A filled adhesive type double-sided high-frequency high-heat dissipation embedded metal base PCB manufacturing process

Abstract

The application relates to a filling glue type double-sided high-frequency high-heat-dissipation embedded metal base PCB manufacturing process, which is a method for embedding copper blocks into copper block embedding grooves on a core plate, fixing the copper blocks in the copper block embedding grooves on the core plate by resin hole plugging twice, wherein the core plate is a double-sided copper-clad plate, resin hole plugging is performed twice, including first resin hole plugging and second resin hole plugging, the first resin hole plugging is used for hole plugging between the short side of the copper block and the copper block embedding groove, after the first resin hole plugging is completed, the core plate is turned over, and the second resin hole plugging is performed from the back side, and the second resin hole plugging is used for hole plugging between the long side of the copper block and the copper block embedding groove. The PCB prepared by the filling glue type double-sided high-frequency high-heat-dissipation embedded metal base PCB manufacturing process can be applied to 5G communication products, solves the heat dissipation problem after the upgrade of the attack and release channels, and has the advantages of full hole plugging, high product reliability, long service life and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of PCB manufacturing, in particular to a filling glue type double-sided high-frequency high-heat-dissipation embedded metal base PCB manufacturing process. BACKGROUND

[0002] With the rapid development of the 5G communication field, PCB products are also continuously upgraded, and the requirements for reliability and heat dissipation are higher and higher, and products also develop towards integration, at present, the modules used in the whole communication base station are composed of a PCB mother board and a daughter board, the material used in the mother board is a high-speed material, and the material used in the daughter board is a high-frequency material, which is equivalent to packaging and mounting two materials with different performances, the daughter board requires high heat dissipation, high flatness and high signal transmission, and the current daughter board adopts a dense hole mode to meet the heat dissipation requirement, but with the upgrading of the next generation of communication base station, the signal transmission of the daughter board is compressed from 24 channels to 16 channels, and the packaging size is smaller, which means that the original dense hole cannot replace heat dissipation to meet the requirement. SUMMARY

[0003] The application provides a filling glue type double-sided high-frequency high-heat-dissipation embedded metal base PCB manufacturing process applied to 5G communication products, which solves the heat dissipation problem after the upgrade of the attack and release channels and has the advantages of high product reliability, long service life and the like.

[0004] In order to achieve the above-mentioned purpose, the following technical scheme is adopted.

[0005] The application provides a filling glue type double-sided high-frequency high-heat-dissipation embedded metal base PCB manufacturing process, which comprises the following steps: first, a copper block groove is manufactured on a core plate; then, a copper block is embedded in the copper block groove; and finally, the copper block is fixed in the copper block groove on the core plate by twice resin hole plugging, wherein the core plate is a double-sided copper-clad plate. The application adopts the method of twice resin hole plugging for fixing the copper block, first manufactures the copper block groove on the core plate, then embeds and fixes the copper block in the copper block groove, embeds and fixes the copper block on the double-sided copper-clad plate, realizes the manufacturing method of embedding copper on the double-sided plate, effectively solves the heat dissipation problem of the core plate, effectively avoids the problem of large packaging size of the embedded copper in the multilayer plate in the prior art, and has the advantages of small PCB packaging size, high product reliability, long service life and the like.

[0006] Further, the manufacturing process comprises, core plate cutting → copper block slotting → copper block inlaying → first resin hole plugging → AOI scanning → second drilling → electroplating → Via resin hole plugging → secondary electroplating → outer dry film → pattern electroplating → third drilling → alkaline etching → outer AOI, wherein, the copper block is made before the copper block inlaying; the resin hole plugging is performed twice, including first resin hole plugging and second resin hole plugging, the first resin hole plugging is used for plugging between the short side of the copper block and the copper block slotting, and after the first resin hole plugging is completed, the core plate is turned over, and the second resin hole plugging is performed from the back, and the second resin hole plugging is used for plugging between the long side of the copper block and the copper block slotting.

[0007] In the manufacturing process, the first resin hole plugging is performed on the position corresponding to the short side of the copper block, and after the short side plugging is completed, the second resin hole plugging is performed on the position corresponding to the long side of the copper block from the back, that is, the long side plugging of the copper block is performed, and the plugging method effectively ensures that the plugging is full, avoids the problem of incomplete and insufficient plugging in the prior art, and effectively ensures the product quality.

[0008] Further, the manufacturing process comprises,

[0009] A plurality of small holes are drilled around the position of the copper block on the core plate by using a drilling device as plugging oil points, the small holes cut into the copper block position by a certain distance, and gaps are left between adjacent small holes;

[0010] A plurality of large holes are drilled by using a drilling device, the large holes have an outer diameter exceeding the copper block position by a certain distance, and the small holes form half holes after the large hole drilling is completed, and the buried copper block slot with a plurality of half hole-shaped slot edges is obtained.

[0011] In the manufacturing of the buried copper block slot, a plurality of small holes are first drilled around the copper block, the small holes form gaps between the core plate and the copper block, and are used as oil points when plugging, that is, the glue filling space, so that the copper block and the core plate are fixed firmly after plugging; the gaps between adjacent small holes form a wave-shaped recess on the wall of the buried copper block slot, and further form a wave-shaped structure when the glue is filled, which further ensures that the glue is full and the copper block is fixed well; after a plurality of small holes with gaps are drilled, a large drill bit is used to continuously drill a plurality of large holes, and the drilling of the plurality of large holes removes the material in the center of the buried copper block slot, realizes the drilling of the buried copper block slot, and further forms a wave-shaped recess hole by a plurality of half holes, which ensures the glue filling quality and effect.

[0012] Further, the aperture of the through hole is 0.25mm, and the large hole is drilled by using a 1.0mm drill bit. The through hole aperture is set to 0.25mm, so that when the hole is filled with glue, the glue can smoothly enter and the adjacent through holes can be connected together, effectively ensuring the quality of the hole filling. The large hole is drilled by using a 1.0mm drill bit in a silkworm method, so that multiple large holes overlap each other, on the one hand, the copper block slot is drilled, and on the other hand, multiple small holes form a half-hole structure, finally realizing that the overall shape of the copper block slot is rectangular, and the rectangular margin is in a wave shape, which provides a guarantee for the quality of the resin hole filling.

[0013] Further, the copper block slot is 2-6mil larger than the copper block size, and the small hole aperture is cut into the copper block by 2mil. The size of the copper block slot is overall larger than the size of the copper block, and the small hole aperture is cut into the copper block by 2mil, on the one hand, after the copper block is embedded in the copper block slot, a filling gap is formed between the side wall of the copper block and the wall of the copper block slot, on the other hand, after the large hole is drilled, the small hole forms a half-hole, and then multiple small holes form a wave structure, and then the glue is more full when filling the hole, and the copper block is more stable.

[0014] Further, the copper block is provided with an annular groove around the periphery. In this embodiment, the annular groove around the periphery of the copper block is provided, so that after the copper block is embedded in the copper block slot and the resin hole filling is performed, the copper block and the resin form a "mortise and tenon structure", greatly enhancing the bonding force between the copper block and the resin, so that the copper block is fixed and stable after the hole filling, and is not easy to fall off, thereby effectively ensuring the product quality.

[0015] Further, the manufacturing process further includes a copper block fixing process, which is arranged before the vacuum resin hole filling. Before hole filling, the copper block is initially fixed in the core plate, and then the vacuum resin hole filling is performed for hole filling fixation, which can effectively avoid the influence of copper block shaking on hole filling and ensure the quality of hole filling.

[0016] Further, the copper block fixing process uses high-temperature adhesive paper to fix the copper block or uses release film to fix the copper block. During operation, high-temperature adhesive paper or release film can be selected according to actual conditions, and the operation and use are flexible and convenient.

[0017] Further, as one of the preferred schemes of the present application, the method for fixing the copper block by high-temperature adhesive paper is as follows: after the copper block is embedded into the copper block embedding groove, before the first resin hole filling, the long side of the copper block is first fixed on the core board by high-temperature adhesive paper to realize the initial fixing of the copper block. After the initial fixing of the copper block by high-temperature adhesive paper, the short side of the copper block is exposed, and the first resin hole filling is performed between the short side of the copper block and the copper block embedding groove to fill the gap between the short side of the copper block and the copper block embedding groove with resin. After the first resin hole filling and board baking, the copper block is fixed on the core board, the high-temperature adhesive paper is torn off, the core board is turned over, and the second resin hole filling and board baking are performed between the long side of the copper block and the copper block embedding groove from the back of the core board to completely fix the copper block on the core board.

[0018] Further, as the second preferred scheme of the present application, the method for fixing the copper block by release film is as follows: a release film is first fixed on the back of the core board at a position corresponding to the long side of the copper block, then the copper block is embedded into the copper block embedding groove from the front of the core board, and then a release film is fixed on the front of the core board at a position corresponding to the long side of the copper block to realize the initial fixing of the copper block. After the initial fixing of the copper block by release film, the short side of the copper block is exposed, and the first resin hole filling is performed between the short side of the copper block and the copper block embedding groove to fill the gap between the short side of the copper block and the copper block embedding groove with resin. After the first resin hole filling and board baking, the copper block is fixed on the core board, the release films on the two sides of the core board are torn off, the core board is turned over, and the second resin hole filling and board baking are performed between the long side of the copper block and the copper block embedding groove from the back of the core board to completely fix the copper block on the core board.

[0019] Compared with the prior art, the manufacturing process of the glue-filled double-sided high-frequency high-heat-dissipation metal-embedded PCB has the following beneficial effects: the copper block is fixed by twice resin hole filling in the present application, the copper block embedding groove is first made on the core board, and then the copper block is embedded into the copper block embedding groove for fixing, so that the copper block is embedded and fixed on the double-sided copper-clad plate, the manufacturing method of embedding copper on the double-sided plate is realized, the heat dissipation problem of the core board is effectively solved, the problem of large packaging size in the prior art is effectively avoided, the packaging size of the PCB manufactured by the present application is small, the present application is applied to 5G communication products, the heat dissipation problem after the upgrade of the attack and play channel is solved, and the present application has the advantages of high product reliability, long service life and the like. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The manufacturing process of the glue-filled double-sided high-frequency high-heat-dissipation metal-embedded PCB of the present application is shown in the following figure;

[0021] Figure 2 The Figure 1 structure diagram of the copper block;

[0022] Figure 3 The Figure 1 top view;

[0023] Figure 4 isFigure 3 A part of enlarged view in Fig. 1. DETAILED DESCRIPTION

[0024] The filling glue type double-sided high-frequency high-heat dissipation buried metal base PCB manufacturing process will be further described in detail below in combination with specific embodiments and drawings.

[0025] Referring to Figures 1 to 4 , in a non-limiting embodiment of the present application, a filling glue type double-sided high-frequency high-heat dissipation buried metal base PCB manufacturing process, the manufacturing process is a method of first manufacturing a buried copper block groove 13 on a core plate 10, embedding a copper block 20 into the buried copper block groove 13, and then fixing the copper block 20 in the buried copper block groove 13 on the core plate 10 by resin plugging twice, wherein the core plate 10 is a double-sided copper-clad plate, including a core plate body 11 and a copper-clad layer 12 covered on the upper and lower surfaces of the core plate body 11. Specifically, in this embodiment, the manufacturing process includes core plate 10 cutting → buried copper block groove 13 → inlaying copper block 20 → vacuum resin plugging → AOI scanning → second drilling → electroplating → Via resin plugging → secondary electroplating → outer layer dry film → pattern electroplating → third drilling → alkaline etching → outer layer AOI, wherein the manufacturing of the copper block 20 is completed before inlaying the copper block 20; the resin plugging is performed twice, including first resin plugging and second resin plugging, the first resin plugging is used for plugging between the short side of the copper block 20 and the buried copper block groove 13, and after the first resin plugging is completed, the core plate 10 is turned over, and the second resin plugging is performed from the reverse side, and the second resin plugging is used for plugging between the long side of the copper block 20 and the buried copper block groove 13. The present application adopts the method of fixing the copper block 20 by resin plugging twice, first manufacturing the buried copper block groove 13 on the core plate 10, then embedding and fixing the copper block 20 after embedding the copper block 20 into the buried copper block groove 13, so that the copper block 20 is embedded and fixed on the double-sided copper-clad plate, realizing the manufacturing method of burying copper on the double-sided plate, effectively solving the heat dissipation problem of the core plate 10, effectively avoiding the problem of large packaging size of copper buried in the multi-layer plate in the prior art, the PCB packaging size manufactured by the present application is small, and is used in 5G communication products, solving the heat dissipation problem after the attack and release channel is upgraded, and having the advantages of high product reliability, long service life and the like. Specifically, in the manufacturing process of the present application, the first resin plugging is performed at the position corresponding to the short side of the copper block 20, after the short side plugging is completed, the second resin plugging is performed at the position corresponding to the long side of the copper block 20 from the reverse side, that is, the long side plugging of the copper block 20 is performed. This plugging method effectively ensures that the plugging is full, avoids the problem of incomplete and insufficient plugging of the long side in the prior art, and effectively ensures the product quality.

[0026] Referring to Figures 1 to 4 , in a non-limiting embodiment of the present application, the manufacturing of the buried copper block groove 13 includes,

[0027] A plurality of small holes 131 are drilled around the position of the copper block 20 on the core plate 10 by a drilling device as oil injection points for the plug, the holes 131 cut into the copper block 20 position a distance, and a gap is left between adjacent holes 131; during the manufacture of the copper block slot 13, a plurality of small holes 131 are first drilled around the copper block 20, the hole 131 forms a gap between the core plate 10 and the copper block 20, which is used as an oil injection point when the plug is filled, that is, the glue filling space, so that the copper block 20 and the core plate 10 are fixed firmly after the plug; the gap between adjacent holes 131 allows the wall of the copper block slot 13 to form a wavy recess, and further allows the glue to form a wavy structure when the plug is filled, which further ensures that the glue is full and the copper block 20 is fixed well.

[0028] A plurality of large holes 132 are drilled by a drilling device, the large holes 132 have an outer diameter that exceeds the copper block 20 position by a certain distance, and the small holes form a half hole after the large hole 132 is drilled, and the copper block slot 13 with a plurality of half hole-shaped slot edges is obtained; after a plurality of holes 131 with gaps are drilled, a large drill bit is used to continuously drill a plurality of large holes 132, the drilling of a plurality of large holes 132, on the one hand, removes the center plate of the copper block slot 13, achieving the drilling of the copper block slot 13, on the other hand, the plurality of small holes 131 form a half hole structure, and further the plurality of half holes form a wavy recess, ensuring the quality and effect of the glue filling.

[0029] Referring to Figures 1 to 4 , in a non-limiting embodiment of the present application, the hole diameter of the hole 131 is 0.25 mm, and the large hole 132 is drilled by a 1.0 mm drill bit. The hole diameter of the hole 131 is set to 0.25 mm, which can ensure that the glue enters smoothly and the adjacent holes 131 are glued together when the plug is filled, effectively ensuring the quality of the plug; the large hole 132 is drilled by a 1.0 mm drill bit in a silk method, so that a plurality of large holes 132 overlap each other, on the one hand, the copper block slot 13 is drilled, on the other hand, a plurality of small holes form a half hole structure, and finally the overall shape of the copper block slot 13 is rectangular, and the rectangular edge distance is wavy, which provides a guarantee for the quality of the resin plug.

[0030] Referring to Figures 1 to 4 , in a non-limiting embodiment of the present application, the copper block slot 13 is 2-6 mil larger than the size of the copper block 20, and the small hole diameter cuts into the copper block 202 mil. The size of the copper block slot 13 is larger than the size of the copper block 20, and the small hole diameter cuts into the copper block 202 mil, on the one hand, the copper block 20 forms a filling gap between the side wall of the copper block 20 and the wall of the copper block slot 13 after being embedded in the copper block slot 13, on the other hand, the small hole forms a half hole after the large hole 132 is drilled, and further the plurality of small holes form a wavy structure, and further the glue is more full when the plug is filled, and the copper block 20 is more stable.

[0031] With reference to Figures 1 to 4 In a non-restrictive embodiment of the present application, the copper block 20 is provided with a ring-shaped groove 21 around the periphery. In this embodiment, the ring-shaped groove 21 around the periphery of the copper block 20 enables the copper block 20 to form a "mortise and tenon structure" with the resin 30 after the copper block 20 is embedded in the copper block slot 13 and resin hole filling is performed, greatly enhancing the bonding force between the copper block 20 and the resin, so that the copper block 20 is fixed and stable after hole filling and is not easy to fall off, thereby effectively ensuring product quality.

[0032] With reference to Figures 1 to 4 In a non-restrictive embodiment of the present application, the manufacturing process further includes a copper block 20 fixing process. The copper block 20 fixing process is arranged before the vacuum resin hole filling. Before hole filling, the copper block 20 is initially fixed in the core plate 10, and then vacuum resin hole filling is performed for hole filling fixation, which can effectively avoid the influence of copper block 20 shaking on hole filling and ensure hole filling quality.

[0033] With reference to Figures 1 to 4 In a non-restrictive embodiment of the present application, the copper block 20 fixing process uses high-temperature adhesive paper to fix the copper block 20 or uses a release film to fix the copper block 20. During operation, high-temperature adhesive paper fixing or release film fixing can be selected according to actual conditions, and operation and use are flexible and convenient.

[0034] With reference to Figures 1 to 4 In a non-restrictive embodiment of the present application, as one of the preferred schemes of the present application, the method for fixing the copper block 20 by high-temperature adhesive paper is as follows. After the copper block 20 is embedded in the copper block slot, before the first resin hole filling, high-temperature adhesive paper is used to fix the long side of the copper block 20 to the core plate 10, so as to initially fix the copper block 20. After the copper block 20 is initially fixed by high-temperature adhesive paper, the short side of the copper block 20 is exposed, and the first resin hole filling is performed between the short side of the copper block 20 and the copper block slot 13, so that the resin fills the gap between the short side of the copper block 20 and the copper block slot 13. After the first resin hole filling and plate baking, the copper block 20 is fixed to the core plate 10, the high-temperature adhesive paper is torn off, the core plate 10 is turned over, and the second resin hole filling and plate baking are performed on the long side of the copper block 20 and the copper block slot 13 from the back of the core plate 10, so as to completely fix the copper block 20 to the core plate 10.

[0035] With reference to Figures 1 to 4In a non-limiting embodiment of the present application, in addition to the above-mentioned fixing of the copper block 20 by using high-temperature adhesive paper, a release film can also be used to fix the copper block 20. Specifically, in this embodiment, the method for fixing the copper block 20 by using a release film is as follows: first, a release film is fixed on the back surface of the core plate 10 at a position corresponding to the long side of the copper block 20; then, the copper block 20 is embedded into the copper block embedding groove from the front surface of the core plate 10; and then, a release film is fixed on the front surface of the core plate 10 at a position corresponding to the long side of the copper block 20, thereby completing the initial fixing of the copper block 20. After the initial fixing of the copper block 20 by using the release film, the short side of the copper block 20 is exposed, and the first resin hole filling is performed between the short side of the copper block 20 and the copper block embedding groove 13, so that the resin fills the gap between the short side of the copper block 20 and the copper block embedding groove 13. After the first resin hole filling and baking, the copper block 20 is fixed on the core plate 10, the release films on the two surfaces of the core plate 10 are torn off, the core plate 10 is turned over, and the second resin hole filling and baking are performed between the long side of the copper block 20 and the copper block embedding groove 13 from the back surface of the core plate 10, thereby completely fixing the copper block 20 on the core plate 10.

[0036] Reference Figures 1 to 4 In a non-limiting embodiment of the present application, compared with the prior art, the filling adhesive type double-sided high-frequency high-heat dissipation metal embedded PCB manufacturing process has the following beneficial effects: the method for fixing the copper block 20 by using the present application is performed in two times of resin hole filling, the copper block embedding groove 13 is first manufactured on the core plate 10, and then the copper block 20 is embedded into the copper block embedding groove 13 and fixed, so that the copper block 20 is embedded and fixed on the double-sided copper-clad plate, the manufacturing method for embedding copper on the double-sided plate is realized, the heat dissipation problem of the core plate 10 is effectively solved, the problem of large packaging size in the prior art is effectively avoided, the packaging size of the PCB manufactured by using the present application is small, the present application is used in 5G communication products, the heat dissipation problem after the upgrade of the attack and transmission channel is solved, and the present application has the advantages of high product reliability, long service life, etc.

[0037] The above-mentioned embodiments are only specific embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, and these obvious alternative forms all belong to the protection scope of the present application.

Claims

1. A filling-type double-sided high-frequency high-heat-dissipation embedded metal-based PCB manufacturing process, characterized in that: The manufacturing process involves first creating a copper block groove on the core board, embedding the copper block into the copper block groove, and then fixing the copper block in the copper block groove on the core board by sealing the holes with resin in two stages. The core board is a double-sided copper-clad laminate. The manufacturing process includes: core board cutting → copper block embedding groove → copper block embedding → vacuum resin plugging → AOI scanning → second drilling → electroplating → Via resin plugging → second electroplating → outer dry film → pattern electroplating → third drilling → alkaline etching → outer AOI. The copper blocks are fabricated before embedding. Resin plugging is performed in two stages: a first resin plugging and a second resin plugging. The first resin plugging is used to plug the short side of the copper block between the copper block and the embedding groove. After the first resin plugging, the core board is flipped over, and the second resin plugging is performed from the reverse side. The second resin plugging is used to plug the long side of the copper block between the embedding groove.

2. The filling-type double-sided high-frequency high-heat dissipation embedded metal substrate PCB manufacturing process according to claim 1, characterized in that: The fabrication of the copper block groove includes: drilling multiple small through holes around the location where the copper block is embedded in the core board using a drilling machine as plugging points; the through holes are inserted into the copper block location at a certain distance, and gaps are left between adjacent through holes; drilling multiple overlapping large holes using a drilling machine; the outer diameter of the large holes exceeds the location of the copper block at a certain distance; the through holes form half holes after the large holes are drilled, resulting in a copper block groove with multiple half holes on the side.

3. The filling-type double-sided high-frequency high-heat dissipation embedded metal substrate PCB manufacturing process according to claim 2, characterized in that: The diameter of the through hole is 0.25 mm, and the large hole is drilled using a 1.0 mm drill bit.

4. The filling-type double-sided high-frequency high-heat dissipation embedded metal substrate PCB manufacturing process according to claim 3, characterized in that: The copper block groove is 2-6 mil larger than the copper block, and the through hole diameter cuts into the copper block by 2 mil.

5. The filler-type double-sided high-frequency high-heat-dissipation embedded metal substrate PCB manufacturing process according to any one of claims 1 to 4, characterized in that: The copper block has an annular groove around its perimeter.

6. The filling-type double-sided high-frequency high-heat-dissipation embedded metal substrate PCB manufacturing process according to claim 5, characterized in that: The manufacturing process also includes a copper block fixing process.

7. The filling-type double-sided high-frequency high-heat-dissipation embedded metal substrate PCB manufacturing process according to claim 6, characterized in that: The copper block fixing process uses high-temperature adhesive tape or release film to fix the copper block.

8. The filling-type double-sided high-frequency high-heat-dissipation embedded metal substrate PCB manufacturing process according to claim 7, characterized in that: The method for fixing the copper block with high-temperature adhesive tape is as follows: After the copper block is embedded in the copper embedding groove, before the first resin plugging, the long side of the copper block is first attached to and fixed to the core board with high-temperature adhesive tape to achieve initial fixation of the copper block. After the copper block is initially fixed with high-temperature adhesive tape, the short side of the copper block is exposed. The short side of the copper block and the copper embedding groove are plugged with resin for the first time, so that the resin fills the gap between the short side of the copper block and the copper embedding groove. After the first resin plugging and baking, the copper block is fixed to the core board. The high-temperature adhesive tape is then removed, the core board is flipped over, and the long side of the copper block and the copper embedding groove are plugged with resin and baked for the second time from the back of the core board to completely fix the copper block to the core board.

9. The filling-type double-sided high-frequency high-heat-dissipation embedded metal substrate PCB manufacturing process according to claim 7, characterized in that: The method for fixing the copper block with the release film is as follows: First, a release film is fixed on the back of the core board at a position corresponding to the long side of the copper block. Then, the copper block is embedded into the copper embedding groove from the front of the core board. Another release film is then fixed on the front of the core board at a position corresponding to the long side of the copper block to complete the initial fixation of the copper block. After the release film initially fixes the copper block, the short side of the copper block is exposed. The short side of the copper block and the copper embedding groove are then filled with resin for the first time, so that the resin fills the gap between the short side of the copper block and the copper embedding groove. After the first resin filling and baking, the copper block is fixed on the core board. The release films on both sides of the core board are then removed, the core board is flipped over, and the long side of the copper block and the copper embedding groove are filled with resin for the second time from the back of the core board. The copper block is then completely fixed on the core board.

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