A method for manufacturing a high-shielding embedded copper block circuit board

Abstract

The present invention discloses a method for manufacturing a high-shielding embedded copper block circuit board, which comprises the following steps: a prefabricated windowed prepreg, a first core board, a U-shaped copper block, and a second core board are stacked and pressed together in sequence from top to bottom according to corresponding patterns; the insulating dielectric layer of the first core board faces the through-groove structure of the U-shaped copper block, and the second circuit pattern of the second core board faces the bottom surface of the U-shaped copper block; the pressed board is polished twice in sequence and then electroplated to form an electroplated board; a surface circuit pattern is formed on the electroplated board to form a circuit pattern board; a surface prepreg is pressed onto the surface of the electroplated board, and then polished for a third time to form a high-shielding embedded copper block circuit board; the copper block is made into a U-shaped copper block, pressed together with a multi-layer structure to form a copper block embedded state, and then the surface copper layer is electroplated to form a closed structure, thereby achieving a high-shielding signal transmission effect of the circuit; the flattening process is designed to be multiple polishing and multiple electroplating, which is effectively coordinated with the pressing process before and after, thereby achieving high reliability in installation and application.

Description

Technical Field

[0001] The present invention relates to the field of circuit board manufacturing, and in particular to a method for manufacturing a high-shielding embedded copper block circuit board. Background Art

[0002] For a type of circuit board that needs to be used in high-precision communications or medical modules, it is usually required to have a high shielding structure to achieve high-fidelity and high-intensity signal transmission capabilities, that is, the circuit board has a high shielding area and a flat surface.

[0003] For this type of circuit board, the commonly used production method is: to form the circuit that needs to be shielded, and then use shielding film or make a shielding circuit graphic layer to form a shielding effect; the production method for smoothing the surface is to scrape the surface solder mask or increase the pressing force to form a flat surface.

[0004] The shielding effect layer formed by the above-mentioned production method generally only achieves the shielding effect in the planar direction. In order to improve the circuit shielding effect, the method of increasing the circuit spacing or increasing the circuit board area is usually adopted, but it will lead to a decrease in the circuit density of the circuit board and an excessive size, which is not conducive to the processing requirements of high-precision, small-size circuit board products; and as for the production effect of surface flatness, it is easy to cause the solder mask layer to be concave and the solder mask layer to cover the surface circuit, affecting the use of the surface circuit.

[0005] Therefore, in order to solve the problems raised in the above background technology, it is necessary to provide a method for manufacturing a high-shielding embedded copper block circuit board. Summary of the Invention

[0006] The present invention aims to solve the problem of flexible circuit boards in the prior art requiring high-fidelity signals and convenient processing, and proposes a method for manufacturing a high-shielding embedded copper block circuit board. The manufacturing method includes the following steps:

[0007] S10: taking a copper block and processing it into a U-shaped copper block with a through-groove structure;

[0008] S20: taking a prepreg and making a prepreg window pattern to form a windowed prepreg, wherein the prepreg window pattern corresponds to the side wall top surface pattern of the U-shaped copper block;

[0009] S30: Take a single-sided copper clad laminate, form a first circuit pattern on its copper layer, and form a core board window pattern corresponding to the prepreg window pattern on its insulating dielectric layer to form a first core board;

[0010] S40: Take a double-sided copper-clad laminate and form a second circuit pattern on one copper layer of the laminate to form a second core board;

[0011] S50: stacking the windowed prepreg, the first core board, the U-shaped copper block, and the second core board in sequence from top to bottom to form a stacked structure, and pressing them together to form a laminated board; the insulating dielectric layer of the first core board faces the through-groove structure of the U-shaped copper block, and the second circuit pattern of the second core board faces the bottom surface of the U-shaped copper block; the window pattern of the prepreg, the window pattern of the core board, and the top surface of the side wall of the U-shaped copper block are stacked correspondingly; one side of the prepreg of the laminated board is the upper surface, and the other side is the lower surface;

[0012] S60: performing a first grinding on the upper surface to expose the sidewall top surface of the U-shaped copper block, then performing a first electroplating to form a first electroplated copper layer, and then performing a second grinding and a second electroplating process to form an electroplated plate;

[0013] S70: forming a surface circuit pattern on the surface copper layer of the electroplating board to form a circuit pattern board;

[0014] S80: pressing a surface prepreg onto the surface of the circuit pattern board, and then performing a third polishing to form the high-shielding embedded copper block circuit board.

[0015] Furthermore, the top surface of the side wall of the U-shaped copper block is a serrated edge.

[0016] Furthermore, the first grinding is to completely grind the serrated edge.

[0017] Furthermore, the outer surface of the U-shaped copper block is a continuous concave-convex pattern.

[0018] Furthermore, the semi-cured sheet is a second single-sided copper clad laminate, and a circuit pattern is made on its copper layer to form a reinforced circuit, and the reinforced circuit is located within the range of the through-groove structure of the U-shaped copper block; the insulating dielectric layer of the second single-sided copper clad laminate faces the first core board.

[0019] Furthermore, the stacked structure includes: a first release film, a coating film, a second release film and a first steel plate are sequentially arranged on the windowed semi-cured sheet to form an upper surface auxiliary pressing structure; a third release film and a second steel plate are sequentially arranged under the second core plate to form a lower surface auxiliary pressing structure.

[0020] Furthermore, the first electroplating is electroplating the upper surface.

[0021] Furthermore, the thickness of the copper layer electroplated for the first time is 15 microns to 20 microns.

[0022] Furthermore, the second electroplating is whole-board electroplating.

[0023] Furthermore, the second polishing is for polishing the first electroplated copper layer, and the third polishing is for polishing the surface prepreg.

[0024] The technical solution of the present invention realizes the signal transmission effect of this type of circuit by forming a U-shaped copper block, pressing it with a multi-layer structure to form an embedded copper block, and then electroplating a surface copper layer to form a closed structure. It solves the shortcomings of the existing technology of using a shielding film or making a shielding circuit graphic layer to form a shielding effect, and improving the shielding performance by increasing the circuit gap or increasing the circuit board area; by designing the flattening process as multiple polishing and multiple electroplating methods, it forms an effective coordination with the pressing process before and after, has an overall effect, reduces the processing steps, and achieves high reliability during installation and application, and solves the problem of the existing technology of using scraping or increasing the pressing force to flatten the surface, which causes the solder mask to be concave. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0026] Figure 1 This is a key process flow chart for an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the three-dimensional structure of a U-shaped copper block according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic side structural diagram of a U-shaped copper block with serrated edges according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the main structure of a U-shaped copper block with a concave-convex pattern according to an embodiment of the present invention;

[0030] Figure 5 Schematic diagram of the typesetting structure of an embodiment of the present invention;

[0031] Figure 6 is a schematic cross-sectional view of a pressed plate according to an embodiment of the present invention;

[0032] Figure 7 Schematic cross-sectional view of a press plate with a reinforcement circuit according to an embodiment of the present invention;

[0033] Figure 8 Schematic cross-sectional view of a first polishing plate according to an embodiment of the present invention;

[0034] Figure 9 Schematic cross-sectional view of a first electroplating plate according to an embodiment of the present invention;

[0035] Figure 10 Schematic cross-sectional view of a second electroplating plate according to an embodiment of the present invention;

[0036] Figure 11 is a schematic cross-sectional view of a circuit pattern board according to an embodiment of the present invention;

[0037] Figure 12 This is a schematic cross-sectional structure diagram of a high-shielding embedded copper block circuit board according to an embodiment of the present invention.

[0038] Description of Figure Numbers:

[0039]

[0040] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] 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, etc.) are only used to explain the relative position relationship and movement status of the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0043] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0044] 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 this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] See also Figure 1 , Figure 1 Schematic diagram of the process flow of an embodiment of the present invention.

[0046] 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.

[0047] See also Figure 2 , Figure 2 Schematic diagram of the three-dimensional structure of a U-shaped copper block according to an embodiment of the present invention.

[0048] Step S10:

[0049] A copper block is taken and processed to form a U-shaped copper block 100 with a through-slot structure. In this embodiment, excess copper is removed by milling or etching the copper block to form a U-shaped through-slot structure as a whole, which provides a spatial basis for subsequently burying the circuit inside the through-slot structure.

[0050] See also Figure 3 , Figure 3 This is a schematic side structural diagram of a U-shaped copper block with serrated edges according to an embodiment of the present invention.

[0051] It is worth noting that the top surface of the side wall of the U-shaped copper block 100 is a serrated edge 110; by designing the edge of the copper block as a serrated edge 110, the contact area between the U-shaped copper block 100 and the insulating dielectric layer is increased, and the U-shaped copper block 100 has a certain pressure-bearing and buffering function during pressing, which is used to buffer the pressure it is subjected to during the pressing process.

[0052] See also Figure 4 , Figure 4 This is a schematic diagram of the main structure of a U-shaped copper block with a concave-convex pattern according to an embodiment of the present invention.

[0053] In one embodiment, the outer surface of the U-shaped copper block 100 is a continuous concave-convex pattern 120, such as a regular wavy pattern, which has a similar design effect to the serrated edge 110 described above. The edge of the concave-convex pattern 120 can increase the contact area between the outer surface of the U-shaped copper block 100 and the insulating dielectric layer, so that the U-shaped copper block 100 and the insulating dielectric layer can fit together more tightly during pressing, avoiding deviation caused by overly smooth side walls during pressing, thereby improving the stability and firmness of the pressing.

[0054] See also Figure 5 , Figure 5 Schematic diagram of the typesetting structure of an embodiment of the present invention.

[0055] Depend on Figure 5It can be seen that the stacked structure composed of the prepreg, the first core board, and the second core board, as well as the auxiliary pressing structures on the upper and lower surfaces thereof.

[0056] Step S20:

[0057] Take the semi-cured sheet and make a semi-cured sheet window pattern to form a windowed semi-cured sheet 200. The semi-cured sheet is a necessary layer for laminating multi-layer circuit boards. During lamination, the semi-cured sheet undergoes heat melting, flow, and solidification in sequence, and finally bonds the multi-layer boards together to form a reliable insulation layer. The window pattern of the windowed semi-cured sheet 200 corresponds to the side wall top surface pattern of the U-shaped copper block 100, which provides a lamination basis for the subsequent lamination of the windowed semi-cured sheet 200 and the U-shaped copper block 100 together without the windowed semi-cured sheet 200 covering the side wall top surface of the U-shaped copper block 100.

[0058] Step S30:

[0059] A single-sided copper clad laminate is taken, and a first circuit pattern 3010 is made on its copper layer, and a core board window pattern 3020 corresponding to the semi-cured sheet window pattern is made on its insulating dielectric layer to form a first core board 300; in this embodiment, the first core board 300 is a single-sided copper clad laminate. Considering the bonding effect between layers, subsequent pressing requires the insulating dielectric layer of the single-sided copper clad laminate to be laminated and pressed with the copper surface of the U-shaped copper block 100. If the other side is also set as a copper layer, then during pressing, the copper layer will contact the copper surface of the bottom surface of the U-shaped copper block 100, and no interlayer bonding effect can be formed. Moreover, the first circuit pattern 3010 corresponding to the through-groove structure cannot form a high-shielding circuit subsequently.

[0060] Step S40:

[0061] A double-sided copper clad laminate is taken, and a second circuit pattern 4010 is made on the copper layer on one side to form a second core board 400. In this embodiment, the copper layers on both sides of the second core board 400 respectively play different roles. One side is used to make the second circuit pattern 4010, and the other side provides a basic copper layer for subsequent electroplating of copper layers and making surface circuit patterns, making processing more convenient, and continuing electroplating on the original copper layer can ensure the flatness and uniformity of the electroplating.

[0062] See also Figure 6 and Figure 7 , Figure 6 is a schematic cross-sectional view of a pressed plate according to an embodiment of the present invention; Figure 7 Schematic cross-sectional view of a laminated plate with a reinforcement circuit according to an embodiment of the present invention.

[0063] Step S50:

[0064] The windowed semi-cured sheet 200, the first core board 300, the U-shaped copper block 100 and the second core board 400 are stacked in sequence from top to bottom to form a stacked structure 20, and pressed together to form a pressed board 30; the insulating dielectric layer of the first core board 300 faces the through-groove structure of the U-shaped copper block 100, and the second circuit pattern 4010 of the second core board 400 faces the bottom surface of the U-shaped copper block 100; the pattern of the windowed semi-cured sheet 200, the core board window pattern 3020 and the side wall top surface of the U-shaped copper block 100 are stacked correspondingly; one side of the semi-cured sheet of the pressed board 30 is the upper surface, and the other side is the lower surface.

[0065] In one embodiment, the semi-cured sheet is a second single-sided copper clad laminate, and a circuit pattern is made on its copper layer to form an enhanced circuit 210. After pressing, the enhanced circuit 210 is arranged within the range of the through-groove structure of the U-shaped copper block 100; that is, the enhanced circuit 210 is located above the middle area of ​​the through-groove structure, providing stronger copper surface adhesion for the subsequent first electroplating, ensuring that the electroplated copper layer within the surface range of the through-groove structure opening of the U-shaped copper block 100 has stronger adhesion, and preventing problems such as copper bubbles and falling off during subsequent polishing and circuit board application processing; at the same time, it is worth noting that the insulating dielectric layer of the second single-sided copper clad laminate faces the first core board 300 to avoid the two copper layers from failing to achieve the pressing effect when they are pressed relative to each other. Therefore, the insulating dielectric layer faces the circuit pattern of the first core board 300, so as to ensure that the copper layer and the insulating dielectric layer are pressed stably.

[0066] The key feature of the present invention is that each layer is made separately, and the patterns of each layer are matched, and then the layers are laminated and pressed to form a pressed plate 30.

[0067] It is worth noting that the lamination process requires the participation of an auxiliary lamination structure to complete the process. The stacked structure 20 includes: a first release film 5010, a coating film 5020, a second release film 5030 and a first steel plate 5040 are sequentially arranged on the windowed semi-cured sheet 200 to form an upper surface auxiliary lamination structure 500; and a third release film 6010 and a second steel plate 6020 are sequentially arranged under the second core plate to form a lower surface auxiliary lamination structure 600.

[0068] In this embodiment, the upper surface auxiliary pressing structure 500 adopts a structural setting with a coating layer, which is used to provide coating ability during the pressing process, ensure coating from the opening direction of the through-groove structure of the U-shaped copper block 100, and form coating filling between layers and between each layer and the U-shaped copper block 100; the lower surface auxiliary pressing structure 600 adopts a structural setting without a coating layer, so that the lower surface provides stronger flatness support, ensures the support of the U-shaped copper block 100 during pressing, ensures the flatness of the lower surface, and prevents the lower surface coating from causing problems such as skewness.

[0069] See also Figure 8 、 Figure 9 and Figure 10 , Figure 8 Schematic cross-sectional view of a first polishing plate according to an embodiment of the present invention;

[0070] Figure 9 Schematic cross-sectional view of a first electroplating plate according to an embodiment of the present invention; Figure 10 It is a cross-sectional schematic diagram of the second electroplating plate according to an embodiment of the present invention.

[0071] Step S60:

[0072] The upper surface of the press plate 30 is first polished to expose the sidewall top surface of the U-shaped copper block 100, forming a polished plate 40. Then, a first electroplating process is performed to form a first electroplated plate 50 having a first electroplated copper layer 510. Then, a second polishing and second electroplating process are performed to form a plated plate 60.

[0073] It is worth noting that the formed pressing plate 30 has a pressing protrusion 310 at the pressing point with the top of the U-shaped copper block 100. The first grinding is to grind the pressing protrusion 310 flat to form a first grinding plane 410, exposing the top surface of the side wall of the U-shaped copper block 100.

[0074] When using the design of the serrated edge 110, the first grinding needs to completely grind the serrated edge 110 to form a first grinding plane 410 to avoid the unevenness of the copper surface after grinding, which fails to expose the top surface of the side wall of the U-shaped copper block 100. Subsequent upper surface electroplating may cause the high shielding area to fail to be enclosed, resulting in poor shielding of the circuit board.

[0075] In particular, the first electroplating is for electroplating the upper surface, and the thickness of the first electroplated copper layer 510 formed by the first electroplating is 15 microns to 20 microns, so that both the upper and lower surfaces of the press plate 30 have copper surfaces, providing an electroplating basis for the second whole-board electroplating.

[0076] In particular, the second polishing is to polish the first electroplated copper layer 510. Since the side wall top surface of the U-shaped copper block 100 is exposed after the first polishing, during the first electroplating, the copper coating speed of the side wall top surface of the U-shaped copper block 100 is faster than that of the copper-free area. Therefore, the electroplated copper thickness formed on the side wall top surface of the U-shaped copper block 100 is thicker than that of the copper-free area, and the surface is uneven. Therefore, a second polishing is required, and the second polishing polishes the first electroplated copper layer 510 to be consistent with the thickness of the lower surface copper layer 320 of the press plate 30, so that the upper and lower surface copper layers of the press plate 30 have the same thickness, and then the second electroplating is performed; the second electroplating is to electroplate the entire press plate 30, so that the second electroplated copper thickness 610 of the circuit board meets the requirements, providing a copper thickness foundation for subsequent surface circuit pattern making.

[0077] See also Figure 11 , Figure 11 Schematic cross-sectional view of a circuit pattern board according to an embodiment of the present invention.

[0078] Step S70:

[0079] A surface circuit pattern 620 is formed on the surface copper layer of the electroplated plate 60 to form a circuit pattern board 70. The surface area of ​​the through-slot structure opening of the U-shaped copper block 100 is formed into a fully covered surface circuit pattern 620, and is formed into a whole with the top surface of the side wall of the U-shaped copper block 100 through electroplating. At this time, the first circuit pattern 3010 inside the through-slot structure of the U-shaped copper block 100 is completely wrapped by the copper layer on all four sides, creating a circuit distribution effect, that is, forming an enclosed shielding cage, effectively improving the shielding effect of the circuit and realizing the effective transmission of high-fidelity and high-intensity signals.

[0080] See also Figure 12 , Figure 12 This is a schematic cross-sectional structure diagram of a high-shielding embedded copper block circuit board according to an embodiment of the present invention.

[0081] Step S80:

[0082] The surface semi-cured sheet 710 is pressed onto the surface of the circuit graphic board 70, and then polished for the third time to form a high-shielding embedded copper block circuit board 80; the surface semi-cured sheet 710 of this embodiment fills the gaps between the surface circuits, so that the surface circuits are "embedded" on the surface of the circuit board 70, and the third polishing is to polish the surface semi-cured sheet 710 to make the surface flat, forming a circuit board 80 with a high surface flatness, thereby improving the protection effect of the surface circuits, effectively preventing problems such as circuit bumps and oxidation, and avoiding problems such as the solder mask layer being recessed and the solder mask layer covering the surface circuits, which affects the use of the surface circuits.

[0083] In one embodiment (not shown in the drawings), resin ink is screen-printed on the surface of the circuit pattern board 70 and dried, and then a third polishing is performed to form a high-shielding embedded copper block circuit board 80; resin ink is used instead of the surface semi-cured sheet 710 to form an "embedded" surface circuit setting, and the resin ink can be screen-printed more accurately according to the distribution of the gaps between the surface circuit patterns, making the third polishing process easier and improving the processing accuracy.

[0084] It is worth noting that the surface circuit pattern 620 can be treated with immersion gold, electroplated gold, immersion tin, etc. to form a corrosion-resistant protective layer on the surface.

[0085] 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 transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a high-shielding embedded copper block circuit board, characterized in that: S10: taking a copper block and processing it into a U-shaped copper block with a through-groove structure; S20: taking a prepreg and making a prepreg window pattern to form a windowed prepreg, wherein the prepreg window pattern corresponds to the side wall top surface pattern of the U-shaped copper block; S30: Take a single-sided copper clad laminate, form a first circuit pattern on its copper layer, and form a core board window pattern corresponding to the prepreg window pattern on its insulating dielectric layer to form a first core board; S40: Take a double-sided copper-clad laminate and form a second circuit pattern on one copper layer of the laminate to form a second core board; S50: stacking the windowed prepreg, the first core board, the U-shaped copper block, and the second core board in order from top to bottom to form a stacked structure, and pressing them together to form a pressed board; The insulating dielectric layer of the first core board faces the through-groove structure of the U-shaped copper block, and the second circuit pattern of the second core board faces the bottom surface of the U-shaped copper block; The prepreg window pattern, the core board window pattern and the top surface of the side wall of the U-shaped copper block are stacked correspondingly; One side of the prepreg of the pressing plate is an upper surface, and the other side is a lower surface; S60: performing a first grinding on the upper surface to expose the sidewall top surface of the U-shaped copper block, then performing a first electroplating to form a first electroplated copper layer, and then performing a second grinding and a second electroplating process to form an electroplated plate; S70: forming a surface circuit pattern on the surface copper layer of the electroplating board to form a circuit pattern board; S80: pressing a surface prepreg onto the surface of the circuit pattern board, and then performing a third polishing to form the high-shielding embedded copper block circuit board.

2. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1, wherein: The top surface of the side wall of the U-shaped copper block is a serrated edge.

3. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 2, wherein: The first grinding is to completely grind the serrated edge.

4. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1 or 2, wherein: The outer surface of the U-shaped copper block is a continuous concave-convex pattern.

5. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1, wherein: The stacked structure includes: A first release film, a laminating film, a second release film and a first steel plate are sequentially arranged on the windowed prepreg to form an upper surface auxiliary pressing structure; A third release film and a second steel plate are sequentially arranged under the second core plate to form a lower surface auxiliary pressing structure.

6. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1, wherein: The first electroplating is to electroplating the upper surface.

7. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1 or 6, characterized in that: The thickness of the copper layer electroplated for the first time is 15 microns to 20 microns.

8. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1, wherein: The second electroplating is whole-plate electroplating.

9. The method for manufacturing a high-shielding embedded copper block circuit board according to claim 1, wherein: The second polishing is for polishing the first electroplated copper layer, and the third polishing is for polishing the surface prepreg.

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