Manufacturing method of multi-layer encircling type high-shielding circuit board

Abstract

The invention discloses a manufacturing method of a multi-layer encircling type high-shielding circuit board, which comprises the following steps of: manufacturing a top-layer shielding circuit on a copper layer on one side by using a double-sided copper-clad plate to form a top-layer core plate; taking a plurality of double-sided copper-clad plates, and respectively manufacturing horizontal shielding patterns and shielding circuits on upper and lower copper layers of the double-sided copper-clad plates to form a plurality of double-sided copper-clad core plates; laminating and laminating a single-sided copper-clad plate, a prepreg and the two core plates to form a laminated plate; milling a through groove in the laminated plate and filling the through groove to form a vertical shielding area and a shielding plate; manufacturing a surface circuit for the shielding plate and performing post-process processing to form a high-shielding circuit board; through the method of milling the through groove and then filling, the problem that in the prior art, high shielding is achieved by embedding a U-shaped copper block and then electroplating and encircling, and consequently the thickness of the circuit board is large is solved. By directly arranging the pattern on each layer, the effects of reducing the board thickness and improving the processing efficiency and precision are achieved, the front and back flows of the whole manufacturing process are effectively matched, and the high-precision and thin multi-layer surrounding type high-shielding circuit board structure is achieved.

Description

Technical Field

[0001] The invention relates to the field of flexible circuit board manufacturing, and in particular to a method for manufacturing a multi-layer enclosed high-shielding circuit board. Background Art

[0002] The prior art method for manufacturing a multi-layer circuit board with an inner layer high shielding line generally involves first burying a U-shaped copper block, then pressing the high shielding line into the U-shaped copper block, and then electroplating a copper layer on the surface to form a closed area with the U-shaped copper block, thereby forming a high shielding line structure in the closed area.

[0003] The above-mentioned manufacturing methods all have limitations, because the U-shaped copper block is buried and then pressed together to form a high-shielded circuit. Since the U-shaped copper block itself has a relatively thick thickness and is pressed together, the overall pressed board is thicker. When multiple layers are pressed together (between partitions), semi-cured sheets need to be added between multiple unit layers to assist in pressing, which further increases the thickness. The semi-cured sheets can only form high-shielded circuits within the closed area of ​​the unit layer, and the other layers can only form bonding layers or ordinary circuit layers. The function of each layer is relatively single, which will waste the wiring space between layers.

[0004] Therefore, the above-mentioned prior art manufacturing method is difficult to meet the design and processing requirements of some multi-layer circuit boards that require high shielding properties and thinness.

[0005] Therefore, in order to solve the problems raised by the above background technology, it is necessary to provide a method for manufacturing a multi-layer enclosed high-shielding circuit board. Summary of the invention

[0006] The present invention aims to solve the problem that the flexible circuit board in the prior art requires comprehensive performance such as high-fidelity signal and convenient processing, and proposes a method for manufacturing a multi-layer enclosed high-shielding circuit board, which comprises the following steps: S10: Take a double-sided copper-clad board and make a top-layer shielding circuit on one copper layer of the board to form a top-layer core board; S20: taking a plurality of double-sided copper-clad boards, making horizontal shielding patterns on the upper copper layer, and making shielding lines on the lower copper layer, to form a plurality of double-sided copper-clad core boards; S30: Take a single-sided copper clad laminate and a prepreg, and stack them with a number of the double-sided copper clad core boards and the top core board to form a stacked structure, and then press them together to form a laminated board; the top shielding line in the stacked structure is relatively overlapped with the insulating medium layer of the single-sided copper clad laminate, and a number of the double-sided copper clad core boards are stacked between the two; the stacked structure includes arranging the prepreg between each layer of the double-sided copper clad core boards, and between the top core board and the double-sided copper clad core board; the area corresponding to the horizontal shielding pattern of the laminated board is the horizontal shielding area; S40: milling a through groove on the edge of the horizontal shielding area of ​​the pressed plate parallel to the arrangement direction of the shielding circuit, and filling it to form a vertical shielding area, and the whole is processed to form a shielding plate; S50: manufacturing a surface circuit on the surface copper layer of the shielding plate, and performing post-processing to form the high-shielding circuit board; the surface circuit includes a circuit pattern covering the horizontal shielding area.

[0007] Furthermore, the manufacturing of the shielding circuit includes manufacturing a reinforcement circuit, and the reinforcement circuit extends from the horizontal shielding area to the vertical shielding area.

[0008] Furthermore, the horizontal shielding pattern extends toward the vertical shielding area to form an extended line.

[0009] Furthermore, the horizontal shielding pattern in the stacked structure faces the top core board.

[0010] Furthermore, the milling of the through groove includes milling a side wall of the through groove close to the horizontal shielding area to form a regular concave-convex pattern.

[0011] Furthermore, the milling of the through slot includes drilling a through hole on a side wall of the through slot close to the horizontal shielding area.

[0012] Furthermore, the filling is performed by electroplating copper on the through groove.

[0013] Furthermore, the filling is performed by electroplating solid copper on the through slot.

[0014] Furthermore, the filling is to fill the through groove with conductive copper paste or conductive silver paste.

[0015] Furthermore, it includes drilling a blind hole in the shielding plate, wherein the blind hole connects the surface circuit and the shielding circuit.

[0016] The technical solution of the present invention adopts the method of directly setting shielding plane graphics on each layer of core board, laminating between layers, and then milling through grooves in the vertical direction and filling them to form a plurality of enclosed high-shielding units, so as to achieve the effect of interlayer continuity of each shielding unit, thereby solving the problem that the prior art makes graphics in different regions of U-shaped copper block and then presses multiple layers, and each layer has a relatively single function, resulting in a waste of interlayer wiring space; by adopting the method of milling through grooves and then filling them, the copper wall thickness of the through grooves can be controlled, thereby solving the problem that the prior art achieves a high shielding effect by burying U-shaped copper blocks and then electroplating to form an enclosed structure, but resulting in a large thickness of the circuit board; by directly setting graphics on each layer, the board thickness can be reduced, and the processing efficiency and processing accuracy can be improved. The overall production process has the effective coordination of the front and back processes to achieve a high-precision, thinner multi-layer enclosed structure high-shielding circuit board. 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 It is a schematic diagram of the cross-sectional structure of a prior art enclosed high-shielding circuit board; Figure 2 A schematic diagram of a process flow of a circuit board according to an embodiment of the present invention; Figure 3 A schematic diagram of a stacked structure according to an embodiment of the present invention; Figure 4 It is a schematic diagram of a stacked structure with a reinforcement circuit and an extension circuit according to an embodiment of the present invention; Figure 5 is a schematic cross-sectional view of a pressed plate according to an embodiment of the present invention; Figure 6 A schematic plan view of a pressed plate with blind holes drilled therein according to an embodiment of the present invention; Figure 7 for Figure 6 AA cross-section diagram of ; Figure 8 is a schematic cross-sectional view of a shielding plate according to an embodiment of the present invention; Fig. 9 It is a schematic cross-sectional view of a high shielding circuit board according to an embodiment of the present invention.

[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 It is a structural schematic diagram of a prior art enclosed high-shielding circuit board.

[0026] The manufacturing method of the prior art is to set up a prior art buried U-shaped copper block 120, then press the prior art shielding circuit 110 into the prior art buried U-shaped copper block 120, and then electroplate a copper layer 130 on the surface to form a high shielding circuit structure in a closed area with the prior art buried U-shaped copper block 120.

[0027] See also Figure 2 , Figure 2 Schematic diagram of the process flow of an embodiment of the present invention.

[0028] The manufacturing process of the embodiment of the present invention includes using Figure 2 The following will implement the various steps in the process Figure 2 Each step in the process is further explained step by step.

[0029] See also Figure 3 , Figure 3 It is a schematic diagram of the stacked structure of an embodiment of the present invention.

[0030] Step S10: A double-sided copper clad laminate is taken and a top-level shielding circuit 1010 is made on one side of the copper layer to form a top-level core board 100, while no circuit pattern is made on the other side of the top-level copper layer 1020; in the subsequent pressing process, the conditions of high temperature and high pressure can ensure the close bonding of the core boards, but if circuits are made on both sides of the copper layers and then pressed, the circuit board may warp and deform due to uneven distribution of the surface copper during the pressing process, causing damage to the circuit, thereby affecting the normal function of the circuit. Therefore, in this embodiment, the copper layer on one side of the top-level core board 100 is retained, and the complete copper surface is used as the surface copper layer to ensure that the circuit board is evenly stressed, thereby providing a pressing basis for subsequent pressing.

[0031] Step S20: Then take several double-sided copper clad laminates, make horizontal shielding patterns 2010 on the upper copper layer, and make shielding lines 2020 on the lower copper layer, to form several double-sided copper clad core boards 200. In this embodiment, a horizontal shielding pattern 2010 is made on one copper surface of several double-sided copper clad laminates, and a shielding line 2020 is made on the other surface. After subsequent multi-layer stacking, the horizontal shielding pattern 2010 between the two layers and the vertical shielding areas 3010A on both sides that are subsequently made will enclose the shielding line 2020 in the middle to form several enclosed shielding units. Therefore, the horizontal shielding patterns 2010 and shielding lines 2020 of several double-sided copper clad laminates that are made on different surfaces provide a basis for the subsequent formation of several shielding units.

[0032] See also Figure 4 , Figure 4 It is a schematic diagram of a stacked structure with reinforced circuits and extended circuits according to an embodiment of the present invention.

[0033] In this embodiment, the manufacturing of the shielding circuit 2020 includes manufacturing a reinforcement circuit 2021, which extends from the horizontal shielding area 2010A to the vertical shielding area 3010A, providing better interlayer bonding force for the subsequent manufacturing of the vertical shielding area 3010A with a through-groove structure, thereby forming a more solid vertical shielding area 3010A.

[0034] In this embodiment, the horizontal shielding pattern 2010 extends toward the vertical shielding area 3010A to form an extension circuit 2022 , which has the same function as the above-mentioned reinforcement circuit 2021 and is not further described.

[0035] Please continue reading Figure 3 and Figure 4 , and see Figure 5 ; Figure 5 It is a schematic cross-sectional view of a pressed plate according to an embodiment of the present invention.

[0036] Step S30: The single-sided copper clad laminate 300 and the prepreg 400 are stacked with a plurality of double-sided copper clad core boards 200 and a top core board 100 to form a stacked structure 20 , which is then pressed together to form a pressed board 30 .

[0037] It is worth noting that the top-layer shielding circuit 1010 in the stacked structure 20 is relatively overlapped with the insulating medium layer 310 of the single-sided copper clad laminate 300, and the copper layer 320 of the single-sided copper clad laminate is not patterned, so that when pressed, the top-layer copper layer 1020 and the single-sided copper clad laminate copper layer 320 are both complete copper surfaces without patterns, ensuring that the two surface copper layers are evenly stressed when the entire stacked structure 20 is pressed, and the interlayer bonding is tighter; and a number of double-sided copper clad core boards 200 are stacked between the two. Since the two copper layers of the double-sided copper clad laminates 200 are respectively made with horizontal shielding patterns 2010 and shielding circuits 2020, neither can be used as the surface copper layer during pressing. Therefore, the double-sided copper clad laminates 200 can only participate in pressing as the core boards of the middle layer.

[0038] It is worth explaining that the single-sided copper clad laminate 300 is placed at the bottom layer of the stacked structure 20 in order to form an enclosed shielding structure for the shielding circuit 2020 on the adjacent double-sided copper clad core laminate 200 together with the horizontal shielding pattern 2010 of the adjacent double-sided copper clad core laminate 200 and the subsequently produced vertical shielding area 3010A, so that the copper layer 320 of the single-sided copper clad laminate (subsequently produced to form the surface circuit 4010) becomes one of the sides of the enclosed structure, further forming an overall enclosed structure from the surface layer to the core layer of the overall circuit board, rather than using the double-sided copper clad laminate to be placed at the bottom layer, so that after the high-shielding flexible circuit board is produced, an empty layer without shielding circuit distribution is formed inside the layer of the double-sided copper clad laminate, causing the overall enclosed structure to have an "extra insulating dielectric layer" phenomenon.

[0039] In addition, the stacked structure 20 includes a semi-cured sheet 400 arranged between each layer of double-sided copper clad core board 200, and between the top core board 100 and the double-sided copper clad core board 200; the semi-cured sheet 400 serves as a key layer in the circuit board lamination. The epoxy resin of the semi-cured sheet 400, under the action of heat and pressure, bonds the various layers of the core boards together and forms a reliable insulating layer, providing the necessary electrical insulation to protect the circuit from external interference and damage.

[0040] It is worth noting that the area corresponding to the horizontal shielding pattern 2010 of the pressed plate 30 is the horizontal shielding area 2010A, which forms an enclosed structure with the vertical shielding area 3010A formed by subsequent processing to form a high shielding area.

[0041] In this embodiment, the horizontal shielding pattern 2010 in the stacked structure 20 faces the top core board 100. Figure 3 or Figure 4As shown, the copper surfaces of the horizontal shielding patterns 2010 of several double-sided copper clad core boards 200 are all facing upwards, and as the horizontal shielding patterns 2010 are pressed together, a horizontal shielding area 2010A is formed inside the pressed board 30 and connected to the subsequent vertical shielding area 3010A to form an enclosure structure of several unit structures, and the enclosure structure encloses the shielding line 2020 in the middle for shielding protection, thereby meeting the processing requirements of multi-layer enclosed high-shielding circuit boards.

[0042] See also Figure 6 , Figure 7 and Figure 8 , Figure 6 A schematic plan view of a pressed plate with blind holes drilled therein according to an embodiment of the present invention; Figure 7 for Figure 6 8 is a schematic cross-sectional view of the shielding plate according to an embodiment of the present invention.

[0043] Step S40: The through groove 3010 is milled and filled on the edge of the horizontal shielding area 2010A of the pressing plate 30 which is parallel to the arrangement direction of the shielding circuit 2020 to form a vertical shielding area 3010A, and the shielding plate 40 is formed by overall processing.

[0044] In this embodiment, the milling of the through slot 3010 includes drilling a through hole in the side wall of the through slot 3010 close to the horizontal shielding area 3010A, that is, drilling a half hole 3011 on the edge of the side wall of the through slot 3010. Since the through slot 3010 needs to be filled or electroplated in the subsequent process, drilling the half hole 3011 allows the shielding side wall to form a reinforcement structure with a certain protrusion, thereby increasing the contact area between the side wall of the through slot 3010 and the electroplated copper layer, and increasing the bonding force between the two, so that the bonding between the through slot filling slurry or the electroplated copper layer and the side wall is more stably.

[0045] In this embodiment, a blind hole 3012 is drilled and electroplated on the pressing plate 30, and the blind hole 3012 connects the surface circuit and the shielding circuit 2020, thereby achieving connectivity between the surface circuit 4010 and the shielding circuit 2020 below. This connection method not only increases the space utilization between the layers of the circuit board, but also reduces electromagnetic interference on the circuit board.

[0046] In one embodiment, milling the through groove 3010 includes milling the side wall of the through groove 3010 close to the horizontal shielding area 2010A to form a regular concave-convex pattern (not shown in the drawings), which is consistent with the design of drilling a half hole 3011. When milling the through groove 3010, the milling cutter is used to mill and shape it in one go according to the design, so that the side wall of the through groove 3010 close to the horizontal shielding area 2010A is a regular concave-convex pattern. Because its effect is the same as that of drilling a half hole, it will not be repeated.

[0047] In this embodiment, the filling is to fill the through groove 3010 with conductive copper paste or conductive silver paste. Since conductive copper paste and conductive silver paste have high conductivity and good heat dissipation performance, filling with conductive copper paste or conductive silver paste can ensure the stable transmission of electronic signals and currents. Moreover, conductive silver paste, as a specially designed silver-containing material, contains fine silver particles, which can effectively reflect or absorb electromagnetic waves, block external electromagnetic radiation or interference signals, and is used for electromagnetic shielding and preventing electromagnetic radiation interference. In one embodiment, the filling is to electroplate a copper layer on the inner wall of the through slot 3010, which can ensure that the inside of the through slot is evenly covered by the copper layer, thereby improving the reliability of shielding.

[0048] In one embodiment, the filling is to electroplate solid copper on the through slot 3010. Filling the through slot with solid copper can reduce resistance, provide better shielding, and improve signal transmission speed and quality on the one hand, and increase the strength of the through slot on the other hand, prevent the through slot from cracking or delamination, thereby improving the reliability and service life of the circuit board.

[0049] See also Fig. 9 , Fig. 9 FIG. 1 is a schematic cross-sectional view of a high shielding circuit board according to an embodiment of the present invention.

[0050] Step S50: A surface circuit 4010 is made on the surface copper layer of the shielding plate 40, and post-processing is performed to form a high-shielding circuit board 50. The surface circuit 4010 includes a circuit pattern covering the horizontal shielding area 2010A and connected to the vertical shielding area 3010A, forming a complete enclosed closed structure on the top layer to achieve a high shielding effect.

[0051] In addition, the present embodiment of making the top-level shielding circuit 1010 and the making the horizontal shielding pattern 2010 both include making the tool pattern of the board edge tool area 3020, which plays the role of providing stable support and positioning reference, so that the machine can identify and grab the circuit board, thereby achieving efficient and high-precision production.

[0052] 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 multi-layer enclosed high-shielding circuit board, characterized in that: The production method comprises the following steps: S10: Take a double-sided copper-clad board and make a top-layer shielding circuit on one copper layer of the board to form a top-layer core board; S20: taking a plurality of double-sided copper-clad boards, making horizontal shielding patterns on the upper copper layer, and making shielding lines on the lower copper layer, to form a plurality of double-sided copper-clad core boards; S30: taking a single-sided copper clad laminate and a prepreg, and stacking them with a plurality of the double-sided copper clad core boards and the top core board to form a stacked structure, and then pressing them together to form a pressed board; The top shielding circuit in the stacked structure is relatively overlapped with the insulating medium layer of the single-sided copper-clad laminate, and a plurality of double-sided copper-clad core laminates are stacked between the two; The stacked structure includes arranging the prepreg between each layer of the double-sided copper clad core board and between the top core board and the double-sided copper clad core board; The area corresponding to the horizontal shielding pattern of the pressed plate is the horizontal shielding area; S40: milling a through groove on the edge of the horizontal shielding area of ​​the pressed plate parallel to the arrangement direction of the shielding circuit, and filling it to form a vertical shielding area, and the whole is processed to form a shielding plate; S50: making a surface circuit on the surface copper layer of the shielding plate, and performing post-processing to form the high-shielding circuit board; The surface circuit includes a circuit pattern covering the horizontal shielding area.

2. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The manufacturing of the shielding circuit includes manufacturing a reinforcement circuit, wherein the reinforcement circuit extends from the horizontal shielding area to the vertical shielding area.

3. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The horizontal shielding pattern extends toward the vertical shielding area to form an extended line.

4. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The horizontal shielding pattern in the stacked structure faces the top core board.

5. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The milling of the through-slot includes milling the side wall of the through-slot close to the horizontal shielding area to form a regular concave-convex pattern.

6. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The milling through-slot includes drilling a through hole on a side wall of the through-slot close to the horizontal shielding area.

7. A method for manufacturing a multi-layer enclosed high shielding circuit board as claimed in claim 1, 5 or 6, characterized in that: The filling is performed by electroplating copper on the through groove.

8. A method for manufacturing a multi-layer enclosed high shielding circuit board as claimed in claim 1, 5 or 6, characterized in that: The filling is performed by electroplating solid copper on the through groove.

9. A method for manufacturing a multi-layer enclosed high shielding circuit board as claimed in claim 1, 5 or 6, characterized in that: The filling is to fill the through groove with conductive copper paste or conductive silver paste.

10. The method for manufacturing a multi-layer enclosed high shielding circuit board according to claim 1, characterized in that: The method comprises drilling a blind hole on the shielding plate, wherein the blind hole connects the surface circuit and the shielding circuit.

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