JP2011018848A - Method of manufacturing electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electronic component that can enhance polishing efficiency of a green chip containing a plasticizer, suppress defects (chipping etc.) of the electronic component, and suppress deterioration in electric characteristics such as a withstand voltage fraction defective.SOLUTION: The method of manufacturing the electronic component includes a process of preparing the unbaked green chip containing the plasticizer, and a process of polishing the green chip, wherein the glass transition temperature Tg of the green chip right before the polishing process is ≤40°C, and the temperature Tc of the green chip in the polishing process is lower than the glass transition temperature Tg by 25°C or more.

Description

  The present invention relates to a method for manufacturing an electronic component, and more particularly to a method for manufacturing an electronic component that can increase the polishing efficiency of a green chip containing a plasticizer and is excellent in electrical characteristics.

  Examples of electronic components mounted on electronic devices include multilayer ceramic electronic components such as capacitors, bandpass filters, inductors, multilayer three-terminal filters, piezoelectric elements, PTC thermistors, NTC thermistors, or varistors. ing. For the capacitor element body constituting these multilayer ceramic electronic components, for example, a rectangular parallelepiped green chip composed of a green sheet and a predetermined pattern of internal electrode pattern layers is prepared, and corners and ridges are polished simultaneously. Manufactured by firing.

  Further, the green sheet or the internal electrode pattern layer is often used containing a plasticizer such as phthalate ester, adipic acid, phosphate ester or glycol. By including a plasticizer, the green sheet and the internal electrode pattern layer can have good elongation and flexibility, and the laminating property can be improved.

  As a handling of the green chip containing such a plasticizer, Patent Document 1 describes that in order to reduce the shrinkage rate of the ceramic body before and after firing, the green ceramic body containing the plasticizer is solidified before polishing. Incorporates a drying process.

  However, conventionally, in the polishing process of a green chip containing a plasticizer, it has not been a problem that the polishing efficiency is lowered due to the flexibility of the green chip due to the presence of the plasticizer. In addition, since the plasticizer component is removed by solidification drying, voids are formed at the locations where the plasticizer has been removed, and it is easy to absorb moisture in the subsequent process, which may cause structural defects. In addition, there has been little research on the relationship between the solidification drying process and the polishing process and the electrical characteristics of electronic components.

JP 2005-79484 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a method of manufacturing an electronic component that can increase the polishing efficiency of a green chip containing a plasticizer and is excellent in electrical characteristics.

  As a result of intensive studies on polishing of a green chip containing a plasticizer, the present inventors have found the following problems and completed the present invention. That is, it has been found that when the green chip contains a plasticizer, the green chip becomes flexible and the polishing efficiency decreases.

  Further, such a decrease in polishing efficiency leads to defects (chips, chipping, etc.) of electronic components. Further, the present inventors have found that a withstand voltage failure may occur depending on conditions of the polishing process or conditions such as solidification drying performed before the polishing process.

Therefore, in order to solve the above problems, a method of manufacturing an electronic component according to the present invention is as follows.
Preparing an unfired green chip containing a plasticizer;
Polishing the green chip;
Have
The glass transition temperature Tg of the green chip immediately before the polishing step is 40 ° C. or less,
The temperature Tc of the green chip in the polishing process is 25 ° C. or more lower than the glass transition temperature Tg.

  Preferably, the green chip is polished by dry barrel polishing.

  Preferably, the temperature Tc of the green chip in the polishing process is 30 ° C. or more lower than the glass transition temperature Tg.

  Preferably, the temperature Tc of the green chip in the polishing process is 10 ° C. or less.

  Preferably, the method further includes a step of firing the green chip after the polishing step.

Preferably, the plasticizer is at least one selected from DOP (dioctyl phthalate), DBP (dibutyl phthalate), and BBP (butyl benzyl phthalate).
Preferably, barrel polishing is performed in a state where the green chip has a plasticizer immediately after preparing the green chip (immediately after the cutting process) without performing the solidification drying process. Here, not performing the solidification drying process means that the plasticizer is not actively heated under the condition of removing the plasticizer (about 180 ° C.). Not done. In addition to being able to omit the solidification drying step that has been required for green chips containing a plasticizer in the past, barrel polishing is performed with the plasticizer contained, so that the strength of the chip can be secured. In addition, it is possible to simplify the process and prevent the element body from absorbing moisture after the next process and causing structural defects.

  According to the present invention, it is possible to increase the polishing efficiency of a green chip containing a plasticizer, to suppress defects (chips, chipping, etc.) of electronic components and to deteriorate electrical characteristics such as a withstand voltage failure rate. The manufacturing method of the electronic component which can be suppressed can be provided.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2A is a process schematic diagram showing a manufacturing process of the multilayer ceramic capacitor shown in FIG. FIG. 2b is a process schematic diagram showing a continuation process of FIG. 2a. FIG. 2c is a process schematic diagram showing a continuation process of FIG. 2b. FIG. 3A is a perspective view of a green chip before a barrel polishing step used for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention, and FIG. 3B is a barrel polishing step shown in FIG. It is the schematic sectional drawing which cut | disconnected the previous green chip along the IIIB-IIIB line. 4A is a perspective view of a green chip after a barrel polishing process used for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention, and FIG. 4B is a barrel polishing process shown in FIG. 4A. It is the schematic sectional drawing which cut | disconnected the subsequent green chip along the IVB-IVB line. FIG. 5 is an enlarged cross-sectional view in which the corner portion V of the green chip after the barrel polishing step shown in FIG. FIG. 6 shows the relationship of the withstand voltage failure rate with respect to Tg in the embodiment of the present invention. FIG. 7 shows the relationship between the chip defect rate and the corner R value with respect to Tg-Tc in the example of the present invention.

  The electronic component manufactured by the manufacturing method according to an embodiment of the present invention is not particularly limited, and examples thereof include surface mount components such as multilayer inductors, multilayer varistors, and resistors. In this embodiment, a multilayer ceramic capacitor is illustrated.

Overall Configuration of Multilayer Ceramic Capacitor As shown in FIG. 1, a multilayer ceramic capacitor 2 according to an embodiment of the present invention includes a capacitor element body 4 having a configuration in which dielectric layers 10 and internal electrode layers 12 are alternately stacked. Have. A pair of external electrodes 6 and 8 are formed on both side ends of the capacitor element body 4 so as to be electrically connected to the internal electrode layers 12 arranged alternately in the capacitor element body 4.

  The internal electrode layers 12 are laminated so that the side end faces are alternately exposed on the surfaces of the opposite end portions of the capacitor element body 4. The pair of external electrodes 6 and 8 are formed at both ends of the capacitor element body 4 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 12 to constitute a capacitor circuit.

  The capacitor element body is manufactured, for example, by polishing and simultaneously firing a green chip composed of a green sheet and a predetermined pattern of internal electrode pattern layers.

Plasticizer The green chip in the present embodiment includes a plasticizer. Specifically, a plasticizer is contained in the green sheet and the internal electrode pattern layer constituting the green chip. By including a plasticizer, the green sheet and the internal electrode pattern layer can have good elongation and flexibility, and the laminating property can be improved.

  However, as described above, when the green chip is polished, the temperature of the green chip rises due to friction. Therefore, the green chip containing the plasticizer tends to have higher flexibility and lower polishing efficiency. is there.

  In the present embodiment, in view of such a situation, the polishing efficiency is improved by controlling the green chip immediately before polishing to a predetermined glass transition temperature Tg and a temperature Tc of the green chip in the polishing step to a predetermined range. Features. Specifically, the glass transition temperature Tg of the green chip immediately before polishing is 40 ° C. or lower, preferably 30 to 35 ° C. or lower. Further, the temperature Tc of the green chip in the polishing process is 25 ° C. or more, preferably 30 ° C. or more lower than Tg. Furthermore, preferably, the temperature Tc of the green chip in the polishing step is 10 ° C. or lower, more preferably −40 to 10 ° C.

  In addition, the glass transition temperature Tg of the green chip can be controlled by adjusting the amount of the plasticizer contained in the dielectric ceramic green sheet among the plasticizers contained in the green chip. Tg tends to decrease as the amount of plasticizer contained in the ceramic green sheet is increased.

  In addition, the glass transition temperature Tg can also be controlled by the type and content of the organic vehicle and the plasticizer contained in the green sheet or the internal electrode pattern layer.

  Examples of the plasticizer used in this embodiment include phthalate esters such as dioctyl phthalate and dibutyl phthalate, adipate esters such as phthalate adipate (DOA), phosphate esters such as tricresyl phosphate, and butylphthalylbutyl. Glycols such as glycolate are exemplified, but dioctyl phthalate is preferred.

  The boiling point of the plasticizer is preferably 100 ° C. or higher (760 mmHg).

Dielectric layer 10 of the green sheet Figure 1 is obtained by firing the green sheet 10a shown in Figure 2a, the green sheet is obtained by molding a dielectric layer paste.

  First, a dielectric layer paste is prepared. The dielectric layer paste is generally composed of an organic solvent-based paste obtained by kneading ceramic powder (dielectric material) and an organic vehicle, or an aqueous paste. In the present embodiment, these pastes are preferably organic solvent-based pastes.

  The raw material of the ceramic powder contained in the dielectric layer paste in the present embodiment is not particularly limited, but is appropriately selected from various compounds that become composite oxides and oxides, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like. They can be selected and mixed for use.

  An organic vehicle is obtained by dissolving a binder resin in an organic solvent. The organic binder used in the organic vehicle in the present embodiment is not particularly limited, but acrylic resin, ethyl cellulose, vinyl butyral, and the like are preferable from the viewpoint of controlling the glass transition temperature Tg of the green chip to 40 ° C. or lower.

  Moreover, the organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, toluene, and the like depending on the method to be used such as a printing method or a sheet method.

  The dielectric layer paste may contain additives selected from various dispersants, antistatic agents, dielectrics, glass frit, insulators, and the like, if necessary.

  The organic binder is contained in an amount of preferably 4 to 6.5 parts by mass, more preferably 4 to 6 parts by mass with respect to 100 parts by mass of the ceramic powder. If the amount of the binder resin added is too small, sufficient strength and adhesiveness tend not to be obtained in sheet molding / processing, and if too large, the strength of the sheet tends to be too high.

  The weight ratio of the plasticizer in the dielectric layer paste when the plasticizer is blended is preferably 20 with respect to 100 parts by weight of the organic binder from the viewpoint of controlling the glass transition temperature Tg of the green chip to 40 ° C. or less. -70 parts by weight. Moreover, when there is too little plasticizer, there exists a tendency for the elongation and flexibility of a green sheet to deteriorate, and when too much, a plasticizer oozes out on the green sheet surface, and handling is difficult.

  The green sheet is obtained by forming a dielectric layer paste into a sheet shape. This paste can be obtained by mixing and dispersing each of the above components with a ball mill, a bead mill or the like.

Internal Electrode Pattern Layer The internal electrode layer 12 in FIG. 1 is obtained by firing the internal electrode pattern layer 12a shown in FIG. 2b, and the internal electrode pattern layer is obtained by molding an internal electrode layer paste.

  First, an internal electrode layer paste is prepared. The internal electrode layer paste is composed of an organic solvent-based paste obtained by kneading a conductor powder and an organic vehicle.

  The conductor powder contained in the internal electrode pattern layer 12a in the present embodiment is not particularly limited, but a base metal can be used because the constituent material of the dielectric layer 10 has reduction resistance. As the base metal used as the conductor powder, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more.

  The organic vehicle contains an organic binder and a solvent as main components, and includes a plasticizer and the like.

  The organic binder in the present embodiment is not particularly limited, but ethyl cellulose, butyral, acrylic and the like are preferable.

  The solvent is not particularly limited, but when butyral resin is used for the ceramic green sheet, α-terpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, dihydroter Examples include pinyl acetate, dihydroterpinyl methyl ether, terpinyl methyl ether, l-dihydrocarbyl acetate and the like.

  The total content of the organic binder is preferably more than 2 parts by weight and less than 9 parts by weight, more preferably 3 to 8 parts by weight with respect to 100 parts by weight of the conductor powder.

  By setting the organic binder within this range, the viscosity of the internal electrode paste can be made suitable for screen printing, and the binder removal property can be improved.

  The content of the plasticizer is preferably 10 to 150 parts by weight, more preferably 25 to 100 parts by weight with respect to 100 parts by weight of the organic binder.

  The solvent is contained in the internal electrode paste in an amount of preferably 50 to 150 parts by weight, more preferably 80 to 100 parts by weight with respect to 100 parts by weight of the conductor powder.

  If the amount of the solvent is too small, the paste viscosity becomes too high, and if it is too much, the paste viscosity becomes too low.

  The internal electrode pattern layer is obtained by forming the internal electrode layer paste into a sheet shape. This paste can be obtained by mixing and dispersing each of the above components with a ball mill, a bead mill or the like.

Green chip A green chip is obtained by forming the above-described dielectric layer paste and internal electrode layer paste as follows.

(Formation of green sheet 10a)
As shown in FIG. 2a, a dielectric layer paste is applied to the surface of a support sheet 20 made of, for example, a PET film by, for example, a doctor blade method to form a green sheet 10a. The green sheet 10a becomes the dielectric layer 10 shown in FIG. 1 after firing.

(Formation of internal electrode layer 12a)
Next, as shown in FIG. 2b, the internal electrode layer paste is applied to the surface of the green sheet 10a formed on the support sheet 20 in a predetermined pattern to form the internal electrode layer 12a. The internal electrode layer 12a becomes the internal electrode layer 12 shown in FIG.

  The method for forming the internal electrode layer 12a in FIG. 2b is not particularly limited as long as the layer can be formed uniformly. For example, a thick film forming method such as a screen printing method or a gravure printing method using an electrode layer paste, or Examples are thin film methods such as vapor deposition and sputtering.

  As shown in FIG. 2c, the green sheet 10a on which the internal electrode layer 12a is formed is peeled off from the support sheet 20 and sequentially laminated to form a laminate 24.

(Cutting of laminated body 24)
A plurality of green chips 42 are formed by cutting the laminate 24 into a lattice shape.

(Glass transition temperature Tg)
As described above, the glass transition temperature of the green chip in the present embodiment can be controlled by the plasticizer content of the dielectric ceramic green sheet of the green chip.

  In this embodiment, the green chip may be solidified and dried or may not be solidified and dried. However, by solidifying and drying, voids are generated due to the removal of the plasticizer. Especially in the case of wet polishing, the polishing liquid penetrates due to the voids, the resin swells and induces structural defects. Tend to deteriorate. Therefore, it is preferable to proceed the process without performing the solidification drying process.

Polishing Process FIG. 3A is a perspective view of the green chip 42. As shown in FIG. 3 (A), the green chip obtained after cutting often has a rectangular parallelepiped shape, and sharp edges and ridge lines due to the cutting process are generated at the ends. For this reason, in order to suppress the defect | deletion (chip, chipping, etc.) of components resulting from the collision of components in a manufacturing process, grinding | polishing is normally performed as a chamfer with respect to a green chip.

  First, the polishing method is not particularly limited as long as the temperature at the time of polishing can be controlled, and barrel polishing, blast polishing, and cutting polishing are exemplified. Among these, barrel polishing is preferable. The barrel polishing includes wet barrel polishing or dry barrel polishing, and dry barrel polishing is more preferable.

  In addition, wet barrel polishing refers to an object to be polished, a polishing liquid such as water or an organic solvent, and a medium such as a grinding stone as necessary in a fixed ratio, and performs a motion such as rotation. This is a method of applying and polishing. Thereby, a target object can be grind | polished because a target object and / or a target object and a medium mutually rub against each other.

  On the other hand, dry barrel polishing is a method of polishing an object without using a polishing liquid. By using dry barrel polishing, since a polishing liquid such as water is not used, elution of Ba ions can be prevented or a simpler mechanism than wet processing can be performed. Further, in contrast to wet barrel polishing in which the lower limit of Tc is determined by the freezing point of the polishing liquid, dry barrel polishing without using the polishing liquid can be set without limitation to the lower limit of Tc because there is no polishing liquid.

  The present embodiment is characterized in that the temperature Tc of the green chip in the polishing process is controlled within a predetermined range. Specifically, Tc is 25 ° C. or more, preferably 30 ° C. or more, more preferably 35 to 40 ° C. lower than Tg. Further, preferably, the temperature Tc of the green chip in the polishing step is 10 ° C. or lower, more preferably −40 to 10 ° C.

  Examples of the method for controlling the polishing step to such a temperature include a method of controlling the temperature in the container by immersing the barrel container in a thermostatic bath, and a method of controlling the air conditioning of the room where the barrel container exists. . For wet barrel polishing, for example, a method of controlling the temperature of the polishing liquid by connecting the barrel container and an external thermostatic bath with a hose and circulating the polishing liquid, and the polishing liquid in the barrel container at regular intervals. And a method of controlling the temperature of the polishing liquid.

  Furthermore, in the case of dry barrel polishing, for example, a method of blowing carbon dioxide gas at a predetermined temperature to the outside or inside of the barrel container can be mentioned.

  By controlling the barrel polishing conditions in this way, softening of the green chip containing the plasticizer can be controlled, and the green chip 42 before barrel polishing shown in FIGS. 3 (A) and 3 (B) can be efficiently obtained. After barrel polishing, as shown in FIGS. 4 (A) and 4 (B), the corners and ridges can be rounded to form the green chip 42a. Furthermore, by using the green chip thus polished, it is possible to provide an electronic component having excellent electrical characteristics such as a withstand voltage failure rate.

The green chip 42 after the green chip firing barrel polishing step is washed by spraying water or high-pressure air and dried. The capacitor element body 4 shown in FIG. 1 is obtained by performing a binder removal process, a firing process, and an annealing process performed as necessary on the dried green chip.

Formation of External Electrode Capacitor element 4 obtained in this manner is subjected to end face polishing by sandblasting or the like, and external electrode paste is baked to form external electrodes 6 and 8. The conductive material contained in the external electrodes 6 and 8 is not particularly limited, but in the present embodiment, inexpensive Ni, Cu, and alloys thereof can be used. Further, the thicknesses of the external electrodes 6 and 8 may be appropriately determined according to the use and the like, but it is usually preferably about 10 to 50 μm.

  Then, if necessary, a plating process is performed on the external electrodes 6 and 8. The external electrode paste may be prepared in the same manner as the above internal electrode pattern layer paste. Since the above-described barrel polishing can sufficiently secure the coating thickness of the paste at the corner portion of the capacitor element 4, cracks during baking of the external electrodes can also be suppressed.

  The multilayer ceramic capacitor manufactured by the method according to this embodiment is mounted on a printed circuit board by soldering or the like, and used for various electronic devices.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the present invention is not limited to a multilayer ceramic capacitor, and may be any electronic component that will process a green chip in the manufacturing process.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Sample 1
(Preparation of dielectric layer paste)
BaTiO ₃ is prepared as a main component raw material, and the following first to fourth subcomponents are added, wet mixed and pulverized by a ball mill to form a slurry, and after the slurry is dried, calcined and pulverized, the dielectric is obtained. A body porcelain composition powder was obtained. In addition, the addition amount of each subcomponent is an addition amount in terms of each oxide with respect to 100 mol of the main component.

MgO (first subcomponent): 1.2 mol,
(Ba, Ca) SiO ₃ (second subcomponent): 0.75 mol,
V ₂ O ₅ (third subcomponent): 0.03 mol,
MnO (fourth subcomponent): 0.1 mol,

  And 100 parts by weight of the dielectric ceramic composition powder obtained above, 6 parts by weight of polyvinyl butyral as a binder resin, 40 phr of dioctyl phthalate (DOP) as a plasticizer, and 60 parts by weight of methyl ethyl ketone Then, 40 parts by weight of ethanol and 20 parts by weight of toluene were mixed with a ball mill to obtain a paste, thereby obtaining a green sheet slurry. “Phr” is a weight ratio with respect to 100 parts by weight of the binder resin.

(Preparation of internal electrode layer paste)
Next, 44.6 parts by weight of Ni particles, 52 parts by weight of terpineol, 3 parts by weight of ethyl cellulose, and 0.4 parts by weight of benzotriazole are kneaded with three rolls to form a slurry for an internal electrode layer paste. Obtained.

(Production of multilayer ceramic capacitor)
A multilayer ceramic capacitor 1 shown in FIG. 1 was produced using the pastes prepared above as follows.

  First, a green sheet was formed on a PET film using the obtained dielectric layer paste. After the internal electrode layer paste was printed thereon, the sheet was peeled from the PET film. Subsequently, these green sheets and protective green sheets (not printed with the internal electrode layer paste) were laminated and pressure-bonded to obtain a laminate.

  Next, the laminate was cut into a size of 1.6 mm × 0.8 mm × 0.8 mm to obtain a green chip.

  The glass transition temperature Tg of the green chip was 20 ° C. This glass transition temperature was adjusted by adjusting the amount of the plasticizer added in the dielectric layer paste to 40 phr. The glass transition temperature Tg was measured with a viscoelastic spectrometer (DMS) [EXSTAR 6000 SERIES-DMS 6100 (manufactured by SII Nanotechnology)].

(Barrel polishing)
Next, the obtained green chips are divided into 6 groups of 10,000, and the temperature Tc of the green chip in the polishing process is controlled to 40 ° C., 20 ° C., 5 ° C., 0 ° C., −10 ° C., −20 ° C., respectively. Polishing was performed for 360 minutes. In addition, when Tc was 40 ° C., 20 ° C., and 5 ° C., wet barrel polishing was performed, and when Tc was −20 ° C., dry barrel polishing was performed.

First, in wet barrel polishing, 500 g of green chips, 1000 g of media 56, and 1.6 L of ion-exchanged water were put into a 2 L (liter) barrel container. Further, the shape of the media was substantially spherical, and the material was a ceramic ball mainly composed of alumina and silica, and the size was about 2 mm.
In addition, temperature control was performed by immersing a barrel tank in a thermostat.

In dry barrel polishing, 500 g of green chips and 1000 g of media 56 were put in a 2 L barrel container. Further, the shape of the media was substantially spherical, the material was a ceramic ball mainly composed of alumina and silica, and the size was about 2 mm.
The control of the temperature of the green chip in the polishing step was performed by blowing -40 ℃ of CO ₂ gas.

  The non-lamination (non-adhesion defect) defect rate and corner R value of the solidified and dried green chip were measured by the following methods.

(Non-lamination failure rate)
First, 50 green chips were embedded in a two-component curable epoxy resin so that the side surfaces of the dielectric layer and the internal electrode layer were exposed, and then the two-component curable epoxy resin was cured. Next, the green chip embedded in the epoxy resin was polished to a depth of 0.4 mm using sandpaper. The sandpaper was polished by using # 400 sandpaper, # 800 sandpaper, # 1000 sandpaper, and # 2000 sandpaper in this order. Next, the sandpaper polished surface was subjected to mirror polishing using diamond paste. Then, using an optical microscope, the polished surface was observed at an enlargement magnification of 400 times to check for non-lamination. As a result of observation with an optical microscope, the ratio of green chips in which non-lamination had occurred relative to all measurement samples was defined as the non-lamination defect rate.

(Corner R value)
Regarding the shape of the corner portion after polishing, the green chip 42a after polishing shown in FIG. 4 (A) was cut along the IVB-IVB line in FIG. 4 (A) for 30 green chips. Then, the cross section (FIG. 4B) is polished to the center of the green chip, the shape of the corner V (FIGS. 4 and 5) is observed with a microscope, and the R value defined below is obtained, The average value was calculated.

  That is, in FIG. 5, when a line perpendicular to the stacking direction is drawn from the apex of the green chip 42 before polishing, the length from the intersection of the line and the ridge line of the green chip 42a after polishing to the apex is expressed as X It was. Similarly, when a line parallel to the stacking direction was drawn from the apex, the length from the intersection of the line and the edge of the green chip 42a after polishing to the apex was defined as Y. R is an average value of X and Y, that is, R = (X + Y) / 2.

  Hereinafter, although the firing process of the green chip and the formation process of the external electrode will be described, the firing and formation of the external electrode were performed by the same method in any green chip of Tc. The results are shown in Tables 2 and 3.

(Green chip firing process)
The green chip 42 after barrel polishing was washed with water and dried. The dried green chip was subjected to binder removal processing, firing and annealing under the following conditions to obtain a capacitor element body 4.
Debinder treatment condition temperature increase rate: 32.5 ° C./hour,
Holding temperature: 260 ° C.
Temperature holding time: 8 hours,
Atmosphere: in the air.
Firing condition heating rate: 200 ° C./hour,
Holding temperature: 1260-1280 ° C
Temperature holding time: 2 hours,
Cooling rate: 200 ° C./hour,
Atmospheric gas: humidified N ₂ + H ₂ mixed gas (oxygen partial pressure: 10 ⁻⁷ Pa).
Annealing condition heating rate: 200 ° C./hour,
Holding temperature: 1050 ° C.
Temperature holding time: 2 hours,
Cooling rate: 200 ° C./hour,
Atmospheric gas: humidified N ₂ gas (oxygen partial pressure: 1.01 Pa).

  Note that a wetter with a water temperature of 20 ° C. was used for humidifying the atmospheric gas during firing and annealing.

(Formation of external electrodes)
The capacitor element body 4 thus obtained was subjected to end surface polishing by sandblasting or the like, and Cu was applied as an external electrode to form external electrodes 6 and 8.

  The size of the obtained capacitor sample was 1.6 mm × 0.8 mm × 0.8 mm, the number of dielectric layers sandwiched between the internal electrode layers was 380, and the thickness of the dielectric layer per layer ( The interlayer thickness was 1.3 μm, and the thickness of the internal electrode layer was 0.9 μm.

  Subsequently, the chip defect rate and the withstand voltage failure rate of the capacitor samples were evaluated by the methods described below. The results are shown in Table 3.

(Defect rate)
For 10,000 capacitor samples of each Tc, four surfaces on which the counter electrode was not exposed were observed with a stereomicroscope to inspect for structural defects (chips, chipping, etc.). The smaller the defective chip rate, the better. The target value was 0.4%.

(Voltage failure rate)
For 10,000 capacitor samples of each Tc, the resistivity when a voltage of 150 V was applied was obtained, and the ratio of the number of capacitor samples having a resistivity of 10 ⁶ Ω or less was defined as a withstand voltage (withstand voltage) defect rate. The target value was 0.2%.

Sample 2-6
A green chip and a capacitor sample were produced in the same manner as in Sample 1 except that the glass transition temperature was changed as shown in Table 1 by changing the plasticizer content contained in the dielectric ceramic green sheet. The rate was measured. The results are shown in Table 1, Table 2, and FIG.
(Glass transition temperature Tg)
From Table 2 and FIG. 6, when Tg was larger than 40 degreeC, it turned out that there exists a tendency for the non-lamination failure rate to deteriorate. Since the deterioration of the non-laminating defect rate is considered to cause the deterioration of the electric characteristics of the capacitor, it is considered that Tg needs to be 40 ° C. or lower in order to improve the electric characteristics of the capacitor sample. .
Next, Tc was adjusted for Sample 1, Sample 2, Sample 3, and Sample 4 with Tg of 40 ° C. or less, and the corner R value, chip defect rate, and withstand voltage failure rate were measured. The results are shown in Tables 3-6.

(Tg-Tc)
Table 7 shows that for each sample having a withstand voltage failure rate of 0.2% or less among the samples shown in Tables 3 to 6, the chip failure rate or the corner R value with respect to Tg-Tc is set to the size of Tg-Tc. It is rearranged along. From this result, as shown in FIG. 7, when Tg−Tc is 25 ° C. or higher, the corner R value and chip defect rate are better and the polishing efficiency is higher than when it is lower than 25 ° C. all right.

(Tc)
From the results of Tables 3 to 6, it was found that when the Tg-Tc is 25 ° C. or more and the Tc is 10 ° C. or less, the corner R value and the chip defect rate are further improved.

2 ... Multilayer ceramic capacitor 4 ... Capacitor element body 6, 8 ... External electrode 10 ... Dielectric layer 10a ... Inner green sheet 11a ... Outer green sheet 12 ... Internal electrode layer 12a ... Internal electrode pattern layer 20 ... Support sheet 24 ... Laminate 42 ... Green chip 42a ... Green chip

Claims (6)

Preparing an unfired green chip containing a plasticizer;
Polishing the green chip;
Have
The glass transition temperature Tg of the green chip immediately before the polishing step is 40 ° C. or less,
A method of manufacturing an electronic component, wherein the temperature Tc of the green chip in the polishing step is 25 ° C. or more lower than the glass transition temperature Tg.   The method of manufacturing an electronic component according to claim 1, wherein the green chip is polished by dry barrel polishing.   3. The method of manufacturing an electronic component according to claim 1, wherein the temperature Tc of the green chip in the polishing step is 30 ° C. or more lower than the glass transition temperature Tg.   The method for manufacturing an electronic component according to claim 1, wherein the temperature Tc of the green chip in the polishing step is 10 ° C. or less.   The method for manufacturing an electronic component according to claim 1, further comprising a step of firing the green chip after the polishing step.   The method for producing an electronic component according to claim 1, wherein the plasticizer is at least one selected from dioctyl phthalate, dibutyl phthalate, and butyl benzyl phthalate.

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