Conductive paste, preparation method thereof and metamaterial microstructure

Abstract

The present invention provides a conductive paste, a preparation method thereof and a metamaterial microstructure. In parts by weight, the raw materials of the conductive paste include 75 to 83 parts of nano metal powder, 0.5 to 1 part of polytetrafluoroethylene wax, 0.5 to 1 part of a curing agent, 1 to 1.5 parts of a viscosity regulator, 17 to 25 parts of a high temperature resistant resin and 11 to 25 parts of an organic solvent. The above raw materials not only use a high temperature resistant resin, but also add a viscosity regulator, and also add polytetrafluoroethylene wax for lubrication. By adjusting the ratio of the above components to the above range, experiments have shown that the conductive paste can not only have a lower viscosity and a higher temperature resistance, but also have a higher filler filling rate, thereby ensuring that the conductive paste has a very high conductivity. In addition, the above conductive paste can also have excellent silk screen stability.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive materials, and in particular to a conductive paste, a preparation method thereof and a metamaterial microstructure. Background Art

[0002] At present, most of the screen printing silver pastes are resistant to temperatures below 120°C, and a few conductive silver pastes can reach high temperature resistance of 180°C. However, the above-mentioned high temperature resistant conductive silver paste has the problem of high viscosity, which makes it difficult for the silver paste to leak to the substrate when screen printing 400 mesh gauze, and the screen printed microstructure has the problem of breakpoints and short lines, so it can only be used in gauze with a mesh count of more than 200 meshes, which makes it impossible to produce metamaterial microstructures with line width and line spacing requirements of 70-100μm. Summary of the invention

[0003] The main purpose of the present invention is to provide a conductive paste, a preparation method thereof and a metamaterial microstructure to solve the problem in the prior art that the conductive paste cannot have both high temperature resistance and low viscosity.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a conductive paste is provided. The raw materials of the conductive paste include 75 to 83 parts of nano metal powder, 0.5 to 1 part of polytetrafluoroethylene wax, 0.5 to 1 part of curing agent, 1 to 1.5 parts of viscosity regulator, 17 to 25 parts of high temperature resistant resin and 11 to 25 parts of organic solvent, by weight.

[0005] Furthermore, the molecular weight of the high temperature resistant resin is less than 600.

[0006] Furthermore, the high temperature resistant resin is a modified epoxy resin and / or a bismaleimide resin.

[0007] Furthermore, the viscosity modifier is selected from any one or more of polyphenylene ether, polysulfone resin and epoxy resin, and the molecular weight of the epoxy resin is 200-450.

[0008] Furthermore, the conductive paste further comprises a coupling agent, preferably the weight portion of the coupling agent is 1 to 2, and preferably the coupling agent is a silane coupling agent.

[0009] Furthermore, the conductive paste further comprises a curing accelerator, and preferably the weight proportion of the curing accelerator is 0.5 to 0.7.

[0010] Furthermore, the conductive paste further comprises a dispersing aid, and preferably the weight portion of the dispersing aid is 0.5 to 1.

[0011] According to another aspect of the present invention, a method for preparing the above-mentioned conductive paste is provided, comprising the following steps: mixing raw materials including nano metal powder, polytetrafluoroethylene wax, a curing agent, a viscosity regulator, a high temperature resistant resin and an organic solvent to obtain a conductive paste.

[0012] Furthermore, the preparation method includes the following steps: stirring the first raw material including nano metal powder, polytetrafluoroethylene wax, curing agent, viscosity regulator and organic solvent for the first time to obtain a first mixture, preferably the first stirring time is 10 to 15 minutes and the temperature is 20 to 35°C; stirring the first mixture with a high temperature resistant resin for a second time to obtain a conductive paste, preferably the second stirring time is 10 to 15 minutes and the temperature is 40 to 50°C.

[0013] According to another aspect of the present invention, there is also provided a metamaterial microstructure, which is formed by curing raw materials including a conductive paste, and the conductive paste is the conductive paste mentioned above.

[0014] The technical solution of the present invention is applied to provide a conductive paste, wherein the raw materials of the conductive paste include 75-83 parts of nano metal powder, 0.5-1 parts of polytetrafluoroethylene wax, 0.5-1 parts of curing agent, 1-1.5 parts of viscosity regulator, 17-25 parts of high temperature resistant resin and 13-21 parts of organic solvent by weight. The above raw materials not only use high temperature resistant resin, but also add viscosity regulator, and also add polytetrafluoroethylene wax for lubrication, so that by adjusting the ratio of the above components to the above range, experiments show that the conductive paste can not only have lower viscosity and higher temperature resistance, but also have higher filler filling rate, so as to ensure that the conductive paste has very high conductivity. In addition, the above conductive paste can also have excellent screen printing stability. DETAILED DESCRIPTION

[0015] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0016] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0017] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0018] As introduced in the background technology, the conductive silver paste in the prior art with high temperature resistance of up to 180°C has a high viscosity problem, which makes it difficult for the silver paste to leak onto the substrate when screen printing a 400-mesh mesh. The screen-printed microstructure has breakpoints and short lines, making it impossible to produce a metamaterial microstructure with a line width and line spacing requirement of 70 to 100 μm.

[0019] The inventors of the present invention have conducted research on the above-mentioned problems and proposed a conductive paste. The raw materials of the conductive paste include 75 to 83 parts of nano metal powder, 0.5 to 1 part of polytetrafluoroethylene wax, 0.5 to 1 part of a curing agent, 1 to 1.5 parts of a viscosity regulator, 17 to 25 parts of a high temperature resistant resin and 11 to 25 parts of an organic solvent, measured by weight.

[0020] The nano metal powder may be nano silver powder, and in this case the conductive paste may be conductive silver paste.

[0021] The above raw materials not only use high temperature resistant resin, but also add viscosity regulator, and also add polytetrafluoroethylene wax which plays a lubricating role. By adjusting the ratio of the above components to the above range, experiments have proved that the conductive paste can not only have lower viscosity and higher temperature resistance, but also have a higher filler filling rate, thereby ensuring that the conductive paste has very high conductivity. In addition, the above conductive paste can also have excellent silk screen stability.

[0022] In order to reduce the viscosity of the conductive paste while ensuring its high temperature resistance, preferably, the molecular weight of the high temperature resistant resin in the conductive paste is less than 600. More preferably, the high temperature resistant resin is a modified epoxy resin and / or bismaleimide resin (BMI). The modified epoxy resin made by Huibo New Materials is preferred.

[0023] The raw materials of the conductive paste of the present invention include a viscosity modifier, which is used to reduce the viscosity of the conductive paste. The viscosity modifier can be selected from any one or more of polyphenylene ether, polysulfone resin and epoxy resin, and the molecular weight of the epoxy resin is 200 to 450. However, it is not limited to the above preferred types, and those skilled in the art can reasonably select the type of the viscosity modifier according to the prior art.

[0024] The raw materials of the conductive paste of the present invention include a curing agent, and the curing agent may be butyl carbitol and / or butyl carbitol acetate.

[0025] The raw materials of the conductive paste of the present invention may further include a coupling agent. In order to reduce the viscosity of the conductive paste while ensuring its high temperature resistance, preferably, the weight portion of the coupling agent is 1 to 2, and the coupling agent may be a silane coupling agent.

[0026] The raw materials of the conductive paste of the present invention may also include a curing accelerator. In order to improve the curing efficiency of the conductive paste, preferably, the weight portion of the curing accelerator is 0.5 to 0.7. Those skilled in the art can reasonably select the type of the curing accelerator based on the prior art. For example, the curing accelerator may be any one or more of benzyldimethylamine, 2,3,6-tris(dimethylaminomethyl)phenol and methyltetrahydrophthalic anhydride.

[0027] The raw materials of the conductive paste of the present invention may also include a dispersing aid. In order to improve the dispersing effect of the nano metal powder and the polytetrafluoroethylene wax in the high temperature resistant resin, preferably, the weight portion of the dispersing aid is 0.5 to 1. Those skilled in the art may also reasonably select the type of the dispersing aid based on the prior art, such as the dispersing aid may include any one or more of polyvinyl pyrrolidone, polyvinyl alcohol, hydroxymethyl cellulose and polyetheretherketone.

[0028] According to another aspect of the present invention, a method for preparing the above-mentioned conductive paste is also provided, comprising the following steps: mixing raw materials including nano metal powder, polytetrafluoroethylene wax, a curing agent, a viscosity regulator, a high temperature resistant resin and an organic solvent to obtain the above-mentioned conductive paste.

[0029] In a preferred embodiment, the preparation method comprises the following steps: stirring a first raw material comprising nano metal powder, polytetrafluoroethylene wax, a curing agent, a viscosity regulator and an organic solvent for a first time to obtain a first mixture; stirring the first mixture with a high temperature resistant resin for a second time to obtain a conductive paste.

[0030] In the above preferred embodiment, in order to improve the dispersion effect of nano metal powder and polytetrafluoroethylene wax in the high temperature resistant resin, it is more preferred that the first stirring time is 10 to 15 minutes and the temperature is 20 to 35°C; and, more preferably, the second stirring time is 10 to 15 minutes and the temperature is 40 to 50°C.

[0031] According to another aspect of the present invention, there is also provided a metamaterial microstructure, which is formed by curing raw materials including the above-mentioned conductive paste.

[0032] Since the raw materials for forming the above-mentioned metamaterial microstructure include the above-mentioned conductive paste, and the raw materials of the conductive paste not only use high-temperature resistant resins, but also add viscosity regulators, and also add polytetrafluoroethylene wax that acts as a lubricant, by adjusting the ratio of the above-mentioned components to the above-mentioned range, the conductive paste can not only have lower viscosity and higher temperature resistance, but also have a higher filler filling rate, thereby not only improving the temperature resistance of the metamaterial microstructure, but also effectively avoiding the occurrence of breakpoints and short lines when the above-mentioned conductive paste is used for screen printing to form the metamaterial microstructure, and has excellent screen printing stability.

[0033] The above-mentioned conductive paste and the preparation method thereof of the present invention will be further described below in combination with examples and comparative examples.

[0034] Examples 1 to 5, Comparative Examples 1 to 3

[0035] The above embodiment and comparative example respectively provide a method for preparing a conductive paste, comprising the following steps:

[0036] Nano metal powder (particle size of 100-500 nm), polytetrafluoroethylene wax (particle size of 1-3 μm), curing agent, viscosity regulator (polyphenylene ether, manufacturer: SABIC) and organic solvent (dimethyl succinate, DuPont DBE) were stirred in a stirring kettle for 30 minutes according to the ratio (parts by weight) in Table 1 to prepare a mixed solution, and then a high temperature resistant resin was added and stirred for another 30 minutes, wherein the curing agent was butyl carbitol and the high temperature resistant resin was a modified epoxy resin (manufacturer: Huibo New Materials).

[0037] Example 6

[0038] The difference between this comparative example and Example 5 is:

[0039] The high temperature resistant resin also includes bismaleimide resin (Baichen New Materials), and the usage ratio of the high temperature resistant resin and the bismaleimide resin is 1:1.

[0040] The raw materials of the mixed solutions prepared in the above-mentioned Examples 4 to 6 also include a curing accelerator and a dispersing aid. The curing accelerator is benzyl dimethylamine, and the dispersing aid is water-based polyether ether ketone.

[0041] Comparative Example 4

[0042] The difference between this comparative example and Example 5 is:

[0043] Use non-high temperature resistant resin (model YD-171, Guodu) with the same proportion.

[0044] Table 1

[0045]

[0046]

[0047] The silver paste in the above-mentioned embodiments and comparative examples was scraped on a glass slide with high-temperature resistant tapes on both sides. The high-temperature resistant tape was cut to leave a gap in the middle, and the silver paste was scraped through the gap. The conductivity data after the length and thickness of the gap were tested. The test method was based on GJB548A-1996; conductivity σ=1 / ρ, and the silver paste formed a conductive adhesive after curing. The test results in Example 1 are shown in Table 2, the test results in Example 2 are shown in Table 3, and the test results in Example 3 are shown in Table 4. The glass slides, sample widths and lengths, and curing conditions used in Examples 4 to 6 and Comparative Example 4 are the same as those in Example 3. The test results of average resistivity and conductivity are shown in Tables 5 to 8, respectively.

[0048] Table 2

[0049]

[0050]

[0051] Table 3

[0052]

[0053] Table 4

[0054]

[0055] Table 5

[0056]

[0057]

[0058] Table 6

[0059]

[0060] Table 7

[0061]

[0062] Table 8

[0063]

[0064]

[0065] It can be seen that the conductivity of the samples in Examples 1 to 6 did not change significantly under the conditions of 200° C. and 4 hours, while the conductivity of the sample in Comparative Example 4 changed significantly.

[0066] Moreover, after the conductive pastes in Examples 1 to 6 were printed on a 400-mesh steel screen, the measured circuit line width and line spacing could reach 70 to 100 microns without any breakpoint or short line phenomenon. However, the conductive pastes in Comparative Examples 1 to 3 all had breakpoint and short line phenomena to varying degrees after screen printing.

[0067] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0068] 1) The conductive paste can not only have lower viscosity and higher temperature resistance, but also have a higher filler filling rate, thereby ensuring that the conductive paste has very high conductivity;

[0069] 2) The conductive paste can also have excellent screen printing stability.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a conductive paste, characterized in that: The following steps are involved: In parts by weight, the raw materials of the conductive paste include 75-83 parts of nano metal powder, 0.5-1 parts of polytetrafluoroethylene wax, 0.5-1 parts of curing agent, 1-1.5 parts of viscosity regulator, 17-25 parts of high temperature resistant resin and 11-25 parts of organic solvent; The viscosity modifier is selected from any one or more of polyphenylene ether, polysulfone resin and epoxy resin; Stirring the first raw material including the nano metal powder, the polytetrafluoroethylene wax, the curing agent, the viscosity regulator and the organic solvent for the first time to obtain a first mixed material, wherein the first stirring time is 10-15 minutes and the temperature is 20-35° C.; The first mixed material and the high temperature resistant resin are stirred for a second time to obtain the conductive paste, and the second stirring time is 10-15 minutes and the temperature is 40-50°C.

2. The method for preparing the conductive paste according to claim 1, characterized in that: The molecular weight of the high temperature resistant resin is less than 600.

3. The method for preparing the conductive paste according to claim 2, characterized in that: The high temperature resistant resin is modified epoxy resin and / or bismaleimide resin.

4. The method for preparing the conductive paste according to claim 1, characterized in that: The molecular weight of the epoxy resin is 200-450.

5. The method for preparing a conductive paste according to any one of claims 1 to 4, characterized in that: The conductive paste further includes a coupling agent.

6. The method for preparing the conductive paste according to claim 5, characterized in that: The weight portion of the coupling agent is 1 to 2.

7. The method for preparing the conductive paste according to claim 5, characterized in that: The coupling agent is a silane coupling agent.

8. The method for preparing a conductive paste according to any one of claims 1 to 4, characterized in that: The conductive paste further includes a curing accelerator.

9. The method for preparing the conductive paste according to claim 8, characterized in that: The weight portion of the curing accelerator is 0.5 to 0.

7.

10. The method for preparing a conductive paste according to any one of claims 1 to 4, characterized in that: The conductive paste further includes a dispersing aid.

11. The method for preparing the conductive paste according to claim 10, characterized in that: The weight portion of the dispersing aid is 0.5 to 1.

12. A metamaterial microstructure, formed by curing raw materials including a conductive paste, characterized in that: The conductive paste is prepared by the method for preparing the conductive paste according to any one of claims 1 to 11.

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