JP3435060B2 - Ceramic green sheet laminating apparatus and laminating method - Google Patents

Description

Detailed Description of the Invention

According to the present invention, when a ceramic green sheet having an internal electrode pattern or an internal circuit wiring pattern is partially laminated to manufacture an electronic component such as a laminated ceramic capacitor or a laminated ceramic inductor, the ceramic green sheet is used. TECHNICAL FIELD The present invention relates to a method and a device for cutting, laminating and crimping.

[0002]

2. Description of the Related Art Examples of laminated electronic components include laminated capacitors, laminated inductors, laminated piezoelectric components, laminated filters, and ceramic multilayer circuit boards.
For example, in a laminated ceramic capacitor, which is the most typical example of a laminated electronic component, a large number of ceramic layers made of a dielectric material having internal electrodes are laminated, and the internal electrodes are alternately drawn out on the end faces of the laminated body which face each other. Has been. External electrodes are formed on the end faces of the laminated body from which these internal electrodes are drawn out, and the external electrodes are connected to the internal electrodes, respectively.

The laminated body 3 of such a laminated ceramic capacitor has, for example, a layered structure as shown in FIG. That is, the ceramic layers 7 and 7 made of a dielectric material having the internal electrodes 5 and 6 are laminated in the order shown in FIG. 7, and the ceramic layers 7 and 7 on which the internal electrodes 5 and 6 are not formed are formed on both sides thereof. Each is stacked in multiple layers. And
The internal electrodes 5 and 6 are exposed on the end surface of the laminated body 3 having such a layer structure, and the external electrodes 2 and 2 as shown in FIG.

Such a laminated electronic component is not manufactured individually as shown in FIG. 7, but in practice, the following manufacturing method is adopted. First, finely pulverized ceramic powder and an organic binder are kneaded to make a slurry, which is thinly spread on a supporting film made of polyethylene terephthalate film or the like by a tape molding method such as a doctor blade method and dried to form a ceramic green sheet. create. Next, this ceramic green sheet is cut into a desired size with a cutter and peeled off from the support film. Further, a conductive paste is printed on one surface of the cut ceramic green sheet by a screen printing method and dried. As a result, as shown in FIG. 8, ceramic green sheets 1a and 1b in which a plurality of sets of internal electrode patterns 2a and 2b are arranged vertically and horizontally are obtained.

Next, as shown in FIG. 8, a plurality of ceramic green sheets 1a and 1b having the internal electrode patterns 2a and 2b are laminated, and some ceramic green sheets 1a and 1b which do not have the internal electrode patterns 2a and 2b are laminated. The ceramic green sheets 1 and 1 are stacked on top of each other, and these are pressure-bonded to each other to form a laminated body. Here, the ceramic green sheet 1
As for a and 1b, the internal electrode patterns 2a and 2b, which are shifted in the longitudinal direction by a half length, are alternately stacked. After that, cut this laminate to the desired size,
A laminated raw chip is manufactured and the raw chip is fired. In this way, a laminate having a layer structure as shown in FIG. 7 is obtained.

Next, a conductive paste is applied to both ends of the fired laminated body 3 and baked to form the laminated electronic component in which the external electrodes 2 and 2 are formed on both ends as shown in FIG. The ceramic capacitor is completed. In FIG. 5, reference numerals 5 and 6 denote internal electrodes facing each other with the ceramic dielectric layer inside the laminated body 3, and are connected to the external electrodes 2 and 2 at the end faces of the laminated body 3, respectively.

[0007]

In the multilayer capacitor manufactured by the above-described lamination method, the obtained sintered laminate has a structural defect such as delamination phenomenon or crack called delamination. Or the ceramic green sheets 1a and 1b having the internal electrode patterns 2a and 2b are moved or deformed at the time of stacking, which may cause a decrease in stacking accuracy. As a result, the area where the internal electrodes face each other is reduced, the electrostatic capacity is reduced, and product defects occur.

Therefore, as a method for preventing the above-described deterioration of the stacking accuracy, the ceramic green sheets 1, 1 are used.
In order to improve the adhesion between the ceramic layer and the internal electrode portion and the ceramic layer and the ceramic layer when laminating a and 1b,
A method of increasing the adhesion of the organic binder by pressurizing each of the stacked layers in the thickness direction or applying a temperature up to around the softening temperature of the binder in the ceramic green sheets 1, 1a, 1b in order to further improve the adhesion is used. ing.

However, in order to bring the ceramic green sheets 1, 1a, 1b into close contact for each stack, it is necessary to compress and deform the ceramic green sheets by the thickness of the internal electrode patterns 2a, 2b. Or, the heating temperature had to be raised. Therefore, the ceramic green sheet, which is the lower layer, has a large increase in the amount of deformation in the lateral direction when repeatedly pressed. For this reason, for example, as shown in FIG. 6, the elongation of the lower ceramic green sheet becomes larger than that of the upper ceramic green sheet, and the pattern formed on the ceramic green sheet is displaced, causing so-called stacking displacement. As a result, the stacking accuracy and the facing area of the internal electrodes are reduced, and it is not possible to improve the variation or decrease in capacitance.

On the other hand, as a sheet holding condition at the time of stacking, the pressurizing pressure is reduced to 1/2 to 1/20 as compared with the condition that the sheet is not deformed at the time of stacking, that is, the pressure bonding condition of the ceramic laminate, and the heating temperature is increased. When the ceramic green sheets 1, 1a, 1b are laminated at a low temperature of -30 to -100 ° C, the adhesion of the ceramic green sheets 1, 1a, 1b becomes insufficient. As a result, the air remaining between the ceramic green sheets 1, 1a and 1b cannot be completely removed during the pressure bonding, which causes delamination and cracks.

In view of the conventional problems in the above-mentioned ceramic green sheet laminating step, the present invention can completely remove the air remaining between the ceramic green sheets in the ceramic green sheet laminating step. An object of the present invention is to provide a ceramic green sheet laminating method and apparatus capable of suppressing the occurrence of delamination of laminated electronic components caused by residual air between the ceramic green sheets.

[0012]

In the present invention, in order to achieve the above-mentioned object, when the ceramic green sheets b are laminated inside the lower mold 22 and pressure-bonded by the upper mold 12, the ceramic green sheets are laminated. The inside of the lower die 22 on which b is laminated is set to a negative pressure, and the air remaining between the layers of the laminated ceramic green sheets b is removed to the outside of the lower die 22 to perform pressure bonding. is there.

That is, the ceramic green sheet laminating apparatus according to the present invention holds a ceramic green sheet b and carries the carrier 11, and the carrier 11 supplies the ceramic green sheet b to sequentially laminate the ceramic green sheets b. A recess is formed
The lower die 22 and the upper die 12 that pressurizes the ceramic green sheet b laminated inside the lower die 22,
The concave of the lower die 22 for laminating the ceramic green sheets b
Exhaust through the exhaust passage 32 opened at the top and bottom of the side of the section
However, it is characterized by having a pressure reducing means for making the inside of the recess a negative pressure.

Here, the lower mold 22 has a recess for receiving the laminated ceramic green sheets b, and the pressure reducing means exhausts the air in the recess to make the inside of the recess a negative pressure. The upper die 12 may also serve as the carrier 11 that conveys the ceramic green sheet b.

Further, in the ceramic green sheet laminating method according to the present invention, the ceramic green sheet b is held by a carrier and conveyed to the lower mold 22, and the supplied ceramic green sheet b is inside the lower mold 22. While sequentially stacking, one ceramic green sheet b
Or every time a plurality of sheets are laminated ,
The upper mold 12 is characterized in that the laminated ceramic green sheets b are pressurized by exhausting air through an exhaust passage 32 which is opened in the upper and lower sides and maintaining a negative pressure in the concave portion . For example, one ceramic green sheet b
Every time 60 sheets are stacked, pressure is applied between the lower mold 22 and the upper mold 12.

In such a ceramic green sheet laminating apparatus and laminating method, the air between the ceramic green sheets b is generated by laminating the inside of the lower mold 22 on which the ceramic green sheets b are laminated with negative pressure. As a result, the adhesion between the ceramic green sheets b is improved. In particular, the upper and lower sides of the recess of the lower mold 22 were opened.
By exhausting through the exhaust passage 32, the lower mold 22
Depending on the number of ceramic green sheets b stacked on
The upper opening of the exhaust passage 32 when pressurizing
The thickness of the ceramic green sheet b
Optimal exhaust can be performed according to the size. Therefore, the occurrence of defects such as delamination and cracks can be reduced. At the same time, since the adhesion between the ceramic green sheets b is improved, the positional accuracy of the internal electrode patterns is improved.

The depressurized deaeration for the negative pressure is performed every one sheet lamination (every time) to every 60 sheets lamination so that the residual air between the ceramic green sheets b is reduced and the space between the ceramic green sheets b is reduced. Improves the adhesion. The reduced pressure deaeration cycle is set to 60 sheets or less of the ceramic green sheets b every time, and the residual air between the ceramic green sheets b cannot be sufficiently removed by the reduced pressure deaeration cycle higher than that. In other words, in order to sufficiently remove the residual air between the ceramic green sheets b, it is necessary to lengthen the depressurization time, which leads to a decrease in productivity.

When laminating the ceramic green sheets b, the ceramic green sheets b are laminated on the lower surface of the upper mold 11 while being conveyed while being held by means of vacuum suction or magnetic attraction. In the case of the holding means by vacuum suction, it is necessary to make the pressure inside the lower mold 22 lower than that of the vacuum suction. Normally, by setting the negative pressure to be 10% or more lower than the atmospheric pressure for vacuum suction of the ceramic green sheet b, it becomes possible to hold the ceramic green sheet b on the lower surface of the upper mold 11.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings. FIG. 1 is an example of a ceramic green sheet laminating apparatus according to the present invention, and is a side view of a process portion in which a ceramic green sheet b conveyed on a stage 7 is conveyed by a carrier 11 and laminated. 2 and 3 are enlarged views of a main part of a laminating step.

The ceramic green sheet is formed in a state where a ceramic slurry is thinly applied to a support film such as a long polyethylene terephthalate film in a predetermined width to a uniform thickness and dried. The long ceramic green sheet formed on such a support film is
It is cut into a predetermined shape by a cutter and peeled from the support film. Furthermore, by means such as screen printing,
A conductive paste is printed in a predetermined pattern on the cut ceramic green sheet to form an internal electrode pattern. Taking the case of making a laminated body of ceramic green sheets for manufacturing a monolithic ceramic capacitor as an example, two types of internal electrode patterns are printed on some ceramic green sheets, and on some other ceramic green sheets. , Such internal electrode patterns are not printed.

The ceramic green sheets b are sequentially supplied onto the stage 17. On this stage 17,
A carrier 11 is provided which picks up the ceramic green sheet b from the stage 17, conveys it, and supplies it to the lower die 22. The main body of the carrier 11 is an upper mold 12 for adsorbing and holding the ceramic green sheet b cut on the lower surface. The upper mold 12 is provided with a large number of suction holes on the bottom wall, and sucks air from a vacuum source (not shown) so that the bottom surface has a negative pressure, and the cut ceramic green sheet b is adsorbed and held therein. The upper die 12 is moved up and down by an air cylinder 14, and a heater 34 is placed inside the upper die 12.
(See FIGS. 2 and 3). The carrier 11 is wholly shown in FIG.
Move left and right at.

When the ceramic green sheet b is conveyed onto the stage 17, the upper die 12 is lowered, and the lower surface of the die 12 is made a negative pressure to adsorb and hold the ceramic green sheet b . After that, when the upper mold 12 rises, the ceramic green sheet b is picked up from the stage 17 while being held on the lower surface of the upper mold 12. Upper mold 12
When the ceramic green sheet b is adsorbed on the lower surface of
The carrier 11 moves, and as described below, the ceramic green sheet b is pushed into the mold of the lower mold 22 while being pressed and heated to be housed.

The lower die 22 is arranged near the stage 17 and is fixed on a horizontal and stable pedestal 31.
As shown in FIGS. 2 to 1, the lower mold 22 is provided with a recess for stacking and pressing the cut ceramic green sheets b. A heater 33 for heating the ceramic green sheet b in the recess is built in the bottom of the lower mold 22. Further, an exhaust passage 32 is formed on the side surface of the lower mold 22, and the exhaust passage 32 is opened at two upper and lower positions on the side surface inside the recess. Figure 1
As shown in (3), a vacuum pump 35 is connected to the exhaust passage 32, and the inside of the lower mold 22 is exhausted at a proper time by the vacuum pump to a negative pressure.

The ceramic green sheet b conveyed by the carrier 11 as described above is accommodated in the lower mold 22 from the state shown in FIG. 2 as shown in FIG. Placed on and pressurized. At this time, the heater 34 built in the upper mold 12 and the lower mold 22
The ceramic green sheet b is heated at a predetermined temperature by the heater 33 built in the. In this way, whenever one or more ceramic green sheets b are stacked,
With the vacuum pump shown in FIG. 1, as shown in FIG.
During pressurization through the exhaust passage 32, the interior of the lower mold 22 is exhausted to a negative pressure.

In the illustrated example, as shown in FIGS. 2 and 3, since the exhaust passage 32 is opened at two upper and lower positions on the side surface in the recess, the ceramic green sheets b in the lower mold 22 are laminated. When the thickness is thin, as shown in FIG. 3, the opening portion of the exhaust passage 32 on the upper side during pressurization has the upper mold 11
And is exhausted only from the lower opening.
On the other hand, when the laminated thickness of the ceramic green sheet b in the lower mold 22 becomes thick, the exhaust passages 32 on both the upper and lower sides during pressurization.
The opening of opens. In this way, the upper opening of the exhaust passage 32 is opened and closed by the upper mold 22 during pressurization according to the number of layers stacked in the lower mold 22, so that it is optimal according to the stacking thickness of the ceramic green sheet b. Exhaust can be done.

For example, when obtaining a laminated body of ceramic green sheets b for obtaining a laminated ceramic capacitor, a layer of the ceramic green sheet b having no internal electrode pattern, a layer of the ceramic green sheet b having an internal electrode pattern, and an internal electrode. The layers of the ceramic green sheets b having no pattern are sequentially stacked in the lower mold 22 and temporarily pressed. After that, this lower mold 22
It is conveyed to a press such as a hydraulic press, and is finally pressurized and pressure-bonded. Then, the laminated body of the pressed ceramic green sheets b is taken out.

In the above example, the ceramic green sheet b was cut into a quadrangle, but the cut shape is not particularly limited to a quadrangle, and may be cut into a circle or the like. Alternatively, the conductive paste may be formed in a predetermined pattern on the ceramic green sheet by a screen printing method or the like to form an internal electrode pattern, which may be then cut into a predetermined shape with a cutter or the like and peeled from the support film. Further, although the above example mainly explained the lamination of the ceramic green sheets for manufacturing the laminated ceramic capacitor, the method and apparatus for laminating the ceramic green sheets according to the present invention can be applied to, for example, laminated inductors, LC composite parts, multilayer wiring boards, etc. The same can be applied to stacking ceramic green sheets for manufacturing other laminated electronic components.

Further, in the illustrated example, the upper mold 12 is provided on the carrier 11 which holds and conveys the ceramic green sheet b on the lower surface thereof, and also has a function as a carrier. However, the carrier for feeding the ceramic green sheet b and supplying it to the lower die 22 and the upper die for pressing the ceramic green sheet b fed to the lower die 22 may be different from each other.

[0029]

EXAMPLES Next, examples of the present invention will be described by giving specific numerical values. First, a predetermined amount of an organic binder of polyvinyl butyral and an organic solvent of toluene were added to a BaTiO ₃ -based dielectric ceramic raw material powder, sufficiently mixed and dispersed to obtain a slurry. Subsequently, this slurry was formed into a sheet shape on a supporting film made of a polyethylene terephthalate film by a doctor blade method to obtain a thickness of 10
A ceramic green sheet of μm was prepared. A ceramic green sheet having a predetermined shape was cut out from the support film.

A conductive paste was printed in a predetermined pattern on the ceramic green sheet by a screen printing method to form an internal electrode pattern. Next, as described above, the ceramic green sheets were supplied to the lower mold while being vacuum-adsorbed on the lower surface of the upper mold 11, and were sequentially laminated. The stacking order is as follows. First, a predetermined number of layers of ceramic green sheets having no internal electrode pattern are stacked, and then,
A predetermined number of layers of ceramic green sheets having internal electrode patterns were laminated, and finally a predetermined number of layers of ceramic green sheets not having internal electrode patterns were laminated.

At this time, the exhaust passage 32 shown in FIGS.
Is connected to a vacuum pump 35, except for a part of the laminated body,
The inside of the lower die 22 was laminated while being pressure-reduced every one or several sheets and pressure-bonded. Table 1 shows the presence / absence of depressurization, the interval between the depressurized sheets, and the pressurizing time (vacuum pressing time) while maintaining a negative pressure state. “Decompression interval” in Table 1 is an interval of the number of ceramic green sheets that are pressed while the inside of the lower mold 22 is negative pressure, and “Decompression time” in Table 1 is the time of the lower mold 22. It is the time for pressurization while keeping the inside negative pressure.

Atmospheric pressure of the lower mold 22 at the time of decompression is equal to that of the upper mold 11.
Was slightly higher than the atmospheric pressure at which the ceramic green sheet b was sucked. The ceramic laminate thus obtained is fired, cut vertically and horizontally to separate into individual chips, and then external electrodes are formed on both end faces of the obtained sintered laminate. A monolithic ceramic capacitor as shown in was obtained.

Next, 100 of each of the monolithic ceramic capacitors were cut along a plane perpendicular to the internal electrodes 5 and 6 as shown in FIG. 4 and polished to remove delamination between the ceramic dielectric layer and the internal electrode layer and The presence or absence of crack defects was observed with a microscope and the number was counted out of 100. Further, as shown in FIG. 5, the maximum displacement amount Dmax in the width direction of the internal electrodes 5 and 6 was measured with a microscope and evaluated as the stacking accuracy. The results are shown in Table 1.

[0034]

[Table 1]                 Decompression interval Decompression time Defect count Dmax                  (Sheets) (seconds) (pieces) (μm)                                                                                Example 1 1 1.0 0 25                                                                                Example 2 20 1.0 0 32                                                                                Example 3 60 1.0 0 39                                                                                Comparative Example 1 No reduced pressure No reduced pressure 9 165                                                                                Comparative Example 2 120 1.0 8 152                                                                                Comparative Example 3 120 60 2 105                                                                                Comparative Example 4 120 300 0 78                                                                         

As is clear from Table 1, depressurization can be prevented at the time of stacking and at the same time stacking accuracy can be improved. However, if the interval of reduced pressure lamination exceeds 60 layers, deaeration of the residual air (gas) between the ceramic green sheets becomes insufficient, the adhesion between the ceramic green sheets decreases, and delamination easily occurs. Accuracy is also reduced. In Comparative Example 4, the depressurization press time was lengthened, and delamination could be prevented, but no improvement in stacking accuracy was observed. It is presumed that this is because the ceramic green sheets were insufficiently adhered to each other during lamination.

[0036]

As is apparent from the above description, according to the ceramic green sheet laminating apparatus and the laminating method of the present invention, when the ceramic green sheets b are laminated, the inside of the lower mold in which the ceramic green sheets b are laminated. A negative pressure eliminates residual air between the ceramic green sheets, and at the same time improves the adhesion. As a result, it is possible to obtain a high-quality ceramic laminated component with high lamination accuracy without delamination.

[Brief description of drawings]

FIG. 1 is a schematic side view of a ceramic green sheet cutting step and a stacking step portion showing an example of a ceramic green sheet stacking apparatus according to the present invention.

FIG. 2 is a schematic side view showing a laminating step portion of an example of the same ceramic green sheet laminating apparatus, and is a state before a ceramic green sheet held on a lower surface of an upper die is overlaid inside a lower die.

FIG. 3 is a schematic side view showing a laminating step portion of an example of the same ceramic green sheet laminating apparatus, which is a state before a ceramic green sheet held on a lower surface of an upper die is overlaid inside a lower die.

FIG. 4 is a schematic plan view showing a state in which a monolithic ceramic capacitor obtained by using the same ceramic green sheet laminating apparatus is cut in a direction orthogonal to the internal electrodes.

FIG. 5: 1/4 of a monolithic ceramic capacitor as an example of a component made by laminating ceramic green sheets
FIG. 3 is a perspective view showing an internal structure and an external appearance by cutting a part.

FIG. 6 is a vertical cross-sectional side view exaggerating distortion of a laminated body of ceramic green sheets for obtaining a laminated body of the same laminated ceramic capacitor.

FIG. 7 is an exploded perspective view showing separated layers of a laminated body of a laminated ceramic capacitor as an example of a component made by laminating ceramic green sheets.

FIG. 8 is a perspective view in which each layer of the laminated body of the ceramic green sheets for obtaining the laminated body of the laminated ceramic capacitor is shown separately.

[Explanation of symbols]

11 careers 12 Upper mold 22 Lower mold 32 exhaust passage 35 vacuum pump b Ceramic green sheet

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Claims (5)

(57) [Claims] 1. A ceramic green sheet laminating apparatus for stacking a plurality of ceramic green sheets (b) and pressing the ceramic green sheets (b) in the laminating direction by pressure to hold the ceramic green sheets (b). , A carrier (11) for carrying,
A lower mold (22) having a concave portion for receiving the ceramic green sheets (b) supplied from the carrier (11) and sequentially stacking the ceramic green sheets (b).
An upper die (12) for pressing the ceramic green sheet (b) laminated inside the lower die (22) and a lower die (2) for laminating the ceramic green sheet (b).
Exhaust passage (32) that opens above and below the side surface of the recess of 2)
A ceramic green sheet laminating apparatus, comprising: a pressure reducing unit that exhausts the gas through the chamber to reduce the pressure in the recess to a negative pressure. 2. The lower mold (22) has a recess for receiving the laminated ceramic green sheets (a), and the depressurizing means exhausts air in the recess to create a negative pressure in the recess. ceramic green sheet laminating apparatus according to claim 1, characterized in that the. 3. The upper mold (12) is a ceramic green sheet laminating apparatus according to claim 1 or 2, characterized in that it also serves as a carrier (11) for conveying the ceramic green sheet (b). 4. A ceramic green sheet laminating method in which a plurality of ceramic green sheets (b) are stacked and these ceramic green sheets (b) are pressed and pressed against each other in the laminating direction. transported to the lower mold (22) and held in the recess of the lower mold (22), sequentially with laminated supplied ceramic green sheet (b), Se
Lamic green sheet (b) is laminated one or more
Each time it is, the opening and below the side face of the recess of the lower mold (22)
The ceramic green sheets (b) are laminated by exhausting the exhaust gas through the exhaust passage (32) and applying a negative pressure in the recess.
A method for laminating a ceramic green sheet, characterized in that: is pressed by an upper mold (12). 5. The ceramic green sheet (b) comprises 1
Every time 60 to 60 sheets are stacked, the lower die (22) and the upper die (1
Ceramic green sheet laminating method according to claim 5, characterized in that it is pressed between the 2).