A multilayer circuit board with inner layer interconnection

Abstract

This utility model relates to a multilayer circuit board with internal interconnection. By providing heat dissipation vias connecting the power layer to the outer side of the bottom signal layer, and placing heat-conducting pillars inside the vias, which are connected to heat-conducting pads on the lower end face of the bottom signal layer, heat inside the circuit board is rapidly conducted to the heat-conducting pads. Furthermore, by providing mounting grooves at the bottom of the heat-conducting pads, housing micro heat pipes, and attaching heat sinks to the sidewalls of the multilayer PCB board, with heat dissipation fins on the outside of the heat sinks, and connecting the two ends of the micro heat pipes to the heat-conducting pads and the heat sink respectively, heat from the heat-conducting pads is rapidly transferred to the heat sink for quick dissipation. This significantly improves the overall heat dissipation efficiency of the circuit board, effectively reduces the temperature of the circuit board under high-power operating conditions, and enhances the stability and reliability of the circuit board.

Description

Technical Field

[0001] This utility model relates to the field of printed circuit board technology, and in particular to a multilayer circuit board with internal interconnection. Background Technology

[0002] Printed circuit boards, also known as PCBs, are crucial providers of electrical connections for electronic components. To maximize the area available for wiring, multilayer printed circuit boards utilize more single-sided or double-sided wiring boards. Such multilayer printed circuit boards typically use one double-sided wiring board as the inner layer and two single-sided wiring boards as the outer layers; or two double-sided wiring boards as the inner layers and two other single-sided wiring boards as the outer layers. These different types of wiring boards are alternately combined using positioning systems and insulating adhesives, and the conductive patterns are interconnected according to design requirements.

[0003] However, existing multilayer printed circuit boards with internal interconnects tend to generate a lot of heat during use. Because this heat cannot be dissipated effectively and promptly, it can easily damage internal electronic components. This heat dissipation problem not only affects the performance of the circuit board but also significantly reduces its lifespan. Utility Model Content

[0004] Therefore, it is necessary to provide a multilayer circuit board with inner layer interconnection.

[0005] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A multilayer circuit board with inner layer interconnection includes a multilayer PCB board body. The multilayer PCB board body includes a top signal layer, a ground layer A, a signal layer, a power layer, a ground layer B, and a bottom signal layer stacked from top to bottom. Blind vias are provided between the top signal layer and the ground layer A, and between the ground layer B and the bottom signal layer. Buried vias are provided between the ground layer A and the ground layer B. A thermally conductive pad is provided at the bottom of the bottom signal layer. A plurality of thermally conductive vias communicating to the bottom of the bottom signal layer are provided on the ground layer B. The thermally conductive vias are arranged in an array. A thermally conductive pillar is provided in the thermally conductive via. The lower end of the thermally conductive pillar communicates with the thermally conductive pad. A mounting groove is provided at the bottom of the thermally conductive pad. A micro heat pipe is provided in the mounting groove. The first end of the micro heat pipe is connected to the thermally conductive pad, and the second end extends to the outside of the thermally conductive pad. A heat sink is attached to the outside of the multilayer PCB board. The heat sink is connected to the second end of the micro heat pipe.

[0006] In one embodiment, the heat-conducting column is a hollow cylindrical metal column, and the outer wall of the heat-conducting column is fixedly connected to the heat-conducting through hole by thermally conductive adhesive.

[0007] In one embodiment, the diameter of the thermally conductive via is 0.3–0.5 mm, and the spacing between the vias is 1–2 mm.

[0008] In one embodiment, the micro heat pipe is tightly attached to the mounting groove using highly thermally conductive silicone grease.

[0009] In one embodiment, a thermally conductive silicone pad is provided at the connection between the second end of the micro heat pipe and the heat sink.

[0010] In one embodiment, the heat sink is an aluminum heat sink, and the side of the heat sink away from the multilayer PCB board is provided with multiple heat dissipation fins, which are arranged in parallel at equal intervals.

[0011] In one embodiment, the heat sink is fixedly connected to the sidewall of the multilayer PCB board by thermally conductive adhesive.

[0012] In one embodiment, the inner walls of both the buried via and the blind via are provided with a copper plating layer, the copper plating layer covers the inner walls of the buried via and the blind via, and the middle of the blind via and the buried via is filled with epoxy resin.

[0013] In one embodiment, an insulating and thermally conductive layer is provided between the signal layer and the power layer, and one end of the insulating and thermally conductive layer is connected to the heat sink.

[0014] In one embodiment, the ground layer A is provided with a heat dissipation hole that connects to the top signal layer, and the heat dissipation hole is provided with a heat-conducting pin for conducting heat.

[0015] The beneficial effects of this utility model are as follows: This utility model provides a multilayer circuit board with internal interconnection. By setting heat dissipation vias on the power layer to the outside of the bottom signal layer, and setting heat-conducting pillars inside the heat dissipation vias, the heat-conducting pillars are connected to heat dissipation pads set on the lower end face of the bottom signal layer, thereby quickly conducting heat inside the circuit board to the heat-conducting pads. By setting mounting grooves at the bottom of the heat-conducting pads, setting micro heat pipes in the mounting grooves, and attaching heat sinks to the side walls of the multilayer PCB board, the heat sinks are provided with heat dissipation fins on the outside of the heat sinks. The two ends of the micro heat pipes are connected to the heat-conducting pads and the heat sinks respectively, the heat on the heat-conducting pads is quickly transferred to the heat sinks and quickly dissipated, thereby greatly improving the overall heat dissipation efficiency of the circuit board, effectively reducing the temperature of the circuit board under high power operation, and improving the stability and reliability of the circuit board. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is a schematic diagram of the structure of a multilayer circuit board with inner layer interconnection as an embodiment;

[0018] Figure 2 This is a schematic diagram of the thermal pads and heat sink of a multilayer circuit board with inner layer interconnection, according to one embodiment.

[0019] In the attached diagram, 10 is a multilayer circuit board with inner layer interconnections; 100 is the multilayer PCB board body; 110 is the top signal layer; 120 is the ground layer A; 121 is a heat dissipation hole; 122 is a thermal conductive pin; 130 is a signal layer; 131 is an insulating and thermally conductive layer; 140 is a power layer; 150 is a ground layer B; 160 is the bottom signal layer; 170 is a blind via; 180 is a buried via; 200 is a thermally conductive via; 210 is a thermally conductive pillar; 300 is a thermally conductive pad; 310 is a mounting slot; 400 is a miniature heat pipe; 500 is a heat sink; and 510 is a heat dissipation fin. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments of the present invention can be combined with each other. The technical solutions of the present invention will be further described below with reference to the accompanying drawings of the embodiments. The present invention is not limited to the specific embodiments described below.

[0021] It should be understood that the same or similar reference numerals in the accompanying drawings of the embodiments correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "front," "rear," "left," "right," "top," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms describing positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0022] In one embodiment, such as Figure 1 and Figure 2As shown, a multilayer circuit board 10 with inner layer interconnection includes a multilayer PCB body 100. The multilayer PCB body 100 includes a top signal layer 110, a ground layer A120, a signal layer 130, a power layer 140, a ground layer B150, and a bottom signal layer 160 stacked from top to bottom. Blind vias 170 are provided between the top signal layer 110 and the ground layer A120, and between the ground layer B150 and the bottom signal layer 160. Buried vias 180 are provided between the ground layer A120 and the ground layer B150. A thermal pad 300 is provided at the bottom of the bottom signal layer 160. The system includes multiple thermal vias 200 that connect to the bottom of the bottom signal layer 160, arranged in an array. Each thermal via 200 contains a thermal pillar 210, the lower end of which communicates with a thermal pad 300. The bottom of the thermal pad 300 has a mounting groove 310, within which a miniature heat pipe 400 is installed. The first end of the miniature heat pipe 400 is connected to the thermal pad 300, and the second end extends outward from the thermal pad 300. A heat sink 500 is mounted on the outer side of the multilayer PCB, and the heat sink 500 is connected to the second end of the miniature heat pipe 400.

[0023] In this embodiment, the multilayer PCB board body 100 is composed of a top signal layer 110, a ground layer A120, a signal layer 130, a power layer 140, a ground layer B150, and a bottom signal layer 160 stacked sequentially. There is an insulating and thermally conductive layer 131 between the signal layer 130 and the signal layer 140, and the other layers are separated by PP (polypropylene) spacers. Copper foil layers are provided at the top of the top signal layer and the bottom of the bottom signal layer. By setting blind vias 170 between the top signal layer 110 and the ground layer A120, between the ground layer B150 and the bottom signal layer 160, and between the ground layer A120 and the ground layer B150, and by setting buried vias 180 between the ground layer A120 and the ground layer B150, wiring between different layers is connected, so that the layers inside the circuit board can be conductive. Multiple thermal vias 200 are provided on the ground layer B150, and the thermal vias 200 are distributed in an array, extending from the bottom signal layer 160 to its lower end face. Thermal pillars 210 are provided inside the thermal vias 200 to transfer heat from the inner layer to the outer layer of the circuit board. Thermal pads 300 are provided at the bottom of the bottom signal layer 160, and the thermal pads 300 are connected to the lower ends of the thermal pillars 210, thereby effectively dissipating the heat generated inside the circuit board. The heat is conducted to the thermal pad 300. A mounting groove 310 is provided at the bottom of the thermal pad 300. A miniature heat pipe 400 is provided in the mounting groove 310. The first end of the miniature heat pipe 400 is tightly connected to the thermal pad 300, and the second end extends to the outside of the thermal pad 300 and is connected to the heat sink 500 mounted on the side wall of the circuit board. The heat absorbed by the thermal pad 300 is quickly conducted to the heat sink 500 through the miniature heat pipe 400, so as to achieve efficient heat conduction and heat dissipation.

[0024] In one embodiment, the heat-conducting pillar 210 is a hollow cylindrical metal column, and the outer wall of the heat-conducting pillar 210 is fixedly connected to the heat-conducting via 200 by thermally conductive adhesive. The diameter of the heat-conducting via 200 is 0.3-0.5 mm, and the spacing between the holes is 1-2 mm. Specifically, in this embodiment, the diameter of the heat-conducting via 200 is 0.5 mm, the distance between each hole is 1.5 mm, and multiple heat-conducting vias 200 are evenly distributed in an array. Each heat-conducting via 200 has an independent heat-conducting pillar 210 inside. The heat-conducting pillar 210 is a hollow cylindrical alumina column with good thermal conductivity and insulation. The outer wall of the heat-conducting pillar 210 is fixedly connected to the inner wall of the heat-conducting via 200 by thermally conductive adhesive. The thermally conductive adhesive can effectively conduct heat from the circuit board to the heat-conducting pillar 210, and at the same time, the thermally conductive adhesive has insulation properties to avoid electrical short circuits between the heat-conducting pillar 210 and other parts of the circuit board.

[0025] In one embodiment, the micro heat pipe 400 is tightly attached to the mounting groove 310 using high thermal conductivity silicone grease; a thermally conductive silicone pad is provided at the connection between the second end of the micro heat pipe 400 and the heat sink 500. Specifically, there are two mounting grooves 310 at the bottom of the thermal pad 300, respectively located on both sides of the lower end face of the thermal pad 300, avoiding the wiring area on the bottom signal layer 160. The shape of each mounting groove 310 matches the shape of the micro heat pipe 400, so that the micro heat pipe 400 can be tightly embedded in the mounting groove 310. The number of miniature heat pipes 400 is the same as the number of mounting slots 310. Each miniature heat pipe 400 is tightly attached to the inside of its corresponding mounting slot 310 with high thermal conductivity silicone grease to ensure heat conduction efficiency. A copper foil transition layer is provided between the first end of the miniature heat pipe 400 and the thermal pad 300. The copper foil transition layer can further improve the heat conduction efficiency between the thermal pad 300 and the miniature heat pipe 400, and at the same time enhance the structural stability between the two. A thermally conductive silicone pad is provided at the connection between the second end of the miniature heat pipe 400 and the heat sink 500 to separate the second end from the heat sink 500 and reduce the risk of short circuit. Through the phase change process inside the miniature heat pipe 400, that is, after the end of the miniature heat pipe 400 near the thermal pad 300 is heated, the internal liquid evaporates, the vapor flows to the other end of the miniature heat pipe 400 and condenses to release heat. The condensed liquid flows back to the evaporation end through the capillary structure to form a cycle, thereby quickly transferring heat from the thermal pad 300 to the heat sink 500, realizing the efficient heat removal inside the circuit board. In this embodiment, the micro heat pipe is a common device on the market and is existing technology, so it will not be described in detail here.

[0026] In one embodiment, the heat sink 500 is an aluminum heat sink, and the side of the heat sink 500 away from the multilayer PCB board has multiple heat dissipation fins 510, which are arranged in parallel at equal intervals. Specifically, the heat sink 500 in this embodiment is made of aluminum, which has excellent thermal conductivity and light weight, effectively reducing the thermal resistance of the overall structure; the heat sink 500 has multiple heat dissipation fins 510 on the side away from the multilayer PCB board, which are arranged in parallel at equal intervals to increase the heat dissipation area. Heat is quickly dissipated to the surrounding environment through air convection between the heat dissipation fins 510, thereby significantly improving heat dissipation efficiency.

[0027] In one embodiment, the heat sink 500 is fixedly connected to the sidewall of the multilayer PCB board via thermally conductive adhesive. Specifically, the sidewall of the heat sink 500 is fixedly connected to the sidewall of the multilayer PCB board via thermally conductive adhesive, and the heat on the circuit board can also be directly transferred to the heat sink 500 through the thermally conductive adhesive, further improving the overall heat dissipation efficiency.

[0028] In one embodiment, the inner walls of both the buried via 180 and the blind via 170 are plated with copper, which covers the inner walls of the buried via 180 and the blind via 170. The middle of the blind via 170 and the buried via 180 is filled with epoxy resin. Specifically, a copper layer is electroplated on the wall of both the buried via 180 and the blind via 170, making the insulated wall conductive and forming a complete conductive path to achieve electrical connection between inner layer circuits. Simultaneously, the epoxy resin filling in the middle of the blind via 170 and the buried via 180 enhances their structural strength, prevents the copper layer on the wall from breaking during subsequent processing, avoids breakage of the conductive path due to copper layer breakage, and thus improves the reliability of the circuit board.

[0029] In one embodiment, an insulating thermally conductive layer 131 is provided between the signal layer and the power layer, and one end of the insulating thermally conductive layer 131 is connected to the heat sink. Specifically, in order to enhance the heat conduction efficiency inside the circuit board, an insulating thermally conductive layer 131 is provided between the signal layer and the power layer. This insulating thermally conductive layer 131 is made of alumina ceramic matrix composite material, which has excellent thermal conductivity and good electrical insulation. The upper and lower end faces of the insulating thermally conductive layer 131 are in close contact with the signal layer and the power layer, respectively, to achieve rapid heat conduction while effectively blocking the direct flow of current. One end of the insulating thermally conductive layer 131 is connected to the heat sink, thereby rapidly transferring the heat generated by the signal layer and the power layer to the heat sink, further improving the overall heat dissipation efficiency.

[0030] In one embodiment, the ground layer A is provided with a heat dissipation hole 121 connecting to the top signal layer, and a heat-conducting pin 122 for conducting heat is provided inside the heat dissipation hole 121. Specifically, a heat dissipation hole 121 connecting to the top signal layer is provided on the ground layer A, and a heat-conducting pin 122 made of alumina is provided inside the heat dissipation hole 121. The outer wall of the heat-conducting pin 122 is in close contact with the inner wall of the heat dissipation hole 121 to achieve a good heat conduction effect, thereby conducting the heat of the upper layer of the circuit board to the outside through the heat-conducting pin 122, effectively reducing the risk of local overheating of the circuit board.

[0031] Compared with the prior art, the present invention has at least the following advantages:

[0032] This invention provides a multilayer circuit board with internal interconnection. By providing heat dissipation vias connecting the power layer to the outer side of the bottom signal layer, and placing heat-conducting pillars inside the vias, which are connected to heat-conducting pads on the lower end face of the bottom signal layer, heat inside the circuit board is rapidly conducted to the heat-conducting pads. A mounting groove is provided at the bottom of the heat-conducting pad, containing a micro heat pipe. A heat sink is attached to the side wall of the multilayer PCB board, with heat dissipation fins on its exterior. The two ends of the micro heat pipes are connected to the heat-conducting pads and the heat sink, respectively, rapidly transferring heat from the heat-conducting pads to the heat sink for quick dissipation, thus significantly improving the overall heat dissipation efficiency of the circuit board. Furthermore, an insulating conductive layer is provided between the power layer and the signal layer, and heat dissipation holes are provided on the ground layer A to enhance heat conduction. Heat-conducting pins are placed inside the heat dissipation holes, further improving heat transfer efficiency. This effectively reduces the temperature of the circuit board under high-power operating conditions, improving the stability and reliability of the circuit board.

[0033] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A multilayer circuit board with inner layer interconnection, comprising a multilayer PCB board body, characterized in that, The multilayer PCB board body includes, from top to bottom, a top signal layer, a ground layer A, a signal layer, a power layer, a ground layer B, and a bottom signal layer. Blind vias are provided between the top signal layer and ground layer A, and between ground layer B and the bottom signal layer. Buried vias are provided between ground layer A and ground layer B. A thermally conductive pad is provided at the bottom of the bottom signal layer. Multiple thermally conductive vias connected to the bottom of the bottom signal layer are provided on ground layer B, and these vias are arranged in an array. Thermally conductive pillars are provided within the thermally conductive vias, with their lower ends connected to the thermally conductive pads. A mounting groove is provided at the bottom of the thermally conductive pads, and a micro heat pipe is provided within the mounting groove. A first end of the micro heat pipe is connected to the thermally conductive pad, and a second end extends beyond the outer side of the thermally conductive pad. A heat sink is mounted on the outer side of the multilayer PCB board, and the heat sink is connected to the second end of the micro heat pipe.

2. The multilayer circuit board with inner layer interconnection according to claim 1, characterized in that, The heat-conducting column is a hollow cylindrical metal column, and the outer wall of the heat-conducting column is fixedly connected to the heat-conducting through hole by heat-conducting adhesive.

3. A multilayer circuit board with inner layer interconnection according to claim 2, characterized in that, The diameter of the heat-conducting via is 0.3–0.5 mm, and the spacing between the vias is 1–2 mm.

4. A multilayer circuit board with inner layer interconnection according to claim 1, characterized in that, The micro heat pipe is tightly attached to the mounting groove using highly thermally conductive silicone grease.

5. A multilayer circuit board with inner layer interconnection according to claim 4, characterized in that, A thermally conductive silicone pad is provided at the connection between the second end of the micro heat pipe and the heat sink.

6. A multilayer circuit board with inner layer interconnection according to claim 1, characterized in that, The heat sink is an aluminum heat sink, and multiple heat dissipation fins are provided on the side of the heat sink away from the multilayer PCB board. The heat dissipation fins are arranged in parallel at equal intervals.

7. A multilayer circuit board with inner layer interconnection according to claim 6, characterized in that, The heat sink is fixedly connected to the side wall of the multilayer PCB board by thermally conductive adhesive.

8. A multilayer circuit board with inner layer interconnection according to claim 1, characterized in that, The inner walls of both the buried and blind vias are provided with copper plating layers, which cover the inner walls of the buried and blind vias. The middle of the blind and buried vias is filled with epoxy resin.

9. A multilayer circuit board with inner layer interconnection according to claim 7, characterized in that, An insulating and heat-conducting layer is provided between the signal layer and the power layer, and one end of the insulating and heat-conducting layer is connected to the heat sink.

10. A multilayer circuit board with inner layer interconnection according to claim 1, characterized in that, The grounding layer A is provided with a heat dissipation hole that connects to the top signal layer, and the heat dissipation hole is provided with a heat-conducting pin for conducting heat.

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