JP2015131982A - Composite powder and production method of the same, as well as conductive paste using the same, and laminated ceramic electronic component using the conductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide composite powder which is used for obtaining a conductive paste for forming an internal electrode of a laminated ceramic electronic component, and with which an excellent suppression effect of sintering and excellent continuity of electrodes are obtained in forming an electrode pattern by using the conductive paste and baking, and to provide a production method of the composite powder.SOLUTION: Composite powder includes: metal powder having protrusions, and out of the protrusion, salients are being a hydroxide or an oxide; and an inorganic compound covering at least a portion of the surface of the metal powder. For forming the composite powder, the metal powder is synthesized by a liquid phase synthesis method, subsequently the metal powder obtained by the liquid phase synthesis method is dispersed in the inorganic compound and a solvent, and subsequently the metal powder dispersed in the inorganic compound and the solvent is dried and jet-pulverized.

Description

  The present invention relates to a composite powder, a method for producing the same, a conductive paste using the same, and a multilayer ceramic electronic component using the same, and more particularly, for example, a composite powder used for forming an internal electrode of a multilayer ceramic electronic component and its The present invention relates to a manufacturing method, a conductive paste using the same, and a multilayer ceramic electronic component using the same.

  FIG. 1 is a cross-sectional view showing a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component. The multilayer ceramic capacitor 10 includes, for example, a rectangular parallelepiped base 12. The substrate 12 is formed as a laminate in which the dielectric ceramic layers 14 and the internal electrode layers 16 are alternately arranged. The surfaces of the plurality of internal electrode layers 16 are arranged so as to face each other at the central portion of the base 12, and the adjacent internal electrode layers 16 are drawn out to the opposing end faces of the base 12. External electrodes 18 are formed on the opposing end surfaces of the substrate 12, and the internal electrodes 16 drawn out to the external electrodes 18 are electrically connected. A Ni plating layer or a Sn plating layer is formed on the external electrode 18 as necessary. As described above, the internal electrodes 16 facing each other are alternately connected to the external electrodes 18 formed on both end surfaces of the base 12, and a capacitance is formed between the two external electrodes 18.

  When producing such a multilayer ceramic capacitor 10, a ceramic green sheet formed of a dielectric ceramic material is prepared. An internal electrode pattern is formed on the ceramic green sheet with a conductive paste containing metal powder. A plurality of ceramic green sheets on which internal electrode patterns are formed are stacked, and if necessary, ceramic green sheets on which no internal electrode patterns are formed are stacked on both sides thereof. The laminated ceramic green sheets are pressed and cut so that adjacent internal electrode patterns are alternately exposed at both ends. The multilayer chip thus obtained is fired to form the base 12 including the dielectric ceramic layer 14 and the internal electrode layer 16. Then, an external electrode 18 is formed by applying and baking a conductive paste on both end faces of the substrate 12. The external electrode 18 is formed with the above-described plating layer as necessary, and the multilayer ceramic capacitor 10 is obtained.

  In order to increase the capacity and size of the multilayer ceramic capacitor 10 and the like, it is important to reduce the thickness of the internal electrode layer 16. However, when the internal electrode layer 16 is thinned, during sintering, the metal component contained in the conductive paste forming the internal electrode layer 16 and a ceramic green sheet having a sintering temperature of generally 1000 ° C. or more are used. There is a difference in shrinkage behavior. Therefore, the problem of electrode breakage occurs in the internal electrode layer 16 of the obtained multilayer ceramic capacitor 10. In other words, in the sintering process, the metal component begins to sinter first than the ceramic green sheet, and the metal component grows excessively before reaching the temperature at which the ceramic starts to sinter. There is. When the electrode continuity is lowered, the capacitance of the multilayer ceramic capacitor is lowered.

  In order to form an internal electrode that can reliably prevent such structural defects and capacitance reduction of multilayer ceramic electronic components, nickel powder is the main component, the same composition as the dielectric layer, and the average It is disclosed that 5-30% by weight of a co-material having a maximum particle size of 0.1 μm is added to form a conductor paste. A multilayer ceramic electronic component is manufactured by alternately stacking internal electrodes and dielectric layers using this conductive paste (see Patent Document 1).

Also, the aim of sintering inhibiting effect of the Ni powder, selected from among _{TiO 2, MnO 2, Cr 2} O 3, Al 2 O 3, SiO 2, Y 2 O 3, ZrO 2, BaTiO 3 on the Ni powder surface It is disclosed to produce a composite Ni powder in which at least one oxide is present. In this case, a method is adopted in which Ni and the oxide are added to water by a liquid phase method, and a composite Ni powder containing the oxide is obtained by heating and pH adjustment (see Patent Document 2).

  In addition, a method for producing a composite copper powder having an average particle size of 10 to 100 nm and having at least one refractory metal selected from tungsten, molybdenum, and tantalum on the surface of copper fine particles, the copper or copper compound and the high A method for producing a composite copper fine powder, characterized in that a compound of a melting point metal is vaporized by thermal plasma and the resulting metal vapor is condensed. By coating these refractory metals on the surface of copper, the aim is to suppress the sintering of copper (see Patent Document 3).

JP 2001-110233 A Japanese Patent Laid-Open No. 11-343501 JP 2007-211132 A

  However, in the conductive paste containing the nickel powder and the co-material of the same composition as the dielectric layer as in Patent Document 1, when the co-material is not uniformly arranged around the metal component, the location where the co-material does not exist Therefore, the sintering of the metal component proceeds. Therefore, there is a problem that a sufficient sintering suppression effect cannot be obtained and electrode continuity is lowered.

  Further, in the case of the composite Ni powder as in Patent Document 2, it is very difficult to form a uniform oxide layer on the surface of the metal powder, and the sintering of the metal component proceeds from the place where the oxide layer is peeled off. There is a problem that a sufficient sintering suppressing effect cannot be obtained.

  Moreover, as shown in Patent Document 3, there is a method of coating the surface of the metal component with a refractory metal, but there is a problem that many refractory metals are expensive and unsuitable for mass production.

Therefore, the main object of the present invention is to obtain a conductive paste for producing an internal electrode of a multilayer ceramic electronic component, and to have a good sintering suppression effect and a good electrode continuity when firing the conductive paste. It is providing the composite powder which can obtain, and its manufacturing method.
Another object of the present invention is to provide a conductive paste having a sintering suppressing effect by using such a composite powder, and to provide a multilayer ceramic electronic component in which no electrode breakage occurs. is there.

The present invention is a composite powder including a metal powder having irregularities on the surface, the convex portion being a hydroxide or an oxide, and an inorganic compound covering at least a part of the surface of the metal powder.
By disposing the inorganic compound around the metal powder, excessive grain growth is suppressed and electrode connectivity is improved in the sintering process of the electrode pattern using the conductive paste using the composite powder. Here, there are irregularities on the surface of the metal powder, and the inorganic compound is uniformly fixed around the metal powder by mixing the metal powder and the inorganic compound whose convex portions are hydroxides or oxides. Moreover, when two or more components are added as an inorganic compound, these may react on the metal powder surface and a coating layer may be formed, and a sintering inhibitory effect may become high.

In such a composite powder, the average value of the aspect ratio (height / width) of the convex portions of the metal powder is preferably 0.20 or more.
By mixing a metal powder having an aspect ratio of 0.20 or more on the surface with an inorganic compound, the inorganic compound adheres uniformly to the surface of the metal powder, and a conductive paste using this composite powder is used. As a result, electrode connectivity is improved.

Moreover, in the composite powder composed of the metal powder coated with the inorganic compound, it is preferable that the average value of the aspect ratio (height / width) of the convex portion of the metal powder after JET grinding is 0.20 or more.
When JET grinding is performed to suppress aggregation and aggregation of metal powder, the aspect ratio of the convex part on the surface of the metal powder is 0.20 or more so that the inorganic compound is uniformly attached to the surface of the metal powder. Can do.

The inorganic compound preferably contains at least one selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Mn, Cr, Al, Si, Y, and Zr salts.
When such an inorganic compound adheres to the surface of the metal powder, excessive grain growth is suppressed during the sintering process of the electrode pattern using the conductive paste, and good electrode continuity can be obtained.

Moreover, it is preferable that the addition amount of an inorganic compound is 0.5-30 mass% with respect to metal powder.
When the added amount of the inorganic compound is less than 0.5% by mass, the entire surface of the metal powder cannot be coated with the inorganic compound, and the sintering proceeds from the metal surface to which the inorganic compound is not attached, and heat shrinkage occurs. It occurs remarkably. When the addition amount of the inorganic compound is larger than 30% by mass, the addition amount of the inorganic compound is excessively large, so that the contact between the metal powders is small, the progress of the sintering is deteriorated, and the electrode continuity is lowered.

The average primary particle size of the metal powder is preferably 50 nm to 1000 nm.
When the average primary particle size of the metal powder is smaller than 50 nm, the contact area between the metal powders is large, and sintering of the conductive paste proceeds. When the average primary particle size of the metal powder is larger than 1000 nm, the contact area between the metal powders is small, the sintering of the conductive paste does not proceed, and the electrode continuity is lowered.

Moreover, it is preferable that the specific surface area of an inorganic compound is 5-500 m < ² > / g.
When the specific surface area of the inorganic compound is larger than 500 m ² / g, the inorganic compound re-aggregates after dispersion and is not uniformly arranged around the metal powder. When the specific surface area of the inorganic compound is smaller than 5 m ² / g, the effect of suppressing the sintering of the conductive paste is small.

In addition, the metal component and the metal powder preferably include at least one of Cu and Ni or an alloy thereof.
Such metal powder functions as a conductive component of the multilayer ceramic electronic component.

The present invention also includes a step of synthesizing a metal powder by a liquid phase synthesis method, a step of dispersing the metal powder obtained by the liquid phase synthesis method in an inorganic compound and a solvent, and a step of dispersing the metal powder in the inorganic compound and the solvent. A method for producing a composite powder, comprising: drying the obtained metal powder and subjecting the powder to JET grinding.
By producing the metal powder by the liquid phase synthesis method, a convex portion having an aspect ratio of 0.20 or more can be formed on the surface of the metal powder. Thus, by forming unevenness on the surface of the metal powder, aggregation of the metal powder is suppressed, and the metal powder and the inorganic compound can be mixed in a highly dispersed state, and the metal powder can be uniformly mixed around the metal powder. An inorganic compound can be fixed. In addition, in this invention, after the liquid phase synthesis of the metal powder, the metal powder and the inorganic compound are dispersed in a solvent, and after drying, JET grinding can be performed to reduce dry aggregation and excellent dispersibility. Composite powder can be obtained.

Moreover, this invention is a conductive paste characterized by using any of the composite powders described above.
By using such a conductive paste, it is possible to form a multilayer ceramic electronic component having an internal electrode layer with good sintering suppression effect and good electrode continuity.

In addition, the present invention is a multilayer ceramic electronic component in which an electrode is formed using the above-described conductive paste.
The multilayer ceramic electronic component of the present invention has a good sintering suppression effect of the internal electrode layer at the time of production, has good electrode continuity, and can obtain predetermined characteristics.

  According to this invention, it is possible to obtain a composite powder for producing a conductive paste that can obtain an electrode layer having a good sintering suppression effect during firing and good electrode continuity. Then, by producing a conductive paste using this composite powder and forming an internal electrode layer using this conductive paste, a multilayer ceramic electronic component having predetermined characteristics can be obtained.

  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.

It is a cross-sectional solution figure which shows an example of the multilayer ceramic capacitor which formed the internal electrode layer with the electrically conductive paste produced using the composite powder. It is a flowchart for producing the composite powder of this invention. It is an illustration figure which shows an example of the spray-drying apparatus used when producing composite powder. It is an illustration figure which shows a mode that an inorganic compound adheres to the surface of metal powder by drying.

  The composite powder of the present invention includes a metal powder having irregularities on the surface. The convex part on the surface of the metal powder is a hydroxide or an oxide, and the aspect ratio (height / width) of the convex part is preferably 0.20 or more. The metal powder is formed of, for example, at least one of Cu and Ni or an alloy thereof. The surface of the metal powder is coated with an inorganic compound. Examples of the inorganic compound used here include at least one selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Mn, Cr, Al, Si, Y, and Zr. In particular, when the composite powder is used to produce a conductive paste for forming an internal electrode of a multilayer ceramic electronic component, it is preferable that the same material as the ceramic material used for the multilayer ceramic electronic component is used as the inorganic compound.

  When an inorganic compound is arranged around the metal powder, excessive grain growth is suppressed during the sintering process of the conductive paste using the composite powder, and an electrode layer is formed using the conductive paste. Electrode connectivity is improved. Here, about the metal powder which has an unevenness | corrugation on the surface and the convex part is a hydroxide or an oxide, aggregation with metal powder is suppressed by mixing with an inorganic compound. Thus, by mixing the metal powder and the inorganic compound in a highly dispersed state, the inorganic compound is uniformly fixed around the metal powder. When the inorganic compound adheres to the surface of the metal powder, excessive grain growth is suppressed during the sintering process of the conductive paste, and good electrode continuity can be obtained.

  Moreover, about the metal powder whose aspect ratio of the convex part of a surface is 0.20 or more, an inorganic compound adheres uniformly to the surface of a metal powder by mixing with an inorganic compound, and the electrically conductive paste using this composite powder By using, electrode connectivity is improved. In addition, even when JET grinding is performed to suppress the aggregation and aggregation of the metal powder, the inorganic compound is uniformly distributed on the surface of the metal powder because the aspect ratio of the convex portion on the surface of the metal powder is 0.20 or more. Can be attached to.

  It is preferable that the addition amount of an inorganic compound is 0.5-30 mass% with respect to metal powder. When the added amount of the inorganic compound is less than 0.5% by mass, the entire surface of the metal powder cannot be covered with the inorganic compound, and the sintering proceeds from the metal surface to which the inorganic compound is not attached, and the heat shrink is remarkable. Occurs. When the addition amount of the inorganic compound is larger than 30% by mass, the addition amount of the inorganic compound is excessively large, so that the contact between the metal powders is small, the progress of the sintering is deteriorated, and the electrode continuity is lowered.

  The average primary particle size of the metal powder is preferably 50 nm to 1000 nm. When the average primary particle size of the metal powder is smaller than 50 nm, the contact area between the metal powders is large, and sintering of the conductive paste proceeds. When the average primary particle size of the metal powder is larger than 1000 nm, the contact area between the metal powders is small, the sintering of the conductive paste does not proceed, and the electrode continuity is lowered.

Further, the specific surface area of the inorganic compound is preferably 5 to 500 m ² / g. When the specific surface area of the inorganic compound is larger than 500 m ² / g, the inorganic compound re-aggregates after dispersion and is not uniformly arranged around the metal powder. When the specific surface area of the inorganic compound is smaller than 5 m ² / g, the effect of suppressing the sintering of the conductive paste is small.

  If a conductive paste is produced using such a composite powder, a multilayer ceramic electronic component having an internal electrode layer with good sintering suppression effect and good electrode continuity can be obtained. Therefore, a multilayer ceramic electronic component having predetermined characteristics can be obtained.

  Below, an example of the manufacturing method of the composite powder used for internal electrode formation of a multilayer ceramic electronic component is demonstrated. Ni is used as the metal powder used here. First, as shown in step S1 of FIG. 2, 45 g of nickel chloride hexahydrate is dissolved in 150 ml of pure water and adjusted so that pH = 2, and a metal salt solution (Ni source) is prepared. The Further, as shown in step S2, a reducing agent solution in which 90 g of hydracin hydrate (reducing agent) and 22.5 g of sodium hydroxide are mixed is prepared.

  The liquid temperature of both the reducing agent solution and the metal salt solution was adjusted to 80 ° C. The metal salt solution was added at 100 ml / min while rotating the reducing agent solution at 200 rpm, and the liquid phase reaction (step S3) Ni powder is produced by a reduction reaction. At this time, nickel and water react to produce nickel hydroxide, and irregularities are formed on the surface of the nickel hydroxide. The average value of the aspect ratio (height / width) of the convex portions is 0.20 or more. Thereafter, as shown in step S4, the obtained powder is washed with pure water. This is one of the finished products of metal powder. Incidentally, the Ni powder that has been subjected to JET pulverization thereafter has a smooth surface due to the collision between the particles, and the aspect ratio of the convex portion is less than 0.00 to 0.20. This is also one of the finished products of metal powder. The pure powder washed Ni powder is adjusted in step S5 in order to proceed to the next step.

  As described above, the aspect ratio was calculated for the obtained Ni powder both when JET grinding was performed and when it was not performed. In this case, first, measurement is performed with a SEM at a magnification of 100,000 times. As for the measurement location, four surface protrusions were measured for four particles. The aspect ratio was calculated by measuring the width and height of the convex portion and taking the height / width as the aspect ratio. Here, the width and height of the protrusions were measured before JET grinding for those not subjected to JET grinding, and after JET grinding for those subjected to JET grinding.

In addition, as shown in step S6, a fine inorganic compound is prepared. Here, when the finally obtained composite powder is used as a material for a conductive paste for forming an internal electrode layer of a multilayer ceramic electronic component, the inorganic compound is the same as the ceramic material of the multilayer ceramic electronic component. It is preferable to be used. For example, when used as a material of a conductive paste for producing a multilayer ceramic capacitor as shown in FIG. 1, a dielectric material such as BaTiO ₃ is used as the inorganic compound. This fine inorganic compound is dispersed as shown in step S7. As shown in step S8, a predetermined amount of the inorganic compound dispersed in the solution of the metal powder before JET pulverization and pure water is added to the inorganic compound and dispersed in a ball mill or the like as shown in step S8. Is obtained. At this time, an organic solvent may be used instead of pure water. Moreover, you may use additives, such as a dispersing agent, as needed.

  In step S9, the obtained turbid liquid is spray-dried by a spray-drying device such as a spray pyrolysis device (RH-2 manufactured by Okawara Chemical Co., Ltd.). As shown in FIG. 3, the spray drying is performed at an inlet temperature of 250 ° C. while flowing 50 L / min of air or gas to obtain a composite powder. In the spray pyrolysis apparatus of FIG. 3, the slurry containing the inorganic compound and the metal component is heated while being sprayed in a spray form at an inlet temperature of 250 ° C. In the present invention, all such drying methods are called spray drying. By performing spray drying, as shown in FIG. 4, a composite powder in which the inorganic compound attached to the surface of the metal powder is fixed is formed. At this time, since the irregularities are formed on the surface of the metal powder, the inorganic compound is fixed to the entire surface of the metal powder. The spray-dried composite powder is sent to the bag filter at an outlet temperature of 110 ° C., and air or gas passes through the bag filter to recover the composite powder.

  In some cases, inorganic compounds react with each other in the process of spray drying, and the surface of the metal powder is coated with the reacted inorganic compound. The state of the dried metal powder coated with these inorganic compounds is the finished product of the composite powder. However, in order to suppress aggregation and coagulation of the composite powder, as shown in step S10, JET pulverized one is also one of the finished products. At this time, when the surface of the metal powder is completely covered with the inorganic compound, the aspect ratio of the convex part of the metal powder is 0.20 or more, and the aspect ratio of the convex part of the uncoated part is 0.00. It will be less than 0.20.

  The composite powder has irregularities on the surface of the metal powder, the convex portion is a metal hydroxide or a metal oxide, and at least a part of the surface of the metal powder is coated with an inorganic compound. The aspect ratio (height / width) of the convex portion of the metal powder is 0.20 or more in the metal powder after the liquid phase reaction and before the JET grinding. When JET grinding is performed, the aspect ratio of the portion coated with the inorganic compound is 0.20 or more, and the aspect ratio of the uncoated portion is 0.00 to less than 0.20.

  The composite powder of this invention is used for producing a conductive paste. In this case, a predetermined amount of the obtained composite powder and organic solvent are weighed and stirred to produce a first mill base. Here, if necessary, an arbitrary amount of a dispersant or additive may be kneaded. Next, the first mill base is kneaded by a dispersion method such as a three-roll mill, and the metal powder is uniformly dispersed to obtain a second mill base. Further, a predetermined amount of the binder resin and the organic solvent are weighed and stirred in the second mill base to obtain a conductive paste. At this time, an arbitrary amount of additives may be kneaded as necessary. Moreover, the organic solvent different from a 1st mill base may be mixed as needed.

  A multilayer ceramic electronic component can be produced using the conductive paste thus obtained. In this case, as described for the method of manufacturing the multilayer ceramic capacitor 10 shown in FIG. 1, the internal electrode pattern is formed on the ceramic green sheet using the conductive paste, and the ceramic green sheet on which the internal electrode pattern is formed and the internal A ceramic green sheet on which no electrode pattern is formed is laminated and pressure-bonded. The laminated body thus obtained is cut to form a laminated body chip, and this laminated body chip is baked to form a substrate including an internal electrode layer and a dielectric layer. An external electrode is formed on the substrate, and the internal electrode and the external electrode are electrically connected to form a multilayer ceramic electronic component.

Next, a method for evaluating the thermal shrinkage rate of the obtained composite powder will be described. First, an arbitrary amount of powder is collected from the obtained composite powder and compressed at a pressure of 6 kg / m ² to produce a cylindrical pellet having a diameter of about 4 mm and a height of about 2 mm. Using the pellets, the thermal contraction rate was measured at a heating rate of 10 ° C./min in an N ₂ gas atmosphere using a thermomechanical analyzer (TMA8310 manufactured by Rigaku Corporation).

  The thermal shrinkage rate is an index of a phenomenon in which the metal powder and the composite powder are sintered and contracted, and indicates that the larger the thermal contraction, the more the sintering proceeds. Judgment is made by comparing the heat shrinkage rates at 600 ° C. and 800 ° C. When the shrinkage rates at 600 ° C. and 800 ° C. are 3% or more, “x” marks, and when the shrinkage rate at 600 ° C. is 3% or less, 800 ° C. shrinkage When the rate was 3% or more, it was marked with “◯”, and when the shrinkage at 600 ° C. and 800 ° C. was 3% or less, it was marked with “◎”. The “」 ”and“ ◯ ”marks indicate that the quality is good, and the“ × ”marks indicate that the quality cannot be used as the internal electrode material.

Moreover, a conductive paste is produced using the obtained composite powder, and the conductive paste is printed on a dielectric green sheet having a thickness of 3 μm so as to have a coating thickness of 1 μm, thereby forming a printed film. The dielectric green sheet on which the printed film is formed is heated at a temperature rising rate of 10 ° C./min and fired at 1100 ° C. for 2 hours in an N ₂ atmosphere. Then, using a metal microscope, transmitted light is irradiated from the back surface of the sheet, and the formed conductor film surface is observed in 10 fields under the condition of 100 times magnification. The average of the area covered with the conductor film in these entire observation images was calculated as “coverage” and used as an index of electrode continuity. In the determination, a mark “印” is given when the coverage is 70% or more, a mark “◯” is given when the coverage is 50% or more and less than 70%, and a mark “X” is given when the coverage is lower than 50%. The “◎” mark indicates that the quality is good and can be used. The “○” mark is slightly poor in quality, but can be used. The “x” mark indicates that the quality cannot be used as an electrode layer.

  In the heat shrinkage evaluation and the electrode continuity evaluation, if even one “x” mark is given, the overall judgment is “x” mark, and there is no “x” mark but only “○” mark and “◎” mark. Is marked with “◯” in the overall judgment, and when all are marked with “◎”, it is marked with “◎” in the overall judgment.

  First, in the flowchart shown in FIG. 2, for the metal powder that has undergone the pure water cleaning in step S <b> 4, the heat shrinkage rate evaluation, the electrode continuity evaluation, and the overall evaluation are performed by changing the aspect ratio of the convex portion on the surface of the metal powder. went. Here, Examples 1 to 5 in Table 1 show the case without JET grinding, and Comparative Example 1 in Table 2 shows the case with JET grinding.

  As can be seen from Table 1, when the aspect ratio of the surface protrusion is 0.20 to 0.69, the heat shrinkage rate at 600 ° C. and 800 ° C. is 3% or less, and it is confirmed that the sintering suppression effect is high. It was done. Moreover, the electrode coverage was 72.5% or more, and it was confirmed that the electrode continuity was high. On the other hand, when the average aspect ratio was 0.00, as shown in Table 2, the heat shrinkage rate at 600 ° C. and 800 ° C. was larger than 3%, and it was confirmed that the heat shrinkage was significant. Further, the electrode coverage was 49.5%, and it was confirmed that the electrode continuity was extremely lowered.

  Next, in the flowchart shown in FIG. 2, for the composite powder after spray drying in step S <b> 9, the heat shrinkage rate evaluation, the electrode continuity evaluation, and the overall evaluation were performed by changing the aspect ratio of the convex portion of the composite powder surface. . Here, Examples 6 to 8 in Table 3 show cases without JET grinding, and Comparative Examples 2 to 4 in Table 4 show cases with JET grinding.

  As can be seen from Table 3, when the surface protrusion has an aspect ratio of 0.20 or more, the heat shrinkage at 600 ° C. and 800 ° C. was 3% or less, and it was confirmed that the sintering suppression effect was high. In addition, the electrode coverage was 73.1% or higher, and it was confirmed that the electrode continuity was high. On the other hand, when the average aspect ratio is 0.01 to 0.19, as shown in Table 4, the heat shrinkage rate at 600 ° C. is 3% or less, and the sintering suppressing effect is high. The inhibitory effect decreased. Moreover, the electrode coverage was 50.5% to 71.5%, and it was confirmed that the electrode continuity was slightly lowered.

  As the inorganic compound prepared in step S6 shown in FIG. 2, at least one was selected from a set of Mg, Ca, Sr, Ba, Ti, Mn, Cr, Al, Si, Y, and Zr salts. And thermal contraction rate evaluation, electrode continuity evaluation, and comprehensive evaluation were performed, and the results are shown in Examples 9 to 17 in Table 5.

  As can be seen from Table 5, in the inorganic compound used in this example, the heat shrinkage rate at 600 ° C. and 800 ° C. is both 3% or less, and the sintering suppression effect is high, and the electrode coverage is 80% or more. It was confirmed that high electrode continuity was obtained.

  About Examples 18-20 whose addition amount of the inorganic compound described in Example 3 is 0.5-30 mass% with respect to a metal component, and Comparative Examples 5 and 6 which are 0.2-50 mass%, Thermal shrinkage rate evaluation, electrode continuity evaluation and comprehensive evaluation were performed. The results are shown in Tables 6 and 7.

  As can be seen from Table 6, when the addition amount of the inorganic compound is 0.5 to 30% by mass with respect to the metal component, the heat shrinkage rate at 600 ° C. and 800 ° C. is 3% or less, and the sintering suppressing effect is high The electrode coverage was 80% or more, and high electrode continuity was obtained. On the other hand, as can be seen from Table 7, when the addition amount of the inorganic compound is 0.2% by mass and 50% by mass with respect to the metal component, the heat shrinkage rate at 600 ° C. is 3% or less, and the sintering suppressing effect is Although high, at 800 ° C., the sintering suppressing effect was slightly reduced. The electrode coverage was 69.5-70.1%.

  The average primary particle size of the metal powder obtained in step S4 of FIG. 2 was changed in the range of 30 to 1500 nm, and thermal shrinkage evaluation, electrode continuity evaluation, and comprehensive evaluation were performed. The average primary particle size here is obtained by acquiring an image at an arbitrary magnification using a scanning electron microscope, measuring the diameter by randomly selecting n = 200 powders for each observation image, and n = The average value of 200 powder diameters was calculated and used as the average primary particle size. And thermal contraction rate evaluation, electrode continuity evaluation, and comprehensive evaluation were performed, and the results are shown in Table 8 and Table 9.

  As can be seen from Table 8, when the average primary particle size of the metal powder is 50 to 1000 nm, the heat shrinkage rate at 600 ° C. and 800 ° C. is 3% or less, and it is confirmed that a high sintering suppression effect is obtained. On the other hand, as can be seen from Table 9, when the average primary particle size of the metal powder was 30 nm and 1500 nm, the thermal shrinkage rates at 600 ° C. were as good as 1.4% and 1.6%, respectively. The thermal shrinkage ratios in each were 4.2%, 4.7%, and 3% or more, respectively, confirming that the sintering suppression effect was slightly low. The electrode coverage was 71.2% and 68.5%, respectively.

Next, the specific surface area of the inorganic compound for obtaining the blended powder is changed in the range of ³ to 600 m ² / g, and the thermal shrinkage rate evaluation, the electrode continuity evaluation and the comprehensive evaluation are performed. The results are shown in Table 10 and Table 11. It was shown to. Here, the specific surface area is a value obtained by measuring the specific surface area based on the amount of N ₂ adsorbed on the particle surface by a specific surface area measuring device (Max Soap).

As can be seen from Table 10, when the specific surface area of the inorganic compound is 5 to 500 m ² / g, the heat shrinkage rate at 600 ° C. and 800 ° C. is 3% or less, and it is confirmed that a high sintering suppression effect is obtained. It was. Moreover, the electrode coverage was 77.5% or more, and it was confirmed that the electrode continuity was high. On the other hand, as can be seen from Table 11, when the specific surface area of the inorganic compound was 3 m ² / g and 600 m ² / g, the thermal shrinkage rates at 600 ° C. were as good as 1.7% and 1.4%, respectively. The thermal shrinkage at 800 ° C. was 4.7%, 4.9% and 3% or more, respectively, and it was confirmed that the sintering suppression effect was slightly low. Moreover, the electrode coverage was 68.4% and 65.4%, respectively.

  Further, Cu was used as a metal component, and thermal shrinkage evaluation, electrode continuity evaluation and comprehensive evaluation were performed. The results are shown in Table 12.

  As can be seen from Table 12, in this case, the thermal shrinkage at 600 ° C. and 800 ° C. was 3% or less, and it was confirmed that a high sintering suppression effect was obtained. Moreover, the electrode coverage was 71.5% or more, and it was confirmed that the electrode continuity was also high. In addition, as metal powder, it is applicable also to Ag and Pd other than Ni and Cu.

DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 12 Base | substrate 14 Dielectric ceramic layer 16 Internal electrode layer 18 External electrode

Claims (11)

A composite powder comprising a metal powder having irregularities on the surface, the convex part being a hydroxide or an oxide, and an inorganic compound covering at least a part of the surface of the metal powder.   The composite powder according to claim 1, wherein an average value of aspect ratios (height / width) of the convex portions of the metal powder is 0.20 or more.   The average value of the aspect ratio (height / width) of the convex portions of the metal powder after the metal powder coated with the inorganic compound is subjected to JET grinding is 0.20 or more. 2. The composite powder according to 2.   The inorganic compound includes at least one selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Mn, Cr, Al, Si, Y, and Zr salts. Item 4. The composite powder according to any one of Items 3.   5. The composite powder according to claim 1, wherein an addition amount of the inorganic compound is 0.5 to 30% by mass with respect to the metal powder.   6. The composite powder according to claim 1, wherein the average primary particle size of the metal powder is 50 nm to 1000 nm. 7. The composite powder according to claim 1, wherein the inorganic compound has a specific surface area of 5 to 500 m ² / g.   The composite powder according to claim 1, wherein the metal powder includes at least one of Cu and Ni or an alloy thereof. A step of synthesizing a metal powder by a liquid phase synthesis method,
A step of dispersing the metal powder obtained by the liquid phase synthesis method in an inorganic compound and a solvent, and a step of drying the metal powder dispersed in the inorganic compound and the solvent and pulverizing them by JET. The manufacturing method of composite powder.   A conductive paste using the composite powder according to any one of claims 1 to 8.   A multilayer ceramic electronic component, wherein an electrode is formed using the conductive paste according to claim 10.