CN115458331A - Multilayer ceramic capacitor and preparation method thereof - Google Patents
Multilayer ceramic capacitor and preparation method thereof Download PDFInfo
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- CN115458331A CN115458331A CN202211039601.4A CN202211039601A CN115458331A CN 115458331 A CN115458331 A CN 115458331A CN 202211039601 A CN202211039601 A CN 202211039601A CN 115458331 A CN115458331 A CN 115458331A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/018—Dielectrics
- H01G4/06—Solid dielectrics
- H01G4/08—Inorganic dielectrics
- H01G4/12—Ceramic dielectrics
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/005—Electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/224—Housing; Encapsulation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/228—Terminals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/30—Stacked capacitors
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
- Ceramic Capacitors (AREA)
Abstract
The invention relates to the technical field of capacitors and discloses a multilayer ceramic capacitor and a preparation method thereof, wherein the multilayer ceramic capacitor comprises a ceramic body and two terminal electrodes, wherein each terminal electrode comprises a first electrode part covered on the end surface of the ceramic body and a second electrode part extending to the side surface of the ceramic body; the first internal electrode extends to the side surface of the ceramic body and is connected with a second electrode part in one terminal electrode; the second internal electrode extends to the side surface of the ceramic body and is connected with a second electrode part in the other end electrode; the insulating layer covered on the terminal electrode comprises a first insulating part arranged on the first electrode part and a second insulating part covered on the second electrode part, the first insulating part is covered with a conducting layer, the conducting layer is provided with a connecting part matched with a connecting through hole of the first insulating part, and the conducting layer is covered with a welding layer; the long path of the plating solution permeation in the invention can prevent the plating solution from reaching the inner electrode without causing insulation resistance reduction, reduce the overall installation height on a circuit board, and can automatically perform electric performance sorting.
Description
Technical Field
The invention relates to the technical field of capacitors, in particular to a multilayer ceramic capacitor and a preparation method thereof.
Background
At present, the end electrode of a multilayer ceramic capacitor of a base metal electrode is generally in a copper-nickel-tin three-layer structure, a copper layer is formed on a capacitor ceramic body by adopting a sintering and infiltrating process, and then a nickel layer and a tin layer are sequentially formed on the copper layer by adopting an electroplating method. The copper layer is generally formed by sintering a copper paste in a neutral atmosphere, and organic components in the copper paste are difficult to be removed in an atmosphere of low oxygen partial pressure, resulting in poor copper layer compactness, and then a plating solution penetrates through a very thin copper layer (for example, 5 μm to 60 μm) during electroplating, and further penetrates into the ceramic body from a gap between the internal electrode and the ceramic body, resulting in a decrease in insulation resistance of the multilayer ceramic capacitor, and in the severe case, a short circuit may occur. In order to prevent the plating solution from permeating into the copper layer, a method of covering an insulating layer on the copper layer to block the plating solution is adopted in the industry, but because the insulating layer is not conductive, automatic electric performance sorting cannot be carried out on the multilayer ceramic capacitor, and thus large-scale production is difficult to realize.
In addition, the terminal electrode not only completely covers the end face of the multilayer ceramic capacitor, but also bends and extends to four side faces of the multilayer ceramic capacitor at the edge of the end face, so that after the multilayer ceramic capacitor is welded on a circuit board, soldering tin can enter the lower part of the multilayer ceramic capacitor and jack the multilayer ceramic capacitor, the mounting position of the multilayer ceramic capacitor is high, and the space saving for the whole machine is not facilitated.
Disclosure of Invention
The invention aims to provide a multilayer ceramic capacitor which has a long plating solution permeation path, can prevent a plating solution from reaching an inner electrode, does not cause insulation resistance reduction, reduces the mounting height of the whole on a circuit board and can automatically sort electric properties and a preparation method thereof.
In order to achieve the above object, an aspect of the present invention provides a multilayer ceramic capacitor including a ceramic body and two terminal electrodes respectively disposed at both ends of the ceramic body, the terminal electrodes including a first electrode portion covering an end surface of the ceramic body and second electrode portions extending to four side surfaces of the ceramic body, and ends of the two second electrode portions being disposed opposite to each other with a distance therebetween;
the ceramic body comprises dielectric layers which are arranged in a stacked mode and inner electrodes which are arranged between two adjacent dielectric layers, each inner electrode comprises a first inner electrode and a second inner electrode which are arranged alternately, the first inner electrodes extend to the side face of the ceramic body to form first inner electrode leading-out ends, the first inner electrode leading-out ends are connected with a second electrode part in one terminal electrode, and the first inner electrodes are spaced from two end faces of the ceramic body; the second inner electrode extends to the side face of the ceramic body to form a second inner electrode leading-out end, the second inner electrode leading-out end is connected with a second electrode part in the other end electrode, and the second inner electrode is away from two end faces of the ceramic body;
the end electrode covers the insulating layer, the insulating layer is including setting up first insulating part on the first electrode portion and cover second insulating part on the second electrode portion, just second insulating part extends to on the side of ceramic body, the middle part of first insulating part is equipped with the connection via hole, first insulating part coats and is stamped the conducting layer, the middle part arch of conducting layer be equipped with connect via hole complex connecting portion, the conducting layer covers and is equipped with the welding layer.
In a preferred embodiment of the present invention, the four side surfaces of the ceramic body include two first side surfaces disposed opposite to each other and two second side surfaces disposed opposite to each other, the internal electrodes are T-shaped, the internal electrodes extend to the two first side surfaces and are connected to the second electrode portion, and the internal electrodes are spaced apart from the two end surfaces and the two second side surfaces of the ceramic body.
In a preferred embodiment of the present invention, the shortest distance between the internal electrode lead-out terminal and the end surface of the ceramic body adjacent thereto is represented as d1; the d1 is 10-30% of the length of the ceramic body; recording the distance between the end face of the tail end of the second electrode part and the end face of the ceramic body close to the end face as d2; the d2 is 15-35% of the length of the ceramic body.
As a preferable aspect of the present invention, the second electrode portion of one of the terminal electrodes completely covers the first inner-electrode lead; and the second electrode part in the other terminal electrode completely covers the second inner electrode leading-out terminal.
As a preferable aspect of the present invention, the second electrode portion of one of the terminal electrodes partially covers the first inner electrode lead-out terminal along a length direction of the ceramic body, and the second insulating portion covering the one of the terminal electrodes completely covers the first inner electrode lead-out terminal; and the second electrode part in the other terminal electrode partially covers the second inner electrode leading-out end along the length direction of the ceramic body, and the second insulating part covered on the other terminal electrode completely covers the second inner electrode leading-out end.
As a preferable scheme of the present invention, the soldering layer is a single-layer metal layer, and the material of the soldering layer is one of tin, gold, or silver; the thickness of the welding layer is 5-10 mu m.
As a preferable scheme of the present invention, the welding layer includes an inner metal layer and an outer metal layer, the inner metal layer covers the conductive layer, and the material of the inner metal layer is nickel or nickel-chromium alloy; the outer metal layer is made of one of tin, gold or silver; the thickness of the inner metal layer is 2-5 μm; the thickness of the outer metal layer is 5-10 μm.
In a preferred embodiment of the present invention, the insulating layer is made of ceramic or resin, and the insulating layer has a thickness of 5 to 20 μm.
As a preferable scheme of the present invention, the material of the conductive layer is one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy, or indium-gallium alloy, and the thickness of the conductive layer is 0.1 μm to 0.5 μm.
In addition, another aspect of the present invention also provides a method for manufacturing a multilayer ceramic capacitor, comprising the steps of:
and 5, arranging a welding layer on the conductive layer.
Compared with the prior art, the multilayer ceramic capacitor and the preparation method thereof have the beneficial effects that:
the welding layer is arranged at the position opposite to the end face of the ceramic body, the inner electrode is led out from the side face of the ceramic body, meanwhile, the terminal electrode in the corresponding area is completely covered by the insulating layer or the leading-out end of the inner electrode is completely covered by the insulating layer, so that the plating solution cannot directly permeate; the conducting layer and the welding layer do not cover the second insulating part, so that when the multilayer ceramic capacitor is welded on a circuit board, the second insulating part can be in direct contact with the welding pad and does not have tin, and the tin can be prevented from entering the lower part, so that the mounting height of the multilayer ceramic capacitor is reduced, and the space is effectively saved; meanwhile, the welding layer, the conducting layer, the end electrode and the inner electrode sequentially form a conducting path, and automatic electric performance sorting of the multilayer ceramic capacitor is facilitated.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below.
FIG. 1 is a schematic view showing a structure in which a conventional multilayer ceramic capacitor is soldered to a wiring board;
FIG. 2 is a schematic view showing a plating solution penetration path of a conventional multilayer ceramic capacitor;
FIG. 3 is a perspective view of a multilayer ceramic capacitor according to the present invention;
FIG. 4 is a longitudinal sectional view of a multilayer ceramic capacitor according to the present invention;
FIG. 5 is a transverse sectional view of a multilayer ceramic capacitor provided by the present invention;
FIG. 6 is an exploded view of a multilayer ceramic capacitor according to the present invention;
FIG. 7 is a schematic view of a multilayer ceramic capacitor according to the present invention soldered to a wiring board;
FIG. 8 is a schematic view showing a plating solution penetration path of a multilayer ceramic capacitor provided by the present invention;
in the figure, 1 is a ceramic body; 11 is the end face of the ceramic body; 12 is a first side face; 13 is a second side; 14 is a dielectric layer; 15 is an inner electrode; 2 is a terminal electrode; 21 is a first electrode portion; 22 is a second electrode portion; 3 is an insulating layer; 31 is a first insulating portion; 32 is a second insulating part; 4 is a conductive layer; 41 is a connecting part; 5 is a welding layer; 6 is a circuit board; 61 is a bonding pad; 62 is solder.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
As shown in fig. 3 to 7, a multilayer ceramic capacitor according to a preferred embodiment of the present invention includes a ceramic body 1 and two terminal electrodes 2 respectively disposed at two ends of the ceramic body 1, the ceramic body 1 being a rectangular parallelepiped; the terminal electrode 2 comprises a first electrode part 21 covering the end face 11 of the ceramic body 1 and second electrode parts 22 extending to four side faces of the ceramic body 1, the tail ends of the two second electrode parts 22 are oppositely arranged, and a distance is reserved between the two second electrode parts; the ceramic body 1 comprises dielectric layers 14 which are arranged in a stacked mode and inner electrodes 15 which are arranged between two adjacent dielectric layers 14, each inner electrode 15 comprises a first inner electrode and a second inner electrode which are arranged alternately, each first inner electrode extends to the side face of the ceramic body 1 to form a first inner electrode leading-out end, each first inner electrode leading-out end is connected with a second electrode part 22 in one terminal electrode 2, and the first inner electrodes are spaced from two end faces of the ceramic body 1; the second internal electrode extends to the side surface of the ceramic body 1 to form a second internal electrode leading-out end, the second internal electrode leading-out end is connected with a second electrode part 22 in the other end electrode 2, the second internal electrode is separated from two end surfaces of the ceramic body 1, and the shortest distance between the internal electrode 15 and the end surface 11 of the ceramic body 1 is preferably 5-10% of the length of the ceramic body 1; if the distance is too small, a gap is likely to occur in the end face 11, and the plating solution penetrates from the gap to the inner electrode 15.
The terminal electrode 2 is covered with an insulating layer 3, the insulating layer 3 comprises a first insulating part 31 arranged on the first electrode part 21 and a second insulating part 32 covered on the second electrode part 22, and the second insulating part 32 extends to the side surface of the ceramic body 1; a connecting via hole is formed in the middle of the first insulating portion 31, a conductive layer 4 covers the first insulating portion 31, a connecting portion 41 matched with the connecting via hole is convexly formed in the middle of the conductive layer 4, and the purpose of arranging the conductive layer 4 is to form electric connection with the terminal electrode 2 and metalize the first insulating portion 31 so as to prepare a welding layer 5 on a region corresponding to the first insulating portion 31; the conducting layer 4 is covered with a welding layer 5, and the welding layer 5 is used for improving the welding performance of the multilayer ceramic capacitor.
In the present embodiment, the second electrode portion 22 of one of the terminal electrodes 2 completely covers the first inner electrode lead, and the second insulating portion 32 completely covers the second electrode portion 22 and extends to the side surface of the ceramic body 1; the second electrode part 22 of the other terminal electrode 2 completely covers the second inner electrode lead-out terminal, and the second insulating part 32 completely covers the second electrode part 22 and extends to the side surface of the ceramic body 1, so that the second insulating part 32 fully covers the second electrode part 22 to prevent the plating solution from penetrating into the inner electrode lead-out terminal.
Of course, in other embodiments, the second electrode portion 22 of one of the terminal electrodes 2 partially covers the first inner electrode lead along the length direction of the ceramic body, and the second insulating portion 32 covering one of the terminal electrodes 2 completely covers the first inner electrode lead; the second electrode portion 22 of the other terminal electrode 2 partially covers the second inner electrode terminal along the length direction of the ceramic body 1, and the second insulating portion 32 covering the other terminal electrode 2 completely covers the second inner electrode terminal, so that the second insulating portion 32 not only covers the second electrode portion 22 sufficiently, but also covers the portion of the inner electrode terminal still exposed, so that the plating solution can be prevented from penetrating into the inner electrode terminal.
Illustratively, the material of the terminal electrode 2 is copper; the thickness of the terminal electrode 2 is preferably 5 to 60 μm; if the thickness of the terminal electrode 2 is too small, the continuity of the copper layer becomes poor to be conductive, and if the thickness of the terminal electrode 2 is too large, it is not good to reduce the volume of the multilayer ceramic capacitor.
Illustratively, the four side surfaces of the ceramic body 1 include two first side surfaces 12 disposed opposite to each other and two second side surfaces 13 disposed opposite to each other, the first and second internal electrodes are both T-shaped, the first internal electrodes respectively extend to the two first side surfaces 12 in one end of the ceramic body 1 and are connected to the second electrode portion 22, and the first internal electrodes have distances from the two end surfaces of the ceramic body 1 and the two second side surfaces 13; the second internal electrodes extend to the two first side surfaces 12 at the other end of the ceramic body 1 and are connected to the second electrode part 22, and the second internal electrodes are spaced from the two end surfaces of the ceramic body 1 and the two second side surfaces 13; in the present embodiment, the two first side surfaces 12 are a front side surface and a rear side surface respectively; the two second side surfaces 13 are an upper side surface and a lower side surface, respectively.
Illustratively, the shortest distance between the internal electrode lead-out terminal and the end surface 11 of the ceramic body 1 close thereto is denoted as d1; the d1 is 10-30% of the length of the ceramic body 1; if d1 is too small, the effect of preventing the plating solution from penetrating is insufficient, and if d1 is too large, it is inconvenient to connect the inner electrode 15 and the second electrode portion 22.
Exemplarily, the distance between the end face of the second electrode portion 22 and the end face 11 of the ceramic body 1 adjacent thereto is denoted as d2; the d2 is 15-35% of the length of the ceramic body 1; if d2 is too small, the second electrode portion 22 cannot be reliably connected to the internal electrode 15 or the contact resistance increases, and if d2 is too large, the two terminal electrodes 2 are easily short-circuited.
As shown in fig. 8, the penetration path of the plating solution in the multilayer ceramic capacitor in this embodiment is indicated by an arrow in fig. 8, and the dotted line frame indicates that the penetration of the plating solution into the position causes a decrease in the insulation resistance, and the penetration path of the plating solution is long, and the plating solution cannot reach the inner electrode terminals exposed on the first side surface of the ceramic body 1, so that the decrease in the insulation resistance of the multilayer ceramic capacitor is not caused. As shown in fig. 2, the penetration path of the plating solution during electroplating of the conventional multilayer ceramic capacitor is indicated by an arrow in fig. 2, and the dotted line frame indicates that the penetration of the plating solution to the position causes the insulation resistance to be reduced.
In this embodiment, the welding layer 5 includes an inner metal layer and an outer metal layer, the inner metal layer covers the conductive layer 4, the inner metal layer is made of nickel or nickel-chromium alloy, the thickness of the inner metal layer is 2 μm to 5 μm, and the inner metal layer is used to protect the conductive layer 4 and the area of the terminal electrode 2 not covered by the first insulating portion 31 during welding, so as to prevent leaching; the outer metal layer is made of one of tin, gold or silver, the thickness of the outer metal layer is 5-10 mu m, and the outer metal layer plays a role in assisting welding.
In other embodiments, the soldering layer 5 is a single metal layer, and the material of the soldering layer 5 is one of tin, gold, or silver; the thickness of the welding layer 5 is 5-10 μm.
As shown in fig. 1, the schematic structural diagram of the multilayer ceramic capacitor of the prior art welded to the circuit board 6 ', four side surfaces of the multilayer ceramic capacitor of the prior art can be used as welding surfaces, and since the whole outer layer of the terminal electrode 2 ' is a tin layer, the soldering tin 62 ' can enter the lower part of the multilayer ceramic capacitor to jack up the multilayer ceramic capacitor, so that the installation position of the multilayer ceramic capacitor becomes high, and the space saving for the whole machine is not facilitated.
As shown in fig. 7, a schematic structural diagram of the multilayer ceramic capacitor according to the embodiment of the present invention soldered to a circuit board 6 is shown, four side surfaces of the multilayer ceramic capacitor according to the embodiment of the present invention can be used as soldering surfaces, and the conductive layer 4 and the soldering layer 5 do not cover the second insulating portion 32, so that when the multilayer ceramic capacitor is soldered to the circuit board 6, the second insulating portion 32 can be in direct contact with a pad 61 and is not coated with tin, and a soldering tin 62 can be prevented from entering below, thereby reducing the mounting height of the multilayer ceramic capacitor and saving space for the whole machine; further, the solder layer 5 completely covers the first insulating layer 31, that is, the solder layer 5 covers the peripheral area of the end face of the multilayer ceramic capacitor, so that the solder 62 is easily attached to the end face of the multilayer ceramic capacitor, and a good soldering effect is achieved. Meanwhile, after the multilayer ceramic capacitor is welded on the circuit board 6, the bonding pad 61, the soldering tin 62, the welding layer 5, the conducting layer 4, the terminal electrode 2 and the inner electrode 15 form a conducting path in sequence, and the multilayer ceramic capacitor is guaranteed to play a circuit function.
Illustratively, the material of the insulating layer 3 is ceramic or resin, and the thickness of the insulating layer 3 is 5 μm to 20 μm; if the thickness of the insulating layer 3 is too small, the effect of preventing the plating solution from penetrating is not good, and if the thickness of the insulating layer 3 is too large, it is not good to reduce the volume of the multilayer ceramic capacitor. Further, the shortest distance between the outer peripheral edge of the connecting via hole in the middle of the first insulating portion 31 and the outer peripheral edge of the end surface 11 of the ceramic body 1 close to the connecting via hole is 20% to 90% of the distance between the two second side surfaces 13; if the distance is too small, the plating solution penetration preventing effect is insufficient, and if the distance is too large, the connection via hole is too small, and the contact resistance between the terminal electrode 2 and the conductive layer 4 increases.
Illustratively, the material of the conductive layer 4 is one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy or indium-gallium alloy; the thickness of the conductive layer 4 is 0.1 μm to 0.5 μm, and if the thickness of the conductive layer 4 is too small, continuity becomes poor and it is not preferable to conduct electricity, and if the thickness of the conductive layer 4 is too large, it is not preferable to reduce the volume of the multilayer ceramic capacitor. Further, the shortest distance between the peripheral edge of the conductive layer 4 and the peripheral edge of the end face 11 of the ceramic body 1 adjacent thereto is less than 20% of the distance between the two second side faces 13, so that tin is applied to the end face 11 when the multilayer ceramic capacitor is soldered. In the present embodiment, the conductive layer 4 completely covers the first insulating portion 31. In other embodiments, the conductive layer 4 may also partially cover the first insulating portion 31. The thickness of the conductive layer 4 is a thickness covering the first insulating portion 31 (i.e., a thickness not covering the connecting portion 41).
In addition, the invention also provides a preparation method of the multilayer ceramic capacitor, which comprises the following steps:
the step 1 comprises the following specific steps:
step 1.1, preparing a ceramic diaphragm by taking the ceramic slurry as a raw material, wherein the ceramic diaphragm is the dielectric layer 14; the method specifically comprises the following steps: mixing ceramic powder, an adhesive and an organic solvent, uniformly dispersing by adopting a ball milling or sanding method to obtain ceramic slurry, and then casting the ceramic slurry into a ceramic membrane; wherein, the ceramic powder adopts ceramic materials commonly used by multilayer ceramic capacitors such as barium titanate, calcium zirconate and the like.
Step 1.2, printing inner electrode 15 slurry on the ceramic membrane to form an inner electrode 15 pattern, and drying the inner electrode 15 slurry to obtain the ceramic membrane with the inner electrode 15; the method specifically comprises the following steps: printing the inner electrode 15 slurry on the ceramic membrane by adopting a screen printing or gravure printing method to form an inner electrode 15 pattern on one side surface of the ceramic membrane, and drying the inner electrode 15 slurry to obtain the ceramic membrane with the inner electrode 15; wherein, the inner electrode 15 slurry adopts nickel slurry;
step 1.3, laminating a plurality of ceramic diaphragms with inner electrodes 15 according to a preset number, and covering protective layers on the upper side and the lower side of the laminated structure to obtain a ceramic substrate; wherein the protective layer comprises at least one ceramic membrane obtained in the step 1.1; the number of laminated ceramic sheets having the internal electrodes 15 is not limited, but is preferably 80 or more layers in order to obtain a high capacitance;
step 1.4, compressing and cutting the ceramic substrate to obtain a plurality of ceramic plates; the method specifically comprises the following steps: compacting the ceramic substrate by an isostatic pressing method, and then cutting the ceramic substrate longitudinally and transversely according to a preset size to obtain a plurality of cuboid-shaped ceramic plates;
step 1.5, removing glue from the ceramic sheets and sintering to obtain a ceramic body 1, wherein four side surfaces of the ceramic body 1 comprise two first side surfaces 12 arranged oppositely and two second side surfaces 13 arranged oppositely, and the first internal electrode leading-out end and the second internal electrode leading-out end are respectively exposed out of the front end and the rear end of the two first side surfaces of the ceramic body 1; the method comprises the following specific operations: firstly, carrying out glue discharging operation, wherein the glue discharging operation is to heat the ceramic wafer to 250-350 ℃ in the air and preserve heat for 0.5-3 hours to discharge the adhesive contained in the ceramic wafer, or to heat the ceramic wafer to 350-600 ℃ in nitrogen and preserve heat for 2-6 hours to discharge the adhesive contained in the ceramic wafer. And then sintering, namely heating the ceramic wafer to 1100-1300 ℃ in a reducing atmosphere formed by humidified mixed gas of nitrogen and hydrogen (the volume of the hydrogen is 0.1-3% of that of the nitrogen), preserving heat for 0.5-3 hours, and sintering the ceramic wafer into ceramic to obtain the ceramic body 1.
and 5, arranging a welding layer 5 on the conductive layer 4 by an electroplating method.
To sum up, the welding layer 5 of the embodiment of the present invention is disposed at a position facing the end surface 11 of the ceramic body 1, and the inner electrode 15 is led out from the side surface of the ceramic body 1, and meanwhile, the terminal electrode 2 of the corresponding region is completely covered by the insulating layer 3 or the leading-out end of the inner electrode 15 is completely covered by the insulating layer 3, so that the plating solution cannot directly permeate, if the plating solution is to permeate into the leading-out end of the inner electrode 15, the plating solution can only enter from the region where the terminal electrode 2 is not covered by the insulating layer 3, the permeation direction of the plating solution can only be along the layer surface of the terminal electrode 2, and the region where the terminal electrode 2 is not covered by the insulating layer 3 is far away from the leading-out end of the inner electrode 15, so that the permeation surface of the plating solution is narrow and the permeation path is long, and therefore the plating solution cannot reach the leading-out end of the inner electrode 15 of the ceramic body 1, and the situation that the insulation resistance of the multilayer ceramic capacitor is decreased due to the plating solution permeating into the leading-out end of the inner electrode 15 of the ceramic body 1 can be avoided; the second insulating part 32 is not covered by the conductive layer 4 and the soldering layer 5, so that when the multilayer ceramic capacitor is soldered to the circuit board 6, the second insulating part 32 can be in direct contact with the pad 61 and is not coated with tin, and the soldering tin 62 can be prevented from entering the lower part, thereby reducing the mounting height of the multilayer ceramic capacitor and effectively saving space; meanwhile, the welding layer 5, the conductive layer 4, the terminal electrode 2 and the inner electrode 15 sequentially form a conductive path, so that the electrical parameters of the multilayer ceramic capacitor can be measured only by contacting the welding layer 5 with a test probe, and automatic electrical performance sorting can be realized.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (10)
1. A multilayer ceramic capacitor is characterized by comprising a ceramic body and two terminal electrodes arranged at two ends of the ceramic body respectively, wherein the terminal electrodes comprise a first electrode part covering the end face of the ceramic body and second electrode parts extending to four side faces of the ceramic body, the tail ends of the two second electrode parts are arranged oppositely, and a distance is reserved between the tail ends of the two second electrode parts;
the ceramic body comprises dielectric layers which are arranged in a stacked mode and inner electrodes which are arranged between two adjacent dielectric layers, each inner electrode comprises a first inner electrode and a second inner electrode which are arranged alternately, the first inner electrodes extend to the side face of the ceramic body to form first inner electrode leading-out ends, the first inner electrode leading-out ends are connected with a second electrode part in one terminal electrode, and the first inner electrodes are spaced from two end faces of the ceramic body; the second inner electrode extends to the side face of the ceramic body to form a second inner electrode leading-out end, the second inner electrode leading-out end is connected with a second electrode part in the other end electrode, and the second inner electrode is away from two end faces of the ceramic body;
the end electrode is covered with an insulating layer, the insulating layer comprises a first insulating part and a second insulating part, the first insulating part is arranged on the first electrode part, the second insulating part is covered on the second electrode part, the second insulating part extends to the side face of the ceramic body, a connecting through hole is formed in the middle of the first insulating part, a conducting layer covers the first insulating part, a connecting part matched with the connecting through hole is arranged in the middle of the conducting layer in a protruding mode, and a welding layer covers the conducting layer.
2. The multilayer ceramic capacitor according to claim 1, wherein the four sides of the ceramic body include two first sides disposed opposite to each other and two second sides disposed opposite to each other, the internal electrodes are T-shaped, the internal electrodes extend to the two first sides and are connected to the second electrode part, respectively, and the internal electrodes have distances from both end faces and both the second sides of the ceramic body.
3. The multilayer ceramic capacitor according to claim 1, wherein the second electrode portion of one of the terminal electrodes completely covers the first inner electrode lead; the second electrode part in the other terminal electrode completely covers the second inner electrode leading-out terminal.
4. The multilayer ceramic capacitor as claimed in claim 1, wherein a second electrode portion of one of the terminal electrodes partially covers the first inner electrode lead along a length direction of the ceramic body, and a second insulating portion provided on the one of the terminal electrodes completely covers the first inner electrode lead; the second electrode part of the other terminal electrode partially covers the second inner electrode leading-out terminal along the length direction of the ceramic body, and the second insulating part which is covered on the other terminal electrode completely covers the second inner electrode leading-out terminal.
5. The multilayer ceramic capacitor according to claim 1, wherein the shortest distance between the internal electrode terminals and the end face of the ceramic body adjacent thereto is denoted as d1; the d1 is 10-30% of the length of the ceramic body; recording the distance between the end face of the tail end of the second electrode part and the end face of the ceramic body close to the end face as d2; the d2 is 15-35% of the length of the ceramic body.
6. The multilayer ceramic capacitor of claim 1, wherein the solder layer is a single metal layer, and the solder layer is made of one of tin, gold, or silver; the thickness of the welding layer is 5-10 mu m.
7. The multilayer ceramic capacitor of claim 1, wherein said bonding layer comprises an inner metal layer and an outer metal layer, said inner metal layer overlying said conductive layer, said inner metal layer being made of nickel or nichrome; the outer metal layer is made of one of tin, gold or silver; the thickness of the inner metal layer is 2-5 μm; the thickness of the outer metal layer is 5-10 μm.
8. The multilayer ceramic capacitor according to claim 1, wherein the material of the insulating layer is ceramic or resin, and the thickness of the insulating layer is 5 μm to 20 μm.
9. The multilayer ceramic capacitor according to claim 1, wherein the conductive layer is made of one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy, or indium-gallium alloy, and the thickness of the conductive layer is 0.1 μm to 0.5 μm.
10. The method for producing a multilayer ceramic capacitor as claimed in any one of claims 1 to 9, comprising the steps of:
step 1, preparing a ceramic body;
step 2, respectively arranging end electrodes at two ends of the ceramic body;
step 3, arranging an insulating layer on the end electrode, and removing the central area of the first insulating part to form a connecting through hole so as to expose the end electrode in the area corresponding to the connecting through hole;
step 4, arranging a conductive layer on the first insulating part, and filling a connecting through hole in a connecting part on the conductive layer and connecting the connecting through hole with the terminal electrode;
and 5, arranging a welding layer on the conductive layer.
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| CN202211039601.4A CN115458331A (en) | 2022-08-29 | 2022-08-29 | Multilayer ceramic capacitor and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211039601.4A CN115458331A (en) | 2022-08-29 | 2022-08-29 | Multilayer ceramic capacitor and preparation method thereof |
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| CN115458331A true CN115458331A (en) | 2022-12-09 |
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