Manufacturing method of wire harness-like rigid-flex printed circuit board with large length-width ratio

Abstract

The invention discloses a manufacturing method of a wire-harness-like rigid-flex board with a large length-width ratio. The manufacturing method comprises the following steps: manufacturing a copper pattern board with a connecting copper pattern which stretches across a bending area and extends into an ineffective area; corresponding to the connection copper pattern, a connection position windowing pattern is manufactured by extending from the edge of the bending region to the ineffective region, but does not exceed the part of the connection copper pattern penetrating into the ineffective region; a double-sided flexible copper-clad plate is taken, a micro-groove is milled in the area, corresponding to the connecting copper pattern, of the edge of a bending area, then the double-sided flexible copper-clad plate is arranged between the two copper pattern plates in a laminated mode and pressed, and the connecting copper pattern faces the outside of the plates; then milling a through groove in the edge of the bending area to form a middle core plate, stacking and pressing the plate layers, then uncovering and etching the bending area, and finally forming; the overall processing forms a technological process with a complete processing logic process on the basis of a pattern distribution design and a size relation design, a front-back matching processing effect is formed, and the processing quality of the rigid-flex printed circuit board is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of flexible board manufacturing, and in particular to a method for manufacturing a wire harness-type rigid-flexible board with a large aspect ratio. Background Art

[0002] With the development of intelligent connected vehicles and low-altitude aircraft, there is a trend of using flexible circuit boards to replace wiring harnesses in the design and application of rigid-flex boards, i.e., wire harness-like rigid-flex boards, in which the flexible area generally has a larger aspect ratio to meet the needs of longer wiring harness connections.

[0003] During the processing of the harness-type large aspect ratio rigid-flexible board, it is necessary to lay a covering film on the surface of the flexible circuit board. If the length and width of the covering film are relatively large, the several harness-type covering films formed are prone to scattering and difficulty in alignment during the processing. Furthermore, if the shape of the covering film is not made in advance and the shape is made when the whole board is formed, it is easy to cause milling pulling and tearing problems due to the long milling path of the flexible board. If laser cutting is used, it is easy to cause the problem of difficulty in removing carbon black from the finished board after forming, resulting in a short circuit.

[0004] Therefore, in order to solve the above-mentioned problems, it is necessary to provide a method for manufacturing a wire harness-type rigid-flexible board with a large aspect ratio. Summary of the invention

[0005] The present invention aims to solve the problems of the prior art of the wire harness-type rigid-flexible board with a large aspect ratio, such as easy scattering and difficulty in alignment and bonding during processing when the covering film has a large aspect ratio, and proposes a method for manufacturing a wire harness-type rigid-flexible board with a large aspect ratio. The rigid-flexible board is designed with a forming line, the area within the forming line is an effective area, and the remaining area is an invalid area. The effective area includes a bending area and a rigid area. The manufacturing method comprises the following steps: S10: taking a first covering film, a copper layer being attached to the surface of the first covering film, making a first covering film window pattern on the first covering film corresponding to the rigid area, and then making a first circuit pattern on the copper layer to form a copper pattern board as a whole; making the first circuit pattern includes making a connecting copper pattern in the bending area, the connecting copper pattern spanning the bending area and extending into the invalid area, and the part extending into the invalid area is the extending length; making a connecting position window pattern corresponding to the connecting copper pattern, the connecting position window pattern extending from the edge of the bending area to the invalid area; the width of the connecting position window pattern is greater than or equal to the width of the connecting copper pattern, and the length of the connecting position window pattern is less than the extending length; S20: Take the double-sided flexible copper-clad board again, make a second circuit pattern, form a core board pattern, mill and cut micro grooves at the edge of the bending area and in the area corresponding to the connecting copper pattern to form a micro groove board; then place the micro groove board between the two copper pattern boards for lamination and pressing, with the connecting copper pattern facing away from the micro groove board; then mill and cut through grooves at the edge of the bending area to form an intermediate core board; S30: taking two layers of prepregs, and attaching a reverse cover film to one side of the area corresponding to the bending area, to form a first prepreg layer and a second prepreg layer respectively; S40: manufacturing a first rigid core board and a second rigid core board, stacking the first rigid core board, the first semi-cured layer, the intermediate core board, the second semi-cured layer and the second rigid core board in order from top to bottom to form a stacked structure, and then pressing them together to form a pressed board; the reverse covering film faces the intermediate core board; S50: performing a cover-lifting process on the bending area of ​​the pressed plate to expose the connecting copper pattern, thereby forming a cover-lifted rigid-flex plate; S60: etching the uncovered rigid-flex board, and then molding the rigid area to form the rigid-flex board.

[0006] Furthermore, the copper graphic board is produced by punching the first covering film to produce the first covering film window pattern, wherein the first covering film window pattern includes the connection position window pattern, to form a window covering film, taking the copper layer to attach a micro-adhesive film layer to the first surface, pressing the second surface with the window covering film, removing the micro-adhesive film layer, producing the first circuit pattern, and forming the copper graphic board.

[0007] Furthermore, the connection position window pattern is manufactured by laser ablating the first covering film of the connection position window pattern.

[0008] Furthermore, manufacturing the copper pattern plate includes manufacturing a first grid copper pattern in the region of the invalid area.

[0009] Furthermore, manufacturing the intermediate core board includes manufacturing a second grid copper pattern in the region of the ineffective area.

[0010] Furthermore, the side of the reverse covering film adjacent to the rigid area is retracted corresponding to the bending area, and the other sides extend into the ineffective area.

[0011] Furthermore, the cover removal process is to perform controlled-depth milling on the bending area of ​​the pressed plate, and the depth of the controlled-depth milling is from the plate surface to the reverse covering film.

[0012] Furthermore, the length of the connection position window pattern is shorter than the extension length of the connection copper pattern by 25 μm to 105 μm.

[0013] Furthermore, the milling micro-grooves are cut by laser milling.

[0014] Furthermore, the milling width of the micro groove is 5 μm to 25 μm.

[0015] The technical solution of the present invention forms a connected overall structure of the bending area covering film and the invalid area covering film through the connection position pattern, effectively avoiding the problems of several wire harness-type covering films in the prior art being easily scattered and difficult to align and fit during processing; by making a corresponding connection position window pattern on the covering film, and laser cutting a through groove on the edge of the bending area, the bending area is pre-formed, that is, there is only a connection with the connection position pattern at the edge of the bending area, and there is no connection with the covering film, and then the size relationship between the reverse-sticking covering film and the bending area in the press plate is used to control the depth of milling to expose the connection position copper pattern, which is removed through etching and then the rigid area is formed, effectively preventing milling pulling and tearing problems, and also effectively avoiding the problems of short circuit caused by the difficulty in removing the carbon black produced by laser cutting the bending area; the overall processing forms a process flow with a complete processing logic process based on the pattern distribution design and the size relationship design, forming a front-to-back matching processing effect, and effectively improving the processing quality of the rigid-flexible board. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 is a process flow chart; Figure 2 It is a schematic diagram of the cross-sectional structure of a copper graphic board; Figure 3 for Figure 2 A schematic diagram of the front structure of Figure 4 for Figure 2 Schematic diagram of the reverse structure; Figure 5 Schematic diagram of the plane structure of the micro-grooved plate; Figure 6 is a schematic diagram of the cross-sectional structure of the laminated structure; Figure 7 It is a structural schematic diagram of the front side of the middle core plate; Figure 8 It is a schematic diagram of the cross-sectional structure of the stacked structure; Fig. 9 is a schematic diagram of the cross-sectional structure of a pressed plate; Fig.10 It is a schematic diagram of the planar structure of the rigid-flex board; Fig.11 for Fig.10 AA cross-sectional structure schematic diagram; Fig.12 It is a schematic diagram of the cross-sectional structure of the rigid-flexible board.

[0018] Description of Figure Numbers: The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] See also Figure 1 , Figure 1 It is a process flow chart.

[0024] The manufacturing process of the embodiment of the present invention includes using Figure 1 The following will implement the various steps in the process Figure 1Each step in the process is further explained step by step.

[0025] See also Figure 2 , Figure 3 and Figure 4 , Figure 2 It is a schematic diagram of the cross-sectional structure of a copper graphic board; Figure 3 for Figure 2 A schematic diagram of the front structure of Figure 4 for Figure 2 Schematic diagram of the reverse structure.

[0026] The rigid-flex board 90 of this embodiment is designed with a molding line 100 , and the area within the molding line 100 is an effective area 100A, including a bending area 1010A and a rigid area 1020A, and the remaining area is an ineffective area 100B.

[0027] Step S10: Take a first covering film with a copper layer attached to its surface, make a first covering film window pattern 1040 on the first covering film corresponding to the rigid area 1020A, and then make a first circuit pattern on the copper layer to form a copper pattern board 10 as a whole.

[0028] The key to this embodiment is to make a first circuit pattern, including making a connecting copper pattern 1010 in 1010A, the connecting copper pattern 1010 spans the bending area 1010A and extends into the invalid area 100B, and the part extending into the invalid area 100B forms an extending length 1050, so that the covering film of the bending area 1010A and the covering film of the invalid area 100B form a connected overall structure through the connecting copper pattern 1010, which effectively avoids the problems of several wire harness-type covering films formed in the prior art being easily scattered during the processing and difficult to align and fit.

[0029] Since the temperature required for the milling process of the connecting copper pattern 1010 is much higher than that of the milling process of the covering film, after the pressing process, the area of ​​the first covering film corresponding to the connecting copper pattern 1010 is blocked, making it difficult to perform the milling process. Therefore, in this process, a connecting position window pattern 1030 needs to be made corresponding to the connecting copper pattern 1010 to expose the connecting copper pattern 1010 in this area, forming a pre-milling process, and the connecting position window pattern 1030 extends from the edge of the bending area 1010A to the invalid area 100B.

[0030] Furthermore, the width of the connection position window pattern 1030 is greater than or equal to the width of the connection copper pattern 1010, and the length of the connection position window pattern 1030 is less than the extension length, thereby partially exposing the connection position window pattern 1030. By widening the width of the connection position window pattern 1030, the laser milling of the covering film adjacent to the connection copper pattern 1010 is reduced, which effectively avoids the situation in which a part of the heat is conducted to the internal covering film through the connection copper pattern 1010 during laser groove milling in the subsequent process. When the internal covering film is heated, deformation, melting, and carbon powder generation may occur.

[0031] In one embodiment, the copper graphic board is manufactured by punching the first covering film to manufacture a first covering film window pattern 1040, wherein the first covering film window pattern includes a connecting position window pattern 1030 to form a window covering film. The first covering film window pattern 1040 is manufactured by punching, which produces less waste than laser cutting and has the advantages of high speed and low cost, thereby helping to improve processing efficiency. Then, the copper layer is attached to the first surface with a micro-adhesive film layer, the second surface is pressed with the window covering film, the micro-adhesive film layer is removed, a first circuit pattern is manufactured, and a copper graphic board 10 is formed. The micro-adhesive film layer is pre-attached to one side and then the other side is pressed with the covering film after punching, so that the micro-adhesive film layer plays a role of temporary fixation and provides support, so that the covering film can be stably attached to the surface of the copper layer, so that the subsequent removal operation will not cause problems such as position displacement.

[0032] In one embodiment, the connection position window pattern 1030 is produced by laser ablation of the first covering film of the connection position window pattern 1030. Laser ablation can provide higher processing accuracy and reduce mechanical stress on the material, thereby avoiding pulling deformation or damage to the material caused by mechanical punching.

[0033] Furthermore, the length of the connecting window pattern 1030 is less than the extension length 1050 of the connecting copper pattern 1010 by 25 μm to 105 μm, thereby ensuring the stability of the connecting copper pattern 1010 connecting the covering film of the bending area 1010A with the covering film of the invalid area 100B to form a continuous structure, and effectively avoiding problems such as falling off and misalignment of the connecting copper pattern 1010 after pressing in the subsequent process due to excessive window opening.

[0034] In one embodiment, manufacturing the copper pattern board 10 includes manufacturing a first grid copper pattern 1020 in the invalid area 100B, which, on the one hand, plays an anti-slip role in laminating a large-area covering film and improves the bonding strength between the laminating layers; on the other hand, since copper has good thermal conductivity, it has the beneficial effect of helping to maintain the overall operating temperature of the circuit board during the processing.

[0035] See also Figure 5 picture, Figure 6 and Figure 7 , Figure 5 Schematic diagram of the plane structure of the micro-grooved plate; Figure 6 is a schematic diagram of the cross-sectional structure of the laminated structure; Figure 7 This is a schematic structural diagram of the front side of the middle core plate.

[0036] Step S20: Then take a double-sided flexible copper clad laminate, make a second circuit pattern, form a core board pattern 1040, mill micro grooves 2020 at the edge of the bending area and in the area corresponding to the connection copper pattern 1010, to form a pre-milling for the bending area 1010A, which provides a processing basis for the subsequent forming process without the need to form the bending area 1010A, and the micro groove board 20 is formed as a whole.

[0037] The micro-groove plate 20 is then arranged between the two copper graphic plates 10 for stacking to form a stacked structure 30, and then pressed together, with the connecting copper graphic 1010 facing away from the micro-groove plate 20, and then the edge of the bending area 1010A is milled with a through groove 4010 to form an intermediate core plate 40; the connecting copper graphic 1010 is formed on the outer surface of the intermediate core plate 40, which provides a processing basis for the subsequent process of uncovering the connecting copper graphic 1010, and then laser milling is performed to connect it with the connecting position window graphic 1030 made in the previous process to form a through groove 4010, so that the bending area 1010A is formed as a whole. When the whole board is formed in the subsequent process, the bending area 1010A is avoided from being formed and milled, and the flexible board milling in the bending area 1010A is effectively prevented from pulling, tearing and other problems caused by milling.

[0038] Furthermore, manufacturing the intermediate core board 40 includes manufacturing a second mesh copper pattern 2030 in the invalid area 100B. Similar to the first mesh copper pattern 1020 , the second mesh copper pattern 2030 can also play a good role in heat dissipation and anti-slip, which will not be described in detail.

[0039] In this embodiment, since the microgroove 2020 is located at the edge of the bending zone 1010A, the milling of the microgroove 2020 is carried out by laser milling, which can accurately control the cutting path, effectively avoid the removal of excess material due to inaccurate positioning, and effectively improve the processing accuracy; the milling width of the microgroove is 5μm to 25μm, and the width of the laser milling ablation microgroove is not easy to be too wide, otherwise it is easy to cause the problem of pressing depression.

[0040] See also Figure 8 , Figure 8 Schematic diagram of the cross-section structure of the stacked structure.

[0041] Step S30: Take two layers of semi-cured sheets, and attach a reverse covering film to one side of the area corresponding to the bending area to form a first semi-cured layer 50A and a second semi-cured layer 50B respectively, which are used to participate in the stacking and pressing processing in the subsequent process and play the role of the bonding layer.

[0042] In this embodiment, the edges of the reverse covering film 5010 adjacent to the rigid area 100B are retracted inwardly in the corresponding bending area 1010A, and the other edges extend into the invalid area 100B. By retracting inwardly in the bending area 1010A, the reverse covering film 5010 is effectively prevented from extending into the rigid area 100B. After lamination in the subsequent process, the reverse covering film 5010 is pressed and fixed, which increases the difficulty of removing the reverse covering film 5010. The other edges penetrate into the invalid area 100B to form a covering and protective effect on the connecting copper pattern 1010, thereby preventing the connecting copper pattern 1010 from forming a bonding effect with the first semi-cured layer 50A and the second semi-cured layer 50B during the lamination process, which is not conducive to the subsequent uncovering process.

[0043] Please refer again Figure 8 , and see Fig. 9 , Fig. 9 Schematic diagram of the cross-sectional structure of the pressed plate.

[0044] Step S40: A first rigid core board 60A and a second rigid core board 60B are manufactured, and the first rigid core board 60A, the first semi-cured layer 50A, the middle core board 40, the second semi-cured layer 50B and the second rigid core board 60B are stacked in sequence from top to bottom to form a stacked structure 200, and then pressed together to form a pressed board 70, with the reverse covering film 5010 facing the middle core board 40; since the depth of the subsequent uncovering process is from the board surface to the reverse covering film 5010, on the one hand, the inertia and peelability of the reverse covering film 5010 are utilized to provide a processing basis for the subsequent uncovering process, and on the other hand, a protective effect is formed on the board surface, reducing the debris that may be generated during the uncovering process to contaminate the board surface, which is beneficial to the etching process in the subsequent process.

[0045] See also Fig.10 and Fig.11 , Fig.10 It is a schematic diagram of the planar structure of the rigid-flex board; Fig.11 for Fig.10 Schematic diagram of the AA cross-section structure.

[0046] Step S50: The bending area 1010A of the pressing plate 70 is uncovered to expose the connecting copper pattern 1010, thereby providing a processing basis for subsequent etching steps, and forming a uncovered rigid-flex board 80 as a whole.

[0047] In one embodiment, the cover removal process is to perform controlled-depth milling on the bending area 1010A of the pressed plate 70 , and the depth of the controlled-depth milling is from the plate surface to the reverse covering film 5010 .

[0048] See also Fig.12 , Fig.12 It is a schematic diagram of the cross-sectional structure of the rigid-flexible board.

[0049] Step S60: The uncovered rigid-flex board 80 is etched, and then the rigid area 100B is molded to form a rigid-flex board 90 .

[0050] Since the connecting copper pattern 1010 is responsible for connecting the covering film with the effective area 100A and the bending area 1010A and assisting in positioning the covering film, the connecting copper pattern 1010 is etched away in this process after being exposed through the uncovering process, and a laser through groove 4010 is formed at the edge of the bending area 1010A in the previous process, that is, the bending area 1010A has been formed, so only the rigid area 1010B needs to be formed to form a rigid-flexible composite board 90 as a whole.

[0051] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio, characterized in that: The rigid-flexible board is designed with a forming line, the area within the forming line is an effective area, and the remaining area is an invalid area, the effective area includes a bending area and a rigid area, and the manufacturing method includes the following steps: S10: taking a first covering film, wherein a copper layer is attached to the surface of the first covering film, making a first covering film window pattern on the first covering film corresponding to the rigid area, and then making a first circuit pattern on the copper layer to form a copper pattern board as a whole; Making the first circuit pattern includes making a connecting copper pattern in the bending area, wherein the connecting copper pattern spans the bending area and extends into the invalid area, and the portion extending into the invalid area is the extending length; A connection position window pattern is formed corresponding to the connection copper pattern, and the connection position window pattern extends from the edge of the bending area to the invalid area; The width of the connection position window pattern is greater than or equal to the width of the connection copper pattern, and the length of the connection position window pattern is less than the insertion length; S20: taking a double-sided flexible copper-clad laminate, making a second circuit pattern, forming a core board pattern, and milling microgrooves at the edge of the bending area and in the area corresponding to the connecting copper pattern to form a microgroove board; Then, the micro-grooved plate is arranged between the two copper pattern plates for lamination and pressing, with the connecting copper pattern facing away from the micro-grooved plate; Then, a through groove is cut by milling at the edge of the bending area to form an intermediate core plate; S30: taking two layers of prepregs, and attaching a reverse cover film to one side of the area corresponding to the bending area, to form a first prepreg layer and a second prepreg layer respectively; S40: manufacturing a first rigid core board and a second rigid core board, stacking the first rigid core board, the first semi-cured layer, the intermediate core board, the second semi-cured layer and the second rigid core board in order from top to bottom to form a stacked structure, and then pressing them together to form a pressed board; The reverse covering film faces the middle core plate; S50: performing a cover-lifting process on the bending area of ​​the pressed plate to expose the connecting copper pattern, thereby forming a cover-lifted rigid-flex plate; S60: etching the uncovered rigid-flex board, and then molding the rigid area to form the rigid-flex board.

2. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The copper graphic board is produced by punching the first covering film to produce the first covering film window pattern, wherein the first covering film window pattern includes the connection position window pattern, forming a window covering film, taking the copper layer and attaching a micro-adhesive film layer to the first surface, pressing the second surface and the window covering film, removing the micro-adhesive film layer, producing the first circuit pattern, and forming the copper graphic board.

3. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The connection position window pattern is produced by laser ablating the first covering film of the connection position window pattern.

4. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The manufacturing of the copper pattern plate includes manufacturing a first grid copper pattern in the region of the invalid area.

5. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The manufacturing of the intermediate core board includes manufacturing a second grid copper pattern in the region of the ineffective area.

6. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The side of the reverse cover film adjacent to the rigid area is retracted inwardly corresponding to the bending area, and the other sides extend into the ineffective area.

7. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The cover-lifting process is to perform controlled-depth milling on the bending area of ​​the pressed plate, and the depth of the controlled-depth milling is from the plate surface to the reverse covering film.

8. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The distance by which the length of the connection position window pattern is smaller than the extension length of the connection copper pattern is 25 μm to 105 μm.

9. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 1, characterized in that: The milling micro grooves are cut by laser milling.

10. The method for manufacturing a wire harness-type rigid-flex board with a large aspect ratio as claimed in claim 9, characterized in that: The milling width of the micro groove is 5 μm to 25 μm.

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