JP2000232006A - Chip-type electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip-type electronic component as small surge countermeasures, in which the delay of a response to the change of an impressed voltage can be reduce, and an electrostatic capacity can be reduced. SOLUTION: A capacitor 1 is integrated with an SiC varister 5 to form an element main body 9, and the capacitor 1 and the SiC varister 5 are connected in parallel through outer electrodes 10 formed on the both edge faces. In this case, the SiC varister materials have a dielectric constant which is 10-30 and the composite capacitance of the varistor, so that the capacitor which is 100 pF or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a chip-type electronic component. In particular, the present invention relates to a chip-type electronic component including a varistor and a capacitor for protecting an electronic device or the like from a surge for surge suppression.

[0002]

2. Description of the Related Art In recent years, the development of semiconductor technology has greatly contributed to the progress of electronic devices, and the use of semiconductor elements such as ICs and LSIs has significantly reduced the size and performance of electronic devices. However, an electronic circuit including a semiconductor element is vulnerable to surge (abnormal voltage), and when a surge current flows through the semiconductor element, the electronic circuit may be broken.

In order to protect an electronic circuit from such a surge, varistors have been widely used.
A varistor is an element whose electric resistance changes non-linearly with respect to voltage. When connected in parallel with a semiconductor element or the like, the varistor absorbs surge flowing through the semiconductor element or the like. That is, a high electric resistance value is maintained during normal energization in which a voltage equal to or lower than a varistor voltage (a voltage when a current of 1 mA flows through the varistor) is applied to a semiconductor element or the like, while a surge occurs. When an abnormal voltage higher than the varistor voltage is applied to a semiconductor element, etc., the electric resistance value drops sharply, taking advantage of the non-linearity of the varistor. In the event of a surge, the surge current is bypassed to the varistor and absorbed. Etc. are protected.

[0004] Such a varistor for absorbing surge has a large non-linearity in electric resistance with respect to voltage and a large surge withstand capability (maximum surge current value that can be absorbed without destroying a semiconductor element or the like). A varistor is used. Recently, low-voltage type ZnO chip varistors having a laminated structure have been put into practical use. With the high-density mounting of electronic circuits and the reduction in driving voltage, components for preventing electrostatic surge such as semiconductor elements have been developed. As such, ZnO chip varistors are frequently used.

However, the response speed of the ZnO varistor, that is, the response speed of the change in the electric resistance to a rapid change in the voltage is not sufficient, and the ZnO varistor has a short response time to noise, for example, noise of a short wavelength whose cycle is 10 ns or less. Has a response delay, and the noise removing effect is not sufficient.

Therefore, a chip-type electronic component has been proposed in which a ZnO varistor and a capacitor are integrated and connected in parallel to compensate for the response speed of the varistor (Japanese Patent Application Laid-Open No. H10-125557). As shown in FIG. 8, the chip-type electronic component has external electrodes 28 provided on both end surfaces of an element body 27 on which a ZnO varistor 24 and a capacitor 21 are stacked. In the ZnO varistor 24, the varistor layer 25 is sandwiched between the internal electrodes 26. The internal electrodes 26 sandwiching the varistor layer 25 are alternately exposed on both end faces of the element body 27, and the exposed end faces of each of the internal electrodes 26 are connected to the external electrode. 28 is electrically connected. On the other hand, the capacitor 21 has a dielectric layer 22
The internal electrode 23 sandwiching the dielectric layer 22 is
The internal electrodes 23 are exposed alternately on both end surfaces of the element body 27.
Are electrically connected to the external electrodes 28.
As a result, as shown in the equivalent circuit of FIG. 9, the ZnO varistor 24 and the capacitor 21 are electrically connected in parallel through the external electrode 28.

The capacitor 21 connected in parallel to the ZnO varistor 24 has a function of absorbing the noise by passing the noise when the ZnO varistor 24 generates a fast rising noise which cannot respond by itself. As described above, by connecting the ZnO varistor 24 and the capacitor 21 in parallel, the disadvantages of the ZnO varistor 24 are maintained while maintaining the high voltage non-linearity of the electric resistance and the magnitude of the surge resistance, which are the advantages of the ZnO varistor 24. The delay in response to fast rising noise has been improved.
In addition, since the chip-type electronic component integrates the two components of the ZnO varistor 24 and the capacitor 21, it has contributed to further downsizing and cost reduction of the electronic device. This chip-type electronic component could also be used as a capacitor having a surge function.

[0008]

However, the varistor has the same structure as a capacitor, and the (apparent) relative dielectric constant of ZnO is as large as 100 to 500.
An nO varistor has a large capacitance. This Zn
Since a capacitor is connected in parallel to the O varistor,
The capacitance of the chip-type electronic component has a larger value.
For this reason, a high-frequency signal easily leaks through a chip type electronic component for surge suppression, and cannot be used for a signal line through which a high-speed signal passes.

In today's world where signal speeds are increasing, there is a demand for chip-type electronic components for surge suppression with a small response delay and a small capacitance under such technical background.

The present invention has been made to solve the above-mentioned technical problems, and an object of the present invention is to provide a chip-type electronic component having a small response delay to a change in applied voltage and a small capacitance. Is to provide.

[0011]

DISCLOSURE OF THE INVENTION The chip-type electronic component according to claim 1 is
In a chip-type electronic component in which a varistor and a capacitor are connected in parallel and integrated, a varistor material constituting the varistor is made of a low dielectric constant material containing SiC as a main component. In particular, the relative dielectric constant of the varistor material is 10 or more and 30 or more.
The following is desirable (claim 2).

Since the response speed of the SiC varistor used in the chip-type electronic component of the first aspect is faster than that of the ZnO varistor, even if the capacitance of the capacitor connected in parallel with the SiC varistor is reduced, high-speed noise can be prevented. As a result, it is possible to obtain a surge suppression component having no response delay. Further, since the SiC varistor mainly composed of SiC having a small relative dielectric constant is used, the capacitance of the varistor portion can be reduced. Therefore, the total capacitance (combined capacitance) of the SiC varistor and the capacitor can be reduced, and the device can be used as a surge countermeasure component that can support high-speed signal lines.

A third aspect of the present invention is the chip-type electronic component according to the first or second aspect, wherein a combined capacitance of the varistor and the capacitor is set to 100 pF or less.

In a chip-type electronic component using a conventionally used ZnO varistor, the total capacitance is 10%.
Although it is larger than 0 pF, a chip-type electronic component using a SiC varistor can reduce the total capacitance to 100 pF or less, and can be used as a surge suppression component suitable for a high-speed signal line.

According to a fourth aspect of the present invention, in the chip type electronic component according to the first, second or third aspect, the varistor and the capacitor are laminated and integrated by simultaneous firing.

In this embodiment, since the varistor and the capacitor are fired simultaneously, the number of firing steps can be reduced as compared with the case where the varistor and the capacitor are fired separately.
The manufacturing process of the chip-type electronic component can be simplified.

[0017] Further, the embodiment of claim 5 is based on claim 1,
4. The chip-type electronic component according to 2 or 3, wherein the fired varistor and the fired capacitor are integrated by bonding.

In this embodiment, the fired varistor and the fired capacitor are integrated by bonding.
There is no fear that the chip-type electronic component will be warped or distorted by firing, unlike the case where the varistor and the capacitor are fired simultaneously.

[0019]

(First Embodiment) FIG. 1 is a sectional view showing a structure of a chip type electronic component for surge suppression according to an embodiment of the present invention. In this chip-type electronic component, the element body 9 is formed by stacking the SiC varistor 5 covered with the glass film 8 on the capacitor 1 covered with the glass film 4 and integrating them by bonding. Are formed with external electrodes 10 on both end surfaces.

The SiC varistor 5 has a small relative dielectric constant of S
A counter electrode 7 is formed on the upper and lower surfaces of a varistor sintered body 6 having iC (relative permittivity: 10 to 30) as a main component, and a region excluding both end surfaces thereof is covered with a glass coating 8. I have. The varistor sintered body 6 is formed by adding an organic binder to a raw material obtained by adding a glass material to SiC powder, forming the material into a square plate shape, and then firing. The counter electrode 7 is formed on the upper and lower surfaces of the varistor sintered body 6 by a method such as printing, baking, vapor deposition, sputtering, or the like. More specifically, as shown in FIG.
Is formed from a position that does not reach one end face of the varistor sintered body 6 to the other end face and is exposed to the other end face of the SiC varistor 5. The other counter electrode 7 is connected to the other end of the varistor sintered body 6. It is formed from a position that does not reach the end face to one end face and is exposed at one end face of the SiC varistor 5. The electrode material of the counter electrode 7 is not particularly limited as long as it is a metal material having good conductivity such as Ag, Ag / Pd, and Pt.

Here, the varistor voltage of the SiC varistor 5 can be arbitrarily set according to the thickness between the upper and lower surfaces of the varistor sintered body 6. Further, the capacitance of the SiC varistor 5 can be arbitrarily adjusted depending on the overlapping area between the counter electrodes 7.

The capacitor 1 has a counter electrode 3 formed on the upper and lower surfaces of a capacitor sintered body 2, and a region excluding both end surfaces thereof is covered with a glass coating 4.
The capacitor sintered body 2 is formed by adding an organic binder to a known capacitor material such as a porcelain material such as BaTiO ₃ to form a square plate, followed by firing. The counter electrode 3 is formed on both the upper and lower surfaces of the capacitor sintered body 2 by a method such as printing and baking, vapor deposition, or sputtering. Specifically, as shown in FIG.
One counter electrode 3 is formed from a position that does not reach one end face of the capacitor sintered body 2 to the other end face and is exposed to the other end face of the capacitor 1.
It is formed from a position that does not reach the other end face of the capacitor sintered body 2 to one end face and is exposed on one end face of the capacitor 1. The electrode material of the counter electrode 3 is Ag, Ag / P
Any metal material having good conductivity such as d and Pt may be used, and is not particularly limited. The capacitance of the capacitor 1 is adjusted by the thickness (element thickness) between the upper and lower surfaces of the capacitor sintered body 2, the overlapping area of the counter electrodes 3, the capacitor material used for the capacitor sintered body 2, and its composition. Can be.

The element body 9 is formed by laminating the capacitor 1 covered with the glass film 4 and the SiC varistor 5 covered with the glass film 8 with an adhesive and laminating and integrating them. External electrodes 10 made of metal caps are respectively attached to both end surfaces of the element body 9, and the external electrodes 10 are fixed to the element body 9 with high-temperature solder. At this time, the external electrode 10 and the respective counter electrodes 3 and 7 are simultaneously electrically connected, and the capacitor 1 and the SiC varistor 5 are connected in parallel through the external electrode 10.

As the adhesive for bonding the capacitor 1 and the SiC varistor 5, the same glass as the glass coatings 4 and 8 may be used, or the glass coatings 4 and 8 may be remelted and bonded. . In the first embodiment, the capacitor 1 and the SiC varistor 5 are bonded to each other with both surfaces covered with the glass coatings 4 and 8, but instead of this, the capacitor 1 and the SiC varistor 5 are bonded together.
After one surface of each of the C varistors 5 is covered with the glass coatings 4 and 8, the surfaces not covered with the glass can be bonded with glass.

S used in the chip type electronic component of the present invention
Since the response speed of the iC varistor 5 is faster than that of the ZnO varistor, even if the capacitance of the capacitor 1 connected in parallel with the SiC varistor 5 is reduced, it is possible to obtain a surge countermeasure component having no response delay against high-speed noise. it can. further,
Since the SiC varistor 5 mainly composed of SiC having a small relative dielectric constant is used, the capacitance of the varistor portion can be reduced. Therefore, the total capacitance (combined capacitance) of the SiC varistor 5 and the capacitor 1 can be reduced, and this chip-type electronic component can be used as a surge suppression component that can also handle high-speed signal lines.

In particular, if the total capacitance of the SiC varistor 5 and the capacitor 1 is set to 100 pF or less, it is possible to obtain an excellent surge countermeasure component. In a chip-type electronic component using a conventionally used ZnO varistor, the total capacitance was larger than 100 pF and could not be reduced to 100 pF or less.
A chip-type electronic component using a C varistor can have a total capacitance of 100 pF or less, and can be used as a surge suppression component suitable for high-speed signal lines.

In this chip type electronic component,
Since the areas exposed from the external electrodes 10 of the capacitor 1 and the SiC varistor 5 are covered with the glass coatings 4 and 8, the capacitor 1 and the SiC varistor 5 can be protected from chemicals, corrosive gas and the like.

Further, in this chip type electronic component, since the capacitor 1 and the SiC varistor 5 are adhered by an adhesive, the capacitor 1 and the SiC varistor 5 are laminated and fired on the element body 9 as in the case of simultaneous firing. There is no risk of warpage or distortion occurring. Further, after selecting the capacitor 1 having predetermined characteristics and the SiC varistor 5, they can be integrated by bonding with an adhesive. As a result, the reject rate can be reduced.

(Second Embodiment) FIG. 4 is a sectional view showing the structure of a chip-type electronic component according to another embodiment of the present invention. The chip-type electronic component is formed by firing a laminate in which the SiC varistor sheet 17 and the capacitor sheet 13 are pressed, thereby forming the SiC varistor 15 and the capacitor 1.
1 are laminated and integrated. Hereinafter, the structure of the chip-type electronic component will be described with reference to FIGS.

First, an organic binder is added to a raw material obtained by adding glass to SiC powder, and the mixture is kneaded well to form a slurry, and a green sheet having a thickness of several μm to several hundred μm is obtained by a doctor blade method. Similarly, for example, BaTi
After adding an organic binder to a capacitor material such as a porcelain material such as O ₃ and kneading the mixture well to form a slurry, a green sheet having a thickness of several μm to several hundred μm is obtained by a doctor blade method. Next, each green sheet is cut into a predetermined size to obtain a SiC varistor sheet 17 and a capacitor sheet 13. On the upper surface of the SiC varistor sheet 17, a conductive paste is printed in a pattern as shown in FIG. Also, on the upper surface of the capacitor sheet 13, a conductive paste is printed in a pattern as shown in FIG. 6 to form the internal electrodes 14. Ag, Pd, Ag / Pd, P
t, Ni, etc. are used.

Thereafter, as shown in FIG.
A predetermined number of capacitor sheets 1 in which internal electrodes 14 are formed on capacitor sheets 13 on which no
3 are laminated, and a capacitor sheet 13 on which the internal electrodes 14 are not formed is laminated thereon, thereby forming the capacitor 11. Here, the capacitor sheets 13 having the internal electrodes 14 are overlapped so that the directions of the internal electrodes 14 are alternately reversed, and the internal electrodes 14 of each layer are alternately exposed on both end surfaces of the capacitor 11.

Furthermore, the SiC varistor sheet 1 on which the internal electrodes 18 are not formed is formed on the capacitor 11.
7, a predetermined number of SiC varistor sheets 17 each having an internal electrode 18 formed thereon are laminated, and an SiC varistor sheet 17 having no internal electrodes 18 formed thereon is laminated thereon. 15. Here, the SiC varistor sheet 17 having the internal electrodes 18 is overlapped so that the directions of the internal electrodes 18 are alternately reversed, and the internal electrodes 18 of the respective layers are
Alternately exposed at both end faces.

Next, the capacitor sheet 13 and the SiC
The laminated body to which the varistor sheet 17 is pressed is fired at a predetermined temperature to obtain a sintered body of the element body 19. Then, a conductive paste is applied to both end surfaces of the element body 19 where the internal electrodes 14 and 18 are exposed, and the paste is fired to form the external electrodes 20. Ag, P is used as the conductive paste material for the external electrode.
d, Ag / Pd, Ag / Pt, etc.
A plating process is performed using i, Sn, or the like.

The order of stacking the sheets is as follows.
As shown in FIG. 7, the capacitor sheet 13 may be laminated, and the SiC varistor sheet 17 may be laminated thereon. However, the SiC varistor sheet 17 is laminated, and the capacitor sheet 13 is laminated thereon. Order.

In this embodiment, since the SiC varistor 15 and the capacitor 11 are stacked and fired, only one firing step is required to obtain a fired body of the element body 19, and the manufacturing process is simplified. Is done. However, if the difference between the heat shrinkage of the material of the SiC varistor sheet 17 and the heat shrinkage of the material of the capacitor sheet 13 is large, the element body 19 may be distorted or warped in the firing step. Thermal expansion coefficient of material of sheet 13 and SiC
It is desirable that the materials of the varistor sheets 17 have substantially the same heat shrinkage.

Further, the interface between the SiC varistor 15 and the capacitor 11 is
The intermediate layer (not shown) may be formed of an insulating material having an intermediate heat shrinkage ratio, for example, a material obtained by mixing a material for a SiC varistor and a material for a capacitor, so as to relax the distortion.

The capacitors 11 are stacked on the upper and lower sides of the SiC varistor 15 (or vice versa).
1 may be sandwiched). If the sandwich structure is vertically symmetric, warpage is less likely to occur during firing of the element body 19.

Also in this chip-type electronic component, the capacitance of the varistor portion can be reduced because the SiC varistor 15 having a high response speed is mainly composed of SiC having a small relative dielectric constant as a main component. The capacitance of the connected capacitor 11 can also be reduced. Therefore, the total capacitance of the SiC varistor 15 and the capacitor 11 can be reduced, and it can be used as a surge suppression component that can be used for high-speed signal lines.

In particular, the SiC varistor 15 and the capacitor 1
If the total capacitance of 1 is set to 100 pF or less, an excellent surge countermeasure component can be obtained. In a chip-type electronic component using a conventionally used ZnO varistor, the total capacitance is larger than 100 pF and cannot be reduced to 100 pF or less.
A chip-type electronic component using an iC varistor can have a total capacitance of 100 pF or less and can be used as a surge suppression component suitable for a high-speed signal line.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a chip-type electronic component according to an embodiment of the present invention.

FIG. 2 shows a Si used in the chip-type electronic component of FIG.
It is a perspective view which shows the structure of C varistor.

FIG. 3 is a perspective view showing a structure of a capacitor used in the chip-type electronic component of FIG.

FIG. 4 is a cross-sectional view illustrating a structure of a chip-type electronic component according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a SiC varistor sheet on which internal electrodes are formed, which is used for the chip-type electronic component of FIG. 4;

FIG. 6 is a perspective view showing a capacitor sheet on which internal electrodes are formed, which is used for the chip-type electronic component of FIG. 4;

FIG. 7 is a perspective view showing a stacking order of a sheet for a SiC varistor and a sheet for a capacitor in FIG. 4;

FIG. 8 is a sectional view showing the structure of a conventional chip-type electronic component.

FIG. 9 is an equivalent circuit diagram of the chip-type electronic component of FIG.

[Explanation of symbols]

 Reference Signs List 1 capacitor 2 capacitor sintered body 3, 7 counter electrode 5 SiC varistor 6 varistor sintered body 10 external electrode 11 capacitor 13 capacitor sheet 14, 18 internal electrode 17 SiC varistor sheet 20 external electrode

Continued on the front page (72) Inventor Takashi Kama 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (Reference) 5E001 AB03 AE02 AE03 AF03 AF06 AH01 AH03 AJ03 5E034 CA07 CB01 CC14 DA02 DA07 DC01 DD04 DE07 5E082 AA01 AB03 BB10 BC10 DD04 EE04 EE05 EE11 EE23 EE35 EE37 FF05 FG06 FG26 FG46 GG10 HH43 PP01

Claims (5)

[Claims] 1. A chip-type electronic component in which a varistor and a capacitor are connected in parallel and integrated, wherein the varistor constituting the varistor is made of a low dielectric constant material containing SiC as a main component. parts. 2. The chip-type electronic component according to claim 1, wherein the varistor material has a relative dielectric constant of 10 or more and 30 or less. 3. The combined capacitance of the varistor and the capacitor is 100 pF or less.
Alternatively, the chip-type electronic component according to claim 2. 4. The chip-type electronic component according to claim 1, wherein said varistor and said capacitor are laminated and integrated by simultaneous firing. 5. The chip-type electronic component according to claim 1, wherein the fired varistor and the fired capacitor are integrated by bonding.