JPH06140277A - Laminated ceramic capacitor - Google Patents

Abstract

PURPOSE:To provide a laminated ceramic capacitor excellent in reliability by a method wherein inner electrodes are securely joined to an outer electrode, and a capacitiver element is enhanced in adhesive strength to the outer electrode. CONSTITUTION:An inner electrode 5 is screen-printed on a green sheet 4, wherein the pattern of the inner electrode 5 is formed so as to make an outer electrode 3 outlet meet a formula, theta<=90 deg., concretely either theta<=45 deg. or theta=90 deg. at a corner. 50 pieces of green sheet blanked out 20mum thick are laminated to form a laminated ceramic capacitor, wherein a joint between the outer electrode 3 and the inner electrodes 5 is enlarged in area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated ceramic capacitor, and more particularly to the structure of internal electrodes.

[0002]

2. Description of the Related Art Conventionally, multilayer ceramic capacitors (hereinafter referred to as capacitors) are used in a wide range of fields due to their excellent characteristics such as small size and large capacity, semi-permanent life and low resistance at high frequencies. It is often used as a power source for exchanges. In the manufacturing method, a dielectric ceramic powder is made into a slurry using an organic binder and an organic solvent, and then, as shown in FIG. 2, a green sheet 1 having a constant thickness is formed by a doctor blade method or the like. Gold (Au), Valladium (Pd), Silver (A
g), copper (Cu), nickel (Ni) or other low resistance metal dispersed in an organic vehicle, a paste containing metal powder, a screen to obtain an outlet for alternately connecting to an external electrode in a certain shape A green chip of a monolithic ceramic capacitor is obtained by printing, punching out the green sheet, and stacking so as to form a parallel structure of capacitors when forming external electrodes later. Then, binder removal is performed, firing is performed, an external electrode connected to the internal electrode is applied, and firing is performed to obtain a capacitor element. FIG. 2 shows a cross-sectional view of a conventional monolithic ceramic capacitor and an internal electrode pattern. The external electrode 3 is connected to the internal electrode 2, and the glass component in the external electrode paste diffuses to the external electrode extraction portion of the internal electrode 2 to enhance the adhesion strength. 3, the area of the external electrode extraction portion of the internal electrode is insufficient, the internal electrode 2 and the external electrode 3 are broken or the equivalent series resistance is increased due to a defective connection, and the electrostatic capacitance is increased. There was a problem in terms of reliability, which caused defects such as shortages.

[0003]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention secures the joint portion between the external electrode and the internal electrode and improves the adhesion strength between the external electrode and the capacitor element. Therefore, it is to provide a multilayer ceramic capacitor having excellent reliability.

[0004]

According to the present invention, the internal electrode pattern of the external electrode lead-out portion of the monolithic ceramic capacitor is widened to the surrounding portion after the external electrode dip on the side surface. It is characterized in that there are many electrode connection parts. That is, the present invention provides a multilayer ceramic capacitor in which ferroelectric ceramic layers and internal electrode layers made of low-resistance metal are alternately laminated, and the internal electrodes are connected to different external electrodes every other one. The internal electrode of the lead-out portion is made wider than the width of the effective internal electrode layer, and the extension of the lead-out portion in that case is 90 ° or less with respect to the internal electrode. The monolithic ceramic capacitor is characterized in that its portion is enlarged.

[0005]

The internal electrode of the monolithic ceramic capacitor according to the present invention has a large area for the external electrode outlet to the margin portion and the corner portion, thereby increasing the connecting portion between the internal electrode and the external electrode. The connection between the internal electrode and the internal electrode becomes firm, and the connection between the external electrode and the internal electrode is reliably ensured even when the electrode is shrunk. Further, since the glass component in the external electrode paste diffuses more widely inside the capacitor element toward the internal electrode, it is possible to obtain a highly reliable multilayer ceramic capacitor with improved adhesion strength between the external electrode and the capacitor element.

[0006]

EXAMPLES Example 1 FIG. 1 is an explanatory view of a printed pattern of internal electrodes of a laminated ceramic capacitor of the present invention. 1A is an exploded perspective view, FIG. 1B is a perspective view showing the shape of the external electrode of the multilayer ceramic capacitor of the present invention, and FIG. 1C is a side view of the internal electrode of the print pattern. FIG. 7 is a plan view showing an angle θ of expansion of a taken-out portion.
The present invention is characterized in that the external electrode take-out portion is widely provided in order to compensate for insufficient adhesion strength between the external electrode and the capacitor element of the conventional multilayer ceramic capacitor.
In this example, powder having a lead (Pb) -based perovskite structure and a particle size of 1 micron or less was used as the ferroelectric ceramics as a base material of the capacitor, and silver (Ag) and palladium ( An alloy powder having a Pd ratio of 70:30 was used. Dielectric ceramic powder 100wt%
After preparing a slurry consisting of 4 wt% of organic binder and 40 wt% of organic solvent, a green sheet 4 having a thickness of 20 μm is prepared by a doctor blade method, and the internal electrode 5 pattern according to the present invention is screen-printed on the green sheet 4. did. In this case, the pattern of the internal electrode 5 was drawn within a range of θ ≦ 90 ° after sintering from the corner portion having the outlet of the external electrode 3 at that position. Specifically, the ceramic end face was extended at an angle of θ = 45 °. As a protective layer, a 20-micron green sheet is punched out and laminated in a mold to 300 microns, and then 50 layers are laminated so that they can be taken out alternately to the external electrode 3 that opposes the green sheet on which the above-mentioned internal electrode 5 is printed. As a layer, a 300-micron green sheet laminate was performed, hot pressing and pressure bonding were performed at 100 to 120 ° C. for 1 hr, and a peak binder was treated at 450 ° C. for 4 days to remove the binder.
Firing was performed at 950 ° C. for 10 to 15 hours. After that, A
An external electrode paste containing 100% grit glass frit was applied to the external electrode outlet and baked to obtain a monolithic ceramic capacitor according to an example of the present invention. 100 monolithic ceramic capacitors according to this embodiment and 100 conventional monolithic ceramic capacitors with external electrode outlets.
Equivalent series resistance (ESR) and adhesion strength with the external electrode 3 were measured. Table 1 shows the structure of the external electrode outlet, the ESR, and the evaluation results of the adhesion strength in comparison with the conventional structure (θ = 0 °).

[Table 1]

[0007] An impedance analyzer is used to measure the ESR, and 10 m of cream solder is applied to the base to measure the adhesion strength.
g printing was performed, the sample was soldered using a reflow oven, a hole was previously formed in the substrate under the sample, and measurement was performed from below through the hole using a pressure gauge.

[Embodiment 2] A capacitor having a pattern corner angle θ = 90 ° was prepared by the same method as in Embodiment 1, the same evaluation was performed, and the results are summarized in Table 1.

[0009]

The multilayer ceramic capacitor according to the present invention is improved in ESR by forming the external electrode outlet portion of the internal electrode wide, and at the same time, the adhesion strength between the external electrode and the capacitor element is the same as that of the conventional internal capacitor. This is an improved and more reliable multilayer ceramic capacitor than the structure of the internal outlet of the electrode.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a printed pattern of internal electrodes of a monolithic ceramic capacitor according to the present invention. 1A is an exploded perspective view, and FIG. 1B is a perspective view showing the shape of external electrodes of the monolithic ceramic capacitor of the present invention. FIG. 1C is a plan view showing the angle θ of the print pattern.

2A and 2B are explanatory views showing a conventional monolithic ceramic capacitor, FIG. 2A is an exploded perspective view, and FIG. 2B is a perspective view showing formation of external electrodes of the conventional monolithic ceramic capacitor.

[Explanation of symbols]

 1 Green Sheet 2 (Conventional) Internal Electrode 3 External Electrode 4 Green Sheet 5 (Inventive) Internal Electrode

Claims (1)

[Claims] 1. A multilayer ceramic capacitor in which ferroelectric ceramic layers and internal electrode layers made of low-resistance metal are alternately laminated, and every other internal electrode layer is connected to a different external electrode. The internal electrode at the extraction port is made wider than the width of the effective internal electrode layer, and the expansion of the extraction part in that case is formed by forming the extraction part at 90 ° or less (excluding 0 °) with respect to the side surface of the internal electrode. A multi-layer ceramic capacitor having a large connection between the external electrode and the internal electrode.