A controller circuit board for a street lamp based on a nano heat dissipation material and a preparation method thereof

Abstract

The application discloses a kind of controller circuit board based on nano heat dissipation material for street lamp and preparation method thereof, belong to circuit board production manufacturing technical field.The circuit board includes substrate layer, nano heat dissipation interlayer, conductive circuit layer, heat conduction via, embedded power device cavity and edge heat conduction boss, and the nano heat dissipation interlayer is formed by boron nitride nanosheet, nitrogen-doped carbon nanotube and ternary hybrid filler of nano silver line and insulation polymer composition;Preparation method includes nano heat dissipation slurry preparation, interlayer forming, cavity preparation, circuit and via formation, edge heat conduction structure integration and packaging test steps.The application is synergized with shell through multidimensional heat conduction path and radiates heat, effectively reduces power device temperature rise, adopts fanless passive heat dissipation to adapt to outdoor harsh working conditions, compatible with multi-module integration, process is easy to mass production, can delay component aging, prolong the service life of street lamp controller.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and in particular to a controller circuit board for streetlights based on nano heat dissipation materials and its preparation method. Background Technology

[0002] As the core control unit of a street lighting system, a street light controller typically includes a core control module, a dimming drive module, a wireless communication module (such as LoRa, NB-IoT, 4G Cat.1, etc.), and a power management module. With the increasing popularity of smart street lights, the integration level of controllers is constantly improving. Moreover, street light controllers are usually installed in a sealed housing and exposed to high outdoor temperatures and direct sunlight, resulting in extremely poor heat dissipation conditions.

[0003] The existing street light controllers mainly have the following technical problems: 1. Simple heat dissipation structure and high thermal resistance: Traditional street light controllers use a passive heat dissipation method with an aluminum housing and heat sink fins. There are thermal pads or air gaps between the circuit board and the housing, resulting in high contact thermal resistance and difficulty in effectively dissipating heat. Some solutions use built-in cooling fans, but the fans are prone to failure due to dust and moisture intrusion, and their reliability cannot meet the requirement of a service life of more than 10 years for street lights.

[0004] 2. Insufficient thermal conductivity of circuit board substrate: Conventional street light controller circuit boards use FR-4 substrates (thermal conductivity 0.3~0.5W / m·K) or aluminum substrates (thermal conductivity 1~3W / m·K), which are far from meeting the heat dissipation requirements of high power density controllers. When the controller operates in a high-temperature, enclosed environment for a long time, the junction temperature of power devices such as MOSFETs and integrated circuits rises, leading to a shortened controller lifespan and an increased failure rate.

[0005] 3. Lack of systematic thermal design for street lighting applications: Existing patents such as CN211267214U disclose a high-pressure sodium lamp street light controller based on LoRa technology, but do not involve heat dissipation module design. CN210137475U discloses a smart street light node controller that uses active cooling with a fan, but there is a risk of dust and water ingress in outdoor enclosed environments. No systematic solution has yet been found in the existing technology that addresses the heat dissipation problem of street light controllers from the perspective of the internal structure of the circuit board. Summary of the Invention

[0006] The purpose of this invention is to provide a street light controller circuit board based on nano heat dissipation materials and its preparation method. Targeting the characteristics of street light controllers operating in outdoor high temperatures, in a sealed environment, and with a long lifespan, the invention achieves rapid heat dissipation and uniform distribution within the controller through a synergistic heat dissipation design of the internal nano heat dissipation layer and the casing, thereby reducing the junction temperature of power devices and improving the reliability and service life of the street light controller.

[0007] To achieve the above objectives, the present invention provides a street light controller circuit board based on nano heat dissipation materials, comprising a base layer, a nano heat dissipation interlayer disposed above the base layer, a conductive circuit layer disposed above the nano heat dissipation interlayer, a plurality of thermally conductive vias penetrating the conductive circuit layer and the nano heat dissipation interlayer and extending to the base layer, an embedded power device cavity disposed below the conductive circuit layer and in direct contact with the nano heat dissipation interlayer, and thermally conductive bosses disposed on the edge of the circuit board for contacting the inner wall of the metal housing of the street light controller.

[0008] Preferably, the nano-heat dissipation interlayer comprises a ternary hybrid filler and an insulating polymer matrix; the ternary hybrid filler specifically comprises boron nitride nanosheets (BNNSs), nitrogen-doped carbon nanotubes (N-CNTs), and silver nanowires (Ag NWs).

[0009] Preferably, the conductive circuit layer includes the core control circuit, pulse width modulation (PWM) dimming circuit, power output circuit, wireless communication module circuit, and power management circuit required by the street light controller. The wireless communication module is selected from a long-range LoRa module, a narrowband Internet of Things (NB-IoT) module, and a 4G Cat.1 module.

[0010] Preferably, the mass fraction of the ternary hybrid filler is 30%~50%, and the mass ratio of BNNSs, N-CNTs and Ag NWs is (6~8):(1~2):(1~2).

[0011] Preferably, the in-plane thermal conductivity of the nano heat dissipation interlayer is ≥18W / m·K, the vertical thermal conductivity is ≥6W / m·K, and the breakdown voltage is ≥3kV.

[0012] Preferably, the cavity of the embedded power device is filled with a nano-thermal conductive gel with a thermal conductivity ≥5W / m·K. The cavity of the embedded power device is used to house the power chip of the street light controller. The power chip includes a power metal-oxide-semiconductor field-effect transistor (MOSFET), a rectifier bridge, and a DC-DC power supply module.

[0013] Preferably, when the circuit board is installed inside the metal housing of the street light controller, the contact surface between the thermally conductive boss and the inner wall of the controller's metal housing is coated with thermally conductive silicone grease or nano-thermal conductive gel to form a low thermal resistance thermal conduction path.

[0014] This invention also provides a method for preparing the above-mentioned controller circuit board for streetlights based on nano-heat dissipation materials, comprising the following steps: S1. Disperse BNNSs, N-CNTs and Ag NWs in an organic solvent containing polyvinylpyrrolidone at a mass ratio of (6~8):(1~2):(1~2), and ultrasonically disperse for 2~3 hours to obtain a nanofiller mixture with a solid content of 25%~35%; then add a high-temperature resistant epoxy resin matrix and a latent curing agent, and grind it 3~5 times with a three-roll mill to obtain a special nano heat dissipation slurry for street light controllers with a viscosity of 3000~6000 cP (25℃); S2. The nano heat dissipation paste is coated on the substrate layer by screen printing or slit coating, with the thickness controlled at 80~150μm. After vacuum degassing, a stepped temperature curing process is adopted: 80℃ / 1h→120℃ / 1h→160℃ / 2h to obtain a nano heat dissipation interlayer with an anisotropic thermal conductive network structure. S3. An embedded power device cavity is formed in the nano heat dissipation interlayer by laser ablation or mechanical milling. The cavity depth is 60% to 90% of the thickness of the nano heat dissipation interlayer. Nano silver conductive adhesive is coated on the inner wall of the cavity, the power chip is placed at the bottom of the cavity, and then nano thermal conductive gel is filled. S4. A conductive circuit layer with a thickness of 35~70μm is formed on the surface of the nano heat dissipation interlayer by using copper cladding or sputtering copper seed layer combined with electroplating to thicken the layer. The conductive circuit layer contains the functional circuits required by the street light controller. Micro-vias with a diameter of Ф0.2~0.5mm are drilled using a CO2 laser, and after plasma cleaning, they are filled with nano thermal conductive gel. Electroplating is performed again to make the two ends of the micro-vias conductive with the conductive circuit layer, forming vertical thermal conductive vias. S5. Process thermally conductive bosses on the edge of the circuit board. Coat the surface of the thermally conductive bosses with thermally conductive silicone grease or nano thermally conductive gel to ensure that when the circuit board is installed in the metal housing of the street light controller, the thermally conductive bosses make contact with the inner wall of the housing, so as to realize direct heat conduction between the circuit board and the housing. S6. Coat the surface of the circuit board with thermally conductive solder resist ink, and perform functional testing and high-temperature aging testing on the finished circuit board after heat curing.

[0015] The present invention also provides a street light controller, comprising the above-mentioned street light controller circuit board based on nano heat dissipation material, and a street light controller metal housing that houses the circuit board. The outer surface of the controller metal housing is provided with heat dissipation fins. The heat-conducting protrusions on the edge of the circuit board are in interference fit contact with the inner wall of the controller metal housing to form a heat conduction path, and the contact surface is coated with thermal grease or nano thermal conductive gel.

[0016] Therefore, the present invention, employing the above-mentioned controller circuit board for streetlights based on nano-heat dissipation materials and its preparation method, has the following beneficial effects: 1) Reduced internal temperature rise of street light controller: The in-plane + vertical dual-channel heat conduction structure constructed by the nano heat dissipation sandwich layer, together with the heat conduction via and the embedded device cavity, reduces the junction temperature of the key power devices of the street light controller compared with the traditional FR-4 substrate and the traditional aluminum substrate, meeting the reliable operation requirements of the street light controller in outdoor high temperature environment.

[0017] 2) Suitable for special working conditions of street light controllers: In view of the outdoor enclosed and long-life operation characteristics of street light controllers, a fanless passive heat dissipation design is adopted to avoid the reliability risks of active fan heat dissipation solutions in outdoor environments; the edge heat conduction structure allows the heat of the circuit board to be directly conducted to the metal shell, and the heat dissipation fins of the shell are used to dissipate heat to the environment.

[0018] 3) Compatible with multi-module integration of street light controllers: The circuit board integrates multiple functional circuits such as the core control module, PWM dimming driver, LORA / NB-IoT module, and power management module to meet the high integration requirements of smart street lights for controllers.

[0019] 4) Compatible with existing printed circuit board (PCB) processes: The preparation method of this invention is compatible with standard PCB processes, requires no special equipment, and is suitable for mass production.

[0020] 5) Extend the service life of street light controllers: By reducing the operating junction temperature of power devices, the aging rate of electronic components is slowed down.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the layer structure of the circuit board for a street light controller based on nano heat dissipation material according to the present invention; Figure 2 This is a process flow diagram of the fabrication process of the controller circuit board for streetlights based on nano heat dissipation materials according to the present invention; Figure 3 These are microscopic images of the nano heat dissipation material of the present invention: (a) is a SEM image of nitrogen-doped carbon nanotubes (N-CNTs); (b) is a TEM image of nitrogen-doped carbon nanotubes (N-CNTs); and (c) is a SEM image of boron nitride nanosheets (BNNSs). Figure 4 A comparison of the thermal conductivity of nano-heat dissipation films with different filler systems; Figure 5 The temperature test curve of the LED smart street light controller circuit board in an embodiment of the present invention; Figure 6 This is a 40°C temperature test curve of the circuit board of the intelligent controller for the high-pressure sodium lamp in an embodiment of the present invention. Figure 7The temperature test curve at 50°C is shown for the circuit board of the intelligent controller for the high-pressure sodium lamp in an embodiment of the present invention.

[0023] Figure Labels 1. Base layer; 2. Nano heat dissipation interlayer; 3. Conductive circuit layer; 4. Thermally conductive via; 5. Embedded power device cavity; 6. Power chip; 7. Nano thermally conductive gel; 8. Thermally conductive boss; 9. Controller metal housing; 10. Housing heat dissipation fins. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] Example 1 This invention provides a controller circuit board for streetlights based on nano-heat dissipation materials, the structure of which is as follows: Figure 1 As shown, it includes a base layer 1, which is a thermally modified FR-4 composite material or a metal substrate, preferably a high thermal conductivity aluminum substrate or a copper substrate. The back side of the base layer 1 is in direct contact with the metal housing 9 of the street light controller via thermally conductive silicone grease.

[0027] A nano-heat dissipation interlayer 2 is disposed above the substrate layer 1. The nano-heat dissipation interlayer 2 is composed of a three-dimensional network ternary hybrid filler and an insulating polymer matrix. Specifically, the ternary hybrid filler consists of boron nitride nanosheets (BNNSs), nitrogen-doped carbon nanotubes (N-CNTs), and silver nanowires (Ag NWs). The mass fraction of the ternary hybrid filler is 30%~50%, and the mass ratio of BNNSs, N-CNTs, and Ag NWs is (6~8):(1~2):(1~2). Figure 3 The typical microstructures of the two key nanofillers used in this embodiment are shown, among which... Figure 3 Figure (a) shows the SEM image of N-CNTs. Figure 3 Figure (b) shows a TEM image of N-CNTs. Figure 3 Figure (c) shows the SEM image of BNNSs. The aforementioned microstructure forms the structural basis for the high-performance thermal conductivity of the nano-thermal interlayer in this invention, as detailed below: (1) Morphological characteristics and thermal conductivity enhancement mechanism of N-CNTs Figure 3 Figure (a) in the middle Figure 3 (Figure (b) in the middle): Depend on Figure 3 As shown in Figure (a), N-CNTs exhibit a high aspect ratio fibrous or tubular structure, interwoven to form a network configuration; TEM image ( Figure 3 Figure (b) further shows the hollow tube wall and the defects or bamboo-like structure introduced by nitrogen doping. The contribution of this morphology to the thermal conductivity is mainly reflected in the following aspects: First, an in-plane heat conduction network is constructed. High aspect ratio N-CNTs are easy to overlap in the horizontal direction, forming continuous phonon transport channels, which significantly improves the in-plane thermal conductivity of the nano heat dissipation interlayer.

[0028] Second, it improves interfacial bonding and reduces interfacial thermal resistance. Unlike ordinary carbon nanotubes, nitrogen atoms in N-CNTs can form strong interfacial interactions with the polymer matrix and other fillers (such as BNNSs). This "anchoring" effect allows N-CNTs to achieve good interfacial wetting and bonding in composite materials without strong acid or alkali activation treatment, thereby significantly reducing the interfacial thermal resistance between the filler and the matrix. Interfacial thermal resistance is one of the key bottlenecks limiting the thermal conductivity of traditional carbon nanotube composites, and the nitrogen doping strategy of this invention effectively solves this problem.

[0029] Third, bridging effect. N-CNTs act like "nanowires" and can effectively bridge adjacent BNNSs (sheet-like) and Ag NWs, forming a continuous and dense three-dimensional thermally conductive network in the insulating polymer matrix.

[0030] Fourth, the contribution of high conductivity. N-CNTs themselves have good conductivity, which can work in synergy with Ag NWs to optimize the electrical performance of the circuit board and meet the power output and signal transmission requirements of the street light controller.

[0031] (2) Morphological characteristics and thermal conductivity enhancement mechanism of BNNSs Figure 3 (c) in the middle: Depend on Figure 3 As shown in Figure (c), BNNSs exhibit a lamellar structure with large lateral dimensions (micrometers) and a thickness of nanometers. The contribution of this morphology to thermal conductivity is mainly reflected in: First, high intrinsic thermal conductivity and phonon matching. Hexagonal boron nitride (h-BN) itself has extremely high in-plane thermal conductivity (theoretically up to about 600 W / m·K), and its phonon spectrum matches well with the polymer matrix, allowing heat to be conducted at high speed along the lattice of BNNSs.

[0032] Second, the heat island effect. Large, flat BNNSs sheets act as highly efficient "heat islands" in composite materials. When multiple BNNSs are connected by N-CNTs or Ag NWs, long-range heat conduction pathways can be formed across the entire sandwich.

[0033] Third, electrical insulation is guaranteed. BNNSs is an excellent electrical insulator, which enables the nano heat dissipation interlayer to maintain a high breakdown voltage (≥3kV) while having high thermal conductivity, thus meeting the electrical safety requirements of the circuit board.

[0034] (3) Synergistic effect of ternary hybrid packing: comprehensive Figure 3 Figures (a)-(c) illustrate how this invention employs a ternary hybrid filler system of BNNSs, N-CNTs, and Ag NWs to form a "sheet-wire-tube" structure. Specifically: BNNSs provide the "main channel" with high intrinsic thermal conductivity and electrical insulation; N-CNTs act as "connectors" and "interface optimizers," constructing a three-dimensional network and reducing interfacial thermal resistance; Ag NWs further enhance electrical conductivity and localized thermal conductivity pathways. The three fillers overlap and synergistically interact at the microscale, achieving a thermal conductivity enhancement effect far exceeding that of a single filler, while also considering electrical insulation, process compatibility, and mass production feasibility.

[0035] Figure 3 The microstructure shown demonstrates that the present invention can successfully prepare N-CNTs and BNNSs with ideal morphology. It is the specific "sheet-wire-tube" three-dimensional interpenetrating structure mentioned above that ensures that the nano heat dissipation interlayer achieves the key performance indicators of "in-plane thermal conductivity ≥18W / m·K and vertical thermal conductivity ≥6W / m·K", providing a structural basis for the reliable operation of street light controllers in outdoor high-temperature and enclosed environments.

[0036] The thermal conductivity of nano-heat dissipation films with different filler ratios is as follows: Figure 4 As shown.

[0037] The nano-heat dissipation interlayer 2 has an in-plane thermal conductivity ≥18W / m·K, a vertical thermal conductivity ≥6W / m·K, and a breakdown voltage ≥3kV. A conductive circuit layer 3 is disposed above the nano-heat dissipation interlayer 2. This conductive circuit layer 3 is etched to form the circuitry required for the street light controller, including a core control circuit, a PWM dimming circuit, a power output circuit, a wireless communication module circuit, and a power management circuit. The wireless communication module is selected from LoRa, NB-IoT, and 4G Cat.1 modules.

[0038] Several thermally conductive vias 4 are provided that penetrate the conductive circuit layer 3 and the nano heat dissipation interlayer 2 and extend to the base layer 1. The walls of the thermally conductive vias 4 are filled with nano thermally conductive gel to form a highly efficient thermally conductive channel in the vertical direction.

[0039] An embedded power device cavity 5 is disposed below the conductive circuit layer 3 and in direct contact with the nano heat dissipation interlayer 2. The embedded power device cavity 5 is used to accommodate the power chip 6 of the street light controller. The embedded power device cavity 5 is filled with nano thermally conductive gel 7, with a gel thermal conductivity ≥5W / m·K. The power chip 6 includes a power MOSFET, a DC-DC power module, a rectifier bridge, etc.

[0040] Thermally conductive protrusions 8 are provided on the edge of the circuit board. These protrusions 8 are designed to contact the inner wall of the metal housing 9 of the street light controller, forming a low thermal resistance heat conduction path between the circuit board and the housing. When the circuit board is installed inside the metal housing 9 of the street light controller, the contact surface between the thermally conductive protrusions 8 and the inner wall of the controller's metal housing 9 is coated with thermally conductive silicone grease or nano-thermal conductive gel to form a low thermal resistance heat conduction path. Simultaneously, heat dissipation fins 10 are provided on the exterior of the controller's metal housing 9.

[0041] The fabrication process of the above circuit board is as follows: Figure 2 As shown, the specific steps are as follows: S1. Preparation of special nano heat dissipation paste for street light controllers.

[0042] BNNSs (average flake diameter 1~5μm, thickness 10~50nm), N-CNTs (tube diameter 10~20nm, length 5~15μm), and AgNWs (diameter 30~50nm, length 8~20μm) were dispersed in an organic solvent containing polyvinylpyrrolidone at a mass ratio of (6~8):(1~2):(1~2), and ultrasonically dispersed for 2~3h to obtain a nanofiller mixture with a solid content of 25%~35%; then a high-temperature resistant epoxy resin matrix (glass transition temperature T) was added. g The mixture (≥150℃) and a latent curing agent are ground 3-5 times using a three-roll mill to obtain a special nano heat dissipation slurry for street light controllers, with a viscosity of 3000-6000 cP (25℃).

[0043] S2. Construct a nano heat dissipation interlayer.

[0044] Nano heat dissipation paste is coated on the substrate layer 1 by screen printing or slit coating, with the thickness controlled at 80~150μm; after vacuum degassing, a stepped temperature curing process is adopted: 80℃ / 1h→120℃ / 1h→160℃ / 2h to obtain a nano heat dissipation interlayer 2 with an anisotropic thermal conductive network structure.

[0045] S3. Fabricate the embedded power device cavity.

[0046] An embedded power device cavity 5 is formed in the nano heat dissipation interlayer 2 by laser ablation or mechanical milling, with a cavity depth of 60% to 90% of the thickness of the nano heat dissipation interlayer. Nano silver conductive adhesive is coated on the inner wall of the cavity, the power chip 6 is placed at the bottom of the cavity, and then nano thermal conductive gel 7 is filled. After the gel solidifies, a direct thermal interface is formed between the power chip 6 and the nano heat dissipation interlayer 2.

[0047] S4. Set conductive lines and thermal vias.

[0048] A conductive circuit layer 3 with a thickness of 35~70μm is formed on the surface of the nano heat dissipation interlayer 2 by using copper cladding or sputtering copper seed layer combined with electroplating to thicken it. The conductive circuit layer 3 contains the functional circuit required by the street light controller. Micro-vias with a diameter of 0.2~0.5mm are drilled using a CO2 laser, and after plasma cleaning, they are filled with nano thermal conductive gel 7. Electroplating is performed again to make the two ends of the vias conductive with the conductive circuit layer 3, forming a vertical thermal conductive via 4.

[0049] S5, Integrated edge heat conduction structure.

[0050] Thermally conductive bosses 8 are machined on the edge of the circuit board. Thermally conductive bosses 8 are coated with thermally conductive silicone grease or nano thermally conductive gel 7 to ensure that when the circuit board is installed in the metal housing 9 of the street light controller, the thermally conductive bosses 8 make contact with the inner wall of the housing, so as to realize direct heat conduction between the circuit board and the housing.

[0051] S6. Surface encapsulation and aging test.

[0052] Thermally conductive solder resist ink is coated on the surface of the circuit board. After heat curing, the finished circuit board is subjected to functional testing and high-temperature aging testing (70℃ / 48h) to ensure the reliability of the street light controller in outdoor high-temperature environment.

[0053] The aforementioned circuit board is used to further complete the integrated smart street light node controller. The edge heat conduction structure is designed as follows: the height of the heat conduction boss 8 is interference-fitted with the inner wall of the controller metal housing 9 (interference amount 0.1~0.2mm), and the contact surface is coated with thermal grease (thermal conductivity 3W / m·K). The outer wall of the controller metal housing 9 is provided with housing heat dissipation fins 10.

[0054] This embodiment further provides two circuit board samples: one is an LED smart street light controller circuit board, and the other is a high-pressure sodium lamp smart controller circuit board. The thermal conductivity of the nano-heat dissipation film used is as follows: Figure 4 The last three groups of bar charts are shown.

[0055] In the LED smart street light controller circuit board, a 1.6mm thick high thermal conductivity aluminum substrate (thermal conductivity 2.5W / m·K) is selected as the base layer 1. BNNSs, N-CNTs, and Ag NWs are weighed at a mass ratio of 7:1.5:1.5, ultrasonically dispersed, and then composited with high-temperature resistant epoxy resin. This is then screen-printed into a 120μm nano-heat dissipation interlayer 2 (measured in-plane thermal conductivity 21W / m·K, vertical thermal conductivity 7.2W / m·K, breakdown voltage 3.5kV). The cavity depth of the embedded power device cavity 5 is 100μm, laser-processed, and the MOSFET power transistor (model IRBB4110) and DC-DCP module of the LED street light controller are placed inside, filled with nano-thermal conductive gel (thermal conductivity 6W / m·K). A conductive circuit layer 3 is formed using an electroplating copper process. This conductive circuit layer 3 contains the STM32 core control circuit, PWM dimming circuit, and LORA wireless communication module circuit. A 0.3mm via was drilled and filled with nano-thermal conductive gel 7. Thermally conductive bumps 8 were machined along the edge of the circuit board. The circuit board was then mounted in the metal housing 9 of the street light controller and subjected to a full-load test at an ambient temperature of 60℃. The measured MOSFET case temperature was 92℃ (112℃ for traditional aluminum substrate solutions). The temperature profile is shown below. Figure 5 As shown, the operating temperature requirements of the street light controller are met.

[0056] In the circuit board of the high-pressure sodium lamp intelligent controller, a thermally modified FR-4 substrate (thermal conductivity 1.5 W / m·K) is used as the base layer 1. A 100 μm thick nano-heat dissipation interlayer 2 is constructed with a filler ratio of 6:2:2 (BNNSs:N-CNTs:Ag NWs), and is screen-printed followed by step curing. The conductive circuit layer 3 contains the high-pressure sodium lamp voltage regulation control circuit, AC sampling module, and LORA wireless transceiver module. Vias are filled using a laser + ultrasonic filling process with nano-thermal conductive gel 7. The circuit board is used in the high-pressure sodium lamp intelligent controller (input voltage AC220V, load power 250W). After 72 hours of continuous operation at an ambient temperature of 40℃, the core microcontroller temperature reached 78℃ (compared to 115℃ for the traditional FR-4 solution). The temperature profile is shown below. Figure 6 As shown, the inductive ballast and high-pressure sodium lamp load module operated stably without thermal protection or malfunction. At an ambient temperature of 50℃, the temperature of the control board in a traditional FR-4 combined with a fan solution was 105℃, while the temperature of this circuit board was 77℃, a decrease of 28℃. The temperature curve is shown below. Figure 7 As shown, it eliminates the need for active cooling by a fan, thus eliminating the potential for fan failure in outdoor environments.

[0057] Therefore, this invention employs the aforementioned street light controller circuit board based on nano-heat dissipation materials and its fabrication method. Through a systematic thermal design that integrates the internal nano-heat dissipation layer and the casing, a multi-dimensional and efficient heat conduction path is constructed to reduce the operating temperature of core power devices, thus solving the heat dissipation problem of street light controllers in high-temperature, enclosed outdoor environments. The fanless passive heat dissipation solution avoids the potential failure of active heat dissipation components outdoors, improving equipment reliability. Simultaneously, the circuit board is compatible with multiple functional modules, adapting to various street light controller application scenarios, effectively reducing thermal management costs, slowing down component aging, and meeting the long-life operation requirements of street light controllers.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A controller circuit board for streetlights based on nano-heat dissipation materials, characterized in that, The circuit board includes a base layer (1), a nano heat dissipation interlayer (2) is disposed above the base layer (1), and a conductive circuit layer (3) is disposed above the nano heat dissipation interlayer (2); a plurality of thermally conductive vias (4) are disposed penetrating the conductive circuit layer (3) and the nano heat dissipation interlayer (2) and extending to the base layer (1); an embedded power device cavity (5) is disposed below the conductive circuit layer (3) and in direct contact with the nano heat dissipation interlayer (2); a thermally conductive boss (8) is disposed on the edge of the circuit board, and the thermally conductive boss (8) is used to contact the inner wall of the metal housing (9) of the street light controller. The nano heat dissipation interlayer (2) comprises a ternary hybrid filler and an insulating polymer matrix; the ternary hybrid filler specifically comprises boron nitride nanosheets (BNNSs), nitrogen-doped carbon nanotubes (N-CNTs), and silver nanowires (Ag NWs). The mass fraction of the ternary hybrid filler is 30%~50%, and the mass ratio of BNNSs, N-CNTs to Ag NWs is (6~8):(1~2):(1~2).

2. The street light controller circuit board based on nano-heat dissipation materials according to claim 1, characterized in that, The conductive line layer (3) includes the core control circuit, pulse width modulation (PWM) dimming circuit, power output circuit, wireless communication module circuit and power management circuit required by the street light controller. The wireless communication module is selected from the long-range LORA module, narrowband Internet of Things (NB-IoT) module and 4G Cat.1 module.

3. The street light controller circuit board based on nano-heat dissipation material according to claim 1, characterized in that, The in-plane thermal conductivity of the nano heat dissipation interlayer (2) is ≥18W / m·K, the vertical thermal conductivity is ≥6W / m·K, and the breakdown voltage is ≥3kV.

4. The street light controller circuit board based on nano-heat dissipation material according to claim 1, characterized in that, The embedded power device cavity (5) is filled with nano thermally conductive gel (7), the gel thermal conductivity is ≥5W / m·K, and the embedded power device cavity (5) is used to accommodate the power chip (6) of the street light controller; the power chip (6) includes a power metal-oxide-semiconductor field-effect transistor (MOSFET), a rectifier bridge and a DC-DC power supply module.

5. The street light controller circuit board based on nano-heat dissipation material according to claim 1, characterized in that, When the circuit board is installed inside the metal housing (9) of the street light controller, the contact surface between the thermally conductive boss (8) and the inner wall of the controller metal housing (9) is coated with thermally conductive silicone grease or nano-thermal conductive gel to form a low thermal resistance thermal conduction path.

6. A method for fabricating a controller circuit board for streetlights based on nano-heat dissipation materials, characterized in that, Includes the following steps: S1. Disperse BNNSs, N-CNTs and Ag NWs in an organic solvent containing polyvinylpyrrolidone at a mass ratio of (6~8):(1~2):(1~2), and ultrasonically disperse for 2~3 hours to obtain a nanofiller mixture with a solid content of 25%~35%; then add a high-temperature resistant epoxy resin matrix and a latent curing agent, and grind it 3~5 times with a three-roll mill to obtain a special nano heat dissipation slurry for street light controllers with a viscosity of 3000~6000 cP (25℃); S2. The nano heat dissipation paste is coated on the substrate layer (1) by screen printing or slit coating, and the thickness is controlled to be 80~150μm. After vacuum degassing, a stepped temperature curing process is adopted: 80℃ / 1h→120℃ / 1h→160℃ / 2h to obtain a nano heat dissipation interlayer (2) with an anisotropic thermal conductive network structure. S3. An embedded power device cavity (5) is formed in the nano heat dissipation interlayer (2) by laser ablation or mechanical milling. The cavity depth is 60%~90% of the thickness of the nano heat dissipation interlayer (2). Nano silver conductive adhesive is coated on the inner wall of the cavity, the power chip (6) is placed at the bottom of the cavity, and then nano thermal conductive gel (7) is filled. S4. A conductive circuit layer (3) with a thickness of 35~70μm is formed on the surface of the nano heat dissipation interlayer (2) by using copper cladding or sputtering copper seed layer combined with electroplating to thicken the layer. The conductive circuit layer (3) contains the functional circuits required by the street light controller. CO2 laser drilling is used to drill out the conductive circuit layer (3). Ф Micro-vias of 0.2~0.5mm are filled with nano-thermal conductive gel (7) after plasma cleaning; electroplating is performed again to make the two ends of the micro-vias connected to the conductive circuit layer (3) to form vertical thermal conductive vias (4); S5. Process thermally conductive bosses (8) on the edge of the circuit board. Coat the surface of the thermally conductive bosses (8) with thermally conductive silicone grease or nano thermally conductive gel (7) to ensure that when the circuit board is installed in the metal housing (9) of the street light controller, the thermally conductive bosses (8) form contact with the inner wall of the housing, so as to realize direct heat conduction between the circuit board and the housing. S6. Coat the surface of the circuit board with thermally conductive solder resist ink, and perform functional testing and high-temperature aging testing on the finished circuit board after heat curing.

7. A street light controller, characterized in that: The controller circuit board for streetlights based on nano heat dissipation materials as described in any one of claims 1-5, and a streetlight controller metal housing (9) housing the circuit board, wherein heat dissipation fins (10) are provided on the outside of the controller metal housing (9), and the heat-conducting bosses (8) on the edge of the circuit board are in interference fit contact with the inner wall of the controller metal housing (9) to form a heat conduction path, and the contact surface is coated with thermal grease or nano thermal gel (7).

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