Copper substrate embedding method of separated special-shaped copper block and circuit board

Abstract

The invention relates to a copper substrate embedding method for separated special-shaped copper blocks and a circuit board, and the method comprises the following steps: processing a plurality of special-shaped copper blocks with preset shapes on a copper plate, and reserving a plurality of connecting ribs which are not completely cut off between the adjacent special-shaped copper blocks; a gap between every two adjacent special-shaped copper blocks is filled with resin; a heat-conducting insulating layer and a copper foil are sequentially overlaid on the two opposite faces of the copper plate to form a stacked structure, and a substrate is formed through high-temperature pressing; an isolation groove is formed in the position, corresponding to the connecting rib, of the substrate, and the isolation groove cuts off the connecting rib; the isolation groove is filled with resin, and the resin overflowing out of the plate surface is rubbed down; and conducting treatment: forming a continuous conductive copper layer on the surface of the resin filling area. According to the invention, no copper groove needs to be buried, the copper block can be processed into a specific shape, and the distance between two adjacent special-shaped copper blocks is controlled to be 1.0 mm, so that the number and the area of the copper blocks buried in the substrate are greatly increased, and the heat dissipation performance and the electrical performance of the circuit board are improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards, and in particular to a method for embedding separate special-shaped copper blocks into a copper substrate and a circuit board. Background Art

[0002] The buried copper circuit board is a circuit board manufacturing technology that embeds copper blocks inside a multi-layer PCB. The core of the technology is to tightly combine the copper blocks with the outer layer of epoxy resin to form a flat and highly thermally conductive structure. In related technologies, the method of burying copper blocks is usually to mill out buried copper grooves on the inner core board and the PP sheet (semi-cured sheet). The size of the buried copper grooves needs to be precisely controlled to ensure that they can match the buried copper blocks, and then they are pressed together to form a buried copper circuit board. In the actual processing process, it was found that the existing method of burying copper blocks has high processing requirements for the buried copper grooves. The spacing between adjacent copper blocks needs to be greater than 4mm to ensure that the inner core board will not be deformed. At the same time, there are certain restrictions on the shape of the copper blocks, which are usually regular blocks. Therefore, the space utilization rate of the core board is low, the size and number of the buried copper blocks are small, and the copper blocks cannot play a good role. Summary of the Invention

[0003] In view of this, the present invention provides a method for embedding separate special-shaped copper blocks in a copper substrate, which can increase the area of ​​the copper blocks embedded in the circuit board.

[0004] The purpose of the present invention is achieved through the following technical solutions: In one aspect, the present invention provides a method for embedding a separate special-shaped copper block into a copper substrate, comprising the following steps: S1. Copper plate forming: processing a plurality of special-shaped copper blocks of a preset shape on the copper plate, leaving a plurality of spaced and uncut connecting ribs between adjacent special-shaped copper blocks; S2, copper plate reinforcement: using resin to fill the gap between two adjacent special-shaped copper blocks; S3, substrate forming: stacking a thermally conductive insulating layer and a copper foil on two opposite sides of the copper plate to form a laminated structure, and then pressing the laminated structure at a high temperature to form a substrate; S4, substrate slotting: forming an isolation slot on the substrate at a position corresponding to the connecting rib, wherein the isolation slot extends along the thickness direction of the substrate to cut off the connecting rib; S5, substrate repair: fill the isolation groove with resin and smooth out the resin that overflows the board surface; S6. Conductive treatment: performing chemical copper deposition treatment on the repaired substrate surface to form a continuous conductive copper layer on the surface of the resin-filled area.

[0005] In the above technical solution, when burying the copper substrate, the present invention first processes the copper plate into a plurality of preset special-shaped copper blocks to better match the outer layer circuits and electronic components. The copper plate retains some connecting ribs and fills the gaps with resin, so that the copper plate can maintain strength and facilitate subsequent pressing with the thermal insulation layer and copper foil. After pressing, the connecting ribs are removed to separate the various special-shaped copper blocks from each other. Finally, the resin is filled and the copper layer is plated to achieve the embedding of the special-shaped copper blocks. Compared with the traditional method of first embedding copper grooves on the substrate and then embedding copper blocks and pressing them, the present invention does not require embedding copper grooves, so the shape of the copper blocks and the gap setting between the copper blocks can be more flexible. The copper blocks can be processed into specific shapes according to the actual circuit layout, and the spacing between two adjacent special-shaped copper blocks can be controlled to 1.0 mm, which is much smaller than the traditional 4.0 mm. This can greatly increase the number and area of ​​copper blocks embedded in the substrate, effectively improving the heat dissipation performance and electrical performance of the circuit board.

[0006] Optionally, in a possible implementation, in step S2, before filling the gaps, a protective film is first affixed to one side of the copper plate to seal all gaps, and then resin is filled from the other side opposite to the copper plate.

[0007] In this technical solution, by applying a protective film to one side of the copper plate to seal all gaps and then filling the resin from the opposite side, the resin can be precisely filled into the gaps between the shaped copper blocks. This effectively prevents resin from overflowing into unwanted areas, improves the accuracy of the resin filling, and ensures that each gap is evenly filled, thereby better strengthening the copper plate and preventing problems such as warping or deformation during lamination.

[0008] Optionally, in a possible implementation, in step S2, after the gap is filled, the resin overflowing the gap is polished off to keep the surface of the copper plate flat.

[0009] In this technical solution, the flat copper plate surface improves the quality of subsequent lamination, preventing gaps between layers or poor lamination caused by resin overflow or unevenness, thereby improving the quality of the laminated structure. Furthermore, the flat copper plate surface facilitates uniform heat conduction, thereby improving the heat dissipation efficiency of the entire substrate.

[0010] Optionally, in a possible implementation, in step S4, when processing the isolation trench, the isolation trench is extended along the thickness direction of the substrate until it penetrates the substrate.

[0011] In this technical solution, by inserting isolation grooves through the substrate, complete electrical isolation is achieved between adjacent special-shaped copper blocks, effectively preventing interference between circuits and improving circuit stability and reliability. This also creates a more regular heat conduction path on the substrate, helping to distribute heat more evenly across the entire substrate, avoiding localized overheating and thus extending the life of the device.

[0012] Optionally, in a possible implementation, in step S5, before filling the isolation grooves, a protective film is first attached to one side of the substrate to close all the isolation grooves, and then the resin is filled from the other side opposite to the substrate.

[0013] In this technical solution, the protective film ensures precise resin filling into the isolation slots. Because the isolation slots are sealed by the protective film, resin can only flow in a predetermined direction, preventing it from flowing into unwanted areas during the filling process. This improves filling accuracy, ensures that each isolation slot is fully and evenly filled, and reduces resin waste.

[0014] Optionally, in a possible implementation, the thermally conductive insulating layer is a prepreg or an FR4 composite material.

[0015] In the above technical solution, both the prepreg and FR4 composite material possess excellent insulation properties. As thermally conductive insulation layers, they effectively isolate conductive components such as copper blocks and copper foil, preventing short circuits between circuits. Furthermore, both possess a certain degree of thermal conductivity, allowing heat generated by electronic components to be effectively transferred to heat dissipation structures such as copper foil and special-shaped copper blocks, thereby promoting heat dissipation throughout the substrate.

[0016] Optionally, in a possible implementation, the length of the connecting rib is 2.0-4.0 mm, and the width of the isolation groove is 1.0-4.0 mm.

[0017] In the above technical solution, the appropriate width of the connecting rib can provide sufficient connection strength while reducing the workload of cutting the groove in the later stage. The isolation groove width is within the appropriate range, which can ensure the electrical isolation of adjacent special-shaped copper blocks while not excessively weakening the overall structural strength of the substrate.

[0018] Optionally, in a possible implementation, the thickness of the connecting rib is smaller than the thickness of the special-shaped copper block, and a step structure is formed between the connecting rib and the special-shaped copper block.

[0019] In the above technical solution, the stepped structure formed between the connecting rib and the special-shaped copper block can effectively improve the structural strength of the filling resin and prevent the resin around the connecting rib from falling off during subsequent grooving, thereby further improving the structural strength of the substrate. At the same time, because the thickness of the connecting rib is thinner, it is less likely to affect the special-shaped copper block when the connecting rib falls off.

[0020] Optionally, in a possible implementation, one end of the connecting rib connected to the special-shaped copper block extends into the interior of the special-shaped copper block, and the extension length is 0.5-1.0 mm.

[0021] In the above technical solution, the connecting ribs extending into the interior of the special-shaped copper block form a groove on the special-shaped copper block, and the resin can be filled into the groove to form a mosaic structure, which can further improve the structural strength of the resin and prevent it from falling off.

[0022] On the other hand, the present invention further provides a circuit board comprising the copper substrate as described in any one of the above items.

[0023] In the above technical solution, the circuit board made by using the above copper substrate has better heat dissipation performance, electrical performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 Schematic diagram of the overall process of an embodiment.

[0026] Figure 2 Schematic diagram of the structure of a copper plate in one embodiment.

[0027] Figure numerals: 1-copper plate; 2-special-shaped copper block; 3-connecting rib; 4-gap. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0030] Please refer to Figure 1 This embodiment provides a method for embedding a separate special-shaped copper block 2 into a copper substrate, comprising the following steps: S1. Forming the copper plate 1: Using CNC milling equipment, a plurality of special-shaped copper blocks 2 of a preset shape are processed on the copper plate 1. The shape and size of each special-shaped copper block 2 are different and can be flexibly set according to the actual outer layer circuits and electronic components. A plurality of connecting ribs 3 that are not completely cut off are retained between adjacent special-shaped copper blocks 2; S2. Copper plate 1 reinforcement: Use thermosetting epoxy resin to fill the gap 4 between two adjacent special-shaped copper blocks 2 to form a structural reinforcement layer, restore the original structure of the copper plate 1 and separate the copper plate 1 into the special-shaped copper block 2 part and the resin part; S3, substrate forming: On the opposite sides of the reinforced copper plate 1, i.e., the upper and lower surfaces, a thermally conductive insulating layer and a copper foil are sequentially stacked to form a laminated structure, and then the laminated structure is subjected to high-temperature pressing and curing to form a substrate; wherein the high-temperature pressing conditions are 180-220°C and 8-12MPa pressure; S4, substrate slotting: using precision milling equipment to form isolation slots on the substrate at positions corresponding to the connecting ribs 3. The isolation slots extend along the thickness direction of the substrate to cut off the connecting ribs 3. S5. Substrate repair: Use resin to fill the isolation groove and grind off the resin that overflows the board surface; specifically, grind until the filling surface is flush with the substrate surface.

[0031] S6. Conductive treatment: Perform chemical copper deposition on the surface of the repaired substrate to form a continuous conductive copper layer on the surface of the resin-filled area.

[0032] In this embodiment, when embedding a copper substrate, the copper plate 1 is first processed into a plurality of pre-set special-shaped copper blocks 2 to better match the outer layer circuits and electronic components. The copper plate 1 retains some connecting ribs 3 and the removed gaps 4 are filled with resin to ensure that the copper plate 1 maintains its strength and facilitates subsequent lamination with the thermally conductive insulation layer and copper foil. After lamination, the connecting ribs 3 are removed to separate the various special-shaped copper blocks 2 from each other. Finally, the special-shaped copper blocks 2 are filled with resin and plated with a copper layer to achieve the embedding of the special-shaped copper blocks 2. Compared to the traditional method of first embedding copper grooves on the substrate and then embedding copper blocks and laminating them, this embodiment does not require embedding copper grooves. Therefore, there is no need to control the spacing between the embedded copper grooves to ensure the strength of the substrate. This allows for greater flexibility in the shape of the copper blocks and the setting of the gaps 4 between the copper blocks. The copper blocks can be processed into specific shapes according to the actual circuit layout, and the spacing between two adjacent special-shaped copper blocks 2 is controlled to 1.0 mm, which is much smaller than the traditional 4.0 mm. This can greatly increase the number and area of ​​copper blocks embedded in the substrate, effectively improving the heat dissipation and electrical performance of the circuit board.

[0033] In addition, the special-shaped copper blocks 2 processed in the copper plate 1 forming step (S1) can be designed according to specific heat dissipation requirements. These special-shaped copper blocks 2 form unique heat dissipation channels in the substrate, which helps to improve the efficiency of heat conduction. The provision of multiple special-shaped copper blocks 2 makes the heat distribution on the substrate more uniform, which can avoid local overheating. In the copper plate 1 reinforcement step (S2), the gaps 4 between adjacent special-shaped copper blocks 2 are filled with resin. This not only fixes the position of the special-shaped copper blocks 2, but also enhances the stability of the entire copper plate 1 structure to a certain extent. The resin-filled copper plate 1 can better maintain its shape and structural integrity during subsequent processing.

[0034] In step S2 of this embodiment, before filling the gaps 4, a protective film is first applied to one side of the copper plate 1 to seal all gaps 4, and then resin is filled from the opposite side of the copper plate 1. The protective film is a high-temperature adhesive applied to one side of the copper plate 1 and can be removed after the resin is filled and cured.

[0035] By applying a protective film to one side of the copper plate 1 to seal all gaps 4 and then filling the gaps 4 between the shaped copper blocks 2 with resin from the opposite side, the resin can be precisely filled into the gaps 4 between the shaped copper blocks 2. This effectively prevents resin from overflowing into unwanted areas, improves the accuracy of resin filling, and ensures that each gap 4 is evenly filled, thereby better strengthening the copper plate 1 and preventing problems such as warping or deformation during lamination.

[0036] In step S2 of this embodiment, after the gap 4 is filled, the resin overflowing from the gap 4 is polished off to keep the surface of the copper plate 1 flat. Specifically, the resin overflowing from the gap 4 can be polished by a polishing device, such as a belt resin grinder, so that the resin surface is flush with the surface of the special-shaped copper block 2.

[0037] The flat surface of the copper plate 1 improves the quality of subsequent lamination, preventing gaps between layers or poor lamination caused by bulges or unevenness caused by resin overflow, thereby improving the quality of the laminated structure. In addition, the flat surface of the copper plate 1 helps to evenly conduct heat, thereby improving the heat dissipation efficiency of the entire substrate.

[0038] In step S4 of this embodiment, the isolation grooves are formed so as to extend along the thickness of the substrate until they penetrate the substrate. By extending the isolation grooves through the substrate, complete electrical isolation can be achieved between adjacent special-shaped copper blocks 2, effectively preventing interference between circuits and improving circuit stability and reliability. This also makes the heat conduction path on the substrate more regular, helping to distribute heat more evenly across the substrate, avoiding local overheating and thus extending the service life of the device.

[0039] In step S5 of this embodiment, before filling the isolation trenches, a protective film is applied to one side of the substrate to seal all isolation trenches. Then, resin is applied to the opposite side of the substrate. The protective film is a high-temperature adhesive applied to one side of the substrate and can be removed after the resin has cured.

[0040] The protective film ensures precise resin filling into the isolation grooves. Because the isolation grooves are sealed by the protective film, resin can only flow in the designated direction, preventing it from flowing into unwanted areas during the filling process. This improves filling accuracy, ensures that each isolation groove is fully and evenly filled, and reduces resin waste. Furthermore, this step is identical to the resin filling of copper substrates and therefore offers the same advantages.

[0041] It should be noted that the thermally conductive insulating layer of this embodiment is a prepreg or FR4 composite material. Prepreg is abbreviated as PP, also known as film. It is formed by impregnating glass fiber cloth with epoxy resin and partially curing it at high temperature. Its components also include a hardener, an accelerator, a solvent, and a filler. The FR4 in FR4 composite material represents flame retardancy grade 4, a code name for the grade of flame-resistant material. It is a composite material with epoxy resin as the binder and glass fiber cloth as the reinforcing material.

[0042] Both prepreg and FR4 composite materials offer excellent insulation properties. As thermally conductive insulation layers, they effectively isolate conductive components like copper blocks and copper foil, preventing short circuits. They also possess a certain degree of thermal conductivity, allowing heat generated by electronic components to be effectively transferred to heat dissipation structures like copper foil and special-shaped copper blocks, helping to diffuse heat throughout the substrate.

[0043] In this embodiment, the length of the connecting rib 3 is 2.0-4.0 mm, and the width of the isolation groove is 1.0-4.0 mm. A suitable width of the connecting rib 3 provides sufficient connection strength while reducing the workload of later cutting the groove. Within a suitable range of isolation groove width, the substrate's overall structural strength is not significantly weakened while ensuring electrical isolation between adjacent special-shaped copper blocks 2.

[0044] It should be noted that the copper plate 1 needs to be super-roughened before filling with resin to prevent cracks between the resin and the copper base. Furthermore, if a large circular hole of approximately 10.0 mm is required on the copper plate 1 according to design requirements, the hole will not easily fill with resin. In this case, a 0.3-0.5 mm thick base material screen should be used to fill the resin and increase the amount of oil applied.

[0045] In this embodiment, the thickness of the connecting rib 3 is less than that of the special-shaped copper block 2, and a stepped structure is formed between the connecting rib 3 and the special-shaped copper block 2. In addition, the end of the connecting rib 3 connected to the special-shaped copper block 2 extends into the interior of the special-shaped copper block 2, and the extension length is 0.5-1.0 mm.

[0046] In the above technical solution, the stepped structure formed between the connecting rib 3 and the shaped copper block 2 can effectively improve the structural strength of the filled resin and prevent the resin around the connecting rib 3 from falling off during subsequent grooving, thereby further improving the structural strength of the substrate. At the same time, because the connecting rib 3 is thinner, it is less likely to affect the connected shaped copper block 2 when the connecting rib 3 falls off. The connecting rib 3 extending into the interior of the shaped copper block 2 forms a groove in the shaped copper block 2, which allows the resin to be filled into this groove, forming a chimeric structure, which further improves the structural strength of the resin and prevents it from falling off.

[0047] In addition, this embodiment further provides a circuit board, comprising the copper substrate as described above. It is understood that the circuit board made with the copper substrate has better heat dissipation performance, electrical performance and reliability.

[0048] In the description of the present invention, it should be understood that terms such as "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0049] Furthermore, the terms "first" and "second" are used 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 referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0050] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for embedding a separate special-shaped copper block into a copper substrate, characterized in that: The following steps are involved: S1. Copper plate forming: processing a plurality of special-shaped copper blocks of a preset shape on the copper plate, leaving a plurality of spaced and uncut connecting ribs between adjacent special-shaped copper blocks; S2. Copper plate reinforcement: using resin to fill the gap between two adjacent special-shaped copper blocks; S3, substrate forming: stacking a thermally conductive insulating layer and a copper foil on two opposite sides of the copper plate to form a laminated structure, and then pressing the laminated structure at a high temperature to form a substrate; S4, substrate slotting: forming an isolation slot on the substrate at a position corresponding to the connecting rib, wherein the isolation slot extends along the thickness direction of the substrate to cut off the connecting rib; S5, substrate repair: fill the isolation groove with resin and smooth out the resin that overflows the board surface; S6. Conductive treatment: performing chemical copper deposition treatment on the repaired substrate surface to form a continuous conductive copper layer on the surface of the resin-filled area.

2. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: In the step S2, before filling the gaps, a protective film is first applied to one side of the copper plate to seal all gaps, and then the resin is filled from the other side of the copper plate opposite to the other side.

3. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: In step S2, after the gap is filled, the resin overflowing the gap is polished off to keep the surface of the copper plate flat.

4. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: In the step S4 , when processing the isolation trench, the isolation trench is extended along the thickness direction of the substrate until it penetrates the substrate.

5. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 4, wherein: In the step S5 , before filling the isolation grooves, a protective film is first applied to one side of the substrate to seal all the isolation grooves, and then the resin is filled from the other side of the substrate opposite thereto.

6. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: The thermally conductive insulating layer is a prepreg or FR4 composite material.

7. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: The length of the connecting rib is 2.0-4.0 mm, and the width of the isolation groove is 1.0-4.0 mm.

8. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 1, wherein: The thickness of the connecting rib is smaller than that of the special-shaped copper block, and a step structure is formed between the connecting rib and the special-shaped copper block.

9. The method for embedding a separate special-shaped copper block into a copper substrate according to claim 8, wherein: One end of the connecting rib connected to the special-shaped copper block extends into the interior of the special-shaped copper block, and the extension length is 0.5-1.0 mm.

10. A circuit board, characterized in that: The invention comprises the copper substrate according to any one of claims 1 to 9.

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