JPS6233302Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a multilayer ceramic capacitor. Demand for multilayer ceramic capacitors has been increasing in recent years as an essential component for making electronic devices and circuits faster and more compact with high reliability. The reasons for this are: 1 High-frequency multilayer ceramic capacitors with large capacitance values are superior to conventional tantalum capacitors,
It can be made smaller than other capacitors such as aluminum electrolytic capacitors and film capacitors. 2 Due to the structure of the electrode surface, internal inductance is smaller than other capacitors. For this reason, the series resonance frequency is higher than that of other capacitors (the equivalent circuit of a capacitor is shown in Figure 1,
It is expressed as a series combination of resistance R and intance L, and the series resonance frequency is

It is given by the value of [Formula]. ), making it suitable for use in high frequency ranges. 3. The equivalent series resistance of multilayer ceramic capacitors at high frequencies is smaller than that of other capacitors. For this reason, there is less voltage drop and less heat generation than when using other capacitors. Therefore, incorporating multilayer ceramic capacitors into electronic devices and circuits not only improves power efficiency, but also has fewer problems due to heat generation, so high reliability can be obtained even when mounted compactly. There are many advantages such as: However, on the other hand, the equivalent series resistance value of the laminated ceramic capacitor may be too small, and in this case, it also acts as a drawback.
For example, by connecting a multilayer ceramic capacitor and a resistance element in series, the equivalent series resistance value that is insufficient with the multilayer ceramic capacitor alone must be compensated for, and the equivalent series resistance value must be made to be similar to the equivalent series resistance value of other capacitors. There are cases where it cannot be used. Below, we will explain a case where unsatisfactory results are caused because the equivalent series resistance value is too small, and consider ways to solve the problem. Feedback technology is indispensable for modern electronic circuits, and it is no exaggeration to say that the idea of feedback is utilized in any electronic circuit to stabilize the circuit. The feedback circuit is normally constructed as shown in FIG. That is, input signal V ₁ with gain μ()
When attempting to amplify the output _V2 signal with as little distortion as possible using an amplifier with a It composes. This β circuit is usually called a feedback circuit. The circuit becomes unstable when the two conditions that the phase angle arg(μβ) of the gain μβ is |arg(μβ)|≧180° and |μβ|≧1 are simultaneously satisfied.
Therefore, if the circuit design result shows that the phase exceeds -180° at frequency ₁ where |μβ| = 1 (i.e. OdB), as shown by the broken line a in Figure 3, |
At the frequency where μβ|=1 |arg(μβ)|<180
It is necessary to compensate the amplitude characteristics or phase characteristics so that the angle becomes .degree. One method often used for this compensation is to cascade a phase delay circuit into a μ circuit or a β circuit having unstable characteristics, as shown in FIG. 4, for example. The voltage ratio of the phase delay circuit in Figure 4 is So, the amplitude characteristic is becomes.

[Formula] and when ω≪1/C(R ₁ +R ₂ ), |Vout/Vin|≒1. Also

[Formula], and when 1/C(R ₁ + R ₂ )≪ω≪1/CR ₂ , |Vout/Vin|≒1/ωC(R ₁ +R ₂ ), which is -6dB/octave It becomes a slope. Also

When [Formula] and when ω≫1/CR ₂ , |Vout/Vin|≈R ₂ /R ₁ +R ₂ , which is constant regardless of the frequency. Putting the above together, the amplitude characteristics and phase characteristics of the phase delay circuit are as shown in FIG. Therefore, by cascading a phase delay circuit into a μ circuit or a β circuit with unstable characteristics as shown in FIG. 3a, |μβ|=1 as shown by the solid line b in FIG. The phase rotation at frequency ₁ becomes
It can be converted into a stable circuit with an angle of less than 180°. In this case, the constants of R ₁ , R ₂ , and C of the phase delay circuit can be appropriately selected. This method compensates by sacrificing some gain in the high frequency range, so it has the disadvantage that the bandwidth is narrower than before compensation, but it is often used because it is easy to design and operates stably. . It has been explained above that the phase delay circuit shown in FIG. 4 is an effective circuit in stabilizing the feedback circuit. As can be seen from the above explanation, in order to stabilize an electronic circuit using feedback technology combined with a phase delay circuit, as the frequency of the electronic circuit increases, the capacitance value C of the capacitor constituting the phase delay circuit It is necessary to select the resistance and capacitance so that the product with the resistance value R ₂ is smaller. Also, depending on the frequency range of the electronic circuit, by using the equivalent series resistance of a capacitor as _R2 , it is possible to form a phase delay circuit without separately preparing a resistance element called _R2 . I also understand that. The fact that the required phase delay circuit can be formed by replacing the equivalent series resistance of a capacitor without separately preparing a resistor element called R ₂ allows for high-density packaging and cost reduction of electronic circuits, which are rapidly required these days. This is a huge benefit in promoting the In other words, the resistance element
Not only does the mounting space for R ₂ become unnecessary, but the man-hours required for mounting can also be saved. However, as mentioned above, the equivalent series resistance value of a multilayer ceramic capacitor is small, about a fraction of the equivalent series resistance value of other conventional capacitors, so the capacitor section of a phase delay circuit formed using other capacitors is To replace the multilayer ceramic capacitor with a multilayer ceramic capacitor, in order to equalize the product of the capacitance value C and the resistance value _R2 described above, it is necessary to connect the multilayer ceramic capacitor and a resistance element in series while keeping the capacitance value C constant. Either the missing equivalent series resistance value must be compensated for by some other method, or an equivalent circuit configuration must be constructed using a separate capacitor or the like. However, this is undesirable because it destroys the advantage that a multilayer ceramic capacitor can be made smaller than other capacitors. Furthermore, even if adding a correction resistor or capacitor poses no problem in terms of space, it is not desirable in that it increases the number of man-hours required to implement it. Considering the above circumstances comprehensively, it becomes necessary to develop a multilayer ceramic capacitor with a high equivalent series resistance value. By the way, it is known that the equivalent series resistance of conventional multilayer ceramic capacitors is mainly composed of the resistances of the internal electrodes, external electrodes, and lead wires that constitute the multilayer ceramic capacitor. Therefore, one way to increase the equivalent series resistance of a multilayer ceramic capacitor is to increase the resistance value of the lead wire portion. This is because the lead wire can be made arbitrarily variable by selecting the appropriate length and cross-sectional area of a linear material with an appropriate specific resistance, and there is no need for the main body of a multilayer ceramic capacitor to obtain the desired resistance value. It has the advantage that it does not require any changes, and is also easy to implement. As is well known, the resistance R of a linear material has the relationship R=ρ·l/S between the resistivity ρ of the metal, the cross-sectional area S, and the length l. Therefore, if the shape of the lead wire is to be made as small as possible in order to realize high-density packaging, it is more efficient to select a material with a large resistivity and reduce the cross-sectional area. However, the cross-sectional area cannot be reduced to the point where the mechanical strength necessary for the lead wire is insufficient. This is because if the mechanical strength of the lead wire is insufficient, damage may occur, such as breakage of the lead wire or contact of the lead wire with other electrical signal lines such as the ground line. Therefore, the method of increasing the resistance value of the lead wire section to obtain the required equivalent series resistance must be carried out while also ensuring the mechanical strength of the lead wire. There are limits to choosing a small size. However, there is also a limit to selecting a long lead wire length, and excessively long lead wire lengths also hinder high-density packaging. The present invention solves these various problems, and includes providing at least one lead-out electrode section separate from the so-called external electrode in a part of the ceramic block section constituting the multilayer ceramic capacitor. A resistive material having a higher electrical resistance than either the internal electrode or the external electrode is connected between the corresponding external electrode and the extraction electrode part,
This multilayer ceramic capacitor is characterized in that at least one of the so-called lead wires comes out from this extraction electrode section. According to the present invention, the desired resistance can be achieved by adjusting it to an arbitrary value without using conventional lead wires, so the lead wires do not become inconvenient to handle and are also convenient in terms of handling. There is an advantage that the lead wires can be designed independently. Another important advantage of the present invention is that miniaturization of the product is not hindered. Hereinafter, the present invention will be explained in more concrete detail using Examples. FIG. 6 is for explaining one embodiment of the present invention, and FIG. 6A is a schematic diagram showing the outline of the structure when viewed from the side, and FIG. 6B is a schematic diagram showing the outline of the structure when viewed from the front. In the figure, 1 is a multilayer ceramic capacitor body with a shape of 14 mm x 12 mm x 5 mm, an equivalent series resistance of 1.1 mΩ, and a capacitance value of 200 μF, 2 is an external electrode of the multilayer ceramic capacitor, and 3 is a conductive adhesive such as solder. , 4 is a new mounting electrode of the present invention for attaching the lead wire, and 6 is a resistor newly constructed of the present invention, which is composed of a manganin wire having a shape of 0.2 mmφ x 4.4 mm, and adjusts the equivalent series resistance to a desired value. As for the materials, 5 is a lead wire made of a copper wire with a diameter of 0.8 mm, and 7 is a molded part having a shape of 18 mm x 18 mm x 10 mm. The multilayer ceramic capacitor of this example is
Developed as a capacitor for use in the phase delay circuit of 200KHz power supplies.It has electrical characteristics of equivalent series resistance of 15mΩ and capacitance of 200μF, and has good results when incorporated into the phase delay circuit. I got it. To replace a multilayer ceramic capacitor having an equivalent series resistance value equivalent to that of the multilayer ceramic capacitor of this embodiment with a multilayer ceramic capacitor of the so-called "increasing the resistance value of the lead wire portion to obtain the required equivalent series resistance" type: In order to obtain the required equivalent series resistance, it is necessary to attach lead wires of 35 mm length (the material is manganin wire, the same as in this example, and the wire diameter is 0.8 mmφ) to each of the two external electrodes. It is necessary to use a capacitor whose case size is approximately twice as large as that of the laminated ceramic capacitor of this embodiment. As is clear from the above examples, the multilayer ceramic capacitor of the present invention is an excellent product that meets its purpose and exhibits sufficient functions. In the above embodiment, the material and shape of the lead part are selected so that the resistance value of the lead part can be ignored, but the material and shape of the lead part are selected so that the desired resistance value is shared by the lead part. It goes without saying that the laminated ceramic capacitor of the present invention can be constructed by selecting the shape.

[Brief explanation of drawings]

Figure 1 is an equivalent circuit of a capacitor, Figure 2 is a block diagram of a feedback circuit, Figure 3 is an explanatory diagram of the gain and phase of the feedback circuit, Figure 4 is a basic configuration diagram of a phase delay circuit, and Figure 5 is a phase diagram. FIG. 6, a diagram showing the gain and phase of a delay circuit, is a schematic diagram for explaining an embodiment of the present invention. In the figure, 1 is the main body of a multilayer ceramic capacitor, 2 is an external electrode, 3 is a conductive adhesive such as solder, 4 is a take-out electrode newly installed in this invention, 5 is a lead wire, 6 is a resistance material newly installed in this invention, 7 indicates a mold part, respectively.

Claims (1)

[Scope of utility model registration request] At least one lead-out electrode part separate from the so-called external electrode is provided in a part of the ceramic block part constituting the multilayer ceramic capacitor, and the space between the corresponding external electrode and the lead-out electrode part is an internal electrode or an external electrode. A multilayer ceramic capacitor characterized in that the capacitor is connected with a resistive material having a higher electrical resistance than either of the lead wires, and at least one of the so-called lead wires comes out from the lead electrode part.