Plastic package inductance module based on double plating layers, manufacturing method and power supply device

Abstract

The invention relates to the technical field of inductor plastic package, in particular to a plastic package inductor module based on double plating layers, a manufacturing method and a power supply device. The metal coating is arranged on the surface of the power conductor, current distribution is optimized, conductive efficiency is improved, contact resistance is reduced by 40% compared with that of a traditional copper coating, stability of the inductance module is improved, and the problems that in an existing plastic package inductance technology, a metal oxide layer is prone to being generated on the surface of the power conductor in a high-temperature and high-humidity environment, and the service life of the power conductor is prolonged are solved. And the long-term use stability is influenced. On the other hand, according to the frequency of a signal needing to be transmitted, signal transmission conductors of different structures are arranged in other areas, except for the exposed surface of the power conductor, of the outer surface of the plastic package structure, so that the transmission loss of the signal is reduced, and different signal transmission conductors can be arranged according to the types of different signals; and the transmission requirements of high-speed digital signals are met.

Description

Technical Field

[0001] This invention relates to the field of inductor encapsulation technology, and in particular to a double-layer encapsulated inductor module, its manufacturing method, and its power supply device. Background Technology

[0002] In existing plastic-encapsulated inductor technology, the structure is mainly integrated by wrapping the magnetic core and conductor with plastic material; however, when facing high power density and high frequency signal transmission scenarios, the following shortcomings still exist: (1) In the traditional scheme, the exposed area of ​​the power conductor used to transmit power is usually not metal plated or a single copper plated. This is prone to generating a metal oxide layer in high temperature and high humidity environment, resulting in an average annual increase of 15%-20% in contact resistance. Especially under high current (e.g., current > 10A) conditions, the electromigration phenomenon of copper plated will cause uneven plate thickness, thereby causing local overheating (temperature rise ≥ 35K), affecting the stability of long-term use.

[0003] (2) Signal transmission relies on a uniform metal conductor on the surface of the encapsulation material. The material and plating structure have not been optimized for different signal types. For example, for high-frequency signals above 1 GHz, the skin effect of the copper plating will cause the signal loss to reach more than 1 dB / cm. At the same time, the electromagnetic coupling phenomenon between the copper plating and the power conductor will introduce crosstalk of ≥30 dB, thus affecting signal integrity.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to address the issue that in existing plastic-encapsulated inductor technology, the exposed area of ​​the power conductor that transmits power is usually not plated with metal or uses a single copper plating layer, which easily forms a metal oxide layer in high temperature and high humidity environments, affecting the stability of long-term use, and the issue that the signal transmission depends on a uniform metal conductor on the plastic-encapsulated surface, without optimizing the materials and structure for different signal types.

[0006] The present invention adopts the following technical solution: In a first aspect, a plastic-encapsulated inductor module based on a double-layer coating is provided, including an inductor component 1, a plastic-encapsulated structure 2, a power conductor 3, and a signal transmission conductor 4; the plastic-encapsulated structure 2 is disposed on the outer peripheral surface of the inductor component 1. A metal plating layer 5 is provided on the surface of the power conductor 3; The signal transmission conductor 4 is disposed on the first surface of the encapsulation structure 2 in areas other than the exposed surface of the power conductor 3, and the structure of the signal transmission conductor 4 is configured according to the frequency of the signal to be transmitted. The first surface is the side surface on which the power conductor 3 is disposed.

[0007] Preferably, the inductor assembly 1 includes a magnetic core 10 and a winding 11, wherein the winding 11 is disposed on the surface of the magnetic core 10; or, the winding 11 is wrapped by the magnetic core 10 and both ends of the winding 11 are exposed from the surface of the magnetic core 10. The encapsulation structure 2 is encapsulated on the outer peripheral surface of the magnetic core 10, and the two ends of the winding 11 are exposed from the first end face and the second end face of the encapsulation structure 2, respectively, to form electrical pads for connection with external circuits.

[0008] Preferably, the inner surface of the encapsulation structure 2 is designed to be fully fitted with the outer peripheral surface of the magnetic core 10, or a heat dissipation gap of 0.1mm-0.3mm is reserved between the inner surface of the encapsulation structure 2 and the outer peripheral surface of the magnetic core 10, and the heat dissipation gap is filled with thermal grease or air.

[0009] Preferably, the power conductor 3 is disposed on the outer peripheral surface of the magnetic core 10, and the top end, bottom end and the side near the outer side of the encapsulation structure 2 of the power conductor 3 are exposed; wherein, the exposed area accounts for 30%-50% of the surface area of ​​the power conductor 3.

[0010] Preferably, the metal coating 5 includes at least one metal layer, and each metal layer includes at least two segmented metal regions; The spacing between the segmented metal areas ranges from 0.1mm to 5mm; The thickness of each metal layer ranges from 0.1 μm to 1 μm; The horizontal offset between two adjacent segmented metal regions ranges from 0.2mm to 0.5mm, and the vertical offset ranges from 0.1mm to 0.3mm, in order to form a stable three-dimensional current channel and improve conductivity.

[0011] Preferably, when the frequency of the signal to be transmitted is less than or equal to 100MHz, the signal transmission conductor 4 is configured with a planar plating layer, the thickness of the planar plating layer is 0.1μm-10μm, and the width of the signal trace is 0.05mm-5mm; When the frequency of the signal to be transmitted is higher than 100MHz, the signal transmission conductor 4 is formed by a microstrip line structure or a coplanar waveguide structure. When the frequency of the signal to be transmitted is higher than or equal to 1 GHz, the signal transmission conductor 4 is formed by a stripline structure or a shielded microstrip line structure.

[0012] Preferably, the metal plating layer 5 includes a nickel plating layer, a gold plating layer and a passivation layer stacked together, and the nickel plating layer is disposed on the outer exposed surface of the power conductor 3.

[0013] Preferably, the minimum distance between the metal plating layer 5 and the signal transmission conductor 4 is greater than or equal to 0.5 mm; The metal plating layer 5 is connected to the grounding terminal of the signal transmission conductor 4 to improve signal integrity and anti-interference capability.

[0014] Secondly, a method for manufacturing a double-plated molded inductor module is provided, for manufacturing the double-plated molded inductor module as described in the first aspect, comprising: The molding structure 2 is disposed on the outer peripheral surface of the inductor assembly 1, the power conductor 3 is disposed on the first surface of the molding structure 2, and a metal plating layer 5 is plated on the surface of the power conductor 3; Based on the frequency of the signal to be transmitted, the signal transmission conductor 4 is provided on the first surface of the encapsulated structure 2 in areas other than the exposed surface of the power conductor 3 to obtain the inductor module.

[0015] Thirdly, a power supply device is provided, comprising at least one double-plated encapsulated inductor module as described in the first aspect.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention optimizes current distribution and improves conductivity by employing a multi-layer segmented metal structure to deposit a metal plating layer 5 on the surface of the power conductor 3. This reduces contact resistance by 40% compared to traditional copper plating, enhancing the stability of the inductor module. It also solves the problem in existing plastic-encapsulated inductor technology where a metal oxide layer easily forms on the surface of the power conductor 3 under high temperature and humidity conditions, affecting long-term stability. Furthermore, depending on the frequency of the signal to be transmitted, signal transmission conductors 4 with different structures are set in areas other than the exposed surface of the power conductor 3 on the outer surface of the plastic-encapsulated structure 2, reducing signal transmission loss. Different signal transmission conductors 4 can be set according to different signal types to meet the transmission requirements of high-speed digital signals. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of the structure of an inductor module provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an electrical solder pad provided in an embodiment of the present invention; Figure 3 This is a top view of an inductor module provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a metal coating 5 provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a microstrip line structure provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a coplanar waveguide structure provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of a stripline structure provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of a shielded microstrip line structure provided in an embodiment of the present invention; Figure 9 This is a schematic flowchart of a method for manufacturing a plastic-encapsulated inductor module based on a double-layer coating, provided by an embodiment of the present invention.

[0019] In all the accompanying drawings, the same reference numerals denote the same structure, wherein: Inductor assembly 1, magnetic core 10, winding 11, plastic encapsulation structure 2, power conductor 3, signal transmission conductor 4, metal plating 5. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0022] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0023] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling," "wireless connection," etc. The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0024] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Example 1: To address the problems of existing technologies, this embodiment provides a molded inductor module based on a dual-layer coating. In one embodiment, such as... Figure 1 As shown, the device includes an inductor assembly 1, a molding compound 2, a power conductor 3, and a signal transmission conductor 4. The molding compound 2 is disposed on the outer peripheral surface of the inductor assembly 1. A metal plating layer 5 is disposed on the surface of the power conductor 3 to optimize current distribution and improve conductivity. The signal transmission conductor 4 is disposed on the first surface of the molding compound 2, excluding the exposed surface of the power conductor 3, and its structure is configured according to the frequency of the signal to be transmitted. The signal transmission conductor 4 is used to transmit signals. The first surface is the side surface on which the power conductor 3 is disposed.

[0026] In one embodiment, refer to Figure 1The inductor assembly 1 includes a magnetic core 10 and a winding 11, the winding 11 being disposed on the surface of the magnetic core 10; the encapsulation structure 2 is encapsulated on the outer peripheral surface of the magnetic core 10. Alternatively, in other embodiments, the winding 11 is wrapped by the magnetic core 10 and both ends of the winding 11 are exposed from the surface of the magnetic core 10; this structure is not illustrated.

[0027] In practical applications, the inductor module has corresponding circuit boards at its upper and lower ends. The two ends of the winding 11, power conductor 3, and signal transmission conductor 4 are used to connect the two circuit boards, respectively. The magnetic core 10 and winding 11 are used for energy storage, the power conductor 3 is used for current transmission, and the signal transmission conductor 4 is used for control signal transmission. Furthermore, the power conductor 3 is used to transmit large currents, and the signal transmission conductor 4 is used to transmit small currents or control signals.

[0028] In one embodiment, the magnetic core 10 can be made of ferrite (such as Ni-Zn ferrite, suitable for high-frequency applications, with a loss ≤500mW / cm). 3 The winding can be made of flat copper wire (1mm² cross-section) or alloy powder (such as Fe-Si-Al alloy powder, suitable for high current scenarios, saturation magnetic flux density ≥1.2T), with geometric shapes including cuboids, cylinders, etc., and can be open or closed structures selected according to the magnetic circuit design. 2 -5mm 2 ) winding, in one embodiment, such as Figure 2 As shown, the two ends of the winding 11 are exposed from the first end face and the second end face of the encapsulation structure 2, respectively, to form electrical pads for connection with external circuits.

[0029] In one embodiment, the molding compound 2 is made of high-temperature resistant epoxy molding compound, which can be directly molded onto the outer peripheral surface of the magnetic core 10, or it can be injection molded into an independent integrated structure and then assembled onto the inductor assembly 1. The thickness of the molding compound 2 ranges from 0.5mm to 2mm, and the outer surface roughness Ra≤1.6μm. Furthermore, the outer surface of the molding compound 2 is continuous without segmentation, and positioning bosses or grooves can be designed according to the installation requirements of the inductor module to facilitate automated mounting.

[0030] In one embodiment, refer to Figure 1The power conductor 3 is arranged parallel to the long axis of the magnetic core 10 (corresponding to a cuboid magnetic core) or around the circumference of the magnetic core 10 (corresponding to a cylindrical magnetic core). The distance between the axis of the power conductor 3 and the axis of the magnetic core 10 is ≤2mm to ensure a magnetic field coupling efficiency ≥90%. The exposed outer surface of the power conductor 3 is flush with the outer surface of the encapsulation structure 2, with a deviation ≤±0.02mm. The signal transmission conductor 4 is spatially isolated from the power conductor 3 by the encapsulation structure 2, with a minimum distance ≥0.5mm, to avoid short circuits between the signal and power paths. In one embodiment, the power conductor 3 is disposed on the outer peripheral surface of the magnetic core 10, and the top, bottom, and side near the outer side of the encapsulation structure 2 of the power conductor 3 are exposed; wherein the exposed area accounts for 30%-50% of the surface area of ​​the power conductor 3.

[0031] In one embodiment, both the power conductor 3 and the signal transmission conductor 4 are made of highly conductive materials, for example, both are made of copper. The metal plating 5 deposited on the surface of the power conductor 3 can be a gold plating or a composite layer formed by gold and other highly conductive materials. The metal plating 5 has good conductivity and a low oxidation rate.

[0032] In one embodiment, the metal plating layer 5 is electroplated on the outer exposed surface of the power conductor 3. The metal plating layer 5 includes a nickel plating layer, a gold plating layer, and a passivation layer stacked together. The nickel plating layer is disposed on the outer exposed surface of the power conductor 3. The thickness of the nickel plating layer is 2μm-3μm, the thickness of the gold plating layer is 1μm-3μm, and the thickness of the passivation layer is ≤0.1μm.

[0033] In one embodiment, a chemical nickel plating + electroplating gold method can be used to sequentially form a nickel plating layer and a gold plating layer. The gold layer thickness is 1μm-3μm. The surface is treated with anti-oxidation to form a passivation layer. The contact resistance is ≤5mΩ. After a salt spray test (96 hours), the resistance change rate is ≤5%.

[0034] In this embodiment, because a metal plating layer 5 is deposited on the surface of the power conductor 3, the contact resistance is reduced by 40% compared to the traditional copper plating layer (from 8mΩ to 4.8mΩ), the oxidation resistance life is extended by 3 times (the salt spray test compliance time is increased from 500 hours to 1500 hours), and it supports continuous 50A high current transmission (temperature rise ≤30K). This improves the reliability of high current transmission.

[0035] In one embodiment, the structure of the signal transmission conductor 4 can be designed according to the required signal frequency. The signal transmission conductor 4 can be a planar plating layer (for low-frequency signals) or a conductive layer of a microstrip line structure (for high-frequency signals, with a characteristic impedance controlled at 50±5Ω), with a thickness of 5μm-10μm. A continuous conductive layer is formed by electroplating to support flexible layout of signal line paths (e.g., differential pairs, ground planes, etc.).

[0036] To reduce the overall size of the inductor module, in one embodiment, the inner surface of the molding compound 2 is designed to be completely flush with the outer peripheral surface of the magnetic core 10. Where the surfaces of the magnetic core 10 and the molding compound 2 are absolutely flat and without gaps, heat can be quickly conducted through direct contact without the need for additional filler material, resulting in minimal thermal resistance. This solution eliminates the need for pre-reserved gaps, saving space and reducing the overall size of the inductor module, making it suitable for highly integrated designs.

[0037] However, the surface microstructure of the magnetic core 10 (such as ferrite or iron powder core) and the encapsulation structure 2 (such as epoxy resin) is uneven (such as scratches, bumps). The magnetic core 10 and the encapsulation structure 2 have different coefficients of thermal expansion (for example, the coefficient of thermal expansion of ferrite is ≈6ppm / K, and the coefficient of thermal expansion of epoxy resin is ≈50ppm / K). Stress is easily generated when the temperature changes, which may cause the encapsulation structure 2 to crack or the magnetic core 10 to deform.

[0038] Therefore, taking into account the heat dissipation problem of the inductor module and its miniaturization design, in one embodiment, such as Figure 3 As shown, a 0.1mm-0.3mm heat dissipation gap (shown as X in the figure) is reserved between the inner surface of the molding compound 2 and the outer peripheral surface of the magnetic core 10. This gap is filled with thermally conductive silicone grease or air to reduce thermal resistance. Compared to air, thermally conductive silicone grease can fill the microscopic uneven areas on the surfaces of the magnetic core 10 and the molding compound 2, significantly reducing interface thermal resistance by 15%-25%. The 0.1mm-0.3mm heat dissipation gap buffers the expansion differences between the magnetic core 10 and the molding compound 2 caused by temperature differences, preventing structural stress concentration and improving heat dissipation efficiency, allowing heat to be quickly transferred from the magnetic core 10 to the molding compound 2. The heat dissipation gap design between the molding compound 2 and the magnetic core 10, combined with thermally conductive materials (thermally conductive silicone grease or air), extends the operating temperature range of the inductor module to -55℃ to 150℃, adapting to harsh environments such as automotive electronics and industrial control.

[0039] In one embodiment, with Figure 2 The difference is, Figure 3 Windings 11 are provided on both sides of the central magnetic core 10.

[0040] The following section will provide a detailed explanation of how the metal coating 5 is applied through a multi-layered segmented metal structure.

[0041] To improve the conductivity efficiency of the power conductor 3, in one embodiment, such as Figure 4 As shown, the metal coating 5 includes at least one metal layer, and each metal layer includes at least two segmented metal regions; the spacing between the segmented metal regions ranges from 0.1 mm to 5 mm; the thickness of each metal layer ranges from 0.1 μm to 1 μm; the horizontal offset between two adjacent segmented metal regions ranges from 0.2 mm to 0.5 mm, and the vertical offset ranges from 0.1 mm to 0.3 mm, so as to form a stable three-dimensional current channel and improve conductivity.

[0042] The metal layer can be a gold plating or a composite layer formed by gold and other highly conductive materials.

[0043] Finite element analysis can be used to simulate current distribution and adjust the spacing between segmented metal regions to concentrate current in the metal layer, maximizing the skin effect and improving conductivity. Too small a spacing leads to current congestion, while too large a spacing reduces the skin effect. Preferably, the spacing between the segmented metal regions is in the range of 0.1mm-5mm. Within this range, current congestion caused by insufficient spacing is effectively avoided while ensuring a sufficiently strong skin effect, thus significantly improving conductivity. More preferably, when the spacing between the segmented metal regions is 0.5mm-2mm, the current concentration in the metal layer is optimal, the skin effect is maximized, and the conductivity is improved to its best potential.

[0044] In one embodiment, in a multi-layered segmented metal structure, the metal layers of different layers are staggered to form a three-dimensional current channel, thereby further optimizing current distribution and reducing resistance. Specifically, in the multi-layered segmented metal structure, the thickness of each layer can be adjusted according to actual application requirements. Preferably, the thickness of each gold-plated layer is in the range of 0.1μm-1μm to ensure both good conductivity and effective cost control. In one embodiment, the staggering of the metal layers between different layers can be achieved through a regular staggered arrangement. For example, the horizontal distance between two adjacent metal layers is 0.2mm-0.5mm, and they are also appropriately offset in the vertical direction by 0.1mm-0.3mm, thereby forming a stable and efficient three-dimensional current channel.

[0045] When fabricating multi-layered segmented metal structures, electroplating can be used. Precise gold deposition in each layer can be achieved by controlling parameters such as electroplating time and current density. The electroplating time can be controlled between 10 and 30 minutes, and the preferred current density is 0.5 A / dm³. 2-2A / dm 2 This ensures the uniformity and quality of the metal coating 5, thereby further optimizing the current distribution and effectively reducing resistance.

[0046] The design of the signal transmission conductor 4 in this embodiment will be described next. The frequency of the signal to be transmitted is divided into three ranges, including below or equal to 100MHz (corresponding to low frequency), 100MHz-1GHz (corresponding to medium frequency), and above or equal to 1GHz (corresponding to high frequency).

[0047] In one embodiment, when the frequency of the signal to be transmitted is less than or equal to 100MHz, the signal transmission conductor 4 is configured with a planar plating layer, the thickness of which is 0.1μm-10μm and the width of the signal trace is 0.05mm-5mm.

[0048] For signals with frequencies below or equal to 100MHz, a planar plating structure is used. The planar plating has the advantages of simple structure and low manufacturing cost, and can meet the transmission requirements of low-frequency signals. The shape and width of the signal trace can be adjusted according to actual application requirements to optimize signal transmission characteristics. Preferably, the thickness of the planar plating is 0.1μm-10μm, more preferably 0.5μm-5μm. The width of the signal trace is preferably 0.05mm-5mm, more preferably 0.1mm-2mm. In one embodiment, the shape of the signal trace is a straight line, a polygonal line, or a microstrip line. The deviation between the length of the straight trace and the signal transmission distance is controlled within ±5%. The bending angle of the polygonal trace is preferably 45° or 90°. The characteristic impedance of the microstrip line is preferably 50Ω or 75Ω.

[0049] In one embodiment, when the frequency of the signal to be transmitted is higher than 100MHz, the signal transmission conductor 4 is formed by a microstrip line structure or a coplanar waveguide structure.

[0050] For signals with frequencies higher than 100MHz, microstrip lines (such as...) are used. Figure 5 (as shown) or coplanar waveguide structures (such as) Figure 6 (As shown in the figure). Where W is the width of the metal line used for signal transmission, and h is the height of the dielectric substrate. The microstrip line and coplanar waveguide structure can precisely control the characteristic impedance, reduce signal reflection, and improve signal integrity. The dielectric layer of the microstrip line structure can adopt a molding compound structure 2. By precisely controlling the thickness (0.1mm-0.5mm) and dielectric constant (εr=3.0-4.5) of the molding compound structure 2, precise matching of the characteristic impedance (50Ω±5Ω) can be achieved. The coplanar waveguide structure has better grounding performance and can effectively suppress common-mode interference.

[0051] In one embodiment, when the frequency of the signal to be transmitted is higher than or equal to 1 GHz, the signal transmission conductor 4 is formed by a stripline structure or a shielded microstrip line structure.

[0052] For signals with frequencies higher than or equal to 1 GHz, a stripline structure (such as...) is used. Figure 7 (as shown) or shielded microstrip line structure (such as Figure 8 (As shown). Stripline structures and shielded microstrip line structures provide stronger shielding effects, reducing signal radiation and crosstalk. Stripline structures completely enclose the signal line in a ground layer, offering excellent shielding performance, with a shielding effect of -60dB. Shielded microstrip line structures add a ground layer above the microstrip line, forming a shield that effectively suppresses electromagnetic interference and reduces crosstalk by ≥40dB.

[0053] In one embodiment, the signal transmission conductor 4 includes a signal layer, a ground layer, and a power layer. The signal layer is used to transmit signals, the ground layer is used to provide a reference ground, and the power layer is used to provide power for signal transmission. The signal transmission conductor 4 is configured with a multilayer interconnect structure. The signal layer is used to transmit high-speed signals, and optimized routing design reduces signal loss and crosstalk. The ground layer provides a stable reference ground, suppresses common-mode interference, and improves signal integrity. The power layer provides power for signal transmission, reducing the impact of power supply noise on the signal. Interlayer interconnection uses via technology, preferably blind vias or buried vias, to reduce the impact of vias on the signal. The via diameter is ≤0.2mm, and the via spacing is ≥0.4mm.

[0054] To avoid short circuits between the signal transmission path and the power transmission path, in one embodiment, the minimum spacing between the metal plating layer 5 and the signal transmission conductor 4 is greater than or equal to 0.5 mm.

[0055] To improve signal integrity and anti-interference capability, in one embodiment, the metal plating layer 5 and the grounding terminal of the signal transmission conductor 4 are connected to improve signal integrity and anti-interference capability.

[0056] In summary, after applying the metal plating layer 5 using the aforementioned multi-layer segmented metal structure, the large current (10A-50A) from the external power supply flows in through the top and bottom pads of the power conductor 3. The metal plating layer 5 exhibits an extremely low oxidation rate (annual weight gain ≤0.1μg / cm³). 2 High conductivity ensures long-term stability of the contact interface; at the same time, the design of power conductor 3 with a thickness of ≥1mm controls the DC resistance to below 10mΩ, and with the heat dissipation gap, the temperature rise under high current is ≤25K.

[0057] On the other hand, the signals to be transmitted (such as pulse width modulation signals and current feedback signals) are transmitted through the signal transmission conductor 4 on the surface of the encapsulation structure 2. Its low skin depth characteristics (approximately 6.6 μm at 10 MHz) reduce the loss of high-frequency signal transmission, and the high insulation of the encapsulation structure 2 (dielectric loss tangent ≤ 0.02) suppresses signal attenuation. Simultaneously, the spatial isolation design between the signal transmission path and the power transmission path enables a crosstalk rejection ratio of over 40 dB.

[0058] This embodiment optimizes current distribution and improves conductivity by using a multi-layer segmented metal structure to deposit a metal plating layer 5 on the surface of the power conductor 3. This reduces contact resistance by 40% compared to traditional copper plating, improving the stability of the inductor module. It also solves the problem in existing plastic-encapsulated inductor technology where a metal oxide layer easily forms on the surface of the power conductor 3 under high temperature and humidity conditions, affecting long-term stability. On the other hand, depending on the frequency of the signal to be transmitted, signal transmission conductors 4 with different structures are set in other areas of the outer surface of the plastic-encapsulated structure 2, excluding the exposed surface of the power conductor 3. This reduces signal transmission loss and allows for the setting of different signal transmission conductors 4 according to different signal types, meeting the requirements for high-speed digital signal transmission.

[0059] Example 2: This embodiment proposes a method for fabricating a double-layer molded inductor module. This method is used to fabricate the double-layer molded inductor module as described in Embodiment 1. In one embodiment, as shown... Figure 9 As shown, the manufacturing method includes: Step 101: The molding structure 2 is disposed on the outer peripheral surface of the inductor assembly 1, the power conductor 3 is disposed on the first surface of the molding structure 2, and a metal plating layer 5 is plated on the surface of the power conductor 3.

[0060] In one embodiment, the power conductor 3 is configured as follows: a precision injection mold (accuracy grade IT6) is used, with the cavity surface plated with hard chrome (thickness 5μm-10μm) to ensure a dimensional tolerance of ±0.05mm for the encapsulated structure 2; a conductor positioning groove is built into the mold to match the cross-sectional shape of the power conductor 3, with a positioning accuracy of ±0.02mm; the melting temperature of the encapsulated structure 2 is set to 180℃-220℃ (epoxy encapsulant), the injection pressure is 5MPa-15MPa, the holding time is 10s-30s, the cooling temperature is 50℃-80℃, and the cooling time is 60-120s; the gate position is optimized through mold flow analysis to avoid cavitation and weld lines, ensuring that the encapsulated structure 2 is defect-free and has a density ≥1.8g / cm³. 3 Water absorption rate ≤0.1% (25℃, 24h).

[0061] The surface of the power conductor 3 is polished (roughness Ra≤1.6μm) and chemically cleaned (to remove oil and oxide film). The welding areas at both ends are nickel-plated (thickness 5μm-8μm) to enhance wettability with solder. Before the encapsulation structure 2 is cured (during the gel time), the pre-treated power conductor 3 is embedded into the preset slot of the mold by a robotic arm to ensure that the exposed surface is flush with the mold parting surface. The position is calibrated in real time using a vision positioning system (accuracy ±0.01mm). Alternatively, the power conductor 3 can be completely placed inside the encapsulation structure 2 and then the surface is polished to expose the sides of the power conductor 3.

[0062] In one embodiment, the growth method of the metal coating 5 includes: using electroless nickel plating as a base layer, employing a nickel sulfamate system, a temperature of 50℃-60℃, a pH value of 4.5-5.5, a deposition rate of 1-2μm / 10min, to form a dense nickel layer (porosity ≤5%).

[0063] The growth method for each metal layer includes: using a sulfite gold plating solution with a current density of 0.5 A / dm³. 2 -2A / dm 2 Temperature 40℃-50℃, time 5min-15min, gold layer purity ≥99.9%, surface hardness ≥50HV.

[0064] Finite element analysis can be used to simulate current distribution and adjust the spacing between segmented metal regions to concentrate current in the metal layer, maximizing the skin effect and improving conductivity. Too small a spacing leads to current congestion, while too large a spacing reduces the skin effect. Preferably, the spacing between the segmented metal regions is in the range of 0.1mm-5mm. Within this range, current congestion caused by insufficient spacing is effectively avoided while ensuring a sufficiently strong skin effect, thus significantly improving conductivity. More preferably, when the spacing between the segmented metal regions is 0.5mm-2mm, the current concentration in the metal layer is optimal, the skin effect is maximized, and the conductivity is improved to its best potential.

[0065] In one embodiment, in a multi-layered segmented metal structure, the metal layers of different layers are staggered to form a three-dimensional current channel, thereby further optimizing current distribution and reducing resistance. Specifically, in the multi-layered segmented metal structure, the thickness of each layer can be adjusted according to actual application requirements. Preferably, the thickness of each gold-plated layer is in the range of 0.1μm-1μm to ensure both good conductivity and effective cost control. In one embodiment, the staggering of the metal layers between different layers can be achieved through a regular staggered arrangement. For example, the horizontal distance between two adjacent metal layers is 0.2mm-0.5mm, and they are also appropriately offset in the vertical direction by 0.1mm-0.3mm, thereby forming a stable and efficient three-dimensional current channel.

[0066] When fabricating multi-layered segmented metal structures, electroplating can be used. Precise gold deposition in each layer can be achieved by controlling parameters such as electroplating time and current density. The electroplating time can be controlled between 10 and 30 minutes, and the preferred current density is 0.5 A / dm³. 2 -2A / dm 2 This ensures the uniformity and quality of the metal coating 5, thereby further optimizing the current distribution and effectively reducing resistance.

[0067] Step 102: Based on the required frequency of the signal to be transmitted, the signal transmission conductor 4 is provided on the first surface of the encapsulated structure 2 in areas other than the exposed surface of the power conductor 3 to obtain the inductor module.

[0068] The first surface is the side surface on which the power conductor 3 is disposed.

[0069] In one embodiment, when the frequency of the signal to be transmitted is less than or equal to 100MHz, the signal transmission conductor 4 is provided by a planar plating layer, the thickness of which is 0.1μm-10μm and the width of the signal trace is 0.05mm-5mm.

[0070] The signal transmission conductor 4 is configured as follows: the outer surface of the encapsulated structure 2 is roughened (roughness Ra is increased to 3.2 μm), and then activated by an acidic copper chloride solution to form a micro-anchoring structure; a copper sulfate electrolyte (copper ion concentration 80-120 g / L) is used, with a peak current density of 1-3 A / dm³. 2 With a duty cycle of 30%-70%, a frequency of 100-1000Hz, and a deposition rate of 2-5μm / 10min, a copper layer with refined grains (average grain size ≤5μm) is formed.

[0071] For signals with frequencies below or equal to 100MHz, a planar plating structure is used. The planar plating has the advantages of simple structure and low manufacturing cost, and can meet the transmission requirements of low-frequency signals. The shape and width of the signal trace can be adjusted according to actual application requirements to optimize signal transmission characteristics. Preferably, the thickness of the planar plating is 0.1μm-10μm, more preferably 0.5μm-5μm. The width of the signal trace is preferably 0.05mm-5mm, more preferably 0.1mm-2mm. In one embodiment, the shape of the signal trace is a straight line, a polygonal line, or a microstrip line. The deviation between the length of the straight trace and the signal transmission distance is controlled within ±5%. The bending angle of the polygonal trace is preferably 45° or 90°. The characteristic impedance of the microstrip line is preferably 50Ω or 75Ω.

[0072] In one embodiment, when the frequency of the signal to be transmitted is higher than 100MHz, the signal transmission conductor 4 is set by a microstrip line structure or a coplanar waveguide structure.

[0073] Among them, reference Figure 5 and Figure 6 For signals with frequencies higher than 100MHz, microstrip lines or coplanar waveguide structures are used. These structures allow for precise control of characteristic impedance, reducing signal reflection and improving signal integrity. The dielectric layer of the microstrip line structure can be a plastic-encapsulated structure 2. By precisely controlling the thickness (0.1mm-0.5mm) and dielectric constant (εr=3.0-4.5) of the encapsulated structure 2, precise matching of characteristic impedance (50Ω±5Ω) can be achieved. The coplanar waveguide structure offers better grounding performance and effectively suppresses common-mode interference.

[0074] In one embodiment, when the frequency of the signal to be transmitted is higher than or equal to 1 GHz, the signal transmission conductor 4 is configured using a stripline structure or a shielded microstrip line structure.

[0075] Among them, reference Figure 7 and Figure 8 For signals with frequencies higher than or equal to 1 GHz, stripline or shielded microstrip line structures are used. Stripline and shielded microstrip line structures provide stronger shielding, reducing signal radiation and crosstalk. Stripline structures completely enclose the signal line in a ground plane, offering excellent shielding performance up to -60 dB. Shielded microstrip line structures add a ground plane above the microstrip line, forming a shield that effectively suppresses electromagnetic interference and reduces crosstalk by ≥40 dB.

[0076] In one embodiment, the signal transmission conductor 4 includes a signal layer, a ground layer, and a power layer; the signal layer is used to transmit signals, the ground layer is used to provide a reference ground, and the power layer is used to provide power for signal transmission; wherein the signal layer, the ground layer, and the power layer are connected to an external circuit through blind vias or buried vias.

[0077] The signal transmission conductor 4 is constructed using a multi-layer interconnect structure. The signal layer transmits high-speed signals and employs optimized routing design to reduce signal loss and crosstalk. The ground layer provides a stable reference ground, suppresses common-mode interference, and improves signal integrity. The power layer provides power for signal transmission, reducing the impact of power supply noise on the signal. Inter-layer interconnection utilizes via technology, preferably blind or buried vias, to minimize the impact of vias on the signal. The via diameter is ≤0.2mm, and the via spacing is ≥0.4mm.

[0078] After the metal plating layer 5 and the signal transmission conductor 4 are set, post-processing steps are required, including removing the overflow material at the edge of the plastic encapsulation structure 2 by sandblasting or chemical polishing to ensure that the external dimensions meet the design requirements; measuring the thickness of the plating layer with an X-ray fluorescence spectrometer (accuracy ±0.1μm), observing the surface morphology of the plating layer with a scanning electron microscope, and using the cross-cut adhesion test to ensure that no plating layer peels off.

[0079] In one embodiment, during the fabrication of the signal transmission conductor 4, a laser can be used to irradiate the surface of the encapsulated structure 2 to activate specific areas, thereby enabling them to metallize. Preferably, the laser wavelength range is 355nm-1064nm, the pulse width range is 10ns-100ns, the repetition frequency range is 1kHz-100kHz, and the laser energy density range is 0.1J / cm². 2 -10J / cm 2 The surface roughness Ra of the activated region of the encapsulated structure 2 ranges from 0.1 μm to 10 μm. The linewidth accuracy of the gold-plated pattern can be controlled within ±5 μm, and the resolution can reach 10 μm to 100 μm.

[0080] This embodiment optimizes current distribution and improves conductivity by using a multi-layer segmented metal structure to deposit a metal plating layer 5 on the surface of the power conductor 3. This reduces contact resistance by 40% compared to traditional copper plating, improving the stability of the inductor module. It also solves the problem in existing plastic-encapsulated inductor technology where a metal oxide layer easily forms on the surface of the power conductor 3 under high temperature and humidity conditions, affecting long-term stability. On the other hand, depending on the frequency of the signal to be transmitted, signal transmission conductors 4 with different structures are set in other areas of the outer surface of the plastic-encapsulated structure 2, excluding the exposed surface of the power conductor 3. This reduces signal transmission loss and allows for the setting of different signal transmission conductors 4 according to different signal types, meeting the requirements for high-speed digital signal transmission.

[0081] For the specific structure of the inductor module, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0082] Example 3: This embodiment proposes a power supply device, which in one embodiment includes at least one plastic-encapsulated inductor module based on a double-layer coating as described in Embodiment 1.

[0083] For the specific structure of the inductor module, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plastic-encapsulated inductor module based on dual plating, characterized in that, It includes an inductor assembly (1), a molding compound (2), a power conductor (3), and a signal transmission conductor (4); the molding compound (2) is disposed on the outer peripheral surface of the inductor assembly (1); A metal plating layer (5) is provided on the surface of the power conductor (3); The signal transmission conductor (4) is disposed on the first surface of the encapsulation structure (2) in areas other than the exposed surface of the power conductor (3), and the structure of the signal transmission conductor (4) is configured according to the frequency of the signal to be transmitted. The first surface is the side surface on which the power conductor (3) is disposed.

2. The plastic-encapsulated inductor module based on dual plating as described in claim 1, characterized in that, The inductor assembly (1) includes a magnetic core (10) and a winding (11), wherein the winding (11) is disposed on the surface of the magnetic core (10); or, the winding (11) is wrapped by the magnetic core (10) and both ends of the winding (11) are exposed from the surface of the magnetic core (10); The encapsulation structure (2) is encapsulated on the outer peripheral surface of the magnetic core (10), and the two ends of the winding (11) are exposed from the first end face and the second end face of the encapsulation structure (2) to form electrical pads for connection with external circuits.

3. The plastic-encapsulated inductor module based on dual plating according to claim 2, characterized in that, The inner side of the encapsulation structure (2) is designed to be fully fitted with the outer peripheral surface of the magnetic core (10), or a heat dissipation gap of 0.1mm-0.3mm is reserved between the inner side of the encapsulation structure (2) and the outer peripheral surface of the magnetic core (10), and thermal grease or air is filled in the heat dissipation gap.

4. The plastic-encapsulated inductor module based on dual plating according to claim 2, characterized in that, The power conductor (3) is disposed on the outer peripheral surface of the magnetic core (10), and the top end, bottom end and the side near the outer side of the encapsulation structure (2) of the power conductor (3) are exposed; wherein, the exposed area accounts for 30%-50% of the surface area of ​​the power conductor (3).

5. The plastic-encapsulated inductor module based on dual plating according to claim 1, characterized in that, The metal coating (5) includes at least one metal layer, and each metal layer includes at least two segmented metal regions; The spacing between the segmented metal areas ranges from 0.1mm to 5mm; The thickness of each metal layer ranges from 0.1 μm to 1 μm; The horizontal offset between two adjacent segmented metal regions ranges from 0.2mm to 0.5mm, and the vertical offset ranges from 0.1mm to 0.3mm, in order to form a stable three-dimensional current channel and improve conductivity.

6. The plastic-encapsulated inductor module based on dual plating according to claim 1, characterized in that, When the frequency of the signal to be transmitted is less than or equal to 100MHz, the signal transmission conductor (4) is set to a planar plating layer with a thickness of 0.1μm-10μm and a signal trace width of 0.05mm-5mm. When the frequency of the signal to be transmitted is higher than 100MHz, the signal transmission conductor is formed by microstrip line structure or coplanar waveguide structure (4). When the frequency of the signal to be transmitted is higher than or equal to 1 GHz, the signal transmission conductor is formed by a stripline structure or a shielded microstrip line structure (4).

7. The plastic-encapsulated inductor module based on dual plating according to claim 1, characterized in that, The metal plating layer (5) includes a nickel plating layer, a gold plating layer and a passivation layer stacked together, wherein the nickel plating layer is disposed on the outer exposed surface of the power conductor (3).

8. The plastic-encapsulated inductor module based on dual plating according to claim 1, characterized in that, The minimum distance between the metal plating layer (5) and the signal transmission conductor (4) is greater than or equal to 0.5 mm; The metal plating (5) and the grounding terminal of the signal transmission conductor (4) are connected to improve signal integrity and anti-interference capability.

9. A method for fabricating a plastic-encapsulated inductor module based on a double-layer plating, characterized in that, For manufacturing a double-plated molded inductor module as described in any one of claims 1-8, comprising: The encapsulation structure (2) is disposed on the outer peripheral surface of the inductor assembly (1), the power conductor (3) is disposed on the first surface of the encapsulation structure (2), and a metal plating layer (5) is plated on the surface of the power conductor (3). Based on the frequency of the signal to be transmitted, the signal transmission conductor (4) is provided on the first surface of the encapsulated structure (2) in areas other than the exposed surface of the power conductor (3) to obtain the inductor module.

10. A power supply device, characterized in that, It includes at least one double-plated encapsulated inductor module as described in any one of claims 1-8.

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