Novel flexible circuit board manufacturing method and flexible circuit board thereof

Abstract

The invention discloses a novel flexible circuit board manufacturing method and a flexible circuit board thereof, and the novel flexible circuit board manufacturing method comprises the steps: attaching a protection film layer to the upper surface of a substrate; engraving a first groove in the protective film layer and the base material; coating a release agent on the first groove and the protective film layer to form a release agent layer; coating the workpiece to form a seed crystal layer on the surface of the release agent layer; electroplating the workpiece to form an electroplated layer on the surface of the seed crystal layer and in the first groove; etching the workpiece to remove the parts, outside the first groove, of the release agent layer, the seed crystal layer and the electroplated layer; the part, protruding out of the base material, of the release agent layer in the workpiece and the protective film layer are removed; a first thin film layer covering the seed crystal layer and the electroplated layer is formed on the upper surface of the base material through hot pressing, and the ends, located outside the base material, of the seed crystal layer and the electroplated layer are embedded into a second groove of the first thin film layer in a matched mode; and tearing off the base material on the workpiece and the residual release agent layer. The invention relates to a novel flexible circuit board manufacturing method.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to a novel flexible circuit board manufacturing method and a flexible circuit board thereof. Background Art

[0002] Flexible circuit boards are electronic circuit boards that can be bent to a certain extent, usually using polyimide (PI) or polyester (PET) as the substrate. These circuit boards are light, thin, flexible and have high space utilization, so they are widely used in various electronic products.

[0003] The existing method for making flexible circuit boards generally includes laminating, exposure, development, etching, stripping, etc. For example, application publication number CN111526666A discloses a PCB manufacturing method, which specifically discloses that it is used to make at least adjacent first metal patterns and second metal patterns; the PCB manufacturing method includes: covering the copper layer surface of the circuit board with an anti-corrosion layer; exposing the anti-corrosion layer so that the exposed part of the anti-corrosion layer not only covers the areas to be made of the first metal pattern and the second metal pattern, but also integrally covers the two adjacent ends of the first metal pattern and the second metal pattern and the outer side of the end gap; developing and removing the unexposed part of the anti-corrosion layer so that part of the copper layer is exposed; etching and removing the exposed part of the copper layer; stripping and removing the exposed part of the anti-corrosion layer.

[0004] Although the above method can also be used to manufacture circuit boards, in order to adapt to the market, it is necessary to provide a new method for manufacturing flexible circuit boards so that it can be used to meet the different needs of the market. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a new method for manufacturing a flexible circuit board and a flexible circuit board thereof, wherein the new method for manufacturing a flexible circuit board is to first complete the conductive circuit of the circuit board, and then connect it with the first film layer, etc. and tear off the substrate, thereby completing the production of the flexible circuit board. It is a new reverse production process, and it is different from the image transfer method used in the prior art, and eliminates the numerous and complicated production steps in the process.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A novel method for manufacturing a flexible circuit board, comprising:

[0008] S10, providing a substrate;

[0009] S20, attaching a protective film layer to the upper surface of the substrate;

[0010] S30, laser engraving the protective film layer and the substrate from top to bottom to form a first groove of a corresponding shape;

[0011] S40, applying a release agent on the side wall of the first groove and the surface of the protective film layer to form a release agent layer corresponding to the shape of the first groove;

[0012] S50, coating the workpiece to form a seed layer corresponding to the shape of the release agent layer on the surface of the release agent layer;

[0013] S60, electroplating the workpiece to form an electroplating layer on the surface of the seed layer, wherein the electroplating layer fills the corresponding position of the first groove;

[0014] S70, etching the workpiece, and removing the release agent layer, the seed layer, and the portion of the electroplating layer located outside the first groove;

[0015] S80, removing the portion of the release agent layer protruding from the substrate and the protective film layer in the workpiece, so that the upper surface of the substrate is exposed, and the upper end of the seed layer and the upper end of the electroplating layer are exposed from the substrate;

[0016] S90, forming a first thin film layer covering the seed layer and the electroplating layer on the upper surface of the substrate by hot pressing, and the ends of the seed layer and the electroplating layer located outside the substrate are matched and embedded in the second groove of the first thin film layer;

[0017] S100, tearing off the substrate and the remaining release agent layer on the workpiece, so that the other ends of the seed layer and the electroplating layer protrude out of the second groove;

[0018] S110, after performing anti-welding process and anti-oxidation process on the workpiece to complete surface protection, a target workpiece is obtained.

[0019] The additional structure of the above technical solution also includes the following solutions:

[0020] Furthermore, in step S90, after the lamination of the first film layer is completed, a second film layer is disposed on the end surface of the first film layer away from the substrate.

[0021] Furthermore, the first film layer is made of TPI, and the thickness of the first film layer is between 5 μm and 30 μm; the second film layer is made of PI, and the thickness of the second film layer is between 8 μm and 50 μm.

[0022] Furthermore, in step S90, after the second film layer is set, the ends of the seed layer and the electroplating layer protruding from the second groove can be embedded in a third groove of a PET substrate by hot pressing, and the seed layer and the electroplating layer are separated from the first film layer and the second film layer. The above arrangement can reduce the cost of the flexible circuit board.

[0023] Furthermore, after heating two rollers arranged in an upper and lower distribution, the strip-shaped PET substrate and the strip-shaped workpiece provided with the first film layer and the second film layer in step S90 are respectively fed between the two rollers in an upper and lower distribution manner, with the seed layer and the electroplating layer facing the PET substrate, and then under the pressure of the two rollers, the ends of the seed layer and the electroplating layer protruding from the first film layer are embedded in the third groove of the heated PET substrate, and the other ends of the seed layer and the electroplating layer are separated from the heated first film layer. The above arrangement can conveniently replace the first film layer and the second film layer with the PET substrate.

[0024] Further, in step S20, the protective film layer is made of PE, and the thickness of the protective film layer is between 8 μm and 50 μm.

[0025] Further, in step S30, the first groove engraved has a depth between 0.001 mm and 0.05 mm, and a width between 0.02 mm and 0.8 mm.

[0026] Furthermore, the coating amount of the release agent layer is between 0.1 g / ㎡ and 2 g / ㎡ and the thickness thereof is between 0.05 μm and 0.8 μm; and the release force of the release agent layer gradually decreases with the increase of the coating amount.

[0027] Further, in step S60, the seed layer and the electroplating layer are both metallic copper; the thickness of the seed layer is between 0.012 μm and 0.5 μm; the thickness of the electroplating layer outside the first groove is between 1 μm and 5 μm, and the thickness of the electroplating layer between the upper and lower ends in the first groove is between 2 μm and 3 μm.

[0028] The present invention also provides a flexible circuit board, which is manufactured using the above-mentioned novel flexible circuit board manufacturing method; the flexible circuit board includes a first film layer and a second film layer connected to each other, and an electroplating layer and a seed layer whose lower end is embedded in a first groove on the first film layer; the seed layer is coated on the top surface and both side surfaces of the electroplating layer; the first film layer is made of TPI, and the second film layer is made of PI.

[0029] The beneficial effects of the present invention are:

[0030] The present invention provides a novel method for manufacturing a flexible circuit board, wherein the present invention first completes the conductive circuit of the circuit board, then connects it with the first film layer and the second film layer, and then removes the substrate, thereby completing the manufacturing of a novel inlaid flexible circuit board, which is a new reverse manufacturing process.

[0031] In particular, the novel flexible circuit board manufacturing method of the present invention uses laser engraving to produce circuit patterns, which is different from the image transfer method used in the prior art, and eliminates the numerous and complicated production steps in the process. At the same time, the novel flexible circuit board manufacturing method of the present invention does not use the image transfer process, so it will not cause the common problems of the existing methods such as dry film glue residue, exposure, incomplete development, excessive etching, etc., that is, the production threshold is low.

[0032] In addition, it has significant advantages such as low process difficulty, shortened production time, low production cost, improved yield rate and increased production capacity, etc. It is especially suitable for the production of flexible circuit boards that do not require very high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the novel flexible circuit board manufacturing method of the present invention;

[0034] Figure 2 Schematic diagram of the method principle of S20 of the novel flexible circuit board manufacturing method of the present invention;

[0035] Figure 3 This is a schematic diagram of the method principle of S30 of the novel flexible circuit board manufacturing method of the present invention;

[0036] Figure 4 This is a schematic diagram of the method principle of S40 of the novel flexible circuit board manufacturing method of the present invention;

[0037] Figure 5 It is a schematic diagram of the method principle of S50 of the novel flexible circuit board manufacturing method of the present invention;

[0038] Figure 6 It is a schematic diagram of the principle of the method S60 of the novel flexible circuit board manufacturing method of the present invention;

[0039] Figure 7 It is a schematic diagram of the method principle of S70 of the novel flexible circuit board manufacturing method of the present invention;

[0040] Figure 8 It is a schematic diagram of the principle of the method S80 of the novel flexible circuit board manufacturing method of the present invention;

[0041] Fig. 9It is a schematic diagram of the principle of the method S90 of the novel flexible circuit board manufacturing method of the present invention;

[0042] Fig.10 This is a schematic diagram of the method principle of S100 of the novel flexible circuit board manufacturing method of the present invention;

[0043] Fig.11 It is a structural schematic diagram of the process of replacing the first film layer and the second film layer with a PET substrate in the novel flexible circuit board manufacturing method of the present invention;

[0044] Fig.12 It is a schematic diagram of the principle of a method for replacing the first film layer and the second film layer with a PET substrate in the novel flexible circuit board manufacturing method of the present invention;

[0045] Fig.13 It is a relationship diagram between the coating amount and the release force of the novel flexible circuit board manufacturing method of the present invention.

[0046] Reference numerals:

[0047] 1. Base material; 2. Protective film layer; 3. Release agent layer; 4. Seed layer; 5. Electroplating layer; 6. First film layer; 7. Second film layer; 8. PET base material; 11. First groove; 12. Second groove; 13. Third groove; 14. Roller. DETAILED DESCRIPTION

[0048] The invention is further described below in conjunction with the accompanying drawings and specific embodiments. The following description is only exemplary and does not limit the protection scope of the invention.

[0049] Embodiment 1:

[0050] like Figure 1 As shown, the present invention discloses a novel method for manufacturing a flexible circuit board, which comprises:

[0051] S10, providing a substrate 1;

[0052] like Figure 2 As shown, S20, a protective film layer 2 is attached to the upper surface of the substrate 1;

[0053] like Figure 3 As shown, S30, laser engraving the protective film layer 2 and the substrate 1 from top to bottom using an engraving machine to form a first groove 11 of a corresponding shape;

[0054] like Figure 4 As shown, S40, a release agent is applied on the side wall of the first groove 11 and the surface of the protective film layer 2 to form a release agent layer 3 corresponding to the shape of the first groove 11;

[0055] like Figure 5As shown, S50, coating the workpiece to form a seed layer 4 corresponding to the shape of the release agent layer 3 on the surface of the release agent layer 3;

[0056] like Figure 6 As shown, S60, electroplating the workpiece to form an electroplating layer 5 on the surface of the seed layer 4, and the electroplating layer 5 fills the corresponding position of the first groove 11;

[0057] like Figure 7 As shown, S70, etching the workpiece, and removing the release agent layer 3, the seed layer 4 and the portion of the electroplating layer 5 located outside the first groove 11;

[0058] like Figure 8 As shown, S80, removing the portion of the release agent layer 3 protruding from the substrate 1 and the protective film layer 2 in the workpiece, so that the upper surface of the substrate 1 is exposed, and the upper end of the seed layer 4 and the upper end of the electroplating layer 5 are exposed from the substrate 1;

[0059] like Fig. 9 As shown, S90, a first thin film layer 6 covering the seed layer 4 and the electroplating layer 5 is formed on the upper surface of the substrate 1 by hot pressing, and the ends of the seed layer 4 and the electroplating layer 5 located outside the substrate 1 are matched and embedded in the second groove 12 of the first thin film layer 6;

[0060] like Fig.10 As shown, S100, the substrate 1 and the remaining release agent layer 3 on the workpiece are torn off, so that the other ends of the seed layer 4 and the electroplating layer 5 protrude from the second groove 12;

[0061] S110, after performing solder mask process and anti-oxidation process on the workpiece to complete surface protection, the target workpiece is obtained, that is, the desired flexible circuit board is obtained.

[0062] Preferably, the substrate 1 may be made of PET, but those skilled in the art should know that the substrate 1 may also be made of other materials according to actual needs, which will not be described in detail here.

[0063] In this embodiment, the thickness of the substrate 1 is between 12.5 μm and 150 μm.

[0064] In step S90 , after the first film layer 6 is pressed, a second film layer 7 may be disposed on the end surface of the first film layer 6 away from the substrate 1 .

[0065] In this embodiment, the first film layer 6 is made of TPI, and the thickness of the first film layer 6 is between 5μm and 30μm; the second film layer 7 is made of PI, and the thickness of the second film layer 7 is between 8μm and 50μm. The thicknesses of the first film layer 6 and the second film layer 7 are obtained by researchers through actual tests, and the use effect of the first film layer 6 and the second film layer 7 at this thickness is the best.

[0066] Tripolyimide (TPI) and polyimide (PI) are ideal choices for circuit board substrate materials due to their excellent thermal stability, mechanical properties, electrical properties and chemical corrosion resistance. In addition, by connecting tripolyimide (TPI) and polyimide (PI), the advantages of the two materials can be combined to provide higher thermal stability, mechanical strength, electrical properties and chemical corrosion resistance. This method can not only realize multi-layer structure design, but also improve the overall performance of flexible circuit boards without significantly increasing costs, making them suitable for applications in various harsh environments.

[0067] Preferably, the first film layer 6 and the second film layer 7 can be connected by bonding, which can facilitate rapid and stable connection between them.

[0068] like Fig.11 and Fig.12 As shown, in order to meet the needs of different groups of people, in step S90, after the second film layer 7 is set, the end of the seed layer 4 and the electroplating layer 5 protruding from the second groove 12 can be embedded in the third groove 13 of a PET substrate 8 by hot pressing, while the seed layer 4 and the electroplating layer 5 are separated from the first film layer 6 and the second film layer 7, so that the first film layer 6 and the second film layer 7 can be replaced with the PET substrate 8. After the first film layer 6 and the second film layer 7 are made of TPI and PI materials respectively, because these materials are more expensive than PET, using PET to replace TPI and PI materials as substrates can reduce the cost of flexible circuit boards, so that it can meet the needs of some people with low budgets.

[0069] like Fig.11 and Fig.12As shown, as to how to embed the seed layer 4 and the electroplating layer 5 from the first film layer 6 and the second film layer 7 on the PET substrate 8, the specific method is: after heating two rollers 14 arranged in an upper and lower distribution, the strip-shaped PET substrate 8 and the strip-shaped workpiece provided with the first film layer 6 and the second film layer 7 in step S90 are respectively sent between the two rollers 14 in an upper and lower distribution manner (the PET substrate 8 and the workpiece can be distributed in an upper and lower manner at this time), and the seed layer 4 and the electroplating layer 5 face the PET substrate 8, and then under the pressure of the two rollers 14, the ends of the seed layer 4 and the electroplating layer 5 protruding from the first film layer 6 are embedded in the third groove 13 of the heated PET substrate 8, and the other ends of the seed layer 4 and the electroplating layer 5 are separated from the heated first film layer 6.

[0070] It should be noted that the second groove 12 and the third groove 13 mentioned above are formed by laminating the seed layer 4 and the electroplating layer 5 on the heated first film layer 6 and the PET substrate 8 respectively, and the seed layer 4 and the electroplating layer 5 are not embedded in the grooves after the grooves are pre-designed. In addition, the first film layer 6 can be liquid when pressed. The advantage of this design is that the seed layer 4 and the electroplating layer 5 can be fully matched and embedded in the first film layer 6 or the PET substrate 8, and there will be no gaps around the seed layer 4, that is, the seed layer 4 and the electroplating layer 5 are not easy to loosen, thereby improving the stability of the seed layer 4 and the electroplating layer 5 and ensuring the electrical performance.

[0071] Specifically, in order to ensure that the rollers 14 have sufficient temperature to heat the PET substrate 8 and the first film layer 6 to the required temperature, the two rollers 14 are heated to between 30° C. and 90° C. to ensure the temperature of the rollers 14 .

[0072] Preferably, in step S20, the protective film layer 2 is made of PE, and the thickness of the protective film layer 2 is between 8 μm and 50 μm. Of course, those skilled in the art should know that the thickness of the protective film layer 2 can also be set according to actual production needs.

[0073] Preferably, in step S30, the depth of the engraved first groove 11 is between 0.001 mm and 0.05 mm, and the width is between 0.02 mm and 0.8 mm. Similarly, those skilled in the art should know that the depth of the first groove 11 can also be set according to actual production needs.

[0074] Referring to the figure below, the coating amount of the release agent of the release agent layer 3 is between 0.1g / ㎡ and 2g / ㎡ and its thickness is between 0.05μm and 0.8μm. Fig.13It can be seen that the relationship between the coating amount and the release force is inversely proportional, and the release force of the release agent layer 3 gradually decreases as the coating amount increases. Therefore, the coating amount of the release agent needs to be appropriate to avoid the release force of the release agent layer 3 being too small, and the release agent layer 3 cannot be too thin to affect the use effect. The main purpose of the release agent is to make the substrate 1 easy to tear off.

[0075] In step S60, the seed layer 4 and the electroplating layer 5 are both made of metallic copper; the thickness of the seed layer 4 is between 0.012 μm and 0.5 μm; the thickness of the electroplating layer 5 outside the first groove 11 is between 1 μm and 5 μm, and the thickness between the upper and lower ends of the electroplating layer 5 inside the first groove 11 is between 2 μm and 3 μm. Those skilled in the art should know that the seed layer 4 and the electroplating layer 5 may also be made of other materials, which may be set according to actual needs.

[0076] In step S70, the etching solution used to etch the workpiece is ferric chloride, the concentration of ferric chloride is between 10% and 90%, and the temperature is between 20° C. and 80° C. Since the etching solution is prior art, it will not be described in detail here.

[0077] In summary, the main purpose of the present invention is to provide a new method for manufacturing a flexible circuit board. Among them, the present invention first completes the conductive copper circuit of the circuit board, and then connects it with the first film layer 6 and the second film layer 7, etc. and tears off the substrate 1, so as to complete the production of a new type of mosaic flexible circuit board, which is a new process for reverse production. In particular, the new method for manufacturing a flexible circuit board of the present invention uses laser engraving to make circuit graphics, which is different from the image transfer method used in the prior art, and it omits the numerous and complicated production steps in the process. At the same time, the new method for manufacturing a flexible circuit board of the present invention does not use an image transfer process, so there will be no common problems in the existing methods such as dry film glue residue, exposure, unclean development, excessive etching, etc., that is, the production threshold is low. In addition, it also has significant advantages such as low process difficulty, shortened production time, low production cost, improved yield rate and increased production capacity, etc., and is particularly suitable for making flexible circuit boards that do not require very high precision.

[0078] Embodiment 2:

[0079] like Fig.10As shown, the present invention also provides a flexible circuit board, which is made by the above-mentioned novel flexible circuit board manufacturing method; the flexible circuit board includes a first film layer 6 and a second film layer 7 connected to each other, and an electroplating layer 5 and a seed layer 4 whose lower end is embedded in a first groove 11 on the first film layer 6; the seed layer 4 is coated on the top surface and both sides of the electroplating layer 5; the first film layer 6 is made of TPI, and the second film layer 7 is made of PI. Of course, the seed layer 4 and the electroplating layer 5 are both metal copper.

[0080] Of course, as for the connection between the first film layer 6 and the second film layer 7, they are also connected by bonding.

[0081] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims and equivalent technologies of the present invention, the present invention is also intended to include these changes and modifications.

Claims

1. A novel method for manufacturing a flexible circuit board, characterized in that: include: S10, providing a substrate; S20, attaching a protective film layer to the upper surface of the substrate; S30, laser engraving the protective film layer and the substrate from top to bottom to form a first groove of a corresponding shape; S40, applying a release agent on the side wall of the first groove and the surface of the protective film layer to form a release agent layer corresponding to the shape of the first groove; S50, coating the workpiece to form a seed layer corresponding to the shape of the release agent layer on the surface of the release agent layer; S60, electroplating the workpiece to form an electroplating layer on the surface of the seed layer, wherein the electroplating layer fills the corresponding position of the first groove; S70, etching the workpiece, and removing the release agent layer, the seed layer, and the portion of the electroplating layer located outside the first groove; S80, removing the portion of the release agent layer protruding from the substrate and the protective film layer in the workpiece, so that the upper surface of the substrate is exposed, and the upper end of the seed layer and the upper end of the electroplating layer are exposed from the substrate; S90, forming a first thin film layer covering the seed layer and the electroplating layer on the upper surface of the substrate by hot pressing, and the ends of the seed layer and the electroplating layer located outside the substrate are matched and embedded in the second groove of the first thin film layer; S100, tearing off the substrate and the remaining release agent layer on the workpiece, so that the other ends of the seed layer and the electroplating layer protrude out of the second groove; S110, after performing anti-welding process and anti-oxidation process on the workpiece to complete surface protection, a target workpiece is obtained.

2. The method for manufacturing a new flexible circuit board according to claim 1, characterized in that: In step S90, after the lamination of the first film layer is completed, a second film layer is disposed on the end surface of the first film layer away from the substrate.

3. The method for manufacturing a new flexible circuit board according to claim 2, characterized in that: The first film layer is made of TPI, and the thickness of the first film layer is between 5 μm and 30 μm; the second film layer is made of PI, and the thickness of the second film layer is between 8 μm and 50 μm.

4. The method for manufacturing a new flexible circuit board according to claim 3 is characterized in that: In step S90, after completing the setting of the second film layer, the end of the seed layer and the electroplating layer protruding from the second groove can be embedded in a third groove of a PET substrate by hot pressing, and the seed layer and the electroplating layer are separated from the first film layer and the second film layer.

5. The method for manufacturing a new flexible circuit board according to claim 4, characterized in that: After heating two rollers arranged in an upper and lower distribution, the strip-shaped PET substrate and the strip-shaped workpiece provided with the first film layer and the second film layer in step S90 are respectively sent between the two rollers in an upper and lower distribution manner, and the seed layer and the electroplating layer face the PET substrate. Then, under the pressure of the two rollers, the ends of the seed layer and the electroplating layer protruding from the first film layer are embedded in the third groove of the heated PET substrate, and the other ends of the seed layer and the electroplating layer are separated from the heated first film layer.

6. The method for manufacturing a new flexible circuit board according to claim 1, characterized in that: In step S20, the protective film layer is made of PE, and the thickness of the protective film layer is between 8 μm and 50 μm.

7. The method for manufacturing a new flexible circuit board according to claim 1, characterized in that: In step S30, the first groove engraved has a depth between 0.001 mm and 0.05 mm and a width between 0.02 mm and 0.8 mm.

8. The method for manufacturing a new flexible circuit board according to claim 1, characterized in that: The release agent coating amount of the release agent layer is between 0.1 g / ㎡ and 2 g / ㎡ and the thickness thereof is between 0.05 μm and 0.8 μm; the release force of the release agent layer gradually decreases with the increase of the coating amount.

9. The method for manufacturing a new flexible circuit board according to claim 1, characterized in that: In step S60, the seed layer and the electroplating layer are both metallic copper; the thickness of the seed layer is between 0.012 μm and 0.5 μm; the thickness of the electroplating layer outside the first groove is between 1 μm and 5 μm, and the thickness of the electroplating layer between the upper and lower ends in the first groove is between 2 μm and 3 μm.

10. A flexible circuit board, characterized in that: It is manufactured by the novel flexible circuit board manufacturing method as described in any one of claims 1 to 9; the flexible circuit board includes a first film layer and a second film layer connected to each other, and an electroplating layer and a seed layer with the lower end embedded in a first groove on the first film layer; the seed layer is coated on the top surface and both side surfaces of the electroplating layer; the first film layer is made of TPI, and the second film layer is made of PI.

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