufficiently secured to reduce the power supply impedance. It could be configured. Based on this, the retreat dimension d of the multilayer printed board 11 in the above-described embodiment is
The same effect can be obtained by setting.

According to the present embodiment, the multilayer printed circuit board 11 is divided into the conductor layers 12 b and 12 c and the insulating layer 1.
3b, the conductor layer 12b is formed in a shape extending from the outer peripheral edge to a position recessed by the receding dimension d while providing a capacitor for reducing the power source impedance. Therefore, when an electronic circuit component is mounted on the multilayer printed circuit board 11 to form a high-frequency circuit, it is not necessary to separately provide a configuration for shielding radiation noise outside.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
In the following, portions different from the first embodiment will be described. That is, in the multilayer printed board 23 of this embodiment, in addition to the configuration of the first embodiment, a guard conductor layer 24 is provided on the outer periphery of the power supply conductor layer 12b so as to surround it, and the ground conductor layer is formed on the outer periphery. 12c.

In the same manner as described above, the power supply conductor layer 12b is formed from the outer peripheral edge of the substrate 23 to a position retracted by the receding dimension d, and the guard conductor layer 24 provided on the outer periphery thereof is larger than the receding dimension d. They are arranged so as to face each other with a small gap g therebetween.

With this configuration, even if the component of the high-frequency current superimposed on the power supply line described in the first embodiment spreads outside the power supply conductor layer 12b, the component of the high-frequency current is Since the guard conductor layer 24 located in the portion is electrically connected to the ground conductor layer 12c, it is possible to adopt a configuration in which the generation of radiation noise is suppressed as much as possible.

In the above configuration, the guard conductor layer 24 is connected to the ground conductor layer 12c at the outer peripheral edge of the substrate 23, but penetrates the conductor into the insulating layer 12a inside the outer peripheral edge. It is good also as a structure which arrange | positions and conducts electricity like this. The conductor layer 24 is formed on the substrate 23.
Is formed up to the outer peripheral edge portion, but it may be configured as an annular conductor layer having a predetermined width to conduct with the ground conductor layer 12c.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. In each of the above embodiments, the case of the multilayer printed circuit boards 11 and 23 having the configuration in which the four conductor layers 12a to 12d are provided has been described. In such a case, another conductor layer may not be provided, or one or more layers may be provided. Although the case where the insulating layer of the substrate is made of glass epoxy has been described, the present invention can also be applied to a substrate on which an insulating layer using ceramic or the like is formed.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagram corresponding to FIG. 1 of a printed circuit board used in an experiment.

FIG. 3 is an electrical configuration diagram of an experimental circuit.

FIG. 4 is a diagram showing a measurement result of a radiation noise level with respect to a receding dimension;

FIG. 5 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;

FIG. 6 is a sectional view of a substrate showing a conventional example.

[Explanation of symbols]

11 is a multilayer printed board (electronic component mounting board), 12
a and 12d are signal conductor layers, 12b is a power supply conductor layer, 12c
Is a ground conductor layer, 13a to 13c are insulating layers, 14 is a printed board (electronic component mounting board), 15 is an insulating layer, 16
a is a power supply conductor layer, 16b is a ground conductor layer, 17 is an experimental circuit, 18 is a crystal oscillator, 19 is an inverter circuit, 20
a and 20b are capacitors, 21 is a resistor, 23 is a multilayer printed circuit board (electronic component mounting board), and 24 is a guard conductive layer.

Claims (4)

[Claims] An electronic component comprising at least a power supply conductor layer connected to a power supply line as a conductor layer and a ground conductor layer connected to a ground line, and these are arranged and formed facing each other with an insulating layer interposed therebetween. In the mounting board, the power supply conductor layer is formed so that an outer peripheral edge thereof is located at a position recessed inward by a predetermined retreat dimension with respect to a region where the ground conductor layer is formed. Substrate for mounting electronic components. 2. The electronic component mounting board according to claim 1, wherein the power supply conductor layer has a recessed dimension with respect to the ground conductor layer, and radiation noise generated due to a high-frequency signal superimposed on the power supply line. Is set to a dimension not more than a predetermined level. 3. The electronic component mounting board according to claim 1, wherein the substrate is provided so as to surround the outer periphery of the power supply conductor layer at a predetermined interval and is electrically connected to the ground conductor layer. An electronic component mounting substrate, comprising a guard conductor layer provided thereon. 4. The electronic component mounting board according to claim 1, wherein a signal conductor layer connected to a signal line via at least one of the power supply conductor layer and the ground conductor layer and an insulating layer. An electronic component mounting board characterized by being formed.