JP2005303029A - Method of manufacturing laminated ceramic electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise reliable performance by reducing a characteristic fault without generating a structural defect, such as a delamination, a crack, etc. of a sintered body even in the high lamination of a thin film sheet in a laminated ceramic electronic part used for various type electronic apparatuses, such as a mobile communication apparatus, a digital camera, etc. <P>SOLUTION: A first ceramic slurry to become a dielectric ceramic sheet 1 and a second ceramic slurry to become a ceramic layer 3 for absorbing a step contain a polyvinyl butyral resin as an organic binder. The second ceramic slurry is made of a polyvinyl butyral resin having a polymerization degree of 350 or less and a polyvinyl butyral resin having the polymerization degree higher than 350. The total amount of the polyvinyl butyral resins is constituted to be 5-12 wt% of a ceramic powder weight ration. Thus, the adhesive properties between the dielectric green sheets is raised by the ceramic layer 3 for absorbing the step. Further, the sheet strength of the ceramic layer for absorbing the step is assured, and the plasticity of the sheet is raised. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component used in various electronic devices.

  In recent years, electronic devices such as mobile communication devices have been reduced in size and weight, and electronic components used therefor have been required to be reduced in size and weight. For example, multilayer ceramic capacitors are required to be reduced in size, thickness and capacity, and various inventions have been made to suppress structural defects and increase reliability as the number of stacked layers increases.

  A conventional method for manufacturing a multilayer ceramic capacitor will be described below.

  As shown in FIG. 4, a conductive paste is printed on a dielectric ceramic green sheet 1 formed of a dielectric slurry to form a plurality of internal electrode layers 2, and a dielectric is formed between and at the ends of the internal electrode layers 2. The body paste is printed to form the step absorbing dielectric layer 3 having a thickness comparable to the thickness of the internal electrode layer 2. Next, the overlapping ceramic layer 4 made of the slurry is formed on the internal electrode layer 2 and the step absorbing ceramic layer 3. A predetermined number of layers are stacked so that the internal electrodes 2 of each layer have a predetermined positional relationship, and a plurality of dielectric ceramic green sheets 1 on which no internal electrodes are formed are stacked above and below the stacked body to form a ceramic raw stacked body. obtain. Next, the ceramic green laminate is pressed in the stacking direction, cut into a predetermined shape to produce individual green chips and fired, and external electrodes are formed on both end faces of the sintered body where the ends of the internal electrodes are exposed. A multilayer ceramic capacitor was obtained.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 09-106925 A

  In recent years, there has been an increasing demand for miniaturization and large capacity of multilayer ceramic capacitors, and at the same time, increasing the number of layers by reducing the thickness of dielectric layers and internal electrodes. In order to reduce the thickness of the dielectric layer, it is essential to improve the strength of the dielectric ceramic sheet. However, when the strength of the ceramic sheet is increased, there arises a problem that the adhesive strength is lowered. Therefore, in the conventional method of manufacturing a multilayer ceramic capacitor, the adhesion between the dielectric ceramic sheets is deteriorated, and structural defects such as delamination and cracks are likely to occur in the sintered body due to internal stress caused during firing. Had the problem of reducing reliability performance.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and comprises a dielectric ceramic sheet and a step-absorbing ceramic layer made of different resin compositions, and the step-absorbing ceramic layer enhances the adhesion of the ceramic sheet. As a result, even when a large number of thin-film ceramic sheets are laminated, there is no occurrence of structural defects such as delamination and cracks in the sintered body, and a method for producing a multilayer ceramic electronic component with improved reliability by reducing characteristic defects. Can be provided.

  In order to solve the above problems, the present invention has the following configuration.

  In the present invention, the first ceramic slurry to be the dielectric ceramic sheet 1 and the second ceramic slurry to be the step absorbing ceramic layer 3 contain polyvinyl butyral resin (PVB resin) as an organic binder, The rally includes a polyvinyl butyral resin having a polymerization degree of 350 or less and a polyvinyl butyral resin having a higher polymerization degree, and the total amount of the polyvinyl butyral resin is 5 to 12 wt% in terms of the weight ratio of the ceramic powder. This increases the adhesion between the dielectric green sheets, and the binder used has a low degree of polymerization, so that the organic binder can be easily degreased. Furthermore, the strength of the step-absorbing ceramic layer can be ensured, and the plasticity can be increased, and the gap between the internal electrodes can be eliminated by the pressure during lamination. As a result, even when the thin film sheet is highly laminated, there is no occurrence of structural defects such as delamination and cracks in the sintered body, and an effect of reducing characteristic defects and improving reliability performance can be obtained.

  According to the present invention, the first ceramic slurry to be a dielectric ceramic sheet and the second ceramic slurry to be a step absorbing ceramic layer contain polyvinyl butyral resin as an organic binder, and the second ceramic slurry is By comprising a polyvinyl butyral resin having a polymerization degree of 350 or less and a polyvinyl butyral resin having a higher polymerization degree than that, the total amount of the polyvinyl butyral resin is 5 to 12 wt% in terms of the ceramic powder weight ratio, The step-absorbing ceramic layer can improve the adhesion between the dielectric green sheets, and can further improve the degreasing property of the organic binder. Further, the sheet strength of the step-difference absorbing ceramic layer can be secured and the plasticity of the sheet can be increased, and the gap between the internal electrodes can be eliminated by the pressure during lamination. For this reason, there is no occurrence of structural defects such as delamination and cracks in the sintered body even when the thin film sheet is highly laminated, and the effect of reducing characteristic defects and improving reliability performance can be obtained.

  Hereinafter, the invention according to claims 1 to 4 of the present invention will be described using an embodiment.

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and an embodiment will be described taking a method for manufacturing a multilayer ceramic capacitor as an example.

  First, as shown in FIGS. 2A and 2B, a nickel paste to be the internal electrode 2 is printed on the polyester film 5 by a gravure printing method and dried to obtain the internal electrode 2 having a thickness of 2 μm or less.

  Next, as shown in FIGS. 3A and 3B, the dielectric ceramic sheet 1 and the step absorbing ceramic layer 3 are formed by the following method.

  First, in order to obtain the dielectric ceramic sheet 1, the 1st ceramic slurry which consists of the ceramic powder which has barium titanate as a main component, an organic solvent, and polyvinyl butyral resin is produced. The first ceramic slurry is formed on the polyester film 5 by a doctor blade method or the like, and a dielectric ceramic sheet 1 having a thickness of 5 μm or less is obtained through a drying process. Subsequently, a second ceramic slurry for obtaining the step absorbing ceramic layer 3 is prepared from the ceramic powder, the organic solvent, and the polyvinyl butyral resin. Using this second ceramic slurry, a step-absorbing ceramic layer 3 is formed on the dielectric ceramic sheet 1 by gravure printing so as to have a pattern shape opposite to that of the internal electrode 2 and an equivalent height. . The dielectric ceramic sheet 1 provided with the step absorbing ceramic layer 3 and the internal electrode 2 manufactured as described above are alternately laminated a plurality of times by thermal transfer so as to have a predetermined positional relationship, and step absorption is performed above and below the laminate. The dielectric ceramic sheets 1 on which the ceramic layer 3 is not formed are stacked to obtain a ceramic green laminate as shown in FIG.

  Next, the ceramic green laminate is pressed in the laminating direction, cut into a predetermined shape to produce individual green chips and fired, and external electrodes are formed on both end faces of the sintered body where the internal electrodes are exposed. To obtain a multilayer ceramic capacitor.

  In the production of the ceramic slurry, first, the first ceramic slurry to be the dielectric ceramic sheet 1 contains 9 wt% of polyvinyl butyral resin as an organic binder with respect to the weight of the ceramic powder. 30% of polyvinyl butyral resin having a polymerization degree of 350 and 70% of polyvinyl butyral resin having a polymerization degree of 1000 are contained with respect to the total amount of the resin. On the other hand, the 2nd ceramic slurry used as the level | step difference absorption ceramic layer 3 contains 7 wt% of polyvinyl butyral resin with respect to the ceramic powder weight as an organic binder. A multilayer ceramic capacitor was prepared by containing 30% of a polyvinyl butyral resin having a polymerization degree of 350 and 70% of a polyvinyl butyral resin having a polymerization degree of 800 with respect to the total amount of the resin. Sample No. 1 shown in Table 1 was obtained.

  Here, the step-absorbing ceramic layer 3 contains a low polymerization degree binder so that the adhesive strength is high, the adhesion between the dielectric ceramic sheets is increased, and the organic binder is easily degreased because of the low polymerization degree binder. Can do. Moreover, by containing a high polymerization degree binder with a low polymerization degree binder, while ensuring the intensity | strength of a ceramic layer, it has plasticity and can eliminate the clearance gap between an internal electrode with the pressure at the time of lamination | stacking. As a result, even when the thin film sheet is highly laminated, there is no occurrence of structural defects such as delamination and cracks in the sintered body, and an effect of reducing characteristic defects and improving reliability performance can be obtained.

  Similarly, the polyvinyl butyral resin in the second ceramic slurry to be the step absorbing ceramic layer 3 is contained in an amount of 7 wt% with respect to the weight of the ceramic powder, and 80% of the polyvinyl butyral resin having a polymerization degree of 350 is included with respect to the total amount of the resin. A multilayer ceramic capacitor was prepared using 20% polyvinyl butyral resin having a polymerization degree of 800, and designated as Sample No. 2 shown in (Table 1).

  Here, the step-absorbing ceramic layer 3 is further increased in adhesive strength due to an increase in the content of the low polymerization degree binder, and the adhesion between the dielectric ceramic sheets can be increased. In addition, the organic binder can be easily degreased due to the low polymerization degree binder. In addition, by containing a high degree of polymerization binder together with a low degree of polymerization binder, the strength of the ceramic layer is ensured, and high plasticity is provided. An effect is obtained that structural defects such as lamination and cracks do not occur.

  Furthermore, a multilayer ceramic capacitor was produced by setting the ratio of the ceramic powder contained in the second ceramic slurry to be the step-absorbing ceramic layer 3 to 50% or more, and designated as sample number 3 shown in (Table 1).

  Here, the density of the step-absorbing ceramic layer is increased, stress due to the density difference caused during firing is alleviated, and even when a large number of thin ceramic sheets are laminated, structural defects such as delamination and cracks in the sintered body are present. The effect that it does not occur is obtained.

  Finally, the polyvinyl butyral resin contained in the first ceramic slurry to be the dielectric ceramic green sheet 1 is 9 wt% based on the weight of the ceramic powder, of which the polyvinyl butyral resin having a polymerization degree of 1500 is 50% and the polymerization degree is 350. A monolithic ceramic capacitor was produced with 50% polyvinyl butyral resin, and designated as sample number 4 shown in Table 1.

  With this configuration, it is possible to increase the strength of the dielectric ceramic sheet, and to obtain the operational effect of increasing the reliability performance by reducing characteristic defects even when the dielectric layer is thinned.

  Although the adhesive strength of the sheet is lowered by increasing the polymerization degree of the polyvinyl butyral resin, the adhesive strength of the sheet is ensured by including a low polymerization degree binder in the step-absorbing ceramic layer 3. Generation of structural defects such as lamination and cracks can be suppressed.

  As a comparative example, the first ceramic slurry that becomes the dielectric ceramic green sheet 1 and the second ceramic slurry that becomes the step absorbing ceramic layer 3 are the same slurry based on Japanese Patent Laid-Open No. 09-10695 shown in Patent Document 1. A multilayer ceramic capacitor was produced in the same manner as in one embodiment of the present invention except that was used, and the sample number 5 shown in (Table 1) was obtained. Here, sample No. 5 was prepared using a ceramic slurry containing polyvinyl butyral resin having a polymerization degree of 800 wt% with respect to the weight of the ceramic powder.

  The characteristics and the like of the multilayer ceramic capacitors of Sample Nos. 1 to 5 (Sample No. 5 is a comparative example by a conventional method) manufactured as described above will be described below.

  Table 1 shows the results of evaluating the sintered body structural defects, the characteristic defect rate, and the reliability performance for each of the above samples. Here, the presence or absence of internal structural defects was examined by visual observation and internal observation of resin embedding for the presence or absence of delamination or cracks in the sintered body. “No (good)” when no internal structural defect occurs, and “No (impossible)” when there is an internal structural defect. The characteristic defect rate indicates the characteristic defect rate of short circuit and low withstand voltage. In addition, the reliability performance was measured by measuring the insulation resistance after applying a DC voltage twice the product rated voltage for 1000 hours in an 85 ° C. test tank. “O (good)” when there is no deterioration of insulation resistance, and “× (impossible)” when there is deterioration.

  As shown in (Table 1), the present embodiment can suppress the occurrence of internal structural defects such as delamination and cracks in the sintered body. In addition, the quality defect rate can be lowered to improve product quality and to improve reliability performance.

  As described above, according to the method for manufacturing a ceramic electronic component of the present invention, the first ceramic slurry to be the dielectric ceramic sheet 1 and the second ceramic slurry to be the step absorbing ceramic layer 3 are polyvinyl as an organic binder. The second ceramic slurry contains a polyvinyl butyral resin having a polymerization degree of 350 or less and a polyvinyl butyral resin having a higher polymerization degree, and the total amount of the polyvinyl butyral resin is 5 to 12 wt. By making the composition in%, the adhesion between the dielectric green sheets is increased, and the degreasing property of the organic binder can be enhanced because of the low polymerization degree binder. Furthermore, the sheet strength of the step-absorbing ceramic layer can be ensured and the plasticity of the sheet can be increased, and the gap between the internal electrodes can be eliminated by the pressure during lamination. As a result, even when the thin film sheet is highly laminated, there is no occurrence of structural defects such as delamination and cracks in the sintered body, and an effect of reducing characteristic defects and improving reliability performance can be obtained. Further, since the second ceramic slurry that becomes the step absorbing ceramic layer 3 is composed of a polyvinyl butyral resin having a polymerization degree of 350 or less and a polyvinyl butyral resin having a higher polymerization degree, the second ceramic slurry becomes the dielectric ceramic sheet 1. The amount of the organic binder can be reduced as compared with the ceramic slurry of 1, the degreasing property of the organic binder can be increased, and the adhesion between the green chips can be reduced. In this embodiment, the total amount of the polyvinyl butyral resin is 5 to 12 wt% in terms of the weight ratio of the ceramic powder. However, if it is less than 5 wt%, sufficient sheet adhesiveness cannot be obtained, whereas if it exceeds 12 wt% Increases the adhesion (attachment) between green chips, resulting in decreased productivity.

  Moreover, the polyvinyl butyral resin having a polymerization degree of 350 or less contained in the second ceramic slurry is configured to be 70% or more of the total resin amount, thereby ensuring the sheet strength of the step absorbing ceramic layer 3 and the sheet. The plasticity is improved, and there is an effect that the structural pressure such as delamination and cracks of the sintered body is not generated by eliminating the gap between the internal electrodes due to the pressure at the time of lamination.

  Further, by configuring the ratio of the ceramic powder contained in the second ceramic slurry to be 50% or more, the sheet density of the step absorbing ceramic layer is increased, and the stress due to the difference in sheet density caused during firing is reduced, The effect of preventing structural defects such as delamination and cracks in the sintered body can be obtained even when the thin film sheet is highly laminated.

  Further, in the present embodiment, the resin composition of the first ceramic slurry is composed of two types of polyvinyl butyral resin having a polymerization degree of 1500 or more and polyvinyl butyral resin having a polymerization degree of 350 or less, and the polyvinyl butyral resin having a polymerization degree of 1500 or more is By configuring it to be 50% or more of the total resin amount, the strength of the dielectric green sheet can be increased. Furthermore, since the ratio of the low polymerization degree binder is high, the degreasing property of the organic binder can be improved. As a result, even when the dielectric layer is thinned, the effect of reducing the characteristic defect and improving the reliability performance can be obtained.

  In this embodiment, the step-absorbing ceramic layer is formed on the dielectric ceramic sheet. However, the dielectric ceramic sheet, the step-absorbing ceramic layer, and the internal electrodes are individually produced on a support such as a polyester film. Each of them may be sequentially laminated by a method such as transfer.

  Alternatively, an internal electrode may be formed on a dielectric ceramic sheet, and a step-absorbing ceramic layer may be formed on another support such as a polyester film, and laminated by a method such as transfer.

  Further, the same effect can be obtained by forming and laminating the internal electrode and the step absorbing ceramic layer 3 on the dielectric ceramic sheet.

  In the present embodiment, the internal electrode 2 and the step absorbing ceramic layer 3 are formed by the gravure printing method, but the same effect can be obtained even if they are formed by the screen printing method. Further, the step absorbing ceramic layer 3 is formed in a pattern shape opposite to that of the internal electrode 2, but the same effect can be obtained if it is formed in a stripe shape in a region in the width direction where the internal electrode 2 is not formed. It is done.

  The dielectric ceramic sheet 1 and the step-absorbing ceramic layer 3 can achieve the same effect even in polyacetals other than polyvinyl butyral resin.

  The manufacturing method of the multilayer ceramic electronic component of the present invention is not limited to multilayer ceramic capacitors used in various electronic devices such as mobile communication devices and digital cameras, but also various multilayer ceramic electronic components such as multilayer ceramic thermistors and multilayer ceramic varistors. Useful as a method.

Sectional drawing which shows the state which formed the dielectric material ceramic sheet, the internal electrode, and the ceramic layer for level | step difference absorption in one embodiment of this invention (A), (b) The perspective view which shows the state which formed the internal electrode on the film, and sectional drawing (A), (b) The perspective view which shows the state which formed the dielectric ceramic sheet and the ceramic layer for level | step difference absorption on the film, and sectional drawing Sectional drawing which shows the structure of a raw laminated body in the manufacturing method of the conventional multilayer ceramic electronic component

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric ceramic sheet 2 Internal electrode 3 Ceramic layer for level | step difference absorption 4 Ceramic layer for stacking 5 Polyester film

Claims (4)

A first step of forming a ceramic sheet by forming a first ceramic slurry; a second step of forming a plurality of electrode portions in a pattern on the ceramic sheet; and forming an electrode portion on the ceramic sheet A third step of forming a step-absorbing ceramic layer made of the second ceramic slurry in an unfinished region, and a fourth step of stacking a plurality of ceramic sheets obtained in the third step to produce a ceramic green laminate And a fifth step of pressing the ceramic raw laminate in the stacking direction and cutting it into a predetermined shape, followed by firing, and a sixth step of forming external electrodes on both end faces of the sintered body, The first and second ceramic slurries contain polyvinyl butyral resin as an organic binder, and the second ceramic slurry is a polyvinyl chloride having a polymerization degree of 350 or less. Multilayer ceramic containing a butyral resin and two types of polyvinyl butyral resins having a higher degree of polymerization, and the total amount of polyvinyl butyral resin in the second ceramic slurry is 5 to 12 wt% by weight with respect to the ceramic powder Manufacturing method of electronic components. As the second ceramic slurry, a polyvinyl butyral resin having a polymerization degree of 350 or less contained in the second ceramic slurry is one that is 70 wt% or more of the total resin amount contained in the second ceramic slurry. Item 2. A method for producing a multilayer ceramic electronic component according to Item 1. The method for producing a multilayer ceramic electronic component according to claim 1, wherein the second ceramic slurry includes a ceramic powder, an organic solvent, and an organic binder, and the weight ratio of the ceramic powder to the entire ceramic slurry is 50 wt% or more. . The first ceramic slurry includes two types of butyral resins: a polyvinyl butyral resin having a polymerization degree of 1500 or more and a polyvinyl butyral resin having a polymerization degree of 350 or less. The polyvinyl butyral resin having a polymerization degree of 1500 or more is contained in the first ceramic slurry The method for producing a multilayer ceramic electronic component according to claim 1, wherein a material having a total resin amount of 50 wt% or more is used.

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