JP4671333B2 - Multilayer printed circuit board and electronic equipment - Google Patents

Description

  The present invention relates to a multilayer printed circuit board used for electronic equipment, and more particularly to a high quality multilayer printed circuit board with reduced radiation noise and an electronic equipment using the same.

  With the recent miniaturization of electronic devices, the density of circuits formed on a printed circuit board mounted on the electronic devices has increased, and the operation has been accelerated. As a result, electromagnetic interference (EMI), in which electromagnetic waves emitted from the printed circuit board adversely affect the operation of surrounding electronic devices, is a problem.

  For example, as described in Patent Document 1, in an electronic apparatus having a printed circuit board on which an integrated circuit element such as an IC or LSI is mounted, a high-frequency current flowing along with a high-speed switching operation of the mounted integrated circuit element is high. It is well known that electromagnetic noise is generated.

  Electromagnetic noise generated by a printed circuit board may cause malfunctions in the electronic device including the printed circuit board or in other electronic devices unless appropriate measures are taken to reduce the electromagnetic noise.

  Among such electromagnetic noises, what occupies a large specific gravity is radiation caused by a high-frequency current flowing into a power supply line or a current flowing due to circuit parasitic capacitance or parasitic mutual inductance, which is said to be common mode noise.

  For these electromagnetic noises, the mechanism for their generation is complicated, so there has been no effective countermeasures at locations close to their sources. For this reason, conventionally, countermeasures have been taken against electromagnetic interference of this type by covering the entire electronic device with a metal object.

  In order to prevent radiation due to high-frequency power supply current and noise generation due to plane resonance between the ground layer and the power supply layer, a decoupling capacitor is often disposed in the vicinity of a circuit element such as an LSI that is the generation source.

  This is because the high frequency current flowing in the power supply layer in accordance with the switching operation of the IC / LSI mounted on the printed circuit board is bypassed to the ground layer through the decoupling capacitor in the vicinity of the IC / LSI and the switching of the IC / LSI is performed. This is to suppress the voltage fluctuation of the power supply terminal portion of the IC / LSI accompanying the operation.

  Furthermore, there is a problem of radiation noise generated at the resonance frequency of the LC circuit formed from the ground layer, the power supply layer, and the integrated circuit element mounted.

JP 2001-24334 A

  The problem to be solved is that the conventional technology cannot effectively cope with the radiation noise generated at the resonance frequency of the LC circuit formed from the ground layer, the power supply layer, and the integrated circuit element mounted thereon. It is.

  An object of the present invention is to solve these problems of the prior art and improve the quality of a multilayer printed circuit board.

In order to achieve the above object, a multilayer printed circuit board according to the present invention includes: (1) a plurality of circuit elements, and a ground layer, a signal layer, and a power supply layer for supplying a power supply voltage to the circuit elements, respectively; A multilayer printed circuit board laminated with a power source layer and a ground layer facing each other in a square of the same area with one side having a length equal to or less than ¼ wavelength of the maximum operating frequency of the circuit element in forming a uniformly divided areas obtained by equally dividing all the equally divided areas are patterned so as not to create and loop to increase the high frequency impedance is connected to the equally divided areas adjacent to said Rukoto . Or a (2) equally divided area adjacent to the equally divided areas, characterized in that a configuration of connecting with the electronic circuit components of the low-pass filter.

  According to the present invention, the power supply and the ground layer are equally divided to suppress the flow of the high-frequency power supply current that flows along with the high-speed switching operation of the integrated circuit element into other regions, and the ground layer and the power supply layer are mounted. By shifting the resonance frequency of the LC circuit formed from the integrated circuit element to a frequency higher than the target frequency of EMI regulation, radiation noise generated from the multilayer printed circuit board can be reduced. In addition, by dividing the square with a length of 1/4 wavelength or less of the maximum operating frequency of the circuit element into one side, the radiated noise generated by the high frequency power supply current that flows along with the high-speed switching operation of the integrated circuit element is resonant. Can be prevented, and radiation noise generated from the multilayer printed circuit board can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a cross-sectional configuration example of a multilayer printed circuit board according to the present invention, and FIG. 2 is a top view showing a first connection configuration example of equally divided regions in the multilayer printed circuit board according to the present invention. 3 and 3 are top views showing a second connection configuration example of equally divided regions in the multilayer printed circuit board according to the present invention.

  As shown in FIG. 1, the multilayer printed circuit board of this example has a configuration in which a ground layer, a signal layer, and a power supply layer for supplying a power supply voltage to circuit elements are laminated via an insulating material. .

  In the multilayer printed circuit board having such a configuration, integrated circuit elements such as ICs and LSIs are mounted, and these integrated circuit elements become sources of electromagnetic radiation noise. In this example, the configuration shown in FIGS. 2 and 3 is used to suppress radiation noise flowing out from the integrated circuit element mounted on the multilayer printed circuit board in the power supply layer.

  Electromagnetic noise radiation is generally divided into normal mode and common mode, and its radiant energy is expressed as a function of the square of frequency in the case of normal mode radiation, and is proportional to the frequency in the case of common mode node radiation. In any case, the higher the frequency, the higher the radiation level.

  In the multilayer printed circuit board of this example, the power supply layer and the ground layer (hereinafter, the power supply layer and the ground layer are collectively referred to as a plane) are divided, and the divided areas are connected so that high-frequency noise does not flow out. Contain high-frequency power supply current that causes noise.

  By suppressing the radiation noise level flowing into the plane in this way, it is possible to prevent the frequency power source current generated from the IC or LSI from flowing out of the substrate.

  For example, in the multilayer printed circuit board 8 shown in FIG. 2, the plane 4 (the power supply layer and the ground layer) is formed by equally divided regions obtained by equally dividing regions facing each other into the same shape and the same area. In plane 2, plane 4 is divided into nine equal areas.

  Since the divided planes 4 have the same power supply voltage, they need to be connected to each other. In this example, it is connected only at one place with the adjacent region. In this way, the connection is made only at one place so as not to create a loop that is a factor that generates noise, and high-frequency noise is cut at the one connection place.

  In FIG. 2, the power supply wiring pattern 1 is used for such connection. In particular, the power supply wiring pattern 1 is patterned so as to have a high frequency impedance. Therefore, the high frequency noise generated in one region (plane 4) does not flow to the other connected region (plane 4).

  Further, in the multilayer printed circuit board 8a shown in FIG. 3, the planes 4 are connected to each other through the VIA 2 using the low-pass filter 3 as an electronic circuit component. Since the low-pass filter 3 does not pass high-frequency noise, high-frequency noise generated in one region does not flow to the other connected region.

  Further, in the multilayer printed circuit board shown in FIGS. 2 and 3, the size of the area of the plane 4 to be divided is a quarter wavelength of the maximum operating frequency of the integrated circuit element such as an IC or LSI mounted. It is a square with a short length as one side.

  In this way, the size of the area of the plane 4 to be divided is divided into squares each having a length shorter than a quarter wavelength of the maximum operating frequency of an integrated circuit element such as an IC or LSI that is mounted. Thus, amplification of noise level due to resonance of the high-frequency current flowing into each region can be prevented, and the noise level can be suppressed for each region.

  As described above with reference to FIGS. 1 to 3, the multilayer printed circuit boards 8 and 8 a of this example are equipped with a plurality of circuit elements to supply a power supply voltage to the ground layer, the signal layer, and the circuit elements. The power supply layers are laminated with insulating materials interposed therebetween, and the region (plane 4) where the power supply layer and the ground layer face each other is equally divided into the same shape and the same area. And each equal divided area is connected to another equal divided area only at one location. And it is set as the structure connected by the power supply wiring pattern 1 patterned so that high frequency impedance may be raised between equal division | segmentation areas, or the structure connected by the low-pass filter 3. FIG. Further, the equally divided region (plane 4) is formed by being divided into squares each having a length equal to or shorter than a quarter wavelength of the maximum operating frequency of the circuit element.

  As described above, the power supply and ground layers are equally divided (plane 4), and the power supply wiring pattern 1 or the low-pass filter 3 patterned so as to increase the high-frequency impedance of each plane 4 is connected. Suppressing the flow of the high-frequency power supply current that flows along with the high-speed switching operation of the circuit element into the other region, and the resonance frequency of the LC circuit formed from the ground layer, the power supply layer, and the integrated circuit element to be mounted is subject to EMI regulations The frequency can be shifted to more than the frequency, and radiation noise generated from the multilayer printed circuit board can be reduced.

  Furthermore, by dividing the square with a length of 1/4 wavelength or less of the maximum operating frequency of the circuit element into one side, the radiation noise generated by the high-frequency power supply current that flows along with the high-speed switching operation of the integrated circuit element is resonant. Can be prevented, and radiation noise generated from the multilayer printed circuit board can be reduced.

  Further, by using such a multilayer printed circuit board, the performance of the electronic device can be improved.

  In addition, this invention is not limited to the example demonstrated using FIGS. 1-3, In the range which does not deviate from the summary, various changes are possible.

It is a sectional side view which shows the cross-sectional structural example of the multilayer printed circuit board concerning this invention. It is a top view which shows the 1st connection structural example of the equal division | segmentation area | region in the multilayer printed circuit board concerning this invention. It is a top view which shows the 2nd connection structural example of the equally divided area | region in the multilayer printed circuit board concerning this invention.

Explanation of symbols

  1: power supply wiring pattern, 2: VIA, 3: low-pass filter, 4: plane (equally divided into squares), 8, 8a: multilayer printed wiring board.

Claims (3)

A multilayer printed circuit board having a plurality of circuit elements mounted thereon, wherein a ground layer, a signal layer, and a power supply layer for supplying a power supply voltage to the circuit elements are laminated via insulating materials,
A region where the power supply layer and the ground layer are opposed to each other is formed as an equally divided region that is equally divided by a square of the same area with one side having a length equal to or less than ¼ wavelength of the maximum operating frequency of the circuit element. ,
All the equally divided areas are and patterned so as not to create a loop to increase the high frequency impedance is connected to the equally divided areas adjacent multilayer printed circuit board according to claim Rukoto. The multilayer printed circuit board according to claim 1,
A multilayer printed circuit board, wherein the equally divided region and the adjacent equally divided region are connected by an electronic circuit component of a low-pass filter. Electronic device characterized by using the multilayer printed circuit board according to claim 1 or claim 2.

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