CN115148494A - Multilayer ceramic capacitor and preparation method thereof - Google Patents
Multilayer ceramic capacitor and preparation method thereof Download PDFInfo
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- CN115148494A CN115148494A CN202210895846.0A CN202210895846A CN115148494A CN 115148494 A CN115148494 A CN 115148494A CN 202210895846 A CN202210895846 A CN 202210895846A CN 115148494 A CN115148494 A CN 115148494A
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- 238000002360 preparation method Methods 0.000 title abstract description 6
- 239000000919 ceramic Substances 0.000 claims abstract description 160
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- 230000002093 peripheral effect Effects 0.000 claims abstract description 15
- 239000010410 layer Substances 0.000 claims description 163
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- 229910052802 copper Inorganic materials 0.000 claims description 31
- 239000010949 copper Substances 0.000 claims description 31
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 19
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 17
- 239000002002 slurry Substances 0.000 claims description 17
- 229910052718 tin Inorganic materials 0.000 claims description 17
- 229910052759 nickel Inorganic materials 0.000 claims description 13
- 238000009713 electroplating Methods 0.000 claims description 11
- 238000005245 sintering Methods 0.000 claims description 11
- 239000000758 substrate Substances 0.000 claims description 8
- 239000012528 membrane Substances 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
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- 239000003292 glue Substances 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 4
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- 238000005520 cutting process Methods 0.000 claims description 4
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- 239000011267 electrode slurry Substances 0.000 claims description 4
- 238000007639 printing Methods 0.000 claims description 4
- 238000004544 sputter deposition Methods 0.000 claims description 4
- 229910000570 Cupronickel Inorganic materials 0.000 claims description 3
- 229910000807 Ga alloy Inorganic materials 0.000 claims description 3
- 229910000756 V alloy Inorganic materials 0.000 claims description 3
- 229910001080 W alloy Inorganic materials 0.000 claims description 3
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- 238000007598 dipping method Methods 0.000 claims description 3
- 238000010030 laminating Methods 0.000 claims description 3
- HBVFXTAPOLSOPB-UHFFFAOYSA-N nickel vanadium Chemical compound [V].[Ni] HBVFXTAPOLSOPB-UHFFFAOYSA-N 0.000 claims description 3
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 239000002356 single layer Substances 0.000 claims description 3
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 claims description 3
- 238000005253 cladding Methods 0.000 claims 1
- 238000007747 plating Methods 0.000 abstract description 35
- 238000009413 insulation Methods 0.000 abstract description 10
- 239000003990 capacitor Substances 0.000 abstract description 3
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 230000035515 penetration Effects 0.000 description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000012298 atmosphere Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910000679 solder Inorganic materials 0.000 description 4
- 238000005476 soldering Methods 0.000 description 4
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- 229910052757 nitrogen Inorganic materials 0.000 description 3
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- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 2
- 229910002113 barium titanate Inorganic materials 0.000 description 2
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- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
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- 239000003960 organic solvent Substances 0.000 description 1
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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
- H01G4/005—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
-
- 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
- H01G4/008—Selection of materials
-
- 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
-
- 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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (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 which are respectively arranged on two end surfaces of the ceramic body, the terminal electrodes extend to the peripheral side surface of the ceramic body, the tail ends of the two terminal electrodes are oppositely arranged, a distance is reserved between the tail ends of the two terminal electrodes, the terminal electrodes are covered with an insulating layer, a conducting layer is coated on the insulating layer, the conducting layer covers the insulating layer and extends to the terminal electrodes, and the end parts of the terminal electrodes are exposed out of the conducting layer; the invention can perform automatic electric performance sorting, and ensures that the connecting area of the multilayer ceramic capacitor and the circuit board is small and the distance between two welding points is small, thereby effectively inhibiting the piezoelectric vibration of the multilayer ceramic capacitor from being transmitted to the circuit board, reducing the squealing noise of the circuit board, and preventing the plating solution from reaching the inner electrode due to long plating solution permeation path without causing the reduction of insulation resistance.
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, barium titanate-based ceramics are widely used as dielectric materials for high-capacitance multilayer ceramic capacitors, but since barium titanate-based ceramics have inverse piezoelectric effects, there is a problem that when an alternating voltage is applied to the multilayer ceramic capacitor, the multilayer ceramic capacitor generates stretching vibration and the vibration is transmitted to the wiring board through solder joints, causing the wiring board to vibrate to generate a buzzer sound. The higher the capacitance of the multilayer ceramic capacitor, the more severe the wiring board squealing.
Disclosure of Invention
The invention aims to provide a multilayer ceramic capacitor which can carry out automatic electric performance sorting, has a long plating solution permeation path, can prevent the plating solution from reaching an inner electrode without causing insulation resistance reduction, effectively inhibits piezoelectric vibration from being transmitted to a circuit board and reduces circuit board squealing noise and a preparation method thereof.
In order to achieve the above object, in one aspect, the present invention provides a multilayer ceramic capacitor, including a ceramic body and two terminal electrodes respectively disposed on two end surfaces of the ceramic body, where the terminal electrodes extend to a peripheral side surface of the ceramic body, ends of the two terminal electrodes are disposed opposite to each other with a distance therebetween, the terminal electrodes are covered with an insulating layer, the insulating layer is covered with a conductive layer, the conductive layer covers the insulating layer and extends to the terminal electrodes, and ends of the terminal electrodes are exposed out of the conductive layer.
As a preferable aspect of the present invention, the terminal electrode includes a connection electrode and a welding electrode, the connection electrode is disposed on an end surface of the ceramic body in a covering manner and extends to an outer peripheral side surface of the ceramic body, the welding electrode is disposed around the outer peripheral side surface and is connected to an end surface of a terminal of the connection electrode, the connection electrode is a single-layer electrode, and the welding electrode is a composite-layer electrode; the insulating layer covers the connecting electrode, and the conductive layer completely covers the insulating layer and extends to the welding electrode.
In a preferred embodiment of the present invention, the connection electrode is a copper electrode; the welding electrode comprises a bottom electrode, a middle electrode and a top electrode which are sequentially arranged from inside to outside, the bottom electrode is a copper electrode layer, and the middle electrode is a nickel electrode layer; the top electrode is a tin electrode layer; the conducting layer is made of any one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy and indium-gallium alloy.
In a preferred embodiment of the present invention, a distance between a distal end surface of the welding electrode and an end surface of the ceramic body adjacent thereto is represented as d1; recording a distance between the end face of the terminal of the connection electrode and the end face of the ceramic body close to the end face as d2, wherein the distance between the end face of the terminal of the connection electrode and the end face of the ceramic body close to the end face is equal to the distance between the end face of the terminal of the insulating layer and the end face of the ceramic body close to the end face; recording the distance between the end face of the conductive layer and the end face of the ceramic body close to the end face as d3; d1 is greater than d3, and d3 is greater than d2.
In a preferred embodiment of the present invention, d1 is 12 to 35% of the length of the ceramic body; the d2 is 2-22% of the length of the ceramic body; the d3 is 5-25% of the length of the ceramic body.
As a preferable scheme of the invention, the thickness of the connecting electrode and the bottom layer electrode is 5-60 μm; the thickness of the insulating layer is 5-20 μm; the thickness of the conductive layer is preferably 0.1 to 0.5 μm.
As a preferable aspect of the present invention, the ceramic body includes dielectric layers disposed in a stacked manner and internal electrodes disposed between two adjacent dielectric layers, the internal electrodes include first internal electrodes and second internal electrodes, one end of each of the first internal electrodes is connected to one of the terminal electrodes, a distance is provided between a terminal of each of the first internal electrodes and the other terminal electrode, one end of each of the second internal electrodes is connected to the other terminal electrode, a distance is provided between a terminal of each of the second internal electrodes and the terminal electrode connected to the first internal electrode, and the first internal electrodes and the second internal electrodes are alternately disposed.
In addition, another aspect of the present invention also provides a method for manufacturing a multilayer ceramic capacitor, comprising the steps of:
step 1, preparing a ceramic body;
and 5, preparing a conductive layer on the insulating layer by a sputtering method, wherein the conductive layer completely covers the insulating layer and extends to the top electrode of the welding electrode.
In a preferred embodiment of the present invention, the connection electrode is a copper electrode, the bottom electrode is a copper electrode layer, and the middle electrode is a nickel electrode layer; the top electrode is a tin electrode layer.
As a preferred embodiment of the present invention, the step 1 comprises the following specific steps:
step 1.1, preparing a ceramic diaphragm by using ceramic slurry as a raw material;
step 1.2, printing inner electrode slurry on the ceramic diaphragm to form an inner electrode pattern, and drying the inner electrode slurry to obtain the ceramic diaphragm with the inner electrode;
step 1.3, laminating a plurality of ceramic diaphragms with internal electrodes 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;
step 1.4, compressing and cutting the ceramic substrate to obtain a plurality of ceramic plates;
and step 1.5, removing glue from the ceramic wafer and sintering to obtain the ceramic body.
Compared with the prior art, the multilayer ceramic capacitor and the preparation method thereof have the beneficial effects that:
according to the invention, the insulating layer is arranged to prevent the penetration of the plating solution during the subsequent electroplating operation, the plating solution can only enter along the end part of the terminal electrode which is not covered by the insulating layer, and the penetration direction of the plating solution can only enter along the terminal electrode, so that the penetration surface is narrow and the penetration path is long, and the plating solution cannot reach the inner electrode exposed out of the ceramic body, so that the situation that the insulation resistance of the multilayer ceramic capacitor is reduced due to the penetration of the plating solution into the ceramic body can be avoided, and the conductive layer is arranged on the surface of the insulating layer and can conduct with the terminal electrode to form reliable electric connection with the inner electrode in the ceramic body, thereby facilitating the automatic electric performance sorting of the multilayer ceramic capacitor; in addition, the multilayer ceramic capacitor is welded with the circuit board through the end part of the terminal electrode exposed out of the conducting layer, so that the connecting area of the multilayer ceramic capacitor and the circuit board is small, the distance between two welding points is small, the piezoelectric vibration of the multilayer ceramic capacitor can be effectively inhibited from being transmitted to the circuit board, and the circuit board squealing noise is reduced.
Drawings
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 provided by the present invention;
FIG. 4 is a schematic view of a multilayer ceramic capacitor according to the present invention;
FIG. 5 is a schematic view of a multilayer ceramic capacitor according to the present invention soldered to a wiring board;
FIG. 6 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 a dielectric layer; 12 is an inner electrode; 13 is the end face of the ceramic body; 14 is the side of the ceramic body; 2 is a terminal electrode; 21 is a connecting electrode; 22 is a welding electrode; 3 is an insulating layer; 4 is a conductive layer; 7 is a circuit board; 71 is soldering tin; and 72 is a bonding pad.
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 5, 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 on two end surfaces of the ceramic body 1, wherein the terminal electrodes 2 extend to the outer peripheral side surface of the ceramic body 1, the ends of the two terminal electrodes 2 are disposed opposite to each other with a distance therebetween, the terminal electrodes 2 are covered with an insulating layer 3, the insulating layer 3 is covered with a conductive layer 4, the conductive layer 4 covers the insulating layer 3 and extends to the terminal electrodes 2, and the end portions of the terminal electrodes 2 are exposed out of the conductive layer 4. Preferably, the ceramic body 1 has a rectangular parallelepiped structure, and the terminal electrodes 2 extend to four sides of the ceramic body 1.
Illustratively, the terminal electrode 2 includes a connection electrode 21 and a welding electrode 22, the connection electrode 21 is disposed on the end surface 13 of the ceramic body 1 in a covering manner and extends to the outer peripheral side surface of the ceramic body 1, the welding electrode 22 is disposed on the outer peripheral side surface in a surrounding manner and is connected to the terminal end surface of the connection electrode 21, the connection electrode 21 is a single-layer electrode, and the welding electrode 22 is a composite-layer electrode; the insulating layer 3 covers the connecting electrode 21, and the conductive layer 4 completely covers the insulating layer 3 and extends to the welding electrode 22; the conductive layer 4 completely covers the insulating layer 3 and forms a conductive path with the welding electrode 22, the connection electrode 21 and the inner electrode 12 of the ceramic body 1, so that the electrical parameters of the multilayer ceramic capacitor can be measured only by contacting the conductive layer 4 on the multilayer ceramic capacitor with a test probe, thereby realizing automatic electrical performance sorting. Specifically, the connection electrode 21 is a copper electrode; the welding electrode 22 comprises a bottom electrode, a middle electrode and a top electrode which are arranged from inside to outside in sequence, the bottom electrode is a copper electrode layer, the middle electrode is a nickel electrode layer, and the thickness of the nickel electrode layer is preferably 2-5 micrometers; the top electrode is a tin electrode layer, and the thickness of the tin electrode layer is preferably 5-10 μm; the nickel electrode layer can protect the copper electrode layer and prevent the leaching phenomenon during welding; the tin electrode layer on the top layer can play a role in soldering. Since the connection electrode 21 in the terminal electrode 2 is completely covered with the insulating layer 3, the plating solution cannot directly penetrate into the connection electrode 21, but the plating solution may penetrate into the welding electrode 22 and may further indirectly penetrate into the connection electrode 21 adjacent to the welding electrode 22, but unlike the multilayer ceramic capacitor of the related art, when the plating solution penetrates, the penetration direction of the multilayer ceramic capacitor of the related art is substantially perpendicular to the copper layer surface, the penetration surface is large, and the penetration path is short, so that the plating solution easily penetrates into the ceramic body 1 to cause a decrease in insulation resistance, whereas the connection electrode 21 of the multilayer ceramic capacitor of the present embodiment extends a distance on four sides of the ceramic body 1, the penetration direction of the plating solution is along the copper layer surface, the penetration surface is narrow, and the penetration source is located at the end surface of the connection electrode 21, the penetration path is long, so that the plating solution cannot reach the internal electrodes 12 exposed on both end surfaces of the ceramic body 1, so that the decrease in insulation resistance is not caused. Of course, in other embodiments, the conductive layer 4 may partially cover the insulating layer 3, and the conductive layer 4 extends onto the welding electrode 22, so as to ensure that the conductive layer 4 realizes a conductive path through the terminal electrode 2 and the inner electrode 12, thereby enabling automatic electric performance sorting of the multilayer ceramic capacitor.
Illustratively, the material of the conductive layer 4 is any one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy and indium-gallium alloy, and tin is easily added by avoiding tin, gold, silver and the like. The thickness of the conductive layer 4 is preferably 0.1 μm to 0.5 μm, and if the thickness of the conductive layer 4 is too small, the conductivity may be deteriorated, and if the thickness of the conductive layer 4 is too large, the tin-coating of the welding electrode 22 may be hindered. The outermost layer of the welding electrode 22 is a tin layer which functions as a soldering aid and facilitates tin application during welding, and the material of the conductive layer 4 is a metal or alloy having relatively low solderability and the conductive layer 4 is not tin-applied during welding, so that the connection area between the multilayer ceramic capacitor and the wiring board 7 is significantly reduced by tin application only to the welding electrode 22 as compared with the conventional technique, and the transmission of piezoelectric vibration of the multilayer ceramic capacitor to the wiring board 7 and the squeaking of the wiring board 7 can be suppressed. If the extending distance of the terminal electrode 2 and the insulating layer 3 on the four sides of the ceramic body 1 is increased, the two welding electrodes 22 can be made to approach each other, and the distance between the two welding points is reduced, so that the vibration of the circuit board 7 can be further reduced, and the squealing noise can be reduced.
And figure 1 is the sketch map of welding present multilayer ceramic capacitor to circuit board 7 ', four sides of present multilayer ceramic capacitor all can regard as the welding face, because whole terminal electrode 2' is the tin layer outward, thereby the solder can climb on multilayer ceramic capacitor's both ends terminal surface during soldering tin and make multilayer ceramic capacitor and circuit board 7's area of connection increase, and the distance between the solder joint at both ends is great, the piezoelectricity vibration that multilayer ceramic capacitor produced like this can transmit circuit board 7 'in a large number, make the vibration and the noise aggravation of circuit board 7'.
Illustratively, the distance between the end face of the tip of the welding electrode 22 and the end face 13 of the ceramic body 1 adjacent thereto is denoted as d1; let d2 be the distance between the end face of the end of the connection electrode 21 and the end face 13 of the ceramic body 1 adjacent thereto, and the distance between the end face of the end of the connection electrode 21 and the end face 13 of the ceramic body 1 adjacent thereto is equal to the distance between the end face of the end of the insulating layer 3 and the end face 13 of the ceramic body 1 adjacent thereto; the distance between the end face of the conductive layer 4 and the end face 13 of the ceramic body 1 adjacent thereto is denoted as d3; d1 is greater than d3, and d3 is greater than d2. Specifically, d1 is 12% to 35% of the length of the ceramic body 1, when d1 is too small, it is inconvenient to weld a multilayer ceramic capacitor on the circuit board 7, and when d1 is too large, the two terminal electrodes 2 are easily short-circuited; d2 is 2-22% of the length of the ceramic body 1, when d2 is too small, the effect of preventing the plating solution from permeating is insufficient, and when d2 is too large, the multilayer ceramic capacitor is not convenient to weld on the circuit board 7; the d3 is 5 to 25% of the length of the ceramic body 1, and when d3 is too small, it is inconvenient to form a reliable electrical connection between the conductive layer 4 and the welding electrode 22, and when d3 is too large, the conductive layer 4 covers the welding electrode 22 too much, thereby making it inconvenient to weld the multilayer ceramic capacitor on the wiring board 7.
Illustratively, the thickness of the connecting electrode 21 and the bottom electrode is preferably 5 μm to 60 μm, when the thickness of the connecting electrode 21 and the bottom electrode is too small, the continuity of the copper layer is not good for conducting electricity, and when the thickness of the connecting electrode 21 and the bottom electrode is too large, the volume of the multilayer ceramic capacitor is not good for reducing; the thickness of the insulating layer 3 is 5-20 μm, when the thickness of the insulating layer 3 is too small, the effect of preventing the plating solution from permeating is insufficient, and when the thickness of the insulating layer 3 is too large, the reduction of the volume of the multilayer ceramic capacitor is not facilitated; the insulating layer 3 is preferably a ceramic insulating layer 3 or a resin insulating layer 3.
Specifically, the ceramic body 1 includes dielectric layers 11 stacked and inner electrodes 12 disposed between two adjacent dielectric layers 11, where the inner electrodes 12 include first inner electrodes 12 and second inner electrodes 12, one end of each first inner electrode 12 is connected to one of the terminal electrodes 2, a distance is provided between a terminal of each first inner electrode 12 and the other terminal electrode 2, one end of each second inner electrode 12 is connected to the other terminal electrode 2, a distance is provided between a terminal of each second inner electrode 12 and the terminal electrode 2 connected to the first inner electrode 12, and the first inner electrodes 12 and the second inner electrodes 12 are alternately disposed.
As shown in fig. 3 to 5, the present invention also provides a method for manufacturing a multilayer ceramic capacitor, which comprises the steps of:
step 1, preparing a ceramic body 1;
and 5, preparing a conductive layer 4 on the insulating layer 3 by a sputtering method, wherein the conductive layer 4 completely covers the insulating layer 3 and extends to the top electrode of the welding electrode 22.
Wherein, the distance between the end face of the end of the welding electrode 22 and the end face 13 of the ceramic body 1 adjacent thereto is denoted as d1; let d2 be the distance between the end face of the end of the connection electrode 21 and the end face 13 of the ceramic body 1 adjacent thereto, and the distance between the end face of the end of the connection electrode 21 and the end face 13 of the ceramic body 1 adjacent thereto is equal to the distance between the end face of the end of the insulating layer 3 and the end face 13 of the ceramic body 1 adjacent thereto; the distance between the end face of the conductive layer 4 and the end face 13 of the ceramic body 1 adjacent thereto is denoted as d3; d1 is greater than d3, and d3 is greater than d2. Specifically, d1 is 12% to 35% of the length of the ceramic body 1, when d1 is too small, it is inconvenient to weld the multilayer ceramic capacitor on the circuit board 7, and when d1 is too large, the two terminal electrodes 2 are easily short-circuited; d2 is 2-22% of the length of the ceramic body 1, when d2 is too small, the effect of preventing the plating solution from permeating is insufficient, and when d2 is too large, the multilayer ceramic capacitor is inconvenient to weld on the circuit board 7; the d3 is 5 to 25% of the length of the ceramic body 1, and when d3 is too small, it is inconvenient for the conductive layer 4 to form a reliable electrical connection with the bonding electrode 22, and when d3 is too large, the conductive layer 4 covers the bonding electrode 22 too much, thereby making it inconvenient to bond the multilayer ceramic capacitor on the wiring board 7.
Further, the step 1 comprises the following specific steps:
step 1.1, preparing a ceramic diaphragm by using the ceramic slurry as a raw material, wherein the ceramic diaphragm is the dielectric layer 11; 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;
step 1.2, printing inner electrode 12 slurry on the ceramic diaphragm to form an inner electrode 12 pattern, and drying the inner electrode 12 slurry to obtain the ceramic diaphragm with the inner electrode 12; the method comprises the following specific steps: printing the inner electrode 12 slurry on the ceramic membrane by adopting a screen printing or gravure printing method to form an inner electrode 12 pattern on one side surface of the ceramic membrane, and drying the inner electrode 12 slurry to obtain the ceramic membrane with the inner electrode 12; wherein, the inner electrode 12 slurry adopts nickel slurry;
step 1.3, laminating a plurality of ceramic diaphragms with inner electrodes 12 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 12 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 comprises the following specific steps: and (3) compacting the ceramic substrate by adopting 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. The ceramic chip comprises two end faces which are oppositely arranged, one group of internal electrodes 12 (first internal electrodes) are exposed out of one end face of the ceramic chip, and the other group of internal electrodes 12 (second internal electrodes) are exposed out of the other end face of the ceramic chip;
step 1.5, removing glue from the ceramic wafer and sintering to obtain a ceramic body 1; the method specifically comprises the following steps: firstly, carrying out glue discharging operation, wherein the glue discharging operation is to heat the ceramic wafer to 250-350 ℃ in the air and keep the temperature for 0.5-3 hours to discharge the adhesive contained in the ceramic wafer, or to heat the ceramic wafer to 350-600 ℃ in the nitrogen and keep the temperature 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.
As shown in fig. 6, the penetration path of the plating solution in the plating of the multilayer ceramic capacitor of the present embodiment is indicated by an arrow in fig. 6, and the dotted line frame indicates that the penetration of the plating solution to the position causes a decrease in insulation resistance, and the penetration path of the plating solution is long, and the plating solution cannot reach the internal electrodes 12 exposed at the end faces of the ceramic body 1, so that the decrease in insulation resistance 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 conclusion, the insulating layer 3 is arranged to prevent the plating solution from permeating during the subsequent electroplating operation, the plating solution can only enter along the end part of the terminal electrode 2 which is not covered by the insulating layer 3, the plating solution can only enter along the terminal electrode 2 in the permeation direction, so that the permeation surface is narrow, the permeation path is long, and the plating solution cannot reach the inner electrode 12 exposed out of the ceramic body 1, thereby avoiding the situation that the insulation resistance of the multilayer ceramic capacitor is reduced due to the fact that the plating solution permeates into the ceramic body 1, and the conducting layer 4 is arranged on the surface of the insulating layer 3, can conduct electricity with the terminal electrode 2 and further can form reliable electric connection with the inner electrode 12 in the ceramic body 1, and is convenient for automatic electric performance sorting of the multilayer ceramic capacitor; in addition, the multilayer ceramic capacitor is soldered to the wiring board 7 by the end of the terminal electrode 2 exposed from the conductive layer 4, so that the connection area between the multilayer ceramic capacitor and the wiring board 7 is small and the distance between two solder points is small, thereby effectively suppressing the transmission of the piezoelectric vibration of the multilayer ceramic capacitor to the wiring board 7 and reducing the squeaking noise of the wiring board 7.
In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, 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. The utility model provides a multilayer ceramic capacitor, its characterized in that, include the ceramic body and two set up respectively in termination electrode on the both ends face of ceramic body, termination electrode extends to on the periphery side of ceramic body, and two termination electrode's end sets up relatively and has the distance between the two, termination electrode covers and is equipped with the insulating layer, the cladding has the conducting layer on the insulating layer, the conducting layer covers the insulating layer just extends to on the termination electrode, termination electrode's tip expose in the conducting layer.
2. The multilayer ceramic capacitor according to claim 1, wherein the terminal electrode comprises a connection electrode disposed on an end face of the ceramic body in a covering manner and extending to an outer peripheral side face of the ceramic body, and a welding electrode disposed on the outer peripheral side face in a surrounding manner and connected to a distal end face of the connection electrode, the connection electrode is a single-layer electrode, and the welding electrode is a composite-layer electrode; the insulating layer covers the connecting electrode, and the conductive layer completely covers the insulating layer and extends to the welding electrode.
3. The multilayer ceramic capacitor according to claim 2, wherein the connection electrode is a copper electrode; the welding electrode comprises a bottom electrode, a middle electrode and a top electrode which are arranged from inside to outside in sequence, the bottom electrode is a copper electrode layer, and the middle electrode is a nickel electrode layer; the top electrode is a tin electrode layer; the conducting layer is made of any one of copper, nickel, copper-nickel alloy, nickel-chromium alloy, nickel-vanadium alloy, titanium-tungsten alloy and indium-gallium alloy.
4. The multilayer ceramic capacitor according to claim 2, wherein the distance between the end face of the terminal of the welding electrode and the end face of the ceramic body adjacent thereto is denoted as d1; recording a distance between the end face of the terminal of the connection electrode and the end face of the ceramic body close to the end face as d2, wherein the distance between the end face of the terminal of the connection electrode and the end face of the ceramic body close to the end face is equal to the distance between the end face of the terminal of the insulating layer and the end face of the ceramic body close to the end face; recording the distance between the end face of the tail end of the conductive layer and the end face of the ceramic body close to the conductive layer as d3; d1 is greater than d3, and d3 is greater than d2.
5. The multilayer ceramic capacitor of claim 4, wherein d1 is 12% to 35% of the length of the ceramic body; the d2 is 2-22% of the length of the ceramic body; the d3 is 5-25% of the length of the ceramic body.
6. The multilayer ceramic capacitor according to claim 3, wherein the connecting electrode and the bottom layer electrode each have a thickness of 5 μm to 60 μm; the thickness of the insulating layer is 5-20 μm; the thickness of the conductive layer is preferably 0.1 to 0.5 μm.
7. The multilayer ceramic capacitor according to any one of claims 1 to 6, wherein the ceramic body comprises dielectric layers arranged in layers and internal electrodes arranged between two adjacent dielectric layers, the internal electrodes comprise first internal electrodes and second internal electrodes, one end of the first internal electrode is connected to one of the terminal electrodes, a distal end of the first internal electrode has a distance from the other of the terminal electrodes, one end of the second internal electrode is connected to the other of the terminal electrodes, a distal end of the second internal electrode has a distance from the terminal electrode connected to the first internal electrode, and the first internal electrodes and the second internal electrodes are alternately arranged.
8. A method for manufacturing a multilayer ceramic capacitor, comprising the steps of:
step 1, preparing a ceramic body;
step 2, arranging end electrodes at two ends of the ceramic body: respectively dipping metal slurry at two ends of the ceramic body and heating and sintering the metal slurry to enable the metal slurry to form a connecting electrode in the terminal electrodes attached to the two ends of the ceramic body and a bottom electrode of a welding electrode in the terminal electrodes; the end electrode comprises a connecting electrode and a welding electrode, the connecting electrode is arranged on the end face of the ceramic body in a covering mode and extends to the peripheral side face of the ceramic body, and the welding electrode is arranged on the peripheral side face in a surrounding mode and is connected with the tail end face of the connecting electrode;
step 3, preparing an insulating layer on the connecting electrode, wherein the distance between the end face of the tail end of the connecting electrode and the end face of the ceramic body close to the connecting electrode is equal to the distance between the end face of the tail end of the insulating layer and the end face of the ceramic body close to the connecting electrode;
step 4, covering a bottom electrode by an electroplating method to form a middle electrode, and then covering the middle electrode by the electroplating method to form a top electrode, wherein the welding electrode comprises the bottom electrode, the middle electrode and the top electrode which are sequentially arranged from inside to outside;
and 5, preparing a conductive layer on the insulating layer by a sputtering method, wherein the conductive layer completely covers the insulating layer and extends to the top electrode of the welding electrode.
9. The method of manufacturing a multilayer ceramic capacitor as claimed in claim 8, wherein the connection electrode is a copper electrode, the bottom electrode is a copper electrode layer, and the middle electrode is a nickel electrode layer; the top electrode is a tin electrode layer.
10. The method for producing a multilayer ceramic capacitor as claimed in claim 8, wherein the step 1 comprises the following specific steps:
step 1.1, preparing a ceramic diaphragm by using ceramic slurry as a raw material;
step 1.2, printing inner electrode slurry on the ceramic diaphragm to form an inner electrode pattern, and drying the inner electrode slurry to obtain the ceramic diaphragm with the inner electrode;
step 1.3, laminating a plurality of ceramic diaphragms with internal electrodes 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;
step 1.4, compressing and cutting the ceramic substrate to obtain a plurality of ceramic plates;
and step 1.5, removing glue from the ceramic wafer and sintering to obtain the ceramic body.
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| CN202210895846.0A CN115148494A (en) | 2022-07-27 | 2022-07-27 | Multilayer ceramic capacitor and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115312323A (en) * | 2022-07-04 | 2022-11-08 | 武汉神动汽车电子电器股份有限公司 | Anti-seepage gage pressure ceramic capacitor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115312323A (en) * | 2022-07-04 | 2022-11-08 | 武汉神动汽车电子电器股份有限公司 | Anti-seepage gage pressure ceramic capacitor |
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