A manufacturing method of a flexible high-frequency copper-clad plate

Abstract

The present application relates to a kind of flexible high-frequency copper-clad plate manufacturing method, belong to copper-clad plate preparation technical field.The present application is coated in thermoplastic resin composition on the both sides of modified thermoplastic polyimide film, is baked to be prepared adhesive sheet, again the both sides of prepared adhesive sheet is covered with copper foil, after vacuum pressing condition, obtain flexible high-frequency copper-clad plate.The resin composition is thermoplastic resin composition, and its thermoplastic resin composition includes polytetrafluoroethylene emulsion, perfluoroalkoxy vinyl ether polymer, coupling agent, pH regulator;The modified thermoplastic polyimide film is the thermoplastic polyimide film of surface modification by acid or alkali treatment.The high-frequency flexible copper-clad plate prepared by the present application can be freely bent, wound, folded, has low dielectric property, low hygroscopicity, high peel strength, good processing reliability, suitable for high-frequency flexible application field.

Description

Technical Field

[0001] This invention belongs to the field of copper clad laminate preparation technology, and relates to a method for manufacturing a flexible high-frequency copper clad laminate. Background Technology

[0002] Flexible printed circuit boards (PCBs) are printed circuits made of flexible insulating substrates, possessing many advantages that rigid PCBs lack. They can be freely bent, rolled, and folded, arranged arbitrarily according to spatial layout requirements, and moved and stretched freely in three-dimensional space, thereby achieving integrated component assembly and wire connection. PCBs can significantly reduce the size and weight of electronic products, meeting the needs of electronic products moving towards higher density, miniaturization, and higher reliability.

[0003] As the substrate for flexible circuit boards—flexible copper-clad laminates—regardless of whether they are adhesive-coated or adhesive-free, polyimide (PI) is indispensable. Besides being thin, lightweight, and flexible, flexible copper-clad laminates using polyimide-based films possess excellent bending strength, as well as superior electrical, thermal, and heat resistance properties. Its low dielectric constant (Dk) allows for rapid signal transmission. Good thermal properties facilitate component cooling, and its high glass transition temperature (Tg) enables optimal component operation at higher temperatures.

[0004] However, the PI polyimide film used in traditional flexible copper-clad laminates can no longer meet people's higher demands. The excessive moisture absorption of PI polyimide film reduces the reliability of flexible copper-clad laminates. Problems such as curling caused by moisture absorption of PI polyimide film, oxidation of copper foil and reduction of peel strength caused by moisture evaporation at high temperatures, all cause problems in use.

[0005] With the emergence of new products and the upgrading of existing products, flexible copper-clad laminates are being used more and more frequently in high-frequency fields such as aerospace, military, and mobile communications. In particular, high-frequency flexible copper-clad laminates used as printed circuit boards for outdoor electronic devices not only require low dielectric constant, low dielectric loss, low moisture absorption, and high peel strength, but also good heat dissipation, solderability, and easy assembly. Only by combining rigid and flexible designs can the slight deficiency of high-frequency substrates in component load-bearing capacity be made up to a certain extent.

[0006] Therefore, it is very necessary to develop a high-frequency flexible copper-clad laminate to solve the problems of high moisture absorption, low peel strength, and poor processing reliability of existing PI polyimide film flexible boards after moisture absorption. Summary of the Invention

[0007] The purpose of this invention is to provide a method for manufacturing flexible high-frequency copper-clad laminates, which can be freely bent, rolled, and folded, and has the characteristics of low dielectric properties, low moisture absorption, high peel strength, and good processing reliability.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0010] W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 5-250 μm, and the adhesive layer thickness is controlled at 20-40 μm. The adhesive sheet is prepared by baking at a temperature of 300-350℃ for 15-20 min.

[0011] W2. The prepared bonding sheet is covered with copper foil on both sides and pressed together under vacuum conditions of 380-390℃, 3-4h, and 3-5MPa to obtain a flexible high-frequency copper-clad laminate.

[0012] As a preferred embodiment of the present invention, the thermoplastic resin composition comprises the following components in parts by weight:

[0013] 25-35 parts of polytetrafluoroethylene emulsion;

[0014] 50-65 parts of perfluoroalkoxy vinyl ether polymer;

[0015] 10-15 parts of ternary copolymer polycarbonate;

[0016] 5-10 parts of coupling agent;

[0017] 3-5 parts of pH adjuster.

[0018] As a preferred embodiment of the present invention, the polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene after polymerization in the presence of a nonionic surfactant, with a solid content of 60% and a pH value of 9-10.

[0019] As a preferred embodiment of the present invention, the ternary copolymer polycarbonate is synthesized by isosorbide, diphenyl carbonate, and 1,4-cyclohexanediethanol via a melt transesterification method.

[0020] As a preferred embodiment of the present invention, the coupling agent in the thermoplastic resin composition is an aminosilane coupling agent.

[0021] As a preferred embodiment of the present invention, the pH adjuster in the thermoplastic resin composition is ammonia.

[0022] As a preferred embodiment of the present invention, the modified thermoplastic polyimide film is a thermoplastic polyimide film whose surface has been modified by acid or alkali treatment, and has a thickness of 5 to 250 μm.

[0023] A flexible high-frequency copper-clad laminate prepared according to the above preparation method.

[0024] The beneficial effects of this invention are:

[0025] (1) Adding perfluoroalkoxy vinyl ether polymer and ternary copolymer polycarbonate to polytetrafluoroethylene can greatly improve its heat resistance, while also having good anti-permeability and anti-molecular diffusion properties, and its water absorption rate is also very low, which can greatly improve the reliability of flexible high-frequency copper clad laminate.

[0026] (2) The addition of aminosilane coupling agent and pH adjuster can improve the bonding strength, water resistance and weather resistance of the mixture, and can keep the pH value of the mixture glue stable, so as to avoid the mixed emulsion glue from promoting bacterial growth due to the decrease of pH value, thereby causing abnormal conditions such as odor and scum, which will affect the reliability of flexible high frequency copper clad laminate.

[0027] (3) When the polyimide film comes into contact with acid or alkali, the surface of the polyimide film is etched. Etching can open the imide rings on the surface of the polyimide film, making the material surface reactive. It can form hydrophilic polar groups on the material surface, and at the same time increase its surface roughness, improve the adhesion of the polyimide film surface, and achieve better bonding with thermoplastic compositions, which can greatly improve the reliability of flexible high-frequency copper-clad laminates. Detailed Implementation

[0028] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0029] Example 1

[0030] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0031] W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 50 μm, and the adhesive layer thickness is controlled at 20 μm. The adhesive sheet is prepared by baking at a temperature of 300℃ for 15 min.

[0032] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 380℃, 3h time and 3MPa pressure to obtain a flexible high-frequency copper-clad laminate.

[0033] The thermoplastic resin composition comprises the following components in parts by weight:

[0034] 25 parts of polytetrafluoroethylene emulsion;

[0035] 50 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0036] 10 parts of ternary copolymer polycarbonate (purchased from Mitsubishi Chemical Corporation, Japan);

[0037] 5 parts coupling agent;

[0038] 3 parts pH adjuster.

[0039] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene polymerized in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 9.

[0040] The ternary copolymer polycarbonate is synthesized from isosorbide, diphenyl carbonate, and 1,4-cyclohexanediethanol via a melt transesterification method.

[0041] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0042] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0043] The modified thermoplastic polyimide film is a thermoplastic polyimide film with a surface modified by treatment with 20% hydrochloric acid by mass concentration, and a thickness of 50μm.

[0044] Example 2

[0045] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0046] W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 150 μm, and the adhesive layer thickness is controlled at 30 μm. The adhesive sheet is prepared by baking at a temperature of 325℃ for 17 min.

[0047] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 380~390℃, 3~4h, and 4MPa to obtain a flexible high-frequency copper-clad laminate.

[0048] The thermoplastic resin composition comprises the following components in parts by weight:

[0049] 30 parts of polytetrafluoroethylene emulsion;

[0050] 55 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0051] 12 parts of ternary copolymer polycarbonate (purchased from Mitsubishi Chemical Corporation, Japan);

[0052] 7 parts coupling agent;

[0053] 4 parts pH adjuster.

[0054] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene polymerized in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 9-10.

[0055] The ternary copolymer polycarbonate is synthesized from isosorbide, diphenyl carbonate, and 1,4-cyclohexanediethanol via a melt transesterification method.

[0056] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0057] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0058] The modified thermoplastic polyimide film is a thermoplastic polyimide film with a thickness of 150 μm, whose surface has been modified by treating with a sodium hydroxide solution with a mass concentration of 20%.

[0059] Example 3

[0060] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0061] W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 250 μm, and the adhesive layer thickness is controlled at 40 μm. The adhesive sheet is prepared by baking at a temperature of 350℃ for 20 min.

[0062] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 390℃, 4h and 5MPa to obtain a flexible high-frequency copper-clad laminate.

[0063] The thermoplastic resin composition comprises the following components in parts by weight:

[0064] 35 parts of polytetrafluoroethylene emulsion;

[0065] 65 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0066] 15 parts of ternary copolymer polycarbonate (purchased from Mitsubishi Chemical Corporation, Japan);

[0067] 10 parts coupling agent;

[0068] 5 parts pH adjuster.

[0069] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene after polymerization in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 10.

[0070] The ternary copolymer polycarbonate is synthesized from isosorbide, diphenyl carbonate, and 1,4-cyclohexanediethanol via a melt transesterification method.

[0071] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0072] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0073] The modified thermoplastic polyimide film is a thermoplastic polyimide film with a surface modified by treatment with 20% hydrochloric acid by mass concentration, and a thickness of 250μm.

[0074] Comparative Example 1

[0075] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0076] W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 250 μm, and the adhesive layer thickness is controlled at 40 μm. The adhesive sheet is prepared by baking at a temperature of 350℃ for 20 min.

[0077] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 390℃, 4h and 5MPa to obtain a flexible high-frequency copper-clad laminate.

[0078] The thermoplastic resin composition comprises the following components in parts by weight:

[0079] 35 parts of polytetrafluoroethylene emulsion;

[0080] 65 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0081] 10 parts coupling agent;

[0082] 5 parts pH adjuster.

[0083] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene after polymerization in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 10.

[0084] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0085] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0086] The modified thermoplastic polyimide film is a thermoplastic polyimide film with a surface modified by treatment with 20% hydrochloric acid by mass concentration, and a thickness of 250μm.

[0087] Comparative Example 2

[0088] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0089] W1. A thermoplastic resin composition is coated on both sides of a thermoplastic polyimide film with a thickness of 250 μm, and the adhesive layer thickness is controlled at 40 μm. The adhesive sheet is prepared by baking at a temperature of 350℃ for 20 min.

[0090] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 390℃, 4h and 5MPa to obtain a flexible high-frequency copper-clad laminate.

[0091] The thermoplastic resin composition comprises the following components in parts by weight:

[0092] 35 parts of polytetrafluoroethylene emulsion;

[0093] 65 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0094] 15 parts of ternary copolymer polycarbonate (purchased from Mitsubishi Chemical Corporation, Japan);

[0095] 10 parts coupling agent;

[0096] 5 parts pH adjuster.

[0097] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene after polymerization in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 10.

[0098] The ternary copolymer polycarbonate is synthesized from isosorbide, diphenyl carbonate, and 1,4-cyclohexanediethanol via a melt transesterification method.

[0099] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0100] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0101] Comparative Example 3

[0102] A method for manufacturing a flexible high-frequency copper-clad laminate includes the following steps:

[0103] W1. A thermoplastic resin composition is coated on both sides of a thermoplastic polyimide film with a thickness of 250 μm, and the adhesive layer thickness is controlled at 40 μm. The adhesive sheet is prepared by baking at a temperature of 350℃ for 20 min.

[0104] W2. The prepared bonding sheet is covered with copper foil with a thickness of 35μm on both sides and pressed together under vacuum conditions of 390℃, 4h and 5MPa to obtain a flexible high-frequency copper-clad laminate.

[0105] The thermoplastic resin composition comprises the following components in parts by weight:

[0106] 47 parts of polytetrafluoroethylene emulsion;

[0107] 78 parts of perfluoroalkoxy vinyl ether polymer (purchased from Fucheng Plastics Technology (Shanghai) Co., Ltd.);

[0108] 10 parts coupling agent;

[0109] 5 parts pH adjuster.

[0110] The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of tetrafluoroethylene after polymerization in the presence of alkylphenol polyoxyethylene ether, with a solid content of 60% and a pH value of 10.

[0111] The coupling agent in the thermoplastic resin composition is γ-aminopropyltriethoxysilane.

[0112] The pH adjuster in the thermoplastic resin composition is ammonia water with a mass concentration of 25%.

[0113] Performance testing

[0114] 1. Adhesive film and resin bonding test: Under a metallographic microscope, magnified to 50x or 100x, observe whether there are cracks between the polyimide film and the thermoplastic resin composition in Examples 1-3 and Comparative Examples 1-3. If there are no cracks, it is considered good; if there are cracks, it is considered poor.

[0115] 2. Free bending / winding / folding test: The adhesive sheets in Examples 1 to 3 and Comparative Examples 1 to 3 are bent more than 180° respectively. If there are no cracks, and they can be naturally rolled up and laid flat after folding, and can return to their original shape, they are considered to pass. If they cannot return to their original shape or have cracks, they are considered to fail.

[0116] 3. Dielectric constant: The dielectric constant of the bonding sheets in Examples 1-3 and Comparative Examples 1-3 was determined using the SPDR method at 10 GHz;

[0117] 4. Dielectric loss: The dielectric loss of the bonding sheets in Examples 1-3 and Comparative Examples 1-3 was measured at 10 GHz using the SPDR method.

[0118] 5. Thermal shock test at 288°C for 10 seconds each time: Using copper-clad laminates of 50mm×50mm from Examples 1-3 and Comparative Examples 1-3, immerse them in solder at 288°C for 10 seconds each time. Remove them and check for delamination. Repeat the immersion test 6 times. If there is no delamination, it is considered a pass; if there is delamination, it is considered a fail.

[0119] 6. Copper foil peel strength: The copper-clad laminates in Examples 1-3 and Comparative Examples 1-3 were measured according to the method specified in 2.4.8 of IPC-TM-650.

[0120] 7. Hygroscopicity: The adhesive sheets in Examples 1-3 and Comparative Examples 1-3 were measured according to the method specified in 2.6.2.1 of IPC-TM-650.

[0121] 8. Moisture absorption curling test: After completing the moisture absorption test, place the 100mm×100mm adhesive sheet sample on a flat surface and visually inspect for curling. If there is no curling, it is considered a pass; if there is curling, it is considered a fail.

[0122] The test results are shown in Table 1 below:

[0123] Table 1

[0124]

[0125] As can be seen from the data in Table 1 above, the adhesive sheets prepared by applying Examples 1 to 3 of the present invention have good bonding between the modified PI polyimide film and the thermoplastic resin composition, and the flexible high-frequency copper-clad laminates prepared therefrom can be freely bent, rolled, and folded. They have excellent dielectric properties, good heat resistance, high peel strength, low moisture absorption, and no curling phenomenon after moisture absorption, making them very suitable for application in the field of high-frequency flexible boards.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for manufacturing a flexible high-frequency copper-clad laminate, characterized in that, Includes the following steps: W1. A thermoplastic resin composition is coated on both sides of a modified thermoplastic polyimide film with a thickness of 5-250 μm, the adhesive layer thickness is controlled at 20-40 μm, and an adhesive sheet is prepared by baking at a temperature of 300-350℃ for 15-20 min; wherein the modified thermoplastic polyimide film is a thermoplastic polyimide film whose surface has been modified by acid or alkali treatment; W2. The prepared bonding sheet is covered with copper foil on both sides and pressed under vacuum conditions of 380-390℃, 3-4h, and 3-5MPa to obtain a flexible high-frequency copper-clad laminate. The thermoplastic resin composition comprises, by weight, the following components: 25-35 parts of polytetrafluoroethylene emulsion; 50-65 parts of perfluoroalkoxy vinyl ether polymer; 10-15 parts of ternary copolymer polycarbonate; wherein the ternary copolymer polycarbonate is synthesized by isosorbide, diphenyl carbonate and 1,4-cyclohexanediethanol via melt transesterification. 5-10 parts of coupling agent; 3-5 parts of pH adjuster.

2. The method for manufacturing a flexible high-frequency copper-clad laminate according to claim 1, characterized in that, The polytetrafluoroethylene emulsion in the thermoplastic resin composition is a dispersion concentrate of polytetrafluoroethylene after polymerization in the presence of a nonionic surfactant, with a solid content of 60% and a pH value of 9-10.

3. The method for manufacturing a flexible high-frequency copper-clad laminate according to claim 1, characterized in that, The coupling agent in the thermoplastic resin composition is an aminosilane coupling agent.

4. The method for manufacturing a flexible high-frequency copper-clad laminate according to claim 1, characterized in that, The pH adjuster in the thermoplastic resin composition is ammonia.

5. A flexible high-frequency copper-clad laminate manufactured by the method according to any one of claims 1 to 4.

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