Preparation Method of Electronic Paste, Electronic Paste and Application

Abstract

The present invention relates to a preparation method of an electronic paste, an electronic paste and an application, belonging to the technical field of electronic pastes. A preparation method of an electronic paste includes the following steps: uniformly mixing silver powder, a first resin and a first solvent to obtain a first premix; uniformly mixing silver-coated copper powder, a dispersant, a second resin and a second solvent to obtain a second premix; respectively grinding the first premix and the second premix to obtain a first paste and a second paste; uniformly mixing the first paste and the second paste to obtain the electronic paste. The present invention can maximize the conductivity of the silver-coated copper powder, reduce or avoid the loss of electrical properties caused by the oxidation of the silver-coated copper powder, and thereby improve the conductivity of the electronic paste.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic pastes, and particularly relates to a preparation method of an electronic paste, an electronic paste and an application thereof. Background Art

[0002] In recent years, with the continuous development of the printed electronics industry, the market of electronic pastes has increasingly attracted people's attention. Since silver has a relatively high conductivity and is not easily oxidized, most of the current electronic pastes on the market are silver pastes. However, silver pastes have problems such as high price and easy occurrence of electromigration failure. Therefore, people have turned their attention to copper, which has a conductivity similar to that of silver. Relatively speaking, copper has a lower price and is second only to silver in terms of electrical properties. However, copper is not resistant to high temperatures and is extremely easy to oxidize in the air, reducing its conductivity and thus reducing the conductivity of copper paste. Silver-coated copper paste combines the advantages of both, which can not only solve the electromigration problem of silver but also reduce costs and improve the oxidation problem of copper. Therefore, silver-coated copper powder is an ideal alternative material for silver powder.

[0003] In related technologies, for electronic pastes containing silver-coated copper powder, the industry mainly focuses on improving and optimizing the preparation of silver-coated copper powder, while ignoring the improvement of the preparation method of electronic pastes containing silver-coated copper powder. It is only to mix various raw materials such as silver-coated copper powder together for preparation, which fails to effectively exert the conductivity of silver-coated copper powder and reduces the conductivity of the electronic paste. Therefore, it is necessary to start from the application perspective of silver-coated copper powder and optimize the preparation method of the electronic paste to maximize its good conductivity and improve the conductivity of the electronic paste. Summary of the Invention

[0004] In view of the above problems, the present invention aims to solve at least one of the technical problems in the related technologies to some extent. For this reason, the present invention provides a preparation method of an electronic paste, an electronic paste and an application thereof, which can maximize the conductivity of silver-coated copper powder, reduce or avoid the loss of electrical properties caused by the oxidation of silver-coated copper powder, and thus improve the conductivity of the electronic paste.

[0005] As an aspect of the present invention, it relates to a preparation method of an electronic paste, including the following steps:

[0006] Mix silver powder, a first resin and a first solvent evenly to obtain a first premix;

[0007] Mix silver-coated copper powder, a dispersant, a second resin and a second solvent evenly to obtain a second premix;

[0008] Grind the first premix and the second premix respectively to obtain a first paste and a second paste;

[0009] Mix the first slurry and the second slurry evenly to obtain the electronic slurry.

[0010] In addition, according to the method for preparing the electronic slurry of the invention, the following additional technical features may also be included:

[0011] In some embodiments of the present application, the step of mixing the silver powder, the first resin and the first solvent evenly specifically includes: adding the first resin and the first solvent into a container, stirring evenly at a first rotation speed, then adding the silver powder into the container, and stirring evenly at a second rotation speed.

[0012] Preferably, the first rotation speed and the second rotation speed are respectively 500 - 3000 revolutions per minute; preferably, the stirring time at the second rotation speed is 10 - 30 min.

[0013] In some embodiments of the present application, the step of mixing the silver-coated copper powder, the dispersant, the second resin and the second solvent evenly specifically includes: adding the second resin, the first solvent and the dispersant into a container, stirring evenly at a third rotation speed, then adding the silver-coated copper powder into the container, and stirring evenly at a fourth rotation speed.

[0014] Preferably, the third rotation speed and the fourth rotation speed are respectively 500 - 3000 revolutions per minute; preferably, the stirring time at the fourth rotation speed is 10 - 30 min.

[0015] In some embodiments of the present application, the dispersant is an acidic dispersant.

[0016] In some embodiments of the present application, the step of respectively grinding the first premix and the second premix specifically includes: placing the first premix in a three-roll mill for grinding to form a slurry; placing the second premix in a three-roll mill for grinding to form a slurry.

[0017] In some embodiments of the present application, the step of placing the first premix in a three-roll mill for grinding includes: performing three-roll grinding according to the standard process of three-roll grinding; and / or, grinding the first premix in a three-roll mill until the fineness of the material is less than or equal to 10 μm to form a slurry.

[0018] In some embodiments of the present application, the step of placing the second premix in a three-roll mill for grinding includes: the distance between the first roll and the second roll in the three-roll mill is 6 - 10 times the particle size of the silver-coated copper powder, and the distance between the second roll and the third roll is 1.5 - 4 times the particle size of the silver-coated copper powder.

[0019] In some embodiments of the present application, an auxiliary agent is added during the preparation of the first premix; alternatively, an auxiliary agent is added during the preparation of the second premix; alternatively, a part of the auxiliary agent (which is more easily dispersible) is added during the preparation of the first premix, and the remaining part of the auxiliary agent is added during the preparation of the second premix.

[0020] In some embodiments of the present application, after the first slurry and the second slurry are mixed evenly, a step of vacuum centrifugal defoaming is further included.

[0021] In some embodiments of the present application, the mass ratio of the first resin to the second resin is (20-98):(2-80); preferably, the mass ratio of the first solvent to the second solvent is (20-98):(2-80).

[0022] As another aspect of the present invention, an electronic paste is provided, and the electronic paste is prepared by the preparation method of the electronic paste as described above.

[0023] In some embodiments of the present application, the electronic paste includes silver powder, silver-coated copper powder, resin, solvent, and dispersant. Among them, the resin is composed of a first resin and a second resin, and the solvent is composed of a first solvent and a second solvent;

[0024] In some embodiments of the present application, the dispersant is an acidic dispersant; preferably, the acid value of the acidic dispersant is (100-200) mg KOH / g.

[0025] In some embodiments of the present application, the electronic paste further includes an auxiliary agent, and the auxiliary agent includes at least one of a leveling agent, a thickening agent, or a rheological auxiliary agent.

[0026] As still another aspect of the present invention, an application of the preparation method of the electronic paste as described above in the preparation of electronic devices is provided.

[0027] Compared with the prior art, the technical solution of the present application has at least the following beneficial effects:

[0028] In the preparation method of the electronic paste provided by the present application, silver powder, the first resin, and the first solvent are mixed evenly to obtain a first premix, and silver-coated copper powder, a dispersant, the second resin, and the second solvent are mixed evenly to obtain a second premix; by mixing silver powder and silver-coated copper powder with solvents and resins respectively, and adding a dispersant in the step of dispersing silver-coated copper powder in the organic component, the conductivity of the prepared electronic paste can be improved, and its conductivity can be increased by at least more than 20%.

[0029] The preparation method of the electronic paste provided by this application uses silver-coated copper powder and silver powder as conductive components, which can reduce costs and ensure the conductivity of the silver-coated copper powder to the greatest extent, reducing or avoiding the loss of electrical properties caused by the oxidation of the silver-coated copper powder. The dispersant added to this electronic paste can play a positive and effective role in simplifying the grinding process, improving the grinding efficiency, ensuring fineness, and ensuring the conductivity of the conductive components in the electronic paste.

[0030] The method of the present invention is simple and easy to implement, easy to operate, and easy to achieve large-scale production. Moreover, the prepared electronic paste has a high conductivity and a low cost, and has good application prospects.

[0031] The additional aspects and advantages of the embodiments of this application will be partially described, shown, or explained through the implementation of the embodiments of this application in the following description. Detailed Embodiments

[0032] The following further elaborates on this application in conjunction with specific embodiments. It should be understood that these embodiments of this application are only used to illustrate this application and not to limit the scope of this application.

[0033] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values or individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0034] In related technologies, when preparing conductive pastes containing silver powder or silver-coated copper powder, only a simple mixing method of organic components, silver powder, and silver-coated copper powder is used to prepare silver paste. The addition sequence of different components such as organic substances and the feeding sequence of different silver powders / silver-coated copper powders are not fully considered. As a result, the organic components and silver powders / silver-coated copper powders are only combined in a single way, and the functions of infiltration, adsorption, lubrication, etc. of the organic components are not fully exerted; the silver powders / silver-coated copper powders are also randomly stacked and filled disorderly. At least based on the above insights into the prior art, the inventors of this application have conducted a large amount of research on the feeding sequence or feeding method of each component when preparing silver paste. It has been found through research that even when using the same silver powders / silver-coated copper powders and organic systems, there are significant differences in the uniformity of the paste, the infiltration effect of the organic components on the silver powders / silver-coated copper powders, the overall dispersion effect of the silver powder, the accumulation of large-particle silver powder, the filling of small-particle silver powder, and the lubrication effect of the organic substances on the surface of the silver powders / silver-coated copper powders when the feeding sequence is different.

[0035] Based on this, from the perspective of the application of silver-coated copper powder, the present invention optimizes the preparation method of the electronic paste to maximize its good conductivity and inhibit its oxidation problem, in order to improve the conductivity of the electronic paste. The description of the specific technical solution is as follows.

[0036] In some embodiments, a method for preparing an electronic paste is provided, including the following steps:

[0037] Mix silver powder, a first resin, and a first solvent evenly to obtain a first premix;

[0038] Mix silver-coated copper powder, a dispersant, a second resin, and a second solvent evenly to obtain a second premix;

[0039] Grind the first premix and the second premix respectively to obtain a first paste and a second paste;

[0040] Mix the first paste and the second paste evenly to obtain the electronic paste.

[0041] The method for preparing the electronic paste provided in this embodiment optimizes the feeding sequence and feeding method of the components. By mixing silver powder and silver-coated copper powder with organic components such as solvents and resins respectively, and adding a dispersant in the step of dispersing the silver-coated copper powder in the organic components, and then grinding the obtained premixes respectively, the functions of the organic components such as infiltration, adsorption, and lubrication can be fully exerted, enhancing the lubrication effect of the organic components on the surfaces of the silver powder and the silver-coated copper powder, improving the grinding quality, and further improving the conductivity of the prepared electronic paste, and its conductivity can be increased by at least 20% or more.

[0042] Furthermore, the inventors of the present application found in a large number of experimental studies that by optimizing the grinding process of the electronic paste, it is helpful to improve the conductivity of the paste. Especially for silver-coated copper powder, due to the limited bonding force between the silver layer and the copper substrate, too small a grinding roll spacing will damage the coating structure. At the same time, adding a dispersant such as an acidic dispersant can enhance the wetting of the powder body, improve the grinding quality, and the conductivity of the electronic paste prepared from the improved silver-coated copper powder can be increased by more than 20%.

[0043] At the same time, the method for preparing the electronic paste provided in this embodiment uses silver-coated copper powder and silver powder as conductive components, which can reduce costs and can maximize the conductivity of the silver-coated copper powder, reducing or avoiding the loss of electrical performance caused by the oxidation of the silver-coated copper powder. Compared with the existing electronic paste without adding a dispersant, in this embodiment, due to the simplification of the grinding process and adding a dispersant to the electronic paste, the grinding efficiency can be improved and the fineness can be ensured. This dispersant is preferably an acidic dispersant. The acidic dispersant can theoretically have better wettability with the fatty acid on the surface of the silver-coated copper and can consume the oxidized copper oxide, appropriately ensuring its conductivity.

[0044] It should be noted that the above-mentioned first resin and second resin can be of the same type or different types; the above-mentioned first solvent and second solvent can be of the same type or different types. Preferably, the first resin and the second resin are of the same type, and the first solvent and the second solvent are of the same type.

[0045] In this embodiment, in the process of preparing the electronic paste, the first premix can be prepared first and then the second premix; or, the second premix can be prepared first and then the first premix; or, the first premix and the second premix can be prepared simultaneously. This embodiment does not limit the preparation sequence of the first premix and the second premix. Correspondingly, the first paste can be prepared first and then the second paste; or, the second paste can be prepared first and then the first paste; or, the first paste and the second paste can be prepared simultaneously. This embodiment does not limit the preparation sequence of the first paste and the second paste.

[0046] In some embodiments, the step of mixing the silver powder, the first resin and the first solvent evenly to obtain the first premix specifically includes: adding the first resin and the first solvent into a container, stirring evenly at a first rotation speed, and then adding the silver powder into the container and stirring evenly at a second rotation speed.

[0047] Optionally, the stirring can be carried out at room temperature. Optionally, the room temperature can be 18 - 30 °C. Optionally, the container can be a stainless steel container.

[0048] In some embodiments, the first rotation speed and the second rotation speed are respectively 500 - 3000 revolutions per minute; preferably, the stirring time at the second rotation speed is 10 - 30 min. Exemplarily, the first rotation speed can be 500 revolutions per minute, 800 revolutions per minute, 1000 revolutions per minute, 1200 revolutions per minute, 1500 revolutions per minute, 2000 revolutions per minute, 3000 revolutions per minute, etc.; the second rotation speed can be 500 revolutions per minute, 800 revolutions per minute, 1000 revolutions per minute, 1200 revolutions per minute, 1500 revolutions per minute, 2000 revolutions per minute, 3000 revolutions per minute, etc.; the stirring time at the second rotation speed can be 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0049] In a specific embodiment, the preparation of the first premix includes: at room temperature, adding the first resin and the first solvent into a stainless steel container according to the formula ratio, stirring evenly at a rotation speed of 1200 revolutions per minute, then adding silver powder into the stainless steel container, and continuing to stir at a rotation speed of 1200 revolutions per minute for 10 - 30 min to obtain the first premix.

[0050] Thus, under the above operating conditions, the first premix is prepared by the above method, which is easy to operate and has high efficiency, and can make the silver powder, the first resin and the first solvent be fully and uniformly mixed.

[0051] In some embodiments, mixing the silver-coated copper powder, the dispersant, the second resin and the second solvent uniformly to obtain the second premix specifically includes: adding the second resin, the first solvent and the dispersant into a container, stirring uniformly at a third rotation speed, and then adding the silver-coated copper powder into the container and stirring uniformly at a fourth rotation speed. Optionally, the stirring can be carried out at room temperature. Optionally, the container can be a stainless steel container.

[0052] In some embodiments, the third rotation speed and the fourth rotation speed are respectively 500 - 3000 revolutions per minute; preferably, the stirring time at the fourth rotation speed is 10 - 30 min. Exemplarily, the third rotation speed can be 500 revolutions per minute, 800 revolutions per minute, 1000 revolutions per minute, 1200 revolutions per minute, 1500 revolutions per minute, 2000 revolutions per minute, 3000 revolutions per minute, etc.; the fourth rotation speed can be 500 revolutions per minute, 800 revolutions per minute, 1000 revolutions per minute, 1200 revolutions per minute, 1500 revolutions per minute, 2000 revolutions per minute, 3000 revolutions per minute, etc.; the stirring time at the fourth rotation speed can be 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0053] In a specific embodiment, preparing the second premix includes: at room temperature, adding the second resin, the second solvent and the dispersant into a stainless steel container according to the formulation ratio, stirring uniformly at a rotation speed of 1200 revolutions per minute, and then adding the silver-coated copper powder into the stainless steel container and continuing to stir at a rotation speed of 1200 revolutions per minute for 10 - 30 min to obtain the second premix.

[0054] Thus, under the above operating conditions, the second premix is prepared by the above method, which is easy to operate and has high efficiency, and can make the silver-coated copper powder, the second resin, the second solvent and the dispersant be fully and uniformly mixed; moreover, by adding the dispersant, the wetting effect of the organic components on the silver-coated copper powder can be enhanced, the oxidation of the silver-coated copper powder can be reduced, which is beneficial to ensuring the conductivity of the silver-coated copper powder.

[0055] In some embodiments, the dispersant is an acidic dispersant. Preferably, the acid value of the acidic dispersant is (100 - 200) mg KOH / g. For example, the acid value of the acidic dispersant can be 100 mg KOH / g, 120 mg KOH / g, 150 mgKOH / g, 160 mg KOH / g, 180 mg KOH / g, 200 mg KOH / g, etc.

[0056] It should be noted that the specific type of the acidic dispersant in the present invention is not limited, as long as the acid value of the acidic dispersant is within the range of (100 - 200) mg KOH / g.

[0057] During the preparation of the electronic paste, adding a dispersant, especially an acidic dispersant, has a positive effect on the grinding process. For example, it can improve the grinding efficiency and ensure the fineness. The acidic dispersant can theoretically have better wettability with the fatty acid on the surface of silver-coated copper and can also consume the oxidized copper oxide to appropriately ensure its conductivity.

[0058] Optionally, an auxiliary agent can also be added during the preparation of the electronic paste. The auxiliary agent can be, for example, a leveling agent, a thickening agent, a rheological auxiliary agent, etc. The addition sequence of the auxiliary agent can be selected and set according to the actual situation. For example, the auxiliary agent is added during the preparation of the first premix, that is, the silver powder, the first resin, the first solvent, and the auxiliary agent are mixed evenly to obtain the first premix. Or, the auxiliary agent is added during the preparation of the second premix, that is, the silver-coated copper powder, the dispersant, the second resin, the second solvent, and the auxiliary agent are mixed evenly to obtain the second premix. Or, a part of the more easily dispersible auxiliary agent is added during the preparation of the first premix, and the remaining part of the auxiliary agent is added during the preparation of the second premix. That is, the silver powder, the first resin, the first solvent, and a part of the more easily dispersible auxiliary agent are mixed evenly to obtain the first premix; the silver-coated copper powder, the dispersant, the second resin, the second solvent, and the remaining part of the auxiliary agent are mixed evenly to obtain the second premix. The ratio of the part of the auxiliary agent in the first premix to the remaining part of the auxiliary agent in the second premix can be adjusted according to actual needs, and this embodiment does not limit this. It should be noted that when adding the auxiliary agent during the preparation process, the easily dispersible auxiliary agent needs to be added first, and then the remaining auxiliary agent.

[0059] In some embodiments, respectively grinding the first premix and the second premix to obtain the first paste and the second paste specifically includes: grinding the first premix to obtain the first paste; grinding the second premix to obtain the second paste. Among them, preparing the first paste includes: placing the first premix in a three-roll mill for grinding to form a paste-like state. Preparing the second paste includes: placing the second premix in a three-roll mill for grinding to form a paste-like state.

[0060] Specifically, preparing the first paste includes: performing three-roll grinding on the first premix according to the standard process of three-roll grinding to obtain the first paste. Optionally, the first premix is placed in a three-roll mill for grinding until the fineness of the material is less than or equal to 10 μm to form a paste-like state, and the first paste is obtained.

[0061] According to this embodiment, when preparing the first slurry, a three-roll grinder is used for grinding, and the first premix is subjected to three-roll grinding according to the standard process, which refers to the conventional standard process of three-roll grinding. For example, the spacing between the rollers in the three-roll grinder is standard, and the operation method is standard and conventional. This embodiment does not make any limitations in this regard.

[0062] In some embodiments, preparing the second slurry includes: subjecting the second premix to three-roll grinding with the roll spacing being 6 to 10 times the particle size of the silver-coated copper powder and 1.5 to 4 times the particle size of the silver-coated copper powder, respectively, to obtain the second slurry. That is, the three-roll grinder includes a first roll, a second roll, and a third roll arranged at intervals. The spacing between the first roll and the second roll is 6 to 10 times the particle size of the silver-coated copper powder, and the spacing between the second roll and the third roll is 1.5 to 4 times the particle size of the silver-coated copper powder. Exemplarily, the spacing between the first roll and the second roll can be 6 times, 7 times, 8 times, 9 times, 10 times, etc. of the particle size of the silver-coated copper powder; the spacing between the second roll and the third roll is 1.5 times, 2 times, 2.5 times, 3 times, 3.5 times, 4 times, etc. of the particle size of the silver-coated copper powder.

[0063] In this embodiment, by optimizing the roll spacing in the three-roll grinder, the structure of the silver-coated copper powder can be ensured, and the damage to the silver-coated copper powder can be reduced or avoided. Specifically, the inventors of this application found in a large number of experiments that by optimizing the grinding process of the electronic slurry, it helps to improve the conductivity of the slurry. Especially for the silver-coated copper powder, due to the limited bonding force between the silver layer and the copper substrate, too small a grinding roll spacing will damage the coating structure. At the same time, adding an acidic dispersant to enhance the wetting of the powder can improve the grinding quality. The conductivity of the electronic slurry prepared with the improved silver-coated copper powder can be increased by more than 20%.

[0064] In some embodiments, after mixing the first slurry and the second slurry evenly, it further includes a step of vacuum centrifugal defoaming.

[0065] During the preparation of the electronic slurry, the first slurry and the second slurry are mixed evenly, and then vacuum centrifugal defoaming is carried out to obtain the electronic slurry.

[0066] It should be noted that this embodiment does not make any limitations on the specific operation method or conditions of vacuum centrifugal defoaming, and reference can be made to the prior art, which will not be elaborated here.

[0067] In some embodiments, the mass ratio of the first resin to the second resin is (20 - 98):(2 - 80). In some embodiments, the mass ratio of the first resin to the second resin is (30 - 80):(20 - 70). Exemplarily, the mass ratio of the first resin to the second resin can be 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 90:10, 98:2, etc.

[0068] In some embodiments, the mass ratio of the first solvent to the second solvent is (20-98):(2-80). In some embodiments, the mass ratio of the first solvent to the second solvent is (30-80):(20-70). Exemplarily, the mass ratio of the first solvent to the second solvent can be 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 90:10, 98:2, etc.

[0069] In this embodiment, the ratio of the first resin to the second resin and the ratio of the first solvent to the second solvent can be selected and set according to actual conditions, as long as the sum of the masses of the first resin and the second resin and the sum of the masses of the first solvent and the second solvent are within the specified range, that is, as long as the total resin amount and the total solvent amount contained in the electronic paste are within a suitable range. This embodiment does not limit this.

[0070] In some specific embodiments, the method for preparing the electronic paste includes the following steps:

[0071] At room temperature, according to the formulation ratio, add the first resin and the first solvent to a stainless steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver powder to the stainless steel container, and continue to stir at a speed of 1200 revolutions per minute for 10-30 min to obtain a first premix.

[0072] At room temperature, according to the formulation ratio, add the second resin, the second solvent and a dispersant to a stainless steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver-coated copper powder to the stainless steel container, and continue to stir at a speed of 1200 revolutions per minute for 10-30 min to obtain a second premix. Among them, the dispersant is an acidic dispersant, and the acid value of the acidic dispersant is (100-200) mg KOH / g.

[0073] Optionally, additives are added during the preparation of the first premix and / or the second premix.

[0074] Perform three-roll grinding on the first premix according to the standard process of three-roll grinding to obtain a first paste.

[0075] Perform three-roll grinding on the second premix at roll spacings of 6-10 times the particle size of the silver-coated copper powder and 1.5-4 times the particle size of the silver-coated copper powder to obtain a second paste.

[0076] Mix the uniformly ground first paste and second paste evenly, and then perform vacuum centrifugal defoaming to obtain the electronic paste.

[0077] Based on the same inventive concept, in some embodiments, an electronic paste is further provided, and the electronic paste is prepared by the preparation method of the electronic paste as described above.

[0078] It should be understood that the electronic paste of the present application and the preparation method of the foregoing electronic paste are based on the same inventive concept. This electronic paste is prepared by the above method, and thus has at least all the features and advantages of the preparation method of the electronic paste, which will not be elaborated here.

[0079] In some embodiments, the electronic paste includes silver powder, silver-coated copper powder, resin, solvent, and dispersant. Among them, the resin is composed of a first resin and a second resin, and the solvent is composed of a first solvent and a second solvent. Optionally, the mass ratio of the first resin to the second resin is (20-98):(2-80). Optionally, the mass ratio of the first solvent to the second solvent is (20-98):(2-80).

[0080] In some embodiments, the dispersant is an acidic dispersant; preferably, the acid value of the acidic dispersant is (100-200) mg KOH / g.

[0081] In some embodiments, the electronic paste further includes additives, and the additives include at least one of a leveling agent, a thickening agent, or a rheological aid. In this electronic paste, according to actual needs, additives can be added or not added.

[0082] It should be noted that there are no restrictive requirements on the specific types or sources of the various raw materials in the electronic paste in this embodiment, such as silver powder, silver-coated copper powder, resin, solvent, dispersant, additives, etc. Those skilled in the art can flexibly select according to actual needs as long as the purpose of the present invention is not restricted. For example, various raw materials well-known to those skilled in the art can be used, their commercially available products can be used, or they can be prepared by themselves.

[0083] Optionally, this electronic paste includes the following raw materials in mass percentages: 30-70 wt% of silver-coated copper powder, 10-30 wt% of silver powder, 0.01-3 wt% of dispersant, 5-10 wt% of thermoplastic resin, 10-50 wt% of solvent, 0-10 wt% of additives, etc. Further, this electronic paste includes the following raw materials in mass percentages: 35-65 wt% of silver-coated copper powder, 15-25 wt% of silver powder, 0.05-2.5 wt% of dispersant, 6-9 wt% of thermoplastic resin, 15-20 wt% of solvent, 0.1-5 wt% of additives, etc.

[0084] Optionally, the silver-coated copper powder is one or more of flaky silver-coated copper powder, spherical silver-coated copper powder, and dendritic silver-coated copper powder; the silver powder is one or more of flaky silver powder, spherical silver powder, and dendritic silver powder. Optionally, the mass content of silver in the silver-coated copper powder is between 10% and 50%. Optionally, the particle size distributions of the silver-coated copper powder and the silver powder are D50: 6.0 - 10.0 μm, tap density: 0.5 - 2.5 g / cm 3 , bulk density: 1.0 - 3.5 g / cm 3 .

[0085] Optionally, the thermoplastic resin is at least one of polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, polyacrylate, EVA resin, PVB resin, polybutadiene, and polyester resin. Optionally, the solvent is at least one of cyclohexanone, isophorone, ethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, dimethyl adipate, diethyl adipate, DBE, dibasic acid ester, diol ester, N-methylpyrrolidone, or terpineol. Optionally, the additives include a leveling agent, a thickening agent, and other rheological additives, etc.

[0086] In some embodiments, there is provided a method for preparing the electronic paste as described above or an application of the electronic paste in the preparation of electronic devices.

[0087] The electronic devices described in the present invention can be various well-known electronic devices in the art. Considering the functions of the electronic paste and its preparation method of the present invention, preferably, the electronic devices can include RFID, membrane switches, electrode wires, etc.

[0088] The method for preparing the electronic paste and the electronic paste provided in the embodiments of the present invention can be widely applied to fields such as RFID, membrane switches, electrode wires, etc., and have good application effects.

[0089] It should be understood that the electronic device includes the electronic paste prepared by the method for preparing the electronic paste provided in this embodiment, and thus has at least all the features and advantages of the electronic paste and its preparation method, which will not be elaborated here.

[0090] The following further illustrates the method for preparing the electronic paste and the electronic paste of the present application with specific examples. Those skilled in the art will understand that only some examples are described in the present invention, and any other suitable specific examples are within the scope of the present invention.

[0091] Example 1

[0092] 1. An electronic paste, comprising raw materials in the following mass percentages: 50 wt% of silver-coated copper powder (silver content 25%), 12 wt% of silver powder, 0.1 wt% of acidic dispersant, 7 wt% of thermoplastic polyurethane (or thermoplastic PVB resin, etc.), and 30.9 wt% of isophorone (or terpineol, etc.). Among them, the acid value of the acidic dispersant is 160 mg KOH / g.

[0093] 2. A method for preparing an electronic paste, comprising the following steps:

[0094] S1. At room temperature, according to the formula ratio, add thermoplastic polyurethane and isophorone into a stainless-steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver powder into the stainless-steel container, and continue to stir at a speed of 1200 revolutions per minute for 20 min to obtain a first premix.

[0095] S2. According to the formula ratio, add thermoplastic polyurethane, isophorone and acidic dispersant into a stainless-steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver-coated copper powder into the stainless-steel container, and continue to stir at a speed of 1200 revolutions per minute for 20 min to obtain a second premix.

[0096] S3. Grind the first premix according to the standard process of three-roll grinding to obtain a first paste.

[0097] S4. Grind the second premix with roll spacings of 8 times and 2 times the particle size of the silver-coated copper powder respectively to obtain a second paste.

[0098] S5. Mix the uniformly ground first paste and second paste evenly, and then perform vacuum centrifugal defoaming to obtain the electronic paste.

[0099] Example 2

[0100] Example 2 is basically the same as Example 1, and the same parts will not be described again. The differences are as follows: In the method for preparing the electronic paste of this example,

[0101] S1. At room temperature, according to the formula ratio, add thermoplastic polyurethane and isophorone into a stainless-steel container, stir evenly at a speed of 800 revolutions per minute, then add silver powder into the stainless-steel container, and continue to stir at a speed of 800 revolutions per minute for 30 min to obtain a first premix.

[0102] S2. According to the formula ratio, add thermoplastic polyurethane, isophorone and acidic dispersant into a stainless-steel container, stir evenly at a speed of 1000 revolutions per minute, then add silver-coated copper powder into the stainless-steel container, and continue to stir at a speed of 1000 revolutions per minute for 30 min to obtain a second premix.

[0103] The rest is the same as that of Example 1.

[0104] Example 3

[0105] Example 3 is basically the same as Example 1, and the same parts will not be repeated. The differences are as follows: In the preparation method of the electronic paste in this example,

[0106] S1. At room temperature, according to the formulation ratio, add thermoplastic polyurethane and isophorone into a stainless-steel container, stir evenly at a speed of 2000 revolutions per minute, then add silver powder into the stainless-steel container, and continue to stir at a speed of 2000 revolutions per minute for 10 minutes to obtain a first premix;

[0107] S2. According to the formulation ratio, add thermoplastic polyurethane, isophorone and an acidic dispersant into a stainless-steel container, stir evenly at a speed of 2500 revolutions per minute, then add silver-coated copper powder into the stainless-steel container, and continue to stir at a speed of 2500 revolutions per minute for 10 minutes to obtain a second premix.

[0108] The rest is the same as that of Example 1.

[0109] Example 4

[0110] Example 4 is basically the same as Example 1, and the same parts will not be repeated. The differences are as follows: In the preparation method of the electronic paste in this example,

[0111] S4. Grind the second premix by three-roll grinding with the roll spacing of 6 times the particle size of the silver-coated copper powder and 1.8 times the particle size of the silver-coated copper powder respectively to obtain a second paste.

[0112] Example 5

[0113] Example 5 is basically the same as Example 1, and the same parts will not be repeated. The differences are as follows: In the preparation method of the electronic paste in this example,

[0114] S4. Grind the second premix by three-roll grinding with the roll spacing of 10 times the particle size of the silver-coated copper powder and 4 times the particle size of the silver-coated copper powder respectively to obtain a second paste.

[0115] Comparative Example 1

[0116] An electronic paste, comprising raw materials with the following mass percentages: 50 wt% of silver-coated copper powder (silver content 25%), 12 wt% of silver powder, 7 wt% of thermoplastic polyurethane, and 31 wt% of isophorone.

[0117] The preparation method of this electronic paste includes the following steps:

[0118] S1. At room temperature, according to the formula ratio, add thermoplastic polyurethane and isophorone into a stainless-steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver powder into the stainless-steel container, and continue to stir at a speed of 1200 revolutions per minute for 20 min to obtain a first premix;

[0119] S2. According to the formula ratio, add thermoplastic polyurethane and isophorone into a stainless-steel container, stir evenly at a speed of 1200 revolutions per minute, then add silver-coated copper powder into the stainless-steel container, and continue to stir at a speed of 1200 revolutions per minute for 20 min to obtain a second premix.

[0120] S3. Grind the first premix according to the standard process of three-roll grinding to obtain a first slurry;

[0121] S4. Grind the second premix with roll spacings 8 times and 2 times the particle size of the silver-coated copper powder respectively to obtain a second slurry.

[0122] S5. Mix the uniformly ground first slurry and second slurry evenly, and then perform vacuum centrifugal defoaming to obtain the electronic slurry.

[0123] The difference between Comparative Example 1 and Example 1 is that the acidic dispersant is omitted.

[0124] Comparative Example 2

[0125] An electronic slurry, comprising raw materials in the following mass percentages: 50 wt% of silver-coated copper powder (silver content 25%), 12 wt% of silver powder, 7 wt% of thermoplastic polyurethane, and 31 wt% of isophorone.

[0126] The preparation method of this electronic slurry includes the following steps:

[0127] According to the formula ratio, add thermoplastic polyurethane, isophorone, silver-coated copper powder and silver powder into a container, stir with a high-speed disperser for 30 minutes, then grind with a three-roll grinder 4 times, and then perform vacuum centrifugal defoaming to obtain the electronic slurry.

[0128] The difference between Comparative Example 2 and Example 1 is that the acidic dispersant is omitted and the preparation method is different; in Comparative Example 2, all raw materials are mixed evenly and then ground.

[0129] Comparative Example 3

[0130] An electronic slurry, having the same raw materials as in Example 1. The preparation method of this electronic slurry includes:

[0131] According to the formulation ratio, thermoplastic polyurethane, isophorone, acidic dispersant, silver-coated copper powder and silver powder are added to a container and stirred for 30 minutes with a high-speed disperser, then ground 4 times with a three-roll grinder, and then vacuum centrifugally defoamed to obtain the electronic paste.

[0132] The difference between Comparative Example 3 and Example 1 is that the preparation method of the electronic paste is different. In Comparative Example 3, all raw materials are mixed evenly and then ground.

[0133] Comparative Example 4

[0134] An electronic paste has the same raw materials as those in Example 1. In the preparation method of this electronic paste:

[0135] S4. The second premix is ground with a three-roll grinder at roll spacings of 1.2 times and 1.3 times the particle size of the silver-coated copper powder respectively to obtain the second paste.

[0136] The difference between Comparative Example 4 and Example 1 is that the grinding process for the preparation of the electronic paste is different.

[0137] Performance Test

[0138] In the present invention, the electronic devices containing the electronic paste of Examples 1 to 5 and the electronic devices containing the electronic paste of Comparative Examples 1 to 4 are subjected to performance tests.

[0139] The test methods include: using a resistivity tester to test the resistivity, fineness of the electronic paste provided by each example and comparative example, and the resistivity after aging for 240 hours under the conditions of 85 °C / 85% RH. The performance test results are shown in Table 1 below.

[0140] Table 1

[0141]

[0142]

[0143] As can be seen from Table 1, the electronic paste prepared by using the preparation method of the electronic paste provided in Embodiments 1-5 of the present invention has high conductivity and good stability. After the aging performance test, it can still maintain high conductivity and can ensure fineness. For the electronic paste prepared by the preparation method of Comparative Example 1 or 2, no dispersant is added, or the preparation method is slightly different. Its fineness increases, the resistivity increases significantly after aging, and the conductivity decreases. This shows that adding a dispersant to the electronic paste can play a positive and effective role in the grinding process. It can not only improve the grinding efficiency, ensure fineness, but also ensure the conductivity of the conductive components in the electronic paste. Similarly, for the electronic paste prepared by the preparation method of Comparative Example 3 or 4, the conventional grinding process is used, which destroys the structure of the silver-coated copper powder and fails to ensure the conductivity of the silver-coated copper powder and silver powder, thus greatly reducing the conductivity.

[0144] The parts not detailed in the present invention are well-known technologies to those skilled in the art.

[0145] In the specific embodiments and the claims, a list of items connected by the terms "at least one of", "at least one of", "at least one kind of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an electronic paste, characterized in that, it comprises the following steps: Mix silver powder, a first resin and a first solvent evenly to obtain a first premix; Mix silver-coated copper powder, an acidic dispersant, a second resin and a second solvent evenly to obtain a second premix; Grind the first premix and the second premix respectively to obtain a first paste and a second paste, wherein the step of respectively grinding the first premix and the second premix specifically comprises: Place the first premix in a three-roll grinder for grinding to form a paste-like state; Place the second premix in a three-roll grinder for grinding to form a paste-like state, specifically comprising: the distance between the first roll and the second roll in the three-roll grinder is 6-10 times the particle size of the silver-coated copper powder, and the distance between the second roll and the third roll is 1.5-4 times the particle size of the silver-coated copper powder; Mix the first paste and the second paste evenly to obtain the electronic paste.

2. The method for preparing an electronic paste according to claim 1, characterized in that, the step of mixing the silver powder, the first resin and the first solvent evenly specifically comprises: Add the first resin and the first solvent into a container, stir evenly at a first rotation speed, and then add the silver powder into the container and stir evenly at a second rotation speed; the first rotation speed and the second rotation speed are respectively 500-3000 revolutions per minute; the stirring time at the second rotation speed is 10-30 min.

3. The method for preparing an electronic paste according to claim 1, characterized in that, the step of mixing the silver-coated copper powder, the acidic dispersant, the second resin and the second solvent evenly specifically comprises: Add the second resin, the first solvent and the acidic dispersant into a container, stir evenly at a third rotation speed, and then add the silver-coated copper powder into the container and stir evenly at a fourth rotation speed; the third rotation speed and the fourth rotation speed are respectively 500-3000 revolutions per minute; the stirring time at the fourth rotation speed is 10-30 min.

4. The method for preparing an electronic paste according to claim 1, characterized in that, the step of placing the first premix in a three-roll grinder for grinding comprises: performing three-roll grinding according to the standard process of three-roll grinding; Place the first premix in a three-roll grinder for grinding until the fineness of the material is less than or equal to 10 μm to form a paste-like state.

5. The method for preparing an electronic paste according to any one of claims 1 to 4, characterized in that, an auxiliary agent is added during the preparation of the first premix; or, an auxiliary agent is added during the preparation of the second premix; or, a part of the auxiliary agent is added during the preparation of the first premix, and the remaining part of the auxiliary agent is added during the preparation of the second premix; after mixing the first paste and the second paste evenly, a step of vacuum centrifugal defoaming is further included.

6. The method for preparing an electronic paste according to any one of claims 1 to 4, characterized in that, the mass ratio of the first resin to the second resin is (20-98):(2-80); The mass ratio of the first solvent to the second solvent is (20 to 98):(2 to 80).

7. An electronic paste, characterized in that, the electronic paste is prepared by using the preparation method of the electronic paste according to any one of claims 1 to 6; the electronic paste comprises silver powder, silver-coated copper powder, resin, solvent and acidic dispersant, wherein the resin consists of a first resin and a second resin, and the solvent consists of a first solvent and a second solvent; the acid value of the acidic dispersant is 100 to 200 mg KOH / g; the electronic paste further comprises an auxiliary agent, and the auxiliary agent comprises at least one of a leveling agent, a thickening agent or a rheological auxiliary agent.

8. Use of the preparation method of the electronic paste according to any one of claims 1 to 6 in the preparation of electronic devices.

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