Conductive silver paste for impact-resistant ceramic dielectric capacitor as well as preparation method and application of conductive silver paste

Abstract

The invention relates to conductive silver paste for an impact-resistant ceramic dielectric capacitor and a preparation method and application thereof, and relates to the technical field of silver paste. The conductive silver paste for the impact-resistant ceramic dielectric capacitor comprises the following raw materials in parts by weight: 50-70 parts of silver powder, 1-5 parts of an adhesive, 1-5 parts of an inorganic additive, 20-40 parts of an organic carrier, 1-10 parts of a curing agent and 1-5 parts of a coupling agent. The conductive silver paste has excellent impact resistance and adhesive force after being printed, the problem that a silver layer formed by the silver paste on the surface of the ceramic dielectric capacitor is easy to fall off after mutual collision can be solved, the problem that the adhesive force of the silver layer on the ceramic dielectric capacitor is low is solved, and the application of the silver paste in the ceramic dielectric capacitor is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of silver paste, and in particular to a conductive silver paste for impact-resistant ceramic capacitors, a preparation method and an application thereof. Background Art

[0002] Conductive silver paste is a key functional material required by the electronic components, integrated circuits and solar cell industries, with huge market demand and technological progress potential. Conductive silver paste can be cured on ceramic capacitors to form a conductive network through screen printing, leveling, drying, sintering and other processes, and can be made into thick film integrated circuits, resistors, resistor networks, capacitors, multilayer ceramic capacitors and other electronic components. Conductive silver paste occupies an important position in the information and electronics fields with its high quality, high efficiency, advanced technology and wide applicability, and is widely used in aviation, aerospace, electronic computers, medical equipment, automotive industry, sensors and many other fields.

[0003] However, in actual production, a large number of substrates after drying are usually collected by dumping, resulting in collisions between ceramic dielectric capacitors, thereby causing the silver layer on the substrate surface to fall off, ultimately affecting electrical performance. In addition, due to the presence of powder on the substrate surface, the silver layer formed by sintering the conductive silver paste has poor adhesion. Therefore, it is urgent to propose a conductive silver paste that can make the sintered silver layer have stronger impact resistance and higher adhesion to solve the above problems. Summary of the invention

[0004] In view of the above problems, the present invention provides a conductive silver paste for impact-resistant ceramic capacitors. The conductive silver paste has excellent impact resistance and adhesion after printing. It can not only solve the problem that the silver layer formed on the surface of the silver paste ceramic capacitor is easy to fall off after mutual collision, but also overcome the problem of low adhesion of the silver layer on the ceramic capacitor, which is more conducive to the application of silver paste in ceramic capacitors.

[0005] In order to achieve the above object, the present invention provides a conductive silver paste for impact-resistant ceramic capacitors, comprising the following raw materials in parts by weight:

[0006]

[0007] The formula of the above-mentioned conductive silver paste, by introducing a curing agent and a coupling agent, makes the silver layer formed by the conductive silver paste on the surface of the ceramic capacitor difficult to fall off after mutual collision, and has higher adhesion. The addition of the curing agent can form a network structure between the molecular chains of the polymer resin, and is also a part of the solidified material, thereby changing the matrix resin structure, not only can improve the bonding strength of the conductive silver paste, but also reduce the volume of the resin, so that inorganic materials (such as silver powder, glass powder, etc.) can be in close contact inside the resin, improve the compactness of the silver layer, thereby improving the silver layer shedding phenomenon. In addition, appropriate curing can also enhance the adhesion performance of the silver paste.

[0008] In addition, since the coupling agent can better connect inorganic materials (such as silver powder, glass powder, etc.) and organic resins, an active organic monolayer is formed between the inorganic and organic interfaces. One end is combined with the surface of the inorganic material, and the other end is chemically reacted or physically entangled with the organic material, thus forming an organically combined whole, so that the silver paste forms a dense silver layer on the surface of the ceramic capacitor. The coupling agent can also improve the wettability and dispersibility of the inorganic material in the resin, enhance the adhesion of the silver paste, and thus improve the phenomenon of silver layer shedding.

[0009] In one embodiment, the curing agent includes at least one of methylimidazole, dicyandiamide, adipic acid dihydrazide, methylhexahydrophthalic anhydride, metaphenylenediamine, and tetramethylguanidine.

[0010] In one embodiment, the curing agent includes at least one of methylimidazole, dicyandiamide, and methylhexahydrophthalic anhydride.

[0011] In one embodiment, the curing agent includes at least two of methylimidazole, dicyandiamide, adipic acid dihydrazide, methylhexahydrophthalic anhydride, metaphenylenediamine, and tetramethylguanidine; and the weight proportions of the raw materials in the curing agent are the same.

[0012] In one embodiment, the coupling agent includes at least one of γ-aminopropyl triethoxysilane, β-(3,4-epoxycyclohexane)ethyl trimethoxysilane, isopropyl triisostearyl titanate, γ-methacryloxypropyl trimethoxysilane, tetraisopropyl di(dioctylphosphite) titanate, and isopropyl distearate acyloxyaluminate.

[0013] In one embodiment, the coupling agent includes at least one of γ-aminopropyl triethoxysilane, isopropyl triisostearyl titanate, and isopropyl distearate acyloxyaluminate.

[0014] In one embodiment, the coupling agent includes at least two of γ-aminopropyl triethoxysilane, β-(3,4-epoxycyclohexane)ethyl trimethoxysilane, isopropyl triisostearyl titanate, γ-methacryloxypropyl trimethoxysilane, tetraisopropyl di(dioctylphosphite) titanate, and isopropyl distearate acyloxyaluminate; and the weight proportions of the raw materials in the coupling agent are the same.

[0015] In one embodiment, the adhesive includes lead-free glass powder;

[0016] The lead-free glass powder comprises the following raw materials in parts by weight: 35-65 parts of Bi2O3, 10-30 parts of SiO2, 15-35 parts of B2O3, and 4-20 parts of ZnO;

[0017] The inorganic additive includes a simple substance and / or an oxide of a metal, and the metal includes at least one of Ni, Zn, Cu, Fe, Co, Ti, Al, Mg, and Zr.

[0018] In one embodiment, the weight portion of the lead-free glass powder in the conductive silver paste is 1.5 parts.

[0019] In one embodiment, the inorganic additive includes Ni powder, and the weight portion of the Ni powder in the conductive silver paste is 2 parts.

[0020] In one embodiment, the silver powder is spherical silver powder, and the silver powder includes at least one of silver powder with a particle size of 0.3-0.8 μm, silver powder with a particle size of 1.0-1.5 μm, and silver powder with a particle size of 2.0-5.0 μm.

[0021] In one of the embodiments, the weight portion of silver powder in the conductive silver paste is 60 parts, and the silver powder includes silver powder with a particle size of 0.3-0.8 μm and silver powder with a particle size of 1.0-1.5 μm.

[0022] In one of the embodiments, in the conductive silver paste, the weight ratio of the silver powder with a particle size of 0.3-0.8 μm to the silver powder with a particle size of 1.0-1.5 μm is (4.5-5.5):1.

[0023] In one embodiment, the organic carrier comprises the following raw materials in parts by weight:

[0024] Solvent 30-80 parts

[0025] Resin 5-25 parts

[0026] 1-25 parts of organic additives.

[0027] In one embodiment, the solvent includes at least one of diethylene glycol ethyl ether, methyl phthalate, and pinene alcohol; the resin includes at least one of ethyl cellulose, butyral resin, epoxy resin, polyester resin, acrylic resin, dammar resin, and terpene resin; the organic additive includes at least one of tributyl citrate, dibutyl phthalate, castor oil, oleic acid, and Span 85.

[0028] In one embodiment, the solvent includes methyl phthalate, the resin includes ethyl cellulose, butyral resin, epoxy resin and polyester resin, and the organic additive includes tributyl citrate, oleic acid and Span 85.

[0029] In one embodiment, in the resin, the weight ratio of ethyl cellulose, butyral resin, epoxy resin and polyester resin is (2-4):(1-3):(1-3):(2-4); in the organic additive, the weight ratio of tributyl citrate, oleic acid and Span 85 is 1:1:(1-3).

[0030] In one of the embodiments, the fineness of the conductive silver paste for the impact-resistant ceramic capacitor is ≤10 μm, and the viscosity is 300-500 dPa·s.

[0031] The present invention also provides a method for preparing the conductive silver paste for the impact-resistant ceramic capacitor, comprising the following steps:

[0032] Preparation of adhesive: weighing raw materials of the adhesive, mixing, heating to a melting temperature, maintaining a constant temperature to obtain a molten material, water quenching, ball milling, drying, and sieving the molten material to obtain the adhesive;

[0033] Preparation of organic carrier: weighing raw materials of organic carrier, mixing, heating, stirring until the raw materials are dissolved, filtering, and obtaining organic carrier;

[0034] Preparation of conductive silver paste for impact-resistant ceramic capacitors: weighing silver powder, adhesive, inorganic additives, organic carrier, curing agent, coupling agent, mixing, grinding and mixing to obtain conductive silver paste for impact-resistant ceramic capacitors.

[0035] In one embodiment, in the step of preparing the binder, the melting temperature is 900-1200° C., and the constant temperature time is 3.0-5.0 h;

[0036] In the step of preparing the organic carrier, the temperature is raised to 160-200°C.

[0037] In one embodiment, in the step of preparing the organic carrier, the filtration is achieved by using a filter screen, and the mesh size of the filter screen is 250-350 meshes.

[0038] The present invention also provides a ceramic capacitor, comprising a substrate and the conductive silver paste for the impact-resistant ceramic capacitor.

[0039] The present invention also provides a method for preparing the ceramic capacitor, comprising the following steps:

[0040] Printing: Printing the impact-resistant ceramic capacitor on the surface of the substrate with conductive silver paste using a screen printing method;

[0041] Sintering: The printed substrate is dried and sintered to obtain an impact-resistant ceramic capacitor.

[0042] In one embodiment, the drying temperature is 180-220° C., and the drying time is 3-7 minutes; the sintering condition is: 650-850° C., constant temperature for 5-15 minutes.

[0043] The present invention also provides application of the conductive silver paste for impact-resistant ceramic capacitors in preparing ceramic capacitors.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention discloses a conductive silver paste for impact-resistant ceramic capacitors, a preparation method and an application thereof. The conductive silver paste is printed on a substrate, and after drying and sintering, a silver layer is formed, which has excellent impact resistance and solves the problem of the silver layer falling off due to mutual collision of ceramic capacitors during sorting or transportation. At the same time, the silver layer also has good adhesion and solves the problem of low adhesion performance of the silver layer after printing on the surface of the substrate and sintering. Moreover, the silver layer prepared based on the conductive silver paste has a bright white silver surface after sintering, is easy to weld and has excellent electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 1 is a comparison diagram of the silver surface morphology of the ceramic dielectric capacitor after sintering in the embodiment of the present invention and the comparative example, wherein ae corresponds to the embodiment 1, the comparative example 1, the embodiment 2, the embodiment 3 and the embodiment 4 respectively;

[0047] Figure 2 : is a comparison diagram of the silver surface morphology of the ceramic dielectric capacitor after impact performance test and sintering after drying for the embodiment of the present invention and the comparative example, wherein ae corresponds to the embodiment 1, the comparative example 1, the embodiment 2, the embodiment 3 and the embodiment 4 respectively;

[0048] Figure 3 The figure is a comparison chart of the adhesion performance of the ceramic dielectric capacitor sheets after sintering of the embodiment of the present invention and the comparative example. DETAILED DESCRIPTION

[0049] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0051] source:

[0052] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0053] Example 1

[0054] 1. Preparation of conductive silver paste for impact-resistant ceramic capacitors.

[0055] The conductive silver paste for impact-resistant ceramic capacitors of this embodiment is composed of the following raw materials in parts by weight: 60.0 parts of silver powder, 1.5 parts of glass powder, 2.0 parts of inorganic additives, 33.5 parts of organic carriers, 2.0 parts of curing agent and 1.0 parts of coupling agent.

[0056] The silver powder is composed of silver powder with a particle size of 0.3-0.8μm (accounting for 50.0 parts of the total mass of the conductive silver paste) and silver powder with a particle size of 1.0-1.5μm (accounting for 10.0 parts of the total mass of the conductive silver paste), that is, in this embodiment, the weight ratio of silver powder with a particle size of 0.3-0.8μm to silver powder with a particle size of 1.0-1.5μm is 5:1.

[0057] The inorganic additive is Ni powder.

[0058] The organic vehicle is made of the following raw materials in parts by weight: 6.0 parts of ethyl cellulose (resin), 4.0 parts of butyral resin (resin), 4.0 parts of epoxy resin (resin), 6.0 parts of polyester resin (resin), 1.0 parts of tributyl citrate (organic additive), 2.0 parts of Span 85 (organic additive), 1.0 parts of oleic acid (organic additive) and 76.0 parts of dibutyl phthalate (solvent). That is, in this embodiment, the weight ratio of solvent, resin and organic additive is 76:20:4; the weight ratio of ethyl cellulose, butyral resin, epoxy resin and polyester resin in the resin is 3:2:2:3; the weight ratio of tributyl citrate, oleic acid and Span 85 in the organic additive is 1:1:2.

[0059] The curing agent is methylimidazole and dicyandiamide, and the weight ratio of methylimidazole to dicyandiamide is 1:1.

[0060] The coupling agent is γ-aminopropyl triethoxysilane and triisostearyl isopropyl titanate, and the weight ratio of γ-aminopropyl triethoxysilane to triisostearyl isopropyl titanate is 1:1.

[0061] The method for preparing the conductive silver paste for the impact-resistant ceramic capacitor comprises the following steps:

[0062] (1) Preparation of glass powder: Weigh the raw materials according to the formula and mix them evenly (in this embodiment, the glass powder is lead-free glass powder, and the raw materials are: 50 parts of Bi2O3, 20 parts of SiO2, 20 parts of B2O3, and 10 parts of ZnO), adjust the melting temperature to 1200°C and keep the temperature constant for 4 hours, quench the molten material with water, ball mill, dry and sieve, and obtain glass powder with a particle size of 2.0 μm;

[0063] (2) Preparation of organic carrier: weigh the raw materials of the organic carrier according to the formula and mix them evenly, heat to 200° C., stir until the raw materials are completely dissolved, and then filter through a 300-mesh filter to obtain an organic carrier;

[0064] (3) Preparation of conductive silver paste: Silver powder, glass powder, organic carrier, inorganic additive, curing agent and coupling agent are weighed according to the formula, and pre-mixed, and then ground and mixed on a three-roll mill to obtain the conductive silver paste for impact-resistant ceramic capacitors (fineness of 9.0 μm, viscosity of 350 dPa·s).

[0065] A method for using conductive silver paste for impact-resistant ceramic capacitors comprises the following steps:

[0066] (1) Printing the prepared conductive silver paste on a ceramic capacitor (mesh size: 250 mesh) by screen printing;

[0067] (2) Drying and sintering the ceramic capacitor printed with the conductive silver paste to form the impact-resistant ceramic capacitor, wherein the drying condition is drying at 200° C. for 5 minutes, and the sintering condition is constant temperature at 800° C. for 10 minutes.

[0068] The sintering is preferably carried out in the form of co-firing, that is, after both sides of the ceramic capacitor are completely printed, they are put into a sintering furnace together for sintering to form the final ceramic capacitor.

[0069] Comparative Example 1

[0070] This comparative example is substantially the same as Example 1, except that no curing agent and coupling agent are used.

[0071] Example 2

[0072] The difference between this embodiment and embodiment 1 is that the types of curing agents are different, that is, the curing agent is composed of methylimidazole and methylhexahydrophthalic anhydride, and the weight ratio of methylimidazole to methylhexahydrophthalic anhydride in the curing agent is 1:1.

[0073] Example 3

[0074] The difference between this embodiment and embodiment 1 is that the types of coupling agents are different, that is, the coupling agent is composed of γ-aminopropyl triethoxysilane and isopropyl distearate acyloxyaluminate, and the weight ratio of γ-aminopropyl triethoxysilane and isopropyl distearate acyloxyaluminate in the coupling agent is 1:1.

[0075] Example 4

[0076] The difference between this embodiment and embodiment 1 is that the types of curing agent and coupling agent are different, that is, the curing agent is dicyandiamide and the coupling agent is γ-aminopropyltriethoxysilane.

[0077] Experimental example

[0078] 1. The ceramic capacitors prepared by the conductive silver paste in each embodiment were tested.

[0079] The impact performance test of the dried ceramic capacitors and the adhesion performance test of the sintered ceramic capacitors were performed.

[0080] (1) Impact resistance test method: The ceramic capacitor is continuously impacted against the dried ceramic capacitor 20 times (on the same side) at the same height (10 cm).

[0081] (2) Adhesion test method: After the sintered ceramic capacitor is welded, the adhesion data is directly read by an adhesion tester (n=10).

[0082] 2. Experimental results.

[0083] from Figure 1 (ae correspond to Example 1, Comparative Example 1, Example 2, Example 3 and Example 4 respectively) It can be seen that a small amount of holes and black spots appear in the silver paste of Comparative Example 1, and the surface morphology is poor ( Figure 1 b); By adding curing agent and coupling agent to the silver paste, the holes can be effectively reduced, the flatness is better, the silver layer is dense and seamless, and the continuity is good ( Figure 1 a, ce).

[0084] from Figure 2 (ae correspond to Example 1, Comparative Example 1, Example 2, Example 3 and Example 4 respectively) It can be seen that after 20 consecutive impacts, the silver layer on the surface of the ceramic capacitor printed with the silver paste of Comparative Example 1 fell off in large quantities, exposing the substrate surface ( Figure 2b). By adding curing agent and coupling agent to the silver paste, the silver layer shedding phenomenon was significantly improved, and the structure remained generally intact ( Figure 2 a, ce), indicating that the silver surface is relatively dense and has high hardness, which effectively protects the silver layer on the surface of the substrate.

[0085] from Figure 3 It can be seen that compared with Comparative Example 1, after adding a curing agent and a coupling agent to the silver paste, the adhesion is increased by 2.2-3.8 times, which further demonstrates that the conductive silver paste of the present invention has excellent performance.

[0086] In summary, after adding curing agent and coupling agent to silver paste, the silver layer on the surface of the substrate can be effectively protected due to the improvement of the density of the silver layer and the enhancement of the adhesion of the silver paste. Therefore, there is no need to worry about the dumping of a large number of substrates during the production process, which provides more favorable conditions for production and guarantees for obtaining better products.

[0087] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A conductive silver paste for impact-resistant ceramic capacitors, characterized in that: The invention comprises the following raw materials in parts by weight:

2. The conductive silver paste for impact-resistant ceramic capacitors according to claim 1, characterized in that: The curing agent includes at least one of methylimidazole, dicyandiamide, adipic acid dihydrazide, methylhexahydrophthalic anhydride, metaphenylenediamine, and tetramethylguanidine.

3. The conductive silver paste for impact-resistant ceramic capacitors according to claim 1, characterized in that: The coupling agent includes at least one of γ-aminopropyl triethoxysilane, β-(3,4-epoxycyclohexane)ethyl trimethoxysilane, isopropyl triisostearyl titanate, γ-methacryloxypropyl trimethoxysilane, tetraisopropyl di(dioctylphosphite) titanate, and isopropyl distearate acyloxyaluminate.

4. The conductive silver paste for impact-resistant ceramic capacitors according to claim 1, characterized in that: The adhesive includes lead-free glass powder; The lead-free glass powder comprises the following raw materials in parts by weight: 35-65 parts of Bi2O3, 10-30 parts of SiO2, 15-35 parts of B2O3, and 4-20 parts of ZnO; The inorganic additive includes a simple substance and / or an oxide of a metal, and the metal includes at least one of Ni, Zn, Cu, Fe, Co, Ti, Al, Mg, and Zr.

5. The conductive silver paste for impact-resistant ceramic capacitors according to claim 1, characterized in that: The organic carrier comprises the following raw materials in parts by weight: Solvent 30-80 parts Resin 5-25 parts 1-25 parts of organic additives.

6. The conductive silver paste for impact-resistant ceramic capacitors according to claim 5, characterized in that: The solvent includes at least one of diethylene glycol ethyl ether, methyl phthalate, and pinene alcohol; the resin includes at least one of ethyl cellulose, butyral resin, epoxy resin, polyester resin, acrylic resin, dammar resin, and terpene resin; and the organic additive includes at least one of tributyl citrate, dibutyl phthalate, castor oil, oleic acid, and Span 85.

7. The method for preparing the conductive silver paste for impact-resistant ceramic capacitors according to any one of claims 1 to 6, characterized in that: The following steps are involved: Preparation of adhesive: weighing raw materials of the adhesive, mixing, heating to a melting temperature, maintaining a constant temperature to obtain a molten material, water quenching, ball milling, drying, and sieving the molten material to obtain the adhesive; Preparation of organic carrier: weighing raw materials of organic carrier, mixing, heating, stirring until the raw materials are dissolved, filtering, and obtaining organic carrier; Preparation of conductive silver paste for impact-resistant ceramic capacitors: weighing silver powder, adhesive, inorganic additives, organic carrier, curing agent, coupling agent, mixing, grinding and mixing to obtain conductive silver paste for impact-resistant ceramic capacitors.

8. The preparation method according to claim 7, characterized in that: In the step of preparing the binder, the melting temperature is 900-1200° C., and the constant temperature time is 3.0-5.0 h; In the step of preparing the organic carrier, the temperature is raised to 160-200°C.

9. A ceramic capacitor, characterized in that: The invention comprises a substrate and a conductive silver paste for an impact-resistant ceramic capacitor as claimed in any one of claims 1 to 6.

10. Use of the conductive silver paste for impact-resistant ceramic capacitors according to any one of claims 1 to 6 in the preparation of ceramic capacitors.

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