Bonding agent and method of making same, method of making electronic substrates

Abstract

The application discloses a bonding agent and a preparation method thereof, and a preparation method of an electronic substrate. The preparation method of the bonding agent comprises the following steps: mixing a zeolite imidazolate framework material with modified polydimethylsiloxane, adding a catalyst, and performing reaction under an inert atmosphere to obtain the zeolite imidazolate framework material with the surface grafted modified polydimethylsiloxane. The bonding agent provided by the application can solve the current situation that the bonding force between a traditional copper-clad plate copper foil and an insulating substrate is insufficient, effectively improve the anti-peeling strength of the copper foil, and provide a solid guarantee for the application of high-performance copper-clad plates in the fields of high-frequency and high-speed electronic circuits.

Description

Technical Field

[0001] This application relates to the field of electronic materials technology, and in particular to a bonding agent and its preparation method and a method for preparing electronic substrates. Background Technology

[0002] With the rapid development of 5G electronic information technology, electronic circuit substrates (mainly copper-clad laminates) are moving towards higher frequencies and higher speeds. High-frequency, high-speed signal transmission results in signal loss, with the loss increasing at higher frequencies. This loss primarily stems from dielectric and conductor losses. Especially in the 30 GHz to 300 GHz band, the skin effect makes the roughness of the copper foil interface significantly impact signal transmission.

[0003] Therefore, developing copper surface treatment processes with no or low roughness has become a new challenge in the manufacturing of high-frequency, high-speed electronic circuits under 5G communication technology. However, low roughness leads to a decrease in the adhesion between the copper foil and the insulating substrate, which in turn results in a significant reduction in the peel strength of the copper-clad laminate, making it unable to meet the requirements of practical applications. Therefore, while adopting copper surfaces with no or low roughness, how to enhance the adhesion strength between the copper foil and the insulating substrate has become a difficult problem to be solved. Summary of the Invention

[0004] In view of this, this application provides a bonding agent and a method for preparing the same, as well as a method for preparing an electronic substrate.

[0005] The first aspect of this application provides a method for preparing a bonding agent, comprising:

[0006] The zeolite imidazole ester framework material was mixed with modified polydimethylsiloxane, a catalyst was added, and the reaction was carried out under an inert atmosphere to obtain a zeolite imidazole ester framework material with surface grafted modified polydimethylsiloxane.

[0007] In some embodiments, the catalyst includes at least one of dibutyltin titanate dilaurate, stannous octoate, or triethylamine.

[0008] In some embodiments, the modified polydimethylsiloxane is a polydimethylsiloxane with functional groups modified at the end of its chain segments, the functional groups including at least one selected from mercapto, amino, aminopropyl, vinyl, hydroxy, hydroxymethyl, or glycidyl ether.

[0009] In some embodiments, the modified polydimethylsiloxane includes at least one of mercaptopropyl-terminated polydimethylsiloxane, bis(3-aminopropyl)-terminated polydimethylsiloxane, vinyl-terminated dimethylpolysiloxane, hydroxyl silicone oil, diglycidyl ether-terminated polydimethylsiloxane, hydroxyalkyl-dextrin-terminated polydimethylsiloxane, polydimethylsiloxane alcohol hydroxystearate, monoglycidyl ether-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, hydroxymethyl-terminated polydimethylsiloxane, or (mercapto)methylsiloxane-dimethylsiloxane copolymer.

[0010] In some embodiments, the modified polydimethylsiloxane is a polydimethylsiloxane with thiol groups modified at the chain ends.

[0011] In some embodiments, the amount of modified polydimethylsiloxane is 15wt% to 30wt% of the zeolite imidazole ester framework material, and the amount of catalyst is 2wt% to 6wt% of the modified polydimethylsiloxane.

[0012] In some embodiments, the reaction temperature is 60°C to 100°C, and the reaction time is 5 hours to 8 hours.

[0013] In some embodiments, the preparation method of the zeolite imidazole ester framework material includes: reacting an imidazole organic compound with a zinc salt at 60℃~130℃ for 2h~6h, wherein the molar ratio of the imidazole organic compound to the zinc salt is (2~3):1.

[0014] A second aspect of this application provides a bonding agent prepared according to the above-described preparation method.

[0015] A third aspect of this application provides a method for preparing an electronic substrate, comprising: coating the aforementioned bonding agent onto the surface of a copper foil, and pressing the copper foil coated with the bonding agent onto a substrate.

[0016] This application describes the preparation of an organic-inorganic hybrid bonding agent by grafting polydimethylsiloxane onto the surface of a zeolite imidazole ester framework material. This bonding agent can form coordination bonds with inorganic metals (i.e., copper foil) and also form chemical and physical adsorption interactions with the surface of an organic insulating substrate, establishing a strong bonding system between the copper foil and the insulating substrate. This ensures the adhesion between the copper foil and the insulating substrate while using low-roughness copper foil. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation method of the bonding agent provided in one embodiment of this application. Detailed Implementation

[0018] The embodiments of this application are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The reagents and materials described in the following embodiments are all commercially available.

[0019] Please see Figure 1 This application provides a method for preparing a bonding agent, comprising: mixing a zeolite imidazole ester framework material with modified polydimethylsiloxane (i.e., modified PDMS), adding a catalyst, and reacting under an inert atmosphere to obtain a zeolite imidazole ester framework material with surface grafted modified polydimethylsiloxane.

[0020] The bonding agent provided in this application can, on the one hand, coordinate and bond with copper atoms on the surface of copper foil in copper-clad laminate through zeolite imidazole ester framework material (i.e., ZIF-8 nanoparticles). On the other hand, the grafted modified polydimethylsiloxane segments have flexibility and heat resistance, and can form chemical and physical adsorption effects with the surface of the insulating substrate of copper-clad laminate. This allows the bonding agent to build a strong connection system between copper foil and insulating substrate, ensuring the bonding force between copper foil and insulating substrate while using low-roughness copper foil.

[0021] In some embodiments, the preparation method of zeolite imidazole ester framework material includes: reacting imidazole organic compounds with zinc salts at 60℃~130℃ for 2h~6h, wherein the molar ratio of imidazole organic compounds to zinc salts is (2~3):1.

[0022] For example, imidazole organic compounds and zinc salts can react at temperatures of 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, or any value within the range of any two of the above values; the reaction time between imidazole organic compounds and zinc salts can be 2h, 3h, 4h, 5h, 6h, or any value within the range of any two of the above values; the molar ratio of imidazole organic compounds to zinc salts can be 2:1, 2.5:1, 3:1, or any value within the range of any two of the above values. Controlling the synthesis conditions of zeolite imidazole ester framework materials within the above ranges is beneficial for the successful preparation of zeolite imidazole ester framework materials.

[0023] In some embodiments, the imidazole organic compound may be at least one of dimethylimidazole or benzimidazole, and the zinc salt may be one or more of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, or zinc citrate.

[0024] In some embodiments, the modified polydimethylsiloxane is a polydimethylsiloxane with functional groups modified at the end of its segments, including at least one of mercapto, amino, aminopropyl, vinyl, hydroxy, hydroxymethyl, or glycidyl ether. These functional groups help increase the chemical and physical adsorption between the siloxane segments and the insulating substrate, thereby enhancing the bonding strength between the bonding agent and the surface of the insulating substrate.

[0025] In some embodiments, the modified polydimethylsiloxane includes at least one of mercaptopropyl-terminated polydimethylsiloxane, bis(3-aminopropyl)-terminated polydimethylsiloxane, vinyl-terminated dimethylpolysiloxane, hydroxyl silicone oil, diglycidyl ether-terminated polydimethylsiloxane, hydroxyalkyl-dextrin-terminated polydimethylsiloxane, polydimethylsiloxane alcohol hydroxystearate, monoglycidyl ether-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, hydroxymethyl-terminated polydimethylsiloxane, or (mercapto)methylsiloxane-dimethylsiloxane copolymer.

[0026] In some embodiments, the modified polydimethylsiloxane is a polydimethylsiloxane with thiol groups modified at the chain ends. Preferably, the modified polydimethylsiloxane is a polydimethylsiloxane with thiol groups modified at the chain ends. Compared with other functional groups, thiol groups have strong chemical reactivity and can chemically react with active groups such as unsaturated bonds in the insulating substrate of the copper-clad laminate, forming strong interactions such as covalent bonds, thereby exhibiting superior effects in enhancing the peel strength of the copper foil in the copper-clad laminate.

[0027] In some embodiments, the catalyst includes at least one of dibutyltin titanate dilaurate, stannous octoate, or triethylamine.

[0028] In some embodiments, the amount of modified polydimethylsiloxane is 15 wt% to 30 wt% of the zeolite imidazole ester framework material, and the amount of catalyst is 2 wt% to 6 wt% of the modified polydimethylsiloxane. For example, the amount of modified polydimethylsiloxane can be 15 wt%, 18 wt%, 20 wt%, 23 wt%, 25 wt%, 28 wt%, 30 wt% of the zeolite imidazole ester framework material, or any value within the range of any two of the above values; the amount of catalyst can be 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt% of the modified polydimethylsiloxane, or any value within the range of any two of the above values.

[0029] In some embodiments, the reaction temperature between the zeolite imidazole ester framework material and the modified polydimethylsiloxane is 60°C to 100°C, and the reaction time is 5 hours to 8 hours. For example, the reaction temperature can be 60°C, 70°C, 80°C, 90°C, 100°C, or any value within the range of any two of the above values; the reaction time can be 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, or any value within the range of any two of the above values. Controlling the reaction temperature and reaction time between the zeolite imidazole ester framework material and the modified polydimethylsiloxane within the above range is beneficial for the successful grafting of the modified polydimethylsiloxane onto the surface of the zeolite imidazole ester framework material.

[0030] This application also provides bonding agents prepared according to the above preparation method.

[0031] A method for preparing an electronic substrate includes: coating a bonding agent onto the surface of a copper foil, and pressing the copper foil coated with the bonding agent onto a substrate.

[0032] In some embodiments, the bonding agent is dispersed in a solvent before coating, and the dispersion concentration of the bonding agent is 10 wt% to 15 wt%. For example, the dispersion concentration can be 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, or any value within the range of any two of the above values.

[0033] In some embodiments, the copper foil coated with bonding agent is laminated to the substrate.

[0034] The technical solution of this application will be further explained below with reference to specific implementation methods.

[0035] Example 1

[0036] Dimethylimidazole and zinc nitrate were dissolved in methanol at a molar ratio of 2:1, and the mixture was then stirred at 120°C for 3 hours. After the reaction was complete, centrifugation and washing were performed to obtain pure ZIF-8 nanoparticles.

[0037] ZIF-8 nanoparticles were uniformly dispersed in a toluene solution, which was pre-added with mercaptopropyl-terminated polydimethylsiloxane and dibutyltin dilaurate. The amount of mercaptopropyl-terminated polydimethylsiloxane was 20 wt% of the ZIF-8 nanoparticles, and the amount of dibutyltin dilaurate was 3 wt% of the mercaptopropyl-terminated polydimethylsiloxane. The reaction was carried out at 80 °C for 6 h under argon protection to obtain the bonding agent.

[0038] The steps for applying bonding agents in copper clad laminates are as follows:

[0039] S1. Pre-treatment of copper foil: The copper foil is ultrasonically cleaned in acetone and ethanol in sequence to thoroughly remove oil and impurities from the surface of the copper foil. After cleaning, it is dried for later use.

[0040] S2. Coating the bonding agent: The prepared bonding agent is uniformly dispersed in a volatile isopropanol solvent with a dispersion concentration of 10wt%. The bonding agent solution is coated onto the pretreated copper foil surface by spraying. After coating, it is dried at 80℃ for 30 minutes to allow the isopropanol solvent to completely evaporate, and the bonding agent forms a uniform and stable coating on the copper foil surface.

[0041] S3. Lamination with insulating substrate: The copper foil coated with bonding agent is laminated with the insulating substrate. The lamination is carried out for 150 minutes under the conditions of vacuum degree of 3Kpa, pressure of 8MPa and temperature of 360℃, so that the insulating substrate and the copper foil are tightly bonded to form a copper-clad laminate.

[0042] Example 2

[0043] Dimethylimidazole and zinc nitrate were dissolved in methanol at a molar ratio of 3:1, and the mixture was then stirred at 120°C for 4 hours. After the reaction was complete, centrifugation and washing were performed to obtain pure ZIF-8 nanoparticles.

[0044] ZIF-8 nanoparticles were uniformly dispersed in a toluene solution, which was pre-added with mercaptopropyl-terminated polydimethylsiloxane and dibutyltin dilaurate. The amount of mercaptopropyl-terminated polydimethylsiloxane was 30 wt% of the ZIF-8 nanoparticles, and the amount of dibutyltin dilaurate was 6 wt% of the mercaptopropyl-terminated polydimethylsiloxane. The reaction was carried out at 80 °C for 8 h under argon protection to obtain the bonding agent.

[0045] The steps for applying bonding agents in copper clad laminates are as follows:

[0046] S1. Pre-treatment of copper foil: The copper foil is ultrasonically cleaned in acetone and ethanol in sequence to thoroughly remove oil and impurities from the surface of the copper foil. After cleaning, it is dried for later use.

[0047] S2. Coating the bonding agent: The prepared bonding agent is uniformly dispersed in a volatile isopropanol solvent with a dispersion concentration of 15wt%. The bonding agent solution is coated onto the pretreated copper foil surface by spraying. After coating, it is dried at 100℃ for 20 minutes to allow the isopropanol solvent to completely evaporate, and the bonding agent forms a uniform and stable coating on the copper foil surface.

[0048] S3. Lamination with insulating substrate: The copper foil coated with bonding agent is laminated with the insulating substrate. The lamination is carried out for 120 minutes under the conditions of vacuum degree of 3Kpa, pressure of 7MPa and temperature of 380℃, so that the insulating substrate and the copper foil are tightly bonded to form a copper-clad laminate.

[0049] Example 3

[0050] Dimethylimidazole and zinc nitrate were dissolved in methanol at a molar ratio of 2:1, and the mixture was then stirred at 120°C for 3 hours. After the reaction was complete, centrifugation and washing were performed to obtain pure ZIF-8 nanoparticles.

[0051] ZIF-8 nanoparticles were uniformly dispersed in a toluene solution, which was pre-added with bis(3-aminopropyl)-terminated polydimethylsiloxane and dibutyltin dilaurate. The amount of bis(3-aminopropyl)-terminated polydimethylsiloxane was 20 wt% of the ZIF-8 nanoparticles, and the amount of dibutyltin dilaurate was 3 wt% of the bis(3-aminopropyl)-terminated polydimethylsiloxane. The reaction was carried out at 80 °C for 6 h under argon protection to obtain the bonding agent.

[0052] The steps for applying bonding agents in copper clad laminates are as follows:

[0053] S1. Pre-treatment of copper foil: The copper foil is ultrasonically cleaned in acetone and ethanol in sequence to thoroughly remove oil and impurities from the surface of the copper foil. After cleaning, it is dried for later use.

[0054] S2. Coating the bonding agent: The prepared bonding agent is uniformly dispersed in a volatile isopropanol solvent with a dispersion concentration of 10wt%. The bonding agent solution is coated onto the pretreated copper foil surface by spraying. After coating, it is dried at 80℃ for 30 minutes to allow the isopropanol solvent to completely evaporate, and the bonding agent forms a uniform and stable coating on the copper foil surface.

[0055] S3. Lamination with insulating substrate: The copper foil coated with bonding agent is laminated with the insulating substrate. The lamination is carried out for 150 minutes under the conditions of vacuum degree of 3Kpa, pressure of 8MPa and temperature of 360℃, so that the insulating substrate and the copper foil are tightly bonded to form a copper-clad laminate.

[0056] Example 4

[0057] Dimethylimidazole and zinc nitrate were dissolved in methanol at a molar ratio of 3:1, and the mixture was then stirred at 120°C for 4 hours. After the reaction was complete, centrifugation and washing were performed to obtain pure ZIF-8 nanoparticles.

[0058] ZIF-8 nanoparticles were uniformly dispersed in a toluene solution, which was pre-added with hydroxyalkyl-terminated polydimethylsiloxane and dibutyltin dilaurate. The amount of hydroxyalkyl-terminated polydimethylsiloxane was 30 wt% of the ZIF-8 nanoparticles, and the amount of dibutyltin dilaurate was 6 wt% of the hydroxyalkyl-terminated polydimethylsiloxane. The reaction was carried out at 80 °C for 8 h under argon protection to obtain the bonding agent.

[0059] The steps for applying bonding agents in copper clad laminates are as follows:

[0060] S1. Pre-treatment of copper foil: The copper foil is ultrasonically cleaned in acetone and ethanol in sequence to thoroughly remove oil and impurities from the surface of the copper foil. After cleaning, it is dried for later use.

[0061] S2. Coating the bonding agent: The prepared bonding agent is uniformly dispersed in a volatile isopropanol solvent with a dispersion concentration of 15wt%. The bonding agent solution is coated onto the pretreated copper foil surface by spraying. After coating, it is dried at 100℃ for 20 minutes to allow the isopropanol solvent to completely evaporate, and the bonding agent forms a uniform and stable coating on the copper foil surface.

[0062] S3. Lamination with insulating substrate: The copper foil coated with bonding agent is laminated with the insulating substrate. The lamination is carried out for 120 minutes under the conditions of vacuum degree of 3Kpa, pressure of 7MPa and temperature of 380℃, so that the insulating substrate and the copper foil are tightly bonded, and finally a copper-clad laminate is formed.

[0063] Examples 1-4 use the same copper foil and insulating substrate to make copper-clad laminates.

[0064] Comparative Example 1

[0065] The only difference between Comparative Example 1 and Example 1 is that the mercaptopropyl-terminated polydimethylsiloxane in Comparative Example 1 is replaced with polydimethylsiloxane, as detailed in Tables 1 and 2.

[0066] Performance Testing

[0067] The test method for peel strength is as follows:

[0068] Sample preparation: A sample with a length of 120 mm and a width of 70 mm was cut from an area more than 2.54 mm from the edge of the laminated copper-clad board. Anti-corrosion tape was applied to the sample, and three test strips with a width of 3.18 mm and a length of 100 mm were made in the sample area using ferric chloride etching solution.

[0069] Sample measurement: Using a universal testing machine, with the copper foil side of the test strip facing upwards, align the test strip with the center of the sample holder, place the pin plate on top of the test strip, insert the clamping head into the hole, align the copper foil strip with the inclined groove, clamp the copper foil strip, and make the peeling direction 90 degrees with the insulating substrate, and start peeling at a rate of 50.8 mm / min.

[0070] Peel strength = minimum peel force / sample width.

[0071] The peel strength of Examples 1 to 4 and Comparative Example 1 were tested according to the above method, and the test results are shown in Table 2.

[0072] Table 1

[0073]

[0074] Table 2

[0075]

[0076] As can be seen from Tables 1 and 2, the bonding agent provided in this application enables the copper foil of the copper-clad laminate to have good bonding force and high peel strength.

[0077] Compared with Comparative Example 1, Example 1 uses modified polydimethylsiloxane. The siloxane segments of the modified polydimethylsiloxane have chemical and physical adsorption effects with the insulating substrate, which can enhance the peel strength between the copper foil and the insulating substrate.

[0078] A comparison of Examples 1 and 3, and Examples 2 and 4, shows that when the modified polydimethylsiloxane chain segments contain thiol functional groups, the thiol functional groups enhance the interaction between the bonding agent and the insulating substrate, resulting in higher peel strength between the copper foil and the insulating substrate.

[0079] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A method for preparing a bonding agent, characterized in that, include: The zeolite imidazole ester framework material was mixed with modified polydimethylsiloxane, a catalyst was added, and the reaction was carried out under an inert atmosphere to obtain a zeolite imidazole ester framework material with surface grafted modified polydimethylsiloxane. The modified polydimethylsiloxane is a polydimethylsiloxane with functional groups modified at the end of its chain segments, wherein the functional groups are at least one of mercapto, amino, aminopropyl, vinyl, hydroxy, hydroxymethyl, or glycidyl ether.

2. The method for preparing the bonding agent as described in claim 1, characterized in that, The catalyst includes at least one of dibutyltin dilaurate, tetrabutyl titanate, stannous octoate, or triethylamine.

3. The method for preparing the bonding agent as described in claim 1, characterized in that, The modified polydimethylsiloxane includes at least one of the following: mercaptopropyl-terminated polydimethylsiloxane, bis(3-aminopropyl)-terminated polydimethylsiloxane, vinyl-terminated dimethylpolysiloxane, hydroxyl silicone oil, diglycidyl ether-terminated polydimethylsiloxane, hydroxyalkyl-dextrin-terminated polydimethylsiloxane, polydimethylsiloxane alcohol hydroxystearate, monoglycidyl ether-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, hydroxymethyl-terminated polydimethylsiloxane, or (mercapto)methylsiloxane-dimethylsiloxane copolymer.

4. The method for preparing the bonding agent as described in claim 1, characterized in that, The modified polydimethylsiloxane is a polydimethylsiloxane with thiol groups modified at the end of its chain segments.

5. The method for preparing the bonding agent as described in claim 1, characterized in that, The amount of the modified polydimethylsiloxane is 15wt% to 30wt% of the zeolite imidazole ester skeleton material, and the amount of the catalyst is 2wt% to 6wt% of the modified polydimethylsiloxane.

6. The method for preparing the bonding agent as described in claim 1, characterized in that, The reaction temperature is 60℃~100℃, and the reaction time is 5h~8h.

7. The method for preparing the bonding agent according to claim 1, characterized in that, The preparation method of the zeolite imidazole ester framework material includes: reacting an imidazole organic compound with a zinc salt at 60℃~130℃ for 2h~6h, wherein the molar ratio of the imidazole organic compound to the zinc salt is (2~3):

1.

8. A bonding agent, characterized in that, The bonding agent is prepared by the method according to any one of claims 1-7.

9. A method for preparing an electronic substrate, characterized in that, include: The bonding agent of claim 8 is coated onto the surface of a copper foil, and the copper foil coated with the bonding agent is pressed onto a substrate.

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