Reinforcing plate, method for manufacturing the reinforcing plate, and flexible-rigid printed circuit board

Abstract

This application relates to the technical field of printed circuit boards, and particularly to a method for manufacturing a reinforcing plate, a reinforcing plate, and a rigid-flex printed circuit board. The method for manufacturing the reinforcing plate includes: providing an aluminum plate unit having opposite first and second surfaces, with placing grooves provided on both the first and second surfaces, and the two placing grooves facing away from each other; placing two BT resin substrates in the two placing grooves respectively, and providing a thermosetting adhesive between the BT resin substrates and the bottom of the placing grooves, with the shape of the BT resin substrates adapted to the shape of the placing grooves; pressing the aluminum plate unit and the two BT resin substrates together; and curing the thermosetting adhesive. The method for manufacturing the reinforcing plate of this application can better meet the requirements of rigid-flex printed circuit boards for high-frequency and high-speed performance.

Description

Technical Field

[0001] This application relates to the technical field of printed circuit boards, and particularly to a method for manufacturing a reinforcing plate, a reinforcing plate, and a rigid-flex printed circuit board. Background Art

[0002] In a rigid-flex printed circuit board, in order to provide rigidity and fixed support for it, a method of attaching a reinforcing plate to one side of the flexible board is mostly adopted. With the rapid development of 5G technology in recent years, the demand for high-frequency and high-speed performance of rigid-flex printed circuit boards in design is also increasing. The traditional manufacturing solutions for rigid-flex printed circuit boards basically only improve the flexible board to enhance high-frequency and high-speed performance. This method is difficult to meet the requirements of rigid-flex printed circuit boards for high-frequency and high-speed performance. Summary of the Invention

[0003] This application provides a method for manufacturing a reinforcing plate, a reinforcing plate, and a rigid-flex printed circuit board to better meet the requirements of rigid-flex printed circuit boards for high-frequency and high-speed performance.

[0004] An embodiment of the first aspect of this application provides a method for manufacturing a reinforcing plate, including:

[0005] Providing an aluminum plate unit, the aluminum plate unit having opposite first and second surfaces, and placing grooves are provided on both the first surface and the second surface, and the two placing grooves are arranged back to back;

[0006] Placing two BT resin substrates in the two placing grooves respectively, and providing a thermosetting adhesive between the BT resin substrate and the bottom of the placing groove, and the shape of the BT resin substrate is adapted to the shape of the placing groove;

[0007] Pressing the aluminum plate unit and the two BT resin substrates together;

[0008] Performing a curing treatment on the thermosetting adhesive.

[0009] In some embodiments, before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further includes:

[0010] Processing the placing grooves on the first surface and the second surface respectively.

[0011] In some embodiments, processing the placing grooves on the first surface and the second surface respectively specifically includes:

[0012] Providing a master plate, the master plate having a plurality of connected aluminum plate units;

[0013] Processing the placing grooves on the first surfaces of all the aluminum plate units;

[0014] Machine out the placement grooves on the second surfaces of all the aluminum plate units;

[0015] Separate a plurality of the aluminum plate units.

[0016] In some embodiments, one side edge of the first surface has a first chamfer portion, and one side edge of the second surface has a second chamfer portion opposite to the first chamfer portion.

[0017] In some embodiments, before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further includes:

[0018] Provide a mother board, and a plurality of connected aluminum plate units are arranged on the mother board;

[0019] Machine out a plurality of relief grooves on the mother board, the relief grooves are arranged in one-to-one correspondence with the aluminum plate units, the relief grooves penetrate through the mother board, and the two ends of each relief groove respectively have a first groove edge and a second groove edge;

[0020] Perform chamfering on the first groove edges of all the relief grooves so that the first chamfer portions are formed on the first groove edges;

[0021] Perform chamfering on the second groove edges of all the relief grooves so that the second chamfer portions are formed on the second groove edges;

[0022] Separate a plurality of the aluminum plate units.

[0023] In some embodiments, before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further includes: performing anodic oxidation treatment on the aluminum plate unit.

[0024] An embodiment of the second aspect of the present application provides a reinforcing plate, including:

[0025] An aluminum plate unit, the aluminum plate unit has two opposite first surfaces and a second surface, placement grooves are arranged on both the first surface and the second surface, and the two placement grooves are arranged back to back;

[0026] Two BT resin substrates, the two BT resin substrates are respectively placed in the two placement grooves, a thermosetting adhesive is arranged between the BT resin substrate and the bottom of the placement groove, and the shape of the BT resin substrate is adapted to the shape of the placement groove.

[0027] In some embodiments, a cooperation portion is arranged on one side wall of the placement groove, a clamping portion is arranged at one end of the BT resin substrate, and the cooperation portion is connected with the clamping portion in a matching manner.

[0028] In some of these embodiments, one side of the first surface has a first chamfer portion, and one side of the second surface has a second chamfer portion opposite to the first chamfer portion.

[0029] An embodiment of the third aspect of the present application provides a rigid-flex printed circuit board, and the rigid-flex printed circuit board includes a reinforcing plate as described in the second aspect.

[0030] The beneficial effect of the method for manufacturing a reinforcing plate provided by the embodiments of the present application lies in that: since placement grooves are provided on both the first surface and the second surface of the aluminum plate unit, and a BT resin substrate is provided in the placement groove, the aluminum plate unit and the BT resin substrate are press-fitted and fixed together by a thermosetting adhesive. Therefore, when the reinforcing plate is embedded into the rigid-flex printed circuit board, the BT resin substrate can be made to correspond to the signal transmission dense area on the rigid-flex printed circuit board. Thus, not only can the excellent heat resistance, excellent low dielectric performance, low thermal expansion rate, and good mechanical characteristics of the BT resin substrate and other properties be utilized to reduce the transmission loss of high-speed signals, avoid problems such as signal transmission stuttering and loss caused by the gold fingers heating up due to long-term power-on, improve the signal transmission performance of the signal transmission dense area on the rigid-flex printed circuit board, so as to better meet the requirements of the rigid-flex printed circuit board for high-frequency and high-speed performance, but also it can provide better rigidity and fixed support for the rigid-flex printed circuit board.

[0031] The beneficial effects of the reinforcing plate provided by the present application compared with the prior art and the beneficial effects of the rigid-flex printed circuit board provided by the present application compared with the prior art are both the same as the beneficial effects of the present application compared with the prior art, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 is a schematic structural diagram of a method for manufacturing a reinforcing plate in one of the embodiments of the present application;

[0034] Figure 2 is a schematic structural diagram of a reinforcing plate in one of the embodiments of the present application;

[0035] Figure 3 is Figure 2 a schematic structural diagram of the BT resin substrate in the reinforcing plate shown;

[0036] Figure 4 is a Figure 2 schematic structural diagram of a rigid-flex printed circuit board containing the reinforcing plate shown;

[0037] Figure 5 is a schematic structural view of the mother board of the aluminum plate unit in the reinforcing plate shown in Figure 2 ;

[0038] Figure 6 is Figure 2 a schematic structural view of the first chamfered portion and the second chamfered portion of the reinforcing plate shown in

[0039] The meanings of the marks in the figure are as follows:

[0040] 10. Aluminum plate unit; 11. First surface; 111. First chamfered portion; 12. Second surface; 121. Second chamfered portion; 13. Placing groove; 131. Fitting portion; 20. BT resin substrate; 21. Engaging portion; 30. Mother board; 40. Avoidance groove; 50. Flexible board; 51. Signal transmission dense area. Specific embodiments

[0041] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0043] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0044] Reference to "an embodiment", "some embodiments" or "embodiments" in the description of the present application means that a specific feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in an embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" and the like appearing in different places in this specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless otherwise specifically emphasized in another way. In addition, in one or more embodiments, specific features, structures or characteristics may be combined in any suitable manner.

[0045] To illustrate the technical solution of the present application, specific drawings and embodiments will be used for illustration below.

[0046] Please refer to Figure 1 、 Figure 2 and Figure 4 , an embodiment of the first aspect of the present application provides a method for manufacturing a reinforcing plate, including:

[0047] S100: Provide an aluminum plate unit 10. The aluminum plate unit 10 has opposite first surface 11 and second surface 12. Placing grooves 13 are provided on both the first surface 11 and the second surface 12, and the two placing grooves 13 are arranged back to back.

[0048] Specifically, the material of the aluminum plate unit 10 is aluminum. For example, 7075T6 specification aluminum with high hardness and high strength can be selected to prevent the aluminum plate unit 10 from deforming. The aluminum plate unit 10 may have already undergone a drilling process, that is, peripheral holes, part number holes, and other positioning holes have been drilled on the aluminum plate unit 10.

[0049] S200: Place two BT resin substrates 20 in the two placing grooves 13 respectively, and set thermosetting glue between the BT resin substrate 20 and the bottom of the placing groove 13. The shape of the BT resin substrate 20 is adapted to the shape of the placing groove 13.

[0050] Specifically, a BT board with a copper thickness of 1 / 3OZ can be selected to minimize the material cost. After cutting, the copper foils on both sides of the BT board are etched first to obtain the BT resin substrate 20, and then the BT resin substrate 20 is subjected to a drilling process, that is, the peripheral holes on the board edge and the anti - reverse holes for forming the routing board are drilled. The aperture of the peripheral holes can be designed to be 3.0mm for pin positioning when false - sticking with thermosetting glue.

[0051] Optionally, two sheets of thermosetting glue with a thickness of 0.025mm can be false - stuck to each BT resin substrate 20. When false - sticking, use pin nails to align with the peripheral holes of the BT resin substrate 20 for positioning, and use a vacuum false - sticking machine for false - sticking.

[0052] Optionally, after false - sticking the thermosetting glue, the BT resin substrate 20 is subjected to secondary drilling. There are two sets of drilling data for the front and back. Since the anti - reverse holes have been drilled during the first drilling, the situation of using the wrong data in production can be avoided. During the secondary drilling, the forming routing board positioning holes with a depth of 1.45mm inside the BT resin substrate 20 are drilled. These positioning holes need to be designed in the waste area of the final product to avoid depressions after pressing with the flexible - rigid printed circuit board.

[0053] Optionally, the BT resin substrate 20 is cleaned of dust to facilitate better bonding of the BT resin substrate 20 with the thermosetting glue in the later stage.

[0054] Optionally, the external dimensions of the placement groove 13 are at least 0.1 mm larger than the overall external dimensions of the BT resin substrate 20, so as to facilitate placing the BT resin substrate 20 into the placement groove 13.

[0055] Optionally, the depth of the placement groove 13 is 0.35 mm - 0.45 mm, such as 0.35 mm, 0.37 mm, 0.39 mm, 0.41 mm, 0.43 mm, and 0.45 mm, etc., and the sum of the thicknesses of the BT resin substrate 20 and the thermosetting adhesive is 0.36 mm - 0.44 mm, such as 0.36 mm, 0.38 mm, 0.40 mm, 0.42 mm, and 0.44 mm, etc. In this way, the overall flatness of the aluminum plate unit 10 and the BT resin substrate 20 can be improved, and finally the flatness of the finished flexible-rigid printed circuit board after laminating the reinforcing plate and the flexible board 50 can be improved.

[0056] S300: Laminating the aluminum plate unit 10 and two BT resin substrates 20 together.

[0057] Specifically, the aluminum plate unit 10 and two BT resin substrates 20 are placed into a fast press for rapid lamination. The fast lamination stacking method is: 2.0 mm silicone pad + silicone-free release film + aluminum plate unit 10 and two BT resin substrates 20 + silicone-free release film + 2.0 silicone pad. Among them, using a 2.0 mm silicone pad can fully fill the height difference between the BT resin substrate 20 and the aluminum plate unit 10 due to the depth control tolerance, ensuring that the BT resin substrate 20 can completely fit onto the aluminum plate unit 10, thereby improving the bonding rate between the two and further improving the product reliability. Using a silicone-free release film can avoid the precipitation of silicone oil substances due to high temperature during the fast press process, resulting in the residual silicone oil substances on the surface of the aluminum plate unit 10 after the fast press, and finally affecting the lamination reliability of the reinforcing plate and the flexible-rigid printed circuit board.

[0058] S400: Curing the thermosetting adhesive.

[0059] Specifically, the laminated aluminum plate unit 10 and two BT resin substrates 20 can be cured by baking at 150° for 2 hours to completely cure the thermosetting adhesive.

[0060] In the method for manufacturing a reinforcing plate provided by the embodiment of the present application, since placement grooves 13 are provided on both the opposite first surface 11 and the second surface 12 of the aluminum plate unit 10, and a BT resin substrate 20 is provided in the placement grooves 13, and the aluminum plate unit 10 and the BT resin substrate 20 are fixed together by hot melt adhesive pressing, when the reinforcing plate is embedded into the rigid-flex printed circuit board, the BT resin substrate 20 can be made to correspond to the signal transmission dense area 51 on the rigid-flex printed circuit board, such as corresponding to the gold finger area on the rigid-flex printed circuit board. Thus, on one hand, the excellent heat resistance, low dielectric constant, low thermal expansion rate, and good mechanical properties of the BT resin substrate 20 can be utilized to reduce the transmission loss of high-speed signals, avoid problems such as signal transmission jamming and loss caused by the gold finger heating due to long-term power-on, and improve the signal transmission performance of the signal transmission dense area 51 on the rigid-flex printed circuit board, so as to better meet the requirements of the rigid-flex printed circuit board for high-frequency and high-speed performance. On the other hand, it can also provide better rigidity and fixed support for the rigid-flex printed circuit board.

[0061] Please refer to Figure 4 , in some embodiments, before providing an aluminum plate unit 10, the method for manufacturing the reinforcing plate further includes: processing the placement grooves 13 on the first surface 11 and the second surface 12 respectively. For example, a controlled milling machine can be used to process the placement grooves 13 on the first surface 11 and the second surface 12 respectively.

[0062] Please refer to Figure 2 , Figure 3 and Figure 5 , in some embodiments, in order to improve production efficiency, processing the placement grooves 13 on the first surface 11 and the second surface 12 respectively specifically includes:

[0063] First, provide a master board 30, and the master board 30 has a plurality of connected aluminum plate units 10.

[0064] Specifically, the master board 30 has an opposite front surface and back surface. The front surface is in the same plane as the first surface 11 of all the aluminum plate units 10, and the back surface is in the same plane as the second surface 12 of all the aluminum plate units 10. In this embodiment, the size of the master board 30 is 500mm * 600mm, and peripheral holes, part number holes, and post-process milling board positioning holes are drilled on the master board 30.

[0065] Second, process the placement grooves 13 on the first surface 11 of all the aluminum plate units 10.

[0066] Specifically, a medium-viscosity protective film can be first pasted on the back surface of the master board 30 for vacuum adsorption on the controlled depth milling machine. The protective film needs to cover all the hole positions on the surface of the master board 30 to avoid vacuum leakage during vacuum adsorption. Then, use the controlled depth milling machine to process the placement grooves 13 on the first surface 11 of all the aluminum plate units 10, and tear off the protective film on the back surface after processing.

[0067] Next, the placement grooves 13 on the second side 12 of all the aluminum plate units 10 are processed.

[0068] Specifically, a medium-viscosity protective film can be first pasted on the front surface of the mother board 30 for vacuum adsorption on the depth-controlled milling machine. The protective film needs to cover all the hole positions on the surface of the mother board 30 to avoid vacuum leakage during vacuum adsorption. Then, the depth-controlled milling machine is used to process the placement grooves 13 on the second side 12 of all the aluminum plate units 10. After processing, the protective film on the front surface is torn off.

[0069] Finally, the multiple aluminum plate units 10 are separated.

[0070] Specifically, the mother board 30 can be separated into multiple individual aluminum plate units 10 by stamping.

[0071] Optionally, after separating the multiple aluminum plate units 10, the multiple individual aluminum plate units 10 can be washed under high pressure to wash away the residual aluminum powder and aluminum chips on the aluminum plate units 10 and clean the plate surface.

[0072] By adopting the above scheme, the placement grooves 13 on the first side 11 and the second side 12 of the multiple aluminum plate units 10 can be processed with only two processes, with high processing efficiency and reduced production costs.

[0073] Please refer to Figure 2 、 Figure 4 and Figure 6 , in some of the embodiments, in order to prevent the right-angle edge of the reinforcing plate from causing the circuit across the right-angle edge on the rigid-flex board to break during the subsequent lamination of the reinforcing plate and the rigid-flex board, resulting in batch scrapping abnormalities, one side edge of the first side 11 has a first chamfer portion 111, and one side edge of the second side 12 has a second chamfer portion 121 opposite to the first chamfer portion 111. Both the first chamfer portion 111 and the second chamfer portion 121 can be in the form of an inclined chamfer or a rounded corner. In this way, it can be avoided that the edges and corners of the first side and the second side directly contact the circuit on the rigid-flex board, resulting in its breakage.

[0074] It can be understood that multiple first chamfer portions 111 and multiple second chamfer portions 121 can both be provided.

[0075] In this embodiment, both the first chamfer portion 111 and the second chamfer portion 121 are in the form of an inclined chamfer. The angle α of the inclined chamfer is 18° - 22°, such as 18°, 20°, and 22°, etc., and the width D is 0.8 mm - 1.0 mm, such as 0.8 mm, 0.9 mm, and 1.0 mm, etc. The inclined chamfer can be processed using a diamond 70° bevel tool. In this way, it can be further avoided that the edges and corners of the first side and the second side directly contact the circuit on the rigid-flex board, resulting in its breakage.

[0076] Please refer to Figure 2 、 Figure 3 and Figure 5 , in some embodiments, before providing an aluminum plate unit 10, the method for manufacturing the reinforcing plate further includes:

[0077] First, provide a mother board 30, on which there are a plurality of connected aluminum plate units 10.

[0078] Specifically, the mother board 30 has opposite front and back surfaces. The front surface is in the same plane as the first surfaces 11 of all the aluminum plate units 10, and the back surface is in the same plane as the second surfaces 12 of all the aluminum plate units 10.

[0079] Secondly, process a plurality of avoidance grooves 40 on the mother board 30. The avoidance grooves 40 are arranged in one-to-one correspondence with the aluminum plate units 10. The avoidance grooves 40 penetrate the mother board 30, and the two ends of the avoidance grooves 40 respectively have a first groove edge and a second groove edge.

[0080] Specifically, the avoidance grooves 40 penetrate the front and back surfaces of the mother board 30. Both the first groove edge and the second groove edge are right-angled edges. The first groove edge and the second groove surface are respectively located on the front surface and the back surface of the mother board 30. When pressing with the flexible-rigid printed circuit board subsequently, the first groove edge and the second groove edge will cause the circuit across the first groove edge and the second groove edge on the flexible-rigid printed circuit board to break, resulting in batch scrapping anomalies.

[0081] Then, chamfer the first groove edges of all the avoidance grooves 40 so that a first chamfered portion 111 is formed on the first groove edges.

[0082] Specifically, a medium-viscosity protective film can be pasted on the back surface of the mother board 30 first for vacuum adsorption on the controlled-depth router. The protective film needs to cover all the hole positions on the surface of the mother board 30 to avoid vacuum leakage during vacuum adsorption. Then, use a diamond bevel tool to chamfer the first groove edges of all the avoidance grooves 40 to form the first chamfered portion 111.

[0083] Next, chamfer the second groove edges of all the avoidance grooves 40 so that a second chamfered portion 121 is formed on the second groove edges.

[0084] Specifically, a medium-viscosity protective film can be pasted on the front surface of the mother board 30 first for vacuum adsorption on the controlled-depth router. The protective film needs to cover all the hole positions on the surface of the mother board 30 to avoid vacuum leakage during vacuum adsorption. Then, use a diamond bevel tool to chamfer the second groove edges of all the avoidance grooves 40 to form the second chamfered portion 121.

[0085] Finally, separate the plurality of aluminum plate units 10.

[0086] Specifically, the mother board 30 can be separated into a plurality of individual aluminum plate units 10 by stamping.

[0087] Through the above technical solution, the processing efficiency of the first chamfered portion 111 and the second chamfered portion 121 can be improved.

[0088] Optionally, when chamfering the first groove edge of all the relief grooves 40, the placement grooves 13 on the first surface 11 of all the aluminum plate units 10 can be processed simultaneously; when chamfering the second groove edge of all the relief grooves 40, the placement grooves 13 on the second surface 12 of all the aluminum plate units 10 can be processed simultaneously.

[0089] In some embodiments, before providing an aluminum plate unit 10, the method for manufacturing the reinforcing plate further includes: performing an anodic oxidation treatment on the aluminum plate unit 10. In this way, the surface hardness of the aluminum plate unit 10 can be further improved and the surface of the plate can be prevented from being scratched.

[0090] Optionally, the mother board 30 can be subjected to anodic oxidation treatment.

[0091] In this embodiment, the aluminum plate unit 10 is subjected to black anodic oxidation treatment.

[0092] Please refer to Figures 1 to 6 , the embodiments of the first aspect of the present application provide a method for manufacturing a reinforcing plate, including:

[0093] I. Sub-process

[0094] 1. Processing flow of the BT resin substrate 20: blanking → inner layer etching → first drilling → temporarily attaching thermosetting adhesive

[0095] → second drilling → forming and routing the board → pre-laminating.

[0096] Among them, for blanking: since the width of the conventional Sony D3451 thermosetting adhesive is fixed at 250 mm, in order to ensure the production efficiency during temporarily attaching the thermosetting adhesive and facilitate mass production, the blanking size of the BT board is designed to be 250 * 300 mm, which can ensure the maximum utilization rate while taking into account the production efficiency.

[0097] Among them, for inner layer etching: the BT board itself is a double-sided copper clad board. When purchasing, a BT board with a copper thickness of 1 / 3 OZ is selected to minimize the material cost. After blanking, the copper foils on both sides are etched away to obtain the BT resin substrate 20.

[0098] Among them, for the first drilling: only the peripheral holes on the board edge and the anti-reverse holes for forming and routing the board are drilled during the first drilling. There are two drilling data for the front and the back. The peripheral holes are designed to be 3.0 mm and are used for pin positioning when temporarily attaching the thermosetting adhesive.

[0099] Among them, the false pasting of thermosetting glue: For each BT resin substrate 20, 2 pieces of Sony D3451 thermosetting glue with a thickness of 0.025 mm are falsely pasted. When falsely pasting, use pin nails to align with the peripheral holes of the BT resin substrate 20 and then position them, and use a vacuum false pasting machine for false pasting.

[0100] Among them, the secondary drilling: During the secondary drilling, there are two drilling data for the front and back. Since the anti-reverse holes have been drilled during the first drilling, it can avoid the situation of using the wrong data for production. During the secondary drilling, the forming routing positioning holes with a depth of 1.45 mm inside the board are drilled. These positioning holes need to be designed in the waste area of the final product to avoid depressions after pressing with the flexible-rigid board.

[0101] Among them, the forming routing: When designing the outer shape of the forming routing, add a bump design without affecting the outer shape of the final product, which can improve the production efficiency when embedding the aluminum plate unit 10 and play a role in horizontal anti-fooling, that is, prevent the positioning holes of the routing from being placed in the wrong direction.

[0102] Among them, the pre-lamination: Before embedding the aluminum plate unit 10 after forming, it is necessary to clean the dust on the BT resin substrate 20.

[0103] 2. Thermosetting glue process: Blanking → First drilling → False pasting of BT board.

[0104] Among them, the blanking: The width of the conventional Sony D3451 thermosetting glue is fixed at 250 mm. For the false pasting production with the BT resin substrate 20, the blanking size of the thermosetting glue is designed as 250 * 300 mm, which can ensure the maximum utilization rate while taking into account the production efficiency.

[0105] Among them, the first drilling: Only drill the peripheral holes on the board edge and the anti-reverse holes during the forming routing. There are two drilling data for the front and back (it can also be understood that two pieces of thermosetting glue are attached to both sides of the BT resin substrate 20, so the drilling data for the front and back are different). The peripheral holes are designed as 3.0 mm for the pin positioning when falsely pasting with the BT resin substrate 20.

[0106] Among them, the false pasting of the BT resin substrate 20: For every 2 pieces of Sony D3451 thermosetting glue, one BT resin substrate 20 is falsely pasted. When falsely pasting, use pin nails to align with the peripheral holes of the BT resin substrate 20 and then position them, and use a vacuum false pasting machine for false pasting.

[0107] 3. Aluminum plate process: Blanking → Black anodizing → First drilling → First routing → Back side film pasting → Front side depth control and bevel → First film tearing → Front side film pasting → Back side depth control and bevel → Second film tearing → High-pressure water washing → Pre-lamination.

[0108] Among them, the blanking: To ensure that the board surface does not deform and the stability of the depth control during the double-sided depth control production of the large board of the mother board 30, the material of the mother board 30 uses 7075T6 specification aluminum with higher hardness and strength, and the size is designed as 500 * 600 mm.

[0109] Among them, black anodizing: The color of anodizing is not limited. Anodizing can further improve the surface hardness of the mother board 30 and prevent the board surface from being scratched.

[0110] Among them, primary drilling: Drill out the peripheral holes, part number holes, and positioning holes for the subsequent routing process on the board.

[0111] Among them, primary routing: Use an ordinary router to route out multiple relief slots 40 in advance. The two ends of the relief slot 40 each have a first slot edge and a second slot edge. Compared with routing out multiple relief slots 40 on a depth-controlled router, it has higher efficiency and can avoid the complicated process of pasting multiple layers of film.

[0112] Among them, reverse film pasting: Before front depth control, a medium-viscosity protective film needs to be pasted on the reverse side of the mother board 30 for vacuum adsorption on the depth-controlled router. The protective film needs to cover all the holes on the board surface to avoid vacuum leakage during vacuum adsorption.

[0113] Among them, front depth control and beveling: According to the engineering design data, depth control is performed in a specific area of the aluminum plate, and the placement grooves 13 on the first side 11 of all the aluminum plate units 10 are processed. The depth requirement of the placement groove 13 is 0.35 mm - 0.45 mm. The size of the placement groove 13 is 0.1 mm larger than the overall forming size of the BT resin substrate 20. The placement groove 13 is designed with a recess to correspond to the bump on the BT resin substrate 20; Chamfering is performed on the first slot edge of all the relief slots 40 so that a first chamfered portion 111 is formed on the first slot edge. The first chamfered portion 111 is in the shape of an inverted bevel, and the angle α of the inverted bevel is 18° - 22°, and the width is 0.8 mm - 1.0 mm. It is produced using a diamond 70° bevel tool.

[0114] Among them, primary film tearing: After the front depth control and beveling are completed, the protective film on the reverse side of the mother board 30 is torn off.

[0115] Among them, front film pasting: After the front depth control is completed and before the reverse depth control, a medium-viscosity protective film needs to be pasted on the front side of the mother board 30 for vacuum adsorption on the depth-controlled router. The protective film needs to cover all the holes on the board surface to avoid vacuum leakage during vacuum adsorption.

[0116] Among them, reverse depth control and beveling: The design method and engineering data are made with reference to the method of front depth control and beveling.

[0117] Among them, secondary film tearing: After the reverse depth control and beveling are completed, the protective film on the front side of the mother board 30 is torn off. Thus, the production of the placement grooves 13, the first chamfered portion 111, and the second chamfered portion 121 on both sides is completed.

[0118] Among them, high-pressure water washing: High-pressure water washing is used to wash away the residual aluminum powder and aluminum chips on the mother board 30 after depth control and beveling, and clean the board surface.

[0119] II. Main Process

[0120] Embed the BT resin substrate 20 → Rapid lamination → Curing and baking → Molding and routing.

[0121] Among them, for the BT resin substrate 20: First, tear off the release film of the thermosetting adhesive on the BT resin substrate 20, align the bumps on the BT resin substrate 20 with the grooves on the aluminum plate unit 10, and perform the embedding operation. The BT resin substrate 20 is embedded in the placement grooves 13 on both the first side 11 and the second side 12 of the aluminum plate unit 10.

[0122] Among them, for rapid lamination: Put the aluminum plate unit 10 with the BT resin substrate 20 embedded on both sides into a fast laminator for rapid lamination. The fast lamination stacking method is: 2.0mm silicone pad + silicone-free release film + embedded aluminum plate + silicone-free release film + 2.0 silicone pad. Among them, using a 2.0mm silicone pad can fully fill the height difference between the BT resin substrate 20 and the aluminum plate unit 10 due to the depth control tolerance, ensuring that the BT resin substrate 20 can fully adhere to the aluminum plate unit 10, thereby improving the bonding rate between the two and further improving the product reliability. Using a silicone-free release film can avoid the precipitation of silicone oil substances due to high temperature during the fast lamination process, resulting in the residual silicone oil substances on the surface of the aluminum plate unit 10 after fast lamination, ultimately affecting the lamination reliability of the reinforcing plate and the flexible-rigid printed circuit board.

[0123] Among them, for curing and baking: After rapid lamination, it is necessary to perform curing and baking at 150° + 2H to completely cure the thermosetting adhesive.

[0124] Among them, for molding: Perform molding production according to the engineering design data.

[0125] Please refer to Figure 2 and Figure 4 , the embodiment of the second aspect of the present application provides a reinforcing plate, including an aluminum plate unit 10 and two BT resin substrates 20.

[0126] The aluminum plate unit 10 has two opposite first sides 11 and second sides 12. Placement grooves 13 are provided on both the first side 11 and the second side 12, and the two placement grooves 13 are arranged back to back.

[0127] The two BT resin substrates 20 are respectively placed in the two placement grooves 13. A thermosetting adhesive is provided between the BT resin substrate 20 and the bottom of the placement groove 13, and the shape of the BT resin substrate 20 is adapted to the shape of the placement groove 13.

[0128] The reinforcing plate provided by the embodiment of the present application has placing grooves 13 provided on both the relatively first surface 11 and the second surface 12 of the aluminum plate unit 10. A BT resin substrate 20 is provided in the placing groove 13, and the aluminum plate unit 10 and the BT resin substrate 20 are press-fitted and fixed together by a thermosetting adhesive. Therefore, when the reinforcing plate is embedded into the rigid-flex printed circuit board, the BT resin substrate 20 can be made to correspond to the signal transmission dense area 51 on the rigid-flex printed circuit board. Thus, the excellent heat resistance, low dielectric constant, low thermal expansion rate, and good mechanical properties of the BT resin substrate 20 can be utilized to reduce the transmission loss of high-speed signals, avoid problems such as signal transmission jamming and loss caused by the gold finger heating up due to long-term power-on, thereby improving the signal transmission performance of the signal transmission dense area 51 on the rigid-flex printed circuit board to better meet the requirements of the rigid-flex printed circuit board for high-frequency and high-speed performance, and can also provide better rigidity and fixed support for the rigid-flex printed circuit board.

[0129] Please refer to Figure 2 、 Figure 3 and Figure 4 In some embodiments, a mating portion 131 is provided on one side wall of the placing groove 13, and a engaging portion 21 is provided at one end of the BT resin substrate 20. The mating portion 131 and the engaging portion 21 are engaged and connected.

[0130] By adopting the above solution, when the two BT resin substrates 20 are respectively placed in the two placing grooves 13, the mating portion 131 and the engaging portion 21 can be engaged and connected to prevent the BT resin substrate 20 from being placed in the wrong direction.

[0131] Optionally, the mating portion 131 is provided as a protrusion, and the engaging portion 21 is provided as a groove adapted to the protrusion; or, the mating portion 131 is provided as a groove, and the engaging portion 21 is provided as a protrusion adapted to the groove.

[0132] In this embodiment, the mating portion 131 is provided as a groove, and the engaging portion 21 is provided as a protrusion adapted to the groove.

[0133] Please refer to Figure 2 、 Figure 3 and Figure 4 An embodiment of the third aspect of the present application provides a rigid-flex printed circuit board, which includes the reinforcing plate as in the second aspect.

[0134] It can be understood that the rigid-flex printed circuit board further includes two flexible printed circuit boards 50. The reinforcing plate is disposed between the two flexible printed circuit boards 50. Signal transmission dense areas 51 are provided on both of the two flexible printed circuit boards 50. The two BT resin substrates 20 on the reinforcing plate respectively correspond to the signal transmission dense areas 51 on the two flexible printed circuit boards 50.

[0135] In the flexible-rigid printed circuit board provided by the embodiment of the present application, since the reinforcing plate is disposed between two flexible printed boards 50, in the signal transmission dense area 51 on the flexible printed board 50, the BT resin substrate 20 on the reinforcing plate corresponds to the signal transmission dense area 51 on the flexible printed board 50, and placement grooves 13 are provided on both the first surface 11 and the second surface 12 of the aluminum plate unit 10 of the reinforcing plate that face each other, the BT resin substrate 20 is disposed in the placement grooves 13, and the aluminum plate unit 10 and the BT resin substrate 20 are press-fitted and fixed together by a thermosetting adhesive. Therefore, on one hand, the excellent heat resistance, low dielectric constant, low thermal expansion rate, and good mechanical properties of the BT resin substrate 20 can be utilized to reduce the transmission loss of high-speed signals, avoid problems such as signal transmission jamming and loss caused by long-term power-on heating of the gold fingers, and improve the signal transmission performance of the signal transmission dense area 51 on the flexible-rigid printed circuit board, so as to better meet the requirements of the flexible-rigid printed circuit board for high-frequency and high-speed performance. On the other hand, it can also provide better rigidity and fixed support for the flexible-rigid printed circuit board.

[0136] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for manufacturing a reinforcing plate, characterized in that, Comprising: Providing an aluminum plate unit, the aluminum plate unit having opposite first and second surfaces, placing grooves being provided on both the first surface and the second surface, and the two placing grooves being arranged back to back; Placing two BT resin substrates respectively in the two placing grooves, and providing a thermosetting adhesive between the BT resin substrate and the bottom of the placing groove, the shape of the BT resin substrate being adapted to the shape of the placing groove, and the two BT resin substrates being arranged back to back; Pressing the aluminum plate unit and the two BT resin substrates together; Performing a curing treatment on the thermosetting adhesive to obtain a reinforcing plate, the reinforcing plate being used for embedding into a rigid-flexible printed circuit board, and the BT resin substrate corresponding to a signal transmission dense area on the rigid-flexible printed circuit board.

2. The method for manufacturing the reinforcement plate according to claim 1, characterized in that, Before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further comprises: Processing the placing grooves respectively on the first surface and the second surface.

3. The method for manufacturing a reinforcing plate according to claim 2, wherein Processing the placing grooves respectively on the first surface and the second surface, specifically comprising: Providing a master plate having a plurality of connected aluminum plate units; Processing the placing grooves on the first surfaces of all the aluminum plate units; Processing the placing grooves on the second surfaces of all the aluminum plate units; Separating the plurality of aluminum plate units.

4. The method for manufacturing a reinforcing plate according to claim 1, wherein, One side edge of the first surface has a first chamfered portion, and one side edge of the second surface has a second chamfered portion opposite to the first chamfered portion.

5. The method for manufacturing a reinforcing plate according to claim 4, wherein, Before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further comprises: Providing a master plate having a plurality of connected aluminum plate units; Processing a plurality of relief grooves on the master plate, the relief grooves being arranged in one-to-one correspondence with the aluminum plate units, the relief grooves penetrating through the master plate, and the two ends of the relief grooves respectively having a first groove edge and a second groove edge; Performing chamfering on the first groove edges of all the relief grooves so that the first chamfered portion is formed on the first groove edges; Performing chamfering on the second groove edges of all the relief grooves so that the second chamfered portion is formed on the second groove edges; Separating the plurality of aluminum plate units.

6. The method for manufacturing a reinforcing plate according to any one of claims 1 to 5, characterized in that, Before providing an aluminum plate unit, the method for manufacturing the reinforcing plate further comprises: performing an anodic oxidation treatment on the aluminum plate unit.

7. A reinforcing plate, characterized in that, Comprising: An aluminum plate unit having opposite first and second surfaces, placing grooves being provided on both the first surface and the second surface, and the two placing grooves being arranged back to back; Two BT resin substrates, the two BT resin substrates being respectively placed in the two placing grooves, a thermosetting adhesive being provided between the BT resin substrate and the bottom of the placing groove, the shape of the BT resin substrate being adapted to the shape of the placing groove, and the two BT resin substrates being arranged back to back; The reinforcing plate is used for embedding into a rigid-flexible printed circuit board, and the BT resin substrate corresponds to a signal transmission dense area on the rigid-flexible printed circuit board.

8. The reinforcing plate according to claim 7, wherein A mating portion is provided on one side wall of the placing groove, and a engaging portion is provided at one end of the BT resin substrate, and the mating portion is in mating connection with the engaging portion.

9. The reinforcing plate according to claim 7, wherein, One side of the first surface has a first chamfered portion, and one side of the second surface has a second chamfered portion opposite to the first chamfered portion.

10. A rigid-flex printed circuit board, characterized in that, The rigid-flex printed circuit board includes the reinforcing plate according to any one of claims 7 to 9.

Images