Preparation method of laminated ceramic capacitor for wireless charging
阅读说明：本技术 一种无线充电用积层式陶瓷电容器的制备方法 (Preparation method of laminated ceramic capacitor for wireless charging ) 是由 李吉晓 何建成 李岩 于 2019-09-17 设计创作，主要内容包括：本发明专利涉及电子材料及元器件技术领域,旨在提供一种无线充电用积层式陶瓷电容器的制备方法,其技术方案要点是：包括以下步骤：S1、陶瓷浆料制备；S2、陶瓷生片的制备；S3、印刷叠层：以矩形陶瓷生片一侧长边为印刷基准边,在矩形陶瓷生片上表面印刷出矩形内电极区,矩形内电极区与矩形陶瓷生片边沿之间形成非电极区,从而在矩形陶瓷生片上表面形成内电极,再以内电极交错的方式将后一片矩形陶瓷生片叠于前一片矩形陶瓷生片印刷有内电极的表面,循环层叠至要求的层数；S4、叠层静压；S5、切割；S6、排胶；S7、烧结；S8、端头处理,本发明具有加工产品良率高,所加工的电容器单体电容量高、电流传输发热量小的优点。(The invention relates to the technical field of electronic materials and components, and aims to provide a preparation method of a laminated ceramic capacitor for wireless charging, which has the technical scheme that the key points are as follows: the method comprises the following steps: s1, preparing ceramic slurry; s2, preparing a ceramic green sheet; s3, printing the laminate: printing a rectangular inner electrode area on the upper surface of the rectangular ceramic green sheet by taking the long side of one side of the rectangular ceramic green sheet as a printing reference side, and forming a non-electrode area between the rectangular inner electrode area and the edge of the rectangular ceramic green sheet, so as to form an inner electrode on the upper surface of the rectangular ceramic green sheet, stacking the next rectangular ceramic green sheet on the surface of the previous rectangular ceramic green sheet printed with the inner electrode in an inner electrode staggered mode, and circularly stacking to the required number of layers; s4, laminating static pressure; s5, cutting; s6, removing glue; s7, sintering; s8, end processing, the invention has the advantages of high yield of processed products, high capacitance of the processed capacitor monomer and small heat productivity of current transmission.)
1. A preparation method of a laminated ceramic capacitor for wireless charging is characterized by comprising the following steps:
s1, preparing ceramic slurry: adding ceramic powder, adhesive and solvent into a ball mill according to a certain proportion, and ball-milling to prepare dielectric ceramic slurry;
s2, preparation of ceramic green sheet: casting the ceramic slurry prepared in the step S1 on the surface of the base band film through a casting opening of a casting machine, and drying the ceramic slurry layer through a drying box of the casting machine, wherein a single-layer ceramic green sheet is formed on the base band film after the ceramic slurry is dried;
s3, printing the laminate: cutting, printing and laminating the ceramic green sheet prepared in the step S2;
the printing step is to uniformly print electrode slurry on the upper surface of the cut rectangular ceramic green sheet (2) in a screen printing mode, and specifically, the method is to print a rectangular inner electrode area (21) on the upper surface of the rectangular ceramic green sheet (2) by taking the long side of one side of the rectangular ceramic green sheet (2) as a printing reference side, and a non-electrode area (22) is formed between the rectangular inner electrode area (21) and the edge of the rectangular ceramic green sheet (2), so that an inner electrode is formed on the upper surface of the rectangular ceramic green sheet (2);
the lamination mode is that a rear cut rectangular ceramic green sheet (2) is laminated on the upper surface of a front rectangular ceramic green sheet (2) printed with the inner electrode in an inner electrode staggered mode through a capacitance laminator, and the layers are circularly laminated until the corresponding layers are laminated and reach the corresponding specification;
when laminating, 3 layers of rectangular ceramic blank green sheets (1) are respectively left at the bottom and the top to be used as upper and lower end covers, and the rectangular ceramic blank green sheets (1) are not printed with internal electrodes;
s4, stack static pressure: carrying out isostatic pressing on the multilayer ceramic green sheet laminated in the step S3 on a static press;
s5, cutting: cutting the laminated multilayer ceramic green sheet obtained in the step S4 to form a plurality of chip green bodies with specific dimensional accuracy and good consistency;
s6, removing glue: putting the chip green body prepared in the step S5 into a bell-type furnace for drying and discharging glue, and drying and discharging redundant glue solution;
s7, sintering: placing the chip subjected to the glue discharging in the step S6 into a mesh belt type tunnel resistance furnace for sintering, and forming a capacitor matrix;
s8, end processing: and (4) performing end processing on the capacitor base body sintered in the step S7 to form the laminated ceramic capacitor.
2. The method of claim 1, wherein the ceramic powder in the step of S1 is a multi-component dielectric ceramic powder of MgTiO3-CaTiO3-TiO2-Nb2O5-Nd2O3-Bi2O 3.
3. The method for producing a multilayer ceramic capacitor for wireless charging according to claim 1, wherein: and in the step S4, the static pressure is 34-42 MPa, the static pressure time is 20-30 min, and the temperature is 50-60 ℃.
4. The method for producing a multilayer ceramic capacitor for wireless charging according to claim 1, wherein: and in the step S6, the glue discharging temperature is 185-350 ℃, and the glue discharging time is 50-60 h.
5. The method for producing a multilayer ceramic capacitor for wireless charging according to claim 1, wherein: in the step S7, the sintering temperature is 1050-1400 ℃, and the sintering time is 1-4 h.
6. The method for producing a multilayer ceramic capacitor for wireless charging according to claim 5, wherein: the sintering comprises a temperature rising section, a heat preservation section, a temperature reduction section and a tempering section, and the sintering atmosphere is air.
7. The method as claimed in claim 1, wherein the step S8, the step of end processing, comprises the steps of:
s801, placing the sintered capacitor matrix into a chamfering machine for chamfering and grinding, and exposing the inner electrodes at two ends of the capacitor matrix through chamfering and grinding;
s802, bonding silver paste outside the inner electrode exposed at the end part, and roasting the capacitor matrix bonded with the silver paste to form a substrate electrode;
and S803, forming an external electrode on the outer surface of the substrate electrode in a lead-free electroplating mode, and finally obtaining the finished product of the laminated ceramic capacitor.
8. The method as claimed in claim 7, wherein the chamfer grinding material in step S801 is silicon carbide or calcite beads with a diameter of 10 μm to 1 mm.
9. The method for producing a multilayer ceramic capacitor for wireless charging according to claim 7, wherein: in the step S802, the roasting temperature is 800 ℃, and the roasting time lasts for 15 min.
Technical Field
The invention relates to the technical field of electronic materials and components, in particular to a preparation method of a laminated ceramic capacitor for wireless charging.
Background
Multilayer Ceramic capacitors (MLCC) are also called monolithic capacitors, which are formed by stacking Ceramic dielectric films with printed electrodes (inner electrodes) in a staggered manner, sintering the stacked Ceramic dielectric films at a high temperature at one time to form a Ceramic chip, and sealing metal layers (outer electrodes) at two ends of the chip to form a structural body similar to a monolith. The laminated ceramic capacitor has the advantages of small volume, large specific volume, high reliability, long service life and suitability for surface mounting, and has the characteristic of 'direct connection and direct connection' of the capacitor. At present, laminated ceramic capacitors have been widely used in the fields of electronic information, computer, automatic control, and communication, and have a trend toward ultra-thin films and high lamination.
The NPO section material capacitor is adopted in the field of wireless charging, 4 1206 packaged 0.1uf/NPO are usually used in a single wireless charger, and in the charging process, as shown in fig. 3, a rectangular inner electrode area on a capacitor ceramic green sheet is printed along the length direction of the ceramic green sheet, so that current generally transmits current along the longitudinal direction, the resistance in the electrode is large, 1-2 amperes of current continuously passes through the inside of the capacitor, the capacitor is heated, and the continuous heat can cause the temperature of the charger to rise so as to have certain risk. Therefore, the developed laminated ceramic capacitor which has high monomer capacitance, small heat productivity in current transmission and easy processing has wide industrial application prospect and great social and economic benefits.
SUMMARY OF THE PATENT FOR INVENTION
The invention aims to provide a preparation method of a laminated ceramic capacitor for wireless charging, which has the advantages of good processing technology stability, high product yield, high capacitance of a processed capacitor monomer and small heat generation of current transmission.
The technical purpose of the invention is realized by the following technical scheme:
a preparation method of a laminated ceramic capacitor for wireless charging comprises the following steps:
s1, preparing ceramic slurry: adding ceramic powder, adhesive and solvent into a ball mill according to a certain proportion, and ball-milling to prepare dielectric ceramic slurry;
s2, preparation of ceramic green sheet: casting the ceramic slurry prepared in the step S1 on the surface of the base band film through a casting opening of a casting machine, and drying the ceramic slurry layer through a drying box of the casting machine, wherein a single-layer ceramic green sheet is formed on the base band film after the ceramic slurry is dried;
s3, printing the laminate: cutting, printing and laminating the ceramic green sheet prepared in the step S2;
the printing step is to uniformly print electrode slurry on the upper surface of the cut rectangular ceramic green sheet in a screen printing mode, and the specific method is to print a rectangular inner electrode area on the upper surface of the rectangular ceramic green sheet by taking the long edge at one side of the rectangular ceramic green sheet as a printing reference edge, and form a non-electrode area between the rectangular inner electrode area and the edge of the rectangular ceramic green sheet, so that an inner electrode is formed on the upper surface of the rectangular ceramic green sheet;
the lamination mode is that a rear cut rectangular ceramic green sheet is laminated on the upper surface of a front rectangular ceramic green sheet printed with the inner electrode in an inner electrode staggered mode through a capacitance laminator, and the lamination is carried out in a circulating mode until the corresponding number of layers is laminated and the corresponding specification is reached;
3 layers of rectangular ceramic blank green sheets are left at the bottom and the top respectively to be used as upper and lower end covers during lamination, and the rectangular ceramic blank green sheets are not printed with internal electrodes;
s4, stack static pressure: carrying out isostatic pressing on the multilayer ceramic green sheet laminated in the step S3 on a static press;
s5, cutting: cutting the laminated multilayer ceramic green sheet obtained in the step S4 to form a plurality of chip green bodies with specific dimensional accuracy and good consistency;
s6, removing glue: putting the chip green body prepared in the step S5 into a bell-type furnace for drying and discharging glue, and drying and discharging redundant glue solution;
s7, sintering: placing the chip subjected to the glue discharging in the step S6 into a mesh belt type tunnel resistance furnace for sintering, and forming a capacitor matrix;
s8, end processing: and (4) performing end processing on the capacitor base body sintered in the step S7 to form the laminated ceramic capacitor.
By adopting the technical scheme, the long edge of one side of the rectangular ceramic green sheet is used as a printing reference edge, the rectangular inner electrode area is printed on the upper surface of the rectangular ceramic green sheet, and the non-electrode area is formed between the rectangular inner electrode area and the edge of the rectangular ceramic green sheet, so that the inner electrode area capable of transversely transmitting current is formed on the upper surface of the rectangular ceramic green sheet, the internal resistance of the electrode during current transmission is effectively reduced, the heat productivity of the capacitor during use is reduced, and the current transmission efficiency and the safety of the capacitor during use are improved.
When in lamination, 3 layers of rectangular ceramic blank green sheets are respectively left at the bottom and the top to be used as upper and lower end covers, and the rectangular ceramic blank green sheets are not printed with internal electrodes, so that the thickness of the upper and lower end covers of the capacitor can be ensured on the premise of reducing the volume of the capacitor as much as possible, and the effect of improving the protection strength of the internal electrodes of the capacitor is achieved.
Further, the ceramic powder in the step S1 is MgTiO3-CaTiO3-TiO2-Nb2O5-Nd2O3-Bi2O3A multicomponent dielectric ceramic powder.
By adopting the technical scheme, the multi-element dielectric ceramic powder has higher dielectric constant, better electric strength, lower dielectric loss rate and stable capacitance performance, does not change along with the change of temperature, voltage and time basically, is a capacitor dielectric material with ultra-stability, low loss and low parasitic inductance, and has great advantages for preparing a capacitor with small volume, large specific volume and long service life.
Further, in the step S4, the static pressure is 34-42 MPa, the static pressure time is 20-30 min, and the temperature is 50-60 ℃.
By adopting the technical scheme, the multilayer ceramic green sheets are subjected to static pressure pressing by applying equal voltage, so that the multilayer ceramic green sheets are better bonded to form the laminated ceramic green sheets, thereby achieving the effects of reducing the thickness range among the multilayer ceramic green sheets and improving the performance of the laminated ceramic capacitor.
Further, the glue discharging temperature in the step S6 is 185-350 ℃, and the glue discharging time is 50-60 hours.
By adopting the technical scheme, the organic binder added in the ceramic powder can be decomposed and discharged, thereby being beneficial to further molding of the multilayer ceramic green sheet.
Further, in the step S7, the sintering temperature is 1050-1400 ℃, and the sintering time is 1-4 hours.
By adopting the technical scheme, the ceramic green sheets which are laminated together are calcined at high temperature and sintered into a whole, so that the multilayer ceramic capacitor substrate is prepared.
Further, the sintering specifically comprises a temperature rising section, a heat preservation section, a temperature reduction section and a tempering section, and the sintering atmosphere is air.
By adopting the technical scheme, the temperature of the sintering kiln is mainly raised to the temperature of the main sintering temperature zone according to the temperature-raising curve in the temperature-raising section, the chip green bodies after glue removal are subjected to primary sintering in the process, the temperature of the chip green bodies is gradually increased, and the probability of cracking of the chip green bodies caused by too fast temperature rise is reduced; the heat preservation section is used for staying and sintering for a period of time when the temperature is raised to the temperature of the main sintering temperature zone, and the sintering combination of the multilayer ceramic green sheets is accelerated mainly through the heat preservation sintering process; the cooling section and the tempering section can enable the multilayer ceramic green sheet to obtain better reaction, thereby further improving the performance and the quality of the sintered capacitor.
Further, the end processing in the step S8 specifically includes the following steps:
s801, placing the sintered capacitor matrix into a chamfering machine for chamfering and grinding, and exposing the inner electrodes at two ends of the capacitor matrix through chamfering and grinding;
s802, bonding silver paste outside the inner electrode exposed at the end part, and roasting the capacitor matrix bonded with the silver paste to form a substrate electrode;
and S803, forming an external electrode on the outer surface of the substrate electrode in a lead-free electroplating mode, and finally obtaining the finished product of the laminated ceramic capacitor.
Through adopting above-mentioned technical scheme, grind the chamfer to the capacitor base member, make each corner of capacitor base member form the transition fillet to avoid the electric capacity to take place the peak discharge and puncture the electric capacity when high pressure, thereby reach the effect that improves electric capacity work safety nature.
Further, the chamfer grinding material in the step S801 is silicon carbide or calcite grinding beads with the diameter of 10 mu m-1 mm.
By adopting the technical scheme, the silicon carbide and calcite grinding beads are uniform in granularity, good in grinding performance of materials, high in wear resistance and chemical resistance, ideal in grinding material and capable of achieving the effect of improving grinding quality and grinding uniformity of the capacitor.
Further, in the step S802, the roasting temperature is 800 ℃, and the roasting time lasts for 15 min.
By adopting the technical scheme, the silver paste coated and sealed at the end part of the capacitor can be sintered and solidified by roasting, so that a stable external electrode is formed.
In conclusion, the invention has the following beneficial effects:
1. according to the invention, one long side of the rectangular ceramic green sheet is taken as a printing reference side, a rectangular inner electrode region is printed on the upper surface of the rectangular ceramic green sheet, and a non-electrode region is formed between the rectangular inner electrode region and the edge of the rectangular ceramic green sheet, so that the inner electrode region capable of transversely transmitting current is formed on the upper surface of the rectangular ceramic green sheet, the internal resistance of the electrode during current transmission is effectively reduced, the heat productivity of a capacitor during use is reduced, and the current transmission efficiency and the safety of the capacitor during use are improved;
2. the ceramic powder in the invention is MgTiO3-CaTiO3-TiO2-Nb2O5-Nd2O3-Bi2O3The polynary dielectric ceramic powder material with high electric strength resistance, low dielectric loss rate and stable capacitance performance can effectively improve the stability of the capacitor and reduce capacitance loss and parasitic inductance, thereby achieving the effect of preparing the capacitor with small volume, large specific volume and long service life;
3. in the invention, 3 layers of rectangular ceramic blank green sheets are respectively left at the bottom and the top of the rectangular ceramic green sheets as the upper end cover and the lower end cover when the rectangular ceramic green sheets are laminated, and the rectangular ceramic blank green sheets are not printed with the internal electrodes, so that the thickness of the upper end cover and the lower end cover of the capacitor can be ensured on the premise of possibly reducing the volume of the capacitor, and the effect of improving the protection strength of the internal electrodes of the capacitor is further achieved.
Drawings
FIG. 1 is a schematic structural view of a multilayer ceramic green sheet printing stack in an example;
FIG. 2 is a schematic view showing the flow of current to the inner electrode of the ceramic green sheet in the example;
fig. 3 is a schematic diagram showing the printing position relationship of the internal electrodes on the surface of the ceramic sheet and the current flowing direction of the internal electrodes in the background art.
In the figure, 1, a rectangular ceramic blank green sheet; 2. a rectangular ceramic green sheet; 21. a rectangular inner electrode area; 22. a non-electrode region.
Detailed Description
The present invention will be described in further detail with reference to the following examples.