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US-20260128223-A1 - MULTILAYER CERAMIC CAPACITOR

US20260128223A1US 20260128223 A1US20260128223 A1US 20260128223A1US-20260128223-A1

Abstract

A multilayer ceramic capacitor includes an outer electrode and a multilayer body including a plurality of dielectric layers and a plurality of inner electrode layers that are stacked on top of each other. The outer electrode includes a plating layer and a base electrode layer. The base electrode layer includes glass. The glass includes an alkaline-earth metal. In a thickness direction of the base electrode layer, when a mass ratio of the alkaline-earth metal in the glass present in a central portion is 100, a mass ratio of the alkaline-earth metal in the glass present in a near-surface portion adjacent to the plating layer is 90 or more and less than 100.

Inventors

  • Kazuya Taga
  • Yosuke TERASHITA
  • Takuya SASAKURA

Assignees

  • MURATA MANUFACTURING CO., LTD.

Dates

Publication Date
20260507
Application Date
20251230
Priority Date
20230703

Claims (19)

  1. 1 . A multilayer ceramic capacitor comprising: an outer electrode; and a multilayer body including a plurality of dielectric layers and a plurality of inner electrode layers that are stacked on top of each other; wherein the outer electrode includes a plating layer and a base electrode layer; the base electrode layer includes glass, the glass includes an alkaline-earth metal; and in a thickness direction of the base electrode layer, when a mass ratio of the alkaline-earth metal in the glass present in a central portion is 100, a mass ratio of the alkaline-earth metal in the glass present in a near-surface portion adjacent to the plating layer is 90 or more and less than 100.
  2. 2 . The multilayer ceramic capacitor according to claim 1 , wherein in the base electrode layer, the mass ratio of the alkaline-earth metal in the glass present in the near-surface portion adjacent to the plating layer is 96 or more and 98 or less.
  3. 3 . The multilayer ceramic capacitor according to claim 1 , wherein the glass includes borosilicate glass.
  4. 4 . The multilayer ceramic capacitor according to claim 3 , wherein the glass further includes an alkali metal.
  5. 5 . The multilayer ceramic capacitor according to claim 3 , wherein the glass further includes copper oxide.
  6. 6 . The multilayer ceramic capacitor according to claim 1 , wherein the base electrode layer further includes at least one conductive component selected from the group consisting of copper, nickel, and a copper-nickel alloy.
  7. 7 . The multilayer ceramic capacitor according to claim 1 , wherein in the thickness direction of the base electrode layer, when the mass ratio of the alkaline-earth metal in the glass present in the central portion is 100, a ratio of the alkaline-earth metal in the glass present in a near-surface portion adjacent to the multilayer body is 105 or more and 115 or less.
  8. 8 . The multilayer ceramic capacitor according to claim 1 , wherein the base electrode layer is a sintered body layer of a conductive paste including a glass composition; the glass composition includes Li 2 O, Na 2 O, Cao, Bao, and B 2 O 3 , and a mass ratio of a total of Li 2 O, Na 2 O, Cao, and Bao to B 2 O 3 in the glass composition is 1.17 to 2.61.
  9. 9 . The multilayer ceramic capacitor according to claim 1 , wherein the alkaline-earth metal includes at least one of calcium, strontium, or barium.
  10. 10 . The multilayer ceramic capacitor according to claim 9 , wherein the alkaline-earth metal further includes magnesium.
  11. 11 . The multilayer ceramic capacitor according to claim 4 , wherein the alkali metal includes at least one of lithium, sodium, or potassium.
  12. 12 . The multilayer ceramic capacitor according to claim 1 , wherein the glass further includes zinc oxide, aluminum oxide, or bismuth oxide.
  13. 13 . The multilayer ceramic capacitor according to claim 1 , wherein a thickness of the base electrode layer is 10 μm or more and 50 μm or less.
  14. 14 . The multilayer ceramic capacitor according to claim 1 , wherein a thickness of the base electrode layer is 15 μm or more and 40 μm or less.
  15. 15 . The multilayer ceramic capacitor according to claim 1 , wherein the plating layer incudes nickel, copper, silver, gold, or tin, or an alloy of nickel, copper, silver, gold, or tin.
  16. 16 . The multilayer ceramic capacitor according to claim 1 , wherein the plating layer includes a plurality of layers including different materials.
  17. 17 . The multilayer ceramic capacitor according to claim 1 , wherein the plating layer includes a Ni plating layer and a Sn plating layer.
  18. 18 . The multilayer ceramic capacitor according to claim 1 , wherein the plating layer includes an upper plating layer and a lower plating layer each with a thickness of 0.5 μm or more and 10 μm or less.
  19. 19 . The multilayer ceramic capacitor according to claim 1 , wherein the multilayer ceramic capacitor has a dimension in a length direction of 2.0 mm or less, a dimension in a width direction of 1.25 mm or less, and a dimension in a stacking direction of 1.25 mm or less.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to Japanese Patent Application No. 2023-109180 filed on Jul. 3, 2023 and is a Continuation Application of PCT Application No. PCT/JP2024/021452 filed on Jun. 13, 2024. The entire contents of each application are hereby incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to multilayer ceramic capacitors. 2. Description of the Related Art As described in Japanese Unexamined Patent Application Publication No. 2021-019018, an outer electrode of a multilayer ceramic capacitor generally includes a base electrode layer formed on a surface of a multilayer body such as a ceramic body, and a plating layer provided on the base electrode layer. For the purpose of densification, the base electrode layer is often formed from a conductive paste including glass. The glass used for the base electrode layer is designed so as to satisfy various demand characteristics, such as filling pores inside the outer electrode to form a dense film, acting as an aid in the sintering process, adhering to the body after baking, and the glass itself having chemical durability. SUMMARY OF THE INVENTION In a multilayer ceramic capacitor, when a base electrode layer of an outer electrode includes glass, solder popping tends to occur. Solder popping is a phenomenon in which, for example, when the multilayer ceramic capacitor is mounted on a circuit board and fixed by soldering, moisture and a plating solution that have entered the base electrode layer rapidly evaporate due to the heat of soldering, and the outside solder spatters, which may cause a short-circuit failure. Example embodiments of the present invention provide multilayer ceramic capacitors each including an outer electrode that is less likely to cause solder popping. A multilayer ceramic capacitor according to an example embodiment of the present disclosure includes an outer electrode and a multilayer body including a plurality of dielectric layers and a plurality of inner electrode layers that are stacked on top of each other. The outer electrode includes a plating layer and a base electrode layer. The base electrode layer includes glass. The glass includes an alkaline-earth metal. In a thickness direction of the base electrode layer, when a mass ratio of the alkaline-earth metal in the glass present in a central portion is 100, a mass ratio of the alkaline-earth metal in the glass present in a near-surface portion adjacent to the plating layer is 90 or more and less than 100. According to example embodiments of the present disclosure, multilayer ceramic capacitors each including an outer electrode that is less likely to cause solder popping are provided. The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating the appearance of a multilayer ceramic capacitor according to an example embodiment of the present disclosure. FIG. 2 is a sectional view of the multilayer ceramic capacitor in FIG. 1 taken along line II-II. FIG. 3 is a sectional view of the multilayer ceramic capacitor in FIG. 1 taken along line III-III. FIG. 4 is a sectional view illustrating a layer configuration of an outer electrode. FIG. 5 is a schematic view for explaining the microstructure of a base electrode layer. FIG. 6 is a sectional view for explaining a central portion, a near-surface portion, and a near-interface portion of the base electrode layer. DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS Hereinafter, multilayer ceramic capacitor according to example embodiments of the present disclosure will be described with reference to figures. In the following description of example embodiments, like or corresponding elements, structures, or features in the figures are denoted by like reference numerals and will not be repeatedly described. The multilayer ceramic capacitor includes an outer electrode and a multilayer body including a plurality of dielectric layers and a plurality of inner electrode layers that are stacked on top of each other. The outer electrode is positioned such that the base electrode layer side is located on the multilayer body. FIG. 1 is a perspective view illustrating the appearance of a multilayer ceramic capacitor according to an example embodiment of the present disclosure. FIG. 2 is a sectional view of the multilayer ceramic capacitor in FIG. 1 taken along line II-II. FIG. 3 is a sectional view of the multilayer ceramic capacitor in FIG. 1 taken along line III-III. As illustrated in FIGS. 1 to 3, a multilayer ceramic capacitor 100 according to an example embodiment of the present disclosure includes a multilayer body 110 and an outer electrode 120. As illustrated in FIGS. 2 and 3,