Rigid-flex board backing plate and manufacturing method thereof

Abstract

The invention provides a rigid-flex board base plate and a manufacturing method thereof.The rigid-flex board base plate manufactured through the method is used for improving drilling burrs caused by the height difference of the board surfaces of rigid-flex boards composed of flexible circuit boards and rigid circuit boards, and the method comprises the steps that information of a concave area of the rigid-flex boards is obtained; a printing area is determined on the base plate base material based on the information of the sunken areas, the printing area on the base plate base material is coated with a filling material, the filling material is cured, the rigid-flex board base plate is obtained after the filling material is cured, and the information of the sunken areas comprises the number information, the position information and the size information of the sunken areas on the rigid-flex board; the area of each printing area is not smaller than the area of the drilling area and not larger than the area of the corresponding concave area. According to the scheme, use is easy and convenient, cost is low, burrs generated in the drilling process can be effectively restrained, new processes and equipment do not need to be added, production efficiency is improved, and damage to the circuit board cannot be caused.

Description

Technical Field

[0001] The present invention belongs to the technical field of printed circuits, and particularly relates to a backing plate for a rigid-flexible printed circuit board and a manufacturing method thereof. Background Art

[0002] A backing plate is placed under a plate to be processed during mechanical drilling of a printed circuit board (referred to as PCB for short) to improve the drilling effect. The main functions of a PCB backing plate are to suppress burrs at the drilling exit, improve hole position accuracy, reduce the temperature of the drill bit, and protect the drilling machine table.

[0003] During the PCB drilling process, rigid-flexible printed circuit boards are often encountered. A rigid-flexible printed circuit board is obtained by combining a flexible printed circuit board and a rigid printed circuit board through processes such as lamination. Windowing processing will cause height differences on the board surface. Therefore, a rigid-flexible printed circuit board has a sunken area, and the sunken area will cause a gap between a conventional backing plate and the rigid-flexible printed circuit board. When drilling the sunken area, the backing plate cannot play a normal role in suppressing burrs.

[0004] Although related technologies have proposed to suppress drilling burrs by coating a layer on the PCB surface, this method requires adding new processes such as coating, curing, and film stripping and related equipment. The operation is cumbersome, time-consuming and laborious, the cost is high, and it is easy to generate a large amount of waste water and waste residues.

[0005] In addition, if burrs are removed by grinding, the copper layer will be damaged, resulting in poor product quality of the rigid-flexible printed circuit board after drilling. Although coating a layer on the surface of the rigid-flexible printed circuit board can suppress drilling burrs, it needs to be soaked in a specific potion for film stripping after drilling, and such a specific potion will damage the PI, affect copper plating, and the operation is cumbersome, time-consuming and laborious, and it is easy to generate a large amount of waste water and waste residues. Summary of the Invention

[0006] In order to overcome the defects of the above-mentioned prior art, the present invention proposes a manufacturing method of a backing plate for a rigid-flexible printed circuit board. The backing plate for a rigid-flexible printed circuit board obtained by the method is used to improve the drilling burrs caused by the height difference on the board surface of a rigid-flexible printed circuit board composed of a flexible printed circuit board and a rigid printed circuit board. The method includes:

[0007] Obtaining the sunken area information of the rigid-flexible printed circuit board; the sunken area information includes the quantity information of the sunken areas on the rigid-flexible printed circuit board, the position information and size information of each sunken area;

[0008] Determining a printing area on the backing plate substrate based on the sunken area information; the area of each printing area is not less than the drilling area and not greater than the area of the corresponding sunken area;

[0009] Coat the printing area on the backing substrate with a filling material, and cure the filling material to obtain the flexible-rigid PCB backing plate after the filling material is cured.

[0010] Specifically, the obtaining of the concave area information of the flexible-rigid PCB includes:

[0011] Obtain information on the flexible printed circuit board and the rigid printed circuit board that make up the flexible-rigid PCB;

[0012] Based on the information of the flexible printed circuit board and the rigid printed circuit board, obtain the concave area information of the flexible-rigid PCB.

[0013] Further, the determining of the printing area on the backing substrate based on the concave area information includes:

[0014] Make a film pattern based on the concave area information;

[0015] After the film pattern is attached to the screen frame, expose the screen frame to obtain a graphic screen plate;

[0016] Determine the printing area on the backing substrate through the graphic screen plate.

[0017] Preferably, the method further includes:

[0018] Open at least two positioning holes on the backing substrate to correspond to the positioning holes opened at the corresponding positions on the flexible-rigid PCB, and correspondingly set positioning circles at the positions of the graphic screen plate corresponding to the positioning holes on the backing substrate; the diameter of each positioning hole is 2.0 - 3.5 mm, the diameter of the positioning circle is larger than the corresponding positioning hole, and the diameter difference between the positioning circle and the corresponding positioning hole is not more than 1.0 mm.

[0019] Preferably, the thickness of the filling material coated on the printing area of the backing substrate is 90% - 130% of the depth of the concave area corresponding to the printing area.

[0020] Preferably, the filling material includes, but is not limited to, a mixture of one or more resins such as epoxy and its modified resins, polyurethane and its modified resins, acrylate and its modified resins, unsaturated polyester and its modified resins.

[0021] Specifically, the curing of the filling material includes:

[0022] Determine the type of the filling material, and select one or more of baking curing, light curing, and room temperature curing based on the type of the filling material to cure and form the filling material, so that the cured filling material meets the conditions of a hardness of not less than 5B, a fineness of not more than 45 um, and a viscosity of not less than 2000 mPa·s.

[0023] Optionally, the backing plate substrate includes aluminum sheet, PET, cold stamping plate, epoxy board, PP, PVC, acrylic board or iron sheet.

[0024] Preferably, the backing plate substrate includes PET, cold stamping plate or aluminum sheet with a thickness of 0.01 - 3 mm.

[0025] The present invention also provides a rigid - flexible printed circuit board backing plate, which is prepared according to the method described above.

[0026] The present invention has at least the following beneficial effects:

[0027] The solution proposed by the present invention is applicable to drilling of rigid - flexible printed circuit boards with regular recessed areas. By utilizing the filling and high - hardness characteristics of the filling - type backing plate, the rigid - flexible printed circuit board backing plate can fill the recessed areas of the rigid - flexible printed circuit board, enabling the backing plate to closely fit with the rigid - flexible printed circuit board, and achieving the purpose of suppressing burrs generated in the drilling process of the rigid - flexible printed circuit board in a relatively simple manner and at a low cost;

[0028] Furthermore, the graphic screen plate made through the film pattern in this solution can accurately determine the printing area, thereby better ensuring the accuracy and consistency of the printing area. At the same time, this solution realizes the precise positioning of the backing plate and the rigid - flexible printed circuit board through the design of positioning holes, and precisely controls the numerical values to reduce the gap between the rigid - flexible printed circuit board backing plate and the rigid - flexible printed circuit board, ensuring that the rigid - flexible printed circuit board backing plate plays a role in suppressing burrs of the rigid - flexible printed circuit board. This solution also provides various choices of filling materials and curing methods, which can meet different needs and requirements, and thus adapt to a variety of different application scenarios, having good flexibility.

[0029] Therefore, the present invention provides a rigid - flexible printed circuit board backing plate and its manufacturing method. This solution is easy to use and has a low cost, and can effectively suppress burrs generated during the drilling process. Compared with the method of suppressing burrs through coating in the prior art, this solution can increase production efficiency without adding new processes and equipment, and will not cause damage to the printed circuit board itself. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic diagram of the overall process of the manufacturing method of the rigid - flexible printed circuit board backing plate provided for Embodiment 1;

[0032] Figure 2Schematic diagram of a rigid-flex printed circuit board and a backing plate of a rigid-flex printed circuit board obtained by the method of Example 1;

[0033] Figure 3 Schematic flowchart for obtaining information on the concave area of a rigid-flex printed circuit board;

[0034] Figure 4 Schematic flowchart for manufacturing a pattern screen;

[0035] Figure 5 Example diagram of a rigid-flex printed circuit board;

[0036] Figure 6 Example diagram of a pattern screen. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Hereinafter, various embodiments of the present invention will be described more comprehensively. The present invention can have various embodiments and adjustments and changes can be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present invention to the specific embodiments disclosed herein, but the present invention should be understood to cover all adjustments, equivalents and / or alternative solutions falling within the spirit and scope of the various embodiments of the present invention.

[0039] Hereinafter, the term "comprising" or "may comprise" that can be used in various embodiments of the present invention indicates the presence of the disclosed functions, operations or elements, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "comprising", "having" and their cognates are only intended to represent a specific feature, number, step, operation, element, component or combination of the foregoing items, and should not be construed as precluding the existence or addition of the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0040] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the recited words. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0041] In various embodiments of the present invention, expressions (such as "first", "second", etc.) used may modify various components in the various embodiments, but do not limit the corresponding components. For example, the above expressions do not limit the order and / or importance of the components. The above expressions are only for the purpose of distinguishing one component from other components. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

[0042] It should be noted that: in the present invention, unless otherwise clearly specified and defined, terms such as "installed", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium; it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0043] In the present invention, those of ordinary skill in the art need to understand that the terms indicating the orientation or positional relationship in the text are based on the orientation or 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 device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0044] The terms used in the various embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present invention. As used herein, the singular form is also intended to include the plural form unless the context clearly indicates otherwise. Unless otherwise limited, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as those defined in a general use dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present invention.

[0045] Embodiment 1

[0046] See Figure 1 、 Figure 2, this embodiment proposes a method for manufacturing a backing plate for a flexible-rigid printed circuit board. The backing plate for the flexible-rigid printed circuit board obtained by the method proposed in this embodiment is used to cooperate with the drilling process of a flexible-rigid printed circuit board composed of a flexible printed circuit board and a rigid printed circuit board, and is specifically used to improve the drilling burrs caused by the height difference on the surface of the flexible-rigid printed circuit board composed of a flexible printed circuit board and a rigid printed circuit board. The flexible-rigid printed circuit board is specifically obtained by combining a flexible printed circuit board and a rigid printed circuit board through related processes such as lamination. The method includes:

[0047] S100: Obtain the information of the sunken area of the flexible-rigid printed circuit board.

[0048] Specifically, the information of the sunken area includes the quantity information of the sunken areas on the flexible-rigid printed circuit board, the position information, and the dimension information of each sunken area. In this embodiment, the dimension information of the sunken area includes the shape information, the size information, and the depth information of the sunken area.

[0049] S200: Determine the printing area on the backing plate substrate based on the information of the sunken area.

[0050] Specifically, the backing plate substrate may include, but is not limited to, aluminum sheets, PET, cold punching plates, epoxy boards, PP, PVC, acrylic plates, and iron sheets. Preferably, PET, cold punching plates, or aluminum sheets with a thickness of 0.01 - 3 mm can be selected as the backing plate substrate, which can effectively prevent the backing plate from deforming while manufacturing the backing plate at a relatively low cost, is beneficial to drilling alignment, and will not have a negative impact on the qualified rate of drilling burrs.

[0051] S300: Coat the filling material on the printing area of the backing plate substrate and cure the filling material to obtain the backing plate for the flexible-rigid printed circuit board after the filling material is cured.

[0052] Preferably, the thickness of the filling material coated on the printing area of the backing plate substrate is 90% - 130% of the depth of the corresponding sunken area of the printing area, and the thickness of the overflow part of the filling material at the edge of the printing area should not be greater than 20% of the depth of the corresponding sunken area of the printing area, so as to ensure that the cost of the required filling material is not too high while being able to minimize the gap between the backing plate for the flexible-rigid printed circuit board and the flexible-rigid printed circuit board as much as possible, and ensure that the effect of suppressing drilling burrs can be achieved.

[0053] Thus, before applying the drilling process to the flexible-rigid printed circuit board, the filling material in the printing area of the backing plate for the flexible-rigid printed circuit board obtained by the method of this embodiment can be combined with the sunken area of the flexible-rigid printed circuit board, so that the backing plate for the flexible-rigid printed circuit board is closely attached to the flexible-rigid printed circuit board, and then the effect of suppressing drilling burrs can be achieved when applying the drilling process.

[0054] It should be noted that to prevent the filling material from being unable to suppress the burrs at the edge holes, the area of each printing area shall not be less than the area of the drilling area; in order to completely fit the raised part of the backing plate of the rigid-flex printed circuit board into the recessed area of the rigid-flex printed circuit board to achieve the effect of suppressing burrs and prevent gaps between the backing plate of the rigid-flex printed circuit board and the rigid-flex printed circuit board, the area of each printing area shall also not be greater than the area of the corresponding recessed area.

[0055] The filling material in this embodiment can be selected as resin, specifically including but not limited to one or a mixture of resins such as epoxy and its modified resins, polyurethane and its modified resins, acrylate and its modified resins, unsaturated polyester and its modified resins, etc.;

[0056] For the curing of the filling material described in step S300, one or more of baking curing, light curing, room temperature curing, etc. can be selected according to the selected resin type to make it cured and formed. After curing, the filling material needs to meet the conditions of hardness ≥ 5B, fineness ≤ 45um, and viscosity ≥ 2000mpa·s.

[0057] It should be noted that the main body of the filling material in this embodiment is the above-mentioned mixture of one or more resins. In the actual production process, the properties such as hardness, viscosity, and adhesion of the filling material will be adjusted by adding materials such as fillers, additives, and curing agents to the main body; the composite coating finally formed in this way can be used as a suitable filling material in the method proposed in this embodiment.

[0058] Preferably, to ensure the accurate printing position of the filling material, at least two positioning holes can be opened on the backing plate substrate to correspond to the positioning holes opened at the corresponding positions on the rigid-flex printed circuit board. After the corresponding positioning holes on the rigid-flex printed circuit board and the backing plate of the rigid-flex printed circuit board are aligned, the connection between the rigid-flex printed circuit board and the backing plate of the rigid-flex printed circuit board is fixed by positioning parts such as screws and pins, so that the resin printed on the backing plate of the rigid-flex printed circuit board can be better combined with the recessed area on the rigid-flex printed circuit board, thereby ensuring that the resin does not shift during printing and ensuring the qualification rate of drilling burrs;

[0059] The diameter of each positioning hole is preferably 2.0 - 3.5mm, and when the backing plate of the rigid-flex printed circuit board is attached to the rigid-flex printed circuit board, the positioning deviation between the backing plate of the rigid-flex printed circuit board and the corresponding positioning holes on the rigid-flex printed circuit board shall not be greater than 0.2mm.

[0060] It should be noted that since the flexible printed circuit board and the rigid printed circuit board used to make the rigid-flex printed circuit board have standard parameters, the information of the recessed area of the rigid-flex printed circuit board can be directly obtained based on the flexible printed circuit board and the rigid printed circuit board. See Figure 3 , the specific steps for obtaining the information of the recessed area of the rigid-flex printed circuit board described in step S100 include:

[0061] S110: Obtain information on the flexible printed circuit board and the rigid printed circuit board that make up the rigid-flex printed circuit board.

[0062] S120: Based on the information of the flexible printed circuit board and the rigid printed circuit board, obtain the information of the sunken area of the rigid-flex printed circuit board.

[0063] As mentioned above, the information of the sunken area includes the depth information of the sunken area, that is, the height difference of the sunken area. It should be noted that there may be a certain deviation between the actual height difference value obtained based on the flexible printed circuit board and the rigid printed circuit board and the theoretical value. Therefore, the height difference of the rigid-flex printed circuit board can be confirmed by actual measurement;

[0064] Furthermore, the combination process of the rigid-flex printed circuit board can be optimized by sampling inspection or comprehensive inspection. The specific operation method can be: select a certain number of rigid-flex printed circuit boards for actual measurement, compare the actual measurement results with the information of the sunken area estimated based on the parameters of the flexible printed circuit board and the rigid printed circuit board, evaluate the error situation, and when it is found that the error based on parameter estimation is greater than the preset threshold, correct or improve the method of combining the flexible printed circuit board and the rigid printed circuit board into a rigid-flex printed circuit board based on the actual measurement results to improve the accuracy of the information of the sunken area.

[0065] Preferably, referring to Figure 4 , step S200 is implemented through a graphic screen corresponding to the sunken area of the rigid-flex printed circuit board. The method of making the graphic screen specifically includes:

[0066] S210: Make a film image based on the information of the sunken area.

[0067] S220: After the film image is attached to the screen frame, expose the screen frame to obtain the graphic screen.

[0068] Specifically, referring to Figure 5 、 Figure 6 , in this embodiment, resin is coated on the printing area through a screen printing machine. After obtaining the graphic screen, the backing substrate can be fixed on the screen printing table of the screen printing machine according to the positioning holes on the backing substrate, and the screen printing machine can coat resin on each printing area of the backing substrate based on the graphic screen; in this embodiment, the graphic screen is provided with a registration circle, and the position of the registration circle corresponds to the positioning holes on the backing substrate, which is used to fix the backing substrate on the screen printing table of the screen printing machine through the positioning holes; to achieve precise positioning of the graphic screen relative to the substrate and ensure the accuracy and consistency during the printing process, the diameter of the registration circle should be larger than the diameter of the corresponding positioning holes on the backing substrate, and the diameter difference between the registration circle and its corresponding positioning hole should not be greater than 1.0 mm. In this embodiment, the diameter difference between the registration circle and its corresponding positioning hole is preferably 0.2 - 1.0 mm.

[0069] It should be noted that the screen frame refers to a frame structure used on a printing-down machine, usually made of metal or plastic, with a flat surface and a fine grid structure. The function of the screen frame is to fix the film image on the printing-down machine for exposure. After the film image is attached to the screen frame, light can penetrate the open part of the film image to form the exposed graphic edge. The grid structure on the screen frame helps to keep the film image flat and ensures that the light does not shift or blur when passing through the film image;

[0070] Users can select a screen frame of appropriate size according to the size and requirements of the film image and place the film image accurately on the screen frame. The printing-down machine is provided with an adjustable clamping mechanism for fixing the film image, and the adjustable clamping mechanism can fix the entire screen frame in the exposure area of the printing-down machine for subsequent exposure processing.

[0071] Embodiment 2

[0072] In this embodiment, the rigid-flex board is pre-set with 3 positioning holes, and the method proposed in Embodiment 1 is applied to manufacture the rigid-flex board backing plate, which specifically includes the following steps:

[0073] Drill 3 positioning holes at the corresponding positions of the 0.2mm aluminum sheet according to the positioning holes of the rigid-flex board, so that when drilling on the rigid-flex board, the rigid-flex board backing plate can be inlaid under the rigid-flex board through the positioning holes;

[0074] Make a screen plate according to the data of the recessed area of the rigid-flex board, and fix the 0.2mm aluminum sheet on the screen printing table through the positioning holes;

[0075] Select an epoxy-modified resin as the main resin, and mix it with fillers, curing agents, and additives to prepare a resin with a viscosity of 8000 mPa·s, a hardness of 3B, and a fineness of 30 μm. Screen-print the prepared resin on the surface of the 0.2mm aluminum sheet with a thickness of 50 μm, and bake it at a high temperature of 100 °C for 20 min to obtain the rigid-flex board backing plate ①.

[0076] In the rigid-flex board backing plate ① prepared by the method provided in this embodiment, the pencil hardness of the resin is 3B, the thickness is 50 μm, and the tip length of the burrs that appear after drilling is 16.65 μm.

[0077] It should be noted that B is one of the pencil hardness units, usually used to describe the hardness of the graphite core of a pencil, representing different hardness grades of the graphite core. In this embodiment, it is used to describe the ability of the rigid-flex board backing plate to resist external force deformation or scratches. The softer the pencil hardness, the easier the rigid-flex board backing plate is to deform under external force, and the harder the pencil hardness, the less likely it is to deform under external force.

[0078] The pencil hardness ranges from soft to hard as follows: 10B, 9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, 10H; among them, 10B is the softest pencil hardness and 10H is the hardest pencil hardness.

[0079] Example 3

[0080] In this embodiment, the rigid-flex board is pre-set with 3 positioning holes, and the method proposed in Example 1 is applied to manufacture the rigid-flex board backing plate, which specifically includes the following steps:

[0081] Drill 3 positioning holes at the corresponding positions of the 0.3mm cold punching plate according to the positioning holes of the rigid-flex board, so that when drilling holes in the rigid-flex board, the rigid-flex board backing plate can be inlaid under the rigid-flex board through the positioning holes;

[0082] Make a stencil according to the data of the sunken area of the rigid-flex board, and fix the 0.3mm cold punching plate on the screen printing table through the positioning holes;

[0083] Select a modified acrylate resin as the main resin, and mix it with fillers, curing agents, and additives to prepare a resin with a viscosity of 12000mpa·s, a hardness of B, and a fineness of 25um. Screen-print the prepared resin on the surface of the 0.3mm cold punching plate with a thickness of 50um, and cure it through a UV machine to obtain the rigid-flex board backing plate ②.

[0084] In the rigid-flex board backing plate ② obtained by the method provided in this embodiment, the pencil hardness of the resin is B, the thickness is 50um, and the tip length of the burrs that appear after drilling is 11.22um.

[0085] It should be noted that the cold punching plate, also known as the phenolic plate, is a laminated cardboard made by impregnating cellulose fiber paper with phenolic resin and hot-pressing. The cold punching plate has good punching and shearing performance at room temperature, as well as good electrical performance and heat resistance;

[0086] The UV machine is a device that uses ultraviolet curing technology. The UV machine usually includes an ultraviolet lamp and a control system. In this embodiment, the UV machine cures the resin by means of ultraviolet irradiation. Ultraviolet rays can quickly cure the resin and make it a solid rigid-flex board backing plate for subsequent drilling processes.

[0087] Example 4

[0088] In this embodiment, the rigid-flex board is pre-set with 3 positioning holes, and the method proposed in Example 1 is applied to manufacture the rigid-flex board backing plate, which specifically includes the following steps:

[0089] According to the positioning holes on the rigid-flex board, drill 3 positioning holes at the corresponding positions on the 0.3mm cold punching board, so that when drilling on the rigid-flex board, the backing plate of the rigid-flex board can be inlaid under the rigid-flex board through the positioning holes;

[0090] Make a stencil according to the data of the sunken area of the rigid-flex board, and fix the 0.3mm cold punching board on the screen printing table through the positioning holes;

[0091] Select a polyurethane-modified acrylate resin as the main resin, and mix it with fillers, curing agents, and additives to prepare a resin with a viscosity of 20000 mpa·s, a hardness of F, and a fineness of 30um. Screen-print the prepared resin on the surface of the 0.3mm cold punching board with a thickness of 50um, and cure it through a UV machine to obtain the backing plate ③ of the rigid-flex board.

[0092] In the backing plate ③ of the rigid-flex board prepared by the method provided in this embodiment, the pencil hardness of the resin is F, the thickness is 50um, and the tip length of the burrs that appear after drilling is 11.53um.

[0093] Based on the results obtained from the method steps of Embodiments 2-4 proposed in this solution, a comparison is made with the effects of directly using a cold punching board as the backing plate of the rigid-flex board in the prior art. The experimental results are shown in Table 1:

[0094] Comparison Table of Drilling Burrs - Table 1

[0095] Backing plate Pencil hardness Thickness Burr Cold punching plate 68.21um Backing plate ① for rigid-flex board 3B 50um 16.65um Backing plate ② for rigid-flex board B 50um 11.22um Backing plate ③ for rigid-flex board F 50um 11.53um

[0096] Embodiment 5

[0097] This embodiment proposes a backing plate for a rigid-flex board, which is used to cooperate with the drilling process of a rigid-flex board composed of a flexible circuit board and a rigid circuit board. This backing plate of the rigid-flex board is obtained by the manufacturing method of the backing plate of the rigid-flex board proposed in Embodiment 1.

[0098] In summary, the present invention provides a backing plate for a rigid-flex board and its manufacturing method. This solution is simple to use and has a low cost. It can effectively suppress the burrs that appear during the drilling process. Compared with the method of suppressing flash by coating in the prior art, this solution can increase the production efficiency without adding new processes and equipment, and will not cause damage to the circuit board itself.

[0099] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a backing plate for a rigid-flex printed circuit board, characterized in that, the backing plate for the rigid-flex printed circuit board obtained by the method is used to improve the drilling burrs caused by the height difference on the surface of the rigid-flex printed circuit board composed of a flexible printed circuit board and a rigid printed circuit board, and the method includes: obtaining the information of the concave areas of the rigid-flex printed circuit board; the concave area information includes the quantity information of the concave areas on the rigid-flex printed circuit board, the position information and size information of each concave area; determining the printing areas on the backing plate substrate based on the concave area information; the area of each printing area is not less than the area of the drilling area and not greater than the area of the corresponding concave area; coating a filling material on the printing areas on the backing plate substrate and curing the filling material to obtain the backing plate for the rigid-flex printed circuit board after the filling material is cured.

2. The method according to claim 1, characterized in that, the obtaining the information of the concave areas of the rigid-flex printed circuit board includes: obtaining the information of the flexible printed circuit board and the rigid printed circuit board that make up the rigid-flex printed circuit board; based on the information of the flexible printed circuit board and the rigid printed circuit board, obtaining the information of the concave areas of the rigid-flex printed circuit board.

3. The method according to claim 1 or 2, characterized in that, the determining the printing areas on the backing plate substrate based on the concave area information includes: making a film pattern based on the concave area information; after the film pattern is attached to the screen frame, exposing the screen frame to obtain a graphic screen plate; determining the printing areas on the backing plate substrate through the graphic screen plate.

4. The method according to claim 3, characterized in that, the method further includes: opening at least two positioning holes on the backing plate substrate to correspond to the positioning holes opened at the corresponding positions on the rigid-flex printed circuit board, and correspondingly setting positioning rings at the positions of the graphic screen plate corresponding to the positioning holes on the backing plate substrate; the diameter of each positioning hole is 2.0 - 3.5 mm, the diameter of the positioning ring is larger than the corresponding positioning hole, and the diameter difference between the positioning ring and the corresponding positioning hole is not greater than 1.0 mm.

5. The method according to claim 1, characterized in that, the thickness of the filling material coated on the printing areas of the backing plate substrate is 90% - 130% of the depth of the corresponding concave areas of the printing areas.

6. The method according to claim 1, characterized in that, the filling material includes a mixture of one or more resins such as epoxy and its modified resins, polyurethane and its modified resins, acrylate and its modified resins, unsaturated polyester and its modified resins.

7. The method according to claim 1 or 6, characterized in that, the curing the filling material includes: determining the type of the filling material, and selecting one or more of baking curing, light curing, and room temperature curing based on the type of the filling material to cure and mold the filling material so that the cured filling material meets the conditions of a hardness not less than 5B, a fineness not greater than 45 um, and a viscosity not less than 2000 mPa·s.

8. The method according to claim 1, characterized in that, The backing plate substrate includes aluminum sheet, PET, cold stamping plate, epoxy board, PP, PVC, acrylic board or iron sheet.

9. According to the method described in claim 8, characterized in that, the backing plate substrate includes PET, cold stamping plate or aluminum sheet with a thickness of 0.01 - 3 mm.

10. A flexible - rigid combined board backing plate, characterized in that, the flexible - rigid combined board backing plate is prepared by the method according to any one of claims 1 - 9.

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