A modified liquid crystal polymer composition, a copper clad laminate and a preparation method thereof

Abstract

The present invention discloses a modified liquid crystal polymer composition, a copper clad laminate and a preparation method thereof, belonging to the technical field of liquid crystal polymers. Among them, the modified liquid crystal polymer composition includes a liquid crystal polymer resin, a modified additive, a lubricant and / or an antioxidant; the mass ratio of the liquid crystal polymer resin to the modified additive is (80~99):(1~20). By adding a modified additive to the liquid crystal polymer resin, the present invention improves the wettability between the modified liquid crystal polymer film and the copper foil, enhances the bonding force between the modified liquid crystal polymer film and the copper foil, and enables the copper clad laminate to have excellent peel strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal polymers, and particularly relates to a modified liquid crystal polymer composition, a copper clad laminate and a preparation method thereof. Background Art

[0002] With the rapid development of 5G technology, the application requirements of high frequency and high speed put forward higher requirements for the transmission loss of materials, which promotes the accelerated development of high frequency application technology. At the same time, the expansion and strengthening of the functions of application products, such as photography, Bluetooth, Wi-Fi, 5G Internet access, fingerprint identification and wireless charging devices, etc., require more and more functions to be integrated together. This makes the design of high-speed and high-frequency substrate materials, namely flexible copper clad laminates, which are responsible for signal transmission functions, tend to be high-precision and high-density, and at the same time, the demand for flexible copper clad laminates is increasing day by day.

[0003] Flexible copper clad laminate (FCCL) is a polymer composite substrate covered with single or multiple layers of wiring. Currently, the medium and high frequency FCCLs widely used in the industry are mainly polyimide (PI) flexible copper clad laminates (PI-FCCL). However, the dielectric constant of PI is relatively high (dielectric constant ≥ 3.4), which cannot meet the requirements of 5G high-frequency communication for the dielectric properties of dielectrics (dielectric constant < 3.0). At the same time, PI has strong water absorption, which will further damage its dielectric properties. In addition, the coefficient of thermal expansion of PI (CTE ≥ 70 ppm / K) is higher than that of copper foil (CTE = 22 ppm / K), resulting in phenomena such as wrinkles, fractures, and delaminations in the PI layer of the copper clad laminate in the environment of alternating hot and cold use. Even modified polyimide (MPI) flexible copper clad laminate (MPI-FCCL) cannot completely overcome these problems, so it shows deficiencies in 5G communication applications.

[0004] Liquid crystal polymer (LCP) has high heat resistance, low water absorption, low dielectric loss and high dimensional stability, and has received extensive attention in high-frequency circuit substrates or circuits for high-speed transmission lines in recent years, and is considered to be an ideal material for 5G high-frequency signal transmission. Compared with traditional PI films, LCP has many advantages as a copper clad laminate substrate. First of all, LCP has excellent dielectric properties, with low dielectric constant and dielectric loss, which makes LCP-FCCL have lower signal loss during high-frequency signal transmission, and is particularly suitable for high-frequency application scenarios such as 5G communication. Secondly, LCP shows excellent thermal stability and dimensional stability, and has a small coefficient of thermal expansion, which helps to improve the reliability of electronic products. In addition, LCP also has excellent chemical resistance and moisture resistance, and can maintain stable performance in harsh environments. Finally, LCP has a low density, which helps to achieve lightweight design of electronic products. These advantages make the application prospect of LCP-FCCL in high-end electronic products broad.

[0005] Currently, there are mainly two methods for preparing LCP-FCCL: The first is the coating method, which directly coats the LCP resin on the copper foil; the second is to make the LCP resin into a film and then attach it to the copper foil by lamination. As one of the main methods for producing LCP-FCCL, the coating method has some significant technical limitations. First, it is difficult to ensure the uniformity of the coating during the coating process, which may lead to uneven thickness of the LCP layer, affecting the electrical performance and mechanical strength of the product. In addition, the parameters of the coating process (such as coating speed, temperature, drying time, etc.) need to be precisely controlled, which not only increases the complexity of the production process but also may affect the yield of the product. The advantage of the lamination method is that it can precisely control the thickness of the film and optimize the bonding between the LCP and the copper foil by adjusting the lamination temperature and pressure. However, there are certain differences in the interfacial adhesion between the LCP and the copper foil, and improving the bonding strength between the two is an important research topic.

[0006] The traditional way to improve the copper-clad bonding strength is generally to roughen the metal layer, that is, to increase the surface roughness of the copper foil, and enhance the bonding strength between the polymer substrate and the copper foil through the anchoring effect. However, this will result in poor uniformity of the peel strength in the plane of the copper-clad board, and at the same time, it is easy to generate the skin effect, weakening the high-frequency performance of the liquid crystal polymer film.

[0007] In addition, there is another method, which is to perform surface treatment on the liquid crystal polymer film. For example, Patent US20140023881A1 discloses a method for manufacturing a copper-clad laminate of a liquid crystal polymer film, which uses plasma to treat the surface of the liquid crystal polymer film, and then makes the treated liquid crystal polymer film into a copper-clad laminate. Patent CN111901977A discloses a method for preparing a copper-clad laminate of a liquid crystal polymer film, which performs plasma activation treatment on the liquid crystal polymer film, deposits copper on the surface of the treated film, and then continuously electroplates copper on the obtained copper layer to obtain a copper-clad laminate of the liquid crystal polymer film. The disadvantage of this method is that surface treatment usually has timeliness, and the treated liquid crystal polymer film must be copper-clad immediately, otherwise the activation effect will decay or even fail. Summary of the Invention

[0008] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a modified liquid crystal polymer composition, a copper-clad laminate and its preparation method. By adding a modified additive to the liquid crystal polymer resin, the wettability between the modified liquid crystal polymer film and the copper foil is improved, the bonding strength between the modified liquid crystal polymer film and the copper foil is enhanced, and the copper-clad laminate has excellent peel strength.

[0009] The present invention provides the following technical solutions:

[0010] In the first aspect, a modified liquid crystal polymer composition is provided, which includes a liquid crystal polymer resin, a modified additive, a lubricant and / or an antioxidant;

[0011] The mass ratio of the liquid crystal polymer resin to the modified additive is (80~99):(1~20);

[0012] The modified additive is selected from one or a combination of polyolefin elastomer (POE), tackifying resin, ethylene-vinyl acetate copolymer (EVA), and poly(ethylene succinate) (PES) copolyester.

[0013] Furthermore, the modified liquid crystal polymer composition comprises the following components in parts by mass: 90~99 parts of liquid crystal polymer resin, 1~10 parts of modified additive, 0.1~1 part of lubricant, and 0.01~0.5 part of antioxidant.

[0014] Furthermore, the liquid crystal polymer resin is selected from film-grade resins with a melting point greater than or equal to 280 °C.

[0015] Furthermore, the lubricant is selected from one or a combination of stearic acid lubricants, stearyl alcohol lubricants, and stearic acid ester lubricants. The addition of the lubricant can improve the heat generation due to internal friction of the liquid crystal polymer resin melt and the fluidity of the modified additive melt, and reduce thermal degradation.

[0016] Furthermore, the lubricant is selected from one or a combination of magnesium stearate, zinc stearate, glycerol monostearate, and pentaerythritol stearate.

[0017] Furthermore, the lubricant is preferably glycerol monostearate.

[0018] Furthermore, the antioxidant is selected from a compound of one or more of antioxidant 168, antioxidant 246, and antioxidant 1010.

[0019] Furthermore, the antioxidant is preferably a compound of antioxidant 168 and antioxidant 1010.

[0020] In a second aspect, a method for preparing a copper clad laminate is provided, comprising the following steps:

[0021] Place the components of the modified liquid crystal polymer composition described in the first aspect in a mixer for mixing, and put the mixed raw materials into a twin-screw extruder, and obtain a modified liquid crystal polymer composition through melting, blending, extrusion, and pelletizing;

[0022] Put the modified liquid crystal polymer composition into a single-screw extruder, and obtain a modified liquid crystal polymer film through extrusion casting or extrusion blowing;

[0023] Pull the modified liquid crystal polymer film to a pressure roller for lamination with copper foil to obtain a copper clad laminate.

[0024] Further, the rotational speed of the twin-screw extruder is 200 - 500 rpm / min, and the temperature is Tm + 10°C to Tm + 20°C, where Tm is the melting point of the liquid crystal polymer resin.

[0025] Further, when using a single-screw extruder for extrusion and blowing film, the temperature is Tm + 10°C to Tm + 20°C, the blow-up ratio is (10:6) - (4:3), and the draw ratio is (2:1) - (5:1).

[0026] Further, when the modified liquid crystal polymer film is drawn to be compounded with the copper foil by the pressure roller, the pressure is 0.2 - 2 MPa, and the temperature is Tm + 5°C to Tm + 25°C.

[0027] In a third aspect, a copper-clad laminate prepared by the method described in the second aspect is provided.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The modified liquid crystal polymer composition provided by the present invention includes a liquid crystal polymer resin, a modified additive, a lubricant, and / or an antioxidant. The liquid crystal polymer resin is modified by the modified additive, so that the prepared modified liquid crystal polymer composition has a lower viscosity and a higher creep compliance. After the modified liquid crystal polymer composition is made into a modified liquid crystal polymer film and laminated with the copper foil, the wettability between the modified liquid crystal polymer film and the copper foil is good, and the bonding strength is strong, so that the obtained flexible copper-clad laminate has excellent peel strength. Further, by adjusting the addition amount of the modified additive within the scope defined by the present invention (the mass ratio of the liquid crystal polymer resin to the modified additive is (80 - 99):(1 - 20)), the peel strength can be adjusted to the required strength. However, too little modified additive has an insignificant effect on improving the peel strength, and too much modified additive will migrate to the surface of the modified liquid crystal polymer composition during the cooling and curing process, greatly reducing its surface tension and significantly reducing its peel strength. Description of the Drawings

[0030] Figure 1 It is a complex viscosity diagram of the modified liquid crystal polymer composition in the examples and comparative examples of the present invention;

[0031] Figure 2 It is a creep compliance diagram of the modified liquid crystal polymer composition in the examples and comparative examples of the present invention;

[0032] Figure 3 It is a diagram of the flexible copper-clad laminate test sample in Example 1 of the present invention after the peel strength test;

[0033] Figure 4 It is a diagram of the flexible copper-clad laminate test sample in Example 2 of the present invention after the peel strength test;

[0034] Figure 5 This is the figure after the peel strength test of the flexible copper clad laminate test sample in Example 4 of the present invention;

[0035] Figure 6 This is the figure after the peel strength test of the flexible copper clad laminate test sample in Comparative Example 1 of the present invention. Detailed implementation manners

[0036] The present invention will be further described below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0037] The manufacturer and brand information of the raw materials used in the following examples are as follows:

[0038] Liquid crystal polymer resin, manufactured by Polyplastics Co., Ltd. of Japan, brand A950RX;

[0039] Polyolefin elastomer, manufactured by ExxonMobil, brand POE-8880;

[0040] Tackifying resin, manufactured by ExxonMobil, brand Escorez-5637;

[0041] Ethylene-vinyl acetate copolymer, manufactured by Unitika Ltd. of Japan, brand DQDJ-1868;

[0042] Polyethylene glycol succinate copolyester, manufactured by Shanghai Aladdin;

[0043] Lubricant, glycerol monostearate, manufactured by Shanghai Kaisai Chemical Industry;

[0044] Antioxidant, manufactured by Sinopharm Chemical Reagent Co., Ltd., brands 168 and 1010.

[0045] Example 1

[0046] (1) Prepare the modified liquid crystal polymer composition according to the following components in parts by mass: 98 parts of liquid crystal polymer resin, 2 parts of polyolefin elastomer, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0047] (2) Place the raw material components in step (1) in an oven at 140 °C for 5 h to remove moisture, and then put the dried raw materials into a high-speed mixer and mix at high speed for 5 min; then put the mixed raw materials into a twin-screw extruder. The rotational speed of the twin-screw extruder is 500 rpm / min, and the temperature is 290-300 °C. After melting, blending, extrusion, and pelletizing, a modified liquid crystal polymer composition is obtained.

[0048] (3) The modified liquid crystal polymer composition is put into a single-screw extruder, and a modified liquid crystal polymer film is obtained by extrusion blow molding. In the blow molding process, the temperature is 290 - 300 °C, the blow-up ratio is 6:4, and the draw ratio is 3:1. The thickness of the obtained modified liquid crystal polymer film is 50 μm.

[0049] (4) The modified liquid crystal polymer film is drawn to be compounded with copper foil by a pressure roller. The thickness of the copper foil is 50 μm, the compounding temperature is 290 °C, and the pressure is 1.0 MPa to form a flexible copper clad laminate.

[0050] Example 2

[0051] The difference between this example and Example 1 is that in step (1), the modified liquid crystal polymer composition is prepared with the following components in parts by mass: 95 parts of liquid crystal polymer resin, 5 parts of polyolefin elastomer, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0052] Example 3

[0053] The difference between this example and Example 1 is that in step (1), the modified liquid crystal polymer composition is prepared with the following components in parts by mass: 98 parts of liquid crystal polymer resin, 2 parts of tackifying resin, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0054] Example 4

[0055] The difference between this example and Example 1 is that in step (1), the modified liquid crystal polymer composition is prepared with the following components in parts by mass: 95 parts of liquid crystal polymer resin, 5 parts of tackifying resin, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0056] Example 5

[0057] The difference between this example and Example 1 is that in step (1), the modified liquid crystal polymer composition is prepared with the following components in parts by mass: 95 parts of liquid crystal polymer resin, 5 parts of ethylene-vinyl acetate copolymer, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0058] Example 6

[0059] The difference between this example and Example 1 is that in step (1), the modified liquid crystal polymer composition is prepared with the following components in parts by mass: 95 parts of liquid crystal polymer resin, 5 parts of polyethylene glycol succinate copolyester powder, 0.2 part of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that in step (1), the modified liquid crystal polymer composition was prepared with the following components by mass: 100 parts of liquid crystal polymer resin, 0.2 parts of glycerol monostearate, 0.1 part of antioxidant 168, and 0.1 part of antioxidant 1010.

[0062] Performance Test

[0063] (1) Melt flow rate test: The test was carried out with reference to GB / T 3682.2 - 2018. The modified liquid crystal polymer compositions prepared in Examples 1 to 6 and Comparative Example 1 were dried at 150°C for 5 h, then placed on a melt flow rate tester, pre-melted at 290°C for 3 min, and then tested under a load of 2.16 kg. The test results are shown in Table 1.

[0064] Table 1 Melt flow rate test results of the modified liquid crystal polymer compositions of the examples and comparative examples

[0065]

[0066] (2) Complex viscosity test: The test was carried out with reference to GB / T 33061. The modified liquid crystal polymer compositions prepared in Examples 1 to 6 and Comparative Example 1 were dried at 150°C for 5 h, then placed on a rotational rheometer, pre-melted at 295°C for 3 min, and then the complex viscosity in the range of 50 - 0.01 Hz was tested in the frequency sweep mode. The results are as Figure 1 shown.

[0067] (3) Creep compliance test: The test was carried out with reference to GB / T 33061. The modified liquid crystal polymer compositions prepared in Examples 1 to 6 and Comparative Example 1 were dried at 150°C for 5 h, then placed on a rotational rheometer, pre-melted at 295°C for 3 min, and then the creep compliance was tested in the creep mode. The test stress was 1 kPa and the test time was 5 min. The results are as Figure 2 shown.

[0068] (4) Peel strength test: Tested in accordance with the test method of IPC-TM-6502.4.8. Use the flexible copper clad laminate prepared in Examples 1 to 6 and Comparative Example 1 to make a peel test sample with a width of 1 mm. At room temperature, peel off the bonding surface of the liquid crystal polymer film layer and the copper foil layer from the edge, fix the copper foil layer on the flat plate with double-sided tape, and peel off the liquid crystal polymer film layer in a 180° direction at a speed of 50 mm / min. Use a tensile testing machine to record the peel load. Take the sample with a peel length greater than 100 mm as the valid sample, and calculate the peel strength based on the average value of the load during the peeling process. The test results are shown in Table 2. The states of the test samples of Example 1, Example 2, Example 4 and Comparative Example 1 after the peel strength test are as follows: Figure 3 , Figure 4 , Figure 5 and Figure 6 shown.

[0069] Table 2 Peel strength test results of modified liquid crystal polymer films of the embodiments and comparative examples

[0070]

[0071] like Figure 1 As shown in Table 1, from the comparison between Examples 1 to 6 and Comparative Example 1, it can be seen that the technical solution provided by the present invention can effectively improve the melt index of the resin and reduce the viscosity of the resin by adding an appropriate amount of modifying additives to the liquid crystal polymer.

[0072] like Figure 2 As shown, by comparing Examples 1 to 6 with Comparative Example 1, it can be seen that the technical solution provided by the present invention can simultaneously improve the creep compliance of the resin by adding an appropriate amount of modifying additives to the liquid crystal polymer, thereby improving the wetting performance with the copper foil.

[0073] As shown in Table 2 and Figures 3 to 6 As shown, by comparing Examples 1 to 6 with Comparative Example 1, it can be seen that the technical solution provided by the present invention effectively improves the peel strength between the liquid crystal polymer film layer and the copper foil layer, that is, enhances the bonding force between the liquid crystal polymer film and the copper foil, so that the flexible copper clad laminate has excellent peel strength.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A modified liquid crystal polymer composition, characterized in that, It comprises the following components in parts by mass: 90 - 99 parts of liquid crystal polymer resin, 1 - 10 parts of modified additive, 0.1 - 1 part of lubricant, and 0.01 - 0.5 part of antioxidant; The modified additive is selected from one or a combination of tackifying resins, polyethylene glycol succinate copolyesters, etc.; The modified liquid crystal polymer composition is used to prepare a modified liquid crystal polymer film, which is compounded with copper foil to prepare a copper clad laminate.

2. The modified liquid crystal polymer composition according to claim 1, wherein The liquid crystal polymer resin is selected from film - grade resins with a melting point greater than or equal to 280 °C.

3. The modified liquid crystal polymer composition according to claim 1, characterized in that, The lubricant is selected from one or a combination of stearic acid - based lubricants, stearyl alcohol - based lubricants, stearic acid ester - based lubricants, etc.

4. The modified liquid crystal polymer composition according to claim 1, wherein The antioxidant is selected from a compounding of one or more of antioxidant 168, antioxidant 246, and antioxidant 1010.

5. A method for preparing a copper clad laminate, characterized in that, It includes the following steps: Place the components of the modified liquid crystal polymer composition according to any one of claims 1 - 4 in a mixer for mixing. The mixed raw materials are put into a twin - screw extruder, and after melting, blending, extrusion, and pelletizing, a modified liquid crystal polymer composition is obtained; Put the modified liquid crystal polymer composition into a single - screw extruder, and through extrusion casting or extrusion blowing, a modified liquid crystal polymer film is obtained; Pull the modified liquid crystal polymer film to a pressure roller for compounding with copper foil to obtain a copper clad laminate.

6. The method for preparing a copper clad laminate according to claim 5, wherein The rotational speed of the twin - screw extruder is 200 - 500 rpm / min, and the temperature is Tm + 10 °C - Tm + 20 °C, where Tm is the melting point of the liquid crystal polymer resin.

7. The method for preparing a copper clad laminate according to claim 5, wherein, When using a single - screw extruder for extrusion blowing, the temperature is Tm + 10 °C - Tm + 20 °C, the blow - up ratio is (10:6) - (4:3), and the draw ratio is (2:1) - (5:1).

8. The manufacturing method of the copper clad laminate according to claim 5, wherein, When the modified liquid crystal polymer film is pulled to a pressure roller for compounding with copper foil, the pressure is 0.2 - 2 MPa, and the temperature is Tm + 5 °C - Tm + 25 °C, where Tm is the melting point of the liquid crystal polymer resin.

9. A copper clad laminate prepared by the method according to any one of claims 5 - 8.

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