LCP thin film and preparation method therefor

Abstract

An LCP thin film and a preparation method therefor. The preparation method comprises the following steps: performing melt extrusion and film blowing on LCP to obtain a thin film, compounding the thin film by means of a support body, and performing heat treatment to obtain an LCP thin film, wherein a heat treatment temperature ranges from 150°C to the melting point of an LCP resin, and the treatment time ranges from 1 min to 30 min. The LCP thin film has high tear strength, thereby improving the processing stability of the LCP thin film in the application process; and the LCP thin film has excellent dimensional stability and good thickness uniformity, thereby preventing the occurrence of bubbles during press-fit of the LCP thin film. The LCP thin film further has excellent dimensional stability and good bonding strength with a copper foil, thereby preventing the copper foil from being separated from the LCP thin film during press-fit of the LCP thin film and the copper foil at a high temperature.

Description

A LCP film and its preparation method Technical Field

[0001] The present invention relates to the technical field of B29D7 / 00, and in particular to an LCP film and a preparation method thereof. Background Art

[0002] LCP is a thermotropic liquid crystal polymer, a high-performance polymer material with excellent modulus, strength, barrier properties and other properties. Due to its low dielectric constant, its processed products will be used in the field of electronic communications. The molecular structure of LCP is a rigid chain segment, which is in a liquid crystal state in the molten state and has excellent fluidity, but it also has anisotropic defects, and has high requirements for processing technology. The LCP film obtained by stretching or extrusion blow molding has great rigidity, resulting in a low pass rate and low output of the LCP film. In addition, the LCP film after film formation has poor bonding with the metal foil. There are also bubbles when it is pressed with the metal foil during application, and the copper foil and LCP film will separate during high-temperature processing, which reduces the processing stability of the LCP film during application and further affects the bending resistance of the LCP film after being processed into electronic products. Due to the existence of the above problems, the LCP film is difficult to apply in the back end.

[0003] The Chinese patent application number CN202011207859.1 discloses a method for preparing a tear-resistant, low-anisotropy liquid crystal polyester film. The temperature difference between the two rollers and the melting point of the liquid crystal polyester is used to make one side of the prepared liquid crystal polyester paper maintain high-order crystallization, thereby improving the tear strength of the liquid crystal polyester paper, while the other side retains the liquid crystal polyester paper with low anisotropy caused by the disordered liquid crystal polyester fibers in the liquid crystal polyester film, thereby obtaining a liquid crystal polyester film that meets both low anisotropy and high tear strength. The film can be directly used in circuit boards, reducing the manufacturing process of circuit boards; however, this patented technology does not provide solutions to problems such as reducing the occurrence of bubbles when the LCP film is pressed with metal foil during application, avoiding the separation of copper foil and LCP film during high-temperature processing, and improving the bending resistance of the LCP film after being processed into electronic products.

[0004] Therefore, the main technical problems that need to be solved at present are to provide a treatment method that can solve the problems of poor bonding between LCP film and metal foil, reduce the appearance of bubbles when LCP film is pressed with metal foil during application, avoid the separation of copper foil and LCP film during high-temperature processing, and improve the bending resistance of LCP film after being processed into electronic products.

[0005] Summary of the Invention

[0006] In order to solve the above problems, the first aspect of the present invention provides a method for preparing an LCP film, comprising the following steps: subjecting the LCP to melt extrusion and film blowing to obtain a film a, and then laminating the film a with a support and heat treating the film to obtain an LCP film; the heat treatment temperature is 150°C to the melting point of the LCP resin, and the treatment time is 1 to 30 minutes;

[0007] The ratio of the tensile strength of the LCP film in the MD direction to the TD direction (MD / TD) is 0.6 to 4;

[0008] The ratio of the elongation at break of the LCP film in the MD direction to the TD direction (MD / TD) is 0.4 to 2.5;

[0009] The dimensional stability of the LCP film in the MD direction is -0.1% to 0.1%, and the dimensional stability of the LCP film in the TD direction is -0.2% to 0.2%;

[0010] The thickness of the LCP film is ≥15 μm.

[0011] In one embodiment, the thickness of the film a is consistent with the thickness of the prepared LCP film.

[0012] The MD direction is the machine direction, length direction, and longitudinal direction of the film.

[0013] The TD direction is the width direction or transverse direction of the film.

[0014] In order to avoid the problem of LCP film separating from copper foil at high temperature during application, the inventor creatively discovered during the experiment that the heat treatment of LCP film should not be too long. When the heating time exceeds 30 minutes, the tensile strength of the LCP film in the MD or TD direction will be reduced, and the dimensional stability of the LCP film will be reduced, which will further affect the bonding strength between the LCP film and the copper foil, causing the LCP film to separate from the copper foil at high temperature during application. The possible reason is that as the heat treatment time increases, the arrangement time of molecular chain segments in different directions in the LCP film will also increase, increasing the probability of unstable arrangement of molecular chain segments, resulting in reduced tensile strength, tear strength and dimensional stability of the LCP film, and the problem of LCP film and copper foil separation at high temperature.

[0015] In one embodiment, the melt viscosity of the LCP is ≥30 Pa·s.

[0016] In one embodiment, the LCP has a melting point of 270-330°C.

[0017] Furthermore, the melting point of the LCP may be 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, or 330°C.

[0018] The melting point is determined according to the test standard GB / T 19466.3-2004, specifically the secondary heating melting peak temperature.

[0019] The viscosity test standard is GB / T 25278-2010, using a die with an inner diameter of 0.5 mm, at 20°C above the melt temperature and for 1000 seconds. -1 The melt viscosity is measured by a capillary rheometer at a shear rate of 1.

[0020] In one embodiment, the LCP has a melting point of 280°C, 310°C, or 330°C.

[0021] In one embodiment, the melt viscosity of the LCP is 35-45 Pa·s, the melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX from Japan.

[0022] In one embodiment, the melt viscosity of the LCP is 40-50 Pa·s, the melting point of the LCP is 280° C., and the manufacturer model of the LCP is Polyplastics A950RX from Japan.

[0023] In one embodiment, the melting point of the LCP is 310° C., and the manufacturer model of the LCP is A310 from Shanghai Pulite Composite Materials Co., Ltd.

[0024] In one embodiment, the step of laminating the film a with a support is to use a metal foil as a support and press the metal foil with the film a to obtain a film a metal foil laminate.

[0025] In one embodiment, the film a is laminated with a metal foil by a double-sided lamination process or a single-sided lamination process to obtain a film a metal foil laminate, which is then heat treated.

[0026] The double-sided lamination process uses film a as the middle layer, covers the upper and lower sides with metal foil, and uses a heated roller calender to press.

[0027] The single-sided lamination process: one side of the film a is covered with metal foil and pressed using a heated roller calender.

[0028] In order to avoid the problem of bubbles appearing when the LCP film is pressed against the metal foil during the application process, the inventor creatively discovered during the experiment that the heat treatment temperature of the LCP film cannot be too high. When the heat treatment temperature exceeds the melting point of the LCP resin, the thickness uniformity of the LCP film will be reduced, resulting in bubbles appearing when the LCP film is pressed against the metal foil during the application process. The possible reason is that when the LCP film is heated at a higher temperature in a short period of time, the scale for adjusting the arrangement of molecular chain segments in different directions in the LCP film will become larger, resulting in anisotropic differences in the density of the molecular chain segment arrangement, which will deteriorate the microscopic thickness uniformity of the LCP film, resulting in bubbles appearing when the LCP film is pressed against the metal foil during the application process.

[0029] In one embodiment, the heat treatment is performed by increasing the temperature in a gradient manner.

[0030] In one embodiment, the gradient heating method includes heating from 150° C. to the melting point of the LCP resin at a heating rate of 100° C. / min.

[0031] In one embodiment, the gradient heating method includes multi-stage heating; the multi-stage heating includes heating from 150°C to 240°C at a heating rate of 100°C / min, and then heating from 240°C to the melting point of the LCP resin at a heating rate of 5-30°C / min.

[0032] In order to improve the bonding properties and enhance the bonding strength between the LCP film and the metal foil, the inventors creatively discovered during experiments that when the heating temperature of the LCP film obtained by heat treatment is increased from 150°C to the melting point of the LCP resin, and a gradient heating treatment method is used, the dimensional stability of the LCP film, the tear strength of the LCP film, and the bonding strength between the LCP film and the metal foil can be improved. The possible reason is that surface heat treatment of the LCP film, especially a short-term gradient heating treatment, can adjust the ordering of the molecular chain segments in different directions in the LCP film, so that the LCP film maintains anisotropic dimensional stability during subsequent applications. By adjusting the ordering of the molecular chain segments in different directions, the tear strength of the LCP film can be improved, and the bonding strength between the LCP film and the metal foil can be further improved. When the heating temperature of the LCP film is lower than 150°C, the ordering of the molecular chain segments in different directions in the LCP film cannot be effectively adjusted, and defects in the anisotropic direction will exist, which reduces the dimensional stability, elongation at break, and tear strength of the LCP film, and further reduces the bonding strength between the LCP film and the metal foil.

[0033] In one embodiment, the LCP film has a thickness of 15 to 150 μm.

[0034] In one embodiment, the LCP film has a thickness of 25 μm.

[0035] In one embodiment, the method for preparing the LCP film comprises the following steps:

[0036] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0037] S2: Laminating the films by laminating: Using a metal foil as a support, laminating the film a with the metal foil by a double-sided lamination process or a single-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 150-220°C;

[0038] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150° C. to the melting point of the LCP resin at a heating rate of 100° C. / min.

[0039] In one embodiment, the method for preparing the LCP film comprises the following steps:

[0040] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0041] S2: Laminating the films by laminating: Using a metal foil as a support, laminating the film a with the metal foil by a double-sided lamination process or a single-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 150-220°C;

[0042] S3: Heat treatment to obtain LCP film: heat treatment is performed using a gradient heating method, wherein the gradient heating method is to heat from 150°C to 240°C at a heating rate of 100°C / min, and then to heat from 240°C to the melting point of the LCP resin at a heating rate of 5-30°C / min.

[0043] In one embodiment, in S2, the films are laminated at a lamination temperature of 200°C.

[0044] In order to improve the excellent bending resistance of LCP film in back-end applications, the inventor creatively discovered during the experiment that the time for heat treatment of LCP film using a gradient heating method is 1 to 30 minutes, and when the heating temperature is increased from 150°C to the melting point of LCP resin, the excellent bending resistance of LCP film in back-end applications can be improved, but the treatment time cannot be too short. The possible reason is that when the treatment time is too short, it will affect the regularity of the molecular chain structure in the LCP film to adjust in a short time, increase the rigidity of the LCP film, reduce the tear strength of the LCP film, and also cause a decrease in the elongation at break, further reducing the excellent bending resistance of the LCP film in back-end applications.

[0045] A second aspect of the present invention provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0046] In one embodiment, the peel strength between the LCP film and the copper foil is greater than 0.5 N / mm; the roughness of the copper foil is 0.5-20 μm, and the thickness of the copper foil is 9-35 μm.

[0047] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0048] 1. The LCP film provided by the present invention has good bonding strength with copper foil during high-temperature processing, and further improves the stability of the LCP film during application.

[0049] 2. The LCP film provided by the present invention has high tear strength, which improves the processing stability of the LCP film during application.

[0050] 3. The LCP film provided by the present invention has excellent dimensional stability and good uniformity in thickness, which avoids the formation of bubbles in the LCP film during the lamination process of application.

[0051] 4. The LCP film provided by the present invention has excellent dimensional stability and good bonding strength with the copper foil, thereby avoiding the phenomenon of separation of the copper foil and the LCP film when the LCP film is pressed against the copper foil at high temperature.

[0052] 5. The LCP film provided by the present invention has high elongation at break and tear strength, which improves the bending resistance of LCP film processed into flexible copper-clad laminates and flexible circuit board products. DETAILED DESCRIPTION

[0053] Example 1

[0054] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0055] S1: LCP is melt-extruded, and the melt passes through an annular die to obtain film a using a blown film method;

[0056] S2: Laminating the films by laminating: Using metal foil as a support, laminating film a with the metal foil by a single-sided lamination process to obtain a film a-metal foil laminate at a lamination temperature of 200°C;

[0057] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150° C. to 330° C. at a heating rate of 100° C. / min.

[0058] The melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX of Japan.

[0059] The thickness of the LCP film is 25 μm.

[0060] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0061] Example 2

[0062] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0063] S1: LCP is melt-extruded, and the melt passes through an annular die to obtain film a using a blown film method;

[0064] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0065] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150° C. to 330° C. at a heating rate of 100° C. / min.

[0066] The melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX of Japan.

[0067] The thickness of the LCP film is 25 μm.

[0068] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0069] Example 3

[0070] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0071] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0072] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0073] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 330°C at a temperature increase rate of 5°C / min.

[0074] The melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX of Japan.

[0075] The thickness of the LCP film is 25 μm.

[0076] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0077] Example 4

[0078] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0079] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0080] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0081] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 330°C at a temperature increase rate of 30°C / min.

[0082] The melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX of Japan.

[0083] The thickness of the LCP film is 25 μm.

[0084] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0085] Example 5

[0086] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0087] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0088] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0089] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 330°C at a temperature increase rate of 20°C / min.

[0090] The melting point of the LCP is 330° C., and the manufacturer model of the LCP is Polyplastics C950RX of Japan.

[0091] The thickness of the LCP film is 25 μm.

[0092] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0093] Example 6

[0094] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0095] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0096] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0097] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 280°C at a temperature increase rate of 20°C / min.

[0098] The melting point of the LCP is 280° C., and the manufacturer model of the LCP is Polyplastics A950RX from Japan.

[0099] The thickness of the LCP film is 25 μm.

[0100] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0101] Example 7

[0102] A first aspect of the present embodiment provides a method for preparing an LCP film, comprising the following steps:

[0103] S1: The LCP is melt-extruded, and the melt passes through an annular die to obtain a film a using a blown film method;

[0104] S2: Laminating the films by laminating: using metal foil as a support, laminating film a with the metal foil by double-sided lamination process to obtain a film a-metal foil laminate, at a lamination temperature of 200°C;

[0105] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 310°C at a temperature increase rate of 20°C / min.

[0106] The melting point of the LCP is 310° C., and the manufacturer model of the LCP is A310, which is purchased from Shanghai Pulite Composite Materials Co., Ltd.

[0107] The thickness of the LCP film is 25 μm.

[0108] A second aspect of this embodiment provides an LCP film, which is prepared by the above-mentioned method for preparing the LCP film.

[0109] Comparative Example 1

[0110] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 5. The differences between this comparative example and Example 5 are as follows:

[0111] S3: heat treatment to obtain an LCP film: the heat treatment adopts constant temperature heating treatment, the heating temperature is 140° C., and the treatment time is 2 minutes.

[0112] The thickness of the LCP film is 25 μm.

[0113] Comparative Example 2

[0114] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 5. The differences between this comparative example and Example 5 are as follows:

[0115] S3: heat treatment to obtain an LCP film: the heat treatment adopts constant temperature heating treatment, the heating temperature of the heat treatment is 330° C., and the treatment time is 10 s.

[0116] The thickness of the LCP film is 25 μm.

[0117] Comparative Example 3

[0118] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 5. The differences between this comparative example and Example 5 are as follows:

[0119] S3: Heat treatment to obtain an LCP film: the initial heating temperature of the heat treatment is 150° C., the final heating temperature is 330° C., and the temperature is increased at a heating rate of 200° C. / min.

[0120] The thickness of the LCP film is 25 μm.

[0121] Comparative Example 4

[0122] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 5. The differences between this comparative example and Example 5 are as follows:

[0123] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 330°C at a temperature increase rate of 2°C / min.

[0124] The thickness of the LCP film is 25 μm.

[0125] Comparative Example 5

[0126] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 6. The differences between this comparative example and Example 6 are as follows:

[0127] S3: heat treatment to obtain an LCP film, wherein the heat treatment adopts constant temperature heating treatment, the heating temperature of the heat treatment is 140° C., and the treatment time is 1.5 minutes.

[0128] The thickness of the LCP film is 25 μm.

[0129] Comparative Example 6

[0130] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 6. The differences between this comparative example and Example 6 are as follows:

[0131] S3: Heat treatment to obtain an LCP film: the initial heating temperature of the heat treatment is 150° C., the final heating temperature is 285° C., and the temperature is increased at a heating rate of 200° C. / min.

[0132] The thickness of the LCP film is 25 μm.

[0133] Comparative Example 7

[0134] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 7. The differences between this comparative example and Example 7 are as follows:

[0135] S3: Heat treatment to obtain an LCP film: the initial heating temperature of the heat treatment is 150° C., the final heating temperature is 310° C., and the temperature is increased at a heating rate of 200° C. / min.

[0136] The thickness of the LCP film is 25 μm.

[0137] Comparative Example 8

[0138] This comparative example provides a method for preparing an LCP film. The specific implementation method is the same as that of Example 7. The differences between this comparative example and Example 7 are as follows:

[0139] S3: Heat treatment to obtain an LCP film: heat treatment is performed using a gradient temperature increase method, wherein the gradient temperature increase method is to increase the temperature from 150°C to 240°C at a temperature increase rate of 100°C / min, and then to increase the temperature from 240°C to 310°C at a temperature increase rate of 2°C / min.

[0140] The thickness of the LCP film is 25 μm.

[0141] The thickness of the LCP film in this application is measured using a thickness gauge according to ASTM D645.

[0142] Performance testing:

[0143] 1Tensile strength and elongation at break:

[0144] The tensile strength and elongation at break were tested using a film tensile strength tester according to the GB / T 1040.3-2006 method. Ten test samples were taken for each example for testing. The maximum and minimum test results were removed and the average test result was taken. The test results are shown in Table 1.

[0145] 2. Peel strength and separation test of LCP film and copper foil:

[0146] The present invention hot-presses a liquid crystal polyester film and copper foil, and tests the maximum force required to peel the LCP film from the copper foil, i.e., the 90° peel strength, to evaluate the bonding strength between the LCP film and the metal. The test is performed according to ASTM D3330. The hot-pressing temperature is the melting point of the LCP, and the time is 2 minutes. Ten test samples are taken for each example for testing. The maximum and minimum test results are removed, and the average test result is taken. The test results are shown in Table 1. During the hot-pressing process, it is observed whether the LCP film separates from the copper foil. If 9-10 samples do not separate in the test results, the judgment result is A; if 6-8 samples do not separate in the test results, the judgment result is B; if 3-5 samples do not separate in the test results, the judgment result is C; and if 0-2 samples do not separate in the test results, the judgment result is D. The test results are shown in Table 2.

[0147] The surface roughness of the copper foil used is 5 μm, and the thickness of the copper foil is 12 μm.

[0148] 3. Dimensional stability

[0149] Test method: Refer to JIS C6471-1995 9.6 method for testing. Specifically, cut a 240*300mm film, mark 4 points according to the standard requirements, and measure the distance between each point. Then, place the film in a 150℃ oven for 30 minutes, measure the distance between the 4 points again, and calculate the dimensional stability.

[0150] For each example, 10 test samples were tested, the maximum and minimum test results were removed, and the average test result was taken. The test results are shown in Table 1.

[0151] 4. Tear strength

[0152] Test method: The tear strength was tested according to the test method of 2.4.16 of the "Test Method Manual" for initial tear strength of flexible insulating materials, IPC-TM-650 (03 / 14B version); 10 test samples were taken for each embodiment for testing, and the maximum and minimum test results were removed to take the average test result. The test results are shown in Table 1.

[0153] 5. Bubble test

[0154] (1) Observe whether bubbles appear when the LCP film is pressed against the metal foil (copper foil) during the application process. For each embodiment, 10 test samples are taken for testing. If 9-10 samples do not have bubbles, the judgment result is A; if 6-8 samples do not have bubbles, the judgment result is B; if 3-5 samples do not have bubbles, the judgment result is C; if 0-2 samples do not have bubbles, the judgment result is D. The test results are shown in Table 2.

[0155] 6. Bending resistance test

[0156] For each example, 10 test samples were tested, the maximum and minimum test results were removed, and the average test result was taken to test the number of times the LCP film could be bent horizontally and vertically without being damaged. The test results are shown in Table 1.

[0157] Table 1

[0158] Table 2

Claims

1. A preparation method of an LCP film, characterized in that, It includes the following steps: melt-extrusion blow molding LCP to obtain film a, and then compound film a with a support and perform heat treatment to obtain an LCP film; the temperature of the heat treatment is 150°C to the melting point of the LCP resin, and the treatment time is 1 to 30 minutes; The ratio (MD / TD) of the tensile strength of the LCP film in the MD direction and the TD direction is 0.6 to 4; The ratio (MD / TD) of the elongation at break of the LCP film in the MD direction and the TD direction is 0.4 to 2.5; The dimensional stability of the LCP film in the MD direction is -0.1% to 0.1%, and the dimensional stability of the LCP film in the TD direction is -0.2% to 0.2%; The thickness of the LCP film is ≥15 μm.

2. The preparation method of the LCP film according to claim 1, characterized in that, The melt viscosity of the LCP is ≥30 Pa·s.

3. The method for preparing the LCP film according to claim 1, characterized in that, The melting point of the LCP is 270 to 330°C.

4. The preparation method of the LCP film according to claim 1, wherein, Film a is laminated with a metal foil through a double-sided lamination process or a single-sided lamination process to obtain a film a-metal foil laminate, and then heat treatment is performed.

5. The preparation method of the LCP film according to claim 1, wherein, The heat treatment is carried out by a gradient heating method.

6. The method for preparing an LCP film according to claim 5, wherein The gradient heating method includes heating from 150°C to the melting point of the LCP resin at a heating rate of 100°C / min.

7. The preparation method of the LCP film according to claim 5, characterized in that, The gradient heating method includes multi-stage heating; the multi-stage heating includes heating from 150°C to 240°C at a heating rate of 100°C / min, and then heating from 240°C to the melting point of the LCP resin at a heating rate of 5 to 30°C / min.

8. The preparation method of the LCP film according to claim 1, wherein, The thickness of the LCP film is 15 to 150 μm.

9. An LCP film, characterized in that, The LCP film is prepared by the preparation method of the LCP film according to any one of claims 1-8.

10. The LCP film according to claim 9, wherein The peel strength of the LCP film from the copper foil is >0.5 N / mm.

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