阅读说明：本技术 一种mlcc电容器 (MLCC capacitor ) 是由 穆开洪 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种MLCC电容器,包括多层复合陶瓷体以及形成于多层复合陶瓷体两侧端面上的端电极；所述多层复合陶瓷体是将铜箔复合层、铝箔复合层依次间隔叠放在一起后,经轧制后得到的；铜箔复合层包括铜箔以及涂布于铜箔表面的复合涂层,铝箔复合层包括铝箔以及涂布于铝箔表面的复合涂层；其中,复合涂层是由塑料粒子与陶瓷颗粒形成的浆料涂布在铜箔/铝箔上经烘干固化后得到的；所述轧制的温度处于塑料粒子的软化温度与熔点之间。本发明的MLCC电容器,使用了铜箔、铝箔、塑料和陶瓷颗粒形成复合材料制作,不仅简化了工序,节省了能源,而且避免了传统工艺中一直存在的镍粉和钛酸钡粉烧结不当,产生的短路和断路等质量问题。(The invention discloses an MLCC capacitor, which comprises a multilayer composite ceramic body and terminal electrodes formed on the end surfaces of two sides of the multilayer composite ceramic body; the multilayer composite ceramic body is obtained by sequentially stacking a copper foil composite layer and an aluminum foil composite layer at intervals and rolling; the copper foil composite layer comprises a copper foil and a composite coating coated on the surface of the copper foil, and the aluminum foil composite layer comprises an aluminum foil and a composite coating coated on the surface of the aluminum foil; wherein, the composite coating is obtained by coating slurry formed by plastic particles and ceramic particles on a copper foil/aluminum foil and drying and curing the slurry; the rolling temperature is between the softening temperature and the melting point of the plastic particles. The MLCC capacitor is made of the composite material formed by the copper foil, the aluminum foil, the plastic and the ceramic particles, so that the working procedures are simplified, the energy is saved, and the quality problems of short circuit, open circuit and the like caused by improper sintering of the nickel powder and the barium titanate powder in the traditional process are avoided.)

1. An MLCC capacitor, characterized in that, the MLCC capacitor comprises a multilayer composite ceramic body and end electrodes formed on the end faces of two sides of the multilayer composite ceramic body; the multilayer composite ceramic body is obtained by sequentially stacking a copper foil composite layer and an aluminum foil composite layer at intervals and rolling; the copper foil composite layer comprises a copper foil and a composite coating coated on the surface of the copper foil, and the aluminum foil composite layer comprises an aluminum foil and a composite coating coated on the surface of the aluminum foil;

the composite coating is obtained by coating slurry formed by plastic particles and ceramic particles on a copper foil/aluminum foil and drying and curing the slurry; the rolling temperature is between the softening temperature and the melting point of the plastic particles.

2. The MLCC capacitor of claim 1, wherein the plastic particles comprise one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate.

3. The MLCC capacitor according to claim 1, wherein the ceramic particles comprise one or more of barium titanate, alumina, zirconia, aluminum nitride, boron nitride, and silicon nitride.

4. The MLCC capacitor according to claim 3, wherein the ceramic particles have a particle size of 0.2-5 μm.

5. The MLCC capacitor according to claim 1, wherein the slurry is prepared by dissolving the plastic particles in an organic solvent, mixing the plastic particles with the ceramic particles, and stirring, wherein the organic solvent comprises one or more of toluene, xylene, chloroform, N-methylpyrrolidone, DMF, acetone, and ethyl acetate.

6. The MLCC capacitor according to claim 1, wherein the mass ratio of the ceramic particles in the slurry is 20-70%.

7. The MLCC capacitor according to claim 1, wherein the copper foil and the aluminum foil are pure copper foil and pure aluminum foil, respectively, and have a thickness of 6-20 μm; the thickness of the composite coating is 5-50 μm.

8. The MLCC capacitor according to claim 1, wherein the multilayer composite ceramic body comprises 10-1000 stacked layers of the copper foil composite layer and the aluminum foil composite layer.

9. The MLCC capacitor according to claim 1, wherein the thickness of the multilayer composite ceramic body is between 0.05 and 100 mm.

10. The MLCC capacitor according to claim 1, wherein the terminal electrodes are formed by melting the copper foils/aluminum foils on the two side end surfaces of the multilayer composite ceramic body and then connecting the remaining aluminum foils/copper foils together by soldering.

Technical Field

The invention relates to the technical field of capacitors, in particular to an MLCC capacitor.

Background

Today, the electronic information industry is rapidly developing, various electronic information products such as notebook computers, mobile phones, liquid crystal televisions, video cameras and the like bring great convenience to life of people, and electric appliance products are smaller and smaller than before and have more and more complete functions. All of the functions are attributed to the fact that semiconductor components and numerous passive patch elements which are the core of electric products are increasingly miniaturized, have high precision and low power consumption, and information products such as household appliances and the like are miniaturized. This puts a higher demand on the metal sheet multilayer ceramic capacitor (MLCC capacitor), one of the main passive chip components in the whole machine.

Generally, in the manufacturing of the MLCC capacitor, a nickel internal electrode is printed on a ceramic sheet, then the barium titanate ceramic sheet printed with the internal electrode is mutually overlapped to a certain number of layers according to requirements, the barium titanate ceramic sheet is sintered into a whole at a high temperature, then copper paste is coated on two ends, electrodes at two ends are formed by sintering the ends, and finally a nickel layer and a tin layer are plated on copper, so that the MLCC capacitor is manufactured, wherein the schematic diagram of the MLCC capacitor is shown in fig. 1. The high-capacitance product generally has more than 100 layers, and some products even have 400-500 layers, so the thickness of each layer is required to be very thin, the thickness of a medium is required to be 1-3 mu m, the thickness of a printing layer is required to be 0.5-1 mu m, the requirement of the facing area between the inner electrode layers is larger and better due to the higher number of the layers, and the sintered MLCC capacitor is shown in figure 2.

The inner electrode of the traditional MLCC capacitor is made of silver paste containing noble metal palladium at first, and the price is very expensive, so that a plurality of manufacturers try to reduce the cost. The existing production method adopts superfine nickel powder to prepare nickel slurry to replace silver palladium slurry as an inner electrode material. At present, the method for preparing nickel powder mainly comprises the following steps: liquid phase reduction, spray pyrolysis, plasma, gas phase, solid phase decomposition, and the like. The particle size and distribution of the nickel powder determine the thickness of the electrode layer, and the uniform spherical nickel powder can form a smooth inner electrode layer, and the nickel powder should have the following properties: spherical, uniform and moderate granularity, high purity and high crystallinity. However, the current nickel powder and nickel slurry have the following problems:

(1) the metal powder of the MLCC nickel inner electrode is usually submicron to nanometer, has high surface activity and is easy to oxidize, so that the conductivity and weldability of the metal powder are influenced, and the nickel powder of the inner electrode is required to have higher oxidation resistance.

(2) When the nickel inner electrode layer is co-sintered with the barium titanate ceramic dielectric layer, the problem of sintering matching between the nickel inner electrode layer and the ceramic dielectric layer needs to be solved because the shrinkage characteristics of the ceramic medium and the nickel inner electrode layer are different.

(3) The problem of agglomeration of the ultrafine nickel powder needs to be solved. If the dispersibility of the nickel powder is poor, when the lamination and cutting operations of the MLCC lamination body are carried out, the nickel powder agglomeration part penetrates through the dielectric layer due to overlarge stress, so that the electrode layer and the dielectric layer are mixed into a whole, the lamination defect is not generated, the short circuit is formed between the inner electrodes, and the reliability of the MLCC is seriously influenced.

In addition, the MLCC is easy to have quality problems such as ceramic body cracks, capacity super-poor and insulation reduction after welding in the using process, and the factors influencing the MLCC cracking mainly comprise two types: (1) internal cause: mainly relating to the material, internal defects and product size of MLCCs. Meanwhile, various studies have shown that the larger the size of the product, the more easily the product is cracked during welding and installation. (2) External factors: mainly including thermal and mechanical stresses that occur during welding and post-welding operations. The profile analysis is a main analysis means for judging the failure of the MLCC in the panel power supply. Analysis of most samples that failed showed the end electrode to exhibit about 45 ° cracking (fig. 3), which is a typical feature of bend failure-the most stressed site exhibited 45 ° cracking (fig. 4). Therefore, the failure mode of MLCCs is dominated by flex cracking.

At present, MLCC capacitors are developing toward small size, high performance, low dielectric loss, large yield, low price, and the like, so that providing an MLCC capacitor material with low cost, simple process, and environmental friendliness has become a technical problem to be solved in the art.

Disclosure of Invention

The technical problem to be solved by the invention is to provide the MLCC capacitor which is made of the composite material formed by the copper foil, the aluminum foil, the plastic and the ceramic particles, so that the working procedures are simplified, the energy is saved, and the quality problems of short circuit, open circuit and the like caused by improper sintering of the nickel powder and the barium titanate powder in the traditional process are avoided.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides an MLCC capacitor, which comprises a multilayer composite ceramic body and end electrodes formed on the end surfaces of two sides of the multilayer composite ceramic body; the multilayer composite ceramic body is obtained by sequentially stacking a copper foil composite layer and an aluminum foil composite layer at intervals and rolling; the copper foil composite layer comprises a copper foil and a composite coating coated on the surface of the copper foil, and the aluminum foil composite layer comprises an aluminum foil and a composite coating coated on the surface of the aluminum foil;

the composite coating is obtained by coating slurry formed by plastic particles and ceramic particles on a copper foil/aluminum foil and drying and curing the slurry; the rolling temperature is between the softening temperature and the melting point of the plastic particles.

Further, the plastic particles are thermoplastic resins, including but not limited to one or more of Polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), Polystyrene (PS), Polyamide (PA), Polyoxymethylene (POM), Polycarbonate (PC).

Further, the ceramic particles include, but are not limited to, one or more of barium titanate, aluminum oxide, zirconium oxide, aluminum nitride, boron nitride, and silicon nitride.

Further, the ceramic particles have a particle size of 0.2 to 5 μm.

Further, the slurry is obtained by dissolving the plastic particles in an organic solvent, mixing with the ceramic particles, and stirring, wherein the organic solvent includes but is not limited to one or more of toluene, xylene, chloroform, N-methylpyrrolidone, DMF, acetone, and ethyl acetate.

Further, in the slurry, the mass ratio of the ceramic particles is 20-70%.

Further, the copper foil and the aluminum foil are respectively pure copper foil and pure aluminum foil, and the thickness of the copper foil and the pure aluminum foil is 6-20 mu m; the thickness of the composite coating is 5-50 μm.

Furthermore, in the multilayer composite ceramic body, the number of stacked layers of the copper foil composite layer and the aluminum foil composite layer is 10-1000.

Further, the multilayer composite ceramic body has a thickness of 0.05 to 100 mm.

Furthermore, the terminal electrode is obtained by melting the copper foil/aluminum foil on the end surfaces of the two sides of the multilayer composite ceramic body and then connecting the remaining aluminum foil/copper foil together through soldering tin.

Furthermore, the remaining copper foil/aluminum foil is connected with the copper electrode/aluminum electrode first, and then is connected with the external electrode in a soldering tin mode.

Compared with the prior art, the invention has the beneficial effects that:

(1) in the capacitor material, the copper foil, the aluminum foil, the plastic and the ceramic particles are creatively used to form a composite material, so that slurry made of the ceramic and the plastic particles is coated on the copper foil and the aluminum foil;

(2) the copper foil and the aluminum foil are mutually spaced, and are sequentially stacked together layer by layer and are heated and rolled, so that the bonding strength of plastics, ceramics, metal copper foil and aluminum foil is remarkably improved;

(3) compared with the traditional MLCC capacitor, the invention omits the preparation process and the high-temperature sintering process of the nickel powder, not only simplifies the working procedures and saves the energy, but also avoids the quality problems of short circuit, open circuit and the like caused by improper sintering of the nickel powder and the barium titanate powder in the traditional process;

(5) the insulating layer adopts the thermoplastic resin material, so that the toughness of the prepared capacitor is improved, and the cracking phenomenon caused by thermal stress during welding the electrode is avoided.

Drawings

FIG. 1 is a schematic diagram of a prior art MLCC capacitor;

FIG. 2 is a sintered MLCC capacitor;

FIG. 3 is a bend crack section of an MLCC capacitor;

FIG. 4 is a schematic view of a flex crack of an MLCC capacitor;

FIG. 5 is a schematic diagram of the MLCC capacitor of the invention;

the reference numbers in the figures illustrate: 1. copper foil; 2. aluminum foil; 3. a copper electrode; 4. an aluminum electrode; 5. and (7) soldering tin.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The experimental methods used in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used therein are commercially available without otherwise specified.

Example 1

1. Dissolving polycarbonate plastic particles in N-methyl pyrrolidone solvent, adding 40 wt% of barium titanate ceramic particles with the diameter of 1 mu m, stirring into uniform slurry, adjusting the viscosity to a proper value, and then putting the slurry into a coating machine. The coating machine is provided with a copper foil coil material with the thickness of 8 microns, slurry made of ceramic particles and plastic particles is coated on the copper foil with the coating thickness of 6 microns along with the rotation of the coating machine, the copper foil coated with the slurry passes through a dryer at the speed of 2m/mim, the temperature of the dryer is kept at 150 ℃, after the slurry is dried, plastic curing bonding ceramic powder is coated on the surface of the copper foil and bonded together, and the copper foil coated with the plastic and the ceramic powder on the surface is wound. Then, an aluminum foil coated with plastic particles and ceramic particles on the surface thereof was prepared and wound in the same process, and the thickness of the aluminum foil was 8 μm. The dryer is provided with the air draft equipment and the organic solvent absorption equipment, so that the volatilized solvent can be recycled after being absorbed when the slurry is dried, and air pollution is avoided.

2. Cutting the coated copper foil and the coated aluminum foil into sheets as required, stacking the copper foil and the aluminum foil which are coated and separated at intervals in sequence layer by layer, wherein the number of the stacked layers is 50, heating the copper foil and the aluminum foil to the softening point of plastic, then sending the copper foil and the aluminum foil which are stacked in sequence into a reciprocating rolling mill, arranging heating and heat-preserving cavities at two ends of the reciprocating rolling mill, controlling the rolling temperature within the range of 200-220 ℃, gradually reducing the gap between an upper roller and a lower roller, and rolling the copper foil and the aluminum foil which are coated in multiple layers into the sheets with the thickness of 0.1 mm.

3. And cutting the multilayer sheet according to the requirements of different capacitors, and selecting two end surfaces as welding spots for welding with the external electrodes after cutting. Placing one end face before welding into dilute hydrochloric acid, wherein the concentration of the dilute hydrochloric acid is 5%, and dissolving the aluminum foil near the section to leave a copper foil; the other end face was put into concentrated nitric acid having a concentration of 70%, the copper foil in the vicinity of the end face was dissolved, the aluminum was passivated in concentrated nitric acid, and the aluminum foil was left behind, and then the end face was sanded to remove the aluminum passivation layer. The two end faces are respectively soldered with the external electrodes by tin, after the electrodes are welded, the copper foils can be mutually communicated into a whole, and the aluminum foils are mutually connected into a whole, so that the multilayer capacitor is manufactured.

Example 2

1. Dissolving polyethylene plastic particles in an acetone solvent, adding 50 wt% of alumina ceramic particles with the diameter of 2 mu m, stirring into uniform slurry, adjusting to proper viscosity, and putting into a coating machine. The coating machine is provided with a copper foil coil material with the thickness of 10 microns, slurry made of ceramic and plastic particles is coated on the copper foil with the coating thickness of 8 microns along with the rotation of the coating machine, the copper foil coated with the slurry passes through a dryer at the speed of 5m/mim, the temperature of the dryer is kept at 180 ℃, after the slurry is dried, plastic curing bonding ceramic powder is coated on the surface of the copper foil and bonded together, and the copper foil coated with the plastic and the ceramic powder on the surface is wound. And preparing the aluminum foil with the surface coated with the plastic and the ceramic powder by the same process, and rolling the aluminum foil, wherein the thickness of the aluminum foil is 10 mu m. The dryer is provided with the air draft equipment and the organic solvent absorption equipment, so that the volatilized solvent can be recycled after being absorbed when the slurry is dried, and air pollution is avoided.

2. Cutting the coated copper foil and the coated aluminum foil into sheets as required, stacking the coated copper foil and the coated aluminum foil at intervals in sequence layer by layer with the stacking number of 80, and heating to the softening point of the plastic. And then feeding the copper foil and the aluminum foil which are sequentially stacked into a reciprocating rolling mill, wherein heating and heat-insulating cavities are arranged at two ends of the reciprocating rolling mill, the rolling temperature is controlled within the range of 220-240 ℃, the gap between an upper roller and a lower roller is gradually reduced, and the multilayer coated copper foil and aluminum foil material is rolled into a sheet with the thickness of 0.2 mm.

3. And cutting the multilayer sheet according to the requirements of different capacitors, and selecting two end surfaces as welding spots for welding with the external electrodes after cutting. Before welding, one end face is put into dilute hydrochloric acid, the concentration of the dilute hydrochloric acid is 10%, an aluminum foil near the section is dissolved, a copper foil is left, the other end face is put into concentrated nitric acid, the concentration of the concentrated nitric acid is 80%, the copper foil near the end face is dissolved, aluminum is passivated in the concentrated nitric acid, the aluminum foil is left, and then the end face is polished by abrasive paper, so that the aluminum passivation layer is removed. The two end faces are respectively soldered with the external electrodes by tin, after the electrodes are welded, the copper foils can be mutually communicated into a whole, and the aluminum foils are mutually connected into a whole, so that the multilayer capacitor is manufactured.

Example 3

Polyvinyl chloride plastic particles are dissolved in DMF (N, N-dimethylacetamide) solvent, 60 wt% of silicon nitride ceramic particles with the diameter of 3 mu m are added, the mixture is stirred into uniform slurry, and the uniform slurry is placed into a coating machine after the viscosity is adjusted to be proper. The coating machine is provided with a copper foil coil with the thickness of 12 microns, slurry made of ceramic and plastic particles is coated on the copper foil with the coating thickness of 10 microns along with the rotation of the coating machine, the copper foil coated with the slurry passes through a dryer at the speed of 8m/mim, the temperature of the dryer is kept at 200 ℃, after the slurry is dried, plastic curing bonding ceramic powder is coated on the surface of the copper foil and bonded together, and the copper foil coated with the plastic and the ceramic powder on the surface is wound. And preparing the aluminum foil with the surface coated with the plastic and ceramic powder by the same process, and rolling the aluminum foil, wherein the thickness of the aluminum foil is 12 mu m. The dryer is provided with the air draft equipment and the organic solvent absorption equipment, so that the volatilized solvent can be recycled after being absorbed when the slurry is dried, and air pollution is avoided.

2. Cutting the coated copper foil and the coated aluminum foil into sheets as required, stacking the copper foil and the aluminum foil which are coated and separated at intervals in sequence layer by layer, wherein the number of the stacked layers is 100, heating the copper foil and the aluminum foil to the softening point of plastic, then sending the copper foil and the aluminum foil which are stacked in sequence into a reciprocating rolling mill, arranging heating and heat-preserving cavities at two ends of the reciprocating rolling mill, controlling the rolling temperature within the range of 240 plus one temperature and 260 ℃, gradually reducing the gap between an upper roller and a lower roller, and rolling the copper foil and the aluminum foil which are coated in multiple layers into the sheets with the thickness of 0.3 mm.

3. And cutting the multilayer sheet according to the requirements of different capacitors, and selecting two end surfaces as welding spots for welding with the external electrodes after cutting. Before welding, one end face is put into dilute hydrochloric acid, the concentration of the dilute hydrochloric acid is 15%, an aluminum foil near the section is dissolved, a copper foil is left, the other end face is put into concentrated nitric acid, the concentration of the concentrated nitric acid is 90%, the copper foil near the end face is dissolved, aluminum is passivated in the concentrated nitric acid, the aluminum foil is left, and then the end face is polished by abrasive paper, so that the aluminum passivation layer is removed. The two end faces are respectively soldered with the external electrodes by tin, after the electrodes are welded, the copper foils can be mutually communicated into a whole, and the aluminum foils are mutually connected into a whole, so that the multilayer capacitor is manufactured.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.