Metal-based embedding method, metal-based circuit board and method for manufacturing the same

Abstract

The application belongs to the technical field of circuit board manufacturing, and particularly relates to a metal base embedding method, a metal base circuit board and a preparation method thereof. The metal base embedding method comprises the following steps: obtaining a dielectric layer plate and a core plate, machining a containing groove on the core plate, performing sidewall metallization on the groove wall of the containing groove, placing the dielectric layer plate between two core plates, placing a metal base in a metal base groove formed by the two containing grooves, and embedding the metal base into a multilayer plate formed by the two core plates through pressing. After the metal base is assembled, the metal base is directly attached to the electroplated layer of the groove wall to realize conduction. The electroplated copper of the through hole wall in the traditional process is replaced by the metal base to realize an electrical connection channel, a conductive channel arranged along the groove wall is constructed, the conductor conductive cross-sectional area is greatly increased, the overall current carrying capacity is effectively improved, and the use demand of the circuit board under a large current working condition is met.

Description

Technical Field

[0001] This invention belongs to the field of circuit board manufacturing technology, and in particular relates to a metal substrate embedding method, a metal substrate circuit board and its preparation method. Background Technology

[0002] Current metal-based PCB products integrate the metal substrate through slotting, embedding, and lamination, with a resin insulating layer between the metal substrate and the PCB. Due to structural limitations, the metal substrate and PCB can only be connected through an electroplated copper layer. This structure cannot carry large currents and cannot meet the performance requirements for high-current transmission. Summary of the Invention

[0003] The technical problem to be solved by this invention is: addressing the issue that existing metal substrates and PCBs can only be connected by directly electroplating a copper layer on the outer layer, which cannot carry large currents, this invention provides a metal substrate embedding method, a metal substrate circuit board, and a method for its fabrication.

[0004] To address the aforementioned technical problems, in one aspect, embodiments of the present invention provide a metal-based embedding method, comprising: Obtain a dielectric layer plate and a core plate, and machine a receiving groove on the core plate; The sidewalls of the receiving groove are metallized; The dielectric layer is placed between the two core plates, and the metal base is placed in the metal base groove formed by the connection of the two receiving grooves. By pressing, the metal base is embedded in the multilayer board formed by the two core plates.

[0005] Optionally, the receiving groove includes a first groove and a second groove that are interconnected; the process of obtaining the dielectric layer plate and the core plate, and machining the receiving groove on the core plate, includes: A first groove is machined inward from the first surface of the core board; A second groove is machined from the bottom of the first groove toward the second surface of the core plate; wherein the first surface and the second surface are arranged opposite to each other.

[0006] Optionally, the step of obtaining the dielectric layer and core plate, and machining a receiving groove on the core plate, further includes: A through groove is machined into the dielectric layer plate; The through groove is connected to the two receiving grooves to form the metal base groove.

[0007] Optionally, placing the dielectric layer between the two core plates, placing the metal substrate in a metal substrate groove formed by the two receiving grooves, and embedding the metal substrate into the multilayer board formed by the two core plates through pressing includes: The dielectric layer is stacked on the first core plate, and one end of the metal base is placed in the through groove and the receiving groove of the first core plate; The second core plate is fitted onto the metal base, and the other end of the metal base is placed in the receiving groove of the second core plate, wherein the two core plates are placed opposite each other.

[0008] Optionally, the sidewall metallization of the receiving groove includes: The sidewalls are metallized by a copper plating process, so that an electroplated layer is deposited on the first surface, the second surface, and the wall of the receiving tank.

[0009] Optionally, the sidewall metallization of the receiving groove includes: Patterned circuitry is performed on the first surface of the core board.

[0010] Optionally, the metal substrate includes a first substrate and a second substrate, the first substrate is disposed around the second substrate, the diameter of the first substrate is φ1, the diameter of the second substrate is φ2, and the thickness of the first substrate is h; The diameter of the first metallized groove is φ1, the depth of the first groove is h / 2, and the diameter of the second metallized groove is φ2.

[0011] Optionally, the metal base is copper-based, aluminum-based, or aluminum alloy-based.

[0012] On the other hand, embodiments of the present invention provide a method for preparing a metal-based circuit board, including the metal-based embedding method as described in any of the preceding claims; The method for preparing the metal-based circuit board further includes: At least one uplayer is laminated on the multilayer board, and metallized holes and patterned circuits are processed on the uplayer. Repeat the above steps until the target number of layers is reached to obtain a metal-based circuit board.

[0013] In another aspect, embodiments of the present invention provide a metal-based circuit board, which is prepared by the metal-based circuit board preparation method described above.

[0014] The metal substrate embedding method provided in this invention performs sidewall metallization on the receiving groove walls of two core boards. After the metal substrate is assembled, it is directly bonded to the electroplated layer of the groove wall to achieve conductivity. The metal substrate replaces the electroplated copper on the hole wall in the traditional process to realize the electrical connection path, constructs a conductive path arranged along the groove wall, significantly increases the conductor conductive cross-sectional area, effectively improves the overall current carrying capacity, and meets the requirements of high current operation of the circuit board. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of a metal-based embedding method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the metallization of the core board sidewalls according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a metal substrate provided in an embodiment of the present invention; Figure 4 This is a schematic diagram showing the result after pressing according to an embodiment of the present invention.

[0016] The reference numerals in the accompanying drawings are as follows: 1. Core board; 1a. First surface; 1b. Second surface; 11. Receiving groove; 111. First groove; 112. Second groove; 12. Substrate; 13. First copper layer; 14. Second copper layer; 2. Dielectric layer board; 21. Through groove; 3. Metal base; 31. First substrate; 32. Second substrate; 4. Electroplating layer. Detailed Implementation

[0017] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] like Figures 1 to 4 As shown, an embodiment of the present invention provides a metal-based embedding method, comprising the following steps: S10. Obtain the dielectric layer plate 2 and the core plate 1, and process the receiving groove 11 on the core plate 1; The dielectric layer 2 is an epoxy resin insulating dielectric material (e.g., PP), which serves as interlayer insulation, lamination bonding, and interlayer filling and isolation. The core board 1 is a copper-clad core board 1. Based on the outer dimensions of the metal base 3 and the preset assembly position, a receiving groove 11 is machined on the core board 1 using CNC milling or laser grooving technology. The outline dimensions of the receiving groove 11 are slightly larger than the outline dimensions of the metal base 3 to be assembled, leaving machining allowance for subsequent sidewall metallization, ensuring that the metal base 3 can be accurately aligned and embedded after the sidewall metallization is completed, meeting the requirements for lamination and pressing accuracy.

[0019] S20. Metallize the sidewalls of the receiving groove 11; For the receiving groove 11 opened on the core board 1, the sidewall of the receiving groove 11 is metallized. Specifically, it can be done through processes such as groove wall roughening, chemical copper plating, and electroplating thickening to deposit a dense electroplated layer 4 on the groove wall of the receiving groove 11, so that the groove wall of the receiving groove 11 forms a continuous conductive metal layer, thereby realizing interlayer conduction between the core board 1 and the embedded metal base 3.

[0020] S30. The dielectric layer 2 is placed between the two core plates 1, and the metal base 3 is placed in the metal base 3 groove formed by the connection of the two receiving grooves 11. By pressing, the metal base 3 is embedded in the multilayer board formed by the two core plates 1.

[0021] After the metallization of the tank wall is completed, the plates are stacked. The entire dielectric layer plate 2 is sandwiched between the two core plates 1 in the center. The receiving grooves 11 of the two core plates 1 are interconnected, forming a metal base 3 tank. The metal base 3 is placed in the metal base 3 tank, and the sidewall of the metal base 3 is directly attached to the electroplated layer 4 on the tank wall. Then, the whole is subjected to high temperature and high pressure vacuum pressing treatment. Through the pressing and bonding curing effect of the dielectric layer plate 2, the metal base 3, the two core plates 1 and the intermediate dielectric layer plate 2 are bonded and fixed into one piece. After the two core plates 1 and the dielectric layer plate 2 are fixed, a multi-layer plate structure is formed. The metal base 3 is embedded and fixed inside the multi-layer plate, completing the embedded assembly process of the metal base 3.

[0022] In this embodiment, the sidewalls of the receiving grooves 11 of the two core boards 1 are metallized. After the metal base 3 is assembled, it is directly bonded to the electroplated layer 4 of the groove wall to achieve conductivity. The metal base 3 replaces the electroplated copper of the through hole wall in the traditional process to realize the electrical connection path, construct the conductive path arranged along the groove wall, greatly increase the conductor conductive cross-sectional area, effectively improve the overall current carrying capacity, and meet the requirements of the circuit board for high current operation.

[0023] In addition, the metal-based 3 also has a heat dissipation function, which can quickly dissipate working heat and improve the heat dissipation efficiency of the circuit board.

[0024] Among them, high current refers to the maximum current value that a device, wire, or component can stably pass through over a long period of time within a safe range.

[0025] In one embodiment, such as Figure 2 As shown, the receiving groove 11 includes a first groove 111 and a second groove 112 that are interconnected; the step S10 of obtaining the dielectric layer plate 2 and the core plate 1, and machining the receiving groove 11 on the core plate 1 includes: S11. A first groove 111 is machined inward from the first surface 1a of the core plate 1; S12. A second groove 112 is machined from the bottom of the first groove 111 toward the second surface 1b of the core plate 1; wherein the first surface 1a and the second surface 1b are arranged opposite to each other.

[0026] The first groove 111 is formed from the first surface 1a inward by controlled depth milling process, and then the second groove 112 is milled from the bottom of the first groove 111 toward the second surface 1b. The depth of the second groove 112 is from the bottom of the first groove 111 to the second surface 1b. The first groove 111 and the second groove 112 are interconnected, and the central axis of the first groove 111 coincides with the central axis of the second groove 112.

[0027] Furthermore, in the horizontal direction, the cross-sectional area of ​​the first groove 111 is larger than that of the second groove 112 to form a stepped groove. After the two core plates 1 are stacked, they can enclose and form a metal base 3 groove. Through the stepped receiving groove 11, the melting of the medium layer plate 2 during the pressing process can be effectively prevented from flowing into and filling the gap between the metal base 3 and the electroplated layer 4 of the groove wall, ensuring contact between the metal base 3 and the electroplated layer 4 and ensuring electrical conductivity.

[0028] In other embodiments, the second groove 112 can be machined from the second surface 1b inward using a controlled deep milling process, and then the first groove 111 can be milled from the bottom of the second groove 112 towards the first surface 1a.

[0029] Controlled depth milling is a milling process in CNC machining. It mainly refers to machining a specific area of ​​a workpiece by precisely controlling the milling depth (Z-axis direction) to achieve the required size, shape, or surface quality.

[0030] In one embodiment, such as Figure 2 As shown, the core board 1 includes a substrate 12, a first copper layer 13 and a second copper layer 14. The first copper layer 13 and the second copper layer 14 are disposed on opposite sides of the substrate 12 in the thickness direction. The depth of the first groove 111 is controlled to extend from the surface of the first copper layer 13 to the middle of the substrate 12. The depth of the second groove 112 is controlled to penetrate from the bottom of the first groove 111 to the second copper layer 14.

[0031] In one embodiment, step S10, which involves obtaining the dielectric layer 2 and the core plate 1, and machining the receiving groove 11 on the core plate 1, further includes: A through groove 21 is machined on the dielectric layer 2; The through groove 21 is connected to the two receiving grooves 11 to form the metal base 3 groove.

[0032] like Figure 4 As shown, the through groove 21 penetrates the dielectric layer plate 2 in the thickness direction. The dielectric layer plate 2 is sandwiched between two core plates 1. The through groove 21 on the dielectric layer plate 2 is interconnected with the receiving grooves 11 of the two core plates 1, and the three together form a complete metal base 3 groove. When the metal base 3 is embedded in the metal base 3 groove, a gap is left between the groove wall of the through groove 21 and the metal base 3 to provide space for the melting and flow of the dielectric layer plate 2 during the pressing process. After solidification, the dielectric layer plate 2 and the metal base 3 are fixed.

[0033] In one embodiment, such as Figure 3As shown, the metal substrate 3 includes a first substrate 31 and a second substrate 32. The first substrate 31 is disposed around the second substrate 32, and the first substrate 31 extends outward from the outer periphery of the second substrate 32. In the axial direction, the second substrate 32 protrudes beyond the first substrate 31. During milling, the cross-sectional area of ​​the first groove 111 is slightly larger than the cross-sectional area of ​​the first substrate 31, and the cross-sectional area of ​​the second groove 112 is slightly larger than the cross-sectional area of ​​the second substrate 32, thereby leaving space for the electroplated layer 4 formed by the metallization process.

[0034] Specifically, the first substrate 31 is annular, the second substrate 32 is cylindrical, and correspondingly, the first groove 111 and the second groove 112 are both circular. The outer diameter of the first substrate 31 is set to φ1, the outer diameter of the second substrate 32 to φ2, and the thickness of the first substrate 31 to h. After the receiving groove 11 is processed, the diameter of the first groove 111 is slightly larger than φ1, the diameter of the second groove 112 is slightly larger than φ2, and the diameter of the through groove 21 is slightly larger than φ1.

[0035] After the sidewall metallization is completed, the metallized first groove 111 is covered by an electroplating layer 4, and the effective diameter of the metallized first groove 111 becomes φ1, while the depth of the first groove 111 is controlled to be h / 2. The effective diameter of the metallized second groove 112 becomes φ2. After the dielectric layer 2 and the two core plates 1 are stacked, the first substrate 31 is housed in the cavity enclosed by the through groove 21 and the two first grooves 111, and the two ends of the second substrate 32 are respectively placed in the two second grooves 112.

[0036] In one embodiment, such as Figure 4 As shown, step S30, which involves placing the dielectric layer 2 between the two core plates 1, placing the metal base 3 in the metal base 3 groove formed by the two receiving grooves 11, and embedding the metal base 3 into the multilayer board formed by pressing together the two core plates 1, includes: The dielectric layer 2 is stacked on the first core plate 1, and one end of the metal base 3 is placed in the through groove 21 and the receiving groove 11 of the first core plate 1; the second core plate 1 is sleeved on the metal base 3, and the other end of the metal base 3 is placed in the receiving groove 11 of the second core plate 1, wherein the two core plates 1 are placed opposite each other.

[0037] During the actual assembling process, first align and stack the dielectric layer board 2 on the first surface 1a of the first core board 1, keep the through groove 21 on the dielectric layer board 2 aligned with the accommodating groove 11 of the core board 1, so that they communicate with each other; then pass one end of the metal base 3 through the through groove 21 and the accommodating groove 11 of the first core board 1 in sequence to complete preliminary positioning. Then take the second core board 1, make the first surface 1a of the second core board 1 face the dielectric layer board 2, sleeve it on the other end of the metal base 3 in alignment from top to bottom, so that the other end of the metal base 3 is embedded into the accommodating groove 11 of the second core board 1. After assembling is completed, pressing is performed, and the bonding and fixing of the metal base 3 and the two core boards 1 is realized through melting and flowing of the dielectric layer board 2.

[0038] wherein, as Figure 4 shown, the through groove 21 is arranged between the first grooves 111 of the two core boards 1, and the two first grooves 111, the two second grooves 112 and the through groove 21 communicate to form a "middle"-shaped groove for the metal base 3, which can prevent molten material from filling the gap between the metal base 3 and the groove wall of the accommodating groove 11 during pressing, thereby ensuring the contact reliability between the metal base 3 and the plating layer 4 on the groove wall.

[0039] In one embodiment, as Figure 2 shown, the sidewall metallization of the groove wall of the accommodating groove 11 in step S20 includes: sidewall metallization is performed by a copper deposition electroplating process, so that the plating layer 4 is deposited on the first surface 1a, the second surface 1b and the groove wall of the accommodating groove 11.

[0040] The plating layer 4 is deposited on the first copper layer 13, the second copper layer 14 and the groove wall of the accommodating groove 11, the board surface of the core board 1 and the groove wall form a continuous and complete conductive plating layer, which realizes the metallization of the sidewall of the accommodating groove 11, establishes a conductive path, and at the same time, the plating layer on the groove wall and the plating layer on the board surface are connected into one body, further ensuring the continuity and stability of the overall electrical conduction.

[0041] wherein, electroplating refers to reducing metal ions (such as copper, gold, nickel, etc.) from electrolyte through electrolytic reaction and depositing them on conductive areas (such as hole walls, circuit surfaces).

[0042] In this embodiment, the plating layer 4 is a copper layer.

[0043] In one embodiment, after the sidewall metallization of the groove wall of the accommodating groove 11, the method includes: performing pattern circuit processing on the first surface 1a of the core board 1.

[0044] After the sidewall metallization is completed, a plating layer is deposited on the first surface 1a. A dry film is attached on the plating layer, and exposure, development and etching operations are performed in sequence. The plating layer and the first copper layer 13 in non-circuit areas on the dry film are removed, then the dry film is peeled off, and finally an inner layer pattern circuit is formed on the core board 1.

[0045] In one embodiment, after step S30 is completed, the process further includes: performing patterned circuit processing on the second surface 1b of the core board 1.

[0046] The second copper layer 14 and the electroplated layer deposited on it on the multilayer board maintain an intact copper surface. After lamination is completed, it is exposed, developed and etched to remove the electroplated layer and the second copper layer 14 in the non-circuit area, thereby preparing the outer layer pattern circuit.

[0047] In one embodiment, the metal base 3 is copper-based, aluminum-based, or aluminum alloy-based.

[0048] An embodiment of the present invention also provides a method for preparing a metal-based circuit board, including the metal-based embedding method described in any of the above claims; The method for preparing the metal-based 3D circuit board further includes: At least one uplayer is laminated on the multilayer board, and metallized holes and patterned circuits are processed on the uplayer. Repeat the above steps until the target number of layers is reached to obtain a metal-based 3-layer circuit board.

[0049] Specifically, the overlay is laminated onto at least one side of the multilayer board, followed by blind via fabrication. The depth of the blind via is controlled to extend from the surface of the overlay to the surface of the multilayer board. The blind via is metallized by electroplating to obtain metallized vias. During the metallization process, a seed layer is deposited on the surface of the overlay. A dry film is then attached to the seed layer, followed by exposure, development, and etching processes to form patterned circuits on the overlay.

[0050] By laminating new layers one by one and completing the metallization of blind vias and the processing of patterned circuits, the total number of circuit board layers can be continuously increased to meet the product design requirements of different number of layers and different wiring densities.

[0051] In one embodiment, the added layer includes a substrate and a copper metal layer. The substrate is stacked on the second surface 1b of the core board 1, and the copper metal layer is disposed on the side of the substrate away from the core board 1. During the blind via metallization process, a seed layer is deposited on the copper metal layer, and then a dry film is attached to the seed layer. Exposure, development and etching processes are performed in sequence to remove the seed layer and copper metal layer in the non-circuit area to obtain the patterned circuit.

[0052] An embodiment of the present invention also provides a metal-based 3-circuit board, which is prepared by the above-described method for preparing a metal-based 3-circuit board.

[0053] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A metal-based embedding method, characterized in that, include: Obtain a dielectric layer plate and a core plate, and machine a receiving groove on the core plate; The sidewalls of the receiving groove are metallized; The dielectric layer is placed between the two core plates, and the metal base is placed in the metal base groove formed by the connection of the two receiving grooves. By pressing, the metal base is embedded in the multilayer board formed by the two core plates.

2. The metal-based embedding method according to claim 1, characterized in that, The receiving slot includes a first slot and a second slot that are interconnected; The process of obtaining the dielectric layer and core plate, and machining a receiving groove on the core plate includes: A first groove is machined inward from the first surface of the core board; A second groove is machined from the bottom of the first groove toward the second surface of the core plate; wherein the first surface and the second surface are arranged opposite to each other.

3. The metal-based embedding method according to claim 2, characterized in that, The process of obtaining the dielectric layer and core plate, and machining a receiving groove on the core plate, further includes: A through groove is machined into the dielectric layer plate; The through groove is connected to the two receiving grooves to form the metal base groove.

4. The metal-based embedding method according to claim 3, characterized in that, The step of placing the dielectric layer between the two core plates, placing the metal substrate in the metal substrate groove formed by the two receiving grooves, and embedding the metal substrate into the multilayer board formed by the two core plates by pressing includes: The dielectric layer is stacked on the first core plate, and one end of the metal base is placed in the through groove and the receiving groove of the first core plate; The second core plate is fitted onto the metal base, and the other end of the metal base is placed in the receiving groove of the second core plate, wherein the two core plates are placed opposite each other.

5. The metal-based embedding method according to claim 2, characterized in that, The sidewall metallization of the receiving groove includes: The sidewalls are metallized by a copper plating process, so that an electroplated layer is deposited on the first surface, the second surface, and the wall of the receiving tank.

6. The metal-based embedding method according to claim 5, characterized in that, The process of metallizing the sidewalls of the receiving groove includes: Patterned circuitry is performed on the first surface of the core board.

7. The metal-based embedding method according to claim 5, characterized in that, The metal substrate includes a first substrate and a second substrate, the first substrate is disposed around the second substrate, the diameter of the first substrate is φ1, the diameter of the second substrate is φ2, and the thickness of the first substrate is h; The diameter of the first metallized groove is φ1, the depth of the first groove is h / 2, and the diameter of the second metallized groove is φ2.

8. The metal-based embedding method according to claim 1, characterized in that, The metal base is copper-based, aluminum-based, or aluminum alloy-based.

9. A method for preparing a metal-based circuit board, characterized in that, Including the metal-based embedding method according to any one of claims 1-8; The method for preparing the metal-based circuit board further includes: At least one uplayer is laminated on the multilayer board, and metallized holes and patterned circuits are processed on the uplayer. Repeat the above steps until the target number of layers is reached to obtain a metal-based circuit board.

10. A metal-based circuit board, characterized in that, It is prepared by the method for preparing the metal-based circuit board according to claim 9.

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