JP2009117458A - Laminated ceramic electronic component, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make higher lamination possible, suppress defects including crack, reduce short-circuit failures, and improve reliability by forming an inside electrode and a dielectric layer to be thin and uniform in the processes of forming and transferring the inside electrode and the dielectric layer of an electronic component such as a laminated ceramic capacitor. <P>SOLUTION: A fine and highly precise electrode pattern and the thin dielectric layer can be formed in a relatively easy manner by using a heat transfer technique with thermal heads. Transfer is performed by using at least two thermal heads. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a conductive paste widely used in various electric products such as a mobile phone, an electronic tuner for a television passive device, and a liquid crystal television, and a method for manufacturing a ceramic electronic component using the conductive paste. It mainly relates to the manufacturing method of multilayer ceramic electronic components represented by multilayer ceramic capacitors, multilayer varistors, multilayer piezoelectric elements, multilayer chip inductors, etc. Especially, thermal transfer of internal electrode layer and dielectric layer in ceramic green sheet dielectric The present invention relates to a method for manufacturing a laminated ceramic electronic component which is characterized by being formed by a construction method.

  A multilayer capacitor or multilayer piezoelectric body, which is a multilayer ceramic electronic component, is formed by alternately laminating internal electrodes and dielectrics, and laminating (thermocompression bonding) the formed multilayer body, followed by firing. Composed. FIG. 1 shows a multilayer ceramic capacitor as a representative example of a ceramic electronic component. In FIG. 1, a typical example of such a conventional multilayer electronic component in which 1 is a dielectric ceramic layer, 2 is an internal electrode layer, and 3 is an external electrode will be described below.

  Among ceramic electronic components, for example, a multilayer ceramic capacitor is constituted by a ceramic element body that is obtained by alternately laminating the dielectric layers and the electrode layers. Here, the internal electrode layers are alternately taken out on one outer surface and the other outer surface of the ceramic body, and terminal electrodes for external connection are formed from the upper portions of these take-out portions.

  A conventional method for manufacturing a multilayer ceramic capacitor is to first make a slurry by adding polyvinyl butyral as a binder component, benzyl butyl phthalate as a plasticizer component, and butyl acetate as a solvent component to a dielectric material powder such as barium titanate. The slurry is applied and dried on a base film such as PET using a post doctor blade method, a calender roll method or the like, and a ceramic green sheet for dielectric ceramic 1 having a thickness of 5 to 50 μm is formed.

  Separately, a plurality of internal electrode layers 2 having a thickness of 2 to 4 μm are juxtaposed on a base film such as PET by a printing method using a conductive paste mainly composed of nickel. If the thickness of the internal electrode layer 2 is small, the internal electrode layer 2 contracts during the subsequent firing of the multilayer ceramic capacitor and becomes partially discontinuous, which may cause a decrease in capacitance. It is necessary to apply 2μm or more.

  Next, the internal electrode layer 2 coated on the base film surface is thermally transferred to the ceramic green sheet surface. A plurality of ceramic green sheets subjected to thermal transfer are laminated and pressed to form a ceramic green block laminate (not shown). The lamination of the ceramic green sheets is carried out by shifting a predetermined dimension in the longitudinal direction of the internal electrode layer 2 that is alternately transferred for each layer.

  Next, the laminated green block is cut into predetermined dimensions, and then fired under predetermined conditions to produce a sintered body. The sintered body has a structure in which internal electrode layers 2 are exposed on opposite end faces opposite to each other across the dielectric ceramic layer 1 on both end faces in the longitudinal direction.

  An outer electrode 3 is provided on the end surface of the obtained sintered body where the internal electrode layer 2 is exposed to complete a multilayer ceramic capacitor. For example, the method is disclosed in Japanese Patent Publication No. 5-25811.

  However, in the structure in which internal electrode portions are formed and stacked on the green dielectric layer, a space is formed between adjacent internal electrode portions during stacking. When the laminate is constructed and fired, the space near the external electrode is compressed and fired, so the internal electrodes are not arranged in the same plane and are curved at the end, and the end and the center thereof There is a step between them.

  Further, due to the thickness of the internal electrode, as the stacking progresses in a higher order, significant unevenness is generated in the laminated molded body including the internal electrode and its peripheral portion. At this time, a portion not including the internal electrode becomes a concave portion, and it is difficult to sufficiently apply pressure at the time of lamination. Structural defects such as cracks and delamination occur in this portion of the laminated molded body and the element after firing.

  Furthermore, in recent years, multilayer ceramic electronic components tend to be smaller and have higher capacity. Therefore, when the dielectric layer is made thinner, the dielectric layer is likely to be cut at the stepped portion, which causes problems such as a short circuit between the internal electrodes.

As measures for these improvements, a thermal transfer method in which the electrode thickness is made much thinner than in the screen printing method and the electrode is formed by a dry method, and an invention for improving the accuracy of the internal electrode has been made (for example, JP-A 64-42809) (See Japanese Patent Publication No. 3-108709).
Japanese Patent Publication No.5-25381 JP-A 64-42809 Japanese Patent Laid-Open No. 3-108709

  Under the influence of downsizing and weight reduction for devices in which multilayer ceramic electronic components are used, there is a demand for downsizing as in the case of devices. However, many problems arise when manufacturing a small-sized and large-capacity capacitor as currently required using the conventional method for manufacturing a multilayer electronic component as described above. For example, it is necessary to reduce the thickness of each layer of laminated ceramic electronic components. However, due to productivity and structural problems, many problems such as short circuit between internal electrodes may occur in reliability. Is expensive.

  The screen printing method is conductive by point contact of conductive particles, and if the resistance value of the internal electrode increases, the conductivity becomes uncertain and there is a problem in the reliability of the parts, and the recent thinning and miniaturization of electronic parts However, there is a disadvantage that the thickness of the internal electrode becomes 1 μm or more.

  In addition, since the green sheet is rubbed against the screen with a squeegee, the forming method has a drawback that when the green sheet becomes thin, the sheet is stressed, and the sheet is torn or deformed.

  Furthermore, the method of forming a metal film on a base film by a thin film formation method such as vapor deposition or sputtering has disadvantages such as an increase in the number of vapor deposition processes, the number of processes, and low productivity.

  Accordingly, it is an object of the present invention to provide a multilayer ceramic electronic component that is small in size, highly reliable, and can be easily manufactured, and a method for manufacturing the multilayer ceramic electronic component.

In order to solve the above problems, the present invention provides a ceramic green in which internal electrode layers and ceramic dielectric layers are uniformly held and formed on a base film in a method of manufacturing a ceramic electronic component in which alternating layers are laminated. A process of pressing a sheet and an internal electrode sheet formed by applying a conductive paste on another base film so that the ceramic green sheet and the internal electrode sheet face each other, and a heat generation position are selectively controlled. Using multiple thermal heads that can move the multiple heads relative to the base film, and input the required electrical signals corresponding to the transfer pattern, and heat from the head heat generating part will generate the internal heat from the transfer film. The electrode pattern is thermally transferred, and the dielectric portion and the dielectric layer are transferred from the film using another thermal head. In the multilayer ceramic electronic component, the internal electrode layer includes a step in which dielectric portions are continuously arranged in the same plane, and the steps described above are repeated to form a laminate, and an external electrode is formed. It is a manufacturing method.
In order to carry out the above method, in the heat transferable material for forming the internal electrode layer and the dielectric layer, at least the internal electrode layer includes a wax, a conductive metal powder, and a polymer. The dielectric layer includes at least a wax, dielectric particles, and a polymer. As the polymer, polymers having different glass transition points Tg are applied, and are shifted at least by about 20 ° C. to 50 ° C. However, the softening point is preferably lower, and the relative hardness is controlled between the internal electrode layer and the dielectric layer without depending on the adjustment of a plasticizer or the like. The internal electrode layers and the ceramic dielectric layers are alternately laminated, and the ceramic layers are disposed on the laminate so that relatively hard layers and soft layers are alternately arranged, and heating and pressurizing are performed. A multilayer ceramic electronic component comprising a step of transferring a green sheet or an electrode layer onto the laminate. In the step of transferring the internal electrode layer onto the ceramic green sheet, the electrode layer may be transferred onto a pre-formed ceramic green sheet, or the ceramic green sheet may be formed on the base film and peeled off on the base film. At this stage, the electrode layer may be transferred onto the ceramic green sheet.

  The present invention solves the above-mentioned conventional problems. According to the invention according to claim 1 of the present invention, the thermal head is composed of a conductor (electrode) layer / dielectric layer and separate ones. It is no longer necessary to align the softening points. However, a lower softening point is preferred. And consumption of heating elements, such as a thermal head, can be controlled. For this reason, cost reduction becomes possible. Furthermore, by using separate heads in the transfer of the (electrode) layer / dielectric layer, the temperature of each head is stabilized and the transfer residue can be prevented.

  Further, according to the invention of claim 2, it is possible to control the hardness of the conductor (electrode) layer / dielectric layer by deliberately shifting the glass transition point Tg by 20 ° C. to 50 ° C. For example, when the dielectric layer is thin, the conductor layer is softened. That is, since the hard layer and the soft layer are alternately laminated, adhesion at the time of lamination is improved. This has a positive effect on planarization. If the dielectric layer is thick, the reverse may be effective. Furthermore, the merit of changing the hardness without depending on the plasticizer is caused by using a plurality of heads such as twin heads.

A method for manufacturing a multilayer ceramic capacitor by a thermal transfer method using a thermal head according to an embodiment of the present invention will be described.
(Example 1)
First, a PET film (ER106T Fujicopian) is prepared as a transfer medium, printed so that the film thickness is about 1.9 μm, and 8 parts by weight of IBMA (manufactured by Sekisui Chemical) as a binder and 4 parts by weight of styrene resin. , A patterned screen plate used to print and mold a conventional internal electrode layer using a vehicle in which 1 to 10% by weight of carbana wax is dissolved in 88 parts by weight of α-terpineol (Kanto Kagaku Grade 1) Printing was performed using an α-25 mesh and dried at 110 ° C. for 7 minutes. FIG. 1 is a schematic cross-sectional view of a laminate in this example. In FIG. 2, 6 is a PET film as a transfer medium, and 5 is an electrode layer containing nickel paste, thermoplastic resin, and the like.

  Next, a ceramic green sheet 13 (see FIG. 4) containing a dielectric ceramic powder (average particle diameter of 1 μm) formed on the PET film 6 is prepared, and the ceramic dielectric layer 10 which is the lower ineffective layer as in the conventional method. The electrode layer 5 formed on the previously prepared PET film 6 is faced as shown in FIG. 3 and heated and heated at 115 ° C. and 3 kgf / cm 2 for about 5 seconds by the thermal head 1. Pressure was applied to transfer only the desired pattern portion.

  Further, as shown in the cross-sectional views of the dielectric laminates of FIGS. 4 and 5, the ceramic green sheet 13 was opposed to transfer the dielectric layer. On top of that, the electrode layer 9 and the dielectric ceramic layer 13 are alternately transferred repeatedly until the effective layer becomes 150 layers, and the upper ineffective layer is laminated thereon as in the conventional method. A ceramic green chip was obtained by cutting. The ceramic green chip thus obtained was degreased at 400 ° C. for 4 hours and baked at 1280 ° C. for 2 hours in the same manner as in the conventional method to form external electrodes to obtain a multilayer ceramic capacitor.

  As a result, a 1608 type chip capacitor body was obtained. An internal analysis was performed on each of the obtained 100 chip-type multilayer capacitor bodies. As a result, there were no defects such as delamination and cracks.

  In addition, the nickel paste in Example 1 has no problem even with other commercially available pastes or in-house manufactured pastes, and α-terpineol, BLS, and BBP are each a butyral resin having a different degree of polymerization or a high thermoplasticity. Any other plasticizer such as resin, DOA, DOP, DBP, and any solvent compatible with the used resin may be used as long as there is no problem in printability.

(Example 2)
Conductive powder is prepared with a blending ratio of 85 parts by weight of nickel metal powder and 15 parts by weight of barium titanate powder, and consists of a copolymer of 50% by weight of conductive powder and a polymerization ratio of isobutyl methacrylate and acrylic acid of 90: 1. (Meth) acrylic acid alkyl ester polymer 2% by weight, carbana wax was blended so as to have a solid content of 50% by mixing 1 to 25% by weight of toluene 70 / methyl ethyl ketone 30 to form a slurry.

  The conductive metal powder is used to form a conductor film. The conductive metal powder material is considered to be preferably 80% by weight or less from the viewpoint of transferability and uniformity of the ink layer thickness. If the conductive metal exceeds 80% by weight, it is considered difficult to form a thin and uniform ink layer on a carrier film or the like. This slurry was formed on a carrier film having a thickness of 5 μm so as to have a thickness of 1 μm after firing, and then dried to prepare a thermal transfer sheet.

  Next, 100 parts by weight of barium titanate powder, 8 parts by weight of polyvinyl butyral resin, and 4 parts by weight of dibutyl phthalate were blended to a solid content of 45% under a toluene 60 / ethanol 40 mixture to form a dielectric slurry. Create a ceramic green sheet on the mold release surface of the carrier film coated on the surface with a silicone mold release agent so that the thickness after firing by the doctor blade method using the slurry is 3μ, This was wound up on a roll.

  Similarly to the above, a ceramic green sheet was formed so that the thickness of the surface treated with a silicone-based mold release agent was 10 μm, and this was wound up into a roll shape to obtain a sheet of upper and lower ineffective layers.

  In addition, a support attached to the pet film with adhesive is prepared, and a sheet for the lower ineffective layer having a thickness of 80 μm after firing of the ceramic green sheet that has already been cut into the pet film surface, The ceramic green sheets were placed so as to face the pet film surface, and heat-pressed under the conditions of a temperature of 80 ° C. and a pressure of 4 kgf / cm 2 from the sheet carrier film (38 μm thick pet film).

  Further, as shown in FIG. 7, the thermal transfer ink layer side of the thermal transfer sheet is placed on the lower invalid layer sheet of the support, the thermal head 1 is brought into contact with the carrier film surface of the thermal transfer sheet, and the thermal head The thermal transfer ink layer was heated and pressurized by 1 to peel off the carrier film and transfer the conductor film. In the same procedure, transfer the dielectric film using another thermal head 2, 3 etc. (see Fig. 8) and repeat the transfer of the electrode layer and dielectric ceramic layer alternately to make the effective layer 270 layers. Do until.

The prepared laminate was subjected to isostatic pressing. This treatment was performed by encapsulating the laminate with a nylon bag (not shown), vacuum-packing it, placing it in a hydrostatic pressure machine (not shown), and applying 100 kgf / cm 2 pressure in 70 ° C. water.
The laminate subjected to the isostatic pressing was cut into a multilayer ceramic capacitor body. After removing the binder from this element body, it was held at 1300 ° C. for 2 hours in a reducing atmosphere and further annealed to obtain a 1005 type chip capacitor element body.

  In the present embodiment, the electrode layer and the dielectric ceramic layer can be peeled off without causing any problem in the construction method even if other adhesive tapes are used.

  As a result of internal analysis of 50 chip bodies of the obtained chip type multilayer ceramic capacitor, one crack defect and one pinhole defect occurred.

  This is considered to be caused by the occurrence of a sheet attack in which the organic solvent of the conductive paste is transferred to the ceramic green sheet.

  Therefore, the sheet attack can be controlled or eliminated by slightly reducing the amount of the organic solvent or by transferring the heat transfer ink layer after drying without containing the solvent.

    The present invention mainly relates to a method for manufacturing a multilayer ceramic electronic component typified by a multilayer ceramic capacitor, a multilayer varistor, a multilayer piezoelectric element, a multilayer chip inductor, and the like, and more particularly, an internal electrode layer and a dielectric in a ceramic green sheet dielectric The present invention relates to a method of manufacturing a laminated ceramic electronic component which is characterized by forming a layer by a thermal transfer method, and is widely used in various electric products such as a mobile phone, an electronic tuner of a television passive device, and a liquid crystal television.

It is the schematic sectional drawing which illustrated transfer lamination. It is a center sectional view of the form of a transfer sheet. Sectional view during electrode layer transfer using thermal head 1 Sectional view during transfer of dielectric part using thermal head 2 Sectional view after transfer of dielectric on the same plane as the electrode layer Sectional view during dielectric layer transfer using thermal head 3 Sectional view at the time of internal electrode transfer in Example 2 Sectional view during dielectric transfer in Example 2

Explanation of symbols

1 is a dielectric ceramic layer
2 is the internal electrode layer
3 is the external electrode
4 is adhesive layer
5 is a filler layer (electrode layer)
6 is the PET layer
7 is thermal head 1
8 is a carrier film (PET layer)
9 is the internal electrode
10 is a ceramic dielectric layer (lower ineffective layer)
11 is thermal head 2
12 is the convex part of the thermal head 2
13 is a ceramic green sheet (dielectric ceramic layer)
14 is thermal head 3
15 Dielectric embedded part
16 is adhesive layer (adhesive layer)

Claims (6)

In a ceramic electronic component in which internal electrode layers and ceramic dielectric layers are alternately laminated, a ceramic green sheet uniformly held and formed on a base film such as PET and a conductive material on another base film such as PET The base film using a plurality of thermal heads capable of selectively controlling the heat generation position by pressure-bonding the internal electrode sheet formed by applying a conductive paste so that the ceramic green sheet and the internal electrode sheet face each other. A plurality of heads are moved relative to each other, and a required electrical signal corresponding to the transfer pattern is input, and the internal electrode pattern is thermally transferred from the transfer film by the heat generated by the head heat generating portion, and the dielectric portion and the dielectric. The body layer is transferred from the film using another thermal head, and the internal electrode layer is guided in the same plane. And perform a plurality of stacked bodies section are arranged consecutively, the laminated ceramic electronic component, characterized in that the formation of the external electrodes. 2. The multilayer ceramic electronic component according to claim 1, wherein at least the internal electrode layer includes a wax, a conductive metal powder, and a polymer in the heat transferable material forming the internal electrode layer and the dielectric layer. The multilayer ceramic electronic component according to claim 1, wherein the dielectric layer includes at least a wax, dielectric particles, and a polymer. In a method of manufacturing a ceramic electronic component in which internal electrode layers and ceramic dielectric layers are alternately laminated, a ceramic green sheet uniformly held and formed on a base film such as PET, and another base film such as PET Using a plurality of thermal heads that can selectively control the heat generation position and a step of pressure-bonding the internal electrode sheet formed by applying a conductive paste thereon so that the ceramic green sheet and the internal electrode sheet face each other And a step of moving a plurality of heads relative to the base film and inputting a required electrical signal corresponding to the transfer pattern to thermally transfer the internal electrode pattern from the transfer film by the heat generated by the head heat generating portion. Then, the dielectric portion and the dielectric layer are transferred from the film using another thermal head. The internal electrode layer has a step in which dielectric portions are continuously arranged in the same plane, and the steps described above are repeated to form a laminate, and an external electrode is formed. Manufacturing method of ceramic electronic components. As the polymer, polymers having different glass transition points Tg are applied, and the polymers are shifted by at least about 20 ° C. to about 50 ° C. However, the softening point is preferably lower, and the relative hardness is controlled between the internal electrode layer and the dielectric layer without depending on the adjustment of a plasticizer or the like. The internal electrode layers and the ceramic dielectric layers are alternately laminated, and the ceramic layers are disposed on the laminate so that relatively hard layers and soft layers are alternately arranged, and heating and pressurizing are performed. The multilayer ceramic electronic component using thermal transfer according to claim 4, further comprising a step of transferring a green sheet or an electrode layer onto the laminate. In the step of transferring the internal electrode layer onto the ceramic green sheet, the electrode layer may be transferred to a pre-formed ceramic green sheet, or the ceramic green sheet may be formed on the ba film and peeled off on the base film. The multilayer ceramic electronic component using thermal transfer according to claim 4 or 5, wherein the electrode layer is transferred onto the ceramic green sheet, and a method for manufacturing the same.