Pouring type integrated transformer, inner matching assembly and preparation method of inner matching assembly

Abstract

The invention belongs to the technical field of radio frequency microwave functional components, and particularly relates to a pouring type integrated transformer, an internal matching component and a preparation method thereof, the pouring type integrated transformer comprises a microstrip impedance line of a multilayer spiral structure, a soft magnetic ferrite pouring body located outside the microstrip impedance line, and leading-out terminals arranged at the two ends of the microstrip impedance line; the micro-strip impedance line is arranged on a substrate with a certain dielectric constant requirement and forms a spiral structure along a set path, the micro-strip impedance line and the substrate of the micro-strip impedance line are coated with the soft magnetic ferrite pouring body, the soft magnetic ferrite pouring body is of an integrally formed structure, and the soft magnetic ferrite pouring body is obtained by mixing soft magnetic ferrite powder and a binder, pouring the mixture in a mold and carrying out curing demolding. Through the innovative structural design and preparation process, the technical bottlenecks of large size, low efficiency, inconsistency, difficulty in packaging and the like existing in a traditional manual winding matching mode are overcome, and a feasible technical scheme is provided for miniaturization, high performance and large-scale application of a power amplifier matching network in a radio frequency microwave system.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency microwave functional components, and in particular to a cast integrated transformer, an internal matching component and a preparation method thereof. Background Art

[0002] In the design of RF microwave systems, impedance matching technology plays a key role in achieving efficient energy transfer between different functional modules. In particular, the design of matching networks in components such as power amplifiers, couplers, filters, and antennas directly impacts the efficiency, bandwidth, and reliability of the entire system. Currently, the industry generally adopts 50 ohms as the standard impedance for RF interfaces. In the matching design of low-frequency power amplifier modules, a common method is to achieve impedance transformation and matching through transmission line transformers.

[0003] The existing technology generally adopts manual methods to prepare transmission line transformers. The method is to purchase specific cables with different impedance values, such as 12.5 ohms, 17.5 ohms, 25 ohms, 50 ohms, etc., and then manually wind them with ferrite cores to complete the production of the matching network. This method relies on multiple trial-and-error debugging, that is, by replacing cables with different impedances or adjusting the cable length, constantly disassembling and rewinding to achieve ideal matching performance. Although this method has a simple process, it has many problems such as low production efficiency, poor parameter consistency, complex debugging process, unsightly mechanical structure, and is not conducive to module packaging and product miniaturization. It seriously restricts the engineering and industrial development of low-frequency RF devices.

[0004] Traditional hand-wound transmission line transformers not only suffer from poor process repeatability but also suffer from significant errors in cable cutting length and winding accuracy, easily leading to poor matching and frequent rework. Furthermore, their exposed structure and bulky size hinder modular integration and aesthetic appeal, making them unsuitable for large-scale, miniaturized deployment in modern RF systems. With the advancement of communication technology and the increasing demands for system integration, traditional matching methods are increasingly exposed to limitations in practical applications. Summary of the Invention

[0005] To address these issues, the present invention proposes a cast-integrated transformer, internal matching assembly, and method for manufacturing the same. This solution integrates the transmission line, inductor structure, and magnetic material, employing a controllable mold structure and potting process to securely mold the transformer structure, avoiding the inconsistencies associated with traditional manual winding. This technology not only improves production efficiency and product consistency, but also achieves structural integration, aesthetics, and miniaturization, effectively supporting the development of high-reliability, low-cost, and automated production of low-frequency RF modules.

[0006] The present invention is achieved through the following technical solutions: A cast-type integrated transformer comprises: a microstrip impedance line with a multi-layer spiral structure, a soft ferrite cast body located outside the microstrip impedance line, and lead terminals arranged at both ends of the microstrip impedance line; The microstrip impedance line is arranged on a dielectric substrate and forms a spiral structure along a set path. The soft ferrite casting body covers the microstrip impedance line and the substrate. The soft ferrite casting body is an integrally formed structure, which is obtained by mixing soft ferrite powder and a binder, casting the mixture in a mold, and then demoulding the mixture after solidification.

[0007] Furthermore, the multilayer spiral microstrip impedance line is optimized within a preset frequency band by simulation software, and the optimization targets include dielectric parameters, device parameters, geometric parameters and electrical parameters.

[0008] Furthermore, the lead-out terminal includes an input end and an output end, which are respectively connected to the starting end and the ending end of the microstrip impedance line, and the lead-out terminal extends to the outer surface of the cast body.

[0009] A cast-integrated internal matching component comprises: a microstrip impedance line with a multi-layer spiral structure, a soft ferrite cast body located outside the microstrip impedance line, and a radio frequency chip embedded in the cast body; The soft ferrite casting body is an integral structure formed by mixing soft ferrite powder and a binder, casting and solidifying in a mold, and the entire structure covers the microstrip impedance line; A cavity for accommodating the radio frequency chip is provided inside the soft ferrite casting body. The radio frequency chip is connected to the microstrip impedance line via a lead, and the cavity is sealed with a packaging material.

[0010] Furthermore, the radio frequency chip includes a power amplifier chip or an MMIC chip, the lead is a gold wire bonding structure, and the cavity is arranged in the center or one end area of ​​the soft magnetic ferrite casting body.

[0011] A method for preparing a cast-type integrated transformer comprises the following steps: S1. Use simulation software to set microstrip impedance line structural parameters according to target impedance value and generate a graphic module; S2. processing a microstrip impedance line on a dielectric substrate according to the graphic module; S3, placing the microstrip impedance line into a mold and connecting the lead terminals; S4, mixing soft ferrite powder with a binder and pouring the mixture into a mold to cover the microstrip impedance line; S5. The mold is cured and demoulded to obtain a cast integrated transformer.

[0012] A method for preparing a cast-type integrated internal matching component comprises the following steps: S1. Use simulation software to set microstrip impedance line structural parameters according to target impedance value and generate a graphic module; S2. processing a microstrip impedance line on a dielectric substrate according to the graphic module; S3. Setting a reserved cavity in the mold for accommodating the radio frequency chip; S4, pouring the mixed soft ferrite powder and binder into the mold to form a coating structure and retain the cavity; S5. After curing and demoulding, embed the RF chip into the cavity and connect it to the microstrip impedance line through leads; S6. Seal the cavity with packaging material.

[0013] Preferably, the microstrip impedance line is optimized within a preset frequency band by simulation software, and the optimization targets include dielectric parameters, device parameters, geometric parameters and electrical parameters.

[0014] Beneficial effects of the invention: (1) The present invention adopts a casting process that integrates the cable and the magnetic core, replacing the traditional manual winding method, which greatly improves the consistency and efficiency of production and has significant engineering and industrialization advantages. Through mold forming and potting technology, it not only makes the product structure more stable and beautiful, but also achieves a high degree of integration of the cable, magnetic core, and chip, greatly saving space and significantly reducing the overall volume, meeting the needs of the miniaturization development of modern electronic equipment; (2) The present invention can flexibly select different transmission line impedance types as needed, providing a richer range of matching impedance characteristics, thereby achieving better matching effects over a wider frequency range and load conditions. This solution can effectively optimize key performance indicators such as efficiency, linearity, and bandwidth of the power amplifier module, further improving the stability and operating performance of the overall RF system; (3) The cast-in-place integrated structure of the present invention has higher mechanical strength and environmental adaptability, and can be used in application scenarios requiring high reliability and high consistency. At the same time, by integrating the matching network and the power amplifier chip inside the magnetic core, a chip + matching integrated package is achieved, which simplifies the system structure of the RF front end, reduces the complexity of design and debugging, and provides a new solution for the modularization and standardization of RF devices; (4) The present invention can be mass-produced and standardized, and its packaging form is similar to that of ordinary surface-mount components. It can be directly used in portable terminals such as mobile phones and watches, providing hardware support for their expansion of long-distance emergency communication functions. At the same time, the device is also suitable for ultra-long-distance communication, emergency rescue, large-scale deployment and other fields in low-altitude economic scenarios. It is particularly suitable for situations with high requirements on equipment size, weight, power consumption and other indicators, and has broad application prospects.

[0015] In summary, the present invention effectively overcomes the technical bottlenecks of traditional manual winding matching methods such as large size, low efficiency, inconsistency, and difficult packaging through innovative structural design and preparation process, and provides a practical new technical solution for the miniaturization, high performance and large-scale application of power amplifier matching networks in RF microwave systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0017] Figure 1 This is a perspective schematic diagram of a cast-integrated transformer proposed by the present invention; Figure 2 This is a schematic diagram of the installation structure of a cast-integrated transformer proposed in the present invention; Figure 3 This is a schematic diagram of the connection structure of a cast-integrated transformer proposed in the present invention; Figure 4 A perspective schematic diagram of a cast-integrated internal matching component proposed by the present invention; Figure 5 This is a structural diagram of a cast-integrated internal matching component proposed by the present invention; In the figure, 1- input balun and transmission line transformer, 2- power amplifier module, 3- output balun and transmission line transformer, 4- input port, 5- output port, 6- power amplifier chip, 7- casing, 8- pins. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0019] Example 1 This embodiment provides a specific implementation of a cast-type integrated transformer.

[0020] refer to Figure 1-Figure 3 Based on the required operating frequency band and matching requirements of the RF system, the electrical performance parameters that the transmission line transformer must meet are determined, including the operating frequency range, transmission loss, required inductance, coupling structure, etc. In this embodiment, the design frequency range is 1MHz–500MHz, and the operating frequency simulation is set to 10GHz, which serves as a reference point for the high-frequency behavior of the electrical performance of the matching line structure. To perform high-precision impedance simulation, electromagnetic simulation software is used to model and analyze the microstrip transmission line structure. The main material parameters used in the simulation modeling are as follows: Dielectric layer relative permittivity (Er): 9.6; relative magnetic permeability (Mur): 820; dielectric layer thickness (H): 10.0 mil; copper conductor thickness (T): 0.15 mil; metal conductivity (Cond): 4.1×10 7 S / m; shielding layer height (Hu): 3.9×10³ 4 mil (set to a maximum value to ignore its effect in the simulation); transmission line width (W): 25.0 mil; transmission line length (L): 100.0 mil.

[0021] Entering the above parameters into the simulation software yields the transmission line structure's characteristic impedance, Z0, of 47.25 ohms and equivalent electrical length, E_Eff, of 230 degrees. It's important to understand that this characteristic impedance isn't artificially set; it's a natural result of the combination of selected materials and structural dimensions. By adjusting the ratio of W and H, a close match to the target impedance can be achieved. Further structural adjustments can be made during the design process to meet varying matching requirements.

[0022] After confirming that the transmission line impedance characteristics meet the system requirements, the second step is to conduct a comprehensive simulation of the electromagnetic behavior of the structure after embedding the magnetic material, including key parameters such as equivalent inductance, coupling strength, leakage inductance, parasitic capacitance, and electromagnetic field distribution. The spatial distribution of magnetic flux density (B) is also evaluated. The following is some simulated magnetic flux density data (unit: Tesla): B = [2.0000, 1.8571, 1.7143, 1.5714, 1.4286, 1.2857, 1.1429, 1.0000,0.8571, 0.7143, 0.5714, 0.4286, 0.2857, 0.1429, 0.0000].

[0023] The data shows that the magnetic field is continuously distributed within the structure, with no apparent saturation or sudden changes. This indicates that the selected magnetic material is well matched to the coil structure and provides stable flux control capabilities. After completing simulation verification, the impedance line is fabricated using a 2D CAD drawing of the structure and process parameter files derived from the simulation results. This fabrication method utilizes precision circuit etching or laser cutting to create the desired conductor geometry by machining the transmission line pattern on a ceramic substrate. After fabrication, the transmission line is subjected to impedance testing and dimensional verification to ensure that the simulated values ​​align with the actual fabricated values.

[0024] This embodiment also includes casting molding of soft ferrite powder, and the specific method is as follows: Place the processed transmission line structure into the pre-designed mold cavity; In a vacuum or reduced pressure environment, slowly pour soft ferrite powder; Use in-mold hot pressing to pre-press and solidify to eliminate bubbles and increase density; Applying heat curing treatment to enable the magnetic powder material to be stably formed and cover the conductor area; After cooling, the mold is demoulded to form a complete integrated structure.

[0025] In the completed structure, the magnetic core completely encapsulates the entire transmission line conductor, forming a highly magnetically dense coupling system that effectively controls magnetic leakage and parasitic effects. Furthermore, the structure integrates the functions of a transmission line transformer and a balun, enabling unbalanced-to-balanced signal conversion, further improving matching efficiency and system compatibility.

[0026] This cast-in-place transmission line transformer is suitable for matching various low- and medium-frequency RF modules, and offers significant advantages in applications requiring high volume and performance, such as handheld devices, portable communication terminals, and miniaturized radar systems. Measured data demonstrates that this structure offers excellent leakage inductance control and negligible parasitic coupling effects, fully meeting engineering application requirements.

[0027] In summary, this embodiment provides a solution for preparing a cast transmission line transformer with integrated structure, simulated and optimized parameters, and standardized manufacturing process, which provides an effective technical approach for the engineering application and miniaturization upgrade of traditional RF matching components.

[0028] Example 2 Based on Example 1, this embodiment proposes a specific implementation method of a cast-type integrated internal matching component.

[0029] refer to Figure 4-Figure 5This component builds on the cast-type transmission line transformer structure of Example 1 by further embedding the RF power amplifier chip within the soft ferrite cast layer. The chip, matching structure, and external circuitry are integrated into the package housing. This embodiment aims to ensure efficient RF signal matching while addressing the bulk and complex debugging issues of traditional discrete matching components. It is suitable for miniaturized communication devices and high-density RF modules.

[0030] The core structure of the internal matching component includes: the multi-layer spiral microstrip impedance line and the soft ferrite casting layer as described in Example 1, the casting layer has a cylindrical hole with a diameter of 2.1 mm reserved for embedding the RF power amplifier chip; The RF power amplifier chip is fixed to the bottom of the hole with conductive silver glue, and the chip electrode is aligned with the end of the microstrip line; Gold wire bonding wires are used to connect chip electrodes and microstrip lines using ball bonding technology, with a bonding arc height of ≤30 μm and a spacing of 100 μm.

[0031] The processing flow is as follows: Step 1: Transmission line processing and chip pre-assembly: A cast transmission line transformer is manufactured according to the process of Example 1. Conductive silver glue or eutectic is applied to the reserved holes of the soft ferrite casting layer, and the RF power amplifier chip is mounted. After curing, the excess glue is cleaned.

[0032] Step 2: Gold wire bonding: Use an automatic bonding machine (accuracy ±1 μm) to complete the gold wire bonding between the chip electrode and the microstrip line. The bonding parameters are: pressure 30 gf, temperature 150°C, and time 200 ms.

[0033] Step 3: Inject low-viscosity epoxy resin from the potting hole, vacuum degassing and solidify to seal the cavity and form a sealed structure.

[0034] Step 4: Pin welding: pins are directly processed on the shell formed on the outer surface of the casting layer through a mold forming process.

[0035] The above shows and describes the basic principles and main features of the present utility model and the advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present utility model. Various changes and improvements are possible without departing from the spirit and scope of the present utility model. Such changes and improvements are within the scope of the present utility model. The scope of protection claimed in the present utility model is defined by the appended claims and their equivalents.

Claims

1. A cast-integrated transformer, characterized in that: include: A microstrip impedance line with a multi-layer spiral structure, a soft ferrite casting body located outside the microstrip impedance line, and lead terminals arranged at both ends of the microstrip impedance line; The microstrip impedance line is arranged on a dielectric substrate and forms a spiral structure along a set path. The soft ferrite casting body covers the microstrip impedance line and the substrate. The soft ferrite casting body is an integrally formed structure, which is obtained by mixing soft ferrite powder and a binder, casting the mixture in a mold, and then demoulding the mixture after solidification.

2. A cast-integrated transformer according to claim 1, characterized in that: The multilayer spiral microstrip impedance line is optimized within a preset frequency band by simulation software, and the optimization targets include dielectric parameters, device parameters, geometric parameters and electrical parameters.

3. The cast-in-place integrated transformer according to claim 1, characterized in that: The lead-out terminal comprises an input end and an output end, which are respectively connected to the starting end and the ending end of the microstrip impedance line, and the lead-out terminal extends to the outer surface of the cast body.

4. A cast-integrated internal matching component, characterized in that: include: A microstrip impedance line with a multi-layer spiral structure, a soft ferrite casting body located outside the microstrip impedance line, and a radio frequency chip embedded in the casting body; The soft ferrite casting body is an integral structure formed by mixing soft ferrite powder and a binder, casting and solidifying in a mold, and the entire structure covers the microstrip impedance line; A cavity for accommodating the radio frequency chip is provided inside the soft ferrite casting body. The radio frequency chip is connected to the microstrip impedance line via a lead, and the cavity is sealed with a packaging material.

5. The cast-integrated internal matching component according to claim 4, characterized in that: The radio frequency chip includes a power amplifier chip or an MMIC chip, the lead is a gold wire bonding structure, and the cavity is arranged in the center or one end area of ​​the soft magnetic ferrite casting body.

6. A method for preparing a cast-type integrated transformer, characterized in that: The following steps are involved: S1. Use simulation software to set microstrip impedance line structural parameters according to target impedance value and generate a graphic module; S2. processing a microstrip impedance line on a dielectric substrate according to the graphic module; S3, placing the microstrip impedance line into a mold and connecting the lead terminals; S4, mixing soft ferrite powder with a binder and pouring the mixture into a mold to cover the microstrip impedance line; S5. The mold is cured and demoulded to obtain a cast integrated transformer.

7. A method for preparing a cast-integrated internal matching component, characterized in that: The following steps are involved: S1. Use simulation software to set microstrip impedance line structural parameters according to target impedance value and generate a graphic module; S2. processing a microstrip impedance line on a dielectric substrate according to the graphic module; S3. Setting a reserved cavity in the mold for accommodating the radio frequency chip; S4, pouring the mixed soft ferrite powder and binder into the mold to form a coating structure and retain the cavity; S5. After curing and demoulding, embed the RF chip into the cavity and connect it to the microstrip impedance line through leads; S6. Seal the cavity with packaging material.

8. The preparation method according to claim 6 or 7, characterized in that The microstrip impedance line is optimized within a preset frequency band by simulation software, and the optimization targets include dielectric parameters, device parameters, geometric parameters and electrical parameters.

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