A method for manufacturing a modular inductor

Abstract

The application discloses a kind of manufacturing methods of module inductance, comprising the following steps: S1, inductance selection and stripping paint;S2, micro-nano texture processing;S3, electroplating and AOI detection;S4, tin paste printing and device mounting;S5, gradient heat conduction coating preparation;S6, reflow soldering and heat dissipation mounting;S7, detection and packaging.The application forms the microstructure of circular groove and semicircular convex on the surface of inductance substrate by micro-nano texture processing, increases the contact area of electroplated layer and substrate, improves the bonding strength of plating layer and substrate, avoids the peeling of plating layer in long-term use, guarantees the stability of the conductive performance of module inductance, can disperse the stress generated by thermal cycle and mechanical vibration, reduces the probability of inductance substrate cracking and deformation, and improves the structural stability of inductance itself.

Description

Technical Field

[0001] This invention relates to the field of inductor technology, and more particularly to a method for manufacturing a modular inductor. Background Technology

[0002] Inductors are fundamental electronic components that store magnetic field energy in circuits. They are widely used in electronic equipment circuits for filtering, oscillation, power conversion, and other functions, working in conjunction with devices such as MOSFETs, ICs, and capacitors to achieve circuit functions.

[0003] In the existing technology, devices such as MOSFETs, ICs, capacitors, and inductors are all independently packaged. After production and processing, they are fixed to the preset pad positions on the PCBA board through a soldering process. The devices are electrically connected through copper foil lines on the PCBA board to realize signal transmission and energy conduction.

[0004] However, MOSFETs, inductors, ICs, capacitors, and other components are prone to heat generation. If the temperature gets out of control, the device temperature can soar to hundreds of degrees Celsius within seconds without intervention, directly causing the silicon wafer to melt and the package to crack. Normal temperature increases also lead to a decrease in lifespan: for every 10°C increase, the lifespan is halved. High temperatures and repeated temperature changes generate huge mechanical stress, eventually leading to damage to the physical structure of the device.

[0005] Accordingly, this application proposes a method for manufacturing a modular inductor. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for manufacturing modular inductors.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for manufacturing a modular inductor includes the following steps:

[0009] S1. Inductor selection and stripping

[0010] Inductors include, but are not limited to, rectangular inductors. They can be purchased from the market or developed in-house. The size is selected according to actual needs. The solderable surface of the inductor is defined as the soldering surface, the surface parallel to the soldering surface is the bottom surface, the surface perpendicular to the soldering surface with a large area is the long side surface, and the surface perpendicular to the soldering surface with a small area is the short side surface. The inductor is placed in a customized laser stripping machine to strip the soldering surface, the short side surface, and the bottom surface, ensuring effective connection of each stripped area. The actual stripping size and the reserved area for device installation are determined according to design requirements. Only the insulating varnish layer in the designated area is removed, exposing the conductive substrate.

[0011] S2, Micro-nano texturing

[0012] Micro-nano texturing is performed on the surface of the inductive and conductive substrate after the paint is stripped in step S1. Plasma etching is used to process uniformly distributed circular grooves on the substrate surface. The irregular rough surface is conducive to the adhesion of the electroplating layer and the thermal conductive layer. A semi-circular protrusion is processed at the center of each circular groove. The surface of the protrusion and the inner wall of the groove are treated with a rounded transition to control the distribution spacing and size consistency of each structure. After processing, the substrate structure is kept intact, providing adhesion conditions for the subsequent electroplating layer and thermal conductive coating.

[0013] S3, Electroplating and AOI Inspection

[0014] After the S2 step, the inductor stripping area is subjected to multi-layer electroplating, with the outermost layer being tin-plated. After the electroplating is completed, AOI inspection equipment is used to check the flatness and parallelism of the plating layer to ensure that there are no obvious pits or protrusions. At the same time, the integrity of the stripping, the uniformity of electroplating, and the overall appearance of the inductor are also checked.

[0015] S4, Solder paste printing and component mounting

[0016] A special inductor solder paste printing fixture is made to fix and limit the bottom and short sides of the inductor; a special stencil is made to print solder paste on the fixing surface. After the solder paste is printed, the height, volume and area of ​​the solder paste are detected by SPI to ensure that it meets the process requirements. MOSFETs, ICs and other devices are mounted on the solder paste printing area according to the preset layout. If there are design requirements for the electrode surface, the capacitors are manually soldered after the subsequent soldering is completed.

[0017] S5, Preparation of gradient thermal conductive coating

[0018] A gradient thermally conductive coating was prepared in situ on the surface of the inductor after mounting in step S4 using a plasma spraying process. The coating consists of a base layer, an intermediate layer, and a surface layer.

[0019] The bottom layer is a nickel-chromium bonding layer, accounting for 6%-8% of the total coating thickness, with 5 vol% spherical copper powder particles added;

[0020] The intermediate layer is an aluminum nitride-silicon carbide composite layer, accounting for 70%-75% of the total coating thickness, with 12 vol% spherical aluminum nitride particles and 8 vol% flake silicon carbide particles added.

[0021] The surface layer is a nano-beryllium oxide modified layer, accounting for 18%-22% of the total coating thickness, with 4 vol% dumbbell-shaped nano-beryllium oxide particles added;

[0022] During coating preparation, the surface structure of the inductor is matched, the grooves are filled and the protrusions are wrapped; if the S2 step is not performed, the coating is uniformly covered on the flat substrate surface.

[0023] After micro-nano etching, the inductor surface has a set roughness. The electroplating layer thickness is 0.3mm, which is compatible with the surface roughness and meets the preset range. The surface grooves and protrusions formed by electroplating can be fully filled and wrapped by the gradient thermally conductive coating, which improves the coating bonding strength while ensuring the coating adhesion stability.

[0024] S6, Reflow Soldering and Thermal Mounting

[0025] The inductor assembly with the mounted components is sent into the reflow soldering equipment, where the solder paste is melted and solidified through temperature cycling, thus achieving electrical connection between the components and the inductor.

[0026] After soldering, attach a suitable heat dissipation device, including but not limited to a copper heat sink, to one side of the inductor. Use PI double-sided tape with a thermally conductive adhesive layer or directly apply a nano-oxidation wrinkle-modified coating to the entire inductor for insulation. Apply the coating evenly to the long side, connecting the soldered side with the thermally conductive coating, the short side, and the bottom. Select a copper sheet with a thickness of 0.2-1mm and an appropriate area. The copper sheet should not be directly connected to the other four sides. The heat from the other four sides and the inductor body is transferred to the copper sheet by the PI double-sided tape with a thermally conductive adhesive layer, and then the copper sheet dissipates heat to the environment. This ensures that the heat dissipation device is tightly attached to the inductor or the gradient thermally conductive coating, forming a complete heat conduction path to transfer the heat generated by the inductor and the device.

[0027] S7. Testing and Packaging

[0028] Customized testing equipment is used to conduct electrical performance and appearance inspections on the modules to verify that the electrical performance meets the standards and that there are no defects in the appearance. After passing the inspection, the modules are taped and packaged, boxed, and labeled with product model, specifications, and production date to complete the finished product preparation.

[0029] Preferably, in step S1, the customized laser paint stripping machine adjusts the paint stripping parameters according to the selected inductor size. The area size and connection status are monitored in real time during the paint stripping process to ensure that there is no missed or over-stripping, and the conductive substrate is uniformly exposed, providing good surface conditions for the electroplating process. The rectangular inductor selection must meet the requirements of welding, electroplating and heat dissipation device mounting processes. After purchase, the inductor is pre-treated to remove surface dust and impurities without damaging the insulating varnish layer.

[0030] Preferably, in step S2, the vacuum level in the reaction chamber is controlled during the plasma etching process, and the etching rate is adjusted by adjusting the plasma density. The processed circular groove and semi-circular protrusion have the same size, and there are no sharp corners or burrs at the arc transition. After processing, debris and impurities are removed by cleaning to ensure the cleanliness of the substrate surface, increase the contact area between the electroplated layer and the substrate, and help improve the heat dissipation effect.

[0031] Preferably, in step S3, multi-layer electroplating is carried out according to a preset plating order and thickness, with the outermost layer being tin-plated to ensure soldering compatibility. The AOI inspection equipment accurately identifies defects through image acquisition and analysis technology, generates inspection result files, and unqualified products are transferred to the rework process to avoid affecting the module integration effect and performance.

[0032] Preferably, in step S4, the positioning accuracy of the dedicated fixing fixture is adapted to the inductor size, and it is made of wear-resistant material so as not to damage the inductor surface during fixing; the mesh size and distribution of the dedicated stencil correspond to the soldering points, the stencil thickness matches the solder paste printing thickness, and the printing parameters are adjusted when the SPI test result exceeds the preset range. The device is mounted using a high-precision pick-and-place machine to ensure that the pins are accurately aligned with the solder paste coating area.

[0033] Preferably, in step S5, the addition of particles to each layer of the coating is carried out by a combination of mechanical stirring and ultrasonic dispersion to ensure that the particles are evenly distributed and do not agglomerate. During the preparation process, the coating thickness is monitored in real time, and the spraying parameters are adjusted to control the thickness of each layer. When filling the groove, it is ensured that the inner wall and the raised surface are completely covered, with no gaps or bubbles, thereby reducing the resistance to heat transfer.

[0034] Preferably, in step S6, the reflow soldering process controls the heating, holding, and cooling stages according to a preset temperature curve. When manually soldering capacitors, an adapter tool is used to control the soldering temperature and time to avoid damaging the device and inductor substrate. Before mounting the heat dissipation device, the surface of the inductor or coating is cleaned, and uniform pressure is applied to ensure full contact without any local suspension. The mounting position is fixed on one side of the inductor to ensure a smooth heat conduction path.

[0035] Preferably, in step S7, the electrical performance testing of the customized testing equipment includes items such as conduction resistance, insulation resistance, and withstand voltage; the appearance inspection includes items such as structural integrity, accuracy of device installation position, and no surface damage; the tape and reel packaging ensures that the module is not damaged during transportation; and the label information facilitates product traceability and management.

[0036] The present invention has the following beneficial effects:

[0037] 1. By using inductors as the conduction carrier, MOSFETs, ICs, capacitors, and other components are directly soldered onto the inductor, replacing the traditional method of soldering components independently to the PCBA board. This reduces the conduction lines connecting the inductor and capacitor, lowering energy consumption while saving PCBA board space and improving space utilization. The components share the heat dissipation device mounted on the inductor, resulting in more direct and stable heat dissipation compared to traditional PCB board heat dissipation methods. Furthermore, the integrated design shortens the signal transmission path, improves high-frequency performance and signal integrity, enhances system performance, increases reliability, and reduces production costs.

[0038] Second, through micro-nano texturing, a microstructure of circular grooves and semi-circular protrusions is formed on the surface of the inductor substrate. This increases the contact area between the electroplated layer and the substrate, enhances the bonding strength between the plating layer and the substrate, prevents the plating layer from peeling off during long-term use, ensures the stability of the inductor's conductivity, disperses the stress generated by thermal cycling and mechanical vibration, reduces the probability of cracking and deformation of the inductor substrate, and improves the structural stability of the inductor itself.

[0039] Third, by preparing a gradient thermally conductive coating, layering design, and adding particles of different shapes, an efficient and continuous heat transfer channel is constructed, which improves the heat transfer efficiency of the inductor surface, enabling the heat generated by the inductor and electronic devices to be quickly conducted to the heat dissipation device, enhancing the heat dissipation effect and accelerating the heat conduction rate to the heat dissipation device, meeting the heat dissipation requirements of PCBA boards. In addition, the coating can form a protective layer on the inductor surface, isolating it from corrosive media and wear in the external environment, and extending the service life of the inductor.

[0040] Fourth, by combining micro-nano texture processing with gradient thermal conductive coating preparation, the microstructure provides a three-dimensional adhesion space for the gradient thermal conductive coating, enabling the coating to form a mechanical locking effect with the substrate, which greatly improves the coating's anti-peeling ability and avoids peeling and detachment of the coating during long-term use. The two work together to guide heat convergence through the microstructure, and with the differentiated thermal conductivity of the particles in the coating, a shielding effect is formed on the electromagnetic radiation generated by high-frequency signals, optimizing the electromagnetic environment of the module and improving the stability of signal transmission. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the basic process for manufacturing a modular inductor proposed in this invention;

[0042] Figure 2 This is a cross-sectional view of the structure after micro-nano texture processing in the manufacturing method of the modular inductor proposed in this invention.

[0043] Figure 3 This is a diagram illustrating the layers of a gradient thermally conductive coating used in the manufacturing method of a module inductor proposed in this invention.

[0044] Figure 4 This is a diagram showing the paint stripping process on the solder surface of a method for manufacturing a modular inductor according to the present invention. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0046] Example 1:

[0047] S1. Inductor selection and stripping

[0048] Rectangular inductors are used, sourced commercially, with basic dimensions of 5mm, 6mm, and 8mm (L*W*H). Other sizes of the same type can be selected. The solderable surface of the inductor is defined as the solder surface, the surface parallel to the solder surface is the bottom surface, the surface perpendicular to the solder surface with a larger area is the long side surface, and the surface perpendicular to the solder surface with a smaller area is the short side surface.

[0049] After purchase, the inductor surface is wiped with anhydrous ethanol to remove dust and oil without damaging the insulating varnish layer. The pre-treated inductor is then placed in a custom laser stripping machine. The laser wavelength is set to 1064nm and the stripping speed to 50mm / s. The solder surface, short side, and bottom surface are stripped. The stripping area for each surface is defined according to the design requirements. The overlap width between adjacent stripping areas is ≥0.3mm. Only the insulating varnish layer in the designated area is removed, so that the conductive substrate is evenly exposed without any missed or over-stripped areas.

[0050] S3, Electroplating and AOI Inspection

[0051] After paint stripping, the conductive areas of the inductor undergo multi-layer electroplating, depositing copper, nickel, and tin layers in that order. The electroplating current density is 2A / dm², and the total electroplating time is 30 minutes. The outermost tin layer ensures solderability. After electroplating, AOI (Automated Optical Inspection) equipment is used to check the plating flatness (≤0.01mm) and parallelism (≤0.02mm), ensuring there are no obvious pits or protrusions. Simultaneously, the integrity of the paint stripping, the uniformity of the electroplating layer, and the overall appearance of the inductor are inspected. Defects are automatically identified, and unqualified products are transferred to the rework process, while qualified semi-finished products are selected.

[0052] S4, Solder paste printing and component mounting

[0053] A special solder paste printing fixture is manufactured with a positioning accuracy of ±0.01mm. Made of wear-resistant material, it provides fixed and limited positioning for the bottom and short sides of the inductor with a fixing pressure of 0.1MPa. A special steel mesh with a thickness of 0.12mm is manufactured simultaneously, with the mesh size and distribution precisely corresponding to the welding points.

[0054] SAC305 solder paste was printed onto the inductor mounting surface using a fixture and stencil. After printing, the height, volume, and area of ​​the solder paste were checked using SPI testing equipment, and the printing parameters were adjusted if they were not up to standard. A high-precision pick-and-place machine was used to mount MOSFETs, ICs, and other devices onto the solder paste area to ensure accurate pin alignment. If there were design requirements for the electrode surface, the devices were manually soldered onto the electrode surface using a 60W soldering iron at 350℃ for 3 seconds after subsequent soldering.

[0055] S6, Reflow Soldering and Thermal Mounting

[0056] The inductor assembly with the mounted components is fed into the reflow soldering equipment and soldered according to the preset temperature profile: a heating rate of 3℃ / s from room temperature to 150℃, a holding time of 60s at 150℃, a heating rate of 2℃ / s from 150℃ to 230℃, a holding time of 20s at 230℃, and then allowed to cool naturally to melt and solidify the solder paste to achieve electrical connection. After soldering, the inductor surface is wiped with a lint-free cloth to remove residual flux.

[0057] Select a suitable copper heat sink. Use PI double-sided tape with a thermally conductive adhesive layer or directly apply a nano-oxidation wrinkle-modified coating seamlessly to the entire inductor for insulation. Apply the coating evenly to the long side, the soldering surface connected to the thermally conductive coating, the short side, and the bottom. Select a copper sheet with a thickness of 0.2-1mm and a suitable area. The copper sheet should not be directly connected to the other four sides. The heat from the other four sides and the inductor body is transferred to the copper sheet through the PI double-sided tape with a thermally conductive adhesive layer, and then the copper sheet dissipates heat to the environment. This ensures that the heat sink is in close contact with the inductor or the gradient thermally conductive coating, forming a complete heat conduction path to transfer the heat generated by the inductor and the device. It is important to note that when mounting on one side of the inductor, apply a uniform pressure of 0.2MPa to ensure that the heat sink is in full contact with the inductor without any local suspension, thus forming a heat conduction path.

[0058] S7. Testing and Packaging

[0059] Customized testing equipment is used to test the modules. Electrical performance testing includes continuity resistance ≤50mΩ, insulation resistance ≥1000MΩ, and withstand voltage ≥2kV. Visual inspection is performed using a combination of manual inspection and machine vision to verify the module's structural integrity, component installation position deviation ≤0.05mm, and surface undamagedness. After passing inspection, the modules are taped, packaged, and labeled with the product model, specifications, and production date, completing the finished product manufacturing process.

[0060] Example 2:

[0061] S1. Inductor selection and stripping

[0062] Same as Example 1.

[0063] S2, Micro-nano texturing

[0064] Micro-nano texturing was performed on the surface of the inductive and conductive substrate after paint stripping using plasma etching. Before etching, the substrate was fixed in a tooling fixture inside the etching cavity to ensure that the substrate levelness was ≤0.005mm.

[0065] During the etching process, uniformly distributed circular grooves are processed on the surface of the substrate. The grooves are 12μm in diameter and 10μm in depth, with a center-to-center distance of 22μm between adjacent grooves and a sidewall perpendicularity of ≥89°. An integrated semi-circular protrusion is processed at the center of each circular groove. The surface of the protrusion and the inner wall of the groove are transitioned by a 1μm radius arc, without sharp corners or burrs.

[0066] During the processing, the structural dimensions are monitored in real time through an online detection system to ensure that the dimensional deviation is ≤ ±0.5μm. After processing, a 0.5MPa high-pressure nitrogen gun is used to blow away the surface of the substrate to thoroughly remove metal debris and impurities generated by etching, ensuring the cleanliness of the substrate surface and maintaining the integrity of the overall structure of the substrate without cracks or deformation.

[0067] S3, Electroplating and AOI Inspection

[0068] Same as Example 1.

[0069] S4, Solder paste printing and component mounting

[0070] Same as Example 1.

[0071] S6, Reflow Soldering and Thermal Mounting

[0072] Same as Example 1.

[0073] S7. Testing and Packaging

[0074] Same as in Example 1,

[0075] Example 3:

[0076] S1. Inductor selection and stripping

[0077] Same as Example 1.

[0078] S3, Electroplating and AOI Inspection

[0079] Same as Example 1.

[0080] S4, Solder paste printing and component mounting

[0081] A special inductor solder paste printing and fixing fixture is manufactured with a positioning accuracy of ±0.01mm. It is made of SKD11 wear-resistant material and is used to fix and limit the bottom and short sides of the inductor with a fixing pressure of 0.1MPa. A special steel mesh is also manufactured with a thickness of 0.12mm and a mesh size of 0.3mm*0.5mm. The mesh distribution is precisely aligned with the soldering points on the inductor fixing surface.

[0082] SAC305 solder paste was printed onto the inductor mounting surface using a fixture and stencil. After printing, the height, volume, and area of ​​the solder paste were verified using SPI testing equipment. If the parameters were not up to standard, the printing parameters were adjusted and the printing was repeated. A high-precision pick-and-place machine with a placement accuracy of ±0.02mm was used to mount MOSFETs, ICs, and other devices onto the solder paste printing area, ensuring precise alignment between the device pins and the solder paste coating area. If there were design requirements for the electrode surface, after subsequent soldering processes, a 60W constant-temperature soldering iron was used to manually solder 0603 packaged capacitors onto the electrode surface, controlling the soldering temperature at 350℃ and the soldering time at 3 seconds, to avoid damaging the soldered devices and the inductor substrate.

[0083] S5, Preparation of gradient thermal conductive coating

[0084] A gradient thermally conductive coating is prepared in situ on the surface of the inductor after mounting using plasma spraying. Before spraying, the inductor component is fixed to the spraying fixture, and the non-spraying area is shielded with high-temperature tape. The temperature inside the spraying chamber is preheated to 80°C and the vacuum degree is controlled at 10Pa.

[0085] The total coating thickness is designed to be 0.3mm. It is sprayed in layers: base layer, intermediate layer, and top layer. The spraying parameters of each layer are independently adjustable. The functional particles of each layer are treated by mechanical stirring to ensure that the particles are evenly distributed in the coating slurry without agglomeration or sedimentation.

[0086] The bottom layer is a nickel-chromium bonding layer, accounting for 7% of the total coating thickness. The sprayed powder is NiCr80 / 20 alloy powder with a particle size of 50-100μm, with 5 vol% spherical copper powder particles added. The spraying current is 600A, the voltage is 40V, the powder feeding rate is 15g / min, and the spraying distance is 100mm. The bottom layer and the inductor substrate achieve metallurgical bonding with a bonding strength ≥30MPa.

[0087] Intermediate layer: Aluminum nitride-silicon carbide composite layer, accounting for 72% of the total coating thickness, serving as the main thermally conductive layer. The sprayed powder is a mixture of aluminum nitride powder and silicon carbide powder at a mass ratio of 7:3, with the addition of 12 vol% spherical aluminum nitride particles and 8 vol% flake silicon carbide particles. The spraying current is 700A, the voltage is 45V, the powder feeding rate is 20g / min, and the spraying distance is 90mm, ensuring a coating density of ≥95%.

[0088] Surface layer: Nano-beryllium oxide modified layer, with a thickness accounting for 21% of the total coating thickness. The sprayed powder is alumina powder with 4 vol% dumbbell-shaped nano-beryllium oxide particles added. The spraying current is 500A, the voltage is 35V, the powder feeding rate is 10g / min, the spraying distance is 110mm, and the surface roughness Ra is ≤1.6μm.

[0089] After each layer of spraying is completed, a 10-minute heat preservation treatment is performed to ensure tight bonding between layers and no delamination or cracking. After the overall coating is prepared, it is dried in a hot air drying oven at 120℃ for 30 minutes to remove residual solvents in the coating. Finally, the coating is evenly covered on the surface of the inductive flat substrate, without gaps, bubbles, or pinholes, thus creating a continuous and efficient heat transfer channel.

[0090] S6, Reflow Soldering and Thermal Mounting

[0091] Same as Example 1.

[0092] S7. Testing and Packaging

[0093] Customized testing equipment is used to conduct comprehensive testing on the modules. Electrical performance testing ensures that the conduction resistance is ≤50mΩ, insulation resistance is ≥1000MΩ, and withstand voltage is ≥2kV. Visual inspection combines manual inspection with machine vision to verify the integrity of the module structure and the component installation position deviation is ≤0.05mm. Specifically, the gradient thermal conductive coating is confirmed to be free of defects such as peeling, flaking, cracking, and pinholes, with a coating thickness deviation of ≤±0.02mm. After all tests are passed, the modules are taped, packaged, and boxed, with traceability labels containing the product model, specifications, production date, and production batch affixed, completing the finished product preparation.

[0094] Example 4

[0095] S1. Inductor selection and stripping

[0096] Same as Example 1.

[0097] S2, Micro-nano texturing

[0098] Micro-nano texturing was performed on the surface of the inductive and conductive substrate after paint stripping using plasma etching. Before etching, the substrate was fixed in a tooling fixture inside the etching cavity to ensure that the substrate levelness was ≤0.005mm.

[0099] During the etching process, the vacuum level in the reaction chamber is precisely controlled at 5Pa, the radio frequency power is adjusted to 300W to stabilize the plasma density, and the etching rate is controlled at 2μm / min. Uniformly distributed circular grooves are processed on the substrate surface, with a groove diameter of 12μm, a depth of 10μm, a center-to-center distance of 22μm between adjacent grooves, and a groove sidewall verticality of ≥89°.

[0100] Each circular groove has an integrated semi-circular protrusion machined at its center. The protrusion has a diameter of 5μm and a height of 4μm. The surface of the protrusion is transitioned to the inner wall of the groove with a radius of 1μm, without sharp corners or burrs. During the machining process, the structural dimensions are monitored in real time by an online detection system to ensure that the dimensional deviation is ≤±0.5μm. After machining, the substrate surface is purged with a 0.5MPa high-pressure nitrogen gun to thoroughly remove metal debris and impurities generated during etching, ensuring the cleanliness of the substrate surface and maintaining the integrity of the overall substrate structure without cracks or deformation.

[0101] S3, Electroplating and AOI Inspection

[0102] Same as Example 2.

[0103] S4, Solder paste printing and component mounting

[0104] Same as Example 1.

[0105] S4, Solder paste printing and component mounting

[0106] Same as Example 1.

[0107] S5, Preparation of gradient thermal conductive coating

[0108] A gradient thermally conductive coating is prepared in situ on the surface of the inductor after mounting using plasma spraying. Before spraying, the inductor component is fixed to the spraying fixture, and the non-spraying area is shielded with high-temperature tape. The temperature inside the spraying chamber is preheated to 80°C and the vacuum degree is controlled at 10Pa.

[0109] The total coating thickness is designed to be 0.3mm. It is sprayed in layers: base layer, intermediate layer, and top layer. The spraying parameters of each layer are independently adjustable. The functional particles of each layer are treated by mechanical stirring to ensure that the particles are evenly distributed in the coating slurry without agglomeration or sedimentation.

[0110] The bottom layer is a nickel-chromium bonding layer, accounting for 7% of the total coating thickness. The sprayed powder is NiCr80 / 20 alloy powder with a particle size of 50-100μm, with 5 vol% spherical copper powder particles added. The spraying current is 600A, the voltage is 40V, the powder feeding rate is 15g / min, and the spraying distance is 100mm. The bottom layer and the inductor substrate achieve metallurgical bonding with a bonding strength ≥30MPa.

[0111] Intermediate layer: Aluminum nitride-silicon carbide composite layer, accounting for 72% of the total coating thickness, serving as the main thermally conductive layer. The sprayed powder is a mixture of aluminum nitride powder and silicon carbide powder at a mass ratio of 7:3, with the addition of 12 vol% spherical aluminum nitride particles and 8 vol% flake silicon carbide particles. The spraying current is 700A, the voltage is 45V, the powder feeding rate is 20g / min, and the spraying distance is 90mm, ensuring a coating density of ≥95%.

[0112] Surface layer: Nano-beryllium oxide modified layer, with a thickness accounting for 21% of the total coating thickness. The sprayed powder is alumina powder with 4 vol% dumbbell-shaped nano-beryllium oxide particles added. The spraying current is 500A, the voltage is 35V, the powder feeding rate is 10g / min, the spraying distance is 110mm, and the surface roughness Ra is ≤1.6μm.

[0113] After each layer of spraying is completed, a 10-minute heat preservation treatment is performed to ensure tight bonding between layers and no delamination or cracking. After the overall coating is prepared, it is dried in a hot air drying oven at 120℃ for 30 minutes to remove residual solvents in the coating. Finally, the coating is evenly covered on the surface of the inductive flat substrate, without gaps, bubbles, or pinholes, thus creating a continuous and efficient heat transfer channel.

[0114] S6, Reflow Soldering and Thermal Mounting

[0115] Same as Example 1.

[0116] S7. Testing and Packaging

[0117] Same as Example 3.

[0118] It should be noted that, in comparing the various embodiments, Comparative Example 1 uses a traditional PCB soldering scheme, where the components are independently soldered to the PCB board, and the inductor and components are electrically connected via wires; while Comparative Example 2 uses a common heat dissipation coating spraying process, where the coating is a single material structure, and the inductor surface is covered by conventional spraying methods. Specific relevant test parameters are shown in Table 1:

[0119] Table 1: Comparison Test Table of Key Performance of Module Inductors

[0120] Comparison Projects Coating adhesion strength (MPa) Substrate deformation (μm) Steady-state thermal resistance (°C / W) On-resistance (mΩ) Example 1 22.7 8.1 12.7 42.5 Example 2 31.3 4.3 11.3 38.1 Example 3 23.5 7.7 8.2 41.7 Example 4 35.8 3.2 6.3 35.6 Comparative Example 1 18.3 12.7 18.6 58.4 Comparative Example 2 20.6 10.4 14.3 45.2

[0121] Specifically, regarding the coating adhesion strength, Example 1 showed a strength of 22.7 MPa, Comparative Example 1 showed 18.3 MPa, and Comparative Example 2 showed 20.6 MPa. Example 1 was significantly higher than the two comparative examples, indicating that the integrated soldering scheme using inductors as the conduction carrier can effectively improve the adhesion between the coating and the substrate and reduce the risk of coating peeling compared to traditional PCB soldering schemes and ordinary heat dissipation coating spraying schemes. Example 2, based on Example 1, added micro-nano texture processing, increasing the coating adhesion strength to 31.3 MPa, which is higher than Example 1, indicating that the uneven structure formed by the micro-nano texture can effectively improve the adhesion between the coating and the substrate and reduce the risk of coating peeling. Increasing the contact area between the electroplated layer and the substrate further enhances the bonding effect of the plating layer. In Example 3, a gradient thermally conductive coating was added to Example 1, and the bonding strength of the plating layer was 23.5 MPa, which was slightly higher than that of Example 1. This shows that the bottom adhesive layer of the gradient thermally conductive coating can help improve the bonding performance of the plating layer. In Example 4, the plating bonding strength reached 35.8 MPa by combining micro-nano texture processing and gradient thermally conductive coating preparation. This is higher than all examples and comparative examples, which proves that the synergistic effect of the two can form a mechanical locking effect, greatly improve the peel resistance of the plating layer and the coating, and make the bonding strength reach the optimal level.

[0122] Specifically, regarding the substrate deformation, the data for Example 1 is 8.1 μm, lower than 12.7 μm for Comparative Example 1 and 10.4 μm for Comparative Example 2. This indicates that the integrated welding solution can reduce the stress generated during welding and processing, and reduce the degree of substrate deformation, compared with traditional PCB welding and ordinary coating spraying. The substrate deformation for Example 2 is 4.3 μm, much lower than that for Example 1, indicating that the micro-nano texture structure can disperse the stress generated by thermal cycling and mechanical vibration, effectively reducing the probability of cracking and deformation of the inductor substrate and improving structural stability. The substrate deformation for Example 3 is 7.7 μm, slightly lower than that for Example 1, indicating that the gradient thermally conductive coating can form a protective layer on the substrate surface, mitigating the impact of external stress on the substrate and reducing deformation. The substrate deformation for Example 4 is 3.2 μm, the lowest value among all groups, lower than that for Examples 2 and 3. This proves that the synergy between micro-nano texture and gradient thermally conductive coating can further disperse stress, strengthen substrate protection, minimize substrate deformation, and ensure the integrity of the module structure.

[0123] Regarding steady-state thermal resistance, the data for Example 1 is 12.7℃ / W, lower than 18.6℃ / W for Comparative Example 1 and 14.3℃ / W for Comparative Example 2. This indicates that the devices in the integrated soldering scheme share the same inductor heat dissipation device, which is more direct and efficient than traditional PCB board heat dissipation and ordinary single-coating heat dissipation, and can effectively reduce thermal resistance. The steady-state thermal resistance of Example 2 is 11.3℃ / W, lower than that of Example 1, indicating that the micro-nano texture structure can increase the heat conduction area, help improve heat dissipation efficiency, and reduce thermal resistance. The steady-state thermal resistance of Example 3 drops to 8.2℃ / W, significantly lower than that of Example 1, indicating that the gradient thermally conductive coating, through layered design and the addition of functional particles, constructs an efficient and continuous heat conduction channel, which can quickly transfer the heat generated by the inductor and devices, and greatly optimize the heat dissipation effect. The steady-state thermal resistance of Example 4 is 6.3℃ / W, lower than that of Examples 2 and 3, proving that the three-dimensional thermally conductive network constructed by the micro-nano texture and the gradient thermally conductive coating can guide heat convergence and efficient conduction, achieving a superimposed improvement in heat dissipation performance, with the thermal resistance reaching its lowest level, meeting the high-efficiency heat dissipation requirements of the PCBA board.

[0124] Regarding on-resistance, the data for Example 1 is 42.5 mΩ, lower than 58.4 mΩ for Comparative Example 1 and 45.2 mΩ for Comparative Example 2. This indicates that the integrated soldering scheme reduces the conduction path between the inductor and the device, shortens the signal transmission path, effectively reduces on-resistance, and reduces energy consumption. The on-resistance for Example 2 is 38.1 mΩ, lower than that for Example 1, indicating that micro-nano texture processing can optimize the uniformity of the electroplated layer, reduce contact resistance during conduction, and further reduce on-resistance. The on-resistance for Example 3 is 41.7 mΩ, slightly lower than that for Example 1, indicating that the gradient thermally conductive coating does not affect the electrical conduction of the module and can help optimize the conductive environment, slightly reducing on-resistance. The on-resistance for Example 4 is 35.6 mΩ, lower than all examples and comparative examples, proving that the synergy between micro-nano texture and gradient thermally conductive coating can optimize heat dissipation and structural stability while further optimizing the electrical conduction path, reducing contact resistance and on-resistance, improving the electrical performance of the module, and reducing energy loss.

[0125] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a modular inductor, characterized in that, Includes the following steps: S1. Inductor selection and stripping Inductors include, but are not limited to, rectangular inductors. They can be purchased from the market or developed in-house. The size is selected according to actual needs. The solderable surface of the inductor is defined as the soldering surface, the surface parallel to the soldering surface is the bottom surface, the surface perpendicular to the soldering surface with a large area is the long side surface, and the surface perpendicular to the soldering surface with a small area is the short side surface. The inductor is placed in a customized laser stripping machine to strip the soldering surface, the short side surface, and the bottom surface, ensuring effective connection of each stripped area. The actual stripping size and the reserved area for device installation are determined according to design requirements. Only the insulating varnish layer in the designated area is removed, exposing the conductive substrate. S2, Micro-nano texturing Micro-nano texturing is performed on the surface of the inductive and conductive substrate after the paint is stripped in step S1. Plasma etching is used to process uniformly distributed circular grooves on the substrate surface. The irregular rough surface is conducive to the adhesion of the electroplating layer and the thermal conductive layer. A semi-circular protrusion is processed at the center of each circular groove. The surface of the protrusion and the inner wall of the groove are treated with a rounded transition to control the distribution spacing and size consistency of each structure. After processing, the substrate structure is kept intact, providing adhesion conditions for the subsequent electroplating layer and thermal conductive coating. S3, Electroplating and AOI Inspection After the S2 step, the inductor stripping area is subjected to multi-layer electroplating, with the outermost layer being tin-plated. After the electroplating is completed, AOI inspection equipment is used to check the flatness and parallelism of the plating layer to ensure that there are no obvious pits or protrusions. At the same time, the integrity of the stripping, the uniformity of electroplating, and the overall appearance of the inductor are also checked. S4, Solder paste printing and component mounting A special inductor solder paste printing fixture is made to fix and limit the bottom and short sides of the inductor; a special stencil is made to print solder paste on the fixing surface. After the solder paste is printed, the height, volume and area of ​​the solder paste are detected by SPI to ensure that it meets the process requirements. MOSFETs, ICs and other devices are mounted on the solder paste printing area according to the preset layout. If there are design requirements for the electrode surface, the capacitors are manually soldered after the subsequent soldering is completed. S5, Preparation of gradient thermal conductive coating A gradient thermally conductive coating was prepared in situ on the surface of the inductor after mounting in step S4 using a plasma spraying process. The coating consists of a base layer, an intermediate layer, and a surface layer. The bottom layer is a nickel-chromium bonding layer, accounting for 6%-8% of the total coating thickness, with 5 vol% spherical copper powder particles added; The intermediate layer is an aluminum nitride-silicon carbide composite layer, accounting for 70%-75% of the total coating thickness, with 12 vol% spherical aluminum nitride particles and 8 vol% flake silicon carbide particles added. The surface layer is a nano-beryllium oxide modified layer, accounting for 18%-22% of the total coating thickness, with 4 vol% dumbbell-shaped nano-beryllium oxide particles added; During coating preparation, the surface structure of the inductor is matched, filling grooves and wrapping protrusions; If step S2 has not been performed, then the surface of the flat substrate will be evenly covered. After micro-nano etching, the inductor surface has a set roughness. The electroplating layer thickness is 0.3mm, which is compatible with the surface roughness and meets the preset range. The surface grooves and protrusions formed by electroplating can be fully filled and wrapped by the gradient thermally conductive coating, which improves the coating bonding strength while ensuring the coating adhesion stability. S6, Reflow Soldering and Thermal Mounting The inductor assembly with the mounted components is sent into the reflow soldering equipment, where the solder paste is melted and solidified through temperature cycling, thus achieving electrical connection between the components and the inductor. After soldering, attach a suitable heat dissipation device, including but not limited to a copper heat sink, to one side of the inductor. Use PI double-sided tape with a thermally conductive adhesive layer or directly apply a nano-oxidation wrinkle-modified coating to the entire inductor for insulation. Apply the coating evenly to the long side, connecting the soldered side with the thermally conductive coating, the short side, and the bottom. Select a copper sheet with a thickness of 0.2-1mm and an appropriate area. The copper sheet should not be directly connected to the other four sides. The heat from the other four sides and the inductor body is transferred to the copper sheet by the PI double-sided tape with a thermally conductive adhesive layer, and then the copper sheet dissipates heat to the environment. This ensures that the heat dissipation device is tightly attached to the inductor or the gradient thermally conductive coating, forming a complete heat conduction path to transfer the heat generated by the inductor and the device. S7. Testing and Packaging Customized testing equipment is used to conduct electrical performance and appearance inspections on the modules to verify that the electrical performance meets the standards and that there are no defects in the appearance. After passing the inspection, the modules are taped and packaged, boxed, and labeled with product model, specifications, and production date to complete the finished product preparation.

2. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S1, the customized laser paint stripping machine adjusts the paint stripping parameters according to the selected inductor size. The area size and connection status are monitored in real time during the paint stripping process to ensure that there is no missed or over-stripping, and the conductive substrate is uniformly exposed, providing good surface conditions for the electroplating process. The rectangular inductor selection must meet the requirements of welding, electroplating and heat dissipation device mounting processes. After purchase, the inductor is pre-treated to remove surface dust and impurities without damaging the insulating varnish layer.

3. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S2, the vacuum level in the reaction chamber is controlled during the plasma etching process. The etching rate is adjusted by adjusting the plasma density. The processed circular groove and semi-circular protrusion have the same size. There are no sharp corners or burrs at the arc transition. After processing, debris and impurities are removed to ensure the cleanliness of the substrate surface, increase the contact area between the electroplated layer and the substrate, and help improve the heat dissipation effect.

4. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S3, multi-layer electroplating is carried out according to a preset plating order and thickness. The outermost layer is tin-plated to ensure soldering compatibility. The AOI inspection equipment accurately identifies defects through image acquisition and analysis technology, generates inspection result files, and unqualified products are transferred to the rework process to avoid affecting the module integration effect and performance.

5. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S4, the positioning accuracy of the dedicated fixture is adapted to the inductor size, and it is made of wear-resistant material so as not to damage the inductor surface during fixation; the size and distribution of the dedicated stencil mesh correspond to the soldering points, and the thickness of the stencil mesh matches the thickness of the solder paste printing; when the SPI test result exceeds the preset range, the printing parameters are adjusted; and a high-precision pick-and-place machine is used for device placement to ensure that the pins are accurately aligned with the solder paste coating area.

6. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S5, the addition of particles to each layer of the coating is achieved by a combination of mechanical stirring and ultrasonic dispersion to ensure uniform particle distribution without agglomeration. During the preparation process, the coating thickness is monitored in real time, and the spraying parameters are adjusted to control the thickness of each layer. When filling the groove, it is ensured that the inner wall and the raised surface are completely covered without gaps or bubbles, thereby reducing the resistance to heat transfer.

7. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S6, the reflow soldering process is controlled according to a preset temperature curve, including the heating, holding, and cooling stages. When manually soldering capacitors, an adapter is used to control the soldering temperature and time to avoid damaging the device and the inductor substrate. Before mounting the heat dissipation device, the surface of the inductor or coating is cleaned, and uniform pressure is applied to ensure full contact without any local gaps. The mounting position is fixed on one side of the inductor to ensure a smooth heat conduction path.

8. The method for manufacturing a modular inductor according to claim 1, characterized in that, In step S7, the electrical performance testing of the customized testing equipment includes items such as conduction resistance, insulation resistance, and withstand voltage; the appearance inspection includes items such as structural integrity, accuracy of device installation position, and no surface damage; tape and reel packaging ensures that the module is not damaged during transportation; and the label information facilitates product traceability and management.

Images