JPS6232603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ceramic capacitor, particularly a ceramic capacitor that allows for electrode trimming.

Ceramic capacitors can be made small and have a large capacity, can be bonded to a flat conductive pattern and are easy to handle, are suitable for high-density packaging, can be used up to high frequency bands, and have a relatively uniform external shape. It is easy to assemble automatically,
It has excellent features such as being suitable for mass production, and demand is only increasing as electronic and electrical equipment becomes more sophisticated and densely packaged.

Incidentally, after actually incorporating these ceramic capacitors into a circuit board or the like, it may be necessary to adjust the capacitance of the magnetic capacitors. A good example is a crystal oscillator circuit in a wristwatch. In such cases, conventionally, a trimmer type ceramic capacitor has been used to perform variable adjustment of the capacitance.

However, since trimmer-type ceramic capacitors have mechanically movable parts, the capacitance value tends to change due to vibrations and the like after capacitance adjustment, resulting in a lack of reliability.

Further, trimmer type ceramic capacitors have the problem of being expensive and large in size, and cannot meet the demands for cost reduction and high-density packaging of equipment.

For this reason, recently, a ceramic capacitor having a structure in which the capacitance is adjusted by trimming the electrodes has been proposed in place of the trimmer type ceramic capacitor.

1 and 2 show partially cutaway perspective views of a trimmable ceramic capacitor.

First, the ceramic capacitor shown in Figure 1 is made of barium titanate, titanium oxide, etc. and has a thickness of 50 to 100 μm.
An exposed electrode 3 constituting a counter electrode with the internal electrode 2 is provided on the surface of the porcelain dielectric 1 of approximately
The capacity is adjusted by reducing the amount of data. Reference numerals 4 and 5 indicate extraction electrodes electrically connected to the internal electrode 2 and the exposed electrode 3, which are formed on two opposing sides.

Next, the ceramic capacitor shown in FIG. 2 has a structure in which the exposed electrode 3 is composed of a coarse capacitance adjustment section 3a and a fine capacitance adjustment section 3b, and the capacitance can be easily and precisely adjusted. .

The above-mentioned ceramic capacitor works as a fixed capacitor after the capacitance is adjusted by trimming the exposed electrode 3, so it has very high reliability. Furthermore, since the external shape is unified, and the device is small and thin, it can fully satisfy automatic assembly and high-density packaging when mounted on a circuit.

By the way, when obtaining trimmable ceramic capacitors such as those shown in Figs. 1 and 2, the finished dimensions are very small, for example, about 3 x 5 m/m, and the thinness makes it difficult to handle. In order to reinforce the porcelain dielectric material 1, which is very thin and has low mechanical strength of about 50 to 100 μm, it is necessary to have a laminated structure backed by a reinforcing layer 6 of the same quality.
Furthermore, manufacturing is not necessarily easy because it is necessary to form internal electrodes 2 and meandering exposed electrodes 3 within a narrow area of about 3×5 m/m.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a ceramic capacitor that can efficiently manufacture the trimmable ceramic capacitors shown in FIGS. 1 and 2.

To achieve the above object, the present invention provides a method for manufacturing a ceramic capacitor having exposed electrodes on the surface of a ceramic dielectric in which internal electrodes are embedded, in which a first ceramic dielectric sheet before firing is A step of carving slits in a grid shape on the surface and printing and applying a conductive pattern to become the internal electrodes in each area divided by the slits, and applying the conductive pattern to the first porcelain dielectric sheet. a step of pasting a second porcelain dielectric sheet before firing on the surface and carving a slit corresponding to the slit on the surface; 2
The present invention is characterized in that it includes a step of printing and applying a conductive pattern to become an exposed electrode in each region defined by the slit on the surface of the porcelain dielectric sheet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically explained in detail below with reference to the accompanying drawings which are examples.

3a to 3j are explanatory views of the manufacturing process of the ceramic capacitor according to the present invention.

First, a first rectangular porcelain dielectric sheet A is made by punching or the like from a porcelain dielectric sheet before firing (FIG. 3a). This first ceramic dielectric sheet A serves as the reinforcing layer 6 in FIGS. 1 and 2, and is preferably formed relatively thick. In terms of material, it is desirable to use barium titanate or titanium oxide based porcelain, which is the same as the second porcelain dielectric sheet, in order to improve the texture during firing and sintering.

Next, as shown in FIG. 3b, slits S ₁ and S ₂ are carved in a grid pattern on the surface of the first porcelain dielectric sheet A. Since the first porcelain dielectric sheet A is in a state before firing and sintering, the slits S ₁ and S ₂ can be easily carved. Further, at least one of the slits S ₁ and S ₂ , for example, the slit S ₁ , is provided so as to reach the two relative sides A ₁ and A ₂ of the porcelain dielectric sheet A, so that it can be divided along the slit S ₁ after sintering. do. Note that it is desirable that the slits S ₁ and S ₂ be provided on the front and back sides of the ceramic dielectric sheet A.

After carving the slits S ₁ and S ₂ , the slits S ₁ and
In each area a ₁ to a _o divided by S ₂ , the first
Conductive patterns P ₁ to P which become the internal electrodes 2 in Fig. 2
_o is printed and coated using a screen printing method or the like (Fig. 3C). In this case, the conductive patterns P ₁ to _{P o} are
Since it will be necessary to electrically connect to the extraction electrode later, it is printed and coated so that one edge is located above the slit _S1 . Note that the conductive patterns P ₁ to P are formed by printing and applying a noble metal paste such as platinum, palladium, or silver-palladium alloy in order to withstand the firing temperature.

Next, on the surface of the second porcelain dielectric sheet A on which the conductive patterns P ₁ to _{P o} have been printed and coated as described above,
A second porcelain dielectric sheet B, which acts as a substantial capacitor, is attached, and slits S _{' 1} and S _{' 2} are formed on the surface of the second porcelain dielectric sheet B, tracing over the slits S ₁ and S _2. (Fig. 3 d). The second porcelain dielectric sheet B is made of barium titanate or titanium oxide based porcelain and is formed as an extremely thin flexible sheet of about 50 to 100 μm.
When laminated on a ceramic dielectric sheet A, the slits S ₁ and S ₂ can be seen through. Therefore, it is easy to cut the slits S' ₁ and S' ₂ to match the slits S ₁ and S ₂ .

As described above, after the second porcelain dielectric sheet B is laminated onto the first porcelain dielectric sheet A, both are fired and sintered by ordinary firing means. As a result, the first ceramic dielectric sheet A and the second ceramic dielectric sheet B are integrally sintered, and the conductive patterns P ₁ to
A hard porcelain dielectric with embedded P _o is formed.
Note that the first and second porcelain dielectric sheets A and B change color to dark brown due to sintering, but the slits S ₁ , S ₂ ,
S' ₁ and S' ₂ remain as they are, and the slits S' ₁ and S' ₂ can be visually confirmed.

After the firing process, the second porcelain dielectric sheet B
In each region b ₁ to b o demarcated by slits S' ₁ and S' _{2 and} on slit S' ₁ (or slit S' ₂ ) on the surface that was Conductive patterns _Q1 to _Qo , which will become the exposed electrodes 3 in the figure, are printed and coated by screen printing or the like. Note that the conductive pattern was also applied on the slit S′ ₁ to form a surface-extracted electrode pattern for the conductive patterns P ₁ to _{P o} that will become the internal electrodes 2 and the conductive patterns Q ₁ to Q _o that will become the exposed electrodes 3. Therefore, the first
It is desirable to print and apply a similar conductive pattern _T1 also along the slits _S1 on the surface of the porcelain dielectric sheet A. After printing and applying the conductive patterns _Q1 to _Qo , a glass layer is printed and applied on the entire front and back surfaces (Fig. 3g) to form the conductive patterns.
A protective coating is formed on Q ₁ to _{Q o} and then a bending force is applied along the slits S ₁ and S' ₁ . slit
Some parts of S ₁ and S′ ₁ have weaker mechanical strength than other parts, and the entire porcelain dielectric has increased hardness through firing, so the porcelain dielectric has a slit.
It is bent along S ₁ and S′ ₁ and separated from each other.

A conductive layer, which will become the extraction electrode, is applied with a brush to both end faces C ₁ and C ₂ of the chip obtained in this way (Fig. 3 h), and then the chip is placed in a heating furnace to form a conductive pattern Q. ₁ to _Qo and the glass layer are fixed by baking (Figure 3i). Upon completion of this baking process, the opaque glass layer changes to transparent, and the conductive patterns Q ₁ to _{Q o} become visible from the surface. In actual use, conductive pattern
Cut out each part containing each of Q ₁ to Q _o . Since each of the conductive patterns Q ₁ to Q _o is divided by the slit S ₂ as described above, division from this portion S ₂ is possible.

Through this dividing operation, a finished product of a ceramic capacitor as shown in FIGS. 1 and 2 is obtained (FIG. 3 j). In a method for manufacturing a ceramic capacitor having exposed electrodes on the surface of the body, slits are carved in a grid pattern on the surface of a first ceramic dielectric sheet before firing, and the slits are partitioned by the slits. a step of printing and applying a conductive pattern that will become the internal electrode in the area where the conductive pattern is applied, and bonding a second ceramic dielectric sheet before firing on the conductive pattern coated surface of the first ceramic dielectric sheet, and applying a second ceramic dielectric sheet to the surface thereof. a step of carving a slit corresponding to the slit, and a step of carving a slit corresponding to the slit in the area defined by the slit on the surface of the second porcelain dielectric sheet after firing the first and second porcelain dielectric sheets. Since the method includes a step of printing and applying a conductive pattern that becomes the exposed electrode, a large number of ceramic capacitor elements as many as the number partitioned by the slits are formed on one ceramic dielectric plate at once. However, this ceramic capacitor element can be easily taken out by separating it from each other along the slit. Therefore, the trimmable ceramic capacitors shown in FIGS. 1 and 2 can be easily mass-produced.

Note that a multilayer ceramic capacitor having exposed electrodes and capable of trimming can also be easily manufactured by the same process.

[Brief explanation of the drawing]

1 and 2 are partially cutaway perspective views of a trimmable ceramic capacitor, and FIGS. 3 a to 3 j are process explanatory diagrams of a method for manufacturing a ceramic capacitor according to the present invention. DESCRIPTION OF SYMBOLS 1...Porcelain dielectric material, 2...Internal electrode, 3...Exposed electrode, A...First ceramic dielectric sheet, B...
Second porcelain dielectric sheet, S ₁ , S ₂ , S′ ₁ , S′ ₂ ……
Slit, P ₁ ~ P _o ... Conductive pattern, Q ₁ ~ _{Q o} ......
conductive pattern.

Claims (1)

[Claims] 1. In a method for manufacturing a ceramic capacitor having exposed electrodes on the surface of a ceramic dielectric material in which internal electrodes are embedded, slits are carved in a grid pattern on the surface of a first ceramic dielectric sheet before firing. a step of printing and applying a conductive pattern to become the internal electrode in the area defined by the slit, and applying a second porcelain dielectric material on the conductive pattern-coated surface of the first porcelain dielectric sheet before firing. bonding the body sheets and carving a slit corresponding to the slit on the surface thereof; and after firing the first and second porcelain dielectric sheets, the second porcelain dielectric sheet is A method for manufacturing a capacitor, comprising the step of printing and applying a conductive pattern to become the exposed electrode within a region defined by a slit.