JP2003204166A - Multilayer printed circuit board - Google Patents

Abstract

(57) Abstract: Provided is a multilayer printed circuit board which is limited to radiated electromagnetic noise in an FM broadcast frequency band and has optimized constants of an inductance element and a capacitor element. SOLUTION: A power supply pattern surface S near an IC near the IC.
Capacitor 110 between the ground pattern surface G
In addition, in the multilayer printed circuit board in which the shape of the power supply pattern surface near the IC is elongated, the frequency at which the highest frequency among the harmonics of the IC included in the FM broadcast frequency band is highest and the FM broadcast frequency band Between the maximum frequency and the resonance frequency (f = 1 / (2π√ (L1 · C1)) calculated by the inductance component L1 and the capacitance component C1 included in the bypass capacitor. Configured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of decoupling an IC mounted on a printed circuit board for reducing electromagnetic radiation noise, and more particularly to a ground pattern surface for suppressing noise in a printed circuit board used in electronic equipment. The present invention relates to a multilayer printed circuit board using a bypass capacitor inserted between power supply pattern surfaces.

[0002]

2. Description of the Related Art A conventional multilayer printed circuit board disclosed in, for example, Japanese Patent Laid-Open No. 10-223997 discloses an IC
In order to suppress the harmonic noise conducted to the ground pattern and the power supply pattern from, the low-pass filter composed of the inductance element by the pattern and the capacitor element by the electronic circuit component is arranged.

[0003]

In such a multilayer printed circuit board, trial and error are necessary to determine the constants of the inductance element and the capacitor element, and the effect may not be sufficient. In the case of automobile electrical components, FM broadcast frequency band (76 MHz to 110 MHz,
It is important to suppress radiated electromagnetic noise in the following (FM band).

It is an object of the present invention to provide a multilayer printed circuit board which limits radiation electromagnetic noise in the FM band and optimizes the constants of the inductance element and the capacitor element.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned object, according to the present invention, a bypass capacitor is inserted between an IC near a power source pattern surface and a ground pattern surface, and the shape of the above power source pattern surface near the IC is further improved. In a multilayer printed circuit board having a slender shape, the inductance included in the bypass capacitor between the highest frequency of the harmonics of the IC included in the FM broadcast frequency band and the maximum frequency of the FM broadcast frequency band. The resonance frequency calculated by the component L1 and the capacitance component C1 (f = 1
A multilayer printed circuit board is characterized in that the bypass capacitor is configured such that / (2π√ (L1 · C1)).

Further, the inductance component L2 of the power supply pattern surface is larger than the inductance component L1 included in the bypass capacitor.

Further, in a multilayer printed board in which a bypass capacitor is inserted between the power supply pattern surface and the ground pattern surface near the IC in the vicinity of the IC, and the shape of the power supply pattern surface near the IC is elongated, the bypass capacitor is used as the bypass capacitor. The resonance frequency (f calculated by the included inductance component L1 and capacitance component C1 and the inductance component L2 of the elongated power source pattern surface
= 1 / (2π√ ((L1 + L2) C1))) is equal to or lower than the minimum frequency of the FM broadcasting frequency band, and the bypass capacitor and the elongated power source pattern surface are configured. It is in.

An IC included in the frequency band for FM broadcasting
There are two higher harmonics, and two bypass capacitors are inserted between the power supply pattern surface near the IC and the ground pattern surface near the IC, and the power supply pattern surface near the IC is elongated. In, the first bypass capacitor having the inductance component L1 and the capacitance component C1 is connected to the inductance component L3.
And a second bypass capacitor having a capacitance component C2, inserted closer to the IC, between the higher harmonic frequency of the IC harmonics and the maximum frequency of the FM broadcast frequency band, Resonance frequency (f = 1 / (2
π√ (L1 · C1))) and the frequency of the lower harmonic of the IC harmonics is the resonance frequency (f
= 1 / 2π√ ((L3 + L4) (C2)) (where L4 is the inductance component of the power supply pattern surface between the two bypass capacitors) and the resonance frequency (f = 1 / 2π√ ((L1 + L3 + L
4) (C1 · C2 / (C1 + C2))) and the resonance frequency (f = 1 / (2π√ ((L3 + L5) (C2)) (where L5 is the power supply on the power supply side of the two bypass capacitors). In the multilayer printed circuit board, the first and second bypass capacitors and the elongated power source pattern surface are configured such that the inductance component of the pattern surface) is equal to or lower than the minimum frequency of the FM broadcast frequency band. .

Further, the inductance component L4 between the first and second bypass capacitors on the power supply pattern surface is smaller than the inductance component L5 on the power supply side of the two bypass capacitors.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a diagram for explaining the structure of a multilayer printed circuit board according to Embodiment 1 of the present invention. In FIG. 1, the IC 100 is mounted on a multilayer printed circuit board having a power supply pattern surface S and a ground pattern surface G, each of which includes a metal elongated line pattern formed on the front surface and the back surface of the board and a wide plate-shaped pattern. And bypass capacitor 110 to IC100
One is installed in the vicinity. Bypass capacitor 1
10 is inserted between the power supply pattern surface S and the ground pattern surface G. The capacitance component of the bypass capacitor 110 is indicated by C1 and the inductance component is indicated by L1. The power supply pattern surface S has an elongated shape so as to have the inductance component L2.

First, of the harmonics of the driving frequency of the IC 100, the frequency f included in the FM band (76 to 110 MHz)
Calculate a. In this embodiment, the FM band (76-1
The case where the frequency included in 10 MHz) is one will be described.

Next, fa ≦ fx <110 MHz, fy <7
L having resonance frequencies fx and fy that satisfy 6 MHz
1, C1 and L2 are determined as shown in the following equations (1), (2) and (3). When resonating on the path a, the resonance frequency of the multilayer printed circuit board viewed from the IC 100 side becomes minimum,
Radiated electromagnetic noise is the smallest. When resonating on the path b, the resonance frequency of the multilayer printed board viewed from the IC 100 side becomes maximum, and the radiated electromagnetic noise becomes maximum.

This means that if the impedance when resonating in the transmission path a shown in FIG. 1 is determined only by the bypass capacitor 110, L1 and C1 having a resonance frequency fx satisfying fx = fa should be selected. But IC10
Since there is a lead inductance etc. in the 0 part, the IC10
Since the resonance frequency of the multilayer printed circuit board on which 0 is mounted is lower than the resonance frequency fx determined by only the bypass capacitor 110, the resonance frequency fx of the bypass capacitor 110 configured by L1 and C1 is a harmonic of the driving frequency of the IC. higher than fa.

[0014] fx = 1 / (2π√ (L1 · C1)) (1) fy = 1 / (2π√ ((L1 + L2) C1)) (2) L2> L1 ... (3) here, C1: Capacitance component of bypass capacitor 110 L1: Inductance component of bypass capacitor 110 L2: An inductance component of the power supply pattern surface S.

In this way, by optimizing the inductance of the power supply pattern surface S and the constant of the bypass capacitor 100, by setting fa ≦ fx <110 MHz with respect to the harmonic frequency fa of the IC100, the power feeding seen from the IC100 is obtained. The impedance can be minimized and the radiated electromagnetic noise can be minimized. Further, by setting fy <76 MHz, the resonance frequency at which the power supply impedance seen from the IC 100 is maximum can be set to 76 MHz or lower, and radiated electromagnetic noise of 76 MHz or higher can be reduced.

Embodiment 2. FIG. 2 is a diagram for explaining the structure of the multilayer printed circuit board according to the second embodiment of the present invention. In this embodiment, an IC is mounted on a multilayer printed circuit board having a power pattern surface S and a ground pattern surface G.
100 and two bypass capacitors 11
0 and 120 are mounted near the IC 100. The bypass capacitors 110 and 120 are inserted between the power supply pattern surface S and the ground pattern surface G. The capacitance component of each bypass capacitor 110, 120,
Inductance components are C1 and L as shown
1, indicated by C2 and L3. The power supply pattern surface S has an elongated shape so as to have inductances L4 and L5 with respect to the bypass capacitors 110 and 120, respectively.

First, of the harmonics of the driving frequency of the IC 100, the frequency f included in the FM band (76 to 110 MHz)
Calculate b and fc. However, fb> fc. In this embodiment, the case where there are two frequencies included in the FM band (76 to 110 MHz) will be described.

Next, fβ <fb ≦ fα <110 MHz,
L having resonance frequencies fα, fβ, fγ, fζ satisfying 76 MHz <fc ≦ fγ <fβ, fζ <76 MHz
1, C1, L3, C2, L4, L5 are the following (4),
It is determined as shown in equations (5), (6), (7), (8), and (9). In the case of resonating along the routes a and c shown in FIG.
The resonance frequency of the multilayer printed board viewed from the side of 100 is minimized, and the radiated electromagnetic noise is minimized. When resonating along the paths of b and d shown in FIG. 2, the resonance frequency of the multilayer printed board viewed from the IC 100 side becomes maximum and the radiated electromagnetic noise becomes maximum.

[0019] fα = 1 / (2π√ (L1 · C1)) (4)   fβ = 1 / (2π√ ((L1 + L3 + L4) (C1 ・ C2 / (C1 + C2)))                                                           ... (5) fγ = 1 / (2π√ ((L3 + L4) (C2)) ... (6) fζ = 1 / (2π√ ((L3 + L5) (C2)) ... (7)   (L1 + L3 + L4) (C1 ・ C2 / (C1 + C2)) <(L3 + L4) (C2)                                                           ... (8) L5> L4 ... (9)

In this way, by optimizing the inductance of the power supply pattern surface S and the constants of the bypass capacitors 110 and 120, the harmonic frequency f of the IC 100 is
For b and fc, fβ <fb ≦ fα <110 MHz,
By setting 76 MHz <fc ≦ fγ <fβ, the IC
The feed impedance seen from 100 can be minimized, and the radiated electromagnetic noise can be minimized.

Further, by setting fζ <76 MHz, the resonance frequency at which the power feeding impedance seen from the IC100 becomes maximum can be set to 76 MHz or less, and 76 MHz
Radiated electromagnetic noise of z or more can be reduced.

Even if there are three or more harmonics of the driving frequency of the IC included in the FM band (76 to 110 MHz),
It goes without saying that the number of bypass capacitors may be increased to apply the above idea.

[0023]

As described above, according to the present invention, a bypass capacitor is inserted between the power supply pattern surface and the ground pattern surface near the IC in the vicinity of the IC, and the power supply pattern surface near the IC is elongated. In the multilayer printed circuit board, the inductance component L1 and the capacitance included in the bypass capacitor are provided between the highest frequency of the harmonics of the IC included in the FM broadcast frequency band and the maximum frequency of the FM broadcast frequency band. Resonance frequency (f = 1 / (2π√ (L1
Since the multilayer printed circuit board is characterized in that the bypass capacitor is configured so that
Less than the maximum frequency of FM broadcasting frequency band among harmonics of C
(If the frequency band for FM broadcasting is 76 to 110 MHz, 1
It is possible to reduce the radiated electromagnetic noise of the highest harmonic at 10 MHz or less).

Further, since the inductance component L2 of the power supply pattern surface is larger than the inductance component L1 included in the bypass capacitor, it is less than the maximum frequency of the FM broadcasting frequency band (F
110 if the frequency band for M broadcasting is 76 to 110 MHz
It is possible to reduce the radiated electromagnetic noise of the harmonic with the highest frequency in (MHz or less).

Further, in a multilayer printed circuit board in which a bypass capacitor is inserted between the power supply pattern surface and the ground pattern surface near the IC near the IC, and the power supply pattern surface near the IC is elongated, the bypass capacitor is used as the bypass capacitor. The resonance frequency (f calculated by the included inductance component L1 and capacitance component C1 and the inductance component L2 of the elongated power source pattern surface
= 1 / (2π√ ((L1 + L2) C1))) is equal to or lower than the minimum frequency of the FM broadcasting frequency band, and the bypass capacitor and the elongated power source pattern surface are configured. Therefore, among the IC harmonics, the frequency band for FM broadcasting (for example, 76 to 11
It is possible to reduce radiated electromagnetic noise of a harmonic wave of 0 MHz).

An IC included in the frequency band for FM broadcasting
There are two higher harmonics, and two bypass capacitors are inserted between the power supply pattern surface near the IC and the ground pattern surface in the vicinity of the IC, and the shape of the power supply pattern surface near the IC is elongated. In, the first bypass capacitor having the inductance component L1 and the capacitance component C1 is connected to the inductance component L3.
And a second bypass capacitor having a capacitance component C2, inserted closer to the IC, between the higher harmonic frequency of the IC harmonics and the maximum frequency of the FM broadcast frequency band, Resonance frequency (f = 1 / (2
π√ (L1 · C1))) and the frequency of the lower harmonic of the IC harmonics is the resonance frequency (f
= 1 / 2π√ ((L3 + L4) (C2)) (where L4 is the inductance component of the power supply pattern surface between the two bypass capacitors) and the resonance frequency (f = 1 / 2π√ ((L1 + L3 + L
4) (C1 · C2 / (C1 + C2))) and the resonance frequency (f = 1 / (2π√ ((L3 + L5) (C2)) (where L5 is the power supply on the power supply side of the two bypass capacitors). A multilayer printed circuit board characterized in that the first and second bypass capacitors and the elongated power source pattern surface are configured so that the inductance component of the pattern surface) is equal to or less than the minimum frequency of the frequency band for FM broadcasting. Therefore, radiated electromagnetic noise can be reduced when the harmonics of a plurality of ICs are included in the FM broadcast frequency band (eg, 76 to 110 MHz).

Further, since the inductance component L4 between the first and second bypass capacitors on the power supply pattern surface is smaller than the inductance component L5 on the power supply side of the two bypass capacitors, a plurality of ICs can be used. Harmonics are frequency bands for FM broadcasting (for example, 76-
(110 MHz), the radiated electromagnetic noise can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration of a multilayer printed circuit board according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a configuration of a multilayer printed board according to a second embodiment of the present invention.

[Explanation of symbols]

100 IC, 110, 120 bypass capacitors,
S power pattern surface, G ground pattern surface.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiro Yamanaka             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Yoshio Igawa             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F term (reference) 5E346 AA60 BB03 BB06 FF45 HH04

Claims (5)

[Claims] 1. A bypass capacitor is inserted between the power supply pattern surface and the ground pattern surface near the IC in the vicinity of the IC,
Further, in the multilayer printed circuit board in which the shape of the power source pattern surface near the IC is made elongated, the highest frequency of the harmonics of the IC included in the FM broadcast frequency band and the maximum frequency of the FM broadcast frequency band In between, the inductance component L1 included in the bypass capacitor
And the resonance frequency calculated by the capacitance component C1
(f = 1 / (2π√ (L1 · C1))) A multilayer printed circuit board characterized in that the above bypass capacitor is configured. 2. The multilayer printed circuit board according to claim 1, wherein the inductance component L2 of the power supply pattern surface is larger than the inductance component L1 included in the bypass capacitor. 3. A bypass capacitor is inserted near the IC between the power supply pattern surface and the ground pattern surface near the IC,
Further, in a multilayer printed board in which the shape of the power supply pattern surface near the IC is elongated, the inductance component L1 and the capacitance component C1 included in the bypass capacitor and the inductance component L2 of the elongated power supply pattern surface are calculated. Resonance frequency (f = 1
/ (2π√ ((L1 + L2) C1))) is configured such that the bypass capacitor and the elongated power source pattern surface are configured such that the frequency is equal to or lower than the minimum frequency of the FM broadcasting frequency band. 4. There are two harmonics of the IC included in the frequency band for FM broadcasting, and a bypass capacitor is provided between the power supply pattern surface and the ground pattern surface near the IC in the vicinity of the IC.
A multi-layer printed circuit board in which the shape of the power source pattern surface near the IC is elongated, and a first component having an inductance component L1 and a capacitance component C1.
Is inserted closer to the IC than the second bypass capacitor having the inductance component L3 and the capacitance component C2, and the higher harmonic frequency of the higher harmonics of the IC and the FM broadcasting frequency are inserted. Resonance frequency (f = 1 / (2π√
(L1 · C1))) and the frequency of the lower harmonic of the IC harmonics is the resonance frequency (f = 1
/ 2π√ ((L3 + L4) (C2)) (where L4 is the inductance component of the power supply pattern surface between the two bypass capacitors) and the resonance frequency (f = 1 / 2π√ ((L1 + L3 + L4)
(C1 · C2 / (C1 + C2))) and the resonance frequency (f = 1 / (2π√ ((L3 + L5) (C2))) (however, L5
Is the first and second bypass capacitors and the elongated power supply pattern surface such that the inductance component of the power supply pattern surface on the power supply side of the two bypass capacitors is less than or equal to the minimum frequency of the FM broadcast frequency band. A multilayer printed circuit board characterized by the above. 5. An inductance component L4 between the first and second bypass capacitors on the surface of the power supply pattern.
Is smaller than the inductance component L5 on the power supply side of the two bypass capacitors, the multilayer printed board according to claim 4.