JPS6235255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing method suitable for manufacturing chip-shaped ceramic capacitors.

BACKGROUND OF THE INVENTION As various electronic and electrical circuits are becoming more densely packaged and lower voltages, there is a strong desire for capacitors used as circuit elements to be smaller and larger in capacity. A chip-shaped multilayer ceramic capacitor is known as a capacitor suitable for this purpose. Chip-shaped multilayer porcelain capacitors are easy to miniaturize and increase capacity.
It has excellent features such as being able to be bonded to a flat conductive pattern, meeting the demands for high-density packaging, and having a uniform external shape, allowing for automatic insertion and assembly when mounted on a printed circuit board, etc.

By the way, when manufacturing chip-shaped multilayer porcelain capacitors, the finished dimensions are very small, about 3 x 5 m/m, and the thickness is about 1 mm, making it difficult to handle. Due to the necessity of forming internal electrodes and exposed electrodes within a narrow area, it is extremely difficult to manufacture a single magnetic capacitor from the beginning to the end of the manufacturing process. Therefore, conventionally, as shown in Figure 1, a plastic film called a green sheet A 1 made of a high dielectric constant porcelain material such as barium titanate or titanium oxide to a thickness of around several tens of _microns was used. Above, platinum, palladium, etc., 1100
A sheet S 1 on which multiple electrode patterns B ₁ are printed at predetermined intervals using an electrode material made of a noble metal with a high melting point that can withstand a firing temperature of ~1400°C, and a sheet S ₁ with electrode patterns B ₁ printed on a plastic film A ₂ as well. The electrode pattern B ₂ , which is oriented in the opposite direction, is superimposed on the sheet S ₂ , which is a plurality of sheets printed at equal intervals to the sheet S ₁ (FIG. 1A), and then the electrode patterns B ₁ and B are printed. The part ₂ was punched out using a press P ₁ etc. (Figure 1B)
This was then formed and sintered at a firing temperature of 1,100 to 1,400°C.

However, in this manufacturing method, each sheet S ₁ ,
Since S ₂ is highly flexible and difficult to handle, it is troublesome to accurately position and overlap each sheet S ₁ and S ₂ , resulting in poor productivity and
Since the overlapping positions of S ₁ and S ₂ tend to shift, as shown in Fig. 2, when end electrodes T ₁ and T ₂ are provided, internal electrode patterns B ₁ and B ₂ that are not electrically conductive are generated. However, there have been cases where accidents have occurred where the capacity is insufficient or the capacity is not available at all.

In addition, the printing position of the electrode patterns B ₁ and B ₂ on the flexible films A ₁ and A ₂ may be misaligned, and the films A ₁ and A ₂ may be
A similar problem has arisen due to the difference in shrinkage rate between the two, which is based on the difference in thermal expansion coefficient between the electrode material and the electrode material.

For this reason, ±
When trying to obtain capacitance values with extremely narrow tolerances such as 5%, ±2.5%, ±1%, etc., an extreme drop in yield is seen, and it is necessary to carefully select high-quality and highly reliable products. However, the disadvantage was that the product cost was high. Particularly recently, there has been an increase in demand for multilayer ceramic capacitors with high mounting density in consumer equipment such as televisions and radios, as well as demands for low cost and high reliability, and improvements have been strongly desired.

The present invention eliminates the above-mentioned conventional drawbacks, accurately positions the dielectric ceramic layer and the electrode pattern, and at the same time forms the dielectric ceramic layer to a predetermined thickness with high precision. The object of the present invention is to provide a manufacturing method capable of manufacturing high-quality, highly reliable, compact and large-capacity chip-shaped ceramic capacitors with very small capacitance variations at high speed.

In order to achieve the above object, a method for manufacturing a multilayer ceramic capacitor according to the present invention includes a step of gravure transferring a dielectric ceramic layer onto a base film, and a step of drilling holes at regular intervals on the base film. The present invention is characterized by comprising a step of alternately laminating and forming electrode patterns and dielectric ceramic layers by gravure transfer on the dielectric ceramic layer of the base film fed through the holes as feeding holes.

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. FIG. 3 is a diagram illustrating a manufacturing line that implements the manufacturing method according to the present invention.

In the figure, reference numeral 1 denotes a base film, which is made of a heat-resistant material such as Kapton (registered trademark) or polyimide film. In this embodiment, the base film 1 is arranged in an endless manner, and while being conveyed as indicated by arrow P,
Each necessary step a ₁ to a ₇ is performed repeatedly.

First, in step _a1 , a gravure transfer device 2 is provided. As shown in FIG. 4, the gravure transfer device 2 is composed of a gravure cylinder 2b that rotates within an ink pan 2a, a presser roll 2c that presses the base film 1 onto the gravure cylinder 2b, and a doctor blade plate 2d. There is.

The ink pan 2a contains a dielectric ceramic paste made of a high dielectric constant ceramic powder such as barium titanate or titanium oxide, a binder, and an appropriate amount of water.

When applying the above-mentioned porcelain paste onto the base film 1, the gravure cylinder 2b is rotated in the same direction in synchronization with the transfer speed of the base film 1. Then, the porcelain paste absorbed into the grooves on the surface of the gravure cylinder 2b is transferred to the blade plate 2.
d, and a dielectric ceramic paste coating film of a constant thickness is transferred onto the base film 1.

Figure _5a1 shows the dielectric ceramic layer 3 as described above.
The dielectric ceramic layer 3 is shown on the periphery 1a, 1b of the base film 1.
It is applied in a continuous band in an area separated by a gap g ₁ from .

The reason why the gravure transfer method was applied to apply the porcelain paste is as follows.

Traditionally, the method for forming porcelain paste coatings is as follows:
The doctor blade method or screen printing method was common. However, these methods had the following drawbacks.

(1) Doctor blade method The doctor blade plate is fixed, and as the traveling speed of the base film increases, the relative speed between the two increases, making it difficult to apply the porcelain paste to a uniform thickness. There is a limit to the improvement in mass productivity by increasing speed. Furthermore, since the thickness of the porcelain paste coating is determined by the gap formed between the surface of the base film and the doctor blade plate, it is difficult to control the coating thickness to a constant thickness, making it difficult to control the coating thickness with high precision. Not suitable for manufacturing capacitors.

(2) Screen printing method It is relatively easy to control the thickness of the porcelain paste coating, but the porcelain paste must be printed while the base film is running, which has the disadvantage of lacking mass productivity.

In the present invention, as described above, since the dielectric ceramic layer is formed by the gravure transfer method, the following excellent effects can be obtained.

(1) Since the relative speed between the base film 1 and the gravure cylinder 2b becomes zero, the dielectric ceramic paste can be applied at high speed, and manufacturing efficiency and mass productivity are significantly improved.

(2) Since the fixed amount scratched by the doctor blade plate 2d is transferred, the variation in the thickness of the porcelain paste coating film is reduced, and a capacitor with high precision and constant quality can be obtained. Moreover, since it is easy to reduce the coating thickness, it is also easy to obtain a large capacity capacitor.

Next, after the gravure transfer step _a1 , the dielectric ceramic layer ₃ on the base film 1 is heated to a temperature of 60 to 120°C by the heating device 4 provided in the step _a2 . Heat and dry at a temperature of about 1 hour.

Next, after going through feed adjustment and rolling process a ₃ , process a ₄
In this step, holes are punched at regular intervals on the base film 1 by the punching device 5. Figure 5 a ₄ is
A part of the base film 1 after this step _a4 is shown, and the holes 6 are continuously provided at a constant interval _d1 on the periphery of the base film 1.

Note that this punching step _a4 can also be provided before the gravure transfer step _a1 .

After punching process _a4 , base film 1
is led to step _a5 . A printing machine 7 for printing electrodes is provided in step _a5 , and the printing machine 7 prints an electrode pattern on the dielectric ceramic layer 3 on the base film 1. Base film 1 for process a ₅
The feeding of the base film 1 and the withdrawal of the base film 1 from step _a5 are performed by connecting the sprockets 8 and 9 arranged on both sides of the printing machine 7 to the holes 6 provided on the base film 1.
This is done by meshing with and applying feed using this. This is because, with such a configuration, the electrode printing position on the base film 1 can be accurately positioned using the hole 6 as a reference. In other words, the amount of rotation of sprockets 8 and 9 is based on the amount of rotation of base film 1.
Therefore, by determining the printing position from the amount of rotation of the sprockets 8 and 9, temporarily stopping the base film 1 at that position, and then driving the printing machine 7, the base film 1 is Electrode patterns can be printed at regular intervals on the upper dielectric ceramic layer 3. Figure 5
a ₅₁ and a ₅₂ are thus formed into electrode patterns X ₁ to X _o
1 shows a partial plan view and a sectional view of a base film 1 printed with . In this embodiment, the electrode patterns X ₁ to _{X o} are printed in a matrix on the dielectric ceramic layer 3 , and the set of electrode patterns X ₁ to _{X o} is arranged in a fixed pattern defined by the holes 6 Printing is performed sequentially in the length direction of the base film 1 at intervals of D ₁ .

Note that as the electrode material, a metal with a high melting point that can withstand a firing temperature of 1100 to 1400°C, such as a noble metal paste such as platinum, palladium, or a silver-palladium alloy, is used.

Further, the printing machine 7 may be constructed by a normal screen printing machine, but is preferably constructed by a hot melt screen printing machine. This is because the use of a hot melt screen printing machine allows the subsequent electrode drying step _a7 to be omitted, resulting in a reduction in equipment costs and an improvement in manufacturing efficiency due to the shortening of the process.

When the printing machine 7 is a normal screen printing machine or the like, after passing through the feed adjustment and rolling process _a6 , the base film 1 is guided to the process _a7 , and is heated by a heating device provided in the process _a7 . 10, the electrode patterns X ₁ to _{X o} printed on the dielectric ceramic layer 3 are heated and dried at a temperature of 60 to 120° C. for about 30 minutes.

The base film 1 that has gone through the heating and drying step _a7 is guided by rollers 11 and 12 and returned to the step _a1 again.
Similar steps _a1 to _a7 are repeated as many times as necessary.

FIGS. 6A and 6B show a partial plan view and a cross-sectional view of the base film 1 after repeating each of the above steps a ₁ to _{a 7} twice; One dielectric ceramic layer 3, electrode pattern X
It has a laminated structure.

Note that in step _a4 , at the same time as punching the holes 6, electrode patterns X ₁ to X _o are formed as shown in FIG.
A dividing groove S is carved so as to surround the area to be printed,
A single capacitor can also be taken out by indexing along the dividing groove S after sintering.

Further, in the embodiment, the base film 1 is endless, but the base film 1 may have an end instead of an endless shape, and may be configured to run between a supply roll and a take-up roll. In this case, the base film that has gone through steps a ₁ to _{a 7} is wound onto a take-up roll, and then passed through steps a ₁ to a ₇ again, and this is repeated the necessary number of times. A possible method is to make the reciprocating movement between the reel and the take-up roll the necessary number of times and repeat steps _a1 to _a7 each time, and a method as shown in Figs. 8 to 10 is also considered. It will be done.

First, the method shown in FIG. 8 involves winding up the base film 1A after passing through steps _{a 1} to a ₇ onto a take-up roll, and then using this base film 1A to repeat steps a ₁ to a ₇ . This is a method of passing. In the figure 1
3 is a guide roll, and 14 is a calendar roll.

Next, in the method shown in FIG. 9, the base film 1A after passing through steps a ₁ to a ₇ is wound onto a take-up roll 15, and this base film 1A is transferred to the base film 1A immediately after completing steps a ₁ in FIG. 4. First, the dielectric ceramic layer 3 coated on the base film 1B is bonded using an adhesive roll 16 and smoothed using a calender roll 17, after which steps _a2 and subsequent steps are performed.

The method shown in FIG. 10 uses a heater 18 and heat rolls 19 to 22 to thermally bond the base film 1A onto the base film 1B.

As described above, a dielectric ceramic laminated strip in which dielectric ceramic layers 3 and electrode patterns X are alternately laminated is manufactured. In order to make this into a capacitor, each set of electrode patterns X ₁ to X _o may be cut and then fired. As a result, the dielectric ceramic layer 3 is sintered, and at the same time the base film 1 is burned out and the 11th
A capacitor assembly as shown in FIG. 12 is obtained. The capacitor assembly has each electrode pattern
Capacitor elements Q ₁ to _{Q o} are formed in each region of X ₁ to _{X o} , and each capacitor element Q ₁ to Q _o is cut vertically and horizontally to separate each capacitor element Q ₁ to Q _o individually. Take it out. In this case, if a dividing groove S as shown in FIG. 7 is provided, the capacitor elements Q ₁ to Q _o can be easily and easily taken out by folding vertically and horizontally along the dividing groove S. .

Each of the capacitor elements Q ₁ to _{Q o} is coated with an end electrode and a protective film, and a multilayer ceramic capacitor as shown in FIG. 13 is completed. In addition, the 13th
Although the figure shows a multilayer ceramic capacitor, the number of dielectric ceramic layers and electrode patterns can be selected arbitrarily, so it can be a single-plate ceramic capacitor, or it can be a multilayer ceramic capacitor. Of course, this is also possible.

As described above, the method for manufacturing a ceramic capacitor according to the present invention includes a step of gravure transferring a dielectric ceramic layer onto a base film, a step of drilling holes at regular intervals on the base film, and a step of forming holes at regular intervals on the base film. The present invention is characterized by including the step of sequentially laminating and forming an electrode pattern and a dielectric ceramic layer by gravure transfer on the dielectric ceramic layer on the base film that is fed as a feed hole, so that it has the following effects. .

(1) Even when electrode patterns are printed in multiple layers, there is no printing misalignment, and it is possible to efficiently manufacture high-quality, highly reliable, compact, large-capacity ceramic capacitors with very small capacitance variations.

(2) Since the dielectric porcelain layer is formed by gravure transfer, (a) The relative speed between the film and the gravure cylinder is zero, and the dielectric porcelain paste is applied at high speed, significantly improving mass productivity. can be done.

(b) Variations in the thickness of the porcelain paste coating film are reduced, making it possible to manufacture high-precision capacitors.

(c) The porcelain paste coating film is extremely thin, making it possible to manufacture large-capacity capacitors with low working voltage.

(3) As shown in the examples, by forming the electrode pattern by hot-melt screen printing, the drying process of the electrodes can be omitted, improving manufacturing efficiency and reducing costs.

[Brief explanation of the drawing]

Figures 1A and B are diagrams explaining the conventional manufacturing method of a ceramic capacitor, Figure 2 is a diagram explaining the drawbacks of the multilayer ceramic capacitor manufactured according to Figure 1, and Figure 3 is a diagram explaining the present invention. FIG _. 4 is a perspective view of _the gravure transfer device, _{and FIG .} Figures 6A and 6B are diagrams illustrating the structure of the base film, and Figure 7 is a diagram illustrating the structure of the base film in the final step. Figure 7 is a base manufactured by another method of the manufacturing method according to the present invention. Partial plan view of film, No. 8
9 and 10 are diagrams explaining other embodiments of the manufacturing method according to the present invention, and FIG. 11 is a partially cutaway plan view of a capacitor assembly manufactured by the manufacturing method according to the present invention. , FIG. 12 is a sectional view taken along line CC in FIG. 11, and FIG. 13 is a sectional view of a multilayer ceramic capacitor manufactured by the manufacturing method according to the present invention. 1...Base film, 2...Gravure transfer device,
3...Dielectric ceramic layer, _X1 to _Xo ...electrode pattern.

Claims (1)

[Claims] 1. A step of gravure transferring a dielectric ceramic layer onto a base film, a step of drilling holes at regular intervals on the base film, and a step of forming holes on the dielectric ceramic layer of the base film fed using the holes as feeding holes. 1. A method for manufacturing a ceramic capacitor, comprising a step of alternately laminating and forming dielectric ceramic layers using an electrode pattern and gravure transfer.