JP2002232110A - Circuit board for mounting laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board capable of reducing a vibration sound which is excited by ripple component to be applied to a laminated ceramic capacitor. SOLUTION: The circuit board comprises first and second ceramic capacitors 1a, 1b disposed so that the capacitors 1a, 1b are aligned at one surface side of the circuit board 5, and constituted so that the amplitude operation of vibration waves propagated to the board by generating in dielectric layers of the respective capacitors, by the ripple component based on charging/discharging to be applied to the first and second capacitors becomes a substantially opposite phase equal amplitude relation at one surface side of the board. As a result of this constitution, the vibration sound generated by the exciting of the board 5 can be remarkably reduced by a large extent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor having a structure in which a multilayer ceramic capacitor is mounted on a circuit board and capable of reducing vibration noise excited by a charge / discharge ripple component applied to the ceramic capacitor. The present invention relates to a circuit board on which is mounted.

[0002]

2. Description of the Related Art For example, in a bypass circuit used for a bias power supply circuit for a variable load, an aluminum electrolytic capacitor has been used as a capacitor for power supply bypass. However, with the demand for miniaturization of electronic circuits and electronic devices, tantalum capacitors that can obtain the same capacitance as aluminum electrolytic capacitors in a smaller size than aluminum electrolytic capacitors are frequently used in power supply bypass circuits and the like. .

[0003] However, the above-mentioned tantalum capacitors are expensive, and in recent years, the demand for miniaturization and energy saving of electronic circuits and electronic equipment has further increased, and most of the capacitors used in this kind of electronic circuits have been increased. There is a trend to use multilayer ceramic capacitors. This multilayer ceramic capacitor has characteristics of being small in size and being excellent in reliability and durability, and it is considered that the demand thereof is rapidly increasing for such a reason.

FIG. 6 is a sectional view showing a state in which the above-mentioned multilayer ceramic capacitor is mounted on a circuit board. The ceramic capacitor 1 has a configuration in which dielectric layers 2 and internal electrodes 3 are alternately stacked. Further, a pair of external electrodes 4 are formed at both ends thereof, and the internal electrodes 3 are alternately connected in parallel to the pair of external electrodes 4, and the outer shell is formed in a substantially rectangular parallelepiped shape. The multilayer ceramic capacitor 1 is connected to the circuit board 5
The pair of external electrodes 4 are respectively conductively connected to the lands 6 formed on the surface of the substrate by means such as soldering and mounted on the circuit board 5.

On the other hand, FIG. 7 shows an example of a partial circuit configuration when the above-mentioned ceramic capacitor is used as a bypass capacitor in a bias power supply circuit, for example. In the configuration shown in FIG. 7, the positive terminal of DC power supply E is connected to the collector terminal of npn transistor Q, and its base terminal is supplied with a bias potential obtained by dividing DC power supply E by resistors R2 and R3. You. Also,
The emitter terminal of the transistor Q has an emitter resistor R1.
Is connected in parallel with the emitter resistor R1, that is, the multilayer ceramic capacitor 1 described with reference to FIG. The terminal voltage of the bypass capacitor 1 connected to the emitter terminal of the transistor Q is supplied to a variable load L such as an oscillation circuit.

According to the circuit example shown in FIG. 7, the bias potential applied to the base terminal of the transistor Q
The transistor Q operates as an emitter follower. As a result, the current from the DC power supply E flows to the resistor R1 via the collector and the emitter of the transistor Q,
A DC terminal voltage is generated in the bypass capacitor 1 connected in parallel with this. With this configuration, the variable load L
Is formed as a bias power supply circuit.

[0007]

Incidentally, since the above-mentioned multilayer ceramic capacitor uses a high dielectric constant material as a dielectric material, it is necessary to apply a DC voltage as shown in FIG. When charging / discharging is performed, an expansion / contraction operation occurs, and vibration corresponding to a fluctuating load occurs. This vibration is
When the capacitor has a large dielectric constant, the shape of the capacitor is large, and the charging / discharging current is large, it tends to appear more remarkably.

In a bypass circuit of a bias power supply circuit, a multilayer ceramic capacitor having a relatively large shape and a large capacitance is used, and a large charge / discharge current increases the degree of occurrence of this kind of vibration. . Further, the vibration generated in the multilayer ceramic capacitor may be transmitted to a circuit board on which the capacitor is mounted, and the circuit board may resonate and be amplified.
That is, there is a problem that the circuit board is excited by the vibration of the capacitor, thereby generating an unpleasant audible sound.

In particular, when the above-described configuration is used for a mobile phone, the sound pressure of the audible sound has a great effect on the ears, and thus the user is suspicious of malfunction. You will have factors that reduce value.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a multilayer ceramic capacitor capable of reducing the charging / discharging current of a ceramic capacitor and the vibration noise excited by a generated ripple component. It is an object to provide a mounted circuit board.

[0011]

Means for Solving the Problems In a circuit board according to the present invention which has been made to solve the above-mentioned problems,
A circuit board mounted with a multilayer ceramic capacitor in which internal electrodes are alternately laminated in a dielectric layer made of ceramic and alternate internal electrodes facing each other in the dielectric layer are connected to a pair of external electrode terminals, respectively. At least the first and second ceramic capacitors are arranged so as to be arranged on one side of the circuit board, and are generated in the dielectric layer by charge / discharge currents and ripple components of the first and second ceramic capacitors. The amplitude operation of the vibration wave transmitted to the circuit board is configured to have a substantially opposite phase equal amplitude relationship on one surface side of the circuit board.

In this case, it is desirable that the equivalent circuit formed by at least the first and second ceramic capacitors has a relation in which the capacitance values of the respective capacitors are added when viewed from the load side.

Further, two or more capacitors are connected in parallel as the first ceramic capacitor,
Two or more capacitors are connected in parallel as the second ceramic capacitor, and the capacitors are arranged in a row direction and a column direction on one surface side of a circuit board, and are respectively adjacent to each other in a row direction and a column direction. In some cases, the amplitude operation of the vibration wave transmitted from the capacitor to the circuit board may be substantially in opposite phase and equal amplitude relation on one surface side of the circuit board.

In a preferred embodiment,
One of the external electrode terminals of the first and second ceramic capacitors is commonly connected, and a ripple is provided between the common connection point and the other external electrode terminal of the first and second ceramic capacitors. Each component is configured to be generated and applied. In another preferred embodiment, the ripple component generated between the external electrodes of the first ceramic capacitor is applied between the external electrodes of the second ceramic capacitor via a phase inverting circuit to charge the capacitor. It is configured to discharge.

In the above-mentioned combination,
It is desirable that the capacitance values of the first ceramic capacitor and the second ceramic capacitor are substantially equal. Further, it is desirable that the voltage values of the ripple components generated in the first ceramic capacitor and the second ceramic capacitor are made substantially equal. In the above-described mounting configuration, the first and second ceramic capacitors can be suitably used as bypass capacitors of the bias power supply circuit.

According to the circuit board on which the multilayer ceramic capacitor having the above configuration is mounted, the first and second ceramic capacitors are arranged so as to be arranged on one side of the circuit board, and each capacitor is charged and discharged by a variable load. Since the amplitude operation of the generated vibration wave is substantially in opposite phase on one surface side of the circuit board, the vibration wave transmitted to the circuit board from each capacitor can be canceled. As a result, generation of audible sound having a large sound pressure can be effectively reduced.

On the other hand, in the case where the equivalent circuit constituted by the first and second ceramic capacitors is configured such that the capacitance values of the respective capacitors are added when viewed from the load side, the first and second ceramic capacitors may be used. The capacitance of each of the second capacitors can be substantially halved. Therefore,
It is possible to further reduce the degree to which the first and second capacitors are charged and discharged and excited by the ripple.

Further, each of the first and second ceramic capacitors is constituted by connecting two or more capacitors in parallel, and the capacitors are arranged in a row direction and a column direction on one surface side of the circuit board. When the amplitude operation of the vibration waves generated by the respective capacitors adjacent in the row direction and the column direction is configured to have a substantially opposite phase relationship on one surface side of the circuit board, the vibration waves transmitted from the respective capacitors to the circuit board are generated. It can be offset as well. As a result, generation of audible sound having a large sound pressure can be effectively reduced.

In this case, since the first capacitor and the second capacitor are each configured by connecting two or more capacitors in parallel, it is possible to reduce the capacitance value of each capacitor. By
Each capacitor can further reduce the degree of excitation by charge / discharge and ripple components. Moreover,
Since the amplitude operation of the vibration wave generated in each capacitor has an opposite phase relationship to each other in the row and column directions,
This can contribute to further reducing the degree of excitation applied to the circuit board.

As one means for realizing the above-mentioned operation, one of the external electrode terminals of the first and second ceramic capacitors is connected in common, and the common connection point is connected to the first and second ceramic capacitors. This can be realized by a configuration in which a ripple component is applied between the ceramic capacitor and the other external electrode terminal. This configuration utilizes, for example, ripple voltages of opposite phases generated by a fluctuating load on the power supply side and the ground side when viewed from the emitter of the transistor, and applies a ripple voltage in a reverse phase relationship to the first and second capacitors. It can be realized by applying. As a result, the charging and discharging of the first and second capacitors with respect to the load fluctuation also have an opposite phase relationship.

Further, as another means for realizing the above-mentioned operation, a ripple component applied between external electrodes of the first ceramic capacitor is supplied to the outside of the second ceramic capacitor via a phase inversion circuit. It can also be realized by a configuration in which voltage is applied between the electrodes. This configuration uses an inverting input type feedback amplifier as a phase inverting circuit and uses a phase inverting circuit with a voltage gain of “−1” by setting a resistance value ratio between an input resistor and a feedback resistor to “1”. it can.

In each of the above-described configurations, the first
By selecting the capacitance values of the first and second ceramic capacitors to be approximately equal to each other, it is possible to appropriately balance the vibrations of the opposite phases generated by the first and second capacitors, and the vibrations are transmitted to the circuit board. The amplitude operation can be effectively canceled. Further, in each of the above-described configurations, the voltage value of the ripple component applied to the first and second ceramic capacitors is controlled so as to be substantially the same, so that the voltage is similarly generated from the first and second capacitors. It is possible to suitably balance the vibration in the opposite phase, and to effectively cancel the amplitude operation transmitted to the circuit board.

In addition, when the above-described configuration is used as a bypass capacitor for a bias power supply with respect to a variable load, vibration noise generated from a bypass ceramic capacitor with a large variable load requiring a relatively large capacitance is generated. It can contribute to the effective reduction.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit board on which a multilayer ceramic capacitor according to the present invention is mounted will be described below with reference to the drawings. FIG. 1 is a perspective view showing a first embodiment in which a multilayer ceramic capacitor is mounted on a circuit board. In the configuration shown in FIG. 1, the first and second capacitors are mounted close to each other on one surface of the circuit board. FIG. 2A shows this state as viewed from above. In this embodiment, the first and second capacitors 1a and 1b have the same specifications (the same capacitance and the same outer shape).
Each of the lands 6 is conductively connected by soldering (not shown) and mounted on the circuit board 5.

In the mounting structure shown in FIGS. 1 and 2A, the first and second capacitors 1a and 1b are
It is incorporated in the circuit configuration shown in FIG. This circuit configuration shows a partial configuration example of the bias power supply,
The first and second capacitors 1a and 1b are used as bypass capacitors.

In the circuit configuration shown in FIG.
The positive terminal of the DC power supply E is connected to the collector terminal of the npn transistor Q, and its base terminal is supplied with a bias potential for load fluctuation L obtained by dividing the DC power supply E by the resistors R2 and R3. An emitter resistor R1 is connected to the emitter terminal of the transistor Q, and a first bypass capacitor 1a is connected in parallel with the emitter resistor R1. A second bypass capacitor 1b is connected between the collector terminal and the emitter terminal of the transistor Q, and the common connection point of the first and second capacitors 1a and 1b, that is, the emitter terminal of the transistor Q is , And a variable load L.

The circuit configuration shown in FIG.
It can be represented by the equivalent circuit shown in FIG. That is,
The first and second capacitors 1a and 1b are connected in series between the DC power supply E, and a potential obtained by dividing the bias voltage e by the resistors R4 and R5 is applied to a connection point between the first and second capacitors 1a and 1b. In addition, it can be seen that the variable load L is connected to the connection point. According to this configuration, one of the electrode terminals of the first and second capacitors is commonly connected, and the common connection point is connected to the first and second capacitors.
Between the other electrode terminal of the capacitor and the ripple component due to charging and discharging of the variable load L.

That is, the first and second capacitors 1a, 1a,
To 1b, ripple components due to charge and discharge are applied in opposite phase relation to each other. In addition, the equivalent circuit formed by the first and second ceramic capacitors has a relationship in which the capacitance values of the respective capacitors are added when viewed from the variable load L side, and is added to the first and second capacitors. The voltage amplitude values of the ripple components are made substantially equal. Therefore, in the first and second capacitors 1a and 1b in the state shown in FIG.
The amplitude operation of the vibration wave transmitted to the device is substantially in a reverse phase relationship, and the magnitude of the amplitude is also substantially equal.

As a result, on the circuit board 5, the excitation effect due to the vibration of each of the capacitors 1a and 1b is canceled, and the degree of generation of audible sound can be greatly reduced. Then, since the capacitance values of the capacitors are equivalently added when viewed from the side of the variable load L, when the capacitors are used as bypass capacitors in the bias power supply circuit as in this embodiment, sufficient A simple bypass operation can be obtained. In other words, each of the capacitors may have a capacitance that is １ ／ of the capacitance required as a bypass capacitor. Therefore, the level of the vibration wave generated by each capacitor can be suppressed, and together with the above-described effect of the canceling action,
The degree to which the circuit board receives the excitation and generates an audible sound can be further reduced.

FIG. 4 shows a second embodiment in which the multilayer ceramic capacitor is mounted on a circuit board. In this embodiment, two capacitors are connected in parallel as the first and second ceramic capacitors. That is, as shown in FIG. 4A, the first capacitors 1a-1 and 1a-2 are connected in parallel with each other, and further connected in parallel to the emitter resistor R1. , 1b-1, 1
b-2 is connected between the collector terminal and the emitter terminal of the transistor Q in a state of being connected in parallel. The other configuration is the same as the configuration in FIG. In this case, the above-mentioned capacitors 1a-1, 1a-2, 1b-1, 1b-2
Have the same specifications (the same capacitance and the same outer shape).

FIG. 4B shows an equivalent circuit in this case. As described above with reference to FIG. 3, two parallel-connected capacitors 1a-1 and 1a-2 as first capacitors and two parallel-connected capacitors 1b as second capacitors are provided. -1, 1b
To -2, charge / discharge ripple components having mutually opposite phases are applied. These capacitors are mounted close to each other on one surface of a circuit board as shown in FIG. That is, the capacitors are arranged in the row direction and the column direction on one surface side of the circuit board, and the amplitude operation of the vibration wave transmitted from the respective capacitors adjacent in the row direction and the column direction to the circuit board is determined by the circuit board. On the one surface side so as to have a substantially opposite phase relationship.

For example, in FIG.
The amplitude operation exerted on the circuit board by the vibration wave at a-1 is opposite to the amplitude operation exerted by the vibration wave on the capacitor 1b-1 adjacent in the row direction on the circuit board.
Further, the amplitude operation of the vibration wave of the capacitor 1a-1 on the circuit board is opposite to the amplitude operation of the vibration wave of the capacitor 1b-2 adjacent in the column direction on the circuit board. This relationship is made similarly from the viewpoint of any capacitor.

According to the above-described structure, each of the ceramic capacitors may have a capacitance of 1/4 of the capacitance required as a bypass capacitor. Therefore, the level of the vibration wave generated by each capacitor can also be suppressed, and together with the effect of the vibration wave canceling effect on the circuit board as described above, the circuit board is excited to generate an audible sound. The degree can be further reduced.

In the embodiment shown in FIGS. 4 and 2B, the first and second capacitors are:
Although two ceramic capacitors are arranged in parallel in each case, three or more ceramic capacitors may be arranged in parallel with each other. In this case, it is desirable to use capacitors having the same specifications, but it is not necessarily limited to this. Also, the number of ceramic capacitors assembled as the first and second capacitors need not necessarily be the same as each other.

FIG. 5 shows a third embodiment in which the multilayer ceramic capacitor is mounted on a circuit board. In this embodiment, the ripple component applied between the external electrodes of the first ceramic capacitor is applied between the external electrodes of the second ceramic capacitor via a phase inversion circuit. FIG. 5A shows an embodiment in which the first capacitor 1a is used as a bypass capacitor of a bias power supply circuit.

In the configuration shown in FIG. 5A, the positive terminal of DC power supply E is connected to the collector terminal of npn transistor Q, and DC power supply E is divided at its base terminal by resistors R2 and R3. The bias potential for the changed load L is supplied. An emitter resistor R1 is connected to the emitter terminal of the transistor Q. A first bypass capacitor 1 is connected in parallel with the emitter resistor R1.
a is connected. The terminal voltage of the bypass capacitor 1a connected to the emitter terminal of the transistor Q is supplied to the variable load L.
A phase inversion circuit 11 is connected to the emitter terminal of the transistor Q, and a second bypass capacitor 1b is connected through the phase inversion circuit 11.

FIG. 5B shows an example in which the phase inversion circuit 11 is realized using an operational amplifier (hereinafter, referred to as an operational amplifier). That is, the non-inverting input terminal of the operational amplifier 11 is connected to the ground as a reference potential point, and the inverting input terminal of the operational amplifier 11 has
A ripple signal is supplied from the emitter terminal of the transistor Q via the input resistor R6. A feedback resistor R7 is connected from the output terminal of the operational amplifier 11 to the inverting input terminal, and the output terminal of the operational amplifier 11 is connected to the second capacitor 1b. In this case, since the operational amplifier becomes a capacitive load, a measure for preventing oscillation is desirably taken.

In the circuit example shown in FIG. 5B, the resistance ratio between the input resistor R6 and the feedback resistor R7 is "1" (R6
= R7), so that the gain between input and output is "-
1 ". According to this configuration, the current input to and output from the inverting input terminal of the operational amplifier 11 is inverted in phase according to the ripple component of the emitter terminal of the transistor Q. The second capacitor 1 in the form
b acts to charge and discharge. The first and second capacitors 1a and 1b are arranged and mounted on a circuit board as shown in FIGS. 1 and 2A.

Therefore, also in this configuration, the same operation and effect as those described based on the embodiment shown in FIG. 3 can be obtained, and the circuit board receives the vibration from the ceramic capacitor to generate an audible sound. It is possible to reduce the degree to which it is performed. In the embodiment shown in FIG.
As the first and second capacitors, two or two or more capacitors can be connected in parallel. In this case, the configuration described with reference to FIG. 2B can be used for the arrangement of the capacitors.

[0040]

As is apparent from the above description, according to the circuit board on which the multilayer ceramic capacitor according to the present invention is mounted, the first and second ceramic capacitors are arranged so as to be arranged on one side of the circuit board. Then, the amplitude operation of the vibration wave generated in the capacitor due to the ripple component of the charge and discharge applied to the first and second ceramic capacitors and transmitted to the circuit board has a substantially opposite phase equal amplitude relationship on one surface side of the circuit board. With this configuration, vibration noise generated when the circuit board is excited can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a multilayer ceramic capacitor is mounted on a circuit board.

FIG. 2 is a plan view showing a state in which the multilayer ceramic capacitor is mounted on a circuit board.

FIG. 3 is a connection diagram showing a first circuit configuration example in which the capacitor is used as a bypass capacitor of a bias power supply circuit to a variable load in the mounting configuration of the capacitor shown in FIG. 1 or FIG. 2;

FIG. 4 is a connection diagram showing a second circuit configuration example.

FIG. 5 is a connection diagram showing a third circuit configuration example.

FIG. 6 is an enlarged sectional view showing a state in which the multilayer ceramic capacitor is mounted on a circuit board.

FIG. 7 is a connection diagram illustrating a configuration example of a conventional bias power supply circuit added to a variable load.

[Explanation of symbols]

 Reference Signs List 1 multilayer ceramic capacitor 1a, 1a-1, 1a-2 first capacitor 1b, 1b-1, 1b-2 second capacitor 2 dielectric layer 3 inner electrode 4 outer electrode 5 circuit board 6 land E DC power supply L fluctuation Load Q Transistor R1-R7 Resistor e Bias power supply

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Takashi Goto, Inventor 4-146-7, Yawatabara, Yonezawa-shi, Yamagata F-term in the Yonezawa Plant of Tohoku Pioneer Co., Ltd. (Reference) 5E336 AA04 AA11 BB01 CC32 CC53 GG11 GG15

Claims (8)

[Claims] 1. A circuit mounted with a multilayer ceramic capacitor in which internal electrodes are alternately laminated in a dielectric layer made of ceramic and alternate internal electrodes facing each other in the dielectric layer are connected to a pair of external electrode terminals, respectively. A substrate, wherein at least first and second ceramic capacitors are arranged so as to be arranged on one surface side of a circuit board, and a ripple component applied to the first and second ceramic capacitors causes the dielectric layer to have A circuit board mounted with a multilayer ceramic capacitor configured such that an amplitude operation of a vibration wave generated and transmitted to the circuit board has a substantially opposite phase equal amplitude relationship on one surface side of the circuit board. 2. The multilayer ceramic according to claim 1, wherein the equivalent circuit constituted by at least the first and second ceramic capacitors has a relation in which the capacitance values of the respective capacitors are added when viewed from the load side. Circuit board on which capacitors are mounted. 3. The first ceramic capacitor includes two or more capacitors connected in parallel, and the second ceramic capacitor includes two or more capacitors connected in parallel. Are arranged in the row direction and the column direction on one surface side of the circuit board, and the amplitude operation of the vibration wave transmitted from the respective capacitors adjacent in the row direction and the column direction to the circuit board is respectively on the one surface side of the circuit board. 3. A circuit board on which the multilayer ceramic capacitor according to claim 1 or 2 is configured to have a substantially opposite-phase equal amplitude relationship. 4. One of the external electrode terminals of the first and second ceramic capacitors is connected in common, and the common connection point is connected to the other external electrode terminal of the first and second ceramic capacitors. 4. A circuit board on which the multilayer ceramic capacitor according to claim 1, wherein a ripple component is applied between the circuit boards. 5. The apparatus according to claim 1, wherein a ripple component applied between external electrodes of said first ceramic capacitor is applied between external electrodes of said second ceramic capacitor via a phase inversion circuit. A circuit board on which the multilayer ceramic capacitor according to claim 3 is mounted. 6. The first ceramic capacitor and a second ceramic capacitor.
A circuit board on which the multilayer ceramic capacitor according to any one of claims 1 to 5 has a substantially same capacitance value. 7. The first ceramic capacitor and a second ceramic capacitor.
6. A circuit board mounted with the multilayer ceramic capacitor according to claim 1, wherein voltage amplitude values of ripple components applied to said ceramic capacitor are substantially equal. 8. A circuit board mounted with the multilayer ceramic capacitor according to claim 1, wherein said first and second ceramic capacitors are used as bypass capacitors in a bias power supply circuit for a variable load. .