JPH0613260A - Multilayered ceramic porcelain element - Google Patents

Abstract

PURPOSE:To eliminate and suppress high frequency noise in a signal line, and improve humidity resistance, by using a multilayered ceramic porcelain element to protect a semiconductor element such as an IC and an LSI, an electronic machine, and the circuit of an electronic machine, from abnormal high voltage such as noise, pulse and static electricity generated by an electronic machine. CONSTITUTION:Ceramic layeres 1a, 1b, 2 and inner electrode layers 3a, 3b are alternately laminated. The total thickness of ceramic layers of the uppermost layer 1a and the lowermost layer 1b of a laminated ceramic porcelain element of one layer is constituted to be larger than the thickness of the ceramic layer 2 sandwiched by the inner electrode layers 3a, 3b. By changing the shapes of the inner electrodes 3a, 3b, the capacitance is reduced. Thus high frequency noise is eliminated, and the amount of energy which can be absorbed can be adjusted. Further by forming a dense coating film on the surface or the inside of the element, humidity characteristics can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention protects semiconductor elements such as ICs and LSIs and circuits of electronic devices and electric devices from abnormal high voltage such as noise, pulse and static electricity generated in electronic devices and electric devices and high frequency noise. The present invention relates to a laminated ceramic porcelain element used for the purpose.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as ICs and LSIs have been widely used for electronic devices and electric devices in order to realize miniaturization and multifunctional functions. The withstand voltage against abnormally high voltage is low. Therefore, film capacitors, electrolytic capacitors, semiconductor ceramic capacitors, monolithic ceramic capacitors, etc. are used to secure the resistance to abnormally high voltage such as noise, pulse, and static electricity of these electronic devices and electric devices. Although it exhibits excellent characteristics for absorbing and suppressing relatively low noise and high frequency noise, it does not show its effect for high voltage pulses and static electricity, and may cause malfunction or destruction of semiconductor elements.

Further, SiC and ZnO type varistors are used for absorbing and suppressing high voltage pulses and static electricity, but these are effective for absorbing and suppressing noise with relatively low voltage and high frequency noise. However, it may cause a malfunction of the semiconductor device, and as a complement to these two defects, JP-A-57-27001 and JP-A-57-57
SrTiO ₃ as disclosed in Japanese Patent No. 35303
Varistors have been developed and are in use.

On the other hand, in the field of electronic components, development of chip components which can be surface-mounted has become indispensable due to further progress in lightness, thinness, shortness and high performance in response to the miniaturization of equipment. Corresponding to these, examples in which the contents disclosed in JP-A-54-53248 and JP-A-54-53250 are applied, JP-A-59-215701,
There is an example disclosed in Japanese Patent Laid-Open No. 63-219115, but these methods are still in practical use because they are complicated in process and the obtained characteristics are insufficient for achieving the purpose. Has not reached the stage. Therefore, the inventors of the present invention disclosed in Japanese Patent Application No. 1-86243 a method that can be put to practical use by a new composition and a new manufacturing method.

[0005]

[Problems to be Solved by the Invention] Conventionally, laminated SrTi
As for the O ₃ -based varistor, various material compositions and manufacturing methods have been developed as shown in the above-mentioned conventional example, but in any case, it is not reached the level of practical use due to the complicated process. I had a problem. Also, the characteristics of the obtained device show its effect in absorbing and suppressing high voltage pulses and static electricity applied to the power supply line, but not in absorbing and suppressing high frequency noise applied to the signal line. Had a point.

The present invention solves the above-mentioned conventional problems and is capable of absorbing and suppressing high-frequency noise applied to a signal line, and does not break even when an abnormal voltage such as an electrostatic pulse is applied.
It is an object of the present invention to obtain a laminated ceramic porcelain element having excellent environment resistance characteristics, particularly moisture resistance.

[0007]

The laminated ceramic porcelain element of the present invention is provided with two internal electrode layers such that ceramic layers and internal electrode layers are alternately laminated, and each of the two internal electrode layers is provided. An object of the present invention is to solve the above-mentioned problems by connecting one end to an opposing external electrode and making the total thickness of the uppermost and lowermost ceramic layers larger than the thickness of the ceramic layers sandwiched by the internal electrode layers. Is.

[0008]

According to this structure, since the ceramic layers and the internal electrode layers of the laminated ceramic porcelain element are alternately laminated and only one ceramic layer is sandwiched between the internal electrode layers, the distance between the electrodes can be increased and the capacitance can be increased. Can be made smaller. The total thickness of the uppermost and lowermost ceramic layers of the multilayer ceramic porcelain element is made larger than the thickness of the ceramic layers sandwiched by the internal electrode layers, so that the voltage applied across the electrodes is sandwiched by the internal electrode layers. The laminated ceramic porcelain element can be made to function without leaking to the surface of the laminated ceramic porcelain element in addition to the ceramic layer.

Further, the effective electrode area can be changed according to the purpose of use by variously changing the shape of the internal electrode layer, and the electrostatic capacitance can be reduced by increasing the distance between the electrodes and decreasing the effective electrode area. You can

As a result, it is possible to increase the resonance frequency at which the noise attenuation rate is maximized as the electrostatic capacitance becomes smaller, and it is possible to absorb and suppress the high frequency noise riding on the signal line. Further, by varying the shape of the effective electrode surface, the amount of noise energy that can be absorbed can be adjusted without changing the electrostatic capacitance.

Further, the main component of the ceramic layer is SrTi.
O ₃ or part of Sr of the SrTiO ₃ is replaced with Ca, Mg,
By using a material in which at least one element of Ba is substituted, both characteristics of the capacitor and the varistor can be provided. This prevents the element from being destroyed even when an abnormally high voltage such as an electrostatic pulse having a sharp rise is applied.

Further, a coating film may be formed on the surface, inside or both of the thus-produced multilayer ceramic porcelain element with a coating agent whose main component is at least one of Si, Al and Ti. As a result, a uniform and dense coating film can be obtained, so that the environment resistance characteristics, especially the humidity resistance characteristics can be remarkably improved.

[0013]

Embodiments (Embodiment 1) Hereinafter, embodiments will be specifically described.

First, SrCO is used as the first component.₃, CaC
O₃, TiO₂(Sr_0.98Ca_0.02)_0.995TiO₃Set of
99.2 mol% as a composition ratio, as the second component
Nb ₂O_Five0.3 mol% and MnCO as the third component₃To
0.2 mol%, Cr₂O₃0.1 mol% as the fourth component
SiO₂0.2 mol% is weighed and measured by a ball mill or the like.
20Hr mixed, crushed and dried, then 800 ℃ in air
Calcination for 2 hours with 80Hr mixing again with a ball mill etc.
If so, pulverize so that the average particle size is 1.0 μm or less.
It The powder thus obtained may contain butyral resin, etc.
Machine binder and organic solvent are mixed to form a slurry,
Thickness of 50 by sheet forming method such as K.Blade method
A green sheet 1 of about μm is obtained.

Next, a predetermined number of the sheets 1 are laminated to form the bottom invalid layer 1b shown in FIGS. 1 and 2.
The inner electrode 3a, which is made of Pd or the like and has a rectangular shape, is printed and dried by screen printing or the like, and a predetermined number of the sheets 1 are stacked on the inner electrode 3a. The inner electrode 3b in the shape of a triangle whose base is a portion connected to the outer electrode 4.
Is printed by screen printing and dried. that time,
The internal electrodes 3a and 3b are printed so as to face each other and reach different edges. Finally, a predetermined number of the sheets 1 are laminated to form the uppermost ineffective layer 1a, and pressure is applied while heating,
Crimping and cutting into a predetermined shape.

[0016] Next, degreasing calcining is performed in air at 800 ° C for 20 hours, and for example 121 in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After baking for 10 hours at 0 ° C, 2 hours at 930 ° C in air
Reoxidize. After that, an external electrode paste made of Ag or the like is applied to both end surfaces of the internal electrodes 3a and 3b exposed at different edges, and the paste is baked in air at 700 ° C. for 10 minutes. Next, the external electrode 4 is formed on the external electrode by electroplating, for example, Ni plating and solder plating.

The initial characteristics and reliability test results of the thus-obtained monolithic ceramic porcelain element are shown in Table 1. 1 and 2 are views showing the laminated structure of the sheets of this embodiment. In FIG. 1, 1 is a sheet, 3 is an internal electrode, and 4 is an external electrode.

[0018]

[Table 1]

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIGS.

The internal electrode layer 3 was formed in the same manner as in Example 1.
A monolithic ceramic porcelain element was obtained in which a and 3c had a substantially rectangular shape in which one electrode had a rectangular shape and the other electrode had a base portion where the other electrode was connected to the external electrode and the other two sides had a curved curve inward. After that, an organic-based resist is applied to the external electrodes 4 and then dried, and the laminated ceramic porcelain element is dipped in a coating agent composed of an alkoxide solution containing Si as a main component, pre-dried at 100 ° C., and then toluene or the like. The above resist is dissolved and removed by immersing in the organic solvent, etc., and then baked at 450 ° C. for 20 minutes to form the coatings 5a and 5b.
To form. Next, N is formed on the external electrode by, for example, an electrolytic method.
i plating and solder plating are applied.

The results of the initial characteristics and reliability test of the thus-obtained monolithic ceramic porcelain element are shown in Table 2. 3 and 4 are sectional views of the laminated ceramic porcelain element of this embodiment. In FIG. 3, 5a and 5b are coating films formed by a coating agent.

[0022]

[Table 2]

In this example, the composition of the ceramic powder is shown only for some combinations, but SrT
Any composition may be used as long as it has a function of both a capacitor and a varistor and has iO ₃ as a main component. Further, the ineffective layers 1a and 1b and the effective layer 2 are formed by laminating thin sheets 1, but one thick sheet may be formed.

Further, the internal electrodes 3a, 3 shown in this embodiment are
b, 3c and the external electrode 4 may be not only a noble metal such as Pd or Ag but also a non-metal or non-metal oxide such as Cu, Ni or Cr, or a mixture thereof.

Regarding the electrical characteristics, the voltage applied across the element when a current of 0.1 mA flows through the monolithic ceramic porcelain element is represented by V _{0.1 mA} , and the capacitance and ta
nδ is a value measured at 1 kHz. Moreover, regarding the reliability test, 85 ° C., 85 RH%, charge rate 90%, 500
The change rate after time is shown. Here, the charge rate is a value obtained by dividing the voltage applied to the element by the initial V _{0.1 mA} of the element.

The shape of the laminated ceramic porcelain element shown in this embodiment is W3.20 mm × D1.60 mm × T2.0.
It is called a 1x3 type formed with a size of 0 mm.

[0027]

As described above, according to the present invention, since the ceramic layers and the internal electrode layers of the laminated ceramic porcelain element are alternately laminated and the ceramic layer sandwiched by the internal electrode layers is only one layer, the inter-electrode The distance can be increased and the capacitance can be decreased.

Further, by making the total thickness of the uppermost and lowermost ceramic layers of the monolithic ceramic porcelain element larger than the thickness of the ceramic layers sandwiched by the internal electrode layers, the voltage applied to both ends of the electrodes is increased. In addition to the ceramic layers sandwiched between the layers, the laminated ceramic ceramic element can be made to function without leaking the surface of the laminated ceramic ceramic element.

Further, the effective electrode area can be easily changed according to the purpose of use by variously changing the shape of the internal electrode layer, and the electrostatic capacitance is further increased by increasing the distance between the electrodes and decreasing the effective electrode area. Can be made smaller.

As a result, it is possible to increase the resonance frequency at which the noise attenuation rate is maximized as the electrostatic capacitance becomes smaller, and it is possible to absorb and suppress the high frequency noise riding on the signal line. Further, by varying the shape of the effective electrode surface, the amount of noise energy that can be absorbed can be adjusted without changing the electrostatic capacitance.

Further, the main component of the ceramic layer is SrTi.
O ₃ or part of Sr of the SrTiO ₃ is replaced with Ca, Mg,
By using a material in which at least one element of Ba is substituted, both characteristics of the capacitor and the varistor can be provided. As a result, the element will not be destroyed even if an abnormally high voltage such as an electrostatic pulse having a sharp rise is applied. Further, since the current density is increased by decreasing the effective electrode area, α can be increased, tan δ can be decreased to reduce the limiting voltage, and the surge resistance and energy resistance can be increased.

In addition, a film may be formed on the surface or inside or both of the thus-produced laminated ceramic porcelain element with a coating agent whose main component is at least one of Si, Al and Ti. As a result, a uniform and dense coating film can be obtained, so that the environment resistance characteristics, especially the humidity resistance characteristics can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a laminated ceramic porcelain element according to a first embodiment of the present invention.

FIG. 2 is a plan view of a laminated ceramic porcelain element showing the shape of internal electrodes in the same example.

FIG. 3 is a sectional view showing a structure of a laminated ceramic porcelain element according to a second embodiment of the present invention.

FIG. 4 is a plan view of a laminated ceramic porcelain element showing the shape of internal electrodes in the same example.

[Explanation of symbols]

 1 sheet 1a uppermost ineffective layer 1b lowermost ineffective layer 2 effective layers 3a, 3b internal electrode 5 coating formed by coating agent

Claims (12)

[Claims] 1. A two-layer internal electrode layer is provided so that ceramic layers and internal electrode layers are alternately laminated, and one end of each of the two internal electrode layers is connected to an opposing external electrode, and the uppermost layer is formed. A multilayer ceramic porcelain element configured such that the total thickness of the lowermost ceramic layers is larger than the thickness of the ceramic layers sandwiched by the internal electrode layers. 2. The internal electrode layer has a shape of a rectangle in which one electrode is connected to an external electrode at one end and a triangle whose base is a portion where the other electrode is connected to the external electrode facing the external electrode. The multilayer ceramic porcelain element according to claim 1. 3. The shape of the internal electrode layer is a rectangle in which one electrode is connected to an external electrode at one end, and the other electrode is connected to the external electrode opposite to the external electrode, with the base being the other portion. The laminated ceramic porcelain element according to claim 1, wherein the laminated ceramic porcelain element has a substantially triangular shape in which two sides are curved inward. 4. The shape of the internal electrode layer is such that one electrode has a rectangular shape with one end connected to an external electrode, and the other electrode has a base connected to the external electrode opposite to the external electrode. The laminated ceramic porcelain element according to claim 1, wherein the laminated ceramic porcelain element has a substantially triangular shape whose two sides are curved outwardly. 5. The multilayer ceramic porcelain element according to claim 1, wherein the shape of the internal electrode layer is a triangle whose base is a portion where both internal electrodes are connected to respective external electrodes facing each other. 6. The shape of the internal electrode layer is a substantially triangular shape in which a portion where both internal electrodes are connected to respective external electrodes facing each other is the base and the other two sides are curved curves inward. The laminated ceramic porcelain element described. 7. The shape of the internal electrode layer is a substantially triangular shape in which a portion where both internal electrodes are connected to respective external electrodes facing each other is the base and the other two sides are curved curves to the outside. The laminated ceramic porcelain element described. 8. The shape of the internal electrode layer is a triangle whose base is a part where one electrode is connected to the external electrode, and the other side is an internal part when the part where the other electrode is connected to the external electrode is the base. The monolithic ceramic porcelain element according to claim 1, wherein the monolithic ceramic porcelain element has a substantially triangular shape with a curved curve. 9. The shape of the internal electrode layer is a triangle whose base is a portion where one electrode is connected to an external electrode, and the other side is an external portion where the base is a portion where the other electrode is connected to the external electrode. The monolithic ceramic porcelain element according to claim 1, wherein the monolithic ceramic porcelain element has a substantially triangular shape with a curved curve. 10. The shape of the internal electrode layer is a substantially triangular shape having a curved line in which one electrode is connected to the external electrode at the base and the other two sides are curved inward, and the other electrode is connected to the external electrode. 2. The laminated ceramic porcelain element according to claim 1, wherein the formed portion is a base and the other two sides are substantially triangular with a curved line curved outward. 11. The main component of the ceramic layer is SrTiO ₃ or a part of Sr of this SrTiO ₃ is Ca, Mg, Ba.
3. A material obtained by substituting at least one of the above elements and having characteristics of both a capacitor and a varistor, claim 1, claim 2, claim 3, claim 4, claim 5, claim 5. The laminated ceramic porcelain element according to claim 6, claim 7, claim 8, claim 9, or claim 10. 12. The coating according to claim 1 or 11, wherein a coating is formed on the surface or inside of the ceramic layer, or both, with a coating agent whose main component is at least one of Si, Al and Ti. Multilayer ceramic porcelain element.