Electroplating end electrode-based vehicle gauge soft terminal multilayer ceramic capacitor structure and process

Abstract

The invention discloses a vehicle gauge soft terminal multilayer ceramic capacitor structure and process based on an electroplating terminal electrode, the capacitor comprises a laminated ceramic structure, and the laminated ceramic structure is composed of laminated ceramic formed by a plurality of stacked ceramics and an internal electrode layer; the internal electrode layer is made of a nickel material, end electrodes are arranged at the two ends of the laminated ceramic, a soft terminal layer, an external nickel layer and a soldering-aid tin layer are sequentially arranged outside the end electrodes, and the soft terminal layer is prepared from silver paste prepared from silver powder, commercial resin, a curing agent dispersing agent, a catalyst and the like according to a specific proportion. According to the structure and the process, the end electrodes are formed through nickel material electroplating, the process belongs to a low-temperature process, the soft terminal layer with silver paste as a main material plays a role of an elastic layer, effectively absorbs external stress and prevents external impact force of a circuit board from touching a rigid ceramic body of the MLCC, and an MLCC device has high bending resistance and impact resistance. The method can be applied to the fields of vehicle-gauge multi-layer ceramic capacitors (MLCC) and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automotive-grade multilayer ceramic capacitor (MLCC), in particular, and more particularly to an automotive-grade soft terminal multilayer ceramic capacitor structure and process based on electroplated end electrodes. BACKGROUND

[0002] Multilayer ceramic capacitors are the most widely used type of chip component. With the rapid development of electric vehicles and the rapid electrification of traditional fuel vehicles, the demand for automotive-grade MLCCs is growing exponentially.

[0003] However, the daily use environment of automobiles and the high reliability and safety requirements pose extremely stringent demands on traditional MLCCs. Automotive-grade MLCCs must have strong bending resistance and not fall off or crack under strong stress impact or in a large temperature range. Therefore, ordinary MLCC devices cannot meet the requirements of automotive-grade devices.

[0004] Patent "CN 115692017 A Method for Manufacturing Multilayer Ceramic Capacitor End Electrode and Printing Full-area Internal Electrode Protection Layer" discloses a new method for manufacturing a multilayer ceramic capacitor end electrode. The method first provides a sintered multilayer ceramic capacitor without end electrodes. The multilayer ceramic capacitor is formed by alternately stacking a plurality of thin dielectric ceramic layers and a plurality of internal electrodes, and the internal electrodes of the multilayer ceramic capacitor are printed in full area, so that the end edges of the multilayer ceramic capacitor have high-density internal electrodes. The multilayer ceramic capacitor is immersed in a metal solution with a temperature less than 80℃ using a wet chemical immersion plating method. The metal plating film on the surface of the internal electrode is slowly grown by electrochemical deposition at first, and after 1-2 hours of deposition, the metal plating film on the surface of the internal electrode continues to grow and connects together, forming a metal plating film end electrode on the connecting surface of the end edges of the multilayer ceramic capacitor. However, this method has poor bending resistance for automotive-grade MLCCs, and may crack under strong stress impact or in a large temperature range, affecting reliability.

[0005] Patent "CN 102146194 B Conductive resin composition and chip-type electronic component" discloses a method for preparing a conductive resin composition, and mentions that a chip-type capacitor with a resin composition containing the conductive component as an external electrode needs to have a laminated ceramic element with a ceramic layer and internal electrodes. The end electrode is formed by coating copper paste on both end surfaces of the laminated ceramic element and sintering. Finally, a resin layer is coated on the end electrode. However, the copper paste sintered at high temperature has high stress, poor surface density, and high cost.

[0006] Therefore, it is necessary to provide a vehicle-grade soft terminal multilayer ceramic capacitor structure and process based on electroplated end electrodes, so that the MLCC device has strong bending resistance and cracking resistance, and meets the needs of vehicle-grade market applications. SUMMARY

[0007] According to the existing multilayer ceramic capacitor (MLCC) proposed above, the problem of easy peeling and cracking under high temperature difference and high impact force conditions is solved by providing a vehicle-grade soft terminal multilayer ceramic capacitor structure and process based on electroplated end electrodes. The end electrode is formed by electroplating nickel material, which has the same metal material as the internal electrode, good material continuity, and is not easy to peel off. Moreover, it is a low-temperature process with high density. At the same time, the soft terminal layer is designed to be formed between the end electrode and the external nickel layer, which provides elastic medium and further improves the bending resistance of the device.

[0008] The technical means adopted by the present application are as follows: The present application discloses a vehicle-grade soft terminal multilayer ceramic capacitor based on electroplated end electrodes: comprising a laminated ceramic structure composed of a plurality of stacked laminated ceramics and internal electrode layers formed by a plurality of stacked ceramics; The internal electrode layer is made of nickel material, and the internal electrode layer alternately extends to both ends of the laminated ceramic to form an internal electrode nickel material interface. The two ends of the laminated ceramic are provided with end electrodes made of nickel material and formed on the basis of the nickel material interface of the internal electrode. Each layer of the internal electrode layer is connected to only one end of the end electrode; The end electrode is further provided with a soft terminal layer, an external nickel layer and a soldering tin layer in sequence; The soft terminal layer is located between the end electrode and the external nickel layer, and is formed by mixing and processing silver powder, resin, curing agent, dispersing agent, catalyst and organic solvent to form a soft terminal silver paste on the surface of the end electrode, and is cured by a low-temperature curing process. The external nickel layer and the soldering tin layer completely cover the surface of the soft terminal layer.

[0009] Further, in the above technical solution, the raw materials of the soft terminal layer are mixed in the following proportions: Silver powder 60-75 parts; Liquid resin 10-15 parts; Curing agent 0.1-2 parts; Dispersing agent 0.1-2 parts; Catalyst 0.1-2 parts; The mass ratio of resin to organic solvent in the liquid resin is 2-3:7-8.

[0010] Further, in the above technical solution, the soft terminal silver paste used in the soft terminal layer is prepared by: S1, liquid resin preparation: The epoxy resin is mixed and stirred in an organic solvent, including alicyclic epoxy resin, bisphenol A epoxy resin, modified epoxy resin, the weight ratio of the three resins is 2-3:3.5-4.5:2.5-3.5, the mass ratio of the total amount of epoxy resin to organic solvent is 2-3:7-8, the stirring time is 2-3 hours, the stirring speed is 800-1000 rpm, and the stirring temperature is 60-80℃; S2, raw material mixing: The curing agent, catalyst, silver powder, and dispersing agent are sequentially added to the liquid resin obtained in S1, and high-speed stirring is performed at a speed of 1000-1200 rpm for 2-5 min to form a soft-end silver paste. S3, viscosity test: Further, in the above technical solution, it also includes, S3, after plating the end electrode (structure three), test the semi-finished device, dip a small amount of sample of the soft-end silver paste obtained in S2, dry and cure, and observe.

[0011] S4, viscosity adjustment: Based on the observation of the end appearance in S3, if there is obvious protrusion on the end, an appropriate amount of organic solvent is added to the soft-end silver paste obtained in S2, high-speed stirring is performed at 1000-1200 rpm for 2-5 min, and the S3 step is repeated until the physical appearance that meets the requirements is obtained, that is, the end surface is flat and the side is free of flow.

[0012] S5, soft-end silver paste storage: The soft-end silver paste obtained in S4 is sealed and packaged, and stored in cold storage.

[0013] Further, in the above technical solution, the curing agent includes phenolic resin and 2-ethyl-4-methyl imidazole.

[0014] Further, in the above technical solution, the catalyst is hydrogenated terpineol.

[0015] Further, in the above technical solution, the dispersing agent is sodium dodecyl sulfate.

[0016] Further, in the above technical solution, the internal electrode is mainly made of nickel paste and is formed by a printing coating process, and extends to form a nickel material interface.

[0017] Further, in the above technical solution, the end electrode is mainly made of nickel chloride, and is formed by an electroplating process based on the nickel material interface of the internal electrode.

[0018] Further, in the above technical solution, the low-temperature curing process temperature is 120-130℃, and the time is 20-30 minutes.

[0019] Further, in the above technical solution, the external nickel layer and the soldering tin layer are formed layer by layer by a coating process.

[0020] Compared with the prior art, the present application has the following advantages: 1. The existing multilayer ceramic capacitor (MLCC) often uses copper material or silver material to form the end electrode by high-temperature sintering process, while the structure and process of the present application use nickel material to form the end electrode by electroplating, which belongs to low-temperature process.

[0021] Specifically, the traditional high-temperature sintering process uses copper or silver material, which is more expensive and has differences with the internal electrode nickel material, which is prone to interface peeling under high temperature difference and high impact. The process of forming the end electrode by electroplating nickel material is low in cost, environmentally friendly, and well integrated with the internal electrode nickel material, with higher density, effectively resisting the interface peeling problem caused by high temperature difference and high impact.

[0022] 2. The present application designs a soft terminal layer using silver paste as the main material, which plays the role of elastic layer, effectively absorbs external stress, avoids the impact force of the circuit board from touching the rigid ceramic body of the MLCC, and makes the MLCC device have strong bending and impact resistance.

[0023] Based on the above reasons, the present application can be widely popularized in the field of automotive multilayer ceramic capacitor (MLCC) and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description: Figure 1 It is a structural schematic diagram of the present application; Figure 2 It is a soft terminal silver paste mixing process flow chart of the present application; In the figure, 1. Internal electrode 2. End electrode 3. Laminated ceramic 4. Soft terminal layer 5. External nickel layer 6. Soldering tin layer. DETAILED DESCRIPTION

[0025] In order to make the embodiments in the present application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to explain the present application in detail. Obviously, the described embodiments are part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0026] Example 1 Figure 1 This is a schematic diagram of the structure of the present invention, as shown below. Figure 1 As shown, an automotive-grade soft-terminal multilayer ceramic capacitor based on electroplated end electrodes is described. It includes a stacked ceramic structure, which consists of multiple stacked ceramic layers and an internal electrode layer; The internal electrode layer is made of nickel and extends alternately to both ends of the laminated ceramic to form an internal electrode nickel material interface. The laminated ceramic has end electrodes at both ends, which are made of nickel and formed on the basis of the nickel material interface of the inner electrode; each electrode in the inner electrode layer is connected to only one end of the end electrodes. The outer side of the terminal electrode is also provided with a soft terminal layer, an outer nickel layer and a solder flux layer in sequence; The soft terminal layer is located between the terminal electrode and the outer nickel layer. The soft terminal silver paste, which is formed by mixing silver powder, resin, curing agent, dispersant, catalyst and organic solvent, is placed on the surface of the terminal electrode and cured by a low-temperature curing process. The low-temperature curing process has a temperature of 120°C and a time of 30 minutes.

[0027] The outer nickel layer and solder layer completely cover the surface of the flexible terminal layer.

[0028] The raw materials for the flexible terminal layer are formulated in the following mass ratios: 68 parts silver powder; 14 parts liquid resin; 1 part curing agent; 1.3 parts dispersant; 0.7 parts catalyst; and the mass ratio of resin to organic solvent in the liquid resin is 2:8.

[0029] Method for preparing the soft-terminal silver paste used in the soft-terminal layer: S1. Preparation of liquid resin: The epoxy resins were added separately to the organic solvent and mixed and stirred. The epoxy resins included alicyclic epoxy resin, bisphenol A epoxy resin, and modified epoxy resin. The weight ratio of the three resins was 2:4:4. The mass ratio of the total epoxy resin to the organic solvent was 2:8. The stirring time was 2 to 3 hours, the stirring speed was 800 to 1000 rpm, and the stirring temperature was 60 to 80℃. S2, Raw material mixing: The curing agent, catalyst, silver powder, and dispersant are added sequentially to the liquid resin obtained in S1, and stirred at a high speed of 1000~1200 rpm for 2~5 minutes to form a soft-end silver paste. The curing agent is phenolic resin and 2-ethyl-4-methylimidazole; the catalyst is hydrogenated terpineol; and the dispersant is sodium dodecyl sulfate.

[0030] S3, Viscosity Test: After electroplating the end electrodes (structure 3), the test semi-finished device is dipped into a small sample of the soft-end silver paste obtained in S2, dried and cured for observation.

[0031] S4, viscosity adjustment: Based on the observation of S3, add an appropriate amount of organic solvent to the soft terminal silver paste obtained in S2, high-speed stirring at 1000-1200 rpm for 2-5 min, repeat S3 step until the desired physical appearance is obtained, and the best viscosity is in the range of 25 pa.s-28 pa.s at 10 rpm.

[0032] The internal electrode is mainly made of nickel paste and formed by printing coating process, and extends to form a nickel material interface.

[0033] The end electrode is mainly made of nickel chloride, and is formed by electroplating process based on the nickel material interface of the internal electrode.

[0034] The outer nickel layer and the soldering tin layer are formed layer by layer by coating process.

[0035] The performance data of the above capacitor are as follows:

[0036] Example 2 A vehicle gauge soft terminal multilayer ceramic capacitor structure based on electroplated end electrode includes: Structure one, laminated ceramic; Structure two, internal electrode; Structure three, end electrode; Structure four, soft terminal layer; Structure five, outer nickel layer; Structure six, soldering tin layer.

[0037] Further, the internal electrode is mainly made of nickel paste and formed by printing coating process, and extends to both ends of the laminated ceramic to form a nickel material interface.

[0038] Further, the end electrode is mainly made of nickel chloride and is formed by electroplating process based on the nickel material interface of the internal electrode.

[0039] Further, the soft terminal layer is made of silver powder, resin, curing agent, dispersing agent, catalyst and organic solvent as raw materials, and forms a soft terminal silver paste after mixing processing, and is dipped on the surface of the end electrode and formed by low temperature curing process.

[0040] Specifically, the raw materials of the soft terminal layer are matched in the following mass parts: Silver powder 60-75 parts; Liquid resin 10-15 parts; Curing agent 0.1-2 parts; Dispersing agent 0.1-2 parts; Catalyst 0.1-2 parts; and 4-10 parts of organic solvent.

[0041] Further, Figure 2 The soft terminal silver paste mixing process flow chart of the present application is shown in the following detailed steps: S1, resin dissolving: According to different product requirements, 2-3 kinds of solid resins are added to the organic solvent for mixing and stirring. The mass ratio of solid resin to organic solvent is 2:8, the stirring time is 2-3 hours, the stirring speed is 800-1000 rpm, and the stirring temperature is 60-80℃. S2, raw material mixing: The curing agent, catalyst, silver powder, and dispersing agent are sequentially added to the liquid resin obtained in S1, and high-speed stirring is performed at a speed of 1000-1200 rpm for 2-5 min to form a soft terminal silver paste. S3, viscosity test: After plating the end electrode (structure three), a small amount of sample of the soft terminal silver paste obtained in S2 is dipped, dried, and cured for observation.

[0042] S4, viscosity adjustment: Based on the observation results of S3, an appropriate amount of organic solvent is added to the soft terminal silver paste obtained in S2, and high-speed stirring is performed at a speed of 1000-1200 rpm for 2-5 min. The S3 step is repeated until the desired physical appearance is obtained.

[0043] S5, soft terminal silver paste storage: The soft terminal silver paste obtained in S4 is sealed and packaged for cold storage.

[0044] Further, after the soft terminal layer is completed, an external nickel layer and a soldering tin layer are made.

[0045] Specifically, the external nickel layer and the soldering tin layer are formed layer by layer by a coating process, completely covering the surface of the soft terminal, forming a finished product, a multi-layer ceramic capacitor based on the plating end electrode soft terminal.

[0046] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A plating terminal electrode-based automotive-grade soft terminal multilayer ceramic capacitor, characterized in that: comprising a laminated ceramic structure composed of a plurality of stacked ceramic and internal electrode layers; the internal electrode layer is made of nickel material, and the internal electrode layer alternately extends to both ends of the laminated ceramic to form an internal electrode nickel material interface; both ends of the laminated ceramic are provided with terminal electrodes made of nickel material and formed on the basis of the internal electrode nickel material interface; each layer of internal electrode layer is connected to only one end of the terminal electrode; the terminal electrode is further provided with a soft terminal layer, an external nickel layer and a soldering aid tin layer in sequence; the soft terminal layer is located between the terminal electrode and the external nickel layer, and is formed by placing the soft terminal silver paste formed by mixing silver powder, resin, curing agent, dispersant, catalyst and organic solvent on the surface of the terminal electrode and curing by low-temperature curing process; the external nickel layer and the soldering aid tin layer completely cover the surface of the soft terminal layer; the raw materials of the soft terminal layer are mixed in the following mass ratio: silver powder 60-75 parts; liquid resin 10-15 parts; curing agent 0.1-2 parts; dispersant 0.1-2 parts; catalyst 0.1-2 parts; the mass ratio of resin to organic solvent in liquid resin is 2-3:7-8; the preparation method of the soft terminal silver paste used in the soft terminal layer is as follows: S1, liquid resin preparation: mix and stir the epoxy resin in the organic solvent, the epoxy resin includes alicyclic epoxy resin, bisphenol A epoxy resin and modified epoxy resin, the weight ratio of the three resins is 2-3:3.5-4.5:2.5-3.5, the mass ratio of the total amount of epoxy resin to organic solvent is 2-3:7-8, the stirring time is 2-3 hours, the stirring speed is 800-1000 rpm, and the stirring temperature is 60-80℃; S2, raw material mixing: add the curing agent, catalyst, silver powder and dispersant into the liquid resin obtained in S1, and stir at a high speed of 1000-1200 rpm for 2-5 min to form a soft terminal silver paste; the curing agent includes phenolic resin and 2-ethyl-4-methyl imidazole; the catalyst is hydrogenated terpineol; the dispersant is sodium dodecyl sulfate; the internal electrode is mainly made of nickel paste and formed by printing coating process and forms a nickel material interface; the terminal electrode is mainly made of nickel chloride and formed by electroplating process on the basis of the internal electrode nickel material interface; the low-temperature curing process temperature is 120-130℃, and the time is 20-30 minutes; the external nickel layer and the soldering aid tin layer are formed by coating process layer by layer. ​ ​ ​ ​ ​ ​ 2. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ ​ ​ ​ ​ ​ ​ 3. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ ​ ​ ​ ​ 4. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 5. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 6. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 7. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 8. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 9. The electroplated end electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​ 10. The electroplated terminal electrode based automotive-grade soft termination multilayer ceramic capacitor of claim 1, wherein: ​

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