Manufacturing method of step rigid-flex circuit board, step rigid-flex circuit board and electronic product

Abstract

The invention discloses a manufacturing method of a step rigid-flex circuit board, the step rigid-flex circuit board and an electronic product, and relates to the field of circuit boards and electronic products. The target soft board inner-layer core board is a soft board inner-layer core board in which a corresponding bonding pad and a windowing pattern are formed in advance according to the target design; the hard board core board and the multiple target soft board inner-layer core boards are sequentially stacked according to the design layers and laminated, and a multi-stage rigid-flexible circuit board is obtained; and on the basis of the bonding pad and the windowing pattern, sequentially forming a multi-stage stepped section of which the step windowing size is increased layer by layer on an inner core board of a target flexible board of the multi-stage rigid-flex circuit board through a laser processing technology, so as to obtain the stepped rigid-flex circuit board. The problem that the step height and the section thickness of the rigid-flex circuit board with the hard board step are relatively high is effectively avoided, and the requirements of high-density interconnection and miniaturization design are met.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards and electronic products, and in particular to a method for manufacturing a stepped rigid-flexible circuit board, a stepped rigid-flexible circuit board and an electronic product. Background Art

[0002] As electronic products and industrial equipment develop toward lightweighting, miniaturization, and high speed, existing printed circuit boards (PCBs) are typically formed by laminating multiple layers of rigid core board and dielectric layers (such as FR4 epoxy glass fiber board + prepreg, i.e., FR4 board + PP). PCBs that are machine-controlled-depth milled to create a stepped structure are called rigid-flex-rigid-board (R-R-F). However, due to the thick interlayer dielectric layer, this rigid-flex-rigid-board (R-R-F) PCB exhibits high step heights and profile thicknesses, making it difficult to meet the design requirements of high-density interconnects. Summary of the Invention

[0003] The present invention provides a method for manufacturing a stepped rigid-flexible circuit board, a stepped rigid-flexible circuit board and an electronic product, so as to solve the technical problem that the existing hard board stepped rigid-flexible circuit board has a high step height and a high cross-sectional thickness due to the large thickness of the interlayer dielectric layer.

[0004] In a first aspect, a method for manufacturing a stepped rigid-flex circuit board is provided, comprising: Providing a hard board core board and a plurality of target soft board inner core boards, wherein the target soft board inner core boards are soft board inner core boards with corresponding pads and window patterns formed in advance according to the target design; The rigid board core board and a plurality of target soft board inner core boards are sequentially stacked and laminated according to the design level to obtain a multi-level rigid-flexible circuit board; Based on the solder pads and the window patterns, a multi-level stepped profile with gradually increasing step window sizes is sequentially formed on the target soft board inner core board of the multi-level rigid-flexible circuit board through a laser processing process to obtain a stepped rigid-flexible circuit board.

[0005] In a second aspect, a step rigid-flexible circuit board is provided, wherein the step rigid-flexible circuit board is manufactured using the manufacturing method of the step rigid-flexible circuit board described in the first aspect.

[0006] In a third aspect, an electronic product is provided, comprising the stepped rigid-flex circuit board described in the second aspect.

[0007] The effect of a technical solution provided by the present invention is: by replacing the inner layer of the hard board core board with a thinner soft board core board (soft board inner core board), the hard board core board and multiple soft board inner core boards are accurately overlapped according to the design level, and based on the pad and window pattern, a laser processing technology is used to sequentially form a multi-level stepped profile with increasing step window size on the target soft board inner core board of the multi-level rigid-flexible circuit board, so that the formed step height and profile thickness are relatively thin, effectively avoiding the problem of high step height and profile thickness of the hard board step rigid-flexible circuit board, and meeting the requirements of high-density interconnection and miniaturization design. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0009] Figure 1 is a cross-sectional view of a conventional stepped rigid-flex circuit board in one embodiment of the present invention; Figure 2 is a flow chart of a method for manufacturing a stepped rigid-flex circuit board according to one embodiment of the present invention; Figure 3 1 is a schematic diagram of a finished product of a stepped rigid-flex circuit board according to one embodiment of the present invention; Figure 4 is a cross-sectional view of an inner core board of a target soft board in one embodiment of the present invention; Figure 5 is a cross-sectional view of a laminate according to an embodiment of the present invention; Figure 6 This is a cross-sectional view of an intermediate process of a multi-level rigid-flex circuit board according to one embodiment of the present invention; Figure 7 is a cross-sectional view of a stepped rigid-flex circuit board according to one embodiment of the present invention; Figure 8 Schematic diagram of the target soft board inner core board in one embodiment of the present invention.

[0010] The reference numerals are as follows: 1. Rigid board core; 2. Dielectric layer; 3. Target flexible board inner core; 31. First target flexible board inner core; 32. Second target flexible board inner core; 33. Third target flexible board inner core; 4. Laminate; 5. Pad area. DETAILED DESCRIPTION

[0011] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0012] In order to understand the prior art more clearly, Figure 1 To recap the existing technology, existing printed circuit boards are typically formed by laminating multiple layers of rigid core board (1) and dielectric layer (2) (e.g., FR4 epoxy resin fiberglass board + prepreg, i.e., FR4 board + PP). A rigid-flex-stairs rigid-flex circuit board (PCB) is a PCB that is machine-milled to form a stepped structure. However, due to the thick interlayer dielectric layer, this rigid-flex-stairs rigid-flex circuit board has a high step height and profile thickness, making it difficult to meet the design requirements of high-density interconnects.

[0013] To better understand the inventive concept of this application, a comparative analysis of rigid and flexible boards is presented below. Specifically, the following analysis explains why replacing traditional rigid core boards (e.g., FR4 epoxy fiberglass boards (FR4 sheets)) with flexible core boards (e.g., flexible adhesive-backed copper foil (FRCC) or flexible printed circuit boards (FPC)) can overcome the bottleneck of existing step-rigid-flex circuit boards: First, the thickness of a single FR4 sheet is typically over 0.2-0.5mm. The interlayer dielectric thickness after a single step is relatively high (≥0.2mm), resulting in a high dielectric constant, which causes significant reflection and attenuation of high-speed signals at the step. However, the PI film thickness of FPC / FRCC can be as low as 0.025-0.1mm. Even with multiple steps after stacking multiple sheets, the overall interlayer dielectric thickness can be controlled to ≤0.15mm. This fundamentally reduces the dielectric layer thickness, minimizes signal delay and reflection, and improves bandwidth and signal integrity.

[0014] Secondly, when mechanically controlled-depth milling FR4 sheets, tool vibration and the high material hardness can easily cause microcracks, burrs, and stress concentration. The step edge roughness is high and difficult to stably control in batches, affecting solder joint strength and long-term reliability. However, the PI layer of FPC / FRCC is tightly bonded to the copper foil, and the material is flexible. Combined with laser (LCM) milling, it can quickly remove the resin and copper layers with micron-level precision, eliminating mechanical contact. The resulting smooth edges are highly repeatable, eliminating stress concentration points, and ensuring that the pad and step edges are flat and reliable.

[0015] Third, creating multiple steps on FR4 requires multiple tool changes or segmented milling, which is prone to cumulative errors. Furthermore, the thickness of each milling step is limited by the thinnest controllable depth of the sheet. However, after stacking multiple FPC / FRCC sheets and etching them layer by layer using a single laser process, the size of each window can be precisely set and gradually enlarged, unrestricted by tool diameter and material hardness, enabling the creation of any number of ultra-thin step structures.

[0016] Fourthly, FR4 sheets are very rigid and lack foldability, and the stepped areas cannot achieve spatial bending or dynamic stress dispersion. However, FPC / FRCC is inherently foldable, and the multi-level stepped areas of the flexible board can conform to stress distribution when folded, reducing the risk of cracking while meeting design requirements such as space compression and dynamic wiring.

[0017] In summary, replacing the traditional rigid core board with a flexible core board effectively solves the technical problem of the existing rigid-flexible circuit board with a high step height and profile thickness due to the large thickness of the interlayer dielectric layer.

[0018] It should be understood that this application uses soft board core board to replace traditional hard board core board, and the steps, processing parameters and processing methods of the processing steps are changed, breaking the conventional thinking. Figures 2 to 8 The following description provides detailed structures and steps to illustrate the technical solutions proposed by the present invention in detail.

[0019] First, as Figure 2 and Figure 3 As shown, a method for manufacturing a stepped rigid-flex circuit board is provided, comprising the following steps: S10, providing a hard board core board 1 and a plurality of target soft board inner core boards 3, wherein the target soft board inner core boards 3 are soft board inner core boards with corresponding pads and window patterns formed in advance according to a target design.

[0020] In this embodiment, the target soft board inner core board 3 includes a flexible adhesive-backed copper foil (FRCC) or a flexible printed circuit board (FPC).

[0021] Among them, Figure 4 As shown, the flexible adhesive-backed copper foil includes a polyimide (PI) substrate and copper foil. The flexible circuit board is a flexible structural circuit layer with a polyimide (PI) or polyester (PET) film as the substrate, a circuit pattern formed thereon and covered with a protective film.

[0022] The target thickness of the inner core 3 of the flexible board is 2.0 mil to 4.0 mil. Preferably, the target thickness of the inner core 3 of the flexible board can be 2.5 mil or 3.0 mil, which is not limited here. It should be understood that the thickness design of the target inner core 3 of the flexible board meets the height control requirements of the overall step profile, effectively reducing the height of the step profile formed after lamination.

[0023] As an example, the target flexible circuit board inner core board 3 is a flexible circuit board inner core board on which corresponding pads and window patterns are pre-formed according to the target design. It can be understood that according to the target design provided by the customer (for example, graphic data of the corresponding positions of the customer's graphic design), the design and positioning of pads (for example, IC pads and BGA pads, etc.) and window patterns (for example, step positions) are completed in advance on the flexible circuit board inner core board (such as FRCC or FPC) through processes such as photolithography and etching.

[0024] It should be understood that the multiple target soft board inner core boards 3 include two or more target soft board inner core boards 3. The specific number can be set according to the functional requirements and step structure level of the printed circuit board design, and the present invention does not limit it.

[0025] S20, stacking the hard board core board 1 and the plurality of target soft board inner core boards 3 in sequence according to the design levels and performing a lamination process to obtain a multi-level rigid-flexible circuit board.

[0026] In this embodiment, the temperature of the lamination treatment can be 80℃-150℃, the pressure can be 1.0kgf / cm²-5.0kgf / cm², and the duration can be 20 seconds-90 seconds. Preferably, the temperature can be 100℃, 110℃, 120℃ or 140℃, the pressure can be 2.0kgf / cm², 3.0kgf / cm² or 4.0kgf / cm², and the duration can be 30 seconds, 50 seconds, 65 seconds or 80 seconds, which are not limited here.

[0027] As an example, a hard board core board 1 and multiple target soft board inner core boards 3 with a thickness of 2.0 mil can be stacked on a lamination table in sequence according to the circuit design order, and placed in a hot press. The lamination is completed under the conditions of preset temperature and preset pressure for a preset time to obtain a multi-level rigid-flexible circuit board, thereby effectively reducing the step height and cross-section thickness while ensuring structural stability.

[0028] It should be understood that the preset temperature, preset pressure and preset time can be any value within the above-defined range and are not limited here.

[0029] S30. Based on the solder pads and the window pattern, a multi-level stepped profile with gradually increasing step window sizes is sequentially formed on the target soft board inner core board 3 of the multi-level rigid-flexible circuit board through a laser processing process to obtain the stepped rigid-flexible circuit board.

[0030] As an example, the positions of the solder pads and window patterns can first be determined. Then, during the laser processing process, the positions of the solder pads and window patterns on the inner core board 3 of the target flexible circuit board are laser processed layer by layer. For example, LCM laser milling is used to perform laser processing layer by layer, forming a stepped window structure that increases from top to bottom. This embodiment effectively eliminates the burrs and stress concentration caused by traditional mechanical milling, effectively improves the alignment accuracy of the solder pads and the reliability of the solder joints, meets the space utilization requirements of high-density interconnection and miniaturized design, and ensures that subsequent products can meet the design requirements of more compact and efficient products.

[0031] To sum up, the present invention provides a technical solution: by replacing the inner layer of the hard board core board with a thinner soft board core board (soft board inner core board), the hard board core board and multiple soft board inner core boards are accurately overlapped according to the design level, and based on the pad and window pattern, a laser processing technology is used to sequentially form a multi-level stepped profile with increasing step window size on the target soft board inner core board of the multi-level rigid-flexible circuit board, so that the formed step height and profile thickness are relatively thin, effectively avoiding the problem of high step height and profile thickness of the hard board step rigid-flexible circuit board, and meeting the requirements of high-density interconnection and miniaturization design.

[0032] In one embodiment, if Figure 5 As shown, in step S20, the plurality of target soft board inner core boards 3 include a first target soft board inner core board 31, a second target soft board inner core board 32 and a third target soft board inner core board 33; That is, the rigid board core board 1 and the plurality of target soft board inner core boards are stacked and laminated in sequence according to the design level to obtain a multi-level rigid-flexible circuit board, including the following steps: S21, using the hard board core board 1 as a base board, and arranging the first soft board inner core board on the base board, and performing a first lamination process to obtain a first-level rigid-flexible circuit board; S22, placing the second target flexible circuit board inner core board 32 on the first-level rigid-flex circuit board, and performing a second lamination process to obtain a second-level rigid-flex circuit board; S23, placing the third target soft board inner core board 33 on the secondary rigid-flex circuit board, and performing a third lamination process to obtain a laminate 4; S24, performing drilling, copper deposition, electroplating, pattern transfer and etching processes on the laminate 4 to obtain the multi-level rigid-flexible circuit board.

[0033] Drilling: refers to the use of mechanical drills or laser equipment to drill through holes or blind holes at predetermined locations on the laminate 4 to establish conductive connections between different layers (such as through-hole electroplating) or as an assembly positioning reference.

[0034] Copper deposition: refers to a process of depositing copper by chemical reduction reaction without power source, which is used to form a continuous thin layer of copper on the hole wall and surface, providing a conductive basis for subsequent electroplating.

[0035] Electroplating: refers to the process of further thickening the copper layer on the board surface and hole walls by electrolysis, which is used to enhance the conductivity and mechanical strength and ensure reliable electrical interconnection between multiple layers.

[0036] Pattern transfer: refers to the process of transferring the circuit design pattern onto copper foil using photolithography technology, including but not limited to film lamination, exposure, development and other steps, which are used to accurately form the circuit pattern in the required area.

[0037] Etching: refers to the use of chemical corrosive agents (such as ferric chloride and ammonium persulfate) to remove excess copper foil not covered by the photoresist film after the pattern is transferred, leaving only the required circuit pattern.

[0038] As an example, first, the hard board core board 1 can be placed on the lamination table, and the first target soft board inner core board 31 can be set on its surface. For example, the polyimide (PI layer) of the target soft board inner core board can be set on the upper surface of the hard board bottom layer, and the first preset temperature and the first preset pressure conditions are maintained for a first preset time to complete the first lamination process to obtain a first-level rigid-flexible circuit board, for example, the first lamination process is completed for 60 seconds at 180°C and 2.0kgf / cm²; then the second target soft board inner core board 32 is laid on the surface of the first-level rigid-flexible circuit board, for example, the PI layer of the second target soft board inner core board 32 can be set on the upper surface of the first target soft board inner core board 31, and the second preset temperature and the second preset pressure conditions are maintained for a second time. The second lamination process is completed for a preset time to obtain a secondary rigid-flexible circuit board. For example, the second lamination process is completed for 40 seconds at 150°C and 2.0kgf / cm². Then, a third target soft board inner core board 33 is laid on the secondary rigid-flexible circuit board. For example, the PI layer of the third target soft board inner core board 33 can be set on the upper surface of the third target soft board inner core board 33. The third lamination process is completed for a third preset time at a third preset temperature and a third preset pressure to obtain a secondary rigid-flexible circuit board. For example, the third lamination process is completed for 30 seconds at 150°C and 2.0kgf / cm². Finally, the obtained laminate 4 is subjected to drilling, copper plating, electroplating, pattern transfer and etching processes in sequence to obtain a multi-level rigid-flexible circuit board. In this embodiment, the close bonding and structural stability between each layer are ensured by layered and step-by-step lamination. At the same time, through precise subsequent processing steps, high-density interconnection design and miniaturization requirements are achieved, thereby improving the reliability and performance of subsequent products.

[0039] It should be understood that the target flexible board inner core board 3 is described as FRCC, which is only used as an example and does not constitute a limitation to the present invention.

[0040] In one embodiment, step S30, that is, based on the pads and the window pattern, a multi-step stepped cross-section with gradually increasing step window sizes is sequentially formed on the target flexible board inner core board 3 of the multi-step rigid-flex circuit board by a laser processing process to obtain the stepped rigid-flex circuit board, including the following steps: S31, based on the solder pads and the window pattern, sequentially forming a multi-step stepped cross-section with gradually increasing step window sizes on the target flexible board inner core board 3 of the multi-step rigid-flex circuit board by a laser processing process, so as to obtain a multi-step stepped structure; S32, performing degumming and surface coating treatment on the multi-step structure to obtain the step rigid-flexible circuit board.

[0041] In this embodiment, the debonding process is used to remove resin residues or glue residues remaining on the surface of the step area during the laser processing process, including but not limited to plasma cleaning, chemical debonding or wet cleaning.

[0042] Surface coating is used to cover the surface of the metal pad exposed by the step structure with a protective layer or functional layer (such as OSP, chemical nickel gold or immersion tin, etc.).

[0043] As an example, the positions of the pads and window patterns can be determined first. Then, during the laser processing process, the pads and window patterns on the inner core board 3 of the target flexible circuit board are laser processed layer by layer, forming a stepped window structure that increases from top to bottom, thereby obtaining a multi-step structure. Next, the multi-step structure is subjected to degumming and surface coating to obtain a stepped rigid-flex circuit board. In this embodiment, the degumming process ensures that no impurities remain in the cross-section area, effectively avoiding welding defects and short circuit risks. The surface coating further enhances the pads' antioxidant capacity and welding performance, effectively preventing oxidation failure and facilitating subsequent assembly processes such as chip soldering or component placement.

[0044] In one embodiment, if Figures 6 to 8 As shown, in step S31, based on the pad and the window pattern, a multi-step stepped cross-section with a gradually increasing step window size is sequentially formed on the target flexible board inner core board 3 of the multi-level rigid-flexible circuit board by a laser processing process to obtain a multi-step stepped structure, including the following steps: a. Determine the target window pattern area corresponding to the window pattern on the outermost target soft board inner core board 3 of the multi-stage rigid-flex circuit board; b. identifying the pad area 5 and the non-pad area of the pad 5 in the target window pattern area; c. respectively obtaining a first laser processing parameter corresponding to the pad area 5 and a second laser processing parameter corresponding to the non-pad area; d. Laser processing the pad area 5 on the inner core board 3 of the outermost target flexible board according to the first laser processing parameters, and laser processing the non-pad area on the inner core board 3 of the outermost target flexible board according to the second laser processing parameters to form a stepped profile; Subsequently, steps ad are repeated to sequentially process the target soft board inner core boards 3 below the multi-level rigid-flexible circuit board to form a multi-level stepped cross-section with gradually increasing step window sizes to obtain the multi-level stepped structure.

[0045] As an example, first, the target window pattern area corresponding to the window pattern on the outermost target soft board inner core board 3 of the multi-level rigid-flexible circuit board (for example, the third target soft board inner core board 33) can be determined, and the pad area 5 corresponding to the pad position and the non-pad area 5 can be removed from the target window pattern area; then, the first laser processing parameters corresponding to the pad area 5 and the second laser processing parameters corresponding to the non-pad area are respectively obtained, and the two types of areas are laser processed using the corresponding laser processing parameters to form a first-level stepped profile; then, the target soft board inner core boards 3 below are laser processed layer by layer according to the same steps, so that the window size of each layer increases successively, forming a multi-level stepped profile with the step window size increasing layer by layer, and obtaining a multi-level stepped structure. In this embodiment, the pad area 5 utilizes the first laser processing parameters to precisely control energy input, reduce the heat-affected zone, and avoid ablation or oxidation of the pad copper foil, ensuring pad dimensional accuracy and surface flatness, providing a high-quality interface for subsequent soldering. The non-pad area utilizes the second laser processing parameters to rapidly remove excess dielectric layer 2, improving processing efficiency while also preventing interference with adjacent pads caused by excessive processing. During layered processing, the window size is gradually increased, and parameter adaptation ensures the verticality of the sidewalls and inter-layer alignment accuracy of the multi-step structure, forming a smooth, transitional step profile. This reduces stress concentration, effectively improving pad alignment accuracy and solder joint reliability, and meeting the space utilization requirements of higher-density interconnects and miniaturized designs.

[0046] In one embodiment, the first laser processing parameters include: the number of scans is 8-10 times, and the scanning speed is 600mm / s-1000mm / s. Preferably, the number of scans can be 9 times, and the scanning speed can be 700mm / s, 800mm / s or 900mm / s.

[0047] In one embodiment, the second laser processing parameters include: the number of scans is 5-8 times, and the scanning speed is 600mm / s-1000mm / s. Preferably, the number of scans can be 6 or 7 times, and the scanning speed can be 700mm / s, 800mm / s or 900mm / s.

[0048] As shown in the table above: After processing the pad area 5 with parameters of 8-10 times and 600mm / s-1000 mm / s, the average Rz of the sample was about 0.73μm (good uniformity), and the PI layer residue rate was controlled between 1.5%-1.8%; after processing the non-pad area with parameters of 5-8 times and 600mm / s-1000 mm / s, the average Rz of the sample was about 0.82μm, and the PI layer residue rate was controlled between 1.7%-2.0%; the design indicators of window profile smoothness Rz ≤ 0.8μm and PI layer residue rate ≤ 2% were met, thereby ensuring the smoothness and cleanliness of the step window area.

[0049] It should be understood that the energy of the laser processing process here is related to each laser processing equipment and is a fixed value. Therefore, when selecting the corresponding laser processing parameters, you can choose according to the settings of each laser processing equipment, and there is no limitation here.

[0050] In one embodiment, if Figure 6 and Figure 8 As shown, in step d, that is, laser processing the pad area 5 on the inner core board 3 of the outermost target soft board according to the first laser processing parameters, the following steps are included: d1. According to the first processing path and the first processing area, laser processing is performed on the pad area 5 on the outermost target soft board inner core board 3 (for example, the third target soft board inner core board 33) according to the first laser processing parameters, wherein the first processing area is less than or equal to a first preset size relative to a single side of the pad area 5.

[0051] In this embodiment, the first processing path refers to the trajectory of the laser beam moving along a specific route during the laser processing process. It can be pre-designed according to the geometric shape of the processing area (such as welding pads, window patterns, etc.) to ensure that the laser can effectively cover the entire area and avoid damaging the surrounding unprocessed areas.

[0052] When the processing area is less than or equal to the first preset size relative to a single side of the pad area 5, the processing area is reduced by the first preset size (e.g., 1 mil) on each side of the pad area 5. For example, if the pad area 5 is originally 5 mil in length and width, and each side is reduced by 1 mil, the length and width become 3 mils, resulting in a processing area length and width of 3 mil × 3 mil. It's important to understand that, since a 5 mil side is reduced by 1 mil, both sides are reduced, resulting in a total reduction of 1 × 2 = 2 mils. The remaining length is then 5 − 2 = 3 mils.

[0053] In this embodiment, by laser processing the pad area 5 on the inner core board 3 of the outermost target soft board according to the first processing path and the first processing area and the first laser processing parameters, it is ensured that the laser path during the processing will not be too close to the edge of the pad, thereby avoiding damage to the pad area 5 or unnecessary material removal, and ensuring the integrity and accuracy of the pad area 5.

[0054] It should be understood that the first preset size of 1 mil is only an example and can also be 0.8 mil or 1.2 mil, etc. The specific size can be preset according to actual needs and is not limited here.

[0055] That is, the laser processing of the non-pad area on the inner core board 3 of the outermost target flexible board according to the second laser processing parameters includes the following steps: d2. According to the second processing path and the second processing area, laser processing is performed on the non-pad area on the inner core board 3 of the outermost target soft board according to the second laser processing parameters, wherein the second processing area is less than or equal to a second preset size relative to a single side of the non-pad area.

[0056] In this embodiment, the limitation of the second processing path can refer to the limitation of the first processing path, the limitation of the second processing area can refer to the limitation of the first processing area, and the limitation of the second preset size can refer to the limitation of the second preset size. In order to avoid repetition, they will not be repeated here.

[0057] It should be understood that the second preset size and the first preset size may be the same or different, and may be specifically set as needed, which is not limited here.

[0058] As an example, according to the second processing path and the second processing area, the non-pad area on the outermost target soft board inner core board 3 (for example, the third target soft board inner core board 33) is laser processed according to the second laser processing parameters, ensuring precise control during the laser processing process, avoiding the laser beam from contacting the pad area or other surrounding areas, achieving precise processing of the non-pad area, and protecting the structure of the entire printed circuit board.

[0059] In a second aspect, a step rigid-flexible circuit board is provided, wherein the step rigid-flexible circuit board is manufactured using the manufacturing method of the step rigid-flexible circuit board described in the first aspect.

[0060] In a third aspect, an electronic product is provided, comprising the stepped rigid-flex circuit board described in the second aspect.

[0061] In the description of the present invention, the stepped rigid-flex circuit board may also be a stepped printed circuit board or other stepped circuit boards, which are not limited here.

[0062] In the description of the present invention, multiple refers to two or more.

[0063] In the description of the present invention, the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0064] In the description of the present invention, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0065] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a stepped rigid-flex circuit board, characterized in that: include: Providing a hard board core board and a plurality of target soft board inner core boards, wherein the target soft board inner core boards are soft board inner core boards with corresponding pads and window patterns formed in advance according to the target design; The rigid board core board and a plurality of target soft board inner core boards are sequentially stacked and laminated according to the design level to obtain a multi-level rigid-flexible circuit board; Based on the solder pads and the window patterns, a multi-level stepped profile with gradually increasing step window sizes is sequentially formed on the target soft board inner core board of the multi-level rigid-flexible circuit board through a laser processing process to obtain a stepped rigid-flexible circuit board.

2. The method for manufacturing a stepped rigid-flex circuit board according to claim 1, wherein: The plurality of target soft board inner core boards include a first target soft board inner core board, a second target soft board inner core board and a third target soft board inner core board; The hard board core board and a plurality of target soft board inner core boards are sequentially stacked and laminated according to the design level to obtain a multi-level rigid-flexible circuit board, including: The rigid board core board is used as a base board, and the first target soft board inner core board is arranged on the base board, and a first lamination process is performed to obtain a first-level rigid-flex circuit board; Arranging the second target soft board inner core board on the first-level rigid-flex circuit board and performing a second lamination process to obtain a second-level rigid-flex circuit board; Arranging the third target soft board inner core board on the secondary rigid-flex circuit board and performing a third lamination process to obtain a laminate; The laminate is subjected to drilling, copper deposition, electroplating, pattern transfer and etching processes to obtain the multi-level rigid-flexible circuit board.

3. The method for manufacturing a stepped rigid-flex circuit board according to claim 1, wherein: Based on the pads and the window patterns, a multi-stepped cross-section with gradually increasing step window sizes is sequentially formed on the target flexible board inner core board of the multi-step rigid-flex circuit board through a laser processing process to obtain the stepped rigid-flex circuit board, including: Based on the solder pads and the window pattern, a multi-step stepped cross-section with gradually increasing step window sizes is sequentially formed on the target flexible board inner core board of the multi-step rigid-flex circuit board by a laser processing process to obtain a multi-step stepped structure; The multi-step structure is subjected to degumming and surface coating treatment to obtain the step rigid-flex circuit board.

4. The method for manufacturing a stepped rigid-flex circuit board according to claim 3, wherein: Based on the pads and the window patterns, a multi-level stepped cross-section with gradually increasing step window sizes is sequentially formed on the target flexible board inner core board of the multi-level rigid-flexible circuit board through a laser processing process to obtain a multi-level stepped structure, including: a. Determine a target window pattern area corresponding to the window pattern on the inner core board of the outermost target flexible board of the multi-level rigid-flexible circuit board; b. identifying a pad area and a non-pad area of the pad in the target window pattern area; c. respectively acquiring a first laser processing parameter corresponding to the pad area and a second laser processing parameter corresponding to the non-pad area; d. Laser processing the pad area on the inner core board of the outermost target flexible board according to the first laser processing parameters, and laser processing the non-pad area on the inner core board of the outermost target flexible board according to the second laser processing parameters to form a first-level stepped profile; Subsequently, steps ad are repeated to sequentially process the inner core boards of each target flexible board below the multi-level rigid-flexible circuit board to form a multi-level stepped cross-section with gradually increasing step window sizes to obtain the multi-level stepped structure.

5. The method for manufacturing a stepped rigid-flex circuit board according to claim 4, wherein: The laser processing of the pad area on the inner core board of the outermost target flexible board according to the first laser processing parameters includes: Laser processing is performed on the pad area on the inner core board of the outermost target flexible board according to the first processing path and the first processing area according to the first laser processing parameters, wherein the first processing area is smaller than or equal to a first preset size relative to a single side of the pad area; The laser processing of the non-pad area on the inner core board of the outermost target flexible board according to the second laser processing parameters includes: According to the second processing path and the second processing area, the non-pad area on the inner core board of the outermost target soft board is laser processed according to the second laser processing parameters, wherein the single side of the second processing area relative to the non-pad area is less than or equal to a second preset size.

6. The method for manufacturing a stepped rigid-flex circuit board according to claim 4 or 5, characterized in that: The first laser processing parameters include: scanning times of 8 to 10 times, and scanning speed of 600 mm / s to 1000 mm / s; and / or, The second laser processing parameters include: scanning times of 5 to 8 times, and scanning speed of 600 mm / s to 1000 mm / s.

7. The method for manufacturing a stepped rigid-flex circuit board according to any one of claims 1 to 5, characterized in that: The thickness of the inner core board of the target soft board is 2.0 mil-4.0 mil.

8. The method for manufacturing a stepped rigid-flex circuit board according to any one of claims 1 to 5, characterized in that: The target soft board inner core board includes a flexible adhesive-backed copper foil or a flexible circuit board.

9. A step rigid-flex circuit board, characterized in that: The stepped rigid-flex circuit board is manufactured by the method for manufacturing a stepped rigid-flex circuit board according to any one of claims 1 to 8.

10. An electronic product, characterized in that: The electronic product includes the stepped rigid-flex circuit board according to claim 9.

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