JP2015133360A - Method for manufacturing multilayer ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer ceramic capacitor which suppresses a decrease and an increase in a coverage of inner electrodes and achieves high capacity and excellent pressure resistance and reliability, in a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor and the like.SOLUTION: The present invention is a method for manufacturing a multilayer ceramic electronic component having inner electrodes configured by a material made of at least conductive powder and oxide powder, the method including a step of baking an unbaked ceramic body. After holding the ceramic body at at least one temperature (first holding temperature) between 600°C to 700°C in the baking step, the temperature is increased at a speed of 20°C/min or more within a temperature range of at least 100°C or more between 600°C to 900°C, and followed by being held at at least one temperature (second holding temperature) between 800°C to 900°C.

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component, for example, a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor, a multilayer ceramic inductor, a multilayer ceramic varistor, and a multilayer ceramic thermistor.

In general, a multilayer ceramic electronic component such as a multilayer ceramic capacitor is manufactured by laminating and pressing a ceramic green sheet on which an internal electrode material is formed, and firing it. In the firing step in the method of manufacturing the multilayer ceramic electronic component, temperature control is performed such that the temperature is raised to the maximum temperature at which the internal electrode material and the ceramic are sintered, held at the maximum temperature, and then lowered. In such temperature control, the temperature is raised at an optimum rate from the normal temperature to the maximum temperature in consideration of both the sintering of the internal electrode material and the sintering of the ceramic.
On the other hand, in recent years, cracks and delamination have become a problem after firing as the multilayer ceramic electronic components are made thin. These problems are caused by a difference in shrinkage ratio due to firing of the ceramic and the internal electrode material due to the thinning of the internal electrode and the ceramic layer and an increase in the number of laminated layers.

  Therefore, in the firing step in the method of manufacturing a multilayer ceramic electronic component described in Patent Document 1, the temperature is increased at a rate of 50 ° C. or less per hour between the shrinkage start temperature of the metal powder layer and the shrinkage start temperature of the ceramic powder layer. By doing so, delamination is suppressed because sintering of the internal electrode proceeds slowly.

  Further, in the firing step in the method of manufacturing the multilayer ceramic electronic component described in Patent Document 2, when the temperature rises until the maximum temperature in the firing step is reached, the internal electrode material rapidly shrinks between a plurality of temperature ranges. By holding each at a predetermined temperature for a predetermined time in each case, the internal electrode material does not shrink rapidly, the consistency of shrinkage with the ceramic body can be taken, and the occurrence of structural defects such as cracks and delamination is suppressed. .

Japanese Patent Laid-Open No. 10-303063 JP 2004-0479902 A

However, in the firing step in the method of manufacturing a multilayer ceramic electronic component disclosed in Patent Document 1 and Patent Document 2, it is added for suppressing the sintering of metal powder in a moderate temperature rising process in the range of 600 ° C to 900 ° C. Most of the ceramic powder thus discharged is discharged out of the internal electrode layer, so that a sufficient sintering suppression effect cannot be obtained, and cracks are caused due to a decrease in the coverage or thickness of the internal electrode. As a result, there has been a problem that the capacity, pressure resistance and reliability of the multilayer ceramic capacitor are lowered.
The same applies to a metal powder provided with a metal oxide coating layer as a sintering inhibitor for metal powder, and most of the metal oxide components are discharged out of the internal electrode layer during a gradual temperature rise process. There was a problem that the sintering suppressing effect could not be sufficiently obtained.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multilayer ceramic capacitor excellent in high capacity, high withstand voltage, and high reliability in a method of manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor by suppressing a decrease in the coverage and thickness of the internal electrode. Is to provide.

A method for manufacturing a multilayer ceramic electronic component according to the present invention includes a step of firing an unfired ceramic body, and includes a multilayer ceramic electronic component having an internal electrode made of a material composed of at least a conductive powder and an oxide powder. In the production method, after holding at least one temperature between 600 ° C. and 700 ° C. in the baking step, at a rate of 20 ° C./min or more in a temperature range of at least 100 ° C. between 600 ° C. and 900 ° C. A method for producing a multilayer ceramic electronic component, wherein the temperature is raised and further maintained at at least one temperature between 800 ° C. and 900 ° C.
In the method for producing a multilayer ceramic electronic component according to the present invention, the conductive powder constituting the internal electrode contains at least one selected from the group of substances consisting of Ni and Cu, or at least one selected from the group of substances. It is preferable that it contains an alloy.
Furthermore, in the method for producing a multilayer ceramic electronic component according to the present invention, the oxide constituting the internal electrode is at least one metal oxide or composite metal oxide composed of a base element rather than the main component element of the conductive powder. It is preferable that
Further, the method for producing a multilayer ceramic electronic component according to the present invention is a particle size ratio of the specific surface area diameter of the conductive powder constituting the internal electrode and the specific surface area diameter of the ceramic powder, (ceramic powder specific surface area diameter) / The (conductive powder specific surface area diameter) is preferably 0.01 or more and 0.20 or less.
Furthermore, in the method for manufacturing a multilayer ceramic electronic component according to the present invention, the oxide powder constituting the internal electrode is preferably the same component as the main component of the ceramic layer.
In the method for manufacturing a multilayer ceramic electronic component according to the present invention, the oxide powder constituting the internal electrode is preferably an oxide having a perovskite structure.
Furthermore, in the method for manufacturing a multilayer ceramic electronic component according to the present invention, the main component of the oxide powder constituting the internal electrode is preferably barium titanate.

According to the method of manufacturing a multilayer ceramic electronic component according to the present invention, the multilayer ceramic electronic including the step of firing an unfired ceramic body and having an internal electrode composed of at least a material composed of conductive powder and oxide powder In the component manufacturing method, after holding at least one temperature between 600 ° C. and 700 ° C. in the firing step, at a temperature range of at least 100 ° C. between 600 ° C. and 900 ° C., 20 ° C./min or more Since the temperature is increased at a rate and further maintained at at least one temperature between 800 ° C. and 900 ° C., the ceramic component is effectively incorporated into the triple point of the densified metal grain, and the high temperature range after densification Thus, it is possible to form an internal electrode in which cracks due to a decrease in coverage or a thickness are unlikely to occur. As a result, for example, it is possible to increase the capacity of the multilayer ceramic capacitor and to increase the withstand voltage and reliability.
Moreover, according to the method for manufacturing a multilayer ceramic electronic component according to the present invention, the oxide constituting the internal electrode is at least one metal oxide or composite metal composed of an element lower than the main component element of the conductive powder. In the case of an oxide, the ceramic component can be effectively incorporated into the triple point of the metal grain.
Furthermore, according to the method for producing a multilayer ceramic electronic component according to the present invention, the specific surface area diameter of the ceramic powder is a particle diameter ratio between the specific surface area diameter of the conductive powder and the specific surface area diameter of the ceramic powder. ) / (Conductive powder specific surface area diameter) is 0.01 or more and 0.20 or less, the ceramic component can be more effectively incorporated into the triple point of the metal grain.
Further, according to the method of manufacturing a multilayer ceramic electronic component according to the present invention, when the oxide powder constituting the internal electrode is the same component as the main component of the ceramic layer, sintering between the internal electrode and the ceramic layer is performed. The difference in shrinkage behavior at the time can be suppressed.
Furthermore, according to the method for producing a multilayer ceramic electronic component according to the present invention, when the oxide powder constituting the internal electrode is an oxide having a perovskite structure, particularly, barium titanate, the multilayer ceramic electronic component having a high dielectric constant. Can be obtained.

  According to the present invention, in a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor, it is possible to obtain a multilayer ceramic capacitor that suppresses a decrease in the coverage and thickness of an internal electrode and has high capacity, excellent pressure resistance and reliability. Can do.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

1 is a vertical sectional view showing an embodiment of a multilayer ceramic capacitor to which the present invention is applied.

1. 1 is a vertical sectional view showing an embodiment of a multilayer ceramic capacitor to which the present invention is applied. A multilayer ceramic capacitor 10 shown in FIG. 1 includes a rectangular parallelepiped ceramic element 12. The ceramic element 12 includes a number of ceramic layers 14 made of a dielectric. These ceramic layers 14 are laminated.
There are no restrictions on the densified state and grain size of the ceramic layer 14.

  Internal electrodes 16 a and 16 b using Ni or Cu are alternately formed between the ceramic layers 14. In this case, the internal electrode 16 a is formed with one end extending to one end of the ceramic element 12, and the internal electrode 16 b is formed with one end extending to the other end of the ceramic element 12. The internal electrodes 16 a and 16 b are formed so that the intermediate portion and the other end portion overlap with each other with the ceramic layer 14 interposed therebetween.

  On one end surface of the ceramic element 12, for example, an external electrode 18a using Cu is formed so as to be connected to the internal electrode 16a. Similarly, an external electrode 18b using, for example, Cu is formed on the other end surface of the ceramic element 12 so as to be connected to the internal electrode 16b. Note that a Ni plating layer and a Sn plating layer may be formed on the surface sides of the external electrodes 18a and 18b.

2. Manufacturing Method of Multilayer Ceramic Capacitor Next, a manufacturing method of the multilayer ceramic capacitor 10 shown in FIG. 1 will be described.

  35 parts by weight of Ni powder or Cu powder having a specific surface area diameter (BET diameter) of 100 nm to 300 nm, which is a conductive powder, and 3 weights of oxide powder having a perovskite structure having a specific surface area diameter (BET diameter) of 4 nm to 100 nm, which is a ceramic powder. Part by weight, 5 parts by weight of a polymeric dispersant, and 57 parts by weight of an organic vehicle composed of ethyl cellulose resin and dihydroterpineol acetate, and a conductive paste is obtained with a pot mill. The specific surface area diameter (BET diameter) is calculated by the BET method.

  The conductive powder constituting the internal electrode preferably includes an alloy containing at least one selected from the group of substances consisting of Ni or Cu or at least one selected from the group of substances consisting of Ni or Cu. is there. Further, the metal oxide constituting the internal electrodes 16a and 16b is a base element (Mg, Al, Cr, Ni, Sn, Ba, Ti, Y, Dy, Gd, Mn, V, etc.) , Zr) is preferably at least one metal oxide or composite metal oxide.

  Moreover, it is preferable that the oxide powder which is a ceramic powder used for obtaining the conductive paste is the same component as the main component of the ceramic green sheet for forming the ceramic layer 14 described later. Furthermore, the oxide powder, which is a ceramic powder used to obtain a conductive paste, is preferably a perovskite oxide, and particularly preferably barium titanate.

  Further, (ceramic powder specific surface area diameter) / (conductive powder specific surface area diameter), which is a particle diameter ratio between the specific surface area diameter of the conductive powder and the specific surface area diameter of the ceramic powder, is 0.01 or more and 0.20 or less. If it is within the range, it is more preferable.

  Subsequently, a ceramic material mainly composed of barium titanate having a specific surface area diameter (BET diameter) of 200 nm, an organic binder, an organic solvent, a plasticizer, and a dispersant are mixed at a predetermined ratio, and wet using a ball mill. Dispersion treatment is performed to obtain a ceramic slurry. Next, this ceramic slurry is formed on a PET (polyethylene terephthalate) film using a doctor blade method so that the thickness of the ceramic layer 14 after drying is 2.0 μm, thereby obtaining a ceramic green sheet. .

  Then, on the above-described ceramic green sheet, the dried internal electrodes 16a and 16b have a pattern in which the planar dimension of the ceramic element 12 after cutting and firing obtained later is 1.0 mm × 0.5 mm. The conductive paste described above is printed by a screen printer so that the thickness is 0.5 μm, and conductive coatings to be the internal electrodes 16a and 16b are formed.

  Subsequently, after the ceramic green sheets on which the conductive coating film is printed are peeled off from the PET film, 200 ceramic green sheets are stacked to produce a mother ceramic body. Then, the mother ceramic body is placed in a predetermined mold and pressed in the stacking direction.

  Next, the pressed mother ceramic body is cut into a predetermined size to obtain a capacitor body as a chip-shaped unfired ceramic body to be an individual multilayer ceramic capacitor.

  Then, this unfired capacitor body is degreased at a temperature of 280 ° C. for 10 hours in nitrogen. And the ceramic element 12 and the internal electrodes 16a and 16b are formed by baking the degreased unfired capacitor body in a firing furnace.

In this case, the atmosphere in the firing furnace is adjusted to be an N ₂ —H ₂ O—H ₂ mixed atmosphere in which the oxygen partial pressure is 10 ⁻¹³ MPa to 10 ⁻²⁰ MPa. Moreover, the firing profile is as follows. That is, first, the temperature is raised from room temperature to 600 ° C. to 700 ° C. at a rate of 3.3 ° C./min, and at a predetermined temperature ± 5 ° C. (first holding temperature) between 600 ° C. and 700 ° C. reached 2 hours. Retained. Next, in a temperature range of at least 100 ° C. between 600 ° C. and 900 ° C., the temperature is increased at a rate of 20 ° C./min or more (120 ° C./hour) and reaches a predetermined temperature between 800 ° C. and 900 ° C. Hold at ± 5 ° C. (second holding temperature) for 2 hours. Next, it is adjusted to an N ₂ —H ₂ O—H ₂ mixed atmosphere in which the oxygen partial pressure is 10 ⁻⁸ MPa to 10 ⁻⁹ MPa, and rises to 1210 ° C. (third holding temperature) at a rate of 8 ° C./min. Warm and hold for 1 hour. And after hold | maintaining at 3rd holding temperature, it cools to normal temperature with the temperature-fall rate of 3.3 degree-C / min.

  And after hold | maintaining at 3rd holding temperature, it cools to normal temperature with the temperature-fall rate of 3.3 degree-C / min.

  Then, external electrodes 18a and 18b are formed on both end faces of the ceramic element 12 by applying and baking Cu. For example, Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like can be used for the external electrodes 18a and 18b. Further, a Ni plating layer and a Sn plating layer may be formed on the surface side of the external electrodes 18a and 18b.

  The multilayer ceramic capacitor 10 is manufactured as described above.

  According to the method for manufacturing a multilayer ceramic capacitor according to the present embodiment, by increasing the rate of temperature increase in the 600 ° C. to 900 ° C. region between the first holding temperature and the second holding temperature, Sintering (densification) of the metal particles can proceed at a high speed (short time). As a result, the metal oxide particles can be effectively incorporated into the triple point of the densified metal grains in the process of rapid densification of the metal particles. The metal oxide growth located by the metal oxide particles located at the triple point of the metal grains and the metal oxide particle constituent elements diffused to the grain boundary connected to the triple point makes the coverage in a high temperature range after densification. The internal electrodes 16a and 16b that are less likely to generate cracks due to reduction or weighting can be formed. As a result, it is possible to manufacture the monolithic ceramic capacitor 10 that achieves high capacity and has excellent pressure resistance and reliability.

In the above-described firing process of the unfired capacitor body, when a binder or a dispersant is used to form the ceramic layer 14 and the internal electrodes 16a and 16b, the temperature is between the first holding temperature and the second holding temperature. When the temperature raising rate in the 600 ° C. to 900 ° C. region is increased, structural defects due to the rapid combustion gas of the remaining organic matter may occur.
Then, like the manufacturing method of the multilayer ceramic capacitor according to the present embodiment, by holding at a predetermined temperature (first holding temperature) between 600 ° C. and 700 ° C., from the first holding temperature to the second holding temperature. It is necessary to degrease until a structural defect hardly occurs in the range of 600 ° C to 900 ° C. It should be noted that in order to make a structural defect difficult to occur at a temperature higher than 900 ° C., it differs depending on the size and structure of the chip.

Further, in the above-described firing process of the unfired capacitor element body, when a binder or a dispersant is used for forming the ceramic layer 14 and the internal electrodes 16a and 16b, a predetermined temperature between 600 ° C. and 700 ° C. (first Degreasing cannot be performed sufficiently only by holding at the holding temperature), and structural defects due to the rapid burning gas of the remaining organic matter may occur in a temperature range higher than 900 ° C.
Therefore, as in the method for manufacturing a multilayer ceramic capacitor according to the present embodiment, structural defects occur at a temperature higher than 900 ° C. by holding at a predetermined temperature (second holding temperature) between 800 ° C. and 900 ° C. It is necessary to degrease until it becomes difficult. It should be noted that in order to make a structural defect difficult to occur at a temperature higher than 900 ° C., it differs depending on the size and structure of the chip.

  Furthermore, metal oxide particles may not be present at all three points of the metal grains, but the larger the number, the higher the effect of suppressing grain growth. Moreover, the higher grain growth suppression effect is obtained when there is a grain boundary layer in which the metal oxide particle constituent elements are diffused. Further, the grain boundary layer in which the metal oxide particle constituent element is diffused may have a gap, but as there is no gap, a higher grain growth suppression effect is obtained. Moreover, forms other than metal oxide particles may be sufficient, for example, the form which coat | covers electroconductive powder with a metal oxide component may be sufficient.

(Experimental example)
Next, experimental examples carried out based on the present invention will be described.

(Experimental example 1)
In Experimental Example 1, in the firing treatment of the method for manufacturing a multilayer ceramic capacitor according to the present invention, the internal electrode when the holding temperature of the first holding temperature and the second holding temperature and the temperature rising rate between the holding temperatures are changed. An evaluation experiment was conducted on the coverage ratio and crack generation rate of multilayer ceramic capacitors. Therefore, a multilayer ceramic capacitor as a sample was produced as follows.

  First, 35 parts by weight of Ni powder having a specific surface area diameter (BET diameter) of 200 nm, 3 parts by weight of barium titanate powder having a specific surface area diameter (BET diameter) of 20 nm, 5 parts by weight of a polymeric dispersant, ethyl cellulose resin and dihydro The mixture was mixed with 57 parts by weight of an organic vehicle made of terpineol acetate, and a conductive paste was obtained using a pot mill.

  Then, a ceramic material mainly composed of barium titanate having a specific surface area diameter (BET diameter) of 200 nm, an organic binder, an organic solvent, a plasticizer, and a dispersant are mixed at a predetermined ratio, and wet dispersion is performed using a ball mill. Processing gave a ceramic slurry. Next, a ceramic green sheet is obtained by forming this ceramic slurry on a PET (polyethylene terephthalate) film using a doctor blade method so that the thickness of the dried ceramic layer 14 is 2.0 μm. It was.

  Subsequently, on the ceramic green sheet described above, the Ni powder after drying has a pattern in which the planar dimension of the chip-shaped laminate after cutting and firing obtained later is 1.0 mm × 0.5 mm. The conductive paste described above was printed by a screen printer so that the thickness of the used internal electrodes 16a and 16b was 0.5 μm, and a conductive coating film to be an internal electrode was formed.

  And after peeling the ceramic green sheet on which the conductive coating film was printed from the PET film, 200 ceramic green sheets were stacked, put into a predetermined mold, and pressed.

  Subsequently, the pressed multilayer body block was cut into a predetermined size, and a capacitor body as a chip-shaped unfired ceramic body to be an individual multilayer ceramic capacitor was obtained.

Then, this unfired capacitor body is degreased in nitrogen at a temperature of 280 ° C. for 10 hours, and then the atmosphere in the firing furnace is changed to N with an oxygen partial pressure of 10 ⁻¹³ MPa to 10 ⁻²⁰ MPa. It was adjusted to ₂ -H ₂ O-H ₂ mixed atmosphere. As a firing profile, first, the temperature was raised from room temperature to 600 ° C. to 750 ° C. at a rate of 3.3 ° C./min, and the predetermined temperature between 600 ° C. and 750 ° C. reached ± 5 ° C. (first holding temperature) For 2 hours. Next, the temperature is raised to a predetermined temperature between 700 ° C. and 1000 ° C. at a rate of 1 ° C. to 100 ° C./min, and the predetermined temperature between 700 ° C. and 1000 ° C. reaches ± 5 ° C. (second holding temperature). Held for hours. Next, the temperature is raised to 1210 ° C. (third holding temperature) at a rate of 8 ° C./min in an N ₂ —H ₂ O—H ₂ mixed atmosphere where the oxygen partial pressure is 10 ⁻⁸ MPa to 10 ⁻⁹ MPa. Baked with a profile that was held for 1 hour. And after hold | maintaining at 3rd holding | maintenance temperature, it cooled to normal temperature with the temperature-fall rate of 3.3 degree-C / min. Then, the external electrodes 18a and 18b are formed by applying and baking Cu on both end faces of the ceramic element 12, and the conditions of the firing profiles shown in Tables 1 and 2 are shown as No. 1-1 to No. 13-7. A sample of the multilayer ceramic capacitor 10 based on the above was prepared.

  Eight multilayer ceramic capacitors 10 are prepared for each sample for evaluating the coverage of the internal electrodes, and 100 multilayer ceramic capacitors 10 are prepared for each sample for evaluating the crack rate. It was.

  For comparison, as shown in Table 3, the multilayer ceramic capacitors obtained by firing the firing profile having no first holding temperature were assigned numbers 0-1 to 0-7, and the crack rate was evaluated. 8 samples were prepared for each sample, and 100 samples were prepared for each sample to evaluate the crack rate.

First, 8 multilayer ceramic capacitors prepared for the evaluation of the coverage of the internal electrode are peeled off at the interface between the electrode layer and the dielectric layer, and the average value of 8 of the ratio of the metal portion of the peeled surface is taken as the coverage Calculated. In the coverage judgment, less than 65% was evaluated as “x (defect)”, 65% or more and less than 75% as “◯ (good)”, and 75% or more as “◎ (excellent)”.
In addition, the crack rate of multilayer ceramic capacitors prepared for evaluation of crack rate is determined by the appearance of cracks when structural defects are observed by external observation with an optical microscope and nondestructive internal observation with an ultrasonic microscope. As calculated. In the case of crack determination, the case where no crack occurred was set as “◯ (good)”, and the case where a crack occurred was set as “x (defective)”.
The evaluation results obtained by the above evaluation experiment are shown in Tables 1 to 3.

  First, from the results shown in Tables 1 and 2, in Nos. 1-1 to 11-7, the rate of temperature increase between the first holding temperature and the second holding temperature is 1 to 10 ° C./min. In comparison, it can be seen that the coverage of the internal electrode was significantly improved under the condition of the temperature rising rate of 20 ° C./min or more. Moreover, the tendency which the coverage of an internal electrode further improved was recognized, so that the temperature increase rate was raised.

  From the above, it is effective for improving the electrode coverage of the multilayer ceramic capacitor that the temperature rising rate in the 600 ° C. to 900 ° C. region between the first holding temperature and the second holding temperature is 20 ° C./min or more. Was recognized.

  That is, by increasing the heating rate between 600 ° C. and 900 ° C., which is between the first holding temperature and the second holding temperature, the speed at which the sintering (densification) of the metal particles in the internal electrode is fast (short) Time). Therefore, the metal oxide particles can be effectively taken into the triple point of the densified metal grains on the assumption that the metal particles are rapidly densified. Then, the metal oxide particles located at the triple point of the metal grains and the metal oxide particle constituent elements diffused to the grain boundary connected to the triple point are used to suppress the growth of the metal grains. A decrease in electrode coverage can be suppressed.

  Also, the first holding temperature is 600 ° C., the second holding temperature is 800 ° C., numbers 1-5 to 1-7, the first holding temperature is 600 ° C., and the second holding temperature is 900 ° C. No. 2-5 to No. 2-7, the first holding temperature is 650 ° C., the second holding temperature is 800 ° C., the numbers 3-5 to 3-7, the first holding temperature is 650 ° C., 2 No. 5-5 to No. 5-7 with a holding temperature of 850 ° C. No. 6-5 to No. 6-7 with a first holding temperature of 650 ° C. and a second holding temperature of 900 ° C. No. 8-5 to No. 8-7 in which the temperature is 700 ° C. and the second holding temperature is 800 ° C. No. 9-5 in which the first holding temperature is 700 ° C. and the second holding temperature is 850 ° C. No. 9-7 and No. 10-5 to No. 10 in which the first holding temperature is 700 ° C. and the second holding temperature is 900 ° C. 7 is at least one temperature with a first holding temperature between 600 ° C. and 700 ° C., and at least one temperature with a second holding temperature between 800 ° C. and 900 ° C. Since the temperature was raised at a rate of 20 ° C. or higher in a temperature range of at least 100 ° C. between the temperatures, the coverage ratio was 65% or higher, and good results were obtained.

  On the other hand, No. 4-5 to No. 4-7 have a second holding temperature of 700 ° C., No. 7-5 to No. 7-7 have a second holding temperature of 750 ° C., No. 11-5 to No. 11− No. 7 has a first holding temperature of 500, and No. 12-5 to No. 12-7 have a second holding temperature of 1000 ° C., so the crack judgment is “x (defect)”. Moreover, since the 1st holding temperature is 750 degreeC for the numbers 13-5 to 13-7, the coverage judgment was "x (defect)".

  Moreover, from the result shown in Table 3, since the number 0-5 to the number 0-7 did not provide the first holding temperature, the crack determination was “x (defect)”.

  As described above, when a binder or a dispersant is used for forming the internal electrode or the ceramic layer, if the temperature rising rate between 600 ° C. and 900 ° C., which is between the first holding temperature and the second holding temperature, is increased, it remains. Since structural defects due to organic combustion gases may occur, the first holding temperature is held at a predetermined temperature (first holding temperature) between 600 ° C. and 700 ° C., and the first holding temperature and the second holding temperature. It was recognized that it was necessary to degrease until a structural defect was difficult to occur.

  In addition, when a binder or a dispersant is used for forming the internal electrode or the ceramic layer, it cannot be sufficiently degreased only by holding at a predetermined temperature (first holding temperature) between 600 ° C. and 700 ° C., and 900 ° C. Since structural defects may occur due to the rapid combustion gas of the remaining organic matter at higher temperatures, it is held at a predetermined temperature (second holding temperature) between 800 ° C. and 900 ° C., and structural defects at temperatures higher than 900 ° C. It was recognized that it was necessary to degrease until it became difficult to occur.

(Experimental example 2)
In Experimental Example 2, in the method for manufacturing a multilayer ceramic capacitor according to the present invention, when Cu powder is used as the material of the conductive paste, the rate of temperature increase between the first holding temperature and the second holding temperature is changed. An evaluation experiment was conducted on the coverage ratio of the internal electrode and the crack generation rate of the multilayer ceramic capacitor. Therefore, a multilayer ceramic capacitor as a sample was produced as follows.

  First, 35 parts by weight of Cu powder having a specific surface area diameter (BET diameter) of 250 nm, 3 parts by weight of barium titanate powder having a specific surface area diameter (BET diameter) of 20 nm, 5 parts by weight of a polymeric dispersant, ethyl cellulose resin and dihydro The mixture was mixed with 57 parts by weight of an organic vehicle made of terpineol acetate, and a conductive paste was obtained using a pot mill.

  Then, a ceramic material mainly composed of barium titanate having a specific surface area diameter (BET diameter) of 200 nm, an organic binder, an organic solvent, a plasticizer, and a dispersant are mixed at a predetermined ratio, and wet dispersion is performed using a ball mill. Processing gave a ceramic slurry. Next, a ceramic green sheet is obtained by forming this ceramic slurry on a PET (polyethylene terephthalate) film using a doctor blade method so that the thickness of the dried ceramic layer 14 is 2.0 μm. It was.

  Subsequently, on the ceramic green sheet described above, the Cu powder after drying is formed with a pattern in which the planar dimension of the chip-shaped laminate after cutting and firing obtained later is 1.0 mm × 0.5 mm. The conductive paste described above was printed by a screen printer so that the thickness of the used internal electrodes 16a and 16b was 0.5 μm, and a conductive coating film to be an internal electrode was formed.

  And after peeling the ceramic green sheet on which the conductive coating film was printed from the PET film, 200 ceramic green sheets were stacked, put into a predetermined mold, and pressed.

  Subsequently, the pressed multilayer body block was cut into a predetermined size, and a capacitor body as a chip-shaped unfired ceramic body to be an individual multilayer ceramic capacitor was obtained.

Then, this unfired capacitor body is degreased in nitrogen at a temperature of 280 ° C. for 10 hours, and then the atmosphere in the firing furnace is changed to N with an oxygen partial pressure of 10 ⁻¹³ MPa to 10 ⁻²⁰ MPa. It was adjusted to ₂ -H ₂ O-H ₂ mixed atmosphere. As a firing profile, first, the temperature was raised from room temperature to 650 ° C. at a rate of 3.3 ° C./min, and held at a predetermined temperature ± 5 ° C. (first holding temperature) between the reached 650 ° C. for 2 hours. Next, the temperature was raised to 800 ° C. at a rate of 1 ° C. to 100 ° C./min, and held at a predetermined temperature ± 5 ° C. (second holding temperature) between the reached 800 ° C. for 2 hours. Next, the temperature is raised to 1210 ° C. (third holding temperature) at a rate of 8 ° C./min in an N ₂ —H ₂ O—H ₂ mixed atmosphere where the oxygen partial pressure is 10 ⁻⁷ MPa to 10 ⁻⁸ MPa. Baked with a profile that was held for 1 hour. And after hold | maintaining at 3rd holding | maintenance temperature, it cooled to normal temperature with the temperature-fall rate of 3.3 degree-C / min. Then, the external electrodes 18a and 18b are formed by applying and baking Cu on both end faces of the ceramic element 12, and number 14-1 to number 14-7 are laminated based on the conditions of each firing profile shown in Table 4. A sample of the ceramic capacitor 10 was prepared.

  Eight multilayer ceramic capacitors 10 are prepared for each sample for evaluation of the internal electrode coverage, and 100 multilayer ceramic capacitors 10 are prepared for each sample for evaluation of the crack rate. It was.

First, 8 multilayer ceramic capacitors prepared for the evaluation of the coverage of the internal electrode are peeled off at the interface between the electrode layer and the dielectric layer, and the average value of 8 of the ratio of the metal portion of the peeled surface is taken as the coverage Calculated. In the coverage judgment, less than 65% was evaluated as “x (defect)”, 65% or more and less than 75% as “◯ (good)”, and 75% or more as “◎ (excellent)”.
In addition, the crack rate of multilayer ceramic capacitors prepared for evaluation of crack rate is determined by the appearance of cracks when structural defects are observed by external observation with an optical microscope and nondestructive internal observation with an ultrasonic microscope. As calculated. In the case of crack determination, the case where no crack occurred was set as “◯ (good)”, and the case where a crack occurred was set as “x (defective)”.
Table 4 shows the evaluation results obtained by the above evaluation experiment.

  From the results shown in Table 4, in No. 14-1 to No. 14-7, the temperature increase rate between the first holding temperature and the second holding temperature is 1 ° C. to 10 ° C. like No. 14-1 to No. 14-4. It can be seen that the coverage ratio was significantly improved under the conditions of the heating rate of 20 ° C./min or higher as in the case of No. 14-5 to No. 14-7 as compared with the condition of ° C./min. Moreover, the tendency for the coverage ratio to further improve as the heating rate increased was observed.

  From the above, even when Cu powder is used as the material of the conductive paste, the rate of temperature increase in the 600 ° C. to 900 ° C. range between the first holding temperature and the second holding temperature is the same as when Ni powder is used. It was confirmed that setting the temperature to 20 ° C./min or more is effective in improving the coverage of the internal electrode of the multilayer ceramic capacitor.

(Experimental example 3)
In Experimental Example 3, when the particle diameter ratio between the specific surface area diameter of the conductive powder and the specific surface area diameter of the ceramic powder used to obtain the conductive paste of the method for manufacturing the multilayer ceramic capacitor according to the present invention is changed. An evaluation experiment was conducted for the coverage ratio of the internal electrode. Therefore, a multilayer ceramic capacitor as a sample was produced as follows.

  First, 35 parts by weight of Ni powder having a specific surface area diameter (BET diameter) of 100 nm to 300 nm, 3 parts by weight of barium titanate powder having a specific surface area diameter (BET diameter) of 4 nm to 100 nm, 5 parts by weight of a polymeric dispersant, The mixture was mixed with 57 parts by weight of an organic vehicle composed of ethyl cellulose resin and dihydroterpineol acetate, and a conductive paste was obtained using a pot mill.

  Then, a ceramic material mainly composed of barium titanate having a specific surface area diameter (BET diameter) of 200 nm, an organic binder, an organic solvent, a plasticizer, and a dispersant are mixed at a predetermined ratio, and wet dispersion is performed using a ball mill. Processing gave a ceramic slurry. Next, a ceramic green sheet is obtained by molding this ceramic slurry on a PET (polyethylene terephthalate) film using a doctor blade method so that the thickness of the ceramic layer 14 after drying is 1.0 μm. It was.

  Subsequently, on the ceramic green sheet described above, the Ni powder after drying has a pattern in which the planar dimension of the chip-shaped laminate after cutting and firing obtained later is 1.0 mm × 0.5 mm. The conductive paste described above was printed by a screen printer so that the thickness of the used internal electrodes 16a and 16b was 0.5 μm, and a conductive coating film to be an internal electrode was formed.

  And after peeling the ceramic green sheet on which the conductive coating film was printed from the PET film, 200 ceramic green sheets were stacked, put into a predetermined mold, and pressed.

  Subsequently, the pressed multilayer body block was cut into a predetermined size, and a capacitor body as a chip-shaped unfired ceramic body to be an individual multilayer ceramic capacitor was obtained.

Then, this unfired capacitor body is degreased in nitrogen at a temperature of 280 ° C. for 10 hours, and then the atmosphere in the firing furnace is changed to N with an oxygen partial pressure of 10 ⁻¹³ MPa to 10 ⁻²⁰ MPa. It was adjusted to ₂ -H ₂ O-H ₂ mixed atmosphere. As a firing profile, the temperature was raised from room temperature at a rate of 3.3 ° C./min, and held for 2 hours at a predetermined temperature ± 5 ° C. between the reached 650 ° C. Next, the temperature was raised to 800 ° C. at a rate of 20 ° C./min, and held at 800 ° C. for 2 hours. Next, in an N ₂ —H ₂ O—H ₂ mixed atmosphere in which the oxygen partial pressure is 10 ⁻⁸ MPa to 10 ⁻⁹ MPa, the temperature is raised to 1210 ° C. at a rate of 8 ° C./min and held for 1 hour. Was fired. And after hold | maintaining at 3rd holding | maintenance temperature, it cooled to normal temperature with the temperature-fall rate of 3.3 degree-C / min. Then, external electrodes 18a and 18b are formed by applying and baking Cu on both end faces of the ceramic element 12 to obtain conductive pastes as shown in Table 5 as numbers 15-1 to 17-4. A multilayer ceramic capacitor 10 was prepared based on various conditions in which the particle size ratio between the specific surface area diameter of the conductive powder and the specific surface area diameter of the ceramic powder was changed.

  For evaluating the coverage of the internal electrodes, eight multilayer ceramic capacitors 10 were prepared for each sample.

Eight prepared multilayer ceramic capacitors were peeled off at the interface between the electrode layer and the dielectric layer, and the average value of eight of the ratio of the metal portion of the peeled surface was calculated as coverage. In the coverage judgment, less than 65% was evaluated as “x (defect)”, 65% or more and less than 75% as “◯ (good)”, and 75% or more as “◎ (excellent)”.
Table 5 shows the evaluation results obtained by the above evaluation experiment.

  From the results shown in Table 5, in the numbers 15-1 to 17-4, the ratio of the specific surface area of the conductive powder and the specific surface area of the ceramic powder is (particle ratio of ceramic powder specific surface area) / (conductive). When the specific powder surface area diameter is in the range of 0.01 to 0.20, it was confirmed that the coverage ratio of the internal electrode was 65% or more in any sample.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is carried out within the range of the summary.

  That is, in the above-described embodiment, the manufacturing method of the multilayer ceramic capacitor has been described as an example. However, in addition to the multilayer ceramic capacitor, the present invention includes various multilayer ceramics such as a multilayer ceramic varistor, a multilayer ceramic inductor, and a multilayer ceramic thermistor. It is possible to apply to the manufacturing method of an electronic component.

  In the above-described embodiment, for example, a plurality of internal electrodes are used. However, in a multilayer ceramic capacitor, a multilayer ceramic varistor, and a multilayer ceramic thermistor, two or more internal electrodes may be used. In the multilayer ceramic inductor, one or more internal electrodes may be used.

DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 12 Ceramic element 14 Ceramic layer 16a, 16b Internal electrode 18a, 18b External electrode

Claims (7)

In a method for producing a multilayer ceramic electronic component including a step of firing an unfired ceramic body and having an internal electrode made of a material consisting of at least conductive powder and oxide powder,
After holding at least one temperature between 600 ° C. and 700 ° C. in the firing step, the temperature is raised at a rate of 20 ° C./min or more in a temperature range of at least 100 ° C. between 600 ° C. and 900 ° C. And a method for producing a multilayer ceramic electronic component, wherein the multilayer ceramic electronic component is further held at a temperature between 800 ° C. and 900 ° C. at least one temperature.   The conductive powder constituting the internal electrode includes at least one selected from the group consisting of Ni and Cu, or an alloy containing at least one selected from the group of substances. The manufacturing method of the multilayer ceramic electronic component of description.   The oxide constituting the internal electrode is at least one or more metal oxides or composite metal oxides composed of an element lower than the main component element of the conductive powder. The manufacturing method of the multilayer ceramic electronic component of 2.   (Ceramic powder specific surface area diameter) / (conductive powder specific surface area diameter), which is the particle size ratio of the specific surface area diameter of the conductive powder constituting the internal electrode and the specific surface area diameter of the ceramic powder, is 0.01 or more. The method for producing a multilayer ceramic electronic component according to any one of claims 1 to 3, wherein the value is 0.20 or less.   5. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the oxide powder constituting the internal electrode is the same component as a main component of the ceramic layer.   6. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the oxide powder constituting the internal electrode is an oxide having a perovskite structure.   The method for producing a multilayer ceramic electronic component according to any one of claims 1 to 6, wherein a main component of the oxide powder constituting the internal electrode is barium titanate.

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