A high thermal conductivity multilayer circuit board buried copper structure

Abstract

This invention provides a high thermal conductivity multilayer circuit board copper-buried structure, including a circuit board body, a copper-buried assembly disposed inside the circuit board body, and a chip disposed on top of the circuit board body. The circuit board body includes, from top to bottom, a first copper layer, a first adhesive layer, a core board, a second adhesive layer, and a second copper layer. The core board has a mounting groove extending along its thickness direction. A thermally conductive via is provided above the mounting groove, extending along the thickness direction through the first copper layer and the first adhesive layer. The second adhesive layer has heat dissipation holes located below the mounting groove. The copper-buried assembly is disposed within the mounting groove and includes a copper block and a thermally conductive layer disposed on top of the copper block. The upper and lower ends of the thermally conductive via are respectively connected to the bottom surface of the chip and the thermally conductive layer, and the upper and lower ends of the heat dissipation holes are respectively connected to the bottom surface of the copper block and the second copper layer. This multilayer circuit board copper-buried structure can effectively improve the overall thermal conductivity, which is beneficial for chip cooling and improves heat dissipation efficiency.

Description

Technical Field

[0001] This utility model relates to the field of circuit board manufacturing technology, and more specifically, to a multilayer circuit board with high thermal conductivity and embedded copper structure. Background Technology

[0002] Embedded copper is a technique to improve the heat dissipation and overcurrent of PCB boards. Because thick copper in a local area can directly conduct or carry large currents, it has high thermal conductivity. Embedding copper blocks in the circuit board can significantly enhance the heat dissipation effect of the circuit board.

[0003] Based on this, existing technologies typically embed copper blocks inside the PCB board beneath the chip. The copper blocks conduct the heat generated on the chip to the back of the PCB board, thereby enhancing the heat dissipation effect of the chip and preventing the chip temperature from becoming too high and affecting its working performance. Current methods for embedding copper mainly involve creating slots in the middle layer of a multilayer circuit board using a router-step approach to fit the copper block. The copper block is then placed into these slots, and finally, it is embedded into the circuit board through lamination. This method requires extremely high precision in the machining of the slot size and depth. When the machining dimensions deviate, a height difference can easily exist between the end faces of the copper block and the slot, potentially causing gaps between the copper block and adjacent layers, affecting heat conduction. Furthermore, the height difference can also make lamination difficult. In addition, since the connections between layers in a multilayer circuit board are achieved through adhesive structures, heat from the chip must pass through several layers of adhesive structures before being conducted to the copper block. Currently, prepreg (PP) sheets are commonly used for these adhesive structures. This material has low thermal conductivity and high thermal resistance, severely reducing the chip's heat dissipation efficiency and affecting its heat dissipation performance. Utility Model Content

[0004] In view of this, the present invention provides a multilayer circuit board buried copper structure with high thermal conductivity, which can effectively improve the overall thermal conductivity of the circuit board and improve heat dissipation efficiency, thereby facilitating the rapid reduction of chip temperature.

[0005] This utility model is achieved through the following technical solution.

[0006] A high thermal conductivity multilayer circuit board buried copper structure includes: a circuit board body, comprising a first copper layer, a first adhesive layer, a core board, a second adhesive layer, and a second copper layer stacked from top to bottom; the core board having a mounting groove extending along the thickness direction; a thermally conductive via being provided above the mounting groove; the thermally conductive via extending along the thickness direction through the first copper layer and the first adhesive layer; and a heat dissipation hole being provided in the second adhesive layer, the heat dissipation hole being located below the mounting groove; a buried copper assembly disposed within the mounting groove; the buried copper assembly comprising a copper block and a thermally conductive layer disposed on top of the copper block; and a chip disposed on top of the circuit board body; wherein the upper and lower ends of the thermally conductive via are respectively connected to the bottom surface of the chip and the thermally conductive layer, and the upper and lower ends of the heat dissipation hole are respectively connected to the bottom surface of the copper block and the second copper layer.

[0007] In the above solution, the thermally conductive layer is made of a material with good thermal conductivity. The heat generated during chip operation can be transferred to the thermally conductive layer through the underlying thermal vias. The thermally conductive layer then evenly transfers the heat to the copper block. Subsequently, the heat is conducted to the back of the circuit board through the heat dissipation holes below the copper block, thus achieving heat dissipation for the chip. Since the adhesive layer in the circuit board has low thermal conductivity and high thermal resistance, this application uses thermal vias to transfer heat, avoiding the influence of the low thermal conductivity of the adhesive layer, improving the heat conduction rate, and facilitating rapid heat dissipation for the chip, thereby improving heat dissipation efficiency. Furthermore, heat dissipation holes are provided on the second adhesive layer below the copper block, allowing heat to pass through... By setting heat dissipation holes on the second adhesive layer, the thermal conductivity of the second adhesive layer can be improved, which helps to conduct and dissipate heat from the copper block to the bottom surface of the circuit board more efficiently. In addition, during the lamination process, the thermally conductive layer on the copper block can fill the gap between the copper block and the first adhesive layer, preventing gaps from appearing between the copper block and the first adhesive layer due to processing errors. This ensures the reliability of heat conduction and guarantees the normal progress of the lamination process. Furthermore, the thermally conductive layer can disperse the heat transferred through the thermally conductive vias, allowing the heat to be transferred more evenly to the top surface of the copper block, which helps the copper block to conduct heat more efficiently and improves heat dissipation efficiency.

[0008] In one example of this invention, the diameter of the thermally conductive via gradually decreases from top to bottom.

[0009] In the above scheme, the larger diameter end of the thermal via is in contact with the bottom surface of the chip, which is conducive to quickly receiving heat from the chip. As the diameter of the thermal via decreases downwards, the speed at which heat is conducted towards the buried copper component gradually increases, thereby improving the heat conduction speed.

[0010] In one example of this invention, the wall of the thermally conductive via is plated with a copper layer.

[0011] In the above scheme, the thermal vias are copper-plated vias. The copper layer on the via wall can accelerate the heat conduction speed, which is beneficial to the cooling of the chip and improves the heat dissipation efficiency.

[0012] In one example of this invention, the thermally conductive layer is made of an insulating material.

[0013] In the above solution, the thermally conductive layer has good insulation properties to prevent the chip from conducting through the copper layer on the wall of the thermally conductive via and the copper block, thus avoiding affecting the normal operation of the chip.

[0014] In one example of this utility model, multiple thermally conductive vias are provided, and the multiple thermally conductive vias are distributed at equal intervals.

[0015] In the above solution, by setting multiple thermal vias to increase the contact area with the chip, the chip's heat dissipation speed can be significantly improved.

[0016] In one example of this utility model, multiple heat dissipation holes are provided, and the multiple heat dissipation holes are distributed at equal intervals.

[0017] In the above scheme, by setting multiple heat dissipation holes, the contact area with the copper block can be increased, heat conduction can be accelerated, and heat conduction efficiency can be improved.

[0018] In one example of this invention, the heat dissipation holes are filled with thermally conductive material.

[0019] In the above scheme, the heat conduction efficiency can be further improved by filling the heat dissipation holes with thermally conductive material.

[0020] In one example of this invention, the thickness of the embedded copper component is the same as the thickness of the core board.

[0021] In the above scheme, the same thickness of the embedded copper components and the core board can prevent height differences, thus avoiding difficulties in lamination and pressing.

[0022] In one example of this invention, the copper block and the thermally conductive layer are projected in the vertical direction.

[0023] In the above scheme, the copper block and the heat-conducting layer have the same size and shape on the horizontal plane, and the same size and shape as the mounting groove, to prevent gaps and ensure that the embedded copper component fits tightly with the mounting groove.

[0024] In one example of this utility model, the core board includes a substrate layer and copper foil layers disposed on opposite sides of the substrate layer.

[0025] In the above scheme, the core board is a double-sided copper-clad laminate, which includes a substrate layer made of insulating material and copper foil layers tightly attached to the upper and lower surfaces of the substrate layer.

[0026] Compared with the prior art, the beneficial effects of this utility model are as follows: This application provides a thermal via at the bottom of the chip, allowing the heat generated by the chip to be directly transferred to the buried copper assembly. This eliminates the low thermal conductivity problem caused by the adhesive layer material, improves the heat conduction rate, and accelerates the chip's heat dissipation. In addition, a heat dissipation hole is provided at the bottom of the copper block, which can improve the low thermal conductivity of the second adhesive layer and facilitate the heat conduction from the copper block to the bottom of the circuit board. As can be seen from the above, by providing thermal vias and heat dissipation holes on the upper and lower sides of the buried copper assembly, the overall heat dissipation efficiency can be effectively improved, which is beneficial to reducing the chip temperature. This application fills the gap between the copper block and the first adhesive layer by setting a heat-conducting layer on the top of the copper block, preventing gaps from appearing between the copper block and the first adhesive layer due to processing errors. This ensures the reliability of heat conduction and the normal operation of the pressing process. In addition, the heat-conducting layer can disperse the heat transferred through the heat-conducting vias, making the heat more evenly transferred to the top surface of the copper block, which helps the copper block to conduct heat more efficiently and improves heat dissipation efficiency. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a stacked diagram of a multilayer circuit board with buried copper structure according to an embodiment.

[0029] Explanation of the reference numerals in the figure: 1-Circuit board body; 11-First copper layer; 12-First adhesive layer; 13-Core board; 131-Substrate layer; 132-Copper foil layer; 133-Mounting groove; 14-Second adhesive layer; 141-Heat dissipation hole; 15-Second copper layer; 16-Thermal conductive via; 2-Buried copper assembly; 21-Copper block; 22-Thermal conductive layer; 3-Chip. Detailed Implementation

[0030] To facilitate understanding of this invention, a more comprehensive description will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the invention. However, this invention can be implemented in many different forms and is not limited to the embodiments described herein. Example 1

[0031] Please refer to Figure 1A high thermal conductivity multilayer circuit board buried copper structure includes a circuit board body 1, a buried copper assembly 2 disposed inside the circuit board body 1, and a chip 3 disposed on the top of the circuit board body 1. The circuit board body 1 includes a first copper layer 11, a first adhesive layer 12, a core board 13, a second adhesive layer 14, and a second copper layer 15 stacked from top to bottom. The core board 13 has a mounting groove 133 that runs through the thickness direction. A thermally conductive via 16 is provided above the mounting groove 133. The thermally conductive via 16 runs through the first copper layer 11 and the first adhesive layer 12 along the thickness direction. The second adhesive layer 14 has a heat dissipation hole 141 located below the mounting groove 133. The buried copper assembly 2 is disposed in the mounting groove 133. The buried copper assembly 2 includes a copper block 21 and a thermally conductive layer 22 disposed on top of the copper block 21. The upper and lower ends of the thermally conductive via 16 are respectively connected to the bottom surface of the chip 3 and the thermally conductive layer 22. The upper and lower ends of the heat dissipation hole 141 are respectively connected to the bottom surface of the copper block 21 and the second copper layer 15.

[0032] The heat-conducting layer 22 is made of a material with good thermal conductivity. The heat generated by the chip 3 during operation can be transferred to the heat-conducting layer 22 through the heat-conducting via 16 below it. The heat-conducting layer 22 then evenly transfers the heat to the copper block 21. Subsequently, the heat is conducted to the back of the circuit board body 1 through the heat dissipation holes 141 below the copper block 21, thus achieving heat dissipation for the chip 3. Since the adhesive layer in the circuit board is usually made of PP sheet, which has low thermal conductivity and high thermal resistance, this application avoids the influence of the low thermal conductivity of the adhesive layer by transferring heat through the heat-conducting via 16, improving the heat conduction rate and facilitating rapid heat dissipation of the chip 3, thereby improving heat dissipation efficiency. Furthermore, the second adhesive layer 14 below the copper block 21 has heat dissipation holes 141, which allow heat to be transferred through the heat-conducting via 16. The second adhesive layer 14 has heat dissipation holes 141, which improves the thermal conductivity of the second adhesive layer 14. This helps to conduct and dissipate heat from the copper block 21 to the bottom surface of the circuit board more efficiently, preventing heat buildup inside. In addition, during the lamination process, the thermally conductive layer 22 on the copper block 21 can fill the gap between the copper block 21 and the first adhesive layer 12, preventing gaps from appearing between the copper block 21 and the first adhesive layer 12 due to processing errors. This ensures the reliability of heat conduction and the normal operation of the lamination process. Furthermore, the thermally conductive layer 22 can disperse the heat transferred through the thermally conductive vias 16, making the heat more evenly transferred to the top surface of the copper block 21. This helps the copper block 21 conduct heat more efficiently and improves heat dissipation efficiency.

[0033] Preferably, the thermally conductive layer 22 is made of thermally conductive silicone. In addition, other insulating materials with high thermal conductivity, such as silicone grease, can also be used.

[0034] Preferably, the first adhesive layer 12 and the second adhesive layer 14 are prepreg sheets (PP sheets).

[0035] like Figure 1As shown, the diameter of the thermal via 16 gradually decreases from top to bottom. The larger diameter end of the thermal via 16 at the top contacts the bottom surface of the chip 3, which is beneficial for quickly receiving heat from the chip 3 and accelerating the heat dissipation of the chip 3. As the diameter of the thermal via 16 decreases downward, the speed at which heat is conducted towards the buried copper component 2 can be gradually increased, thereby improving the heat conduction speed.

[0036] Preferably, the thermal via 16 is a copper-plated via with a copper layer plated on its inner wall. The copper layer on the via wall can further accelerate the heat conduction speed, which is beneficial to the cooling of chip 3 and improves heat dissipation efficiency.

[0037] Preferably, the thermally conductive layer 22 is made of an insulating material to ensure good insulation, thereby preventing the chip 3 from conducting through the copper layer on the wall of the thermally conductive via 16 to the copper block 21, thus avoiding affecting the normal operation of the chip 3.

[0038] Please refer to Figure 1 Multiple thermal vias 16 are provided, and the multiple thermal vias 16 are distributed at equal intervals. By providing multiple thermal vias 16, the contact area with the chip 3 is increased, which can significantly improve the heat dissipation speed of the chip 3.

[0039] Please continue to refer to Figure 1 Multiple heat dissipation holes 141 are provided, and the multiple heat dissipation holes 141 are distributed at equal intervals. By providing multiple heat dissipation holes 141, the contact area with the copper block 21 can be increased, the heat conduction can be accelerated, and the heat conduction efficiency can be improved.

[0040] To further enhance heat dissipation, the heat dissipation holes 141 are filled with thermally conductive material (shown in the figure), which can effectively improve the heat conduction rate and help heat be quickly transferred to the bottom surface of the circuit board body 1, avoiding accumulation inside the circuit board.

[0041] In other embodiments, copper can be plated on the wall of the heat dissipation hole 141 to make the heat dissipation hole 141 a copper-plated hole, thereby enhancing the thermal conductivity. Of course, when plating copper, it is necessary to ensure that the copper layer on the wall of the heat dissipation hole 141 is discontinuous in the height direction to prevent conductivity and avoid affecting the normal operation of the internal circuit.

[0042] like Figure 1 As shown, the thickness of the embedded copper component 2 is the same as the thickness of the core board 13, that is, the same as the depth of the mounting groove 133, to prevent height differences and avoid difficulties in lamination and pressing.

[0043] Furthermore, the projections of the copper block 21 and the heat-conducting layer 22 in the vertical direction coincide, meaning that the copper block 21 and the heat-conducting layer 22 have the same size and shape on the horizontal plane, and the same size and shape as the mounting groove 133, to prevent any gaps between the buried copper assembly 2 and the mounting groove 133, so that the buried copper assembly 2 and the mounting groove 133 fit tightly together, ensuring a compact overall structure.

[0044] Please refer to Figure 1 The core board 13 includes a substrate layer 31 and copper foil layers 132 disposed on opposite sides of the substrate layer 31.

[0045] Specifically, the core board 13 is a double-sided copper-clad laminate, which includes a substrate and copper foil covering both sides of the substrate, namely the substrate layer 31 and the copper foil layer 132 in this embodiment. The substrate layer 31 is made of insulating material, and the copper foil layer 132 is preferably rolled copper foil. Example 2

[0046] This embodiment provides a processing and embedding process applicable to the copper embedded component 2 in Embodiment 1, mainly including the following steps: S1: The copper substrate, the second adhesive layer 14 and the second copper layer 15 are stacked together and the first pressing process is performed. S2: After laminating, exposing, developing, etching, and removing the film from the copper substrate, copper block 21 is obtained; S3: Place the prepared core board 13 with mounting groove 133 on the second adhesive layer 14, and let the copper block 21 fall into the mounting groove 133; S4: A heat-conducting layer 22 is set on the top of the copper block 21, and then the first adhesive layer 12 and the first copper foil are placed on the top surface of the core board 13 for a second pressing process to complete the embedding of the copper block 21.

[0047] In step S1, the process includes processing heat dissipation holes 141 in the second adhesive layer 14 and filling the heat dissipation holes 141 with thermally conductive material. In step S4, the process includes processing thermally conductive vias 16 on the circuit board body 1.

[0048] It should be noted that in this embodiment, the copper substrate is first laminated with the second copper layer 15, and then the copper block 21 is obtained through the processes of lamination, exposure, development, etching and film removal. This process can produce multiple copper blocks 21 at once, realizing the continuous production of embedded copper plates. Compared with the traditional process of directly processing multiple copper blocks and then embedding them one by one, it can effectively improve production efficiency and production benefits.

[0049] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0050] Furthermore, 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 or an electrical connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multilayer circuit board buried copper structure with high thermal conductivity, characterized in that, include: The circuit board body includes a first copper layer, a first adhesive layer, a core board, a second adhesive layer, and a second copper layer stacked from top to bottom. The core board has a mounting groove that extends through the thickness direction. A heat-conducting via is provided above the mounting groove. The heat-conducting via extends through the first copper layer and the first adhesive layer along the thickness direction. The second adhesive layer has heat dissipation holes located below the mounting groove. A copper-embedded assembly is disposed in the mounting groove, the copper-embedded assembly comprising a copper block and a heat-conducting layer disposed on top of the copper block; The chip is located on the top of the main body of the circuit board; The upper and lower ends of the thermally conductive via are respectively connected to the bottom surface of the chip and the thermally conductive layer, and the upper and lower ends of the heat dissipation hole are respectively connected to the bottom surface of the copper block and the second copper layer.

2. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The diameter of the heat-conducting via gradually decreases from top to bottom.

3. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The walls of the thermally conductive via are plated with a copper layer.

4. The high thermal conductivity multilayer circuit board buried copper structure according to claim 3, characterized in that, The thermally conductive layer is made of an insulating material.

5. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, Multiple thermally conductive vias are provided, and the multiple thermally conductive vias are distributed at equal intervals.

6. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The heat dissipation holes are provided in multiple ways, and the multiple heat dissipation holes are distributed at equal intervals.

7. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The heat dissipation holes are filled with thermally conductive material.

8. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The thickness of the embedded copper component is the same as the thickness of the core board.

9. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The projection of the copper block and the heat-conducting layer in the vertical direction coincides.

10. The high thermal conductivity multilayer circuit board buried copper structure according to claim 1, characterized in that, The core board includes a substrate layer and copper foil layers disposed on opposite sides of the substrate layer.

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