INTERNAL ELECTRODE COMPOSITION OF MUTI LAYER CERAMIC CAPACITOR FOR VEHICLES

Abstract

Provided is an internal electrode composition of a multi-layer ceramic capacitor for a vehicle, which includes metal powder and a ceramic base substance, wherein the metal powder includes Ni of 79 to 91.9% by weight (wt %), and Sn of 0.1 to 2.0 wt %, and the ceramic base substance includes BaTiO.sub.3 of 7.5 to 15 wt %, and MgCO.sub.3 of 0.5 to 4.0 wt %, and a specific surface area of MgCO.sub.3 is greater than a specific surface area of BaTiO.sub.3.

Claims

1. An internal electrode composition of a multi-layer ceramic capacitor for a vehicle comprising: metal powder including Ni and Sn; and a ceramic base substance including BaTiO.sub.3 and MgCO.sub.3, wherein Ni of 79 to 91.9% by weight (wt %), Sn of 0.1 to 2.0 wt %, BaTiO.sub.3 of 7.5 to 15 wt %, and MgCO.sub.3 of 0.5 to 4.0 wt %, are mixed, and a specific surface area of MgCO.sub.3 is greater than a specific surface area of BaTiO.sub.3.

2. The internal electrode composition of claim 1, wherein the specific surface area of MgCO.sub.3 is 1.4 to 5.0 times as large as the specific surface area of BaTiO.sub.3.

3. The internal electrode composition of claim 1, wherein the specific surface area of BaTiO.sub.3 is 20 to 60 m.sup.2/g.

4. The internal electrode composition of claim 1, wherein the specific surface area of MgCO.sub.3 is 35 to 100 m.sup.2/g.

5. The internal electrode composition of claim 1, wherein MgCO.sub.3 has a flake-like structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a flowchart of a process of manufacturing a paste for an internal electrode using an internal electrode composition of a multi-layer ceramic capacitor for a vehicle according to the present disclosure.

[0015] FIG. 2 is a cross-sectional view of a multi-layer ceramic capacitor manufactured using the paste for an internal electrode illustrated in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an internal electrode composition of a multi-layer ceramic capacitor for a vehicle according to an embodiment of the present disclosure is described with reference to the accompanying drawings.

[0017] As shown in FIG. 1, an internal electrode composition of the multi-layer ceramic capacitor for a vehicle according to an embodiment of the present disclosure includes metal powder and a ceramic base substance. The metal powder includes Ni and Sn, and the ceramic base substance includes BaTiO.sub.3 and MgCO.sub.3.

[0018] The internal electrode composition of the multi-layer ceramic capacitor for a vehicle according to an embodiment of the present disclosure is specifically formed by mixing Ni of 79 to 91.9 wt %, Sn of 0.1 to 2.0 wt %, BaTiO.sub.3 of 7.5 to 15 wt %, and MgCO.sub.3 of 0.5 to 4.0 wt %.

[0019] A specific surface area (by BET) of MgCO.sub.3 is greater than a specific surface area (by BET) of BaTiO.sub.3, and in particular, the specific surface area of MgCO.sub.3 is 1.4 to 5.0 times as large as the specific surface area of BaTiO.sub.3, BaTiO.sub.3 of the ceramic base substance has the specific surface area of 20 to 60 m.sup.2/g, MgCO.sub.3 has the specific surface area of 35 to 100 m.sup.2/g, and MgCO.sub.3 has a flake-like structure.

[0020] A method of manufacturing a paste for an internal electrode including an internal electrode composition of a multi-layer ceramic capacitor for a vehicle according to an embodiment of the present disclosure.

[0021] As shown in FIG. 1, in the method of manufacturing a metal paste for an internal electrode of a multi-layer ceramic capacitor according to an embodiment of the present disclosure, first, metal powder is prepared (S100). The metal powder includes Ni and Sn, and is formed by mixing Ni and Sn.

[0022] Next, ceramic base substance powder is prepared (S200).

[0023] The ceramic base substance includes BaTiO.sub.3 and MgCO.sub.3, and a specific surface area of MgCO.sub.3 is greater than that of BaTiO.sub.3. For example, the specific surface area of MgCO.sub.3 is 1.4 to 5.0 times as large as the specific surface area of BaTiO.sub.3, BaTiO.sub.3 of the ceramic base substance has the specific surface area of 20 to 60 m.sup.2/g, MgCO.sub.3 has the specific surface area of 35 to 100 m.sup.2/g, and MgCO.sub.3 has a flake-like structure.

[0024] Subsequently, an organic vehicle is prepared (S300).

[0025] The organic vehicle includes 1 to 20 wt % of a binder, 78 to 80 wt % of an organic solvent, and 0.1 to 2 wt % of a plasticizer. Here, ethyl cellulose (EC) is used as the binder, one of terpineol, alpha terpineol (a-terpineol), dihydro-terpineol, and dihydro-terpineol acetate is used as the organic solvent, and di-2-ethylhexyl phthalate (DOP) is used as the plasticizer.

[0026] Subsequently, an internal electrode composition of the multi-layer ceramic capacitor for a vehicle according to an embodiment of the present disclosure is prepared (S400). An internal electrode composition according to an embodiment is formed by mixing Ni of 79 to 91.9% by weight (wt %), Sn of 0.1 to 2.0 wt %, BaTiO.sub.3 of 7.5 to 15 wt %, and MgCO.sub.3 of 0.5 to 4.0 wt %.

[0027] Next, the obtained internal electrode composition of 35 to 80 wt %, an organic vehicle of 15.5 to 55 wt %, and a dispersant of 0.5 to 10 wt % are mixed (S500).

[0028] In the mixing method, 35 to 80 wt % of the internal electrode composition, 15.5 to 55 wt % of the organic vehicle, and 0.5 to 10 wt % of the dispersant are dispersed and mixed with a clear mixer, and nonylphenol ethoxylate phosphate ester is used as the dispersant.

[0029] When the internal electrode composition and the organic vehicle are dispersed and mixed with the dispersant in a 3-roll mill, the internal electrode composition and the organic vehicle are finally mixed with MDF, and then filtered to prepare a metal paste for an internal electrode (S600).

[0030] The filtration is primarily filtered using a 10 m filter and then secondarily filtered using a 1 to 3 m filter to prepare a metal paste for internal electrodes.

[0031] The multi-layer ceramic capacitor shown in FIG. 2 was prepared using the metal paste for an internal electrode thus obtained.

[0032] The multi-layer ceramic capacitor shown in FIG. 2 includes a ceramic fired body 100 and a pair of external electrodes 200 and 210.

[0033] The ceramic fired body 100 includes a dielectric 110 and a plurality of internal electrodes 120 and 121 formed to cross each other on the inside of the dielectric 110.

[0034] The pair of external electrodes 200 and 210 are selectively connected to the plurality of internal electrodes 120 and 121, respectively. For example, the external electrode 200 is connected to each of the plurality of internal electrodes 120, and the external electrode 210 is formed to be connected to each of the plurality of internal electrodes 121.

[0035] The thickness T of each of the internal electrodes 120 and 121 connected to the external electrodes 200 and 210 was 1 m or less, and was manufactured using the internal electrode metal paste including the internal electrode composition of the multi-layer ceramic capacitor for a vehicle according to the embodiment of the present disclosure described above.

[0036] The external electrodes 200 and 210 are formed by plating Ni on surfaces thereof using a wet barrel plating method and then plating Sn.

[0037] In order to test the product characteristics of the multi-layer ceramic capacitor manufactured using the internal electrode metal paste including the internal electrode composition of the multi-layer ceramic capacitor for a vehicle according to the embodiment of the present disclosure, Experimental Examples 1 to 3 were prepared as shown in Tables 1 to 3, respectively.

TABLE-US-00001 TABLE 1 BaTiO.sub.3 Ni (wt %) Sn (wt %) (wt %) MgCO.sub.3 (wt %) Experimental Comparative 92.5 0.0 7.5 0.0 Example 1 Example 1 Comparative 90.0 0.0 10.0 0.0 Example 2 Comparative 87.5 0.0 12.5 0.0 Example 3 Comparative 85.0 0.0 15.0 0.0 Example 4 Comparative 80.0 0.0 20.0 0.0 Example 5 [0038] Experimental Example 1 of Table 1 shows multi-layer ceramic capacitors prepared according to Comparative Examples 1 to 5. The multi-layer ceramic capacitors according to Comparative Examples 1 to 5 were manufactured in the same manner as the multi-layer ceramic capacitor shown in FIG. 2, but Ni and BaTiO.sub.3 were used as the internal electrode compositions used to form the plurality of internal electrodes 120 and 121.

TABLE-US-00002 TABLE 2 BaTiO.sub.3 MgCO.sub.3 Ni (wt %) Sn (wt %) (wt %) (wt %) Experimental Example 1 89.9 0.1 10 0.0 Example 2 Example 2 89.5 0.5 10 0.0 Example 3 89.1 1.0 10 0.0 Example 4 88.7 1.5 10 0.0 Example 5 88.2 2.0 10 0.0 Example 6 89.5 0.0 10 0.5 Example 7 89.1 0.0 10 1.0 Example 8 88.2 0.0 10 2.0 Example 9 87.3 0.0 10 3.0 Example 10 86.4 0.0 10 4.0 Example 11 88.6 1.0 10 0.5 Example 12 88.2 1.0 10 1.0 Example 13 87.3 1.0 10 2.0 Example 14 86.4 1.0 10 3.0 Example 15 85.6 1.0 10 4.0 Example 16 89.0 0.1 10 1.0 Example 17 88.6 0.5 10 1.0 Example 18 88.2 1.0 10 1.0 Example 19 87.8 1.5 10 1.0 Example 20 87.3 2.0 10 1.0 [0039] Experimental Example 2 of Table 2 shows multi-layer ceramic capacitors prepared according to Examples 1 to 20. The multi-layer ceramic capacitors according to Examples 1 to 20 were each prepared in the same manner as the multi-layer ceramic capacitor illustrated in FIG. 2, but Ni, Sn, BaTiO.sub.3, and MgCO.sub.3 were used as internal electrode compositions.

[0040] The multi-layer ceramic capacitors according to Examples 1 to 5 of Experimental Example 2 were prepared by changing the amount of Ni and Sn added while the amount of BaTiO.sub.3 added was fixed at 10 wt %, excluding MgCO.sub.3 from the internal electrode compositions.

[0041] The multi-layer ceramic capacitors according to Examples 6 to 10 of Experimental Example 2 were prepared by changing the amount of Ni and MgCO.sub.3 added while the amount of BaTiO.sub.3 added was fixed at 10 wt %, excluding Sn from the internal electrode compositions.

[0042] The multi-layer ceramic capacitors according to Examples 11 to 15 of Experimental Example 2 were prepared by changing the amount of Ni and MgCO.sub.3 added while the amount of BaTiO.sub.3 added was fixed at 10 wt %, and the amount of Sn added was fixed at 1 wt %, as the internal electrode compositions.

[0043] The multi-layer ceramic capacitors according to Examples 16 to 20 of Experimental Example 2 were prepared by changing the amount of Ni and Sn added while the amount of BaTiO.sub.3 added was fixed at 10 wt %, and the amount of MgCO.sub.3 added was fixed at 1 wt %, as the internal electrode compositions.

[0044] MgCO.sub.3 used in Experimental Example 2 had a flake-like structure.

TABLE-US-00003 TABLE 3 BaTiO.sub.3 MgCO.sub.3 Ni (wt %) Sn (wt %) (wt %) (wt %) Experimental Example 21 91.9 0.1 7.5 0.5 Example 3 Example 22 88.5 0.5 10.0 1.0 Example 23 84.5 1.0 12.5 2.0 Example 24 80.5 1.5 15.0 3.0 Example 25 74.1 2.0 20.0 4.0

[0045] Experimental Example 3 of Table 3 shows multi-layer ceramic capacitors prepared according to Examples 21 to 25. The multi-layer ceramic capacitors according to Examples 21 to 25 were each manufactured in the same manner as the multi-layer ceramic capacitor shown in FIG. 2. However, Ni, Sn, BaTiO.sub.3, and MgCO.sub.3 were used as internal electrode compositions, and each addition amount was changed as illustrated in Table 3, and MgCO.sub.3 of a flake-like structure was used.

[0046] The internal electrode composition of the multi-layer ceramic capacitor according to Example 21 of Experimental Example 3 used BaTiO.sub.3 of a specific surface area of 20 m.sup.2/g, and MgCO.sub.3 of a specific surface area of 35 m.sup.2/g, and a specific surface area of MgCO.sub.3 is 1.7 times as large as that of BaTiO.sub.3.

[0047] The internal electrode composition of the multi-layer ceramic capacitor according to Example 22 of Experimental Example 3 used BaTiO.sub.3 of a specific surface area of 60 m.sup.2/g, and MgCO.sub.3 of a specific surface area of 90 m.sup.2/g, and a specific surface area of MgCO.sub.3 is 1.5 times as large as that of BaTiO.sub.3.

[0048] The internal electrode composition of the multi-layer ceramic capacitor according to Example 23 of Experimental Example 3 used BaTiO.sub.3 of a specific surface area of 40 m.sup.2/g, and MgCO.sub.3 of a specific surface area of 80 m.sup.2/g, and a specific surface area of MgCO.sub.3 is 2.0 times as large as that of BaTiO.sub.3.

[0049] The internal electrode composition of the multi-layer ceramic capacitor according to Example 24 of Experimental Example 3 used BaTiO.sub.3 of a specific surface area of 30 m.sup.2/g, and MgCO.sub.3 of a specific surface area of 90 m.sup.2/g, and a specific surface area of MgCO.sub.3 is 3.0 times as large as that of BaTiO.sub.3.

[0050] The internal electrode composition of the multi-layer ceramic capacitor according to Example 25 of Experimental Example 3 used BaTiO.sub.3 of a specific surface area of 20 m.sup.2/g, and MgCO.sub.3 of a specific surface area of 100 m.sup.2/g, and a specific surface area of MgCO.sub.3 is 5.0 times as large as that of BaTiO.sub.3.

[0051] Characteristics tests of Capacitance [/F], Dissipation Factor (DF) [%], Breakdown Voltage (BDV) [V/m], Coverage [%], and Mean Time To Failure (MTTF) [year] were performed for the multi-layer ceramic capacitors prepared according to Experimental Examples 1 to 3 described above, and the results are shown in Tables 4 to 6.

TABLE-US-00004 TABLE 4 Capacitance DF BDV Coverage [F] [%] [V/m] [%] MTTF Experimental Comparative 23.5 5.8 93 85.0 24 Example 1 Example 1 Comparative 22.6 5.2 112 92.5 57 Example 2 Comparative 21.8 4.8 113 93.1 60 Example 3 Comparative 20.5 4.2 117 93.5 62 Example 4 Comparative 18.5 4.0 118 94.2 68 Example 5

[0052] As shown in Table 4, it can be seen that the multi-layer ceramic capacitors prepared according to Comparative Examples 1 to 5 of Experimental Example 1 increased BDV, coverage, and MTTF characteristics but decreased capacitance or DF when Ni was reduced and the amount of BaTiO.sub.3 added was increased in the internal electrode compositions.

TABLE-US-00005 TABLE 5 Capaci- Cover- tance DF BDV age [F] [%] [V/m] [%] MTTF Experimental Example 1 22.4 5.1 114 93.0 88 Example 2 Example 2 22.1 4.9 115 93.4 105 Example 3 22.0 4.9 118 93.8 148 Example 4 20.1 4.1 118 92.7 150 Example 5 19.4 4.0 120 92.6 155 Example 6 22.7 5.3 113 93.2 68 Example 7 22.9 5.4 117 93.5 92 Example 8 20.5 4.2 117 94.2 95 Example 9 19.4 4.0 118 94.8 98 Example 10 18.5 4.0 120 95.2 105 Example 11 22.5 5.1 118 93.8 148 Example 12 20.6 4.3 127 93.7 146 Example 13 19.9 4.1 127 93.5 148 Example 14 19.4 4.0 128 94.2 150 Example 15 17.7 4.1 129 94.8 153 Example 16 22.6 5.2 118 93.4 108 Example 17 22.8 5.3 128 94.2 145 Example 18 20.6 4.3 127 93.7 146 Example 19 19.9 4.1 129 94.8 155 Example 20 19.7 4.1 126 95.1 165

[0053] As shown in Table 5, the multi-layer ceramic capacitors prepared according to Examples 1 to 20 of Experimental Example 2 show the similar rates of change in capacitance or DF depending on the amount of Ni and BaTiO.sub.3 added in the internal electrode composition, but show enhanced characteristics of BDV, coverage, and MTTF, when compared to the Comparison Examples 1 to 5 of Experimental Example 1.

TABLE-US-00006 TABLE 6 Capaci- tance DF BDV Coverage [F] [%] [V/m] [%] MTTF Experimental Example 20.6 5.20 121 94.4 100 Example 3 21 Example 21.8 4.9 121 94.2 135 22 Example 21.2 4.2 127 93.9 140 23 Example 22.0 4.4 127 95.3 151 24 Example 21.0 5.1 129 95.5 145 25

[0054] As shown in Table 6, the multi-layer ceramic capacitors prepared according to Examples 21 to 25 of Experimental Example 3 show the similar rates of change in capacitance or DF depending on the amount of Ni and BaTiO.sub.3 added in the internal electrode composition, when compared to the Comparison Examples 1 to 5 of Experimental Example 1, but show enhanced characteristics of BDV, coverage, and MTTF, as in Examples 1 to 20 of Experimental Example 2, when compared to the Comparison Examples 1 to 5 of Experimental Example 1.

[0055] As described above, the internal electrode composition of a multi-layer ceramic capacitor for a vehicle, according to the present disclosure, prevents coverage characteristics from being reduced due to a sintering delay of an internal electrode, while minimizing the content of a ceramic base substance such as BaTiO.sub.3 for controlling firing shrinkage rates between Ni metal and dielectric ceramic generated during sintering, and prevents the diffusion of BaTiO.sub.3 to the dielectric, thereby preventing the thickness of the dielectric from increasing, and thus increasing the withstand voltage or capacity of the multi-layer ceramic capacitor or reducing the leakage current, to accordingly improve reliability by enhancing high-temperature insulation resistance characteristics.

[0056] In addition, the internal electrode composition of a multi-layer ceramic capacitor for a vehicle, according to the present disclosure, minimizes sintering and reactivity with the dielectric by adding MgCO.sub.3 to a ceramic base substance, although a less amount of BaTiO.sub.3, which is used as the ceramic base substance, is added, to thereby improve the reliability of multi-layer ceramic capacitor products that may increase the capacity of multi-layer ceramic capacitors or reduce leakage current. In addition, the internal electrode composition of a multi-layer ceramic capacitor for a vehicle, according to the present disclosure, forms an insulating active layer (not shown) between a dielectric and an internal electrode interface by adding tin (Sn) to metal powder, to thereby increase the reliability of the product of the multi-layer ceramic capacitor.

[0057] The internal electrode composition of a multi-layer ceramic capacitor for a vehicle according to the present disclosure is applied to the industry of manufacturing a multi-layer component device.