JP2003059786A - Method of manufacturing ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an electronic component of a high reliability by forming an external electrode of a high reliability, easily without generating bubble inclusion and dents. SOLUTION: A ceramic sintered body with an end face to be formed with an external electrode faced downwards is dipped at a speed A in a conductive paste stored in a predetermined depth in a paste bath, and then is stopped at a predetermined position. Then, the ceramic sintered body is drawn up at a speed B, and then at a speed C from a position where the height from the inner bottom face of the paste bath to the end face is at most 1.5 times the height from the inner bottom face of the paste bath to the liquid level. The external electrode thus coated is dried and baked to fabricate a multilayer ceramic capacitor. The dipping speed (speed A) and the first draw-up speed (speed B) are set to 0.5 mm/sec. or below, and the second draw-up speed (speed C) is set to 0.5 mm/sec. or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramic electronic component, and more particularly to a method of manufacturing an external electrode by immersing it in a conductive paste, applying it, and then drying and firing it.

[0002]

2. Description of the Related Art Conventionally, in order to form an external electrode on a ceramic electronic component, a method of immersing an end face of the electronic component forming the external electrode in a conductive paste, followed by drying and firing has been adopted. However, as disclosed in Japanese Unexamined Patent Publication No. 4-263414, there is a problem that a dent or a bubble is generated in the vicinity of the center of the terminal in the step of immersing the end face of the electronic component in this conductive paste and pulling it up. .

The cause of the occurrence of the dent and the bubble bit will be described with reference to FIG. FIG. 4 is a state diagram of the conductive paste and external electrodes in the step of immersing the electronic component in the conductive paste and pulling it up.

4A to 4D show the respective states of pulling up, and FIGS. 4E and 4F show the shapes of the external electrodes after pulling up.

In FIG. 4, 1 is an electronic component, 11 is an external electrode, 2 is a conductive paste, 3 is a paste tank filled with a conductive paste, 4 is a void, 5 is a recessed portion of the external electrode 11, and 6 is external. Bubbles in the electrode.

The end surface of the electronic component 1 on which the external electrode is to be formed is immersed in the bottom surface of the paste tank 3 filled with the conductive paste 2 (a). After soaking, electronic component 1 at a predetermined speed
The cavitation occurs in the area sandwiched between the electronic component 1 and the paste tank 3 at this time,
A void 4 is generated (b). Here, the electronic component 1 is placed in
When it is pulled up at a speed faster than the disappearance of the conductive paste 2, the conductive paste 2 is lifted with the void 4 still inside (c). If the pulling is continued at the same speed in this state, the void 4 becomes completely higher than the liquid surface of the conductive paste 2 and the conductive paste cannot be pulled down in a sufficient amount to form the external electrode ( d).

When the pulling speed is made faster than the speed at which the void 4 disappears, as shown in (e) and (f),
A dent 5 is formed in the central portion of the external electrode 11, or a bubble 6 is included in the central portion of the external electrode 11. These dents 5 and internal bubbles 6 cause the reliability of the electronic component to be reduced.

On the other hand, as a method of eliminating the voids generated during the pulling process, it is conceivable to slow down the pulling speed.

A state showing an external electrode forming step when the pulling rate is slowed is shown in FIGS.

In FIG. 5, 1 is an electronic component, 11 is an external electrode, 2 is a conductive paste, 3 is a paste tank filled with a conductive paste, and 4 is a void.

As shown in FIG. 5, by slowing the pulling rate, the void 4 is not generated between the paste tank 3 and the electronic component 1 (a) → (b). However, when pulling up in this state, the conductive paste 2 attached to the electronic component 1 flows downward. In particular, the conductive paste 2 on the surface perpendicular to the end surface forming the external electrode of the electronic component 1 is taken away (c) → (d). As a result, the external electrode 11 has a very thin thickness, which naturally lowers the reliability.

Further, since the pulling speed is slowed down, the lead time of the product becomes long and the productivity is lowered.

An invention which solves such a problem is
JP-A-3-248410, JP-A-4-263414,
JP-A-4-263409, JP-A-4-26341
No. 0, disclosed in JP-A-4-275512.

The invention of (1) shows a method of applying an external electrode to a uniform thickness by attaching a mesh to a bottom plate of a paste tank and immersing an electronic component in a conductive paste filled in the paste tank. .

In the invention of (1), the electronic component is immersed in the conductive paste in the paste tank, and is moved in the lateral direction relative to the paste tank so that the electronic component and the inner bottom surface of the paste tank are separated from each other. It shows a method of removing bubbles generated during the process.

The invention of (1) shows a method of preventing the generation of bubbles by applying the conductive paste to the end surface of the electronic component with a roller in advance and then immersing it in the conductive paste filled in the paste tank. ing.

The invention of (1) suppresses cavitation that occurs between the paste tank and the end surface when immersed in the conductive paste by curving the end surface on which the external electrode of the electronic component is to be formed into a convex shape, A method for suppressing the generation of bubbles is shown.

The invention of (1) shows a method of suppressing cavitation at the time of pulling up and suppressing generation of bubbles by roughening the surface shape of the inner bottom surface of the paste tank.

[0019]

However, these conventional methods of forming external electrodes have problems to be solved.

In the invention, the inner bottom surface is roughened by attaching the mesh to the inner bottom surface of the paste tank.
However, in the process of replenishing the conductive paste in the paste tank and stretching it uniformly, bubbles are generated in the roughened portion. Since the end face of the electronic component is dipped in the conductive paste containing bubbles, there is a possibility that bubbles will be contained in the conductive paste which will be the external electrodes.

In the invention of (1), even if the electronic component is laterally moved in the conductive paste, the remaining bubbles may be agitated and increase, and eventually the probability of bubble entrapment may increase.

In the present invention, even when the roller is coated with the conductive paste on the end surface of the electronic component so as to make the wetting uniform during immersion, cavitation may occur at the moment when the roller separates from the end surface of the electronic component. There is a nature.

In the invention of (1), it is impossible to standardize the parts design by changing the shape of the end surface of the electronic parts. Further, since the central portion of the end face is curved so as to be raised, when the electronic component is mounted on a substrate or the like, it may be difficult to form a solder fillet.

In the invention of, the same as the invention of,
Secondary roughening may occur due to roughening the end faces.

Further, in each of the above-mentioned inventions, from the construction method,
The structure of the equipment is complicated and the cost is increased.

An object of the present invention is to easily form a highly reliable external electrode without producing bubbles and dents, and to manufacture an electronic component having high reliability.

[0027]

SUMMARY OF THE INVENTION According to the present invention, the rate of immersion in the conductive paste stored in the paste tank on the end face of the component is 0.5 mm or less per second, and when the end face of the component is pulled up, The height of the component end surface is 1.5 from the bottom of the paste tank to the liquid level of the conductive paste.
When the end face of the component is within the double range, the pulling speed of the component is 0.5 mm / sec or less, and when the height exceeds 1.5 times, the pulling speed of the component is 0.5 mm / sec or more and the external electrode is Form and manufacture ceramic electronic components.

Further, according to the present invention, the speed of immersion in the conductive paste stored in the paste tank on the end face of the component is set to 0.
When the component end surface is pulled up, the height of the component end surface from the bottom surface of the paste tank is within 1.5 times the height from the bottom surface of the paste tank to the liquid surface of the conductive paste. At a certain time, the pulling is temporarily stopped for a certain period of time, and the pulling speed after the stop is 0.5 mm / sec.
As described above, the external electrodes are applied to manufacture the ceramic electronic component.

Further, according to the present invention, the external electrode is formed by dipping and pulling up the conductive paste on the end face of the component a plurality of times, and the final dipping and pulling method of this series is performed by using the external electrode forming method described above. Manufactures ceramic electronic components.

[0030]

DETAILED DESCRIPTION OF THE INVENTION A method of manufacturing a monolithic ceramic capacitor according to a first embodiment will be described with reference to FIG.

The multilayer ceramic capacitor shown in this embodiment is manufactured through the following steps before the external electrode forming step.

First, an internal electrode made of a conductor such as Ni is screen-printed with a conductive paste on a ceramic green sheet made of a thin dielectric material. The ceramic green sheets having the internal electrodes are punched into a desired shape and laminated. The laminated body is compressed, cut, and fired to form a ceramic sintered body.
The ceramic sintered body is subjected to a pretreatment (chamfering) with a wet barrel or the like.

FIG. 1 (a) is a diagram showing the relationship between the end face position of the monolithic ceramic capacitor and time in the process of immersing the monolithic ceramic capacitor in a conductive paste bath and pulling it up, and FIG. 1 (b) is a diagram. It is the figure which showed the list of the speed conditions.

The ceramic sintered body, with its end surface facing downward, is immersed in a conductive paste provided in a paste tank at a predetermined depth at a speed A and temporarily stopped at a predetermined position. After that, pulling up at a speed B, 10 from the inner bottom surface of the paste tank.
It is pulled up at a speed C from a position separated by 0 μm. The external electrode thus coated is dried and fired to manufacture a monolithic ceramic capacitor.

Here, as shown in FIG. 1 (b), the speed A, the speed B, and the speed C were respectively shaken, and an external electrode was formed under the combined conditions, and an experiment was conducted on the occurrence of bubble entrapment and denting. The results are shown in Table 1.

Conditions 1 to 18 in Table 1 correspond to conditions 1 to 18 shown in FIG. Further, the folded thickness in Table 1 indicates the thickness of the external electrode formed on the surface perpendicular to the end surface on which the external electrode is to be formed.

[0037]

[Table 1]

As shown in Table 1, when the speed A and the speed B are each 0.5 mm or less per second, bubble entrapment does not occur.

Further, when the external electrode is formed under the condition 15 in Table 1, the thickness of the folded portion is as thin as 8 μm on average, and the reliability becomes low. On the other hand, when the external electrode is formed under the conditions 16 to 18, the thickness of the folded portion is 20 on average.
Since it is more than μm, there is no problem in reliability. For this reason,
The velocity C must be at least 0.5 mm / s.

Thus, the dipping speed and the initial pulling speed of the monolithic ceramic capacitor in the conductive paste are set to a predetermined speed of 0.5 mm / sec or less, and the second pulling speed is set to a predetermined speed of 0.5 mm / sec or more. By this, a stable external electrode can be formed.

Next, a method of manufacturing the monolithic ceramic capacitor according to the second embodiment will be described with reference to FIG.

FIG. 2 (a) is a diagram showing the relationship between the end face position of the monolithic ceramic capacitor and time in the step of immersing and pulling up the monolithic ceramic capacitor in the conductive paste bath, and FIG. It is a figure showing a list of speed conditions.

In the monolithic ceramic capacitor according to the present embodiment, the ceramic sintered body is immersed in the conductive paste at a speed (speed A) and pulled out from the conductive paste.
The pulling-up speed (speed B) of No. 1 was shaken. Other details are the same as in the case of the laminated ceramic capacitor shown in the first embodiment.

The results of measuring the folded back thickness of the laminated ceramic capacitor thus formed are shown in Table 2.
Shown in.

[0045]

[Table 2]

As shown in Table 2, the turnback thickness increases as the first pulling rate increases, regardless of the dipping rate. This is because the conductive paste once attached to the ceramic sintered body flows downward as the pulling rate is slower.

As described above, the thickness of the folded portion can be controlled by adjusting the first pulling rate. That is, when the monolithic ceramic capacitor is mounted on a circuit board or the like, the height of the external electrodes on the surface facing the board can be controlled. This suppresses the occurrence of the tombstone phenomenon during mounting due to this high height,
Mounting defects can be reduced.

Next, a method of manufacturing the monolithic ceramic capacitor according to the third embodiment will be described with reference to FIG.

FIG. 3 is a diagram showing the relationship between the end face position of the monolithic ceramic capacitor and time in the process of immersing and pulling up the monolithic ceramic capacitor in a conductive paste bath. It is the figure which showed the list.

The external electrodes of the monolithic ceramic capacitor according to the present embodiment are formed by immersing them twice in a conductive paste, as shown in FIG.

The first immersion (dip) is the same as in the above-mentioned embodiment, the monolithic ceramic capacitor is immersed in the conductive paste (speed D), stopped for a predetermined time (time G1), and then the first pulling speed ( It is pulled up at a speed E), and is pulled up from a predetermined position at a second pulling speed. The second immersion (dip) is the first pulling speed (speed F).
When changing from to the second pulling speed (speed H), the motor is temporarily stopped at a predetermined position (stop position L2) for a predetermined time (time G2). Here, the first immersion (dip)
The experiment was conducted by changing the conditions of the second (final) immersion (dip) without changing the conditions of. The parameters are speed F, stop position L2, time G2, and speed H, and the number of defective defects such as bubble encroachment and dent under each condition and the turnback thickness were measured. In this experiment, the height of the conductive paste liquid surface was 550 μm in the first immersion tank and 150 μm in the first immersion tank from the bottom of the paste tank.
Is.

The results of this experiment are shown in Table 3.

[0053]

[Table 3]

As shown in Table 3, when the external electrode is formed under the condition 6, bubbles and dents occur. That is,
The problem cannot be solved when the first pulling speed (speed F) is 0.5 mm / second or more and the stop is not stopped (stop time is 0 second).

When the external electrode is formed under the condition 1, bubbles and dents do not occur, but the thickness is less than 10 μm, which is the external electrode thickness that can normally maintain reliability, which is a problem. That is, if the second pulling speed (speed H) is slower than 0.5 mm per second, reliability problems occur.

Also, when the external electrode is formed under the condition 11, the thickness of the external electrode is similarly less than 10 μm. This is because the stop position L2 was too high and the conductive paste flowing downward increased.

From the above, only when the following conditions are satisfied,
A monolithic ceramic capacitor having high reliability can be easily and stably manufactured.

The first pull-up speed is 0.5 mm / sec or less, the second pull-up speed is 0.5 mm / sec or more, the speed is temporarily stopped for a predetermined time at the time of speed switching, and the stop position is the paste position from the bottom surface of the paste tank. The position is 1.5 times or less the height of the conductive paste from the bottom of the tank. The second pulling speed is 0.5 mm / sec or more, the speed is temporarily stopped for a predetermined time when the speed is switched, and the stop position from the bottom of the paste tank is 1.5 times or less the height of the conductive paste from the bottom of the paste tank. And the position.

In this embodiment, the immersion is performed twice, but the number of times is not particularly limited, and the above conditions may be applied in the final immersion.

Further, in the above-described embodiment, the description was made using the laminated ceramic capacitor, but the present invention is not limited to the capacitor, but can be applied to a ceramic electronic component in which external electrodes are formed by applying a conductive paste.

[0061]

According to the present invention, the speed of immersion in the conductive paste stored in the paste tank of the component end surface is 0.5 mm or less per second, and when the component end surface is pulled up,
When the height of the part end surface from the bottom of the paste tank is within 1.5 times the height from the bottom of the paste tank to the liquid level of the conductive paste, when the part end surface is 0.5mm / sec. In the range where the height is more than 1.5 times, the pulling-up speed of the component is set to 0.5 mm / sec or more to suppress the occurrence of defects related to the external electrode and form the external electrode with a stable film thickness. Ceramic electronic components can be manufactured.

Further, according to the present invention, the immersion speed of the end face of the component in the conductive paste stored in the paste tank is set to 0.5 mm / sec or less, and when the end face of the component is pulled up, the bottom face of the paste tank is removed from The height of the component is within 1.5 times the height from the bottom surface of the paste tank to the liquid level of the conductive paste, when the component end surface is located, the pulling is temporarily stopped for a certain period of time, and the pulling speed after the stop. Is 0.5 mm / sec or more, the external electrodes can be formed more stably, and a highly reliable ceramic electronic component can be manufactured more stably.

Further, according to the present invention, the external electrode is formed by dipping and pulling up the conductive paste to the end face of the component a plurality of times, and the final dipping and pulling method of this series is the above-mentioned external electrode forming method. By doing so, a more stable and highly reliable ceramic electronic component can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an end face position and time of a monolithic ceramic capacitor according to a first embodiment, and a diagram showing a list of speed conditions thereof.

FIG. 2 is a diagram showing a relationship between an end face position and time of a monolithic ceramic capacitor according to a second embodiment, and a diagram showing a list of speed conditions thereof.

FIG. 3 is a diagram showing a relationship between an end face position and time of a monolithic ceramic capacitor according to a third embodiment, and a diagram showing a list of speed conditions thereof.

FIG. 4 is a state diagram of the conductive paste and external electrodes in the process of immersing the electronic component in the conductive paste and pulling it up.

FIG. 5 is a state diagram of the conductive paste and external electrodes in the process of immersing the electronic component in the conductive paste and pulling it up.

[Explanation of symbols]

1-electronic components 11-External electrode 2-conductive paste 3-paste tank 4-void 5-Dent part of the external electrode 11 6-Bubbles in the external electrode 11

Claims (3)

[Claims] 1. A method for producing a ceramic electronic component, wherein an external electrode is formed by immersing an end face of a component in a conductive paste stored in a paste tank, and then pulling it up, drying and firing it. Is 0.5 mm or less per second, and the height of the component end surface from the bottom surface of the paste tank is 1.5 times the height from the bottom surface of the paste tank to the liquid surface of the conductive paste when the component end surface is pulled up. When the end face of the component is within a range of double, the pulling speed of the component is 0.5 mm / sec or less, and when the height is more than 1.5 times, the pulling speed of the component is 0.5 mm / sec or more. A method for manufacturing a ceramic electronic component, comprising: 2. A method of manufacturing a ceramic electronic component, wherein an external electrode is formed by immersing an end face of a component in a conductive paste stored in a paste tank, and then pulling it up, drying and firing it. Is 0.5 mm or less per second, and the height of the component end surface from the bottom surface of the paste tank is 1.5 times the height from the bottom surface of the paste tank to the liquid surface of the conductive paste when the component end surface is pulled up. A method for manufacturing a ceramic electronic component, wherein when the component end face is within a range of twice, the pulling is temporarily stopped for a certain period of time, and the pulling rate after the stop is 0.5 mm / sec or more. 3. The manufacturing according to claim 1, wherein the conductive paste is dipped and pulled up to the end face of the component a plurality of times, and the final dipping and pulling out of the plurality of dipping and pulling up is performed. Method for manufacturing a ceramic electronic component using the method.