A preparation method of a flexible copper clad laminate

Abstract

The present invention relates to a method for preparing a flexible copper clad laminate, comprising the following steps: First, prepare an adhesive, coat the adhesive on a metal foil and bake it to dry on the surface. Then, anneal and preheat a plastic film. Next, laminate the dried adhesive-coated metal foil and the annealed plastic film together, and simultaneously feed them into a pressing wheel for pressing. After pressing, automatically wind it up and cure it to obtain a flexible copper clad laminate. In the present invention, by this method, the prepared flexible copper clad laminate has good dimensional stability, can improve problems such as production wrinkles and appearance abnormalities caused by uneven tension of the plastic film, and at the same time improve warping. Moreover, the process is simple, easy to operate, conducive to improving production efficiency and meeting production requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of copper clad laminates, and particularly to a preparation method of a flexible copper clad laminate. Background Art

[0002] Flexible copper clad laminates generally refer to flexible copper clad laminates, which are widely used in aerospace equipment, navigation equipment, aircraft instruments, military guidance systems, and electronic products such as mobile phones, digital cameras, digital video cameras, automotive satellite orientation devices, liquid crystal TVs, and notebook computers. Due to the rapid development of electronic technology, the demand for and growth trend of flexible copper clad laminates are more prominent, and the production scale is also continuously expanding.

[0003] The existing production process of flexible copper clad laminates is generally as follows: an adhesive is coated on one side or both sides of a plastic film, and after surface drying by high-temperature baking in a tunnel oven, a metal foil is then laminated at high temperature, and post-curing can obtain the product. However, due to the high thermal shrinkage rate of the plastic film itself, the flexible copper clad laminates produced by this process generally have the following problems:

[0004] 1. The dimensional stability of the finished product is poor, which is not conducive to subsequent processing and use, and cannot meet the production requirements;

[0005] 2. The plastic film is prone to expansion when heated and shrinkage when cooled, and tension is applied during the coating process, resulting in warping and uneven appearance after laminating the metal foil;

[0006] 3. The tension of the roll film is uneven, resulting in abnormalities such as wire drawing and wrinkles during glue coating. Summary of the Invention

[0007] Based on this, it is necessary to provide a preparation method of a flexible copper clad laminate for the problems of poor dimensional stability, warping and unevenness, and poor appearance that are likely to occur when producing flexible copper clad laminates by traditional processes in the prior art.

[0008] A preparation method of a flexible copper clad laminate includes the following steps:

[0009] S1. Prepare the adhesive: First, mix rubber, epoxy resin, and an organic solvent, and stir at high speed to promote dissolution; then, add the filler to the mixture, stir and disperse at high speed, and grind the pre-solution so that the filler particle size is less than or equal to 5 μm; finally, add the dissolved curing agent and set aside;

[0010] S2. Feed and coat: Place the metal foil at the first feed end, and adopt an extrusion spraying process to input the adhesive prepared in S1 into the liquid storage and distribution cavity of the coating die head. Through the homogenizing effect of the transverse slit, it spreads in a liquid film shape on the metal foil at the outlet lip, and the coating thickness of the adhesive on the metal foil is 10 μm to 50 μm;

[0011] S3 baking surface dry: through a tunnel-type segmented oven, surface dry, to obtain a surface dry metal foil with a glue layer;

[0012] S4 plastic film annealing send: the plastic film is placed in the second feeding end, sent into the tunnel annealing oven for preheating, to obtain a preheated plastic film;

[0013] S5 Lamination: The metal foil with adhesive layer obtained in S3 and the plastic film obtained in S4 are laminated up and down and fed into the pressing wheel for pressing. After pressing, a semi-finished single-sided flexible copper-clad laminate is obtained;

[0014] S6. Rewinding: Using an automatic rewinder, the semi-finished single-sided flexible copper-clad laminate obtained in S5 is rewound;

[0015] S7. Curing: Place the rolled semi-finished single-sided flexible copper clad laminate in a program-controlled temperature oven and set the program as follows:

[0016] ①Room temperature ~ 60℃, heating time 1h, constant temperature 3h,

[0017] ②60℃~80℃, heating time 1h, constant temperature 4h,

[0018] ③80℃~120℃, heating time 2h, constant temperature 2h,

[0019] ④120℃~160℃, heating time 2h, constant temperature 1h,

[0020] ⑤160℃~room temperature, cool down naturally,

[0021] After cooling, the flexible copper clad laminate is obtained.

[0022] In one embodiment, in the step S2, the sending tension is 30N to 70N, and the line speed is 10m / min to 30m / min.

[0023] In one embodiment, the metal foil is copper foil, and its thickness is 12 μm to 70 μm.

[0024] In one embodiment, in step S3, the tunnel-type segmented oven is divided into six sections, and the length of each section is 4m.

[0025] The temperature of the first section oven is 70℃~80℃, the temperature of the second section oven is 90℃~100℃, the temperature of the third section oven is 110℃~120℃, the temperature of the fourth section oven is 130℃~140℃, the temperature of the fifth section oven is 155℃~165℃, and the temperature of the sixth section oven is 90℃~110℃.

[0026] In one embodiment, in the step S4, the sending tension is 20 N to 40 N, and the wire speed is 10 m / min to 30 m / min.

[0027] In one embodiment, in the step S4, the tunnel annealing oven is divided into four sections, and the length of each section of the oven is 2 m.

[0028] The temperature of the first section of the oven is 100 °C to 120 °C, the temperature of the second section of the oven is 160 °C to 180 °C, the temperature of the third section of the oven is 180 °C to 200 °C, and the temperature of the fourth section of the oven is 100 °C to 120 °C.

[0029] In one embodiment, in the step S5, the temperature of the pressing wheel is 70 °C to 110 °C, and the pressure is 0.1 MPa to 0.6 MPa.

[0030] In one embodiment, in the step S6, the winding tension is 50 N to 70 N.

[0031] The above method for preparing a flexible copper clad laminate makes the obtained flexible copper clad laminate have good dimensional stability, can improve problems such as production wrinkles and appearance abnormalities caused by uneven plastic film tension, and at the same time improve warping. Moreover, the process is simple, easy to operate, conducive to improving production efficiency, and meeting production requirements. Detailed Embodiments

[0032] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description is made of the specific embodiments of the present invention. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] As used herein, the term "prepared from" is synonymous with "comprising". As used herein, the terms "comprising", "including", "having", "containing", or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or device containing the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or elements inherent to such composition, step, method, article, or device.

[0034] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, whether or not that range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, that range is intended to include its end values and all integers and fractions within that range.

[0035] In addition, the indefinite articles "a" and "an" before an element or component of the present invention do not limit the quantity requirement (i.e., the number of occurrences) of the element or component. Therefore, "a" or "an" should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers to the singular form.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] A method for preparing a flexible copper clad laminate, comprising the following steps:

[0038] S1. Prepare the adhesive: First, mix rubber, epoxy resin and an organic solvent, and stir at high speed to promote dissolution; then, add the filler to the mixed solution, stir and disperse at high speed, and grind the pre-solution so that the filler particle size is less than or equal to 5 μm; finally, add the dissolved curing agent and set aside;

[0039] S2. Feeding and coating: Place the metal foil at the first feeding end, and adopt an extrusion spraying process to input the adhesive prepared in S1 into the liquid storage and distribution cavity of the coating die head. Through the homogenizing effect of the transverse slit, it spreads in a liquid film shape onto the metal foil at the outlet lip, and the coating thickness of the adhesive on the metal foil is 10 μm to 50 μm; in the present invention, the metal foil is a copper foil or an aluminum foil, and its thickness is 12 μm to 70 μm;

[0040] S3. Baking to surface dryness: Through a tunnel-type segmented oven, surface drying is carried out to obtain the metal foil with an adhesive layer after surface drying; wherein, the tunnel-type segmented oven is divided into six segments, and the length of each segment of the oven is 4m. Specifically, the temperature of the first segment of the oven is 70°C to 80°C, the temperature of the second segment of the oven is 90°C to 100°C, the temperature of the third segment of the oven is 110°C to 120°C, the temperature of the fourth segment of the oven is 130°C to 140°C, the temperature of the fifth segment of the oven is 155°C to 165°C, and the temperature of the sixth segment of the oven is 90°C to 110°C;

[0041] S4. Annealing and sending of the plastic film: Place the plastic film at the second feeding end and send it into a tunnel-type annealing oven for preheating. During this process, control the sending tension to be 20N to 40N and the linear speed to be 10m / min to 30m / min to obtain the preheated plastic film, and the plastic film is a PI film;

[0042] S5. Laminating: Laminate the metal foil with an adhesive layer obtained in S3 and the plastic film obtained in S4 up and down, and simultaneously send them into a laminating wheel for lamination. After lamination, a semi-finished single-sided flexible copper clad laminate is obtained; wherein, the temperature of the laminating wheel is 70°C to 110°C and the pressure is 0.1MPa to 0.6MPa;

[0043] S6. Rewinding: Use an automatic rewinder to rewind the semi-finished single-sided flexible copper clad laminate obtained in S5, and the rewinding tension is 50N to 70N;

[0044] S7. Curing: Place the rewound semi-finished single-sided flexible copper clad laminate in a programmable temperature-controlled oven, and set its program as follows:

[0045] ① Room temperature to 60°C, heating-up time 1h, constant temperature 3h,

[0046] ② 60°C to 80°C, heating-up time 1h, constant temperature 4h,

[0047] ③ 80°C to 120°C, heating-up time 2h, constant temperature 2h,

[0048] ④ 120°C to 160°C, heating-up time 2h, constant temperature 1h,

[0049] ⑤ 160°C to room temperature, natural cooling,

[0050] After cooling, the flexible copper clad laminate is obtained.

[0051] It should be noted that the tunnel annealing oven is located between the second material feeding end and the pressing wheel, and the tunnel annealing oven is divided into four sections, with the length of each section of the oven being 2m; specifically, the temperature of the first section of the oven is 100°C to 120°C, the temperature of the second section of the oven is 160°C to 180°C, the temperature of the third section of the oven is 180°C to 200°C, and the temperature of the fourth section of the oven is 100°C to 120°C. In the present invention, after annealing, the plastic film is beneficial to further improve the dimensional stability.

[0052] Furthermore, due to the rigidity of the metal foil, its thermal shrinkage under high-temperature tension is small, the coefficient of thermal expansion is low, and the tension and surface properties of the metal foil are much better than those of the plastic film. By using the method of coating the metal foil and then laminating the plastic film, problems such as production wrinkles and appearance abnormalities caused by uneven tension of the plastic film can be significantly improved, warping can be improved, and the appearance of the product can be ensured to be flat and beautiful.

[0053] Specifically, Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 as follows:

[0054] Table 1

[0055]

[0056]

[0057] Examples 1-4 and Comparative Examples 1-2 obtained from Table 1 were subjected to performance tests on the prepared samples according to IPC TM-650 2.2.4-1998 "Dimensional Stability of Elastic Dielectric Materials", and the test results are shown in Table 2 as follows:

[0058] Table 2

[0059]

[0060] As can be seen from Table 2, the products prepared in Examples 1-4 are significantly superior to the products prepared in Comparative Examples 1-2. Specifically, the flexible copper clad laminates prepared in Examples 1-4 have a flat appearance, no warping occurs, and good dimensional stability; the flexible copper clad laminate prepared in Comparative Example 1 has a poor flatness of appearance, warping occurs, and its dimensional stability is significantly lower than that of Examples 1-4, indicating that the production process of coating copper foil and then laminating PI film can significantly improve problems such as production wrinkles and appearance abnormalities caused by uneven tension of the PI film, and to a certain extent can improve warping and increase the dimensional stability of the flexible copper clad laminate; in addition, the copper clad laminate prepared in Comparative Example 2 has serious warping and poor dimensional stability, and the only difference between Comparative Example 2 and Example 3 is the sending tension of the first sending end and the second sending end, which shows that the sending tension controlled by the preparation method in the present invention can further improve the dimensional stability of the flexible copper clad laminate, avoid warping, make the appearance flat, ensure product quality, and meet the needs of users.

[0061] The above preparation method of a flexible copper clad laminate makes the obtained flexible copper clad laminate have good dimensional stability, can improve problems such as production wrinkles and appearance abnormalities caused by uneven tension of the plastic film, improve warping at the same time, and has a simple process, is easy to operate, is beneficial to improving production efficiency, and meets production requirements.

[0062] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0063] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A preparation method of a flexible copper clad laminate, characterized in that, It includes the following steps: S1. Prepare the adhesive: First, mix rubber, epoxy resin and organic solvent, and stir at high speed to promote dissolution; then, add the filler to the mixed solution, stir and disperse at high speed, and grind the pre-solution to make the filler particle size less than or equal to 5 μm; finally, add the dissolved curing agent and set aside; S2. Feeding and coating: Place the metal foil at the first feeding end, and adopt the extrusion spraying process to input the adhesive prepared in S1 into the liquid storage and distribution cavity of the coating die head. After the homogenization effect of the transverse slit, it spreads in the form of a liquid film at the outlet lip piece onto the metal foil, and the coating thickness of the adhesive on the metal foil is 10 μm to 50 μm, where the sending tension is 30 N to 70 N and the linear speed is 10 m / min to 30 m / min; S3. Bake to surface dryness: Through a tunnel-type segmented oven, perform surface drying to obtain the metal foil with a surface-dried adhesive layer; the tunnel-type segmented oven is divided into six sections, each section of the oven is 4 m long, the temperature of the first section of the oven is 70 °C to 80 °C, the temperature of the second section of the oven is 90 °C to 100 °C, the temperature of the third section of the oven is 110 °C to 120 °C, the temperature of the fourth section of the oven is 130 °C to 140 °C, the temperature of the fifth section of the oven is 155 °C to 165 °C, and the temperature of the sixth section of the oven is 90 °C to 110 °C; S4. Annealing and sending of the plastic film: Place the plastic film at the second feeding end and send it into a tunnel-type annealing oven for preheating to obtain the preheated plastic film, where the sending tension is 20 N to 40 N and the linear speed is 10 m / min to 30 m / min; the tunnel-type annealing oven is divided into four sections, each section of the oven is 2 m long, the temperature of the first section of the oven is 100 °C to 120 °C, the temperature of the second section of the oven is 160 °C to 180 °C, the temperature of the third section of the oven is 180 °C to 200 °C, and the temperature of the fourth section of the oven is 100 °C to 120 °C; S5. Laminating: Laminate the metal foil with the adhesive layer prepared in S3 and the plastic film prepared in S4 up and down, and send them into the laminating wheel for lamination at the same time. After lamination, obtain the semi-finished single-sided flexible copper clad laminate; S6. Rewinding: Use an automatic rewinder to rewind the semi-finished single-sided flexible copper clad laminate prepared in S5; S7. Curing: Place the rewound semi-finished single-sided flexible copper clad laminate in a programmable temperature-controlled oven, and set its program as follows: ① From room temperature to 60 °C, heating time is 1 h, constant temperature is 3 h, ② From 60 °C to 80 °C, heating time is 1 h, constant temperature is 4 h, ③ From 80 °C to 120 °C, heating time is 2 h, constant temperature is 2 h, ④ From 120 °C to 160 °C, heating time is 2 h, constant temperature is 1 h, ⑤ From 160 °C to room temperature, natural cooling, After cooling, the flexible copper clad laminate is obtained.

2. The preparation method of a flexible copper clad laminate according to claim 1, wherein, The metal foil is copper foil, and its thickness is 12 μm to 70 μm.

3. The preparation method of a flexible copper clad laminate according to claim 1, characterized in that, In the step S5, the temperature of the laminating wheel is 70 °C to 110 °C, and the pressure is 0.1 MPa to 0.6 MPa.

4. The preparation method of a flexible copper clad laminate according to claim 1, wherein In the step S6, the rewinding tension is 50 N to 70 N.

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