Flexible circuit board

Abstract

The utility model discloses a flexible circuit board which comprises a first insulating layer, a second insulating layer connected to the lower end of the first insulating layer and a metal layer connected to the upper end of the first insulating layer. A groove is formed in the top surface of the first insulating layer, and the lower end of the metal layer is embedded into the groove in a matched manner; the metal layer comprises a second metal layer and a first metal layer; the bottom surface of the second metal layer is connected with the bottom surface of the groove; the first metal layer covers the second metal layer in a matched manner; the bottom surface and the side surface of the first metal layer are respectively connected with the bottom surface and the side surface of the groove; the first insulating layer is made of TPI; the second insulating layer is made of PI. According to the utility model, after the first insulating layer made of TPI and the second insulating layer made of PI are connected with each other, the advantages of the two materials can be integrated to provide higher mechanical strength, the first insulating layer is not easy to break and the like, the service life of the first insulating layer is ensured, and in addition, the service life of the first insulating layer is prolonged. The structure can also provide better thermal stability, electrical performance, chemical corrosion resistance and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit boards, and particularly relates to a flexible circuit board. Background Art

[0002] A flexible circuit board is generally a highly reliable and excellent flexible printed circuit board made of a polyester film as a base material, abbreviated as a flexible board or FPC, which has the characteristics of high wiring density, light weight, and thin thickness. At present, flexible circuit boards have been widely used in various electronic products.

[0003] For a flexible circuit board, the authorized announcement number CN220528275U discloses a flexible metal-clad board and a flexible circuit board, which specifically disclose a first metal layer; an insulating layer provided on one side of the first metal layer, the insulating layer including a groove provided on the side of the insulating layer away from the first metal layer, the groove being recessed toward the side close to the first metal layer, and the depth of the groove being 20 - 1000 nm; and a second metal layer at least partially embedded in the groove.

[0004] However, although the above flexible metal-clad board discloses an insulating layer and a first metal layer and a second metal layer respectively provided on both sides of the insulating layer, and moreover, the second metal layer is at least partially embedded in a groove of the insulating layer. However, since only one insulating layer is provided, its mechanical strength is not high enough, and thus it may be relatively easy to break during use. Summary of the Utility Model

[0005] Aiming at the above problems existing in the prior art, the purpose of the utility model is to provide a flexible circuit board, which adds a second insulating layer made of PI on the first insulating layer made of TPI, so as to combine the advantages of the two materials to provide higher mechanical strength, and also make the first insulating layer not easy to break, etc., and ensure its service life.

[0006] In order to achieve the above purpose, the technical solution of the utility model is as follows:

[0007] A flexible circuit board includes a first insulating layer, a second insulating layer connected to the lower end of the first insulating layer, and a metal layer connected to the upper end of the first insulating layer; a groove is provided on the top surface of the first insulating layer, and the lower end of the metal layer is fittingly embedded in the groove; the metal layer includes a second metal layer whose bottom surface is connected to the bottom surface of the groove and a first metal layer fittingly covering the second metal layer and whose bottom surface and side surfaces are respectively connected to the bottom surface and side surfaces of the groove; the first insulating layer is made of TPI; the second insulating layer is made of PI; after the first insulating layer and the second insulating layer are interconnected, higher mechanical strength can be provided so that the first insulating layer is not easily broken.

[0008] For the additional structure of the above technical solution, the following solutions are further included:

[0009] Further, the metal layer and the first insulating layer are connected by a lamination method.

[0010] Further, the first insulating layer and the second insulating layer are connected by an adhesive method.

[0011] Further, the thickness of the first insulating layer is between 5 μm and 30 μm; the thickness of the second insulating layer is between 8 μm and 50 μm.

[0012] Further, the depth of the groove is between 0.001 mm and 0.05 mm, and the width is between 0.02 mm and 0.8 mm.

[0013] Further, the thickness of the first metal layer is between 0.012 μm and 0.5 μm; the thickness between the upper and lower end surfaces of the second metal layer is between 2 μm and 3 μm.

[0014] Further, the upper end of the first metal layer and the upper end of the second metal layer both protrude from the groove.

[0015] Further, the first metal layer and the second metal layer are made of copper, cobalt, nickel, zinc, tin or silver.

[0016] Further, the first metal layer and the second metal layer are both made of copper.

[0017] The beneficial effects of the present utility model are:

[0018] By connecting the first insulating layer made of TPI and the second insulating layer made of PI to each other, the present utility model can integrate the advantages of the two materials to provide higher mechanical strength, and also make it less likely for the first insulating layer to break, etc., ensuring its service life. In addition, this structure can also provide better thermal stability, electrical performance, chemical corrosion resistance, etc. At the same time, by embedding the first metal layer and the second metal layer in the grooves of the first insulating layer, the stability of the first metal layer and the second metal layer can be ensured, enabling it to stably form a conductive circuit. Description of the Drawings

[0019] Figure 1 is a flowchart of the method for manufacturing a flexible circuit board of the present utility model;

[0020] Figure 2 is a schematic diagram of the principle of method S20 in the method for manufacturing a flexible circuit board of the present utility model;

[0021] Figure 3 is a schematic diagram of the principle of method S30 in the method for manufacturing a flexible circuit board of the present utility model;

[0022] Figure 4 is a schematic diagram of the principle of method S40 in the method for manufacturing a flexible circuit board of the present utility model;

[0023] Figure 5 is a schematic diagram of the principle of method S50 in the method for manufacturing a flexible circuit board of the present utility model;

[0024] Figure 6 is a schematic diagram of the principle of method S60 in the method for manufacturing a flexible circuit board of the present utility model;

[0025] Figure 7 is a schematic diagram of the principle of method S70 in the method for manufacturing a flexible circuit board of the present utility model;

[0026] Figure 8 is a schematic diagram of the principle of method S80 in the method for manufacturing a flexible circuit board of the present utility model;

[0027] Figure 9 is a schematic diagram of the principle of method S90 in the method for manufacturing a flexible circuit board of the present utility model;

[0028] Figure 10 is a schematic diagram of the overall structure of the present utility model and a schematic diagram of the principle of method S100 in the method for manufacturing a flexible circuit board.

[0029] Reference Signs:

[0030] 1. Substrate; 2. Protective film layer; 3. Release agent layer; 4. First metal layer; 5. Second metal layer; 6. First insulating layer; 7. Second insulating layer; 8. Groove; 9. First groove. Detailed implementation mode

[0031] The following further elaborates on the utility model in conjunction with the attached drawings and specific embodiments. The following description is merely exemplary and does not limit the protection scope of the utility model.

[0032] Embodiment 1:

[0033] As Figure 10 shown, a flexible circuit board includes a first insulating layer 6, a second insulating layer 7 connected to the lower end of the first insulating layer 6, and a metal layer connected to the upper end of the first insulating layer 6; a groove 8 is provided on the top surface of the first insulating layer 6, and the lower end of the metal layer is fittingly embedded in the groove 8; the metal layer includes a second metal layer 5 whose bottom surface is connected to the bottom surface of the groove 8 and a first metal layer that fittingly covers the second metal layer 5 and whose bottom surface and side surface are respectively connected to the bottom surface and side surface of the groove 8; the first insulating layer 6 is made of TPI; the second insulating layer 7 is made of PI; after connecting the first insulating layer 6 and the second insulating layer 7 to each other, higher mechanical strength can be provided, so that the first insulating layer 6 is not easily broken. Of course, the second insulating layer 7 will also be very durable. Triimide (TPI) and polyimide (PI) have become ideal choices for circuit board substrate materials due to their excellent thermal stability, mechanical properties, electrical properties, and chemical corrosion resistance.

[0034] Preferably, the metal layer and the first insulating layer 6 are connected by a lamination method. This method can prevent gaps from easily occurring between the metal layer and the first insulating layer 6, so as to avoid loosening of the metal layer and affecting the use effect.

[0035] Preferably, the first insulating layer 6 and the second insulating layer 7 are connected by an adhesive method, so that the two can be quickly and stably connected.

[0036] In this embodiment, the thickness of the first insulating layer 6 is between 5 μm and 30 μm; the thickness of the second insulating layer 7 is between 8 μm and 50 μm. For the specific thicknesses of the first insulating layer 6 and the second insulating layer 7, people can set them according to actual needs.

[0037] Preferably, the depth of the groove 8 is between 0.001 mm and 0.05 mm, and the width is between 0.02 mm and 0.8 mm. For the depth and width of the groove 8, people can also set them according to actual needs.

[0038] Preferably, the thickness of the first metal layer 4 is between 0.012 μm and 0.5 μm; the thickness between the upper and lower end faces of the second metal layer 5 is between 2 μm and 3 μm. Similarly, for the thicknesses of the first metal layer 4 and the second metal layer 5, people can also set them according to actual needs.

[0039] For each of the above data, they are all the data with the best use effects obtained by the R & D personnel through actual tests.

[0040] In this embodiment, the upper ends of the first metal layer 4 and the second metal layer 5 both protrude from the groove 8. In addition, the volume of the parts of the first metal layer 4 and the second metal layer 5 protruding from the groove 8 is smaller than the volume of the parts of the first metal layer 4 and the second metal layer 5 embedded in the groove 8, so as to ensure the connection stability with the side wall of the groove 8.

[0041] Preferably, the first metal layer 4 and the second metal layer 5 are made of copper, cobalt, nickel, zinc, tin or silver. In this embodiment, both the first metal layer 4 and the second metal layer 5 are made of copper.

[0042] In summary, by connecting the first insulating layer 6 made of TPI and the second insulating layer 7 made of PI in the present utility model, the advantages of the two materials can be combined to provide higher mechanical strength, and it is also not easy for the first insulating layer 6 to break, etc., ensuring its service life. In addition, this structure can also provide better thermal stability, electrical performance and chemical corrosion resistance, etc. At the same time, by embedding the first metal layer 4 and the second metal layer 5 in the groove 8 of the first insulating layer 6, the stability of the first metal layer 4 and the second metal layer 5 can be ensured, so that it can stably form a conductive circuit.

[0043] Embodiment Two:

[0044] As Figure 1 shown, the present utility model also discloses a method for manufacturing a flexible circuit board, which is used to manufacture the above flexible circuit board, and it includes:

[0045] S10. Provide a substrate 1;

[0046] As Figure 2 shown, S20. Bond a protective film layer 2 on the upper surface of the substrate 1;

[0047] As Figure 3 shown, S30. Use a laser engraver to perform laser engraving on the protective film layer 2 and the substrate 1 from top to bottom and form a first groove 9 with a corresponding shape;

[0048] As Figure 4 shown, S40. Apply a release agent on the side wall of the first groove 9 and the surface of the protective film layer 2, and form a release agent layer 3 corresponding to the shape of the first groove 9;

[0049] As shown in Figure 5 Figure, in S50, the workpiece is coated with a film to form a first metal layer 4 on the surface of the release agent layer 3 corresponding to the shape of the release agent layer 3;

[0050] As shown in Figure 6 Figure, in S60, the workpiece is electroplated to electroplate and form a second metal layer 5 on the surface of the first metal layer 4, and the corresponding position of the first groove 9 is filled with the second metal layer 5;

[0051] As shown in Figure 7 Figure, in S70, the workpiece is etched, and the parts of the release agent layer 3, the first metal layer 4 and the second metal layer 5 located outside the first groove 9 are removed;

[0052] As shown in Figure 8 Figure, in S80, the part of the release agent layer 3 protruding from the base material 1 and the protective film layer 2 in the workpiece are removed, so that the upper surface of the base material 1 is exposed, and the upper ends of the first metal layer 4 and the second metal layer 5 are exposed above the base material 1;

[0053] As shown in Figure 9 Figure, in S90, a first insulating layer 6 covering the first metal layer 4 and the second metal layer 5 is formed by thermocompression bonding on the upper surface of the base material 1, and the ends of the first metal layer 4 and the second metal layer 5 located outside the base material 1 are fittingly embedded in the groove 8 of the first insulating layer 6; then a second insulating layer 7 is provided on the end surface of the first insulating layer 6 away from the base material 1;

[0054] As shown in Figure 10 Figure, in S100, the base material 1 and the remaining release agent layer 3 on the workpiece are torn off, so that the other ends of the first metal layer 4 and the second metal layer 5 protrude from the groove 8;

[0055] In S110, after performing the solder resist process and the antioxidant process on the workpiece to complete the surface protection, the target workpiece is obtained, that is, the desired flexible circuit board is obtained.

[0056] Preferably, the base material 1 can be made of PET, but those skilled in the art should know that the base material 1 can also be made of other materials according to actual needs, and will not be specifically described herein.

[0057] In this embodiment, the thickness of the base material 1 is between 12.5 μm and 150 μm.

[0058] 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.

[0059] Referring to the following figure, the coating amount of the release agent layer 3 is between 0.1 g / ㎡ and 2 g / ㎡, and its thickness is between 0.05 μm and 0.8 μm. Moreover, as can be seen from the following figure, 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, an appropriate amount of the release agent needs to be used to avoid too small a release force of the release agent layer 3 and not to make the release agent layer 3 too thin to affect the use effect. For the function of the release agent, its main purpose is to make the substrate 1 easy to tear off.

[0060]

[0061] In step S70, the etching solution used for etching the workpiece is ferric chloride, and 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 a prior art, it will not be specifically described here.

[0062] Therefore, the present invention provides a method for manufacturing a flexible circuit board. Among them, the present invention first completes the conductive circuit of the circuit board, and then connects it with the first insulating layer 6, the second insulating layer 7, etc. and tears off the substrate 1, so as to complete the manufacture of the new inlaid flexible circuit board, which is a new process of reverse manufacture. In particular, the method for manufacturing a flexible circuit board of the present invention uses laser engraving to manufacture circuit patterns, which is different from the image transfer method often used in the prior art, and it omits the numerous and complex manufacturing steps in the process. At the same time, the present invention does not use the image transfer process, so problems common in existing methods such as dry film glue residue, exposure light leakage, incomplete development, and over-etching will not occur, that is, the production threshold is relatively low. In addition, it also has significant advantages such as small process difficulty, shortened manufacturing time, low manufacturing cost, increased yield rate, and improved production capacity, and is particularly suitable for manufacturing flexible circuit boards with not very high precision requirements.

[0063] The present invention is not limited to the above embodiments. If various changes or deformations of the present invention do not depart from the spirit and scope of the present invention, and if these changes and deformations belong to the scope of the claims of the present invention and equivalent technical scope, then the present invention also intends to include these changes and deformations.

Claims

1. A flexible circuit board, characterized in that: The invention comprises a first insulating layer, a second insulating layer connected to the lower end of the first insulating layer, and a metal layer connected to the upper end of the first insulating layer; a groove is arranged on the top surface of the first insulating layer, and the lower end of the metal layer is matched and embedded in the groove; the metal layer comprises a second metal layer whose bottom surface is connected to the bottom surface of the groove, and a first metal layer which is matched and covered on the second metal layer and whose bottom surface and side surface are respectively connected to the bottom surface and side surface of the groove; the first insulating layer is made of TPI; the second insulating layer is made of PI; After the first insulating layer and the second insulating layer are connected to each other, higher mechanical strength can be provided, so that the first insulating layer is not prone to breakage.

2. The flexible circuit board according to claim 1, characterized in that: The metal layer and the first insulating layer are connected by pressing.

3. The flexible circuit board according to claim 1, characterized in that: The first insulating layer and the second insulating layer are connected by bonding.

4. The flexible circuit board according to claim 1, characterized in that: The thickness of the first insulating layer is between 5 μm and 30 μm; the thickness of the second insulating layer is between 8 μm and 50 μm.

5. The flexible circuit board according to claim 1, characterized in that: The depth of the groove is between 0.001 mm and 0.05 mm, and the width is between 0.02 mm and 0.8 mm.

6. The flexible circuit board according to claim 1, characterized in that: The thickness of the first metal layer is between 0.012 μm and 0.5 μm; the thickness between the upper and lower end surfaces of the second metal layer is between 2 μm and 3 μm.

7. The flexible circuit board according to claim 6, characterized in that: An upper end of the first metal layer and an upper end of the second metal layer both extend out of the groove.

8. The flexible circuit board according to claim 1, characterized in that: The first metal layer and the second metal layer are made of copper, cobalt, nickel, zinc, tin or silver.

9. The flexible circuit board according to claim 8, characterized in that: The first metal layer and the second metal layer are both made of copper.

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