JP2006128282A - Multilayer electronic component and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a highly reliable multilayer electronic component and a method for manufacturing the same by suppressing insulation failure and reliability failure due to deformation of a conductor layer inside an electronic component body.
A conductive layer 7 in the effective portion 9 is bent, the effective portion 9 is divided into two portions with the same thickness in the stacking direction, the upper layer side is the upper effective portion 9a, and one lower layer side is the lower portion The effective portion 9b, and of the conductor layer 7, the surface of the effective layer conductor layer 7b of the conductor layer 7 in the upper effective portion 9a is used as a reference plane 7c, and a part of the conductor layer 7 is the reference plane. The amount of deformation at the position farthest in the stacking direction from 7c is tr1, and the amount of deformation tr2 when the conductor layer 7 in the lower effective portion 9b is at the position farthest from the reference plane 7c in the stacking direction. The relationship of tr1 / tr2 = 0.8 to 1.2 is satisfied.
[Selection] Figure 1

Description

  The present invention relates to a multilayer electronic component and a method for manufacturing the same, and more particularly to a multilayer electronic component including an electronic component body in which a large number of thin ceramic layers and conductor layers are stacked and a method for manufacturing the same.

  For example, a multilayer ceramic capacitor, which is a typical example of a multilayer electronic component, includes an effective portion in which a ceramic layer as a dielectric and a conductor layer such as nickel are alternately disposed, and a ceramic layer as a cover layer on both upper and lower sides thereof. And an external electrode electrically connected to the conductor layer in the effective portion. In recent years, with the further miniaturization and higher functionality of electronic components, multilayer ceramic capacitors have been promoted to be smaller and have higher capacities, and the thickness (distance between internal electrodes) of the ceramic layer that is a dielectric constituting the multilayer ceramic capacitor is 10 μm or less. The number of laminated ceramic layers and conductor layers is 100 or more.

  Such a multilayer ceramic capacitor is manufactured by laminating a plurality of ceramic green sheets having a conductor pattern and pressurizing and heating them. However, since the ceramic green sheets are extremely thin in recent years, In the conductor layer formed on the conductor layer, a step due to its thickness cannot be ignored. In particular, structural defects such as delamination and pores are generated at the interface between the outer cover layer and the effective layer of the multilayer ceramic capacitor.

As a measure for solving such a problem, as shown in FIG. 4, a dummy conductor layer 101 or a ceramic layer 101 for eliminating a step is formed on the opposite side of the inner conductor layer connected to the external electrode 100. (For example, Patent Document 1), as disclosed in Patent Document 2 below, a ceramic green sheet for forming an effective portion of the plasticizer or solvent content of the cover sheet used for the cover layer The structural defect generated at the interface between the cover layer and the effective portion is further suppressed by flowing a part of the cover sheet into the step.
JP 2000-311831 A JP-A-9-129487

  However, the dummy conductor layer or the ceramic layer for eliminating the step as described above is formed in the vicinity of the conductor layer in the electronic component main body, or the cover sheet is plasticized by a plasticizer or a solvent, and the inner step portion Even after flowing into the lower layer side, the green sheet on the lower layer side, the laminate on which the green sheet and the conductor pattern are superimposed, and the cover sheet on the upper layer side are temporarily laminated. In the case of a multilayer electronic component formed by a manufacturing method in which lamination is performed by applying high temperature and high pressure, the conductor layer inside the electronic component body is still caused by the manufacturing process such as deformation of the cover sheet by the pressure heating. There was a problem that large deformation occurred and insulation failure and reliability failure were likely to occur.

  Accordingly, it is an object of the present invention to provide a highly reliable multilayer electronic component and a method for manufacturing the same, by suppressing insulation failure and reliability failure due to deformation of a conductor layer inside the electronic component body.

  A multilayer electronic component according to the present invention includes: (1) an electronic component body including an effective portion formed by alternately laminating ceramic layers and conductor layers, and cover layers provided on upper and lower outer layers of the effective portion. In the multilayer electronic component, wherein the conductor layer includes a lead portion conductor layer led out to at least one end surface of the effective portion and an effective portion conductor layer for realizing capacitance, in the effective portion The conductor layer is in a bent state, the effective portion is divided into two with equal thickness in the stacking direction, the upper layer side is the upper effective portion, one lower layer side is the lower effective portion, and the upper portion of the conductor layer The effective portion of the conductor layer in the effective portion is defined as a reference plane, the deformation amount when a part of the conductor layer is farthest from the reference plane in the stacking direction is tr1, and the lower effective portion The conductor layer in the section When the deformation amount tr2 when farthest to the stacking direction from the reference surface, and satisfies the relation of tr1 / tr2 = 0.8 to 1.2.

  In the multilayer electronic component, (2) a dummy conductor layer is formed on the same ceramic layer surface as the conductor layer, and the dummy conductor layer is only a distance G away from the effective portion conductor layer on the side opposite to the lead portion conductor layer. (3) the conductor layer and the dummy conductor layer are substantially the same thickness; (4) the distance G is 100 times or less the conductor layer thickness; It is preferable that the number is 100 or more, (6) the thickness of the ceramic layer is 2 μm or less, and (7) the thickness of the conductor layer and the dummy conductor layer is 1 μm or less.

  And the manufacturing method of the multilayer electronic component of the present invention is (8) an electronic component main body formed by laminating a cover sheet on the upper and lower surfaces of an effective laminate in which a plurality of ceramic green sheets and conductor patterns are alternately laminated. In the method for producing a multilayer electronic component for firing the laminate, the degree of polymerization of the binder contained in the upper surface side cover sheet is higher than the degree of polymerization of the binder contained in the lower surface side cover sheet.

  According to the present invention, after temporarily laminating the cover sheet on the lower surface side, the effective laminate on which the green sheet and the conductor pattern are superimposed, and the cover sheet on the upper surface side in order, the pressure and heating conditions of the temporary laminate Even in a multilayer electronic component formed by a manufacturing method in which a higher temperature and a higher pressure are applied, the degree of polymerization of the binder contained in the cover sheet on the upper surface side is first exposed to a heated and pressurized state several times. By using a material having a higher degree of polymerization than the binder contained in the lower surface cover sheet, it is possible to suppress deformation of the conductor layer on the upper surface side in the electronic component main body laminate, even after pressurization and heating. Insulation failure and reliability failure due to deformation of the conductor layer inside the electronic component body later can be suppressed, whereby a highly reliable multilayer electronic component can be obtained.

(Construction)
A multilayer ceramic capacitor, which is a representative example of the multilayer electronic component of the present invention, will be described in detail. FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to the present invention. In the multilayer ceramic capacitor of the present invention, external electrodes 3 are formed on the opposing end surfaces of the electronic component body 1. The electronic component body 1 includes an effective portion 9 formed by alternately laminating ceramic layers 5 and conductor layers 7, and cover layers 11 provided on upper and lower outer layers of the effective portion 9. The conductor layer 7 includes, in the effective portion 9, an extraction portion conductor layer 7 a led to one end surface of the electronic component main body 1 and an effective portion conductor layer 7 b for realizing capacitance.

  FIG. 2 is a schematic cross-sectional view of a multilayer ceramic capacitor having a dummy conductor layer according to the present invention. This multilayer ceramic capacitor is formed on the same ceramic layer surface as the conductor layer 7 by a distance G to the effective conductor layer 7b opposite to the lead conductor layer 7a led out to the end face 2 of the electronic component body 1 of the conductor layer 7. A dummy conductor layer 15 that does not contribute to the formation of a capacitor formed apart from each other is formed.

  In the multilayer electronic component according to the present invention, the effective portion 9 is divided into two parts with the same thickness in the stacking direction, the upper layer side being the upper effective portion 9a, and one lower layer side being the lower effective portion 9b, When the conductor layer 7 is bent in the effective portion 9, the position of the conductor layer 7 farthest from the reference surface 7c in the stacking direction is set as the maximum deformation amount tr1, When the conductor layer 7 in the component body 1b is in a bent state and the position farthest from the reference surface 7c of the conductor layer 7 in the stacking direction is the maximum deformation amount tr2, tr1 / tr2 = It is important to satisfy the relationship of 0.8 to 1.2.

  In particular, tr1 / tr2 = 0.9 to 1.1 is preferable in that the thickness variation of the ceramic layer 5 constituting the electronic component body 1 is reduced to reduce the capacitance variation.

  On the other hand, when tr1 / tr2 is smaller than 0.8 or larger than 1.2, the thickness variation of the ceramic layer 5 due to the deformation of the conductor layer 7 increases, and the variation in insulation and capacitance increases.

In the present invention, the state in which the conductor layer 7 is bent includes the bending of the end of the conductor layer 7 and the curved deformation of the conductor layer 7 sandwiching the distance G formed between the conductor layer 7 and the dummy conductor layer 15. . In addition to this, not only bending but also deformation with an angle is included. Or between the dummy conductor layer 15 formed in the plane of the conductor layer 7 sandwiching the effective portion conductor layer 7b,
In the multilayer electronic component according to the present invention, it is preferable that (3) the thicknesses t and td of the conductor layer 7 and the dummy conductor layer 15 are substantially the same. The thicknesses t and td of the conductor layer 7 and the dummy conductor layer 15 are preferably 2 μm or less, and the substantially same thickness means that the difference in the thickness of the conductor is within 10%.

  (4) The distance G between the conductor layer 7 and the dummy conductor layer 15 (the distance between the effective portion conductor layer 7b and the dummy conductor layer 15) is the conductor layer 7 positioned above and below the distance G in the stacking direction. The thickness of the conductor layer is preferably 100 times or less from the standpoint of reducing the deformation and improving the insulation and suppressing defects such as delamination.

  Further, according to the present invention, (6) the thickness of the ceramic layer is 2 μm or less, (7) the thickness of the conductor layer and the dummy conductor layer is 1 μm or less, and (5) a thin layer having 100 or more layers. It is suitable for highly laminated multilayer electronic components.

(Manufacturing method)
FIG. 3 is a schematic view for manufacturing the multilayer electronic component of the present invention. When producing the multilayer ceramic capacitor according to the present invention, in the step (a), first, a ceramic powder mainly composed of barium titanate, a binder, a solvent for dissolving the binder, a plasticizer and a dispersant. A ceramic slurry is prepared by mixing with an additive such as, and the ceramic green sheet 23 is formed using a sheet forming method such as a die coater method or a doctor blade method.

  Next, in the step (b), a pattern group in which a plurality of conductor patterns 25 are arranged in a staggered pattern on one main surface of the obtained ceramic green sheet 23 is formed. In this pattern group, for example, the rectangular conductor pattern 25 is formed by shifting a half pattern in the longitudinal direction. Further, a step eliminating ceramic pattern 29 may be formed on the outer periphery of the conductor pattern 25 as in step (c).

  Next, in the step (d), a plurality of ceramic green sheets on which a pattern group is not formed are placed on a support serving as a heating medium for temporary lamination. This becomes the lower cover sheet 23b. Next, a desired number of ceramic green sheets having pattern groups are stacked on the upper surface of the lower cover sheet 23b to form a laminate in which the ceramic green sheets 23 and the conductor patterns 25 are stacked. In this case, the upper and lower conductor patterns are stacked in a state of being shifted by a half pattern.

  Next, the upper layer side cover sheet 23a is overlaid on the upper surface of the layered body so as to have substantially the same thickness as the lower layer side cover sheet 23b, thereby forming a temporary layered body 31.

  In the present invention, the degree of polymerization of the binder contained in the upper layer side cover sheet 23a is higher than the degree of polymerization of the binder contained in the lower layer side cover sheet 23b. is there. That is, the ceramic green sheet 23 used here changes the degree of polymerization of the binder as a method for controlling its heat resistance and volatility such as solvent and plasticizer. When a binder having the same degree of polymerization is used for the lower cover sheet 23b and the upper cover sheet 23a, for example, when pressure is applied at a high temperature during lamination, the time of exposure to the heating state is short. The cover sheet 23a on the upper layer side is likely to be deformed. On the other hand, when pressurization is performed at a low temperature, the adhesion of the cover sheet 23b on the lower layer part side that is exposed to a heated state decreases for a long time. Defects such as lamination are likely to occur.

  The composition of the binder contained in the lower cover sheet 23b is such that the weight ratio of the first binder having a low polymerization degree and the second binder having a high polymerization degree is first binder: second binder = 80: 20-60: 40 is desirable.

  On the other hand, the composition of the binder contained in the upper cover sheet 23a is such that the weight ratio of the first binder having a low degree of polymerization and the second binder having a high degree of polymerization is the first binder: second binder = 40: 60-60: 40 is preferable.

  It should be noted that the binder contained in the ceramic green sheet that forms the conductor pattern and has a laminated structure is such that the weight ratio of the first binder having a low polymerization degree and the second binder having a high polymerization degree is the first binder: second. The binder may be 80:20 to 60:40. In addition, as for the polymer polymerization degree of a binder, it is desirable that the 1st binder polymerization degree is 100-300 and the 2nd binder polymerization degree is 1000-2000. In the present invention, the pressure when forming the temporary laminate is 1 to 10 Pa, the temperature is 50 to 100 ° C., and the pressure when forming the electronic component body laminate by pressurizing and heating the temporary laminate again is 5 to 100 Pa. The temperature is preferably 70 to 130 ° C.

  Next, in steps (e) and (f), this temporary laminate 31 is heated under pressure and pressure higher than the pressure and temperature at which the temporary laminate 31 is formed to produce a ceramic green sheet. 23 and the conductor pattern 25 are alternately laminated, and the electronic component main body laminate 35 is formed, and the cutting line h is cut into a predetermined shape.

  In the above manufacturing method, the method of laminating a sheet in which a conductor pattern is formed in advance on one main surface of the ceramic green sheet has been described in detail, but as another method, a conductor pattern is formed on the upper surface of the lower layer side ceramic green sheet, Next, the laminate of the present invention can also be formed by repeating the process of superimposing another ceramic green sheet on the upper surface of the ceramic green sheet on which the conductor pattern is formed.

  Here, the thickness of the ceramic green sheet is preferably 3 μm or less, and the thickness of the conductor pattern is preferably 2 μm or less. As the conductor pattern, a metal film such as a plating film can be suitably used in addition to a conductor paste containing metal powder.

The metal component is preferably a base metal such as nickel or copper from the viewpoint of reducing the electrode cost of the multilayer ceramic capacitor.

  When the multilayer ceramic capacitor having the dummy conductor layer shown in FIG. 2 is manufactured, the method of manufacturing the multilayer ceramic capacitor of FIG. 1 can be used as it is except that the shape of the conductor pattern is different.

Next, examples of the present invention are shown below. First, a ceramic green sheet serving as an effective portion was produced. As the ceramic powder used for the ceramic slurry of this sheet, BaTiO ₃ powder having an average particle size of 0.3 μm was used, and 0.6 μm glass (SiO ₂ ) powder having an average particle size of 0.6 μm was used as a sintering aid. BaTiO _{3 is} added to a binder solution in which polyvinyl butyral and a plasticizer are dissolved in a mixed solvent in which toluene and ethanol are mixed at a weight ratio of 1: 1 as a solvent for the ceramic slurry for the effective layer and the cover layer according to the present invention. The ceramic slurry was prepared by adjusting the powder and glass powder at a predetermined mixing ratio and dispersing them with a ball mill. The thickness of the sheet was 3 μm, 6 μm, and 8 μm. The cover sheet was made with a thickness of 10 μm.

  The composition of the polyvinyl butyral binder contained in the ceramic green sheet for the effective layer is such that the weight ratio of the first binder having a low polymerization degree to the second binder having a high polymerization degree is the first binder: second binder = 50. : 50. As the ceramic cover for the outer cover sheet, the above polyvinyl butyral is used as a binder, and the weight ratio of the first binder to the second binder is adjusted as shown in Table 1 for this polyvinyl butyral. A ceramic slurry was produced by the production method. As the degree of polymerization of the binder contained in the ceramic slurry, a binder having a distribution with a first binder polymerization degree of 100 to 300 and a second binder polymerization degree of 1000 to 2000 was used.

  Next, a conductive paste containing Ni is applied to a ceramic green sheet that is an effective part of each thickness to form a conductive pattern having a pattern that becomes a dummy conductive layer, and a gap of 20 μm is formed on the outer periphery of the internal electrode pattern to eliminate a step. A ceramic paste was printed. Next, 10 green sheets on which a pattern group was not formed were placed on a support serving as a heating medium for temporary lamination to obtain a lower layer side ceramic green sheet.

  Next, a desired number of ceramic green sheets on which pattern groups were formed were stacked on the upper surface of the lower ceramic green sheet to form a laminate in which the ceramic green sheets and conductor patterns were superimposed. The number of layers was 200. In this case, the upper and lower conductor patterns were stacked in a state of being shifted by a half pattern.

  Next, an upper layer side ceramic green sheet was stacked on the upper surface of the laminate so as to have substantially the same thickness as the lower layer side ceramic green sheet to form a temporary laminate.

  Next, this temporary laminate is heated under pressure and pressure higher than the temperature and temperature at which the temporary laminate is formed, and the ceramic green sheets and the conductor patterns are alternately laminated. A component body laminate was formed.

Next, this electronic component body laminate was cut to produce a capacitor body molded body, and after degreasing treatment, firing was performed in a reducing atmosphere. Firing is performed at a maximum temperature of 1280 ° C. for 2 hours in a reducing atmosphere (PO ₂ = 10 ⁻⁷ Pa), and then reoxidized at 1000 ° C. in a weakly oxidizing atmosphere (PO ₂ = 10 ⁻³ Pa). Finally, a copper paste was applied to the exposed end of the obtained capacitor body, and baked in a reducing atmosphere (PO ₂ = 10 ⁻² Pa) at 800 ° C. for 1 hour. Table 1 shows the combination of the effective portion and the cover layer, the model of the produced laminate, the height dimension (mm), and the number of laminations.

  The deformation of the conductor in the capacitor body was determined based on the level surface from a cross-sectional observation electron micrograph. At this time, the capacitor body was divided into two parts with a uniform thickness in the stacking direction.

Further, as an evaluation of the structural defect, an occurrence rate of delamination generated in 100 multilayer ceramic capacitors was obtained. In addition, in order to accelerate and evaluate the incidence of structural defects,
An accelerated test was conducted. For insulation, the breakdown voltage was determined. The dielectric breakdown voltage was examined by increasing the voltage until breakdown. The dielectric breakdown voltages of the samples of the present invention were all 200 V or more when the dielectric layer thickness was 3 μm.

On the other hand, as a comparative example, the same multilayer ceramic green sheet was prepared using ceramic green sheets having the same weight ratio of the first binder and the second binder in the binder of the outer cover sheet and the effective portion sheet, and the same Was evaluated. The results are shown in Table 1 together with the results of the present invention. The dielectric breakdown voltage of the samples other than the present invention was 70 V or less at the dielectric layer thickness of 3 μm.

  As is clear from the results in Table 1, when the deformation ratio of the conductor layer, which is a sample of the present invention, is 0.8 to 1.2, peeling occurs due to the firing shrinkage difference between the upper and lower outer cover layers or between the effective layers. It can be seen that cracking or delamination is suppressed.

  For comparison, multilayer ceramic capacitors made with the same porcelain composition of the outer cover sheet and the dielectric effective layer generate 50% of cracks or delamination at the interface between the outer cover layer and the dielectric effective layer of all multilayer ceramic capacitors. I was letting.

  Further, although the present invention has a dummy electrode for eliminating the step or a dielectric layer for eliminating the step, depending on the combination of the thickness of the dielectric ceramic layer and the number of stacked layers, the dummy electrode for eliminating the step or the dielectric for eliminating the step is provided. Obviously, even in the absence of a body layer (FIG. 1), the effect is maintained and is within the scope of the invention.

It is a schematic sectional drawing of the multilayer electronic component which does not have the dummy conductor layer of this invention. It is a schematic sectional drawing of the multilayer electronic component which has a dummy conductor layer of this invention. It is a schematic diagram for manufacturing the multilayer electronic component of the present invention. It is a schematic sectional drawing of the conventional multilayer electronic component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic component body 3 Ceramic body 5 Ceramic layer 7 Conductor layer 7a Lead part conductor layer 7b Effective part conductor layer 9 Effective part 9a Upper effective part 9b Lower effective part 11 Cover layer 13 End part 15 Dummy conductor layer G Conductor layer and dummy conductor Distance to layer

Claims (8)

The electronic component main body includes an effective portion formed by alternately laminating ceramic layers and conductor layers, and cover layers provided on upper and lower outer layers of the effective portion, and the conductor layer includes the effective portion. In a laminated electronic component comprising at least a lead portion conductor layer led to one end face and an effective portion conductor layer for realizing capacitance, the conductor layer in the effective portion is bent, and the effective portion The effective layer conductor layer of the conductor layer in the upper effective portion of the conductor layer, and the upper layer side as the upper effective portion and the lower layer side as the lower effective portion. And the amount of deformation when a part of the conductor layer is farthest from the reference plane in the stacking direction is tr1, and the conductor layer in the lower effective portion is stacked from the reference plane in the stacking direction. Most distant And the amount of deformation when in position when the tr2, the multilayer electronic component which satisfies the relationship of tr1 / tr2 = 0.8~1.2. The dummy conductor layer is formed on the same ceramic layer surface as the conductor layer, and the dummy conductor layer is formed by being separated from the effective portion conductor layer on the side opposite to the lead portion conductor layer by a distance G. The laminated electronic component described. The multilayer electronic component according to claim 1, wherein the conductor layer and the dummy conductor layer have substantially the same thickness. The multilayer electronic component according to any one of claims 1 to 3, wherein the distance G is 100 times or less the conductor layer thickness. The multilayer electronic component according to claim 1, wherein the number of layers is 100 or more. The multilayer electronic component according to claim 1, wherein the thickness of the ceramic layer is 2 μm or less. The multilayer electronic component according to claim 1, wherein the conductor layer and the dummy conductor layer have a thickness of 1 μm or less. In the manufacturing method of a multilayer electronic component in which an electronic component main body laminate formed by laminating a cover sheet is fired on the upper and lower surfaces of an effective laminate in which a plurality of ceramic green sheets and conductor patterns are alternately laminated, the upper surface side A method for producing a multilayer electronic component, wherein the degree of polymerization of the binder contained in the cover sheet is higher than the degree of polymerization of the binder contained in the lower cover sheet.

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