Flexible circuit board based on multilayer board

Abstract

The flexible circuit board comprises a first lamination layer, a bonding layer and a second lamination layer which are stacked in sequence, the first lamination layer comprises a first aluminum layer and a second aluminum layer which are stacked in sequence, and a first copper layer is plated on the face, away from the second aluminum layer, of the first aluminum layer; the second lamination layer comprises a third aluminum layer and a fourth aluminum layer which are sequentially laminated, and a second copper layer is plated on one surface, far away from the third aluminum layer, of the fourth aluminum layer; the bonding layers are arranged between the first part of the first lamination layer and the first part of the second lamination layer and between the third part of the first lamination layer and the third part of the second lamination layer so that the first lamination layer and the second lamination layer can be fixedly connected, and therefore the purpose that an aluminum material serves as a main base material of the flexible circuit board is achieved. The production cost of the flexible circuit board based on the multilayer board is effectively reduced, the heat dissipation uniformity of the flexible circuit board is improved, and the light weight of the flexible circuit board is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible circuit board, in particular to a flexible circuit board based on multi-layer board. BACKGROUND

[0002] The existing multi-layer flexible circuit board is generally provided with a multi-layer board, and the material of the multi-layer board is generally pure copper material. However, the multi-layer flexible circuit board with such structure has high material cost, and is prone to local heat accumulation due to the fast heat conduction of copper, and cannot reduce the overall weight of the circuit board due to the large weight of copper. SUMMARY

[0003] The present application aims to provide a flexible circuit board based on multi-layer board, which has low production cost, good heat dissipation uniformity and light weight structure.

[0004] In order to achieve the above-mentioned purpose, the present application discloses a flexible circuit board based on multi-layer board, which comprises: a first stack, an adhesive layer and a second stack arranged in sequence; The first stack and the second stack each comprise a first part, a second part and a third part arranged along the transverse direction; The first stack comprises a first aluminum layer and a second aluminum layer arranged in sequence, and the first aluminum layer is plated with a first copper layer on the side away from the second aluminum layer; the second stack comprises a third aluminum layer and a fourth aluminum layer arranged in sequence, and the fourth aluminum layer is plated with a second copper layer on the side away from the third aluminum layer; The adhesive layer is arranged between the first parts of the first stack and the second stack, and is arranged between the third parts of the first stack and the second stack.

[0005] Preferably, the flexible circuit board based on multi-layer board is provided with at least one conductive via hole corresponding to the third parts of the first stack and the second stack, and the side wall of the conductive via hole is used to electrically connect the first copper layer and the second copper layer.

[0006] Preferably, the thickness of the second aluminum layer is greater than or equal to 31um; the thickness of the third aluminum layer is greater than or equal to 42um; the total thickness of the first aluminum layer and the first copper layer is greater than or equal to 45um; and the total thickness of the fourth aluminum layer and the second copper layer is greater than or equal to 45um.

[0007] Preferably, the first stack further includes a first protective film disposed between the first aluminum layer and the second aluminum layer, and both sides of the first protective film are fixedly bonded to the first aluminum layer and the second aluminum layer by a first adhesive; the second stack further includes a second protective film disposed between the third aluminum layer and the fourth aluminum layer, and both sides of the second protective film are fixedly bonded to the third aluminum layer and the fourth aluminum layer by a first adhesive.

[0008] Preferably, the first protective film and the second protective film are made of polyimide, the thickness of the first protective film is in the range of 23um to 27um, and the thickness of the second protective film is in the range of 10.5um to 14.5um; the first adhesive is made of pure rubber, and the thickness of the first adhesive is in the range of 15um to 25um.

[0009] Preferably, the adhesive layer includes an adhesive sheet, on both sides of which a third protective film and a fourth protective film are fixedly attached, spanning a first portion, a second portion, and a third portion of the first stack and the second stack, respectively. The third protective film is fixedly bonded to the second aluminum layer by a second adhesive, and the fourth protective film is fixedly bonded to the third aluminum layer by a second adhesive.

[0010] Preferably, the adhesive sheet is made of epoxy resin and has a thickness ranging from 25µm to 41µm; the third and fourth protective films are made of polyimide and have a thickness ranging from 10.5µm to 14.5µm; and the second adhesive is made of epoxy resin and has a thickness ranging from 27µm to 39µm.

[0011] Preferably, a fifth protective film is provided on the side of the first copper layer away from the first aluminum layer, corresponding to the first portion and the second portion of the first stack, and the fifth protective film is fixedly bonded to the first copper layer by a third adhesive; a sixth protective film is provided on the side of the second copper layer away from the fourth aluminum layer, corresponding to the first portion, the second portion and the third portion of the second stack, and the sixth protective film is fixedly bonded to the second copper layer by a third adhesive.

[0012] Preferably, the fifth and sixth protective films are made of polyimide, and the thickness of the fifth and sixth protective films ranges from 10.5 μm to 14.5 μm; the third adhesive is made of pure rubber, and the thickness of the third adhesive ranges from 39 μm to 55 μm.

[0013] Preferably, the first and third portions of the first stack are provided with an ink solder resist layer on the side away from the second stack, and / or the third portion of the second stack is provided with a reinforcing layer on the side away from the first stack.

[0014] Compared with the prior art, the present invention comprises a first stacked layer, an adhesive layer, and a second stacked layer stacked sequentially. The first stacked layer includes a first aluminum layer and a second aluminum layer stacked sequentially, with a first copper layer plated on the side of the first aluminum layer away from the second aluminum layer. The second stacked layer includes a third aluminum layer and a fourth aluminum layer stacked sequentially, with a second copper layer plated on the side of the fourth aluminum layer away from the third aluminum layer. The adhesive layer is disposed between the first portion of the first stacked layer and the second stacked layer and between the third portion of the first stacked layer and the second stacked layer to achieve a fixed connection between the first stacked layer and the second stacked layer. This enables the use of aluminum as the main substrate of the flexible circuit board, effectively reducing the production cost of the flexible circuit board based on multilayer boards, improving the heat dissipation uniformity of the flexible circuit board, and achieving the lightweighting of the flexible circuit board. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram of a flexible circuit board based on a multilayer board according to an embodiment of the present invention. Detailed Implementation

[0016] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0017] Please see Figure 1 This invention discloses a flexible circuit board based on a multilayer board, comprising: The first layer 1, the adhesive layer 2, and the second layer 3 are stacked sequentially. Both the first stack 1 and the second stack 2 include a first part 101, a second part 102 and a third part 103 arranged in a transverse direction; The first stack 1 includes a first aluminum layer 11 and a second aluminum layer 12 stacked in sequence, and a first copper layer 13 is plated on the side of the first aluminum layer 11 away from the second aluminum layer 12; the second stack 3 includes a third aluminum layer 31 and a fourth aluminum layer 32 stacked in sequence, and a second copper layer 33 is plated on the side of the fourth aluminum layer 32 away from the third aluminum layer 31. The adhesive layer 2 is stacked between the first portion 101 of the first layer 1 and the second layer 2, and is stacked between the third portion 103 of the first layer 1 and the second layer 2.

[0018] Compared with the prior art, the present invention comprises a first stacked layer 1, an adhesive layer 2, and a second stacked layer 3 stacked sequentially. The first stacked layer 1 includes a first aluminum layer 11 and a second aluminum layer 12 stacked sequentially. The side of the first aluminum layer 11 away from the second aluminum layer 12 is plated with a first copper layer 13. The second stacked layer 3 includes a third aluminum layer 31 and a fourth aluminum layer 32 stacked sequentially. The side of the fourth aluminum layer 32 away from the third aluminum layer 31 is plated with a second copper layer 33. The adhesive layer 2 is disposed between the first portion 101 of the first stacked layer 1 and the second stacked layer 3 and between the third portion 103 of the first stacked layer 1 and the second stacked layer 3 to achieve a fixed connection between the first stacked layer 1 and the second stacked layer 3. This enables the use of aluminum as the main substrate of the flexible circuit board, effectively reducing the production cost of the flexible circuit board based on multilayer boards, improving the heat dissipation uniformity of the flexible circuit board, and achieving the lightweighting of the flexible circuit board.

[0019] See Figure 1 The flexible circuit board based on the multilayer board has at least one conductive via 4 in the third part 103 corresponding to the first stack 1 and the second stack 3. The sidewall of the conductive via 4 is used to electrically connect the first copper layer 13 and the second copper layer 33.

[0020] Specifically, in this embodiment, the first copper layer 13 and the second copper layer 33 are respectively printed with conductive lines, and the conductive via 4 is a plated through hole (PTH). The conductive lines of the first copper layer 13 and the conductive lines of the second copper layer 33 are electrically connected through the conductive via 4, but not limited to this.

[0021] See Figure 1 The thickness of the second aluminum layer 12 is greater than or equal to 31 μm; the thickness of the third aluminum layer 31 is greater than or equal to 42 μm; the total thickness of the first aluminum layer 11 and the first copper layer 13 is greater than or equal to 45 μm; and the total thickness of the fourth aluminum layer 32 and the second copper layer 33 is greater than or equal to 45 μm.

[0022] Specifically, in this embodiment, the thickness of the second aluminum layer 12 and the third aluminum layer 31 is 31um, which is beneficial to maintain the rigidity of the flexible circuit board while keeping it lightweight, but is not a limitation.

[0023] Specifically, in this embodiment, the thickness of the first aluminum layer 11 and the fourth aluminum layer 32 is 31 μm, and the thickness of the first copper layer 13 and the second copper layer 33 is 18 μm. This is beneficial for maintaining the rigidity of the flexible circuit board while keeping it lightweight, but it is not a limitation.

[0024] See Figure 1The first layer 1 further includes a first protective film 14 disposed between the first aluminum layer 11 and the second aluminum layer 12. Both sides of the first protective film 14 are fixedly bonded to the first aluminum layer 11 and the second aluminum layer 12 by a first adhesive 51. The second layer 3 further includes a second protective film 34 disposed between the third aluminum layer 31 and the fourth aluminum layer 32. Both sides of the second protective film 34 are fixedly bonded to the third aluminum layer 31 and the fourth aluminum layer 32 by a first adhesive 51, which is beneficial to the stable connection between the first aluminum layer 11 and the second aluminum layer 12 and between the third aluminum layer 31 and the fourth aluminum layer 32.

[0025] Furthermore, the first protective film 14 and the second protective film 34 are made of polyimide, the thickness of the first protective film 14 is in the range of 23um to 27um, and the thickness of the second protective film 34 is in the range of 10.5um to 14.5um; the first adhesive 51 is made of pure rubber, and the thickness of the first adhesive 51 is in the range of 15um to 25um.

[0026] Specifically, in this embodiment, the thickness of the first protective film 14 is 25 μm, the thickness of the second protective film 34 is 12.5 μm, and the thickness of the first adhesive 51 is 20 μm, but this is not a limitation.

[0027] See Figure 1 The adhesive layer 2 includes an adhesive sheet 21. A third protective film 22 and a fourth protective film 23, which span the first part 101, the second part 102 and the third part 103 of the first stack 1 and the second stack 3 respectively, are fixedly attached to both sides of the adhesive sheet 21. The third protective film 22 is fixedly bonded to the second aluminum layer 12 by the second adhesive 52, and the fourth protective film 23 is fixedly bonded to the third aluminum layer 31 by the second adhesive 52. This helps to maintain the insulation between the first stack 1 and the second stack 3. Furthermore, the adhesive sheet 21 is only correspondingly provided to the first part 101 and the third part 103 of the first stack 1 and the second stack 3, which is beneficial for the flexible circuit board to be bent along the opposite sides laterally.

[0028] Furthermore, the adhesive sheet 21 is made of epoxy pure rubber, and the thickness of the adhesive sheet 21 ranges from 25um to 41um; the third protective film 22 and the fourth protective film 23 are made of polyimide, and the thickness of the third protective film 22 and the fourth protective film 23 ranges from 10.5um to 14.5um; the second adhesive 52 is made of pure rubber, and the thickness of the second adhesive 52 ranges from 27um to 39um, which is beneficial to maintaining a stable bond between the first laminate 1 and the second laminate 3.

[0029] Specifically, in this embodiment, the thickness of the adhesive sheet 21 is 33 μm, the thickness of the third protective film 22 and the fourth protective film 23 is 12.5 μm, and the thickness of the second adhesive 52 is 33 μm, but this is not a limitation.

[0030] See Figure 1 A fifth protective film 14 is provided on the side of the first copper layer 13 away from the first aluminum layer 11, corresponding to the first part 101 and the second part 102 of the first stack 1. The fifth protective film 14 is fixedly bonded to the first copper layer 13 by a third adhesive 53. A sixth protective film 34 is provided on the side of the second copper layer 33 away from the fourth aluminum layer 32, corresponding to the first part 101, the second part 102 and the third part 103 of the second stack 3. The sixth protective film 34 is fixedly bonded to the second copper layer 33 by a third adhesive 53, which is beneficial for protecting the first copper layer 13 and the second copper layer 33.

[0031] Furthermore, the fifth protective film 14 and the sixth protective film 34 are made of polyimide, and their thickness ranges from 10.5 μm to 14.5 μm; the third adhesive 53 is made of pure glue, and its thickness ranges from 39 μm to 55 μm, which helps to ensure that the fifth protective film 14 and the sixth protective film 34 are stably bonded to the first copper layer 13 and the second copper layer 33, respectively.

[0032] Specifically, in this embodiment, the thickness of the third protective film 22 and the fourth protective film 23 is 12.5 μm, and the thickness of the third adhesive 53 is 47 μm, but this is not a limitation.

[0033] See Figure 1 An ink resist layer 6 is stacked on the side of the first portion 101 and the third portion 103 of the first stack 1 away from the second stack 3, and / or a reinforcing layer 7 is stacked on the side of the third portion 103 of the second stack 3 away from the first stack 1.

[0034] Specifically, in this embodiment, the thickness of the ink solder resist layer 6 is 25 μm, but it is not limited to this. In some embodiments, the thickness of the ink solder resist layer 6 ranges from 10 μm to 40 μm.

[0035] Specifically, in this embodiment, the reinforcing layer 7 includes a third adhesive 71 and a steel sheet 72 bonded to the third portion 103 of the second stack 3 by the third adhesive 71. The thickness of the third adhesive 71 is 28 μm and the thickness of the steel sheet 72 is 150 μm, but it is not limited to this. In some embodiments, the thickness of the third adhesive 71 ranges from 18 μm to 38 μm and the thickness of the steel sheet 72 ranges from 135 μm to 165 μm.

[0036] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A flexible circuit board based on a multilayer board, characterized in that, include: The first layer, the adhesive layer, and the second layer are stacked sequentially. Both the first stack and the second stack include a first portion, a second portion, and a third portion arranged laterally; The first stack includes a first aluminum layer and a second aluminum layer stacked sequentially, and a first copper layer is plated on the side of the first aluminum layer away from the second aluminum layer; the second stack includes a third aluminum layer and a fourth aluminum layer stacked sequentially, and a second copper layer is plated on the side of the fourth aluminum layer away from the third aluminum layer. The adhesive layer is stacked between the first portion of the first stack and the second stack, and is also stacked between the third portion of the first stack and the second stack.

2. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, The flexible circuit board based on the multilayer board has at least one conductive via in the third part corresponding to the first stack and the second stack, and the sidewall of the conductive via is used to electrically connect the first copper layer and the second copper layer.

3. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, The thickness of the second aluminum layer is greater than or equal to 31 μm; The thickness of the third aluminum layer is greater than or equal to 42 μm; The total thickness of the first aluminum layer and the first copper layer is greater than or equal to 45 μm; The total thickness of the fourth aluminum layer and the second copper layer is greater than or equal to 45 μm.

4. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, The first layer further includes a first protective film disposed between the first aluminum layer and the second aluminum layer, and both sides of the first protective film are fixedly bonded to the first aluminum layer and the second aluminum layer by a first adhesive. The second layer further includes a second protective film disposed between the third aluminum layer and the fourth aluminum layer, and both sides of the second protective film are fixedly bonded to the third aluminum layer and the fourth aluminum layer by a first adhesive.

5. The flexible circuit board based on a multilayer board according to claim 4, characterized in that, The first protective film and the second protective film are made of polyimide. The thickness of the first protective film ranges from 23 μm to 27 μm, and the thickness of the second protective film ranges from 10.5 μm to 14.5 μm. The first adhesive is made of pure rubber, and its thickness ranges from 15µm to 25µm.

6. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, The adhesive layer includes an adhesive sheet, on which a third protective film and a fourth protective film are fixedly attached to the two sides of the adhesive sheet, respectively, spanning a first portion, a second portion, and a third portion of the first stack and the second stack. The third protective film is fixedly bonded to the second aluminum layer by a second adhesive, and the fourth protective film is fixedly bonded to the third aluminum layer by a second adhesive.

7. The flexible circuit board based on a multilayer board according to claim 6, characterized in that, The adhesive sheet is made of epoxy pure rubber, and the thickness of the adhesive sheet ranges from 25um to 41um. The third and fourth protective films are made of polyimide, and their thickness ranges from 10.5 μm to 14.5 μm. The second adhesive is made of pure rubber, and its thickness ranges from 27µm to 39µm.

8. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, A fifth protective film is provided on the side of the first copper layer away from the first aluminum layer, corresponding to the first part and the second part of the first stack. The fifth protective film is fixedly bonded to the first copper layer by a third adhesive. A sixth protective film is provided on the side of the second copper layer away from the fourth aluminum layer, corresponding to the first, second and third portions of the second stack. The sixth protective film is fixedly bonded to the second copper layer by a third adhesive.

9. The flexible circuit board based on a multilayer board according to claim 8, characterized in that, The fifth and sixth protective films are made of polyimide, and their thickness ranges from 10.5 μm to 14.5 μm; the third adhesive is made of pure rubber, and its thickness ranges from 39 μm to 55 μm.

10. The flexible circuit board based on a multilayer board according to claim 1, characterized in that, The first and third portions of the first stack have an ink resist layer stacked on the side away from the second stack; and / or, A reinforcing layer is stacked on the side of the third portion of the second layer away from the first layer.

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