Manufacturing method of circuit board, circuit board and circuit board assembly
By filling the second circuit layer of the circuit board with epoxy resin-based inorganic thermally conductive materials and high thermal conductivity materials to form a filling layer and a thermally conductive layer, the problem of poor bonding quality between the circuit board and the heat sink interface is solved, achieving more efficient heat dissipation and more stable material properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENNAN CIRCUITS
- Filing Date
- 2026-01-06
- Publication Date
- 2026-05-19
AI Technical Summary
In the existing technology, the interface between the outermost layer of the circuit board and the heat sink is of poor quality, with problems such as insufficient filling, high interface thermal resistance, weak bonding force and material aging, resulting in poor heat dissipation performance and affecting chip performance and reliability.
A first thermally conductive material is used to fill the non-circuit area of the second circuit layer of the circuit board to form a filling layer, and a second thermally conductive material is laid on top of it to form a thermally conductive layer. Both are epoxy resins mixed with inorganic and high thermally conductive materials to ensure tight bonding at the molecular level and improve the quality of interface bonding.
It improves the interfacial bonding between the heat sink and the circuit board, reduces the interfacial thermal resistance, ensures the stability of the material in high temperature and high humidity environments, extends the service life, and improves the performance and reliability of the chip.
Smart Images
Figure CN122069655A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of heat dissipation technology for electronic devices, and in particular to a method for manufacturing a circuit board, a circuit board, and a circuit board assembly. Background Technology
[0002] In recent years, to meet the demands for extreme miniaturization and high performance in electronic products, embedded power chip technology has been increasingly widely used. Embedded power chips are no longer surface-mounted on the circuit board, but are directly embedded and packaged within the internal layers of the circuit board. This structure saves layout space and improves system integration.
[0003] However, because the power chip is deeply embedded in an internal layer composed of resin and fiberglass, the heat generated during operation cannot be dissipated through the air. It must be conducted to the heat sink on the outer surface of the circuit board through a complex heat dissipation path, which is usually long and has high thermal resistance. Therefore, the interface between the outermost layer of the circuit board and the heat sink becomes the most critical link in the entire heat dissipation chain.
[0004] The outermost layer of a circuit board is typically a circuit layer with copper traces. The layout of these copper traces creates an uneven, gap-filled, non-planar structure. Related technologies use thermal interface materials, such as thermal grease, thermal pads, or phase change materials, to fill this non-planar structure, but these methods often have the following drawbacks: 1. Insufficient filling: Under installation pressure, the thermal interface material cannot completely expel air from the non-planar structure, which easily leaves behind tiny air bubbles and forms local hot spots.
[0005] 2. High interface thermal resistance, bubbles and insufficiently filled areas will form thermal barriers, hindering the efficient transfer of heat from the circuit board to the heat sink, causing the chip junction temperature to rise and reducing the chip's performance and reliability.
[0006] 3. Weak bonding force and insufficient filling result in insufficient adhesion between the thermal interface material and the circuit board. When mechanical vibration or thermal stress caused by temperature cycling occurs, the thermal interface material is prone to cracks or even peeling off from the circuit board, further deteriorating the heat dissipation performance.
[0007] 4. Material aging: When the thermal interface material is exposed to high temperature for a long time, it is prone to drying out, carbonization, or pumping effect, which leads to the degradation of thermal performance and difficulty in reducing reliability.
[0008] Based on the above defects, it can be seen that the interface quality between the outermost layer of the circuit board and the heat sink in the relevant technology is poor and still needs improvement. Summary of the Invention
[0009] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for manufacturing a circuit board, a circuit board, and a circuit board assembly. A first thermally conductive material is used to fill the non-circuit area of a second circuit layer to form a fill layer. A second thermally conductive material is laid on the second circuit layer and the fill layer to form a thermally conductive layer. Both the fill layer and the thermally conductive layer have epoxy resin as their organic matrix, thereby ensuring perfect compatibility and tight bonding between the fill layer and the thermally conductive layer at the molecular level, greatly improving the bonding strength, and thus improving the interface bonding quality between the heat sink and the circuit board.
[0010] The method for manufacturing a circuit board according to an embodiment of the present invention includes: An initial circuit board is provided, the initial circuit board including a substrate and a first circuit layer and a second circuit layer disposed on both sides of the substrate; A first thermally conductive material is used to fill the non-circuit area of the second circuit layer to form a filling layer, wherein the first thermally conductive material includes an epoxy resin mixed with an inorganic thermally conductive material. A second thermally conductive material is disposed on the second circuit layer and the filler layer to form a thermally conductive layer, wherein the second thermally conductive material is an epoxy resin mixed with a high thermal conductivity material.
[0011] In some embodiments, before forming a thermally conductive layer by depositing a second thermally conductive material on the second circuit layer and the filler layer, the method further includes: The filler layer and the second circuit layer are ground to make them flush and form a smooth surface.
[0012] In some embodiments, the non-circuit regions of the second circuit layer are filled using the first thermally conductive material and by vacuum plugging to form a filling layer.
[0013] In some embodiments, a second thermally conductive material is deposited on the second circuit layer and the filler layer by lamination or coating to form a thermally conductive layer.
[0014] In some embodiments, providing the initial circuit board includes: providing a substrate in which power devices are embedded.
[0015] The circuit board of this invention includes an initial circuit board, a filler layer, and a thermally conductive layer. The initial circuit board includes a substrate and a first circuit layer and a second circuit layer attached to both sides of the substrate. The filler layer fills the non-circuit area of the second circuit layer, and the filler layer is made of epoxy resin mixed with an inorganic thermally conductive material. The thermally conductive layer is disposed on the second circuit layer and the filler layer, and the thermally conductive layer is made of epoxy resin mixed with a highly thermally conductive material.
[0016] In some embodiments, the inorganic thermally conductive material has a mass fraction of less than or equal to 30% in the filler layer, and the high thermal conductivity material has a mass fraction of 85% in the thermally conductive layer.
[0017] In some embodiments, the circuit board further includes power devices embedded within the substrate.
[0018] In some embodiments, the method further includes a first copper layer disposed on the side of the first circuit layer away from the substrate, and a third circuit layer formed on the first copper layer, the third circuit layer being electrically connected to the first circuit layer.
[0019] The circuit board assembly of this invention includes a circuit board and a heat sink as described in any one of claims 6 to 9, wherein the heat sink is connected to the thermally conductive layer of the circuit board.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: A first thermally conductive material is used to fill the non-circuit areas of the second circuit layer, thus forming a filler layer. A second thermally conductive material is then laid on the second circuit layer and the filler layer, thus forming a thermally conductive layer. Because the filler layer has formed a flat structure with the second circuit layer through the filling step, the thermally conductive layer will not be trapped in the aforementioned non-circuit areas, making it easier to form. Furthermore, the flat thermally conductive layer and the filler layer create a large contact area. Since both the thermally conductive layer and the filler layer are based on epoxy resin, perfect compatibility and tight bonding at the molecular level are ensured, greatly improving the bonding strength. This improves the interface bonding quality between the heat sink connected to the subsequent thermally conductive layer and the circuit board.
[0021] Furthermore, the fluidity of epoxy resin allows for more thorough filling of non-circuit areas, and the presence of inorganic and highly thermally conductive materials enables faster and more efficient heat dissipation, reducing interfacial thermal resistance and preventing a continuous rise in the junction temperature of embedded chips on the circuit board, thus ensuring chip performance and reliability. Additionally, the first and second thermally conductive materials are composites of epoxy resin and thermally conductive materials, avoiding the aging and pump-out problems associated with materials like silicone grease in related technologies. This ensures stable performance even in harsh environments such as high temperature and high humidity, extending service life and improving reliability. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic flowchart illustrating the circuit board manufacturing method according to an embodiment of the present invention.
[0024] Figure 2 This is a schematic diagram of the process of forming a substrate according to an embodiment of the present invention.
[0025] Figure 3 This is a schematic diagram of the structure of the initial circuit board according to an embodiment of the present invention.
[0026] Figure 4 This is another structural schematic diagram of the initial circuit board according to an embodiment of the present invention.
[0027] Figure 5 This is a schematic diagram of the circuit board structure according to an embodiment of the present invention.
[0028] Figure 6 This is a schematic diagram of the circuit board assembly according to an embodiment of the present invention.
[0029] Figure label: 10. Initial circuit board; 11. Substrate; 111. Base material; 112. Second copper layer; 112a. First circuit layer; 113. Third copper layer; 113a. Second circuit layer; 12. Filler layer; 13. Thermally conductive layer; 14. Prepreg; 141. First via; 142. Second via; 143. Third via; 15. Power device; 151. Power chip; 152. First copper block; 153. Second copper block; 20. Circuit board; 21. First copper layer; 211. Third circuit layer; 30. Circuit board assembly; 31. Heat sink. Detailed Implementation
[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0031] The following is combined Figures 1 to 6 This invention describes a method for manufacturing a circuit board, the circuit board itself, and circuit board assemblies according to embodiments of the present invention.
[0032] refer to Figure 1 This invention provides a method for manufacturing a circuit board, comprising the following steps: 110. An initial circuit board is provided, the initial circuit board including a substrate and a first circuit layer and a second circuit layer disposed on both sides of the substrate; 120. A filling layer is formed by filling the non-circuit area of the second circuit layer with a first thermally conductive material, wherein the first thermally conductive material includes epoxy resin mixed with inorganic thermally conductive materials. 130. A second thermally conductive material is disposed on the second circuit layer and the filler layer to form a thermally conductive layer. The second thermally conductive material is an epoxy resin mixed with a high thermal conductivity material.
[0033] The first thermally conductive material uses epoxy resin as the organic matrix and inorganic thermally conductive materials as fillers. The inorganic thermally conductive materials are dispersed in the epoxy resin in a particulate form, specifically silicon dioxide, aluminum oxide, etc. The second thermally conductive material uses epoxy resin as the organic matrix and high thermal conductivity materials as fillers. The high thermal conductivity materials are dispersed in the epoxy resin in a particulate form, specifically boron nitride, aluminum nitride, etc.
[0034] The circuit board manufacturing method of this invention involves filling the non-circuit areas of the second circuit layer with a first thermally conductive material to form a filling layer. Since the matrix of the first thermally conductive material is epoxy resin, it has excellent flowability and adhesion. Therefore, the first thermally conductive material fills the aforementioned non-circuit areas more thoroughly and is less prone to detachment after filling. The inorganic thermally conductive material in the first thermally conductive material has high thermal conductivity and is used to establish thermal conduction pathways in the matrix, facilitating the dissipation of heat from the circuit board.
[0035] Subsequently, a second thermally conductive material is laid on the second circuit layer and the filler layer to form a thermally conductive layer. Since the filler layer has formed a flat structure with the second circuit layer through the filling step, the thermally conductive layer will not be embedded in the aforementioned non-circuit areas, making it easier to form. Furthermore, the flat thermally conductive layer and the filler layer create a large contact area. Since both the thermally conductive layer and the filler layer are based on epoxy resin, perfect compatibility and tight bonding at the molecular level are ensured, greatly enhancing the bonding strength. A heat sink can then be soldered onto the thermally conductive layer. Through the above process, the interface bonding quality between the heat sink and the circuit board is greatly improved, making separation much more difficult.
[0036] It should be noted that the filler in the second thermally conductive material is a high thermal conductivity material, such as boron nitride or aluminum nitride. High thermal conductivity materials have excellent thermal conductivity, which not only guides the heat dissipation from the inorganic thermally conductive material to the heat sink but also accelerates heat dissipation, making heat dissipation faster and more efficient. This also reduces interfacial thermal resistance, lowering the junction temperature of the chips within the circuit board and ensuring chip performance and reliability. Furthermore, the first and second thermally conductive materials are composed of epoxy resin and filler composites, avoiding the aging and pump-out problems of materials such as silicone grease in related technologies. They maintain stable performance even in harsh environments such as high temperature and high humidity, extending service life and improving reliability.
[0037] In some embodiments, reference Figure 2 The substrate is prepared by the following method: 111, Provide a substrate, and laminate a second copper layer and a third copper layer onto both sides of the substrate using prepreg; 112, A first circuit layer is formed on the second copper layer, and a second circuit layer is formed on the third copper layer.
[0038] The substrate can be FR4 (epoxy fiberglass) or other high-frequency substrates for mechanical support. The second and third copper layers can be made of copper foil.
[0039] Continue to refer to Figure 4 During the pressing process, the second copper layer 112, the substrate 111, the third copper layer 113, and the prepreg 14 between each layer are fed into the press together. Under the high temperature and high pressure of the press, the prepreg 14 flows and impregnates the second copper layer 112 and the third copper layer 113. After cooling, it is cured, so that the second copper layer 112, the third copper layer 113 and the substrate 111 are firmly bonded together.
[0040] Continue to refer to Figure 3 In step 112, the second copper layer 112 and the third copper layer 113 are formed by chemical etching to form the first circuit layer 112a and the second circuit layer 113a.
[0041] In some embodiments, before step 130, which involves depositing a second thermally conductive material on the second circuit layer and the filler layer to form a thermally conductive layer, the method further includes grinding the filler layer and the second circuit layer to make the filler layer and the second circuit layer flush to form a smooth surface.
[0042] The formation of this smooth surface enhances the bonding effect of the subsequent second thermally conductive material, making the thermally conductive layer and the filler layer bond more firmly, and further improving the bonding quality between the heat sink and the circuit board.
[0043] In some embodiments, a first thermally conductive material is used and a vacuum plugging method is employed to fill the non-circuit area of the second circuit layer to form a fill layer.
[0044] Vacuum plugging involves placing the circuit board in a vacuum chamber, removing all air, and then pressing a first thermally conductive material into the non-circuit area under vacuum conditions. Because there is no air, the first thermally conductive material can completely fill every part of the non-circuit area, achieving complete and thorough filling without leaving any air bubbles, thus preventing the formation of localized hotspots that hinder heat conduction.
[0045] In some embodiments, a second thermally conductive material is applied to the second circuit layer and the filler layer by lamination or coating to form a thermally conductive layer.
[0046] Lamination and coating offer two implementation methods, providing a wider range of options for how the thermally conductive layer and the filler layer are bonded.
[0047] In some embodiments, step 110, providing an initial circuit board, includes: providing a substrate and embedding power devices within the substrate.
[0048] It should be noted that the reference Figure 3Before the substrate 11 is fabricated, the substrate 111 is cut to form one or more cavities. When there are multiple cavities, they are spaced apart. The cutting method can be laser cutting, mechanical cutting, etc. The shape, size, and depth of the cavity can be set according to requirements. In this embodiment, the cavity is a square cavity that penetrates the substrate 111.
[0049] Continue to refer to Figure 4 The number of power devices 15 is the same as the number of cavities, with one power device 15 embedded in each cavity. In this embodiment, the power device 15 is a power chip 151, but in other embodiments it can also be an electronic component such as a resistor, capacitor, or inductor.
[0050] Continue to refer to Figure 4 Along with the power chip 151 embedded in the cavity, there are also two copper blocks. One of them is located above the power chip 151 and is called the first copper block 152. A first via 141 is formed on the prepreg 14 between the first copper block 152 and the first circuit layer 112a. The first via 141 connects the first copper block 152 and the first circuit layer 112a. A metal layer is formed on the inner wall of the first via 141 by sputtering, electroplating or other methods. The metal layer can be a copper layer, silver layer or other materials with good conductivity. This metal layer makes the first copper block 152 electrically connected to the first circuit layer 112a, thereby realizing the electrical connection between the power chip 151 and the first circuit layer 112a, which facilitates signal transmission.
[0051] Continue to refer to Figure 4 One of the two copper blocks is located below the power chip 151 and is referred to as the second copper block 153. A second via 142 is formed on the prepreg 14 between the second copper block 153 and the second circuit layer 113a. The second via 142 connects the second copper block 153 and the second circuit layer 113a. A metal layer is formed on the inner wall of the second via 142 by sputtering, electroplating, or other methods. The metal layer can be a copper layer, silver layer, or other materials with good conductivity. This metal layer electrically connects the second copper block 153 and the second circuit layer 113a, thereby realizing the electrical connection between the power chip 151 and the second circuit layer 113a, facilitating signal transmission. Further, refer to... Figure 3 , Figure 4 and Figure 6 The metal layer inside the second copper block 153 and the second via 142 also establishes a heat conduction path between the power chip 151 and the second circuit layer 113a, so that the heat of the power chip 151 is conducted to the second circuit layer 113a through this heat conduction path, and then to the fill layer 12 and the heat conduction layer 13, and then dissipated to the outside through the heat sink 31.
[0052] This invention also provides a circuit board 20, which is prepared by the circuit board manufacturing method described in the above embodiments.
[0053] refer to Figure 3 The circuit board 20 includes an initial circuit board 2010, a filler layer 12, and a thermally conductive layer 13. The initial circuit board 2010 includes a substrate 11 and a first circuit layer 112a and a second circuit layer 113a attached to both sides of the substrate 11. The filler layer 12 fills the non-circuit area of the second circuit layer 113a, and the material of the filler layer 12 includes epoxy resin mixed with inorganic thermally conductive materials; the thermally conductive layer 13 is disposed on the second circuit layer 113a and the filler layer 12, and the material of the thermally conductive layer 13 includes epoxy resin mixed with highly thermally conductive materials.
[0054] The specific implementation and technical advantages of the circuit board 20 in this embodiment can be found in the description of the circuit board manufacturing method in the above embodiment, and will not be repeated here.
[0055] In some embodiments, the mass fraction of inorganic thermally conductive material in the filler layer 12 is less than or equal to 30%, and the mass fraction of high thermal conductivity material in the thermally conductive layer 13 is equal to 85%.
[0056] Among them, inorganic thermally conductive materials include silicon dioxide and aluminum oxide, while high thermally conductive materials include boron nitride and aluminum nitride.
[0057] The inorganic thermally conductive material has a small mass fraction in the filler layer 12, which ensures that the epoxy resin in the filler layer 12 has high fluidity, so as to facilitate the flow and filling of the non-circuit area of the first circuit layer 112a, making the filling more complete and thorough. The high thermal conductivity material has a large mass fraction in the thermally conductive layer 13, which can improve the thermal conductivity of the thermally conductive layer 13, achieve excellent thermal conductivity, and facilitate the rapid dissipation of heat from the circuit board 20.
[0058] In some embodiments, continue to refer to Figure 3 and Figure 4 The circuit board 20 also includes a power device 15 embedded in the substrate 11. In this embodiment, the power device 15 may be a power chip 151.
[0059] The implementation method and heat dissipation method of the power chip 151 can be referred to the description in the circuit board manufacturing method of the above embodiment, and will not be repeated here.
[0060] In some embodiments, continue to refer to Figure 5 The circuit board 20 also includes a first copper layer 21, which is disposed on the side of the first circuit layer 112a away from the substrate 11. A third circuit layer 211 is formed on the first copper layer 21, and the third circuit layer 211 is electrically connected to the first circuit layer 112a.
[0061] After forming the first circuit layer 112a on the second copper layer 112, the first copper layer 21 is laminated onto the second copper layer 112 / first circuit layer 112a using a prepreg 14 and a press. Then, a third circuit layer 211 is chemically etched onto the first copper layer 21. A third via 143 is formed on the prepreg 14 between the third circuit layer 211 and the first circuit layer 112a. A metal layer is plated on the inner wall of the third via 143. This metal layer electrically connects the first circuit layer 112a and the third circuit layer 211, enabling conductivity and signal transmission between them. This metal layer can be a copper layer, a silver layer, or other materials with good conductivity.
[0062] Continue to refer to Figure 6 The present invention also provides a circuit board assembly 30, including a circuit board 20 and a heat sink 31, wherein the heat sink 31 is connected to the thermally conductive layer 13 of the circuit board 20.
[0063] The heat sink 31 is welded to the heat-conducting layer 13 by reflow soldering or sintering silver process.
[0064] Compared to conventional screw installation and adhesive bonding processes, reflow soldering or sintered silver processes can improve the mechanical strength of the weld, making it less prone to loosening and more reliable. Furthermore, the solder produced by reflow soldering or sintered silver processes has higher thermal conductivity, resulting in lower interfacial thermal resistance between the heat sink 31 and the thermally conductive layer 13, which is more conducive to heat dissipation.
[0065] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0066] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0067] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0068] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0069] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0070] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A method for manufacturing a circuit board, characterized in that, include: An initial circuit board is provided, the initial circuit board including a substrate and a first circuit layer and a second circuit layer disposed on both sides of the substrate; A first thermally conductive material is used to fill the non-circuit area of the second circuit layer to form a filling layer, wherein the first thermally conductive material includes an epoxy resin mixed with an inorganic thermally conductive material. A second thermally conductive material is disposed on the second circuit layer and the filler layer to form a thermally conductive layer, wherein the second thermally conductive material is an epoxy resin mixed with a high thermal conductivity material.
2. The method for manufacturing a circuit board according to claim 1, characterized in that, Before forming a thermally conductive layer by depositing a second thermally conductive material on the second circuit layer and the filler layer, the method further includes: The filler layer and the second circuit layer are ground to make them flush and form a smooth surface.
3. The method for manufacturing a circuit board according to claim 1, characterized in that, The non-circuit area of the second circuit layer is filled using the first thermally conductive material and by vacuum plugging to form a filling layer.
4. The method for manufacturing a circuit board according to claim 1, characterized in that, A second thermally conductive layer is formed by laminating or coating a second thermally conductive material onto the second circuit layer and the filler layer.
5. The method for manufacturing a circuit board according to claim 1, characterized in that, The provision of the initial circuit board includes: providing a substrate in which power devices are embedded.
6. A circuit board, characterized in that, include: An initial circuit board, the initial circuit board comprising a substrate and a first circuit layer and a second circuit layer attached to both sides of the substrate; A filler layer, filling the non-circuit area of the second circuit layer, wherein the filler layer is made of epoxy resin mixed with inorganic thermally conductive materials; A thermally conductive layer is disposed on the second circuit layer and the filler layer, and the material of the thermally conductive layer includes epoxy resin mixed with a highly thermally conductive material.
7. The circuit board according to claim 6, characterized in that, The inorganic thermally conductive material has a mass fraction of less than or equal to 30% in the filler layer, and the high thermal conductivity material has a mass fraction of 85% in the thermally conductive layer.
8. The circuit board according to claim 6, characterized in that, It also includes power devices embedded in the substrate.
9. The circuit board according to claim 6, characterized in that, It also includes a first copper layer, which is disposed on the side of the first circuit layer away from the substrate, and a third circuit layer is formed on the first copper layer, which is electrically connected to the first circuit layer.
10. A circuit board assembly, characterized in that, include: The circuit board as described in any one of claims 6 to 9; The heat sink is connected to the thermally conductive layer of the circuit board.