A method for controlling the flatness of reinforcing steel sheets pressed into RFPC boards

Abstract

This invention relates to the field of RFPC board manufacturing technology and discloses a method for controlling the flatness of RFPC board reinforcing steel sheet pressing. This method is used to press different reinforcing steel sheets with a thickness difference greater than 0.1 mm onto the same RFPC board. The method includes the following steps: providing an RFPC substrate, the substrate having a first mounting area and a second mounting area; pressing a first reinforcing steel sheet with a first thickness in the first mounting area using a hard pressing process; and pressing a second reinforcing steel sheet with a second thickness in the second mounting area using a hard pressing process, wherein the second thickness is greater than the first thickness, and the difference between the first and second thicknesses is greater than 0.1 mm. The purpose of this invention is to solve the problem that the flatness after pressing easily exceeds specifications when two reinforcing steel sheets of different thicknesses are needed at the head and tail of the RFPC board with a large thickness difference.

Description

Technical Field

[0001] This invention relates to the field of RFPC board manufacturing technology, specifically to a method for controlling the flatness of RFPC board reinforcing steel sheet pressing. Background Technology

[0002] During the manufacturing process of RFPC boards, reinforcing components are typically attached and pressed into specific areas of the board. Subsequent processes involve leveling the board surface to improve overall rigidity and enhance dimensional and forming stability. Because the structural support and assembly requirements of the head and tail sections often differ, different thicknesses of reinforcing steel sheets are used for each section to achieve differentiated reinforcement effects and meet the functional requirements of different areas. In this type of processing, the method of attaching the reinforcing steel sheets and the subsequent leveling must be coordinated to ensure consistency in the finished product.

[0003] However, when using reinforcing steel sheets with significant differences in thickness at the head and tail, the existing process is not capable of controlling the deformation of the sheet after lamination, which can easily lead to problems such as substandard flatness of the finished product (e.g., warping or uneven deformation), resulting in the risk of the RFPC board exceeding the specification limits in subsequent installation or inspection stages. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the flatness of RFPC boards is prone to exceed specifications when two reinforcing steel sheets of different thicknesses are attached / pressed at the head and tail of the board and the thickness difference is large. Therefore, this invention proposes a method for controlling the flatness of RFPC board reinforcing steel sheet pressing.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for controlling the flatness of reinforcing steel sheets pressed onto an RFPC board, used for bonding different reinforcing steel sheets with a thickness difference greater than 0.1 mm onto the same RFPC board, includes the following steps: An RFPC substrate is provided, the substrate having a first mounting area and a second mounting area; In the first mounting area, a first reinforcing steel sheet of a first thickness is pressed onto the mounting area using a hard pressing process; In the second mounting area, a second reinforcing steel sheet with a second thickness is pressed by a hard pressing process. The second thickness is greater than the first thickness, and the difference between the first thickness and the second thickness is greater than 0.1 mm. The pressing step of the first reinforcing steel sheet is performed before the pressing step of the second reinforcing steel sheet; After the first and second reinforcing steel sheets are attached, the RFPC substrate and the reinforcing steel sheets thereon are leveled together.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the first mounting area is the head region of the RFPC board, and the second mounting area is the tail region of the RFPC board. The first thickness is 0.12 mm, and the second thickness is not less than 0.25 mm.

[0008] Furthermore, the hard pressing process for applying the first reinforcing steel sheet and the second reinforcing steel sheet is carried out under heating and pressurization conditions, wherein the pressure when applying the first reinforcing steel sheet is 10-20 kg / cm² and the temperature is 160-180℃. The pressure when applying the second reinforcing steel sheet is 15-25 kg / cm², and the temperature is 160-180℃.

[0009] Furthermore, the leveling process is either roller leveling or flat die leveling, with a leveling temperature ranging from room temperature to 150°C and a leveling pressure of 5-15 kg / cm².

[0010] Furthermore, the RFPC substrate is not flattened before the first reinforcing steel sheet is applied. The leveling process only occurs after all reinforcing steel sheets have been applied.

[0011] Furthermore, both the first and second reinforcing steel sheets are stainless steel reinforcing sheets, and are attached to the RFPC substrate by a thermosetting adhesive layer. Under the hard pressing process, the thermosetting adhesive layer is cured by heat.

[0012] Furthermore, the RFPC substrate is an RFPC board for a camera module, and the first mounting area is a Holder area; wherein, by controlling the pressure, temperature and time of the leveling process, the flatness of the first mounting area after leveling is ≤45μm.

[0013] Furthermore, the first reinforcing steel sheet and the second reinforcing steel sheet are pressed together in the following order: First, place the first reinforcing steel sheet in the first mounting area of ​​the RFPC substrate and perform hard pressing; After the first reinforcing steel sheet is applied, the second reinforcing steel sheet is placed in the second mounting area and hard pressing is performed. No leveling or other stress-relieving treatment is performed on the RFPC substrate between the two bonding steps.

[0014] Furthermore, the leveling process specifically involves placing the RFPC substrate with the first and second reinforcing steel sheets attached in a leveling fixture, applying pressure under heating conditions, and holding it for 5-30 seconds.

[0015] Furthermore, after the second reinforcing steel sheet is applied, the RFPC substrate is first cooled before the leveling process is performed.

[0016] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: This invention achieves more targeted control over deformation mechanisms by partitioning and pressing reinforcing steel sheets with thickness differences greater than 0.1 mm onto the same RFPC board, and then performing the pressing and leveling in stages. The substrate is divided into first and second mounting areas. In the first mounting area, a steel sheet of the first thickness is first pressed using a hard-press process to establish local support and prepare for subsequent deformation. Then, in the second mounting area, a steel sheet of the second thickness, greater than the first thickness and with a difference greater than 0.1 mm, is pressed and pressed onto the substrate. This sequential pressing reduces stress abrupt changes and uneven warping tendencies caused by the cumulative thickness difference. Finally, the substrate and its two reinforcing steel sheets are leveled as a whole, ensuring that residual deformation after pressing is corrected within the same controlled process. This improves the overall flatness stability and consistency, reducing the risk of flatness exceeding limits during assembly or inspection. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall method steps of the present invention; Figure 2 This is a schematic diagram of the partitioning and pressing sequence of the present invention; Figure 3 This is a schematic diagram of the hard pressing process parameters of the present invention; Figure 4 This is a schematic diagram of the leveling process of the present invention; Figure 5 This is a schematic diagram illustrating the bonding and leveling sequence of the present invention; Figure 6 This is a schematic diagram of the leveling fixture operation of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This application relates to RFPC (Rigid-Flex Printed Circuit) board manufacturing technology, particularly a method for controlling the overall flatness of the board when mounting reinforcing steel sheets of significantly different thicknesses onto the same RFPC board. In traditional processes, when reinforcing steel sheets of significantly different thicknesses (e.g., a thickness difference exceeding 0.1 mm) need to be mounted on different functional areas of the RFPC board, such as the head and tail sections, the uneven stress distribution during the sequential mounting process can easily cause warping or uneven deformation of the substrate, ultimately resulting in the finished product failing to meet assembly and inspection requirements. To address this problem, this application provides a series of methods for controlling flatness. Through zoned mounting, step-by-step hard pressing, and final controlled flattening, the risk of stress abrupt changes and warping caused by thickness differences is effectively reduced, ensuring the dimensional consistency and reliability of the RFPC board in subsequent assembly.

[0020] This application provides a method for controlling the flatness of reinforcing steel sheets pressed onto an RFPC board, used for bonding different reinforcing steel sheets with a thickness difference greater than 0.1 mm onto the same RFPC board, comprising the following steps: providing an RFPC substrate, the substrate having a first mounting area and a second mounting area; bonding a first reinforcing steel sheet with a first thickness in the first mounting area by a hard pressing process; bonding a second reinforcing steel sheet with a second thickness in the second mounting area by a hard pressing process, the second thickness being greater than the first thickness, and the difference between the first thickness and the second thickness being greater than 0.1 mm; wherein the bonding step of the first reinforcing steel sheet is performed before the bonding step of the second reinforcing steel sheet; after completing the bonding of the first and second reinforcing steel sheets, the RFPC substrate together with the reinforcing steel sheets thereon is flattened.

[0021] In this method, such as Figure 1 As shown, a first mounting area and a second mounting area are first divided on the RFPC substrate, with each area corresponding to functional parts requiring different reinforcement stiffness. A thinner first reinforcing steel sheet is first pressed onto the first mounting area using a hard-pressing process. Due to its smaller thickness, the initial deformation of the substrate during pressing is limited, and this allows a stable support state to be established in this local area, laying the stress foundation for subsequent processes. Subsequently, a thicker second reinforcing steel sheet is hard-pressed onto the second mounting area. Since the first mounting area is already in a relatively stable, cured support state, it can effectively disperse and absorb the stress generated by the thicker sheet pressing, avoiding instantaneous stress concentration that could lead to severe local warping.

[0022] Since the difference between the first and second thicknesses was set to be greater than 0.1 mm, the thinner steel sheet was applied and positioned first, significantly suppressing the deformation tendency of the thicker sheet during subsequent application. Finally, the RFPC substrate with the two types of reinforcing steel sheets was flattened as a whole, so that the slight non-uniform deformation remaining in the thin-to-thickness application process was uniformly corrected within the same controlled process.

[0023] The method of this embodiment, such as Figure 2 As shown, by combining partitioning, a thin-to-thick pressing sequence with final overall leveling, progressive control of the pressing stress of reinforcing steel sheets of different thicknesses is achieved from the deformation mechanism perspective. This significantly reduces the stress mutation and uneven warping tendency caused by the superposition of thickness differences, and significantly improves the stability and consistency of the flatness of the finished RFPC board. In turn, it reduces the probability of quality risks due to warping deviations in subsequent installation or inspection stages.

[0024] In an optional embodiment of this application, the first mounting area is the head region of the RFPC board, and the second mounting area is the tail region of the RFPC board; the first thickness is 0.12mm, and the second thickness is not less than 0.25mm.

[0025] In practical applications, the head area of ​​an RFPC board is often used to connect precision components or as a holder area, and is extremely sensitive to the thickness and surface flatness of the reinforcing steel sheet, requiring thinner and higher precision reinforcement; while the tail area usually supports larger structural components such as connectors, requiring higher rigidity support, so thicker reinforcing steel sheets can be selected.

[0026] The first mounting area is defined as the head region and uses a thin steel sheet with a thickness of 0.12mm, while the second mounting area is defined as the tail region and uses a thick steel sheet with a thickness of not less than 0.25mm. The thickness difference reaches more than 0.13mm, far exceeding 0.1mm. During processing, the thin steel sheet at the head is first hard-pressed to fix the head region and form a stable low-stress support base. Then, the thick sheet is pressed onto the tail region. During this process, the already solidified area at the head can effectively resist the additional torque introduced by the thick sheet, preventing the head region from warping. This configuration can well meet the typical structure requiring differential reinforcement, such as RFPC boards for camera modules, so that the head and tail regions obtain matched support performance. At the same time, by using the pressing sequence of thinner to thicker, the deformation of the board caused by the thickness difference is controlled to an extremely low level. Finally, after leveling, the overall flatness performance is excellent.

[0027] In an optional embodiment of this application, the hard pressing process of applying the first reinforcing steel sheet and the second reinforcing steel sheet is carried out under heating and pressurization conditions. The pressure when applying the first reinforcing steel sheet is 10-20 kg / cm² and the temperature is 160-180°C. The pressure when applying the second reinforcing steel sheet is 15-25 kg / cm² and the temperature is 160-180°C.

[0028] The heating and pressurizing environment used in the hard pressing process allows the thermosetting adhesive layer between the reinforcing steel sheet and the substrate to fully soften, flow, and cure. For example... Figure 3 As shown, when applying the first reinforcing steel sheet, a relatively low pressure of 10-20 kg / cm² and a temperature of 160-180℃ are used. This ensures reliable adhesion of the thin steel sheet while avoiding excessive pressure that could cause excessive indentation or stress concentration in the thinner steel sheet area. When applying the second reinforcing steel sheet, due to the increased thickness and rigidity of the steel sheet, the pressure is appropriately increased to 15-25 kg / cm². This ensures that the adhesive layer is fully spread and cured under the thicker steel sheet, guaranteeing bonding strength. Maintaining the temperature at 160-180℃ allows the adhesive layer to cure steadily, preventing rebound after the pressure is removed.

[0029] This differentiated pressure setting, combined with a consistent temperature window, ensures that the internal stress of the board remains within a controllable range during both hard pressing processes, resulting in minimal overall deformation of the substrate. This provides a good initial condition for subsequent leveling, thereby improving the controllability of the final flatness and the yield of the finished product.

[0030] In one optional embodiment of this application, the leveling process is roller leveling or flat die leveling, the leveling temperature is room temperature to 150°C, and the leveling pressure is 5-15 kg / cm².

[0031] Depending on the production line configuration and product characteristics, leveling can be performed using either continuous roller pressing or flat die pressing. Roller pressing applies progressive pressure to the substrate surface using rollers, making it suitable for continuous batch operations; flat die pressing, on the other hand, ensures uniform stress across the entire board and provides better correction for localized deformations.

[0032] like Figure 4 As shown, the leveling temperature can be selected from room temperature to 150°C. Moderate heating can soften the substrate resin and reduce internal stress, thereby improving leveling efficiency. The pressure range is 5-15 kg / cm², which is sufficient to correct residual warping caused by bonding and to avoid damage or delamination to the bonded reinforcing steel sheet and RFPC substrate.

[0033] This gentle yet effective leveling operation can correct minor uneven deformations left by previous pressing of thin and thick steel sheets in one go, achieving a flatness of the sheet metal that meets the requirements of high-precision assembly.

[0034] In an optional embodiment of this application, the RFPC substrate is not leveled before the first reinforcing steel sheet is applied; leveling only occurs after all reinforcing steel sheets have been applied.

[0035] If the substrate is leveled before the first reinforcing steel sheet is applied, a flat surface can be temporarily obtained. However, the high temperature and high pressure process when the first and second reinforcing steel sheets are applied will reintroduce thermal and mechanical stress, causing the leveling effect to be lost. In addition, the accumulation of stress loading and release may lead to a more complex deformation state.

[0036] In this embodiment, the pre-lamination leveling is eliminated, allowing the RFPC substrate to remain in its original or incoming material state. Reinforcing steel sheets are then sequentially laminated, ensuring that the stress history generated during all lamination processes is uniformly preserved. Finally, a single leveling operation eliminates all deformation. This method simplifies the process flow, avoids unnecessary repeated stress loading, makes the leveling operation more targeted, results in higher stability of the final board surface flatness, and optimizes production cycle time and cost.

[0037] In an optional embodiment of this application, both the first reinforcing steel sheet and the second reinforcing steel sheet are stainless steel reinforcing sheets, and are attached to the RFPC substrate by a thermosetting adhesive layer. Under the hard pressing process, the thermosetting adhesive layer is cured by heat.

[0038] Stainless steel is selected as the reinforcing material, providing stable rigid reinforcement. Even with a thickness as small as 0.12mm, it still has good mechanical support capabilities, and is corrosion-resistant and compatible with subsequent leveling pressure. A thermosetting adhesive layer, such as an epoxy resin film, is placed between the stainless steel reinforcing sheet and the RFPC substrate. This adhesive undergoes a curing reaction at a hard pressing temperature of 160-180℃, forming a high-strength adhesive interface.

[0039] like Figure 5 As shown, during the process of first applying the thin sheet and then the thick sheet, the cured adhesive layer provides immediate structural stability to the thin sheet area, offering a robust support platform for the thick sheet application. This material system and curing mechanism ensure a strong and reliable bond between the reinforcing steel sheet and the substrate throughout the application and leveling process, preventing slippage or detachment. This provides a solid technological foundation for differential thickness application and subsequent leveling deformation correction.

[0040] In an optional embodiment of this application, the RFPC substrate is an RFPC board for a camera module, and the first mounting area is a Holder area; wherein, by controlling the pressure, temperature and time of the leveling process, the flatness of the first mounting area after leveling is ≤45μm.

[0041] The Holder area in a camera module has extremely high requirements for flatness, as even minor surface undulations can directly affect the concentricity of lens assembly and image quality. In this application scenario, the first mounting area, i.e., the Holder area, is typically the head region, which uses a thinner 0.12mm reinforcing steel sheet; the tail region is reinforced with a steel sheet no less than 0.25mm thick.

[0042] By employing the aforementioned method of first attaching a thin sheet and then a thick sheet, and by selectively choosing appropriate pressure, temperature, and holding time during the final leveling process—for example, maintaining a pressure of 5-15 kg / cm² and 80-120°C for an appropriate time—the flatness of the Holder area can be stably controlled within 45 μm. This solution enables the RFPC board used in camera modules to achieve differentiated reinforcement while ensuring that the flatness of key areas fully meets the tolerance requirements for precision module assembly. This significantly reduces the risk of focusing problems or assembly interference caused by Holder area warping, thereby improving product assembly yield.

[0043] In an optional embodiment of this application, the bonding of the first reinforcing steel sheet and the second reinforcing steel sheet is performed in the following order: first, the first reinforcing steel sheet is placed in the first mounting area of ​​the RFPC substrate and hard bonding is performed; after the bonding of the first reinforcing steel sheet is completed, the second reinforcing steel sheet is placed in the second mounting area and hard bonding is performed; between the two bonding steps, the RFPC substrate is not leveled or subjected to other stress relief treatment.

[0044] This sequence clearly defines the connection between placement and pressing operations. After accurately placing the first reinforcing steel sheet in the first mounting area, hard pressing is performed immediately, and then it is removed; subsequently, the second reinforcing steel sheet is placed in the second mounting area and hard pressing is performed.

[0045] Between the two bonding steps, no leveling or deliberate stress relief treatment, such as baking to relieve stress or thermal shock, is performed. This allows the internal stress fields generated by bonding thin and thick steel sheets to be continuously superimposed and preserved, forming uniform deformation characteristics that are easily identified and corrected in the final leveling step. This method avoids the reset of deformation state that may be caused by intermediate stress relief, making the overall process window easier to control and ultimately enhancing the consistency of flatness.

[0046] In an optional embodiment of this application, the leveling process specifically involves placing the RFPC substrate with the first reinforcing steel sheet and the second reinforcing steel sheet attached in a leveling fixture, applying pressure under heating conditions and holding it for 5-30 seconds.

[0047] like Figure 6As shown, using a dedicated leveling fixture ensures uniform in-plane pressure on the board. The RFPC substrate with reinforcing steel sheets is placed in the fixture, heated to a preset temperature, and then the mold is closed and pressure is applied, maintaining the pressure for 5-30 seconds. This brief pressure holding time allows the substrate resin to undergo stress relaxation and micro-creep under warm conditions, thereby eliminating residual warping and making the board surface flatter. Simultaneously, the short pressure holding time avoids substrate aging or adhesive layer deterioration that may occur with prolonged heating. This method is convenient to operate, fast-paced, and suitable for mass production, enabling efficient leveling in a short time and consistently ensuring board flatness.

[0048] In an optional embodiment of this application, after the second reinforcing steel sheet is applied, the RFPC substrate is first cooled and then leveled.

[0049] Immediately after the second reinforcing steel sheet is applied, the RFPC substrate and the reinforcing steel sheet are still at a relatively high temperature. If leveling is performed at this time, the flat surface under thermal expansion may undergo secondary micro-deformation during subsequent cooling and contraction, affecting the stability of the final flatness. By first cooling the substrate after application, such as through natural cooling or air cooling to near room temperature, the adhesive layer and substrate can fully shrink and reach a dimensionally stable state before controlled leveling is performed.

[0050] The pressure and temperature applied during leveling, acting on a dimensionally stable board, can more accurately eliminate residual deformation. The post-cooling leveling process effectively eliminates the interference of thermal history on the final flatness, ensuring that the finished RFPC board maintains excellent flatness throughout delivery and subsequent assembly.

[0051] By applying reinforcing steel sheets with a thickness difference greater than 0.1 mm on the same substrate in a segmented and stepwise manner, starting with the thinnest and progressing to the thickest, and using differentiated hard-pressing parameters, eliminating pre-leveling while retaining final controlled leveling, and introducing material curing mechanisms and cooling processes, the stress abrupt changes and uneven warping caused by thickness differences were systematically suppressed throughout the entire process. Ultimately, while meeting the differentiated reinforcement requirements of different areas, the RFPC board achieved high flatness and good consistency, making it particularly suitable for precision electronic components such as camera modules that have stringent flatness requirements. This significantly reduced the appearance and assembly defects caused by warping, improving production yield and product reliability.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the flatness of reinforcing steel sheets pressed onto an RFPC board, used for pressing different reinforcing steel sheets with a thickness difference greater than 0.1 mm onto the same RFPC board, characterized in that... Includes the following steps: An RFPC substrate is provided, the substrate having a first mounting area and a second mounting area; In the first mounting area, a first reinforcing steel sheet of a first thickness is pressed onto the mounting area using a hard pressing process; In the second mounting area, a second reinforcing steel sheet with a second thickness is pressed by a hard pressing process. The second thickness is greater than the first thickness, and the difference between the first thickness and the second thickness is greater than 0.1 mm. The pressing step of the first reinforcing steel sheet is performed before the pressing step of the second reinforcing steel sheet; After the first and second reinforcing steel sheets are attached, the RFPC substrate and the reinforcing steel sheets thereon are leveled together.

2. The method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to claim 1, characterized in that, The first mounting area is the head area of ​​the RFPC board, and the second mounting area is the tail area of ​​the RFPC board. The first thickness is 0.12 mm, and the second thickness is not less than 0.25 mm.

3. The method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to claim 1, characterized in that, The hard pressing process of applying the first reinforcing steel sheet and the second reinforcing steel sheet is carried out under heating and pressurization conditions. The pressure when applying the first reinforcing steel sheet is 10-20 kg / cm² and the temperature is 160-180℃. The pressure when applying the second reinforcing steel sheet is 15-25 kg / cm², and the temperature is 160-180℃.

4. The method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to claim 1, characterized in that, The leveling process is either roller leveling or flat mold leveling, with a leveling temperature ranging from room temperature to 150°C and a leveling pressure of 5-15 kg / cm².

5. A method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to any one of claims 1 to 4, characterized in that, The RFPC substrate is not leveled before the first reinforcing steel sheet is applied. The leveling process only occurs after all reinforcing steel sheets have been applied.

6. The method for controlling the flatness of the reinforcing steel sheet of an RFPC board according to claim 1, characterized in that, Both the first and second reinforcing steel sheets are stainless steel reinforcing sheets, and are attached to the RFPC substrate by a thermosetting adhesive layer. Under the hard pressing process, the thermosetting adhesive layer is cured by heat.

7. The method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to claim 2, characterized in that, The RFPC substrate is an RFPC board for camera modules, and the first mounting area is a Holder area; wherein, by controlling the pressure, temperature and time of the leveling process, the flatness of the first mounting area after leveling is ≤45μm.

8. The method for controlling the flatness of the reinforcing steel sheet of an RFPC board according to claim 1, characterized in that, The first reinforcing steel sheet and the second reinforcing steel sheet are pressed together in the following order: First, place the first reinforcing steel sheet in the first mounting area of ​​the RFPC substrate and perform hard pressing; After the first reinforcing steel sheet is applied, the second reinforcing steel sheet is placed in the second mounting area and hard pressing is performed. No leveling or other stress-relieving treatment is performed on the RFPC substrate between the two bonding steps.

9. The method for controlling the flatness of RFPC board reinforcing steel sheet pressing according to claim 1, characterized in that, The leveling process specifically involves placing the RFPC substrate with the first and second reinforcing steel sheets attached in a leveling fixture, applying pressure under heating conditions, and holding it for 5-30 seconds.

10. The method for controlling the flatness of the reinforcing steel sheet pressing of an RFPC board according to claim 1, characterized in that, After the second reinforcing steel sheet is attached, the RFPC substrate is first cooled before the leveling process is performed.

Images