Manufacturing method of semi-flexural rigid-flexual combined board with large bending angle

Abstract

The application discloses a manufacturing method of a semi-flexural rigid-flexible combined plate with a large bending angle, takes double-sided copper-clad plates, manufactures a core plate pattern, and forms an intermediate core plate; takes a copper layer which is divided into an upper surface copper layer and a lower surface copper layer, takes a first prepreg and a second prepreg, and is stacked with the intermediate core plate to form a stacking structure, and then is pressed to form a pressed plate; a surface circuit pattern is manufactured on the pressed plate, a depth-controlled milling cut is performed on a bending area to form a groove, the groove is milled to form a trapezoid, and then is formed; the positioning mold is manufactured and is fixed by using a pin to ensure the stability of the plate during the manufacturing process, so that the overall structural stability of the finished product is improved; the positioning mold is used for guidance, and a micro-current loop process is formed in the overall milling process, so that the milling precision is effectively improved, and the processing of the high-precision circuit board is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rigid-flex printed circuit board manufacturing, in particular to a method for manufacturing a semi-flex rigid-flex printed circuit board with large bending angle. BACKGROUND

[0002] The semi-flex rigid-flex printed circuit board is a kind of multi-layer circuit board combining rigid board and flexible board together, which has the characteristics of sequential bending or less times of bending, and plays an important role in some intelligent networked vehicle power modules or industrial control modules applications due to its high integration, high space utilization and other advantages.

[0003] However, for the semi-flex rigid-flex printed circuit board with a thickness greater than the width of the bending area, it is often difficult to form an effective bending with a large angle (such as 90 degrees).

[0004] The processing method for the above-mentioned rigid-flex printed circuit board with thick thickness is generally as follows: when designing the laminated circuit board, different window sizes are made on different layers, and after pressing, a step structure is formed at the step position of the rigid board area and the bending area; or a cover is opened from the board surface to the bottom of the bending area in sequence and multiple times to form a bending area with a step structure.

[0005] However, the above two processing methods have certain defects: if the processing method of opening window first and then pressing is used, step deformation, glue overflow and other problems are likely to occur at the folding step position; if the processing method of multiple cover opening is used, the vibration, friction, expansion and contraction generated during the processing process are too large, which is likely to cause, and the process is relatively complex and the processing cost is relatively high.

[0006] Therefore, in order to solve the above-mentioned problems, a method for manufacturing a semi-flex rigid-flex printed circuit board with large bending angle is needed. SUMMARY

[0007] The present application aims to solve the problem that the semi-flex rigid-flex printed circuit board of the prior art cannot realize large-angle effective bending when the thickness of the board is greater than the width of the bending area, and proposes a method for manufacturing a semi-flex rigid-flex printed circuit board with large bending angle, which includes a bending area and a rigid area, the width of the bending area is less than or equal to the thickness of the rigid-flex printed circuit board, and the manufacturing method includes the following steps:

[0008] S10: Take a double-sided copper-clad plate, make a core plate pattern, and form an intermediate core plate;

[0009] S20: Take a copper layer, the copper layer is divided into an upper surface copper layer and a lower surface copper layer, and take a first prepreg and a second prepreg, stack them with the intermediate core plate to form a stacking structure, and then press them to form a pressed plate; the stacking structure is stacked from top to bottom as follows: the upper surface copper layer, the second prepreg, the intermediate core plate, the first prepreg and the lower surface copper layer.

[0010] S30: manufacturing a surface circuit pattern on the pressboard, and controlling deep milling on the bending area to form a groove, and forming a groove plate;

[0011] S40: milling the groove to form a trapezoidal groove, and then reshaping to form a half-flexural rigid-flexible combined plate with a large bending angle.

[0012] Further, the manufacturing method comprises: attaching a first cover film to the area of the first prepreg corresponding to the bending area, and the first cover film in the stacking structure is arranged towards the intermediate core plate.

[0013] Further, a third prepreg is taken to manufacture a blind groove to form a blind groove prepreg, and the blind groove is located at the edge of the bending area; the stacking structure comprises: the blind groove prepreg is arranged between the intermediate core plate and the first prepreg; and the blind groove is arranged towards the first prepreg.

[0014] Further, the blind groove prepreg is attached with a second cover film corresponding to the bending area.

[0015] Further, the first cover film is greater than or equal to the bending area on one side.

[0016] Further, the deep controlled milling is milling to the first cover film.

[0017] Further, the second cover film is less than or equal to the bending area on one side.

[0018] Further, the milling comprises: manufacturing a positioning mold, the positioning mold has a bearing end and a fixed end, the bearing end is a two-surface structure connected to each other, and the intersection line of the two surfaces is a top edge; fixing the groove plate on the positioning mold, the bending area corresponds to the top edge, the groove faces away from the top edge, and the rigid area is fixed on the two surfaces respectively, and the bending surface forms an acute angle; forming a to-be-milled structure; fixing the to-be-milled structure on the table surface of a milling machine, the groove plate is away from the table surface, and the rigid plate forms an acute angle with a milling cutter used for milling; and then performing the milling processing.

[0019] Further, the manufacturing of the groove plate further comprises: drilling through holes and electroplating processing on the pressboard, the through holes form positioning through holes, then the surface circuit pattern is manufactured, the surface circuit pattern comprises a limiting circuit pattern, and the positioning through hole is in communication with the limiting circuit pattern.

[0020] Further, the fixing of the groove plate on the positioning mold comprises that the bearing end is provided with a first pin hole; a first pin is used to fix the groove plate on the surface of the bearing end through the first pin hole and the positioning through hole; the fixed end is provided with a second pin hole, and the table top is provided with a table top fixing hole; a second pin is used to fix the milling structure on the table top through the second pin hole and the table top fixing hole; the table top is a conductive table top, and the milling machine has a control center which is electrically connected with the conductive table top and the milling cutter.

[0021] The technical scheme of the present application ensures the position stability and processing precision of the plate in the manufacturing process by making the positioning mold and using the pin fixing as an auxiliary processing tool, thereby improving the overall structural stability of the finished product, reducing the possible quality problems in the production process, and enhancing the reliability of the product in actual application; the milling is performed by using the guiding of the mold, combining the control center with the conductive table top to form an automatic control system, and setting the whole milling process to form a micro-current loop process of “milling cutter→limiting line pattern→positioning through hole→pin→milling machine→control center→milling cutter”, thereby effectively improving the milling precision and being beneficial to the processing of high-precision circuit boards. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0023] Figure 1 The process flow diagram of the embodiment of the present application;

[0024] Figure 2 The cross-sectional view of the stacked structure of the embodiment of the present application;

[0025] Figure 3 The cross-sectional view of the pressed plate of the embodiment of the present application;

[0026] Figure 4 The cross-sectional view of the groove plate of the embodiment of the present application;

[0027] Figure 5 The planar structure schematic view of Figure 4 ;

[0028] Figure 6 The structure schematic view of the milling processing of the embodiment of the present application;

[0029] Figure 7 FIG. 1 is a schematic view of a cross-sectional structure of a rigid-flex printed circuit board according to an embodiment of the present application.

[0030] BRIEF DESCRIPTION OF DRAWINGS

[0031]

[0032] The objectives, features and advantages of the present application will be further understood from the following detailed description in conjunction with the appended drawings. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without any creative effort fall within the protection scope of the present application.

[0034] It should be noted that all the directionality indications (such as up, down, left, right, front, back, inside, outside, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings). If the specific posture is changed, the directionality indications will also be changed accordingly.

[0035] In addition, the descriptions such as “first”, “second” and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of “plurality” is at least two, such as two, three, etc., unless otherwise specifically limited.

[0036] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0037] Please refer to Figure 1 , Figure 1 FIG. 2 is a schematic view of a process flow according to an embodiment of the present application.

[0038] The manufacturing process of the embodiment of the present application includes the implementation of each step flow in Figure 1 The following will further step by step describe each step flow in Figure 1

[0039] Please refer to Figure 2 ,​Figure 2 A cross-sectional view of the laminated structure according to an embodiment of the present application.

[0040] The rigid-flex printed circuit board 10 according to the embodiment comprises a bending area 10A and a rigid area 10B, wherein the width of the bending area 10A is less than or equal to the thickness of the rigid-flex printed circuit board 10.

[0041] Step S10:

[0042] Take the double-sided copper-clad plate, make the core plate pattern 1010, and form the intermediate core plate 100, i.e., the base layer of the multi-layer laminated structure, to provide the core plate base for the subsequent processing.

[0043] Please refer to Figure 2 , and refer to Figure 3 , Figure 3 A cross-sectional view of the laminated structure according to an embodiment of the present application.

[0044] Step S20:

[0045] Take the copper layer, which is divided into an upper surface copper layer 200 and a lower surface copper layer 300, and take the first prepreg 400 and the second prepreg 500, and stack them with the intermediate core plate 100 to form a laminated structure 20, and then laminate to form a laminated plate 30; the laminated structure 20 is stacked from top to bottom as the upper surface copper layer 200, the second prepreg 500, the intermediate core plate 100, the first prepreg 400, and the lower surface copper layer 300.

[0046] In the embodiment, the manufacturing method comprises attaching a first cover film 4010 to the area of the first prepreg 400 corresponding to the bending area 10A, and the first cover film 4010 is usually made of polyimide material, which is converted from the cover film material of the flexible circuit board. On the one hand, the first cover film 4010 can provide an additional flexible layer, which helps to disperse the stress of the bending area 10A when the rigid-flex printed circuit board 10 is applied, and plays a role in buffering the stress, thereby reducing the risk of damage caused by stress concentration. On the other hand, the first cover film 4010 can increase the flexibility of the bending area 10A, so that it is easier to achieve a large-angle bending, and can maintain good performance even after multiple bendings.

[0047] Further, the first cover film 4010 in the laminated structure 20 is arranged towards the intermediate core plate 10, i.e., the structure is provided with a structure basis that is easy to uncover for the subsequent controlled depth milling processing by using the inertness between the first cover film 4010 and the base material, and at the same time, the first cover film 4010 forms a protective film for the first prepreg 400 exposed by the bending area 10A, thereby avoiding problems such as tearing and falling of the first prepreg 400, causing contamination of the plate surface, and other problems when the rigid-flex printed circuit board 10 is applied, and having the effect of prolonging the service life of the rigid-flex printed circuit board 10.

[0048] Take the third prepreg, make a blind slot 6010, form a blind slot prepreg 600, the blind slot 6010 is located at the edge of the bending area, at this time the lamination structure 20 includes, the blind slot prepreg 600 is arranged between the middle core board 100 and the first prepreg 400; the blind slot 6010 is arranged towards the first prepreg 600, forming a pre-milling cut, effectively cooperating with the depth control milling cut in the later process, that is, forming a depth control milling cut around the edge of the bending area 10A, the depth of the depth control milling cut is the board surface to the blind slot 6010, and the rigid plate in the depth control milling cut area is removed, avoiding the position of the depth control milling cut depth to the first cover film 4010, effectively reducing the risk of damage to the first prepreg 400 by milling, providing a larger milling error tolerance, improving the processing precision of the circuit board, and also effectively avoiding excessive vibration and expansion caused by a large amount of depth control milling on the circuit board.

[0049] Further, the blind slot prepreg 600 is attached with a second cover film 6020 corresponding to the bending area 10A, and the second cover film 6020 is usually also made of polyimide material, which is also used as the cover film material of the flexible circuit board. Combined with the arrangement of the first cover film 4010 described above, a to-be-pressed structure corresponding to the first cover film 4010 is formed, and the material of the cover film has strong inertia, so that the first cover film 4010 and the second cover film 6020 form a good release effect when pressed, and effectively cooperate with the cover processing after the depth control milling in the later process.

[0050] Further, the first cover film 4010 is greater than or equal to the bending area 10A on one side, forming a structure in which the first cover film 4010 penetrates into the interior of the circuit board, that is, using the high reliability, bending property, and the advantages of not being easy to crack and chip of the first cover film 4010, to form a covering protection effect on the first prepreg 600 exposed after milling, avoiding tearing and chipping of the first prepreg 600 during bending, causing board surface pollution and other problems, and prolonging the service life of the circuit board.

[0051] Further, the second cover film 6020 is less than or equal to the bending area 10A on one side, which can effectively reduce unnecessary material use and reduce production costs, and on the other hand, avoid forming a structure in which the first cover film 4010 and the second cover film 6020 penetrate into the interior of the circuit board. In the case of large-angle bending, the first cover film 4010 and the second cover film 6020 have a certain thickness and form a release effect with each other, which may not be able to resist the bending stress, and in the application process, the rigid-flex combined board 10 may crack at the junction of the bending area 10A and the rigid area 10B.

[0052] Please refer to Figure 4 and Figure 5 , Figure 4A schematic view of a cross-sectional structure of the recessed plate according to an embodiment of the present application; Figure 5 A schematic view of a planar structure of the recessed plate according to an embodiment of the present application; Figure 4 A schematic view of a planar structure of the recessed plate according to an embodiment of the present application;

[0053] Step S30:

[0054] The surface circuit pattern 410 is made on the pressing plate 30, and the depth-controlled milling is performed on the bending area 10A, which is milled to the first cover film 4010 to form the recess 420, and the whole plate forms the recessed plate 40, which provides a plate base for the subsequent milling process.

[0055] The depth-controlled milling operation can reduce the effective thickness of the bending area 10A, so that the bending area 10A is more easily deformed without damaging the internal circuit, in addition, the depth-controlled milling is only milled to the position of the first cover film 4010, which can effectively avoid the influence on the underlying structure layer, and ensure the stability and reliability of the overall structure.

[0056] Please refer to Figure 6 and Figure 7 , Figure 6 A schematic view of a milling process structure according to an embodiment of the present application; Figure 7 A schematic view of a cross-sectional structure of the rigid-flex combined plate according to an embodiment of the present application.

[0057] Step S40:

[0058] The milling process 50 is performed on the recess 420 to form a trapezoidal shape 440, and then the forming line 700 is formed to form a semi-flex rigid-flex combined plate 10 with a large bending angle.

[0059] The milling process can reduce the material thickness during bending, so that the required bending angle can be more easily achieved, and in the present embodiment, since the width of the bending area 10A is less than or equal to the thickness of the rigid-flex combined plate 10, the most critical processing step is to further process the recess 420 into a trapezoidal shape by the milling process 50, so that the plate surface can form a larger bending angle, and the design, processing and application precision of the rigid-flex combined plate 10 is improved.

[0060] In the present embodiment, the milling process 50 needs to make a positioning mold 510 to provide an auxiliary function, the positioning mold 510 has a bearing end 5110 and a fixed end 5120, the bearing end 5110 has a two-face structure connected to each other, the intersection line of the two faces is the top edge, the recessed plate 40 is fixed on the positioning mold 510, the bending area 10A corresponds to the top edge, the recess 420 is opposite to the top edge, and the rigid area 10B is fixed on the two faces respectively, at this time, the bending surface formed by the bending area 10A forms an acute angle, that is, an angle greater than 180° and less than 360°, which is preferably 190° to 330°, or 210°, or 225°, or 270°, and the whole forms a structure to be milled.

[0061] Then the structure to be milled is fixed on the table of the milling machine 520, the groove plate 40 is away from the table, and the plate surface of the rigid area 10B is at an acute angle with the milling cutter 530 used for milling; then the milling process is performed, which not only ensures a certain distance between the groove plate 40 and the table, but also allows the rigid plate surface to be at an acute angle with the milling cutter 530, so as to ensure that the milling cutter 530 can accurately cut into the material without being disturbed by the table during the milling process, and the direction of the milling cutter 530 can be effectively controlled.

[0062] Further, the groove plate 40 also includes the following steps: drilling through holes in the pressed plate 30 and electroplating processing, the through holes form positioning through holes 430, the main function of the positioning through holes 430 is to provide electrical connection for the entire milling process 50, and also to provide a positioning reference for fixing the structure to be milled by using a pin in the subsequent process. Then the surface circuit pattern 410 is made, which not only contains the actual circuit required wiring, but also includes a specially designed limiting circuit pattern 410A. It is worth noting that the limiting circuit pattern 410A is calculated to determine the specific layout position of the limiting circuit pattern 410A, and supports the communication between the positioning through hole and the limiting circuit pattern, which provides a milling position limit for the rigid plate surface in the subsequent milling process, effectively cooperates with the current feedback control milling, and avoids excessive damage to the circuit pattern 410 during milling.

[0063] In the embodiment, fixing the groove plate 40 on the positioning mold 510 includes the following steps: the bearing end 5110 is provided with a first pin hole; the first pin 540 is used to fix the groove plate 40 on the surface of the bearing end 5110 through the first pin hole and the positioning through hole 430; the fixed end 5120 is provided with a second pin hole, and the table is provided with a table fixing hole; the second pin 550 is used to fix the milling structure on the table through the second pin hole and the table fixing hole, which ensures the stability and accuracy of the groove plate 40 during the entire processing process, and displacement is not easy to occur during the processing process.

[0064] In the embodiment, the table is a conductive table 560, and the milling machine 520 has a control center 5210, which is electrically connected with the conductive table 560 and the milling cutter 530, respectively. This allows the control center 5210 to control the entire processing process through the conductive table 560, forming a current loop of “milling cutter 530→ limiting circuit 410A→ positioning through hole 430→ first pin 540→ second pin 550→ conductive table 560→ wire 570→ control center 5210→ milling cutter 530”, realizing the process of current feedback control milling, and achieving the purpose of high-precision processing.

[0065] For the circuit board with high precision and large bending angle, the fixing and control system can better adapt to the special processing requirements, can realize more complex shape cutting without damaging the material, significantly improve the positioning accuracy in the milling process, and realize high-precision processing of the rigid-flex combined board 10, thereby increasing the stability and reliability of the rigid-flex combined board 10 in practical application. The whole process from positioning to fixing to final milling forms a semi-automatic system processing, reduces the error caused by human factors, and improves the processing precision of the circuit board.

[0066] In summary, by making the positioning mold 510 as an auxiliary processing tool, fixed on the table surface of the milling machine 520, and then fixed on the positioning mold 510 when the milling mechanism is fixed, the bending area 10A corresponds to the top edge, and the rigid area 10B is fixed on the two surfaces respectively. At this time, the bending area 10A reversely bends to form a top angle protruding state, so that the circuit board forms an effective processable state; and by using the guiding property of the positioning mold 510, the whole milling process is set to form a current loop path of "milling cutter 530→limiting line 410A→positioning through hole 430→first pin 540→second pin 550→conductive table surface 560→conductive wire 570→control center 5210→milling cutter 530", which meets the high-precision milling processing requirements, effectively improves the milling precision, and is beneficial to the processing of high-precision rigid-flex combined boards.

[0067] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made under the inventive concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for manufacturing a high-bend-angle half-folding rigid-flex printed circuit board, characterized in that, The rigid-flexible combination board comprises a bending area and a rigid area, the width of the bending area is less than or equal to the thickness of the rigid-flexible combination board, and the manufacturing method comprises the following steps: S10: taking a double-sided copper-clad plate, manufacturing a core plate pattern, and forming an intermediate core plate; S20: taking a copper layer, the copper layer being divided into an upper surface copper layer and a lower surface copper layer, and taking a first prepreg and a second prepreg, stacking the intermediate core plate to form a stacking structure, and then pressing to form a pressed plate; The stacking structure is stacked from top to bottom as follows: the upper surface copper layer, the second prepreg, the intermediate core plate, the first prepreg, and the lower surface copper layer; A third prepreg is taken, a blind groove is manufactured, and a blind groove prepreg is formed, the blind groove being located at the edge of the bending area; the blind groove prepreg is arranged between the intermediate core plate and the first prepreg; and the blind groove is arranged towards the first prepreg; S30: manufacturing a surface circuit pattern on the pressed plate, and performing depth-controlled milling on the bending area to form a groove, thereby forming a groove plate; S40: milling the groove to form a trapezoidal groove, and then forming a semi-flexible rigid-flexible combination board with a large bending angle; The milling is as follows, A positioning mold is manufactured, the positioning mold having a bearing end and a fixed end, the bearing end being in a two-surface structure connected to each other, and the intersection line of the two surfaces being a top edge; The groove plate is fixed on the positioning mold, the bending area corresponding to the top edge, the groove facing away from the top edge, and the rigid area being fixed on the two surfaces, respectively, and the bending surface formed by the bending area forming an acute angle; a to-be-milled structure is formed; The to-be-milled structure is fixed on the table surface of a milling machine, the groove plate being separated from the table surface, and the rigid plate and the milling cutter forming an acute angle; and then milling is performed.

2. A method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as described in claim 1, wherein, The manufacturing method comprises, in the region of the first prepreg corresponding to the bending area, attaching a first cover film, The first cover film in the stacking structure is arranged towards the intermediate core plate.

3. The method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as claimed in claim 1, wherein, The blind groove prepreg is attached with a second cover film corresponding to the bending area.

4. The method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as claimed in claim 2, wherein, The first cover film is greater than or equal to the bending area on one side.

5. A method of fabricating a semi-flexural rigid-flex printed circuit board with a large bending angle as claimed in claim 2 or 4, wherein, The depth-controlled milling is milling to the first cover film.

6. The method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as recited in claim 3, wherein, The second cover film is less than or equal to the bending area on one side.

7. The method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as recited in claim 1, wherein, The manufacturing of the groove plate further comprises: drilling a through hole in the pressed plate and performing electroplating processing, the through hole forming a positioning through hole, and then manufacturing the surface circuit pattern, the surface circuit pattern comprising a limiting circuit pattern, and the positioning through hole being in communication with the limiting circuit pattern.

8. The method of fabricating a high-bend-angle half-folding rigid-flex printed circuit board as claimed in claim 7, wherein, The fixing of the groove plate on the positioning mold comprises: The bearing end is provided with a first pin hole; a first pin is used to fix the groove plate on the surface of the bearing end through the first pin hole and the positioning through hole; The fixed end is provided with a second pin hole, and the table surface is provided with a table surface fixing hole; a second pin is used to fix the to-be-milled structure on the table surface through the second pin hole and the table surface fixing hole; The table surface is a conductive table surface, the milling machine has a control center, and the control center is electrically connected with the conductive table surface and the milling cutter, respectively.

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