Manufacturing method of circuit board with board edge inner socket

Abstract

The invention discloses a method for manufacturing a circuit board with board edge inner sockets, which comprises the following steps of: manufacturing surface core boards with copper-plated through holes and stepped circuit patterns on one side, manufacturing windowing prepregs, arranging release layers in windowing patterns of the windowing prepregs, forming middle core boards, arranging the middle core boards between the two layers of surface core boards in a stacking manner, and forming the circuit board with the board edge inner sockets. Pressing to form a pressed plate; sequentially manufacturing a surface circuit pattern and a dry film pattern on the laminated plate, and performing depth-controlled milling to expose the release layer and remove the release layer to form a plate edge groove plate; carrying out micro-etching on the board edge groove board, then electroplating a golden finger, and stripping the film after the whole board is formed to form a circuit board; the golden fingers are arranged on the edge of the circuit board to form the incorporated internal insertion interface, so that the space of the circuit board is effectively utilized, the problem that space crowding possibly occurs for multiple electronic modules in a small space is solved, effective cooperation is formed before and after the whole processing process, the whole processing process is simple, high-precision processing can be realized, and the production efficiency is improved. And the service life of the circuit board is prolonged.

Description

Technical Field

[0001] The invention relates to the field of circuit board manufacturing, and in particular to a method for manufacturing a circuit board with a board edge inner socket. Background Art

[0002] With the development of civil electronics or automotive electronics, the functions of related products are increasing, so the requirements for high density of the applied circuit boards are getting higher and higher.

[0003] Gold fingers are usually distributed on the surface of circuit boards to meet the needs of plugging or welding, especially by welding connectors, connecting wiring harnesses or flexible circuit boards or other circuit boards to achieve some electronic functions. However, welding connectors have certain requirements for processing conditions, and connectors will occupy a certain space. Therefore, for electronic modules that require more functions in a smaller space, space congestion will occur.

[0004] The existing technology realizes the high-density application of electronic modules by reducing the size of the circuit board on the one hand and the volume of the connecting device on the other hand, which also brings corresponding defects. On the one hand, the wiring density per unit area will increase due to the reduction in the size of the circuit board; on the other hand, the volume of the connecting device is reduced, and it becomes a high-precision device, which increases the difficulty of processing, resulting in an increase in processing costs and an increase in scrap rate.

[0005] Therefore, in order to solve the problems raised by the above background technology, it is necessary to provide a method for manufacturing a circuit board with an inner socket on the board edge. Summary of the invention

[0006] The present invention aims to solve the problem of comprehensive performance such as high-density application of electronic modules required by the circuit board in the prior art, and proposes a method for manufacturing a circuit board with an inner socket on the board edge. The area within the range of the molding line of the circuit board during the processing is the effective area, and the remaining area is the invalid area. The effective area of ​​the circuit board includes a circuit pattern area and a gold finger area, and the gold finger area corresponds to the inner socket on the board edge. The manufacturing method includes the following steps: S10: manufacturing a surface core board having copper-plated through holes and a stepped circuit pattern on one side; the stepped circuit pattern is composed of a completely etched circuit pattern in the circuit pattern area and an incompletely etched circuit pattern in the gold finger area; the copper-plated through hole is close to the area of ​​the incompletely etched circuit pattern; S20: taking a prepreg, making a window pattern, and setting a release layer in the window pattern to form an intermediate core board; the release layer corresponds to the gold finger area and extends to cover the area where the copper-plated through hole is located; S30: placing the intermediate core board between the two layers of the surface core boards to form a stacked structure, and then pressing them together to form a pressed board; the stepped circuit patterns of the two layers of the surface core boards in the stacked structure are arranged relative to each other, and the copper-plated through holes are located in the region of the release layer; S40: forming a surface circuit pattern, a dry film pattern, and controlled depth milling on the laminated board in sequence, exposing a portion of the release layer, and then removing the release layer to form a board edge groove board; the controlled depth milling is to perform milling in the area where the release layer exceeds the copper-plated through hole, and the depth of the milling is from the board surface to the surface of the release layer; S50: micro-etching the groove plate at the edge of the board, forming the incompletely etched circuit into a gold finger circuit, electroplating the gold finger, forming the whole board, and then stripping the film to form the circuit board.

[0007] Furthermore, the surface core board is manufactured by: making through holes in a double-sided copper clad laminate and electroplating to form the copper-plated through holes, then making a first dry film pattern on the first side of the double-sided copper clad laminate, performing a first etching, then making a second dry film pattern on the gold finger area of ​​the first side, performing a second etching, and then stripping the film to form a stepped circuit to form the surface core board.

[0008] Furthermore, after the first etching, the residual etching thickness of the circuit pattern in the circuit pattern area is 3 microns to 8 microns; and the second etching is to form the completely etched circuit pattern.

[0009] Furthermore, one side of the release layer is larger than the gold finger area.

[0010] Furthermore, the stepped circuit pattern extends to the invalid area.

[0011] Furthermore, the copper-plated through-hole is a micro-hole.

[0012] Furthermore, one side of the release layer is smaller than the window pattern.

[0013] Furthermore, the dry film pattern is a plating chuck position exposing the electroplating gold finger.

[0014] Furthermore, manufacturing the surface core board includes manufacturing a conductive circuit pattern on the ineffective area, wherein the conductive circuit pattern connects the electroplating clamp position and the copper-plated through hole.

[0015] Furthermore, the material of the release layer is: PI material, PTFE material or low-flow prepreg.

[0016] The technical solution of the present invention achieves effective utilization of the circuit board space by setting the gold finger at the edge of the circuit board to form a groove-type plug-in interface, thereby solving the problem of space congestion that may occur for multiple electronic modules in a small space; the stepped circuit is formed by etching in steps and zones, so that the etching accuracy of the circuit is controllable, corresponding to the semi-cured sheet and the release layer, and then the release layer is milled and removed in the post-process to form a groove with an incompletely etched circuit, and then the post-process etching and electroplating are carried out to form a finished circuit board. The whole processing process forms an effective coordination before and after, the overall processing process is simple, high-precision processing can be achieved, and the service life of the circuit board is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 Schematic diagram of the process flow of an embodiment of the present invention; Figure 2 A schematic plan view of a surface core plate according to an embodiment of the present invention; Figure 3 For the implementation of the present invention Figure 2 AA section schematic diagram of the surface core plate; Figure 4 For the implementation of the present invention Figure 2 BB cross-section diagram of the surface core plate; Figure 5 For use of the embodiments of the present invention Figure 3 Schematic diagram of the cross-sectional structure of the stacked structure formed by the AA section; Figure 6 For use of the embodiments of the present invention Figure 4 Schematic diagram of the cross-sectional structure of the laminated plate formed by the middle BB section; Figure 7 For the implementation of the present invention Figure 6 Schematic diagram of CC plane structure of the pressed plate; Figure 8 For the implementation of the present invention Figure 6 Schematic diagram of the cross-sectional structure of the plate edge groove formed by the pressed plate processing; Fig. 9 For the implementation of the present invention Figure 8 Schematic diagram of the cross-sectional structure of the gold finger board formed by processing the edge groove board; Fig.10 For the implementation of the present invention Fig. 9 Schematic diagram of the cross-sectional structure of a circuit board with an internal socket on the edge of the board formed by processing a gold finger board.

[0019] Description of Figure Numbers:

[0020] 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

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] See also Figure 1 , Figure 1 Schematic diagram of the process flow of an embodiment of the present invention.

[0026] 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 1 Each step in the process is further explained step by step.

[0027] In this embodiment, the area within the range of the forming line 10 of the circuit board during processing is the effective area 101, and the remaining area is the invalid area 102. The effective area 101 of the circuit board includes a circuit pattern area 1010 and a gold finger area 1020, and the gold finger area 1020 corresponds to the socket inside the board edge.

[0028] See also Figure 2 , Figure 3 and Figure 4 , Figure 2 A schematic plan view of a surface core plate according to an embodiment of the present invention; Figure 3 For the implementation of the present invention Figure 2 AA section schematic diagram of the surface core plate; Figure 4 For the implementation of the present invention Figure 2 Schematic diagram of the BB cross section of the surface core panel.

[0029] Step S10: A surface core board 20 having copper-plated through holes 2010 and a single-sided stepped circuit pattern 2020 is manufactured; the stepped circuit pattern 2020 is composed of a completely etched circuit pattern 2020A in the circuit pattern area 1010 and an incompletely etched circuit pattern 2020B in the gold finger area 1020 .

[0030] In this embodiment, the surface core board 20 is manufactured as follows: a through hole is manufactured on a double-sided copper clad laminate and electroplated to form a copper-plated through hole 2010, which provides a conductive path for electroplating gold fingers in the subsequent process; a first dry film pattern is manufactured on the first side of the double-sided copper clad laminate, and a first etching is performed. The first dry film pattern is manufactured for the circuit pattern area 1010 and the gold finger area 1020. After the first etching, the circuit patterns of the circuit pattern area 1010 and the gold finger area 1020 are both incompletely etched circuit patterns 1020A, which provides a processing basis for the second etching to form a step circuit pattern 2020; and the gold finger area on the first side is etched. 1020 makes a second dry film pattern, that is, the incompletely etched circuit pattern 2020B in the gold finger area 1020 is covered with a second dry film pattern to form protection, and then a second etching is performed, and then the film is stripped. At this time, the circuit pattern of the circuit pattern area 1010 forms a completely etched circuit pattern 2020A, while the incompletely etched circuit pattern 2020B in the gold finger area 1020 is not etched, and the stepped circuit pattern 2020 is combined to form a surface core board 20; the other complete copper surface of the double-sided copper clad laminate provides a processing basis for the subsequent lamination process, ensuring that the board surface of the circuit board is evenly stressed during lamination, thereby increasing the reliability of the circuit board.

[0031] In the above-mentioned production of the stepped circuit pattern 2020, in the subsequent lamination process, the completely etched circuit pattern 2020A is overlapped with the semi-cured sheet to form a bonding effect, and the incompletely etched circuit pattern 2020B is overlapped with the release layer 3020 to form a non-bonding effect, thereby forming a non-bonding area. If the non-bonding area is directly and completely etched to become the completely etched circuit pattern 2020A, problems such as circuit bending or deviation may easily occur during the lamination process. Therefore, the stepped circuit pattern 2020 effectively avoids the occurrence of problems such as circuit bending, deviation or short circuit during lamination. The step-by-step and zoned etching process used in the production of the stepped circuit pattern 2020 allows each step to be optimized independently, which can better control the etching process, reduce rework caused by improper etching, and improve processing quality.

[0032] In the present embodiment, the copper-plated through hole 2010 is close to the area of ​​the incompletely etched circuit pattern 2020B, that is, the copper-plated through hole 2010 is adjacent to the gold finger area 1020; because the release layer 3020 in the subsequent process is extended on one side to cover the position of the copper-plated through hole 2010, the position of the copper-plated through hole 2010 affects the size of the release layer 3020, so the copper-plated through hole 2010 is adjacent to the gold finger area 1020, so that the area of ​​the release layer 3020 is the minimum area under the premise of ensuring the realization of the technology of the present invention. Furthermore, since the area of ​​the release layer 3020 is smaller, the incompletely etched circuit pattern 2020B overlaps with the release layer 3020 to form a non-bonded area, and it is less likely to have problems such as circuit bending or deviation during the pressing process.

[0033] Furthermore, after the first etching, the etching remaining thickness of the circuit pattern in the circuit pattern area 1010 is 3 microns to 8 microns; that is, the copper layer with the remaining thickness after the first etching is the connecting copper layer 2020C, and the thickness of the connecting copper layer 2020C is 3 microns to 8 microns, which provides a processing basis for the subsequent formation of the step circuit pattern 2020; the second etching is selective etching, and the circuit pattern of the gold finger area 1020 is protected by a dry film, and then the connecting copper layer 2020C of the circuit pattern area 1010 is completely etched away to form a completely etched circuit pattern 2020A.

[0034] In this embodiment, the copper-plated through hole 2010 is a microhole. Since the microhole has a small aperture during the subsequent pressing process, a solid effect can be formed through pressure, which can better prevent pressing deformation and prevent further processing such as delamination and board bursting caused by the hole position. Furthermore, laser drilling or mechanical drilling and other processing technologies can be used. The size of the microhole formed by laser drilling is 20 microns to 30 microns, and the size of the microhole formed by mechanical drilling is 0.15mm to 0.25mm.

[0035] See also Figure 5 , Figure 5 For use of the embodiments of the present invention Figure 3Schematic diagram of the cross-sectional structure of the stacked structure formed by the AA section.

[0036] Step S20: Take the semi-cured sheet, make a window pattern 3010, and set a release layer 3020 in the window pattern 3010 to form an intermediate core board 30; the release layer 3020 corresponds to the gold finger area 1020 and extends to cover the area where the copper-plated through hole 2010 is located.

[0037] It is worth mentioning that since the release layer 3020 needs to be removed in the subsequent process and cannot form a bonding effect with the surface core board 20, it is easy to move in the window pattern 3010 during the lamination process. Therefore, one side of the release layer 3020 extends to cover the copper-plated through hole 2010, but does not exceed the edge of the board. This can effectively prevent the release layer 3020 from falling off or being displaced after lamination and extrusion. Furthermore, it also provides a good processing foundation for the subsequent processing steps.

[0038] In this embodiment, since the sheet material is prone to expansion and contraction during the pressing process, the "copper layer" in the invalid area 102 is prone to enter the gold finger area 1020. When the subsequent process is formed and punched according to the original design, the excess "copper layer" entering the gold finger area 1020 cannot be removed, resulting in an incompletely etched circuit pattern 2020B connected to the gold finger area 1020, resulting in a circuit short circuit. Therefore, the other sides of the release layer 3020 are larger than the gold finger area 1020, preferably 20 microns to 50 microns.

[0039] In this embodiment, the material of the release layer 3020 is: PI material, PTFE material or low-flow glue semi-cured sheet. Compared with the ordinary epoxy resin-glass fiber material commonly used in circuit boards, the material of the release layer 3020 has stronger inertness and can form a non-bonding effect with the material of the circuit board, thereby forming a release effect.

[0040] Please refer again Figure 5 , and see Figure 6 and Figure 7 , Figure 6 For use of the embodiments of the present invention Figure 4 Schematic diagram of the cross-sectional structure of the laminated plate formed by the middle BB section; Figure 7 For the implementation of the present invention Figure 6 Schematic diagram of the CC plane structure of the pressed plate.

[0041] Step S30: The middle core board 30 is arranged between the two layers of surface core boards 20 to form a stacked structure 40, which is then pressed together to form a pressed board 50; the stepped circuit patterns 2020 of the two layers of surface core boards 20 in the stacked structure 40 are arranged relatively, and the copper-plated through holes 2010 are located in the area of ​​the release layer 3020.

[0042] Since the release layer 3020 is provided in the window pattern 3010, that is, the window pattern 3010 restricts the movement of the release layer 3020, and the plate expands and shrinks during the lamination process, when the copper sheet of the window pattern 3010 is squeezed toward the release layer 3020, the release layer 3020 is squeezed, resulting in problems such as poor lamination of the laminated plate 50 and local protrusions. Therefore, in this embodiment, the release layer 3020 is smaller than the window pattern 3010 on one side, preferably smaller than 20 microns to 50 microns, to provide expansion and contraction space for the plate during the lamination process, effectively avoid the occurrence of problems such as poor lamination, and also provide a good board surface foundation for subsequent processing steps.

[0043] During the lamination process, the colloid of the semi-cured sheet is easy to flow, which may cause the copper layer in the invalid area 102 to enter the range of the molding line 10. After molding, the copper layer cannot be completely removed, resulting in problems such as line short circuit. Therefore, in this embodiment, the stepped circuit pattern 2020 extends to the invalid area 102, effectively preventing the copper layer in the invalid area 102 from entering the molding line during lamination.

[0044] See also Figure 8 , Figure 8 For the implementation of the present invention Figure 6 Schematic diagram of the cross-sectional structure of the plate edge groove formed by the pressed plate processing.

[0045] Step S40: The laminated board 50 is sequentially processed with surface circuit patterns, dry film patterns 6010 and controlled depth milling to expose a partial release layer 3020 , and then the release layer 3020 is removed to form a board edge groove board 60 .

[0046] Different from the common processing method that arranges the production of surface circuit graphics in the process before forming and punching, in the present embodiment, the surface circuit graphics are produced on the laminated board 50. On the one hand, after the release layer 3020 is removed in the later process, the board body of the laminated board 50 forms an initial depression 6020. If the surface circuit graphics are produced at this time, the pressing force when the dry film is pressed will cause the board surface to be depressed, resulting in the problem of loose film adhesion, leading to problems such as circuit short circuit; on the other hand, the electroplating process in the later process involves a relatively high temperature process. Under this temperature condition, the dry film and the copper layer of the surface core board 20 will form a strong bonding layer, which is not conducive to the subsequent production of the surface circuit graphics.

[0047] Furthermore, a dry film pattern 6010 is produced after the surface circuit pattern, which plays a protective and isolating role for the circuit pattern on the board surface of the laminated board 50, preventing the micro-etching and gold plating in the subsequent process from affecting the surface circuit pattern, and effectively avoiding the occurrence of problems such as circuit short circuit.

[0048] In this embodiment, the controlled depth milling is performed in the area where the release layer 3020 exceeds the copper-plated through hole 2010 along the controlled depth milling line 5010, and the depth of the milling is from the board surface to the surface of the release layer 3020. In particular, the controlled depth milling line 5010 is located in the area between the copper-plated through hole 2010 and the edge of the release layer 3020. After the controlled depth area and the board edge area are milled, a structure is formed in which the release layer 3020 protrudes from the edge of the board for easy removal, and then the release layer 3020 is removed to form an initial depression 6020.

[0049] In this embodiment, the dry film pattern 6010 is a plating chuck position 6030 that exposes the gold-plated finger, providing a conductive condition for forming a conductive channel.

[0050] See also Fig. 9 and Fig.10 , Fig. 9 For the implementation of the present invention Figure 8 Schematic diagram of the cross-sectional structure of the gold finger board formed by processing the board edge groove board; Fig.10 For the implementation of the present invention Fig. 9 Schematic diagram of the cross-sectional structure of a circuit board with an internal socket on the edge of the board formed by processing a gold finger board.

[0051] Step S50: The board edge groove plate 60 is micro-etched to etch the remaining incomplete etched circuit pattern 2020B from the previous step (i.e., the remaining 3 microns to 8 microns of connecting copper layer 2020C), so that the incomplete etched circuit pattern 2020B forms a gold finger circuit, and then gold is electroplated to form a gold finger 7010, and the board body forms a gold finger plate 60A, the entire board is formed, and then the film is stripped to form a circuit board 70 with an inner socket on the board edge.

[0052] In this embodiment, during the above-mentioned process of making the surface core board 20, a conductive circuit pattern is also produced in the invalid area 102, and the conductive circuit pattern connects the electroplating clamp position 6030 and the copper-plated through hole 1020, forming a conductive channel loop as a whole, providing conductive conditions for the electroplating of the gold finger 7010.

[0053] 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 circuit board with an inner socket on the edge of the board, characterized in that: The area within the range of the forming line of the circuit board during the processing is the effective area, and the remaining area is the invalid area. The effective area of ​​the circuit board includes a circuit pattern area and a gold finger area. The gold finger area corresponds to the inner socket of the board edge. The manufacturing method includes the following steps: S10: manufacturing a surface core board having copper-plated through holes and a stepped circuit pattern on one side; The step circuit pattern is composed of a completely etched circuit pattern in the circuit pattern area and an incompletely etched circuit pattern in the gold finger area; The copper plated through hole is close to the area of ​​the incompletely etched circuit pattern; S20: taking the prepreg, making a window pattern, and setting a release layer in the window pattern to form an intermediate core board; The release layer corresponds to the gold finger area and extends to cover the area where the copper-plated through hole is located; S30: placing the middle core board between the two layers of the surface core boards to form a stacked structure, and then pressing them together to form a pressed board; The stepped circuit patterns of the two layers of the surface core boards in the stacked structure are arranged opposite to each other, and the copper-plated through holes are located in the area of ​​the release layer; S40: forming a surface circuit pattern, a dry film pattern, and depth-controlled milling on the laminated board in sequence to expose a portion of the release layer, and then removing the release layer to form a board edge groove board; The controlled depth milling is to perform milling in the area of ​​the release layer beyond the copper-plated through hole, and the depth of the milling is from the board surface to the surface of the release layer; S50: micro-etching the groove plate at the edge of the board, forming the incompletely etched circuit into a gold finger circuit, electroplating the gold finger, forming the whole board, and then stripping the film to form the circuit board.

2. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: The surface core board is manufactured by: making through holes in a double-sided copper-clad laminate and electroplating to form the copper-plated through holes, then making a first dry film pattern on the first side of the double-sided copper-clad laminate, performing a first etching, then making a second dry film pattern on the gold finger area of ​​the first side, performing a second etching, and then stripping the film to form a stepped circuit to form the surface core board.

3. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 2, characterized in that: After the first etching, the etching residual thickness of the circuit pattern in the circuit pattern area is 3 microns to 8 microns; the second etching is to form the completely etched circuit pattern.

4. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: The release layer has a single side larger than the gold finger area.

5. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: The step circuit pattern extends to the invalid area.

6. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: The copper-plated through-hole is a micro-hole.

7. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: One side of the release layer is smaller than the window pattern.

8. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 2, characterized in that: The dry film pattern is the electroplating chuck position where the electroplating gold finger is exposed.

9. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 8, characterized in that: The manufacturing of the surface core board includes manufacturing a conductive circuit pattern on the ineffective area, wherein the conductive circuit pattern connects the electroplating clamp position and the copper-plated through hole.

10. A method for manufacturing a circuit board with an inner socket on the edge of a board as claimed in claim 1, characterized in that: The material of the release layer is: PI material, PTFE material or low-flow prepreg.

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