Flexible circuit board Air-gap processing method

Abstract

The invention relates to the technical field of flexible circuit boards, and discloses a processing method of a flexible circuit board Ai r-gap, the circuit board comprises a first outer layer substrate, a core board and a second outer layer substrate which are sequentially arranged from top to bottom, and the processing method comprises the following steps: S1, manufacturing the core board; s2, laser processing; s3, typesetting and pressing; s4, removing glue residues; s5, mechanical drilling is conducted; s6, air guide hole laser, wherein air guide holes penetrating through the first outer-layer substrate, the core plate and the second outer-layer substrate in sequence are formed in the vertical direction; s7, plasma cleaning is conducted; s8, a second covering film is arranged, specifically, the second covering film is arranged on the plate face of the first outer-layer substrate and the plate face of the second outer-layer substrate, and the second covering film covers openings of the air guide holes; s9, black shadow and electroplating; s10, manufacturing an outer layer circuit; and S11, performing appearance laser and uncovering. The plasma cleaning method has the beneficial effects that the phenomenon that the Ai r-gap area blows and explodes the circuit board in the plasma cleaning process can be avoided, and the finished product quality of the flexible circuit board is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible circuit boards, and in particular to a processing method for an Air-gap of a flexible circuit board. Background Art

[0002] Setting an Air-gap area on the flexible circuit board can make the flexible circuit board have better bending characteristics. Generally, the larger the Air-gap area, the better without affecting the assembly. However, if the Air-gap area is too large, the vacuum is drawn during plasma cleaning, resulting in excessive pressure difference inside and outside the air-gap area, which will cause the air-gap area to bulge and explode. In the subsequent processing steps, chemicals will be hidden (for example, etching chemicals will enter the air-gap area in the subsequent processes), affecting the quality of the finished product of the flexible circuit board. Summary of the invention

[0003] The purpose of the present invention is to provide a method for processing the Air-gap of a flexible circuit board, which can avoid the explosion of the board in the Air-gap area during the plasma cleaning process and improve the quality of the finished product of the flexible circuit board.

[0004] In order to achieve the above object, the present invention provides a method for processing an Air-gap of a flexible circuit board, wherein the circuit board comprises a first outer substrate, a core substrate and a second outer substrate arranged in sequence from top to bottom, comprising the steps of:

[0005] S1. Core board production: inner layer circuits are produced on a multi-layer stacked inner layer substrate to form the core board, and hot pressing adhesive layers are provided on the bottom and top surfaces of the core board;

[0006] S2, laser processing: laser cutting the hot-pressed adhesive layer on the core board corresponding to the air-gap area of ​​the first outer substrate and the second outer substrate;

[0007] S3, layout and pressing: layout and pressing of the first outer substrate, the core substrate and the second outer substrate;

[0008] S4, removing adhesive residue: removing hot pressing adhesive residue remaining on the surface and edge of the first outer substrate, the core substrate, and the second outer substrate;

[0009] S5, mechanical drilling: opening a through hole in the vertical direction that sequentially penetrates the first outer substrate, the core substrate, and the second outer substrate;

[0010] S6, laser air guide holes: opening air guide holes that penetrate the first outer substrate, the core substrate, and the second outer substrate in sequence in the vertical direction;

[0011] S7, plasma cleaning;

[0012] S8, setting a second covering film: setting a second covering film on the surface of the first outer substrate and the second outer substrate, wherein the second covering film covers the opening of the air guide hole;

[0013] S9, Shadow and Plating;

[0014] S10, outer layer circuit manufacturing: manufacturing outer layer circuits on the first outer layer substrate and the second outer layer substrate;

[0015] S11, laser shaping and uncovering: laser-splitting the air-gap area shapes on the first outer substrate and the second outer substrate, and removing the waste materials in the air-gap area laser-splitting.

[0016] Furthermore, in the step S6: the diameter of the air guide hole is 0.1 mm-0.8 mm.

[0017] Furthermore, in step S6: the air guide hole is located in the Air-gap area or outside the Air-gap area.

[0018] Furthermore, in the step S6: the air guide hole is processed by a UV laser machine, and the aperture compensation parameter of the UV laser machine for the air guide hole is 20um-30um.

[0019] Furthermore, the step S1 specifically includes:

[0020] S100, substrate cutting;

[0021] S101, inner layer circuit production;

[0022] S102, AOI scanning circuit;

[0023] S103, browning;

[0024] S104, providing a first covering film on the bottom surface and the top surface of the core plate;

[0025] S105, punching;

[0026] S106, plasma cleaning;

[0027] S107, disposing the hot pressing adhesive layer outside the first covering film;

[0028] Furthermore, in the step S4: the hot-pressed glue stains are removed under high temperature conditions using potassium permanganate and a strong alkaline solution.

[0029] Furthermore, in the step S8: the second covering film is rectangular in size, and when covering the air guide hole, the center of the second covering film coincides with the axis of the air guide hole.

[0030] Furthermore, the step S8 specifically includes:

[0031] S81, attaching a second covering film to the surfaces of the first outer substrate and the second outer substrate, wherein the second covering film covers the openings of the air guide holes;

[0032] S82, pressing the second covering film;

[0033] S83, baking the second covering film;

[0034] Furthermore, the step S82 is specifically as follows:

[0035] The fast press is used at a temperature of 170℃-190℃ and a pressure of 110kg / cm 2 Under the conditions, the second covering film is pre-pressed for 7S-13S and pressed for 115S-125S.

[0036] Furthermore, in step S11:

[0037] The waste is removed from the air-gap area using tape.

[0038] Compared with the prior art, the processing method of the Air-gap of a flexible circuit board according to the embodiment of the present invention has the following beneficial effects: an air-conducting hole is opened in the vertical direction to sequentially penetrate the first outer substrate, the core substrate, and the second outer substrate, so as to avoid the explosion of the Air-gap region caused by vacuuming during plasma cleaning. In addition, after plasma cleaning, a covering film is used to cover the opening of the air-conducting hole to prevent the liquid medicine in the subsequent process from being stored in the Air-gap region through the air-conducting hole, thereby improving the quality of the finished product of the flexible circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural principle diagram of a flexible circuit board after layout and pressing in one embodiment of the present invention;

[0040] Figure 2 is a front view of a flexible circuit board according to an embodiment of the present invention;

[0041] Figure 3 yes Figure 2 Back view of the flexible circuit board;

[0042] Figure 4 It is a structural principle diagram of a laser air guide hole of a flexible circuit board according to an embodiment of the present invention;

[0043] Figure 5 It is a structural principle diagram of a laser air guide hole of a flexible circuit board according to an embodiment of the present invention;

[0044] Figure 6 This is a structural principle diagram of a flexible circuit board in one embodiment of the present invention in which a covering film is provided on the air guide hole;

[0045] Figure 7 It is a structural principle diagram of the outer layer circuit of a flexible circuit board according to an embodiment of the present invention;

[0046] Figure 8 This is a structural principle diagram of a flexible circuit board after laser contouring in one embodiment of the present invention;

[0047] Fig. 9 Schematic diagram comparing a flexible circuit board according to an embodiment of the present invention and a comparative example.

[0048] In the figure, L1 is the first outer substrate; L2 is the first inner substrate; L3 is the second inner substrate; L4 is the second outer substrate; 1 is the core board; 2 is the air guide hole; 3 is the first covering film; 31 is the laminating adhesive layer; 4 is the second covering film; 5 is the hot pressing adhesive layer; 6 is the copper plating layer; 7 is the through hole. DETAILED DESCRIPTION

[0049] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0050] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "inside", "outside", etc. used in the present invention to indicate the orientation or positional relationship are based on the positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred devices and elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] In the description of the present invention, it should be understood that the present invention uses the terms "first", "second", etc. to describe various information, but these information should not be limited to these terms, and these terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0052] like Figures 1 to 9 As shown, a method for processing an Air-gap of a flexible circuit board according to a preferred embodiment of the present invention, the circuit board includes a first outer substrate L1, a core substrate 1, and a second outer substrate L4 arranged in sequence from top to bottom, including the steps of:

[0053] S1, manufacturing of core board 1: manufacturing inner layer circuits on a multi-layer stacked substrate to form core board 1, and setting a hot pressing adhesive layer 5 on the bottom and top surfaces of the core board 1;

[0054] S2, laser processing: laser cutting the hot-pressed adhesive layer 5 on the core board 1 corresponding to the air-gap area of ​​the first outer substrate L1 and the second outer substrate L4;

[0055] S3, layout and pressing: layout and pressing of the first outer substrate L1, the core substrate 1, and the second outer substrate L4;

[0056] S4, removing adhesive residue: removing the hot pressing adhesive residue remaining on the board surface and edge of the first outer substrate L1, the core board 1, and the second outer substrate L4;

[0057] S5, mechanical drilling: opening a through hole 7 in the vertical direction that sequentially penetrates the first outer substrate L1, the core substrate 1, and the second outer substrate L4;

[0058] S6, laser air guide hole 2: open an air guide hole 2 in the vertical direction that passes through the first outer substrate L1, the core substrate 1, and the second outer substrate L4 in sequence;

[0059] S7, plasma cleaning; the radio frequency power supply of the plasma machine works in a specified vacuum environment, and plasma is formed in the vacuum chamber to clean the glue residue remaining on the hole wall of the through hole 7 after mechanical drilling, so as to achieve the effect of cleaning inside the hole;

[0060] S8, setting the second covering film 4: setting the second covering film 4 on the surface of the first outer substrate L1 and the second outer substrate L4, the second covering film 4 covering the opening of the air guide hole 2;

[0061] S9, black shadow and electroplating; the black shadow process uses graphite as a conductive material. Graphite is adsorbed on the hole wall that has not yet been connected after drilling on the substrate to form a conductive layer so that copper ions can be electroplated in the hole. Electroplating adopts VCP electroplating, specifically using direct current, the plate to be plated with copper as the negative electrode, and the insoluble anode as the positive electrode. When the rectifier outputs current to the positive and negative electrodes, the copper ions with rectifier charge in the solution are transferred to the copper surface of the substrate and the hole wall at the negative electrode, so that the thickness of the copper plating layer 6 meets the design requirements;

[0062] S10, outer layer circuit production: outer layer circuits are produced on the first outer layer substrate L1 and the second outer layer substrate L4; specifically, the laminating machine uses hot pressing to stick dry film on the bottom and top surfaces of the flexible circuit board. The ultraviolet rays of the exposure machine are irradiated on the dry film to transfer the circuit pattern to the board surface. After standing for 0.5-4 hours, the dry film at the unexposed position is washed away by the developer to expose the copper surface. The etching machine sprays acidic cupric chloride micro-etching solution onto the board surface, which continuously undergoes redox reactions with the copper surface to etch out the designed pattern;

[0063] S11, laser contouring, uncovering: laser separation of the Air-gap area contour on the first outer substrate L1 and the second outer substrate L4, and removal of the waste in the Air-gap area. Specifically, the CO2 laser machine uses a laser to emit a laser beam to irradiate the surface of the flexible circuit board with high energy and high density, causing it to melt and evaporate, thereby achieving the Air-gap contour cutting. During the processing, the depth of laser cutting needs to be controlled to avoid cutting the first covering film 3 corresponding to the first inner substrate L2 and the second inner substrate L3. In order to facilitate the removal of waste, in this embodiment, tape is used to adhere the waste and remove it from the Air-gap area.

[0064] In order to facilitate the description of the present invention, in this embodiment, refer to Figure 1 refer to Fig. 9 A four-layer board structure flexible circuit board is selected, wherein the first outer substrate L1 and the second outer substrate L4 are provided with a PI layer on the side facing the core board 1, and the core board 1 is a two-layer structure, specifically including a first inner substrate L2 and a second inner substrate L3, and a PI layer is provided between the first inner substrate L2 and the second inner substrate L3. In order to prevent the core board 1 from being affected by the external environment after the core board 1 is manufactured, the surfaces of the first inner substrate L2 and the second inner substrate L3 are connected with a first covering film 3 through a coating adhesive layer 31.

[0065] Wherein, step S1 specifically includes the following steps:

[0066] S100, substrate cutting;

[0067] S101, inner layer circuit production;

[0068] S102, AOI scanning circuit;

[0069] S103, browning;

[0070] S104, providing a covering film on the bottom surface and the top surface of the core plate 1;

[0071] S105, punching;

[0072] S106, plasma cleaning; the surface of the first covering film 3 can be roughened to improve the bonding strength with the hot pressing adhesive layer 5

[0073] S107 , disposing a hot-pressing adhesive layer 5 outside the first covering film 3 .

[0074] In some embodiments, in order to facilitate exhaust of the Air-gap area before plasma cleaning, the aperture size of the air guide hole 2 is 0.1mm-0.8mm. The aperture size of the air guide hole 2 can be adjusted according to actual design requirements. When the aperture is less than 0.1mm, the aperture of the air guide hole 2 is small and the exhaust effect is poor. When the aperture is greater than 0.8mm, the area occupied by the air guide hole 2 is large, which is not conducive to circuit production.

[0075] In this embodiment, see Figures 1 to 9 The air guide hole 2 is located in the Air-gap area, and can also be set outside the Air-gap area according to the circuit layout of the flexible circuit board. The air guide hole 2 can be connected to the Air-gap for exhaust, and the air guide hole 2 does not affect the circuit layout of the flexible circuit board during layout.

[0076] In some embodiments, in step S6: a UV laser machine is used to process the air guide hole 2. The UV laser machine uses an ultraviolet laser to emit a high-energy ultraviolet beam to make a hole. Since the UV laser machine is disturbed by factors such as temperature, vibration, and magnetic field, which affect the drilling accuracy, it is necessary to compensate for the aperture of the air guide hole 2 when processing the air guide hole 2. The aperture compensation parameter of the UV laser machine for the air guide hole 2 is 20um-30um. Preferably, in this embodiment, the aperture compensation parameter of the UV laser machine for the air guide hole 2 is 25um. The processing parameters of the UV laser machine are as follows:

[0077]

[0078] In step S4, in order to facilitate the removal of hot-press adhesive stains, the chemical properties of the hot-press adhesive are utilized. In this embodiment, the hot-press adhesive stains are removed by using potassium permanganate and a strong alkaline solution under high temperature conditions.

[0079] In step S8, since the air guide hole 2 is provided, in order to prevent the medicine in the subsequent process from entering the air-gap area through the air guide hole 2, a second covering film 4 is provided at the air guide hole 2. In order to facilitate cutting of the second covering film 4, the size of the second covering film 4 is rectangular. At the same time, in order to ensure the covering accuracy of the second covering film 4, the center of the second covering film 4 coincides with the axis of the air guide hole 2.

[0080] Specifically, in order to make the second covering film 4 have a good sealing effect when blocking the air guide hole 2, step S8 specifically includes: S81, attaching the second covering film 4 to the board surface of the first outer substrate L1 and the second outer substrate L4, and the second covering film 4 covers the opening of the air guide hole 2; S82, pressing the second covering film 4; S83, baking the second covering film 4. After the above process, the second covering film 4 has a good sealing effect. In this embodiment, a fast press is used to press the second covering film 4, and step S82 specifically includes:

[0081] The fast press is used at a temperature of 170℃-190℃ and a pressure of 110kg / cm 2 Under the condition of , the film is pre-pressed for 7S-13S and pressed for 115S-125S. The temperature, pressure of the quick press machine, and the pre-pressing time and pressing time of the second covering film 4 can be adjusted according to the size of the second covering film 4.

[0082] See also Fig. 9 , when other conditions remain unchanged, the flexible circuit board processed by the processing method of the present invention for processing the air-gap flexible circuit board is provided with air guide holes 2, while the comparative example does not have air guide holes 2. During the plasma cleaning process in step S7, Fig. 9 As shown in (a), the flexible circuit board provided by the present invention has no board explosion defect. Fig. 9 As shown in (b), the comparative example has a bursting defect.

[0083] In summary, the embodiment of the present invention provides a processing method for the Air-gap of a flexible circuit board, which has the beneficial effect of: opening an air guide hole 2 in the vertical direction that sequentially passes through the first outer substrate L1, the core board 1, and the second outer substrate L4, so as to avoid the explosion of the Air-gap area caused by vacuuming during plasma cleaning. In addition, after plasma cleaning, a covering film is used to cover the opening of the air guide hole 2 to prevent the liquid medicine in the subsequent process from being stored in the Air-gap area through the air guide hole 2, thereby improving the quality of the finished product of the flexible circuit board.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for processing an Air-gap of a flexible circuit board, wherein the circuit board comprises a first outer substrate, a core substrate and a second outer substrate arranged in sequence from top to bottom, characterized in that: Includes steps: S1. Core board production: inner layer circuits are produced on a multi-layer stacked inner layer substrate to form the core board, and hot pressing adhesive layers are provided on the bottom and top surfaces of the core board; S2, laser processing: laser cutting the hot-pressed adhesive layer on the core board corresponding to the air-gap area of ​​the first outer substrate and the second outer substrate; S3, layout and pressing: layout and pressing of the first outer substrate, the core substrate and the second outer substrate; S4, removing adhesive residue: removing hot pressing adhesive residue remaining on the surface and edge of the first outer substrate, the core substrate, and the second outer substrate; S5, mechanical drilling: opening a through hole in the vertical direction that sequentially penetrates the first outer substrate, the core substrate, and the second outer substrate; S6, laser air guide holes: opening air guide holes that penetrate the first outer substrate, the core substrate, and the second outer substrate in sequence in the vertical direction; S7, plasma cleaning; S8, setting a second covering film: setting a second covering film on the surface of the first outer substrate and the second outer substrate, wherein the second covering film covers the opening of the air guide hole; S9, Shadow and Plating; S10, outer layer circuit manufacturing: manufacturing outer layer circuits on the first outer layer substrate and the second outer layer substrate; S11, laser shaping and uncovering: laser-splitting the air-gap area shapes on the first outer substrate and the second outer substrate, and removing the waste materials in the air-gap area laser-splitting.

2. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S6: the diameter of the air guide hole is 0.1 mm-0.8 mm.

3. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S6: the air guide hole is located in the air-gap area or outside the air-gap area.

4. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S6: the air guide hole is processed by a UV laser machine, and the aperture compensation parameter of the UV laser machine for the air guide hole is 20um-30um.

5. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: The step S1 specifically includes: S100, substrate cutting; S101, inner layer circuit production; S102, AOI scanning circuit; S103, browning; S104, providing a first covering film on the bottom surface and the top surface of the core plate; S105, punching; S106, plasma cleaning; S107, disposing the heat-pressed adhesive layer outside the first covering film.

6. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S4: the hot pressing glue stains are removed under high temperature conditions using potassium permanganate and strong alkaline solution.

7. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S8 : the second covering film is rectangular in size, and when covering the air guide hole, the center of the second covering film coincides with the axis of the air guide hole.

8. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: The step S8 specifically includes: S81, attaching a second covering film to the surfaces of the first outer substrate and the second outer substrate, wherein the second covering film covers the openings of the air guide holes; S82, pressing the second covering film; S83, baking the second covering film.

9. The method for processing the air-gap of a flexible circuit board as claimed in claim 8, characterized in that: The step S82 is specifically as follows: The fast press is used at a temperature of 170℃-190℃ and a pressure of 110kg / cm 2 Under the conditions, the second covering film is pre-pressed for 7S-13S and pressed for 115S-125S.

10. The method for processing the air-gap of a flexible circuit board according to claim 1, characterized in that: In the step S11: The waste is removed from the air-gap area using tape.

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