High-wear-resistance electrically conductive carbon paste for PCB, and preparation method therefor

Abstract

A high-wear-resistance electrically conductive carbon paste for a PCB, and a preparation method therefor. The raw materials of the high-wear-resistance electrically conductive carbon paste comprise the following components, in percentages by weight: 15-30% of electrically conductive carbon black, 15-30% of flake graphite, 1-5% of a dispersant, 0.1-1% of a defoaming agent, 1-5% of a cross-linking agent, 20-30% of a polymer resin and 30-40% of an organic solvent. The high-wear-resistance electrically conductive carbon paste for a PCB is prepared by means of the steps of material preparation, formulation of an organic carrier, formulation of an electrically conductive carbon paste, production of an electrically conductive carbon paste, etc. The prepared electrically conductive carbon paste for a PCB solves the technical problems of printability, adhesive force, electrical conductivity, acetone resistance, wear resistance, etc., and various technical indexes of the product reach the level of similar foreign products.

Description

A high wear-resistant conductive carbon paste for PCB boards and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of conductive carbon paste, and in particular to a highly wear-resistant conductive carbon paste for PCB boards and a preparation method thereof. Background Art

[0002] With the rapid development of the electronic circuit industry, my country's printed circuit board (PCB) industry is gradually developing towards high-end, mature, and diversified development, gradually extending to the top of the industry market. With the continuous emergence of various new electronic products, such as mobile phones, computers, mobile Internet, Internet of Things, big data, cloud computing, artificial intelligence, and unmanned driving, the PCB industry will continue to develop rapidly, and the performance requirements of products will become increasingly higher.

[0003] PCBs are the core components of various electronic products and the foundation of most electronic products. These core components are available in a wide variety of configurations, allowing them to provide a wide variety of functions. PCBs are the main functional center of most electronic products in the modern world, connecting various components to each other through a series of related circuits.

[0004] Among many electronic products, carbon film potentiometers are the most widely used. The resistor body is made of conductive carbon black, flake graphite, and other materials, while the terminals are made of conductive silver powder, conductive graphite, ultrafine glass powder, and molybdenum disulfide. The resistor is then screen-printed onto a PCB substrate and heated at 170-200°C for 7-20 minutes. The lifespan of a carbon film potentiometer is generally around 20,000 cycles. As the quality requirements for electronic products continue to rise, especially regarding technical parameters such as product lifespan and weight, the wear resistance testing of conductive carbon paste for PCBs has also reached a high threshold, such as 1 million cycles. Currently, most domestic electronics factories use carbon paste from foreign manufacturers, such as Fujikura of Japan, which is relatively expensive.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a highly wear-resistant conductive carbon paste for PCB boards and a preparation method thereof.

[0007] The object of the present invention can be achieved by the following technical solution: a highly wear-resistant conductive carbon paste for PCB boards, wherein the raw materials adopt the following components and their weight percentage contents: 15-30% conductive carbon black; 15-30% flake graphite; 1-5% dispersant; 0.1-1% defoaming agent; 1-5% crosslinking agent; 16-30% polymer resin; and 25-40% organic solvent.

[0008] Preferably, the PCB board uses a highly wear-resistant conductive carbon paste, and the raw materials use the following components and weight percentages: conductive carbon black 15-30%; flake graphite 15-30%; dispersant 1-5%; defoaming agent 0.1-1%; cross-linking agent 1-5%; polymer resin 20-30%; and organic solvent 30-40%.

[0009] Preferably, the conductive carbon black particles have a size of 20-50 nm and a specific surface area of ​​200-300 m 2 / g, density is 0.2-0.5g / cm 3 .

[0010] Preferably, the flake graphite particles have a size of 10-15 nm, an ash content of <0.06%, and a specific surface area of ​​10-20 m 2 / g, density is 0.05-0.15g / cm 3 .

[0011] Preferably, the dispersant comprises an anionic wetting and dispersing agent.

[0012] Preferably, the defoaming agent comprises a polymer defoaming agent and does not contain silicone.

[0013] Preferably, the cross-linking agent comprises an amino resin.

[0014] Further preferably, the cross-linking agent comprises a small molecule amino resin.

[0015] Preferably, the polymer resin comprises one or more of phenolic resin, phenolic epoxy resin, and epoxy resin.

[0016] Preferably, the organic solvent comprises one or more of diethylene glycol ethyl ether, diethylene glycol butyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether, and propylene glycol methyl ether propionate.

[0017] A method for preparing the above-mentioned highly wear-resistant conductive carbon paste for PCB boards comprises the following steps:

[0018] (1) Preparation of organic carrier: Add polymer resin to solvent, heat and dissolve, then filter and remove impurities to obtain organic carrier;

[0019] (2) Preparation of conductive carbon slurry: After the conductive carbon black, flake graphite, dispersant, crosslinking agent and organic carrier are fully mixed, high-speed dispersion is performed to obtain a uniform black slurry;

[0020] (3) Production of conductive carbon paste: The black paste is ground in a three-roll mill, first controlling the fineness to be below 10 μm, then controlling the fineness to be below 5 μm, and the viscosity to be 50-100 Pa·S. Finally, a defoaming agent is added and stirred to disperse uniformly, thereby preparing the highly wear-resistant conductive carbon paste for PCB boards.

[0021] Preferably, the filtering and impurity removal in step (1) is carried out using a mesh of 300-400 mesh.

[0022] Preferably, in step (1), the temperature is heated to 60-80° C. and the temperature is kept constant until the polymer resin is completely dissolved.

[0023] Preferably, the high-speed dispersion rate in step (2) is 1800-2200 r / min.

[0024] Preferably, in step (3), the fineness of the conductive carbon paste is first controlled to be below 10 μm by roller fine adjustment, and then the fineness of the conductive carbon paste is further controlled to be below 5 μm by a sand grinder.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention enhances the adhesion between the conductive carbon paste and the PCB by selecting a polymer resin and a crosslinking agent. The combination of conductive carbon black and flake graphite adjusts the conductive carbon paste's resistance range, reduces the paste's friction coefficient, and improves the product's wear resistance. The selection of dispersants and defoamers optimizes the paste's printing processability and product stability. After curing at a moderate temperature, the organic solvent in the conductive carbon paste evaporates upon heating, and the polymer resin and crosslinking agent undergo a chemical crosslinking reaction upon heating, adhering the conductive carbon black and flake graphite to the PCB surface, creating a circuit with a specific resistance value. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operating processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] (1) Prepare 1 kg of material according to the following composition and mass:

[0030] The conductive carbon black used has a particle size of 30 nm and a specific surface area of ​​254 m 2 / g, density is 0.256g / cm 3 .

[0031] The flake graphite used has a particle size of 12.7 nm, an ash content of 0.05%, and a specific surface area of ​​12 m 2 / g, density is 0.10g / cm 3 .

[0032] The dispersant used comprised the anionic wetting and dispersing agent BYK163.

[0033] The defoamer used is the polymeric defoamer BYK052N, which does not contain silicone.

[0034] The crosslinking agent used comprises an amino resin.

[0035] The polymer resin used includes phenolic resin.

[0036] The organic solvent used included diethylene glycol ethyl ether.

[0037] (2) Preparation of organic carrier: Phenolic resin and diethylene glycol ethyl ether were weighed, and then heated to 70°C and kept at a constant temperature. After the phenolic resin was completely dissolved, it was filtered on a 400-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0038] (3) Preparation of conductive carbon slurry: Conductive carbon black, flake graphite, dispersant, and crosslinking agent are weighed and fully mixed with the organic carrier in a mixer, and then dispersed at high speed using a high-speed disperser to obtain a uniform black slurry;

[0039] (4) Production of conductive carbon paste: The above-mentioned paste is ground in a three-roll mill, and the fineness of the conductive carbon paste is controlled to 9 μm by fine adjustment of the roller. The fineness of the conductive carbon paste is further controlled to 4 μm by a sand mill, and the viscosity is 80 Pa·S. Finally, a weighed defoaming agent is added and stirred to disperse evenly, thereby preparing a highly wear-resistant conductive carbon paste for PCB boards.

[0040] Example 2

[0041] (1) Prepare 1 kg of material according to the following composition and mass:

[0042] The conductive carbon black used has a particle size of 30 nm and a specific surface area of ​​254 m 2 / g, density is 0.256g / cm 3 .

[0043] The flake graphite used has a particle size of 12.7 nm, an ash content of 0.05%, and a specific surface area of ​​12 m 2 / g, density is 0.10g / cm 3 .

[0044] The dispersant used comprised the anionic wetting and dispersing agent BYK163.

[0045] The defoamer used is the polymeric defoamer BYK052N, which does not contain silicone.

[0046] The crosslinking agent used comprises an amino resin.

[0047] The polymer resin used includes novolac epoxy resin.

[0048] The organic solvents used include diethylene glycol ethyl ether and diethylene glycol butyl ether.

[0049] (2) Preparation of organic vehicle: Weigh phenolic epoxy resin, diethylene glycol ethyl ether and diethylene glycol butyl ether, then heat them to 70°C and keep the temperature constant. After the phenolic epoxy resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic vehicle;

[0050] (3) Preparation of conductive carbon slurry: Conductive carbon black, flake graphite, dispersant, and crosslinking agent are weighed and fully mixed with the organic carrier in a mixer, and then dispersed at high speed using a high-speed disperser to obtain a uniform black slurry;

[0051] (4) Production of conductive carbon paste: The above-mentioned paste is ground in a three-roll mill, and the fineness of the conductive carbon paste is controlled to 7 μm by fine adjustment of the roller. The fineness of the conductive carbon paste is further controlled to 2 μm by a sand mill, and the viscosity is 60 Pa·S. Finally, a weighed defoaming agent is added and stirred to disperse evenly, thereby preparing a highly wear-resistant conductive carbon paste for PCB boards.

[0052] Example 3

[0053] (1) Prepare 1 kg of material according to the following composition and mass:

[0054] The conductive carbon black used has a particle size of 30 nm and a specific surface area of ​​254 m 2 / g, density is 0.256g / cm 3 .

[0055] The flake graphite used has a particle size of 12.7 nm, an ash content of 0.05%, and a specific surface area of ​​12 m 2 / g, density is 0.10g / cm 3 .

[0056] The dispersant used comprised the anionic wetting and dispersing agent BYK163.

[0057] The defoamer used is the polymeric defoamer BYK052N, which does not contain silicone.

[0058] The crosslinking agent used comprises an amino resin.

[0059] The polymer resins used include phenolic resin and epoxy resin.

[0060] The organic solvent used included diethylene glycol butyl ether.

[0061] (2) Preparation of organic vehicle: Phenolic resin, epoxy resin and diethylene glycol butyl ether were weighed, and then heated to 70°C and kept at a constant temperature. After the phenolic resin was completely dissolved, it was filtered on a 400-mesh mesh to remove impurities, thereby obtaining an organic vehicle;

[0062] (3) Preparation of conductive carbon slurry: Conductive carbon black, flake graphite, dispersant, and crosslinking agent are weighed and fully mixed with the organic carrier in a mixer, and then dispersed at high speed using a high-speed disperser to obtain a uniform black slurry;

[0063] (4) Production of conductive carbon paste: The above-mentioned paste is ground in a three-roll mill, and the fineness of the conductive carbon paste is controlled to 9 μm by fine adjustment of the roller. The fineness of the conductive carbon paste is further controlled to 3 μm by a sand mill, and the viscosity is 100 Pa·S. Finally, a weighed defoaming agent is added and stirred to disperse evenly, thereby preparing a highly wear-resistant conductive carbon paste for PCB boards.

[0064] The test results of adhesion, conductivity, acetone resistance, wear resistance and other related properties are shown in the following table:

[0065] The conductive carbon paste for PCB boards prepared by the present invention solves technical problems such as printability, adhesion, conductivity, acetone resistance, and wear resistance, and various technical indicators of the product reach the level of similar foreign products.

[0066] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A highly wear-resistant conductive carbon paste for PCB boards, characterized in that: The raw materials use the following components and weight percentage contents: 15-30% of conductive carbon black; 15-30% of flake graphite; 1-5% of dispersant; 0.1-1% of defoamer; 1-5% of cross-linking agent; 16-30% of polymer resin; and 25-40% of organic solvent.

2. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The conductive carbon black particles have a size of 20-50 nm and a specific surface area of ​​200-300 m 2 / g, density is 0.2-0.5g / cm 3 .

3. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The flake graphite particles have a size of 10-15 nm, an ash content of <0.06%, and a specific surface area of ​​10-20 m 2 / g, density is 0.05-0.15g / cm 3 .

4. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The dispersant comprises an anionic wetting and dispersing agent.

5. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The defoamer comprises a polymer defoamer and does not contain silicone.

6. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The crosslinking agent comprises an amino resin.

7. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The polymer resin includes one or more of phenolic resin, phenolic epoxy resin and epoxy resin.

8. The highly wear-resistant conductive carbon paste for PCB board according to claim 1, characterized in that: The organic solvent comprises one or more of diethylene glycol ethyl ether, diethylene glycol butyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether, and propylene glycol methyl ether propionate.

9. A method for preparing a highly wear-resistant conductive carbon paste for a PCB board according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of organic carrier: adding polymer resin to solvent, heating and dissolving, filtering and removing impurities to obtain organic carrier; (2) Preparation of conductive carbon slurry: After the conductive carbon black, flake graphite, dispersant, crosslinking agent and organic carrier are fully mixed, they are dispersed at high speed to obtain a uniform black slurry; (3) Production of conductive carbon slurry: The black slurry is ground in a three-roll mill, first controlling the fineness to be less than 10 μm, then controlling the fineness to be less than 5 μm, and the viscosity to be 50-100 Pa·S, and finally adding a defoaming agent to stir and disperse evenly. The highly wear-resistant conductive carbon paste for the PCB board is prepared.

10. The method for preparing highly wear-resistant conductive carbon paste for PCB board according to claim 9, characterized in that: The filtering and impurity removal in step (1) is carried out using a mesh of 300-400 mesh; In step (3), the fineness of the conductive carbon paste is first controlled to be less than 10 μm by roller fine adjustment, and then the fineness of the conductive carbon paste is further controlled to be less than 5 μm by a sand mill.

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