JP4371261B2 - Ceramic green sheet crimping device - Google Patents

Description

  The present invention relates to a ceramic green sheet crimping apparatus used for manufacturing other multilayer ceramic electronic components such as multilayer capacitors and multilayer inductors.

  In ceramic electronic components, for example, a multilayer ceramic capacitor has been conventionally manufactured by the following method. That is, a ceramic coating containing ceramic powder, organic binder, plasticizer, solvent, etc. is formed into a sheet shape on the support by the doctor blade method, etc., and internal electrodes such as palladium, copper, nickel are screen printed on it. To form. The sheet-like molded product is generally called a ceramic green sheet.

  Next, this ceramic green sheet is cut into a predetermined size, and is laminated and laminated. The laminated ceramic green sheets are pressed by a press to form an integrated block ceramic green sheet laminate.

  The ceramic green sheet laminate is cut to a predetermined size to form a ceramic green chip. The ceramic green chip obtained in this way is burned out with an internal binder and fired in a temperature range of 1000 to 1400 ° C. The obtained fired body becomes a multilayer ceramic capacitor by forming terminal electrodes of silver, silver-palladium, nickel, copper or the like.

  In such a manufacturing process of a ceramic electronic component typified by a multilayer ceramic capacitor, the ceramic green sheet stacking and crimping processes are disclosed in, for example, Patent Documents 1 to 4 and the like. Specifically, Patent Document 1 discloses a method in which a through hole is provided in a ceramic green sheet, and further, suction holes are provided in upper and lower molds, and suction is performed through the through hole, and laminated pressure bonding is performed while holding the ceramic green sheet. Is disclosed. Patent Documents 2 to 4 disclose a method in which suction holes are provided in upper and lower molds, sucked through the through holes, and laminated and pressure-bonded.

  By the way, in recent years, downsizing of electronic devices and high density mounting of circuit components have progressed, and in the field of multilayer ceramic electronic components such as multilayer ceramic capacitors, miniaturization and high performance are desired.

  As a method for reducing the size and increasing the capacity of a multilayer ceramic capacitor, there are a method of making a dielectric layer and an internal electrode layer thinner and multilayered. In order to reduce the thickness of the dielectric layer and internal electrode layer, it is necessary to make the ceramic green sheet before firing thin. At present, a dielectric layer with a thickness of 1 μm and an internal electrode layer with a thickness of 1.2 μm have been realized. Has been.

  However, as the dielectric layer and internal electrode layer are made thinner, it has been found that the following problems arise in the vacuum adsorption method.

  The ceramic green sheet or the laminate thereof is in a stage before firing and has flexibility. In the case of the vacuum suction method, a suction hole is provided in the upper and lower molds, and suction is performed through the through hole. For this reason, the ceramic green sheet or its laminated body arrange | positioned on a metal mold | die deform | transforms into uneven | corrugated shape by a contact surface being attracted | sucked by the micro recessed part of the suction hole of a metal mold | die.

The uneven deformation becomes more conspicuous in the pressure-bonding process in which the ceramic green sheet is heated and pressed, and the more the ceramic green sheet becomes thinner, the more adverse the effect. Further, the uneven deformation causes distortion of the entire ceramic green sheet, causes a stacking shift and an internal electrode pattern shift, and causes a structural defect in which the density of the ceramic green sheet stack is not uniform. This structural defect causes delamination (delamination) and cracks, and causes a short circuit failure and a withstand voltage failure in the multilayer ceramic capacitor after the ceramic green sheet laminate is fired.
JP 2001-102248 A Japanese Patent Laid-Open No. 11-277518 Japanese Patent No. 2504276 JP-A-10-71611

  An object of the present invention is to provide a ceramic green sheet crimping apparatus that does not cause distortion in the entire ceramic green sheet and does not cause structural defects in which the density of the ceramic green sheet laminate is not uniform.

  Another object of the present invention is to provide a ceramic green sheet crimping apparatus that can suppress the occurrence of delamination and cracks and prevent short circuit failure and withstand voltage failure in a fired multilayer ceramic capacitor.

  In order to solve the above-described problems, a ceramic green sheet crimping apparatus according to the present invention includes a first mold, a second mold, a pressurizing unit, and an electrostatic adsorption unit, and is laminated. Crimp the. The first mold includes a receiving surface. The second mold includes a pressure surface, and the pressure surface faces the receiving surface. The pressurizing means drives the first mold or the second mold to relatively approach or move the pressurizing surface and the receiving surface relatively close to each other.

  The electrostatic attraction means includes a charging electrode and an electrostatic charging member, and is provided in the first mold. The electrostatic charging member is combined with the charging electrode, and has a smooth surface to form the receiving surface. The receiving surface electrostatically attracts the ceramic green sheet.

  As described above, in the ceramic green sheet crimping apparatus according to the present invention, the second die includes the pressing surface, and the pressing surface is opposed to the receiving surface of the first die. The pressurizing means drives the second mold to bring the pressing surface closer to or away from the receiving surface. For this reason, a ceramic green sheet can be arrange | positioned and laminated | stacked on a receiving surface in the state which the receiving surface and the pressurization surface have separated.

  Here, the ceramic green sheet crimping apparatus according to the present invention includes electrostatic adsorption means. The electrostatic adsorption means includes a charging electrode and an electrostatic charging member, and is provided in the first mold. The electrostatic charging member is combined with a charging electrode, and the surface forms a receiving surface. The receiving surface electrostatically adsorbs the ceramic green sheet. Therefore, unlike the conventional vacuum suction, the receiving surface can be a smooth surface without unevenness, and the ceramic green sheet can be arranged on the smooth receiving surface and sucked.

  As described above, since the receiving surface has a smooth surface, the ceramic green sheet held on the receiving surface is not deformed unevenly. For this reason, distortion does not occur in the entire ceramic green sheet even in a laminated state before pressure bonding.

  After the ceramic green sheet is disposed on the receiving surface as described above, the second mold is driven by the pressing means to bring the pressing surface close to the receiving surface, thereby the ceramic green sheet is A pressure is applied between the receiving surface and the pressure surface and pressure bonding is performed to obtain an integrated ceramic green sheet laminate.

  Here, the ceramic green sheet crimping apparatus according to the present invention includes electrostatic adsorption means, and the receiving surface is formed on a smooth surface. Irregular deformation does not occur in the ceramic green sheet. For this reason, even after pressure bonding, the entire ceramic green sheet is not distorted, it is possible to prevent laminating deviation and internal electrode pattern deviation, and structural defects that cause uneven density of the ceramic green sheet laminate are not caused. . Therefore, it is possible to suppress the occurrence of delamination and cracks and prevent short circuit failure and withstand voltage failure in the fired multilayer ceramic capacitor.

  Specifically, the receiving surface can be made of alumina. The flatness is preferably 50 nm or less. Such flatness can be easily realized with alumina.

As described above, according to the present invention, the following effects can be obtained.
(A) It is possible to provide a ceramic green sheet pressure bonding apparatus that does not cause distortion in the entire ceramic green sheet and does not cause structural defects in which the density of the ceramic green sheet laminate is not uniform.
(B) It is possible to provide a ceramic green sheet pressure bonding apparatus that can suppress the occurrence of delamination and cracks and prevent short circuit failure and breakdown voltage failure in the fired multilayer ceramic capacitor.

  Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. However, the attached drawings are merely examples.

  FIG. 1 is a front view of a ceramic green sheet crimping apparatus according to the present invention. The illustrated crimping apparatus includes a first mold 1, a second mold 2, a pressurizing unit 3, an electrostatic adsorption unit 4, and supports 51 and 52.

  The first mold 1 is fixed to a mounting base 6 and includes a heater 13 and a receiving base 11. The cradle 11 includes a receiving surface 12, and the ceramic green sheet 8 is disposed on the receiving surface 12. The ceramic green sheet 8 is a soft sheet before firing. Generally, a plurality of layers are stacked to form a stacked body.

  The second mold 2 includes a pressurizing surface 21 and a heater 23, and is arranged so that the pressurizing surface 21 faces the receiving surface 12. Both sides are supported by support bodies 51 and 52. It is slidably supported along. The supports 51 and 52 are fixed to the mounting base 6.

  The pressurizing means 3 is driven by a driving device (not shown), and slides the second mold 2 along the supports 51 and 52 so that the pressurizing surface 21 approaches the receiving surface 12 by F1 or separation F2. And the pressurization surface 21 is made to approach the receiving surface 12, and the ceramic green sheet 8 arrange | positioned on the receiving surface 12 is crimped | bonded. As the driving device, a pneumatic driving device, a hydraulic driving device, a motor, or the like can be used. From the viewpoint of minute operation control, a motor is desirable.

  In the present embodiment, the first mold 1 is configured as a fixed mold, and the second mold 2 is configured as a movable mold. However, if the receiving surface 12 and the pressing surface 21 can be relatively approached and separated from each other. The fixed type and the movable type may be interchanged.

  The electrostatic attraction means 4 includes a charging electrode 41, a power source 42, and an electrostatic charging member 43, and is fixed to the cradle 11 of the first mold 1. The charging electrode 41 is connected to, for example, the positive potential side of the power source 42.

  In the figure, a DC power source is shown as the power source 42 for simplification of explanation, but an AC power source may be used. Further, the charging electrode 41 may be plural, and AC power sources having different phases may be supplied to each of the charging electrodes 41. Conventional techniques can be applied to these specific configurations.

  The electrostatic charging member 43 is made of an insulating material and is combined with the charging electrode 41 to form the receiving surface 12 with a smooth surface. The receiving surface 12 electrostatically attracts the ceramic green sheet 8.

  FIG. 2 is a conceptual diagram showing the electrostatic state of the electrostatic attracting means and the adsorbed ceramic green sheet. As shown in FIG. 2, the charging electrode 41 is connected to the positive potential side of the power source 42 and is positively charged. The electrostatic charging member 43 combined with the charging electrode 41 is polarized, negative electricity is induced on the charging electrode 41 side, and the opposite side far from the charging electrode 41 is positively charged. The positively charged surface of the electrostatic charging member 43 constitutes the receiving surface 12.

  Negative electricity is induced to the receiving surface 12 side of the ceramic green sheet 8 disposed on the receiving surface 12, and the ceramic green sheet 8 is electrostatically adsorbed by the positive electricity of the receiving surface 12. Since the surface of the electrostatic charging member 43 constituting the receiving surface 12 is formed smoothly, the ceramic green sheet 8 disposed on and held by the receiving surface 12 does not undergo uneven deformation.

  The shape of the electrostatic charging member 43 may be a shape having a larger plane than the shape of the ceramic green sheet 8 to be arranged, and is formed in, for example, a quadrangular shape considering the shape. A combination form of the charging electrode 41 and the electrostatic charging member 43 includes a form in which the flat electrostatic charging member 43 is disposed in contact with the charging electrode 41, or an insulating coating is applied to the charging electrode 41, and the insulating coating is combined with the electrostatic charging member 43. Or a form in which the charging electrode 41 is built in the electrostatic charging member 43 as an internal electrode. The material of the electrostatic charging member 43 is suitably a ceramic material such as alumina. If it is an alumina, it can respond to the above-mentioned various forms, has high durability against heating and pressurization, and the surface flatness can be reduced to 50 nm or less.

  FIG. 3 shows a state in which the receiving surface 12 and the pressing surface are brought close to each other in the ceramic green sheet pressure bonding apparatus according to the present invention. After the ceramic green sheet 8 is disposed on the receiving surface 12, the second mold 2 is driven by the pressing means 3 to bring the pressing surface 21 closer to the receiving surface 12, thereby the ceramic green sheet 8. Are pressed and pressure-bonded between the receiving surface 12 and the pressure surface 21 to obtain an integrated ceramic green sheet 8 laminate.

  FIG. 4 is a view showing the relationship between the receiving surface 12 and the ceramic green sheet 8 in the ceramic green sheet crimping apparatus according to the present invention.

  Since the ceramic green sheet crimping apparatus according to the present invention includes electrostatic adsorption means and the receiving surface 12 is formed with a smooth surface, the ceramic held on the receiving surface 12 in the process of pressure bonding. Unevenness deformation does not occur in the green sheet 8.

  For this reason, even after the pressure bonding, the entire ceramic green sheet 8 is not distorted, and it is possible to prevent misalignment and internal electrode pattern displacement, resulting in a structural defect in which the density of the laminate of the ceramic green sheet 8 becomes uneven. There is nothing. Therefore, it is possible to suppress the occurrence of delamination and cracks and prevent short circuit failure and withstand voltage failure in the fired multilayer ceramic capacitor.

  FIG. 5 is a diagram showing a problem in the case of using conventional vacuum suction having a porous receiving surface. As shown in FIG. 5, the vacuum suction method is a method of sucking the ceramic green sheet 8 disposed on the cradle 44 by vacuum suction using a porous cradle 44 including a large number of minute openings. .

  The ceramic green sheet 8 is in a stage before firing and has flexibility. The surface of the porous pedestal 44 forms an uneven surface 441 with a large number of openings 442. For this reason, the ceramic green sheet 8 disposed on the cradle 44 is deformed into a concavo-convex shape with the contact surface with the porous cradle 44 being attracted to the concavo-convex surface 441 by the opening 442.

  The uneven deformation becomes more conspicuous in the pressure-bonding process in which the ceramic green sheet 8 is heated and pressed, and the more the ceramic green sheet 8 is made thinner, the more adverse the effect is.

  Furthermore, the uneven deformation causes distortion of the entire ceramic green sheet 8, which causes misalignment and internal electrode pattern misalignment, and causes a structural defect in which the density of the laminate of the ceramic green sheet 8 is not uniform. Conventionally, this structural defect causes a short circuit failure and a withstand voltage failure in the multilayer ceramic capacitor after the multilayer body of ceramic green sheets 8 is fired, causing delamination (delamination) and cracks. is there. It is clear from the above description that the structural defect can be avoided by the ceramic grease sheet crimping apparatus according to the present invention.

  The ceramic green sheet crimping apparatus according to the present invention can be widely applied to the manufacture of multilayer electronic components that require a plurality of ceramic green sheets to be laminated and crimped. Hereinafter, as a typical example, the production of a multilayer ceramic capacitor will be described as an example.

  FIG. 6 is a plan view of the ceramic green sheet 8 used for manufacturing the multilayer ceramic capacitor, and FIG. 7 is a diagram for explaining a laminated state of the ceramic green sheet 8 shown in FIG.

  As shown in FIG. 6, the ceramic green sheet 8 is obtained by forming electrodes E11 to Emn in a matrix of m rows and n columns on a ceramic coating layer 80. The illustrated electrodes E11 to Emn have a planar shape that is longer in the horizontal direction X than in the vertical direction Y. The ceramic paint layer 80 and the electrodes E11 to Emn are in a state after drying. Such a ceramic green sheet 8 can be obtained according to a known technique. The ceramic green sheets 8 are produced by the number n of stacked layers. The produced ceramic green sheets 81 to 8n are not shown in the figure, but are held by a carrier having a positioning function provided separately, and are sequentially carried to the crimping apparatus.

  The first ceramic green sheet 81 illustrated in FIG. 6 is disposed on the receiving surface 12 of the crimping apparatus in a state where the receiving surface 12 and the pressing surface 21 illustrated in FIG. 1 are separated from each other. Since the surface of the electrostatic charging member 43 that constitutes the receiving surface 12 is positively charged, the ceramic green sheet 81 that is to be arranged is induced to negative electricity opposite to the receiving surface 12 on the receiving surface 12 side. It is electrostatically attracted to the receiving surface 12.

  The second ceramic green sheet 82 is positioned and laminated with an offset ΔX in the lateral direction X with respect to the first ceramic green sheet 81. The same positive electricity as that of the receiving surface 12 is induced on the side of the first ceramic green sheet 81 far from the receiving surface 12, and the second ceramic green sheet 82 has a first ceramic green sheet on the laminated side. Negative electricity opposite to that of the sheet 81 is induced and electrostatically adsorbed to the first ceramic green sheet 81.

  The third ceramic green sheet 83 is positioned and laminated at the same position in the plane direction as the first ceramic green sheet 81. The same positive electricity as that of the receiving surface 12 is induced on the side of the second ceramic green sheet 82 far from the receiving surface 12, and the third ceramic green sheet 83 has a second ceramic green sheet on the laminated side. Negative electricity opposite to the sheet 82 is induced and electrostatically adsorbed to the second ceramic green sheet 82.

  The fourth and subsequent ceramic green sheets 8 (not shown) are similarly offset alternately and similarly electrostatically adsorbed. The ceramic green sheets 81 to 8 n held on the receiving surface 12 are heated by the heater 13.

  In the electrode printing process of the ceramic green sheet 8, it is possible to employ a process in which two plate makings are used to produce two types of ceramic green sheets 8 with electrodes offset, and these are alternately laminated. The ceramic green sheets 8 to be laminated need not have the offset described above.

  After laminating a predetermined number n of ceramic green sheets 81 to 8n, as shown in FIG. 3, the second die 2 is driven in the direction of arrow F1 by the pressurizing means 3, and the pressurizing surface 21 is received. Approach in the direction of surface 12. As a result, the ceramic green sheets 81 to 8 n are pressed while being heated by the heaters 13 and 23. The laminated body 9 of the ceramic green sheets 8 that are pressure-bonded is integrated into a block shape.

  Here, the receiving surface 12 has a smooth surface. For this reason, since the laminated body 9 of the ceramic green sheet 8 made into a thin layer and a multilayer can be uniformly loaded, the laminated body 9 of the ceramic green sheet 8 is not deformed unevenly. Therefore, distortion does not occur in the entire laminated body 9 of the ceramic green sheets 8, and it is possible to prevent misalignment and internal electrode pattern displacement, thereby preventing structural defects that cause uneven density.

  Thereafter, the laminate 9 of the ceramic green sheets 8 is cut into a predetermined size to form a ceramic green chip. The ceramic green chip obtained in this way is burned out with an internal binder and fired in a temperature range of 1000 to 1400 ° C. The obtained fired body becomes a multilayer ceramic capacitor by forming terminal electrodes of silver, silver-palladium, nickel, copper or the like.

  Since the laminate of the ceramic green sheet 8 manufactured using the crimping apparatus of the present invention has no structural defects, it can suppress the occurrence of delamination and cracks, and can prevent a short circuit failure and a withstand voltage failure in the fired multilayer ceramic capacitor. .

  The present invention has been described in detail with reference to the preferred embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made by those skilled in the art based on the basic technical idea and teachings. It is self-evident that

It is a front fragmentary sectional view of the ceramic green sheet crimping | bonding apparatus which concerns on this invention. It is a conceptual diagram which shows the electrostatic state of an electrostatic adsorption means and the adsorbed ceramic green sheet. It is a front fragmentary sectional view at the time of the crimping | compression-bonding operation | movement of the ceramic green sheet crimping | bonding apparatus which concerns on this invention shown in FIG. It is a figure which shows the relationship between the receiving surface and the ceramic green sheet in the ceramic green sheet crimping | bonding apparatus which concerns on this invention. It is a figure which shows the problem at the time of using the conventional vacuum suction which has a porous receiving surface. It is a top view of the ceramic green sheet used for manufacture of a multilayer ceramic capacitor. It is a figure explaining the lamination | stacking state of the ceramic green sheet shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st type | mold 12 Reception surface 2 2nd type | mold 21 Pressurization surface 3 Pressurization means 4 Electrostatic adsorption means 41 Charging electrode 43 Electrostatic charging member 8, 81-8n Ceramic green sheet

Claims (3)

An apparatus that includes a first mold, a second mold, a pressurizing unit, and an electrostatic adsorption unit, and crimps the laminated ceramic green sheets,
The first mold includes a receiving surface;
The second mold includes a pressing surface, and the pressing surface is opposed to the receiving surface,
The pressurizing means drives the first mold or the second mold, relatively moves the pressurizing surface and the receiving surface closer to or away from each other,
The electrostatic adsorption means includes a charging electrode and an electrostatic charging member, and is provided in the first mold.
The electrostatic charging member is combined with the charging electrode, the surface is formed smoothly and constitutes the receiving surface,
The ceramic green sheet pressure bonding apparatus, wherein the receiving surface electrostatically attracts the ceramic green sheet.   It is the crimping | compression-bonding apparatus described in Claim 1, Comprising: The said receiving surface is a ceramic green sheet crimping | compression-bonding apparatus comprised with an alumina.   3. The ceramic green sheet pressure bonding apparatus according to claim 1, wherein the receiving surface has a flatness of 50 nm or less. 4.

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