A thick and thin film double cap resistor assembly and double cap resistor body capable of avoiding weld point fracture

Abstract

The application discloses a thick-thin film double-cap resistor assembly capable of avoiding welding point fracture and a double-cap resistor body, and relates to the technical field of electronic components, which comprises a thick-film resistor body and a thin-film resistor body, both of which form a composite and are arranged on the top layer of the whole module; the flexible metal transition layer adopts a serpentine metal foil structure, which can effectively absorb and release the stress generated between the ceramic substrate and the metal cap due to the mismatch of the thermal expansion coefficients in the heat cycle process through elastic deformation. Secondly, through the synergistic effect of the tree-shaped fractal micro-channel and the functional gradient capillary core, the phase change working medium is utilized in combination with the magnetic fluid working medium and the external magnetic field, so that the active thermal management of on-demand distribution is realized, and the generation of thermal stress is reduced from the source. The whole body realizes the synergistic mechanism of stress buffering, efficient heat dissipation and intelligent monitoring, which not only completely solves the problem of welding point fracture, but also significantly improves the power density, service life, safety and reliability of the resistor under different working conditions.

Description

Technical Field

[0001] This invention relates to the field of electronic components technology, specifically to a thick-film double-cap resistor assembly and a double-cap resistor body that can prevent solder joint breakage. Background Technology

[0002] Resistive components, especially high-power thick-film resistors, thin-film resistors, or their composite structures, are fundamental components in modern electronic circuits and are widely used in industrial control, new energy, communication base stations, and automotive electronics. These resistors typically involve fabricating the resistive element on a ceramic substrate and then electrically connecting and mechanically encapsulating it with a metal cap and external leads to achieve high current carrying capacity and ease of installation.

[0003] Currently, a common and serious reliability problem exists in resistor components during long-term operation, especially when subjected to frequent power cycles and temperature changes: fatigue fracture at the solder joints. Existing technological improvements cannot meet the stringent reliability requirements (e.g., lifespan exceeding 100,000 hours and failure rate below 1 FIT) of resistor components in fields such as aerospace, deep space exploration, high-reliability military electronics, backbone network communication equipment, and implantable high-end medical instruments. Because resistor components are typically composed of multiple materials, the coefficient of thermal expansion of the ceramic substrate (such as alumina or aluminum nitride) differs significantly from that of the metal cap and external copper leads soldered onto it. This causes drastic temperature fluctuations when the resistor is switched on and off or when power changes, resulting in varying degrees of expansion and contraction of different materials. Consequently, enormous cyclic shear stress is generated at the solder joints between the ceramic substrate and the metal components. This cyclic thermal stress cannot be effectively absorbed or released and must be borne by the solder joints themselves. After dozens or even hundreds of thermal cycles, fatigue microcracks will initiate inside the solder joints. These microcracks will continue to expand and connect over time, eventually leading to failure or complete breakage of the electrical connection of the solder joint. Therefore, it is necessary to propose a thick film double-cap resistor assembly and double-cap resistor body that can avoid solder joint breakage. Summary of the Invention

[0004] The purpose of this invention is to provide a thick-film double-cap resistor assembly and a double-cap resistor body that can avoid solder joint breakage, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a thick-film double-cap resistor assembly that can prevent solder joint breakage, comprising: Thick film resistors and thin film resistors are combined and installed on the top layer of the entire module. A high thermal conductivity aluminum nitride ceramic substrate assembly is installed at the bottom of a thick film resistor and a thin film resistor. The high thermal conductivity aluminum nitride ceramic substrate assembly includes a ceramic substrate, a thin film resistor region, a thick film resistor region, and an isolation groove. The thin film resistor region is first fabricated on the ceramic substrate, and then the thick film resistor region is fabricated by laser windowing process. The thick film resistor region and the thin film resistor region are electrically isolated by the laser-etched isolation groove, and the required electrical interconnection is achieved at specific points through the metal connecting pads on both sides of the thick film resistor and the thin film resistor. A flexible metal transition layer is located between the two ends of the ceramic substrate and the metal caps connected to the side ends of the metal connecting disk. The flexible metal transition layer is a serpentine metal foil, one end of which is connected to the end electrode on the ceramic substrate by high-temperature brazing, and the other end is welded to the external lead wire. The microchannel phase change heat sink assembly is tightly attached to the entire bottom of a ceramic substrate. The microchannel phase change heat sink assembly includes a whole plate, which is an independent copper or silicon plate. The interior of the whole plate is formed with dendritic fractal microchannels by etching or processing. The dendritic fractal microchannels are filled with a phase change working fluid. Furthermore, the microchannels are more densely packed below the thick film resistor region, forming a capillary pump structure. The microchannel phase change heat sink assembly is tightly bonded to the bottom of the ceramic substrate by a high thermal conductivity silicone grease or thermal adhesive, and is electrically isolated from the thick film resistor and thin film resistor.

[0006] Preferably, the capillary pump structure in the microfluidic phase change heat sink assembly is a functionally graded capillary core, whose capillary pore size or surface energy exhibits a gradient change along the direction from the thick film resistive region to the thin film resistive region, so as to generate a stronger directional capillary driving force.

[0007] Preferably, the phase change working medium filled in the tree-like fractal microchannel is a magnetohydrodynamic phase change working medium, and a resistor protection shell is provided on the outside of the ceramic substrate. The resistor protection shell is symmetrically equipped with miniature external magnetic field generators for driving the flow of the magnetohydrodynamic phase change working medium at both ends along its own central axis.

[0008] Preferably, a miniature metal strain gauge is installed in the deformation area of ​​the metal foil of the flexible metal transition layer. The miniature metal strain gauge has an independent signal output terminal for connecting to an external monitoring circuit to realize real-time monitoring of the mechanical stress and temperature of the thick film resistor and the thin film resistor.

[0009] Preferably, the side end of the isolation groove is connected to an isolation groove support rib, the isolation groove support rib is integrally formed with the ceramic substrate, and the side end of the isolation groove support rib is provided with a wire groove.

[0010] Preferably, the side end of the metal connecting plate is connected to a metal cap electrical connection part, and the metal cap electrical connection part and the metal cap are integrally formed.

[0011] Preferably, solder joints are symmetrically installed on both sides of the side end of the entire board along its central axis, and stress monitoring end and temperature monitoring end are respectively connected to the side end of the solder joint.

[0012] Preferably, the interior of the tree-like fractal microchannel is provided with phase change working fluid reservoirs at unequal intervals. The phase change working fluid reservoirs are used to store and stably supply the phase change working fluid. The phase change working fluid reservoirs are in full communication with the microchannel. The side end of the capillary pump structure is provided with a microchannel working fluid outlet and a monitoring interface. The microchannel working fluid outlet and monitoring interface serve as circulation channels for the phase change working fluid.

[0013] Preferably, a heat shrink tubing is installed on the top of the resistor protection housing, and a tab is connected to the top of the heat shrink tubing. The interior of the resistor protection housing is filled with an elastic thermally conductive buffer medium, which completely covers the internal resistor structure, the metal cap, and the connection part of the lead wire.

[0014] A double-cap resistor includes a double-cap resistor, wherein the double-cap resistor is a combination of a thick-film composite resistor and a flexible metal transition layer.

[0015] Compared with the prior art, the beneficial effects of the present invention are: In this invention, by employing a serpentine metal foil structure in the flexible metal transition layer, the stress generated by the mismatch in thermal expansion coefficients between the ceramic substrate and the metal cap can be effectively absorbed and released during thermal cycling through its own elastic deformation. This mechanically cuts off the path of stress transmission to the solder joint, achieving fundamental stress buffering. Secondly, the microfluidic phase change heat sink component utilizes the synergistic effect of the tree-like fractal microchannels and functionally graded capillary cores to efficiently absorb heat through the liquid-gas phase change of the phase change working fluid. Combined with the intelligent interaction between the magnetohydrodynamic working fluid and the external magnetic field, it achieves on-demand active thermal management, reducing the generation of thermal stress at its source. Furthermore, the integrated intelligent monitoring system, by setting strain gauges in the flexible transition layer and multi-parameter monitoring interfaces in the microchannels, achieves real-time in-situ sensing of the mechanical stress, temperature, and heat dissipation status of the resistive element. Through closed-loop linkage with an external controller, the operating state can be dynamically adjusted, achieving a leap from passive failure to proactive early warning. Simultaneously, the integrated internal structure enhances the overall mechanical strength, the elastic thermally conductive encapsulation material provides triple protection, and the self-healing microcapsule design adds redundancy to long-term reliability. Through a synergistic mechanism of stress buffering, efficient heat dissipation, and intelligent monitoring, the overall system not only completely solves the problem of solder joint fracture, but also significantly improves the power density, service life, and safety and reliability of the resistor under different operating conditions. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the main structure of a thick-film double-cap resistor assembly that can avoid solder joint breakage according to the present invention. Figure 2 This is a schematic diagram of the internal structure of the resistor protection shell in a thick-film double-cap resistor assembly that can prevent solder joint breakage according to the present invention. Figure 3 This is a schematic diagram of the separation structure of the main body in a thick-film double-cap resistor assembly that can avoid solder joint breakage according to the present invention. Figure 4 This is a schematic diagram of the microchannel phase change heat sink component in a thick-film double-cap resistor assembly that can avoid solder joint breakage according to the present invention.

[0017] In the diagram: 100, Resistor protection housing; 200, Heat shrink tubing; 300, Insert; 400, Metal cap; 500, Insulating fixing plate; 600, Miniature external magnetic field generator; 700, Electrical connection part of metal cap; 800, Metal connecting plate; 900, High thermal conductivity aluminum nitride ceramic substrate assembly; 901, Ceramic substrate; 902, Isolation groove; 903, Isolation groove support rib; 904, Wire groove; 110, Thick film resistor; 120, Thin film resistor; 130, Microchannel phase change heat sink assembly; 131, Whole board; 132, Solder joint; 133, Stress monitoring end; 134, Temperature monitoring end; 135, Tree-like fractal microchannel; 136, Phase change working fluid reservoir; 137, Microchannel working fluid outlet; 140, Flexible metal transition layer. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In this invention, to solve the problem of thermal stress caused by mismatched coefficients of thermal expansion in the prior art, thereby completely resolving the issue of solder joint fatigue fracture, this invention provides a thick-film double-cap resistor assembly that can prevent solder joint fracture, as described above. Figures 1-4 As shown: including: Thick-film resistor 110 and thin-film resistor 120, forming a composite, are mounted on the top layer of the entire module. A high thermal conductivity aluminum nitride ceramic substrate assembly 900 is mounted at the bottom of the thick-film resistor 110 and thin-film resistor 120. The high thermal conductivity aluminum nitride ceramic substrate assembly 900 includes a ceramic substrate 901, a thin-film resistor region, a thick-film resistor region, and an isolation groove 902. The thin-film resistor region is first fabricated on the ceramic substrate 901, and then the thick-film resistor region is fabricated using a laser windowing process. The thick-film resistor region and the thin-film resistor region are electrically isolated by the laser-etched isolation groove 902, and the required electrical interconnection is achieved at specific points through metal connecting pads 800 on both sides of the thick-film resistor 110 and the thin-film resistor 120. A flexible metal transition layer 140 is located at both ends of the ceramic substrate 901 and the sides of the metal connecting pads 800. Between the connected metal caps 400, the flexible metal transition layer 140 is a serpentine metal foil, one end of which is connected to the end electrode on the ceramic substrate 901 by high-temperature brazing, and the other end is welded to the external lead wire; the microfluidic phase change heat sink assembly 130 is tightly attached to the entire bottom of the ceramic substrate 901. The microfluidic phase change heat sink assembly 130 includes a whole plate 131, which is an independent copper or silicon plate. The interior of the whole plate is formed with dendritic fractal microchannels 135 by etching or processing. The dendritic fractal microchannels 135 are filled with phase change working fluid. Furthermore, the microchannels are more densely packed below the thick film resistor region, forming a capillary pump structure; the microfluidic phase change heat sink assembly 130 is tightly attached to the bottom of the ceramic substrate 901 by high thermal conductivity thermal grease or thermal adhesive, and is electrically isolated from the thick film resistor 110 and the thin film resistor 120. The capillary pump structure in the microfluidic phase change heat sink assembly 130 is a functionally graded capillary core (e.g., the capillary pore size is 5-20 μm below the thick film resistive region, gradually increasing to 50-100 μm towards the edge region). Its capillary pore size or surface energy exhibits a gradient change along the direction from the thick film resistive region to the thin film resistive region, so as to generate a stronger directional capillary driving force. The phase change working medium filled in the dendritic fractal microfluidic channel 135 is a magnetohydrodynamic phase change working medium. A resistor protection shell 100 is provided on the outside of the ceramic substrate 901. The resistor protection shell 100 is symmetrically equipped with miniature external magnetic field generators 600 for driving the flow of the magnetohydrodynamic phase change working medium at both ends along its own central axis. Solder joints 132 are symmetrically mounted on both sides of the side of the board 131 along its central axis. The sides of the solder joints 132 are respectively connected to stress monitoring terminals 133 (specifically, signal output interfaces of miniature pressure sensors). When the resistor component generates thermal stress due to power cycling or changes in the external environment, this stress is transmitted through the ceramic substrate 901 to the microchannel heat sink component, causing changes in the mechanical pressure borne by its interior, especially the sealed microchannel cavity and the solder joints 132. Then, the integrated miniature pressure sensor will sense this minute pressure change in real time and convert it into an electrical signal. After that, the electrical signal is transmitted to the external physical interface, stress monitoring terminal 133, through built-in wires.Finally, an external PLC controller can connect to this interface to read the structural stress data inside the resistor in real time. Once the stress value approaches the design threshold, the system can issue an early warning, indicating a potential risk of overload or welding fatigue. The temperature monitoring port 134 (specifically, the signal output interface of a miniature temperature sensor) is also connected. The heat generated by the resistor during operation is conducted to the microchannel heat sink component, and the temperature in this area changes in real time. The integrated miniature temperature sensor then detects this temperature change and generates a corresponding change in resistance or voltage. This electrical signal representing the temperature is then transmitted to the external physical interface, temperature monitoring port 134. Finally, by monitoring the signal at this port, the real-time temperature of the hottest area of ​​the resistor can be accurately obtained. This system not only prevents the resistor from being damaged by overheating but also indirectly evaluates the efficiency of the phase change cooling system through temperature data (for example, an abnormally high temperature may indicate poor phase change circulation or insufficient working fluid). The dendritic fractal microchannel 135 contains phase change working fluid reservoirs 136 spaced at unequal intervals. These reservoirs store and stably supply the phase change working fluid. The reservoirs 136 are fully connected to the dendritic fractal microchannel 135, ensuring sufficient replenishment of the working fluid during phase changes (e.g., from liquid to gas), preventing working fluid shortages from affecting heat dissipation efficiency. Furthermore, through its own elasticity or volume changes, the capillary pump structure enhances the directional flow driving force of the working fluid, ensuring continuous and stable phase change heat dissipation. The structure is equipped with a microfluidic working fluid outlet 137 and a monitoring interface on its side. The microfluidic working fluid outlet 137 and monitoring interface serve two purposes: firstly, as a circulation channel for the phase change working fluid, enabling directional discharge and replenishment of the working fluid within the microfluidic channel to ensure the continuity of the phase change heat dissipation cycle; and secondly, as a status monitoring interface, connecting sensors such as temperature and flow rate to collect parameters such as the phase change state and flow rate of the working fluid within the microfluidic channel in real time. The feedback data allows for precise evaluation of the heat dissipation effect of the microfluidic phase change heat sink component 130, providing a basis for optimizing the overall resistor structure. The high thermal conductivity aluminum nitride ceramic substrate component 900 is the support and circuit foundation of the entire resistor. Firstly, a high-precision, low-temperature-coefficient thin-film resistor 120 is fabricated on the high thermal conductivity aluminum nitride ceramic substrate 901 using precision processes such as sputtering and photolithography, forming the fine adjustment part of the circuit. Next, a window is created in a predetermined area using laser, and a thick-film resistor 110 capable of carrying high power is formed using screen printing and high-temperature sintering processes. Subsequently, a laser is used to etch precise isolation grooves 902 between the thick film resistor region and the thin film resistor region to achieve electrical isolation between the two. The required electrical interconnection is then achieved at specific points by metal connecting disks 800 made on both sides of the resistor body, thereby forming a composite resistor body with complementary performance.The microfluidic phase change heat sink component 130 is designed to address the issue of solder joint fatigue fracture caused by mismatched thermal expansion coefficients. First, when the thick-film resistor 110 and thin-film resistor 120 generate significant heat due to energization, this heat is rapidly conducted downwards through the high thermal conductivity aluminum nitride ceramic substrate 901 and into the microfluidic phase change heat sink component 130, which is tightly bonded to the bottom of the substrate. Next, the heat is absorbed by the phase change working fluid filled within the dendritic fractal microchannels 35. After absorbing heat, the working fluid undergoes a liquid-gas phase change, a process that absorbs a substantial amount of heat, achieving efficient heat dissipation. Then, the capillary pump structure directly below the thick-film resistor region begins to function. This capillary pump structure is a functionally graded capillary core, where the capillary pore size or surface energy varies gradient from the center of the heat source to the edge, generating a strong directional capillary force. This force pushes the gaseous working fluid towards the condensation zone and simultaneously pulls the condensed, liquid-like working fluid back to the center of the heat source, forming a continuous cycle that requires no external power. To further enhance heat dissipation controllability, a magnetohydrodynamic (MHD) phase change medium (various magnetic nanoparticles with different Curie temperatures) is used. The liquid phase change medium is preferably a low-boiling-point, highly insulating, and chemically stable fluorinated carbon compound (such as FC-72 or HFE-7100) or deionized water. Its core function is to absorb heat generated by resistance and then undergo a liquid-gas phase change, utilizing the latent heat of phase change to absorb a large amount of heat. In the liquid carrier, specially modified magnetic nanoparticles are uniformly and stably suspended. These particles are typically ferrites, cobalt ferrites, or specific alloys, with particle sizes controlled between 10-30 nanometers to ensure superparamagnetism and prevent permanent aggregation in the absence of a magnetic field. When all magnetic particles retain their magnetism, the entire MHD working fluid exhibits a strong response to the magnetic field generated by the micro external magnetic field generator 600. The magnetic field can effectively guide, agitate, or pump the entire fluid, significantly improving the fluid circulation speed and heat exchange efficiency, especially during startup or when enhanced heat transfer is required. Specifically, (e.g., multiple magnetic nanoparticles with different Curie temperatures, including those with lower and higher Curie temperatures respectively). When the resistor locally overheats, causing the working fluid temperature in that area to exceed that of the magnetic nanoparticles with the lower Curie temperature but remain below that of the magnetic nanoparticles with the higher Curie temperature, the nanoparticles with the lower Curie temperature lose their magnetism, while the other type retains its magnetism. This leads to a significant decrease in the overall magnetization of the overheated area. At this point, the external magnetic field's gripping or pulling force on the overheated area weakens, causing the magnetic field force generated by the micro external magnetic field generator 600 to preferentially act on the area with lower temperature and stronger magnetism. This automatically drives more cooled liquid working fluid to the overheated area for remediation, achieving intelligent heat dissipation on demand. This avoids the ineffective consumption of magnetic field energy in the already overheated gas phase area where heat dissipation efficiency may decrease. If the temperature continues to rise, exceeding the Curie temperature of all particles, the direct driving effect of the magnetic field on the working fluid disappears, and the overall heat dissipation mode relying on the capillary pump structure is retained.Although this results in a performance degradation, it ensures basic safe operation under extreme conditions. Miniature external magnetic field generators 600, located at both ends of the resistor-protected housing 100, can drive the directional flow or disturbance of the magnetohydrodynamic working fluid, thereby dynamically enhancing heat exchange efficiency under extreme conditions. Furthermore, the unequally spaced phase change working fluid reservoirs 136 within the microchannels act as reservoirs and pressure buffers. This allows the phase change working fluid reservoirs 136 to replenish the liquid working fluid consumed by the phase change in a timely manner, preventing drying out, and can maintain pressure balance within the channel through their own elastic deformation, ensuring stable circulation. The flexible metal transition layer 140 acts as a single-stress buffer and provides reliable connection, further solving the problem of weld breakage. Firstly, the flexible metal transition layer 140 is a serpentine metal foil, one end of which is firmly connected to the end electrode on the ceramic substrate 901 via high-temperature brazing. Then, its other end is welded to the external leads and metal cap 400. When the entire system undergoes thermal cycling due to power changes, the mismatch in the thermal expansion coefficients of the ceramic and metal materials can generate stress. Subsequently, based on the resulting stress, the serpentine flexible metal transition layer 140 effectively absorbs and releases this thermal stress through its own elastic deformation, preventing stress concentration from being transmitted to the brittle ceramic ends or external solder joints, thereby fundamentally preventing solder joint fatigue fracture. Then, through the stress monitoring end 133 and temperature monitoring end 134 located on the side of the microfluidic phase change heat sink assembly 130, and the monitoring interface on the microfluidic working fluid outlet 137, the overall system can collect real-time data on the operating temperature of the thick film resistor 110 and the thin film resistor 120, the solder joint stress state, and the phase change efficiency and flow rate of the working fluid. This real-time data is then fed back to an external PLC controller. The PLC controller can then dynamically adjust the load power of the resistor or control the intensity of the miniature external magnetic field generator 600, thus forming an intelligent closed loop of monitoring, feedback, and simultaneous adjustment, ensuring that the resistor always operates in the optimal and safest state.

[0020] More specifically, according to Figures 1-3As shown, a miniature metal strain gauge is installed in the deformation area of ​​the metal foil of the flexible metal transition layer 140. The miniature metal strain gauge has an independent signal lead-out terminal for connection to an external monitoring circuit to realize real-time monitoring of the mechanical stress and temperature of the thick film resistor 110 and the thin film resistor 120. An isolation groove support rib 903 is connected to the side end of the isolation groove 902. The isolation groove support rib 903 and the ceramic substrate 901 are integrally formed. A wire groove 904 is opened on the side end of the isolation groove support rib 903. A metal cap electrical connection part 700 is connected to the side end of the metal connecting plate 800. The metal cap electrical connection part 700 and the metal cap 400 are integrally formed. A heat shrink tubing 200 is installed on the top of the resistor protection housing 100. An insert 300 is connected to the top of the heat shrink tubing 200. The interior of the resistor protection housing 100 is filled with an elastic thermally conductive buffer medium, which completely covers the internal resistor structure, the metal cap, and the connection part of the lead wire. On a high thermal conductivity aluminum nitride ceramic substrate 901, a high-precision, low-temperature-coefficient thin-film resistor 120 is fabricated using precision processes such as sputtering and photolithography, forming the fine adjustment part of the circuit. Next, a window is created in a predetermined area using a laser, followed by screen printing and high-temperature sintering to form a high-power thick-film resistor 110. Then, a precise isolation groove 902 is etched between the thick-film resistor region and the thin-film resistor region using a laser, achieving electrical isolation between them. An isolation groove support rib 903 is connected to the side end of the isolation groove 902. This support rib is integrally formed with the ceramic substrate 901, effectively enhancing the structural strength of the isolation groove 902 and preventing micro-cracks caused by stress during subsequent processes and use. A wire groove 904 is formed on the side end of the isolation groove support rib 903, providing a regular routing path for the internal electrical connection wires. Finally, the required electrical interconnection is achieved at specific points using metal connecting pads 800 fabricated on both sides of the resistor, thus forming a composite resistor with complementary performance. The side end of the metal connecting plate 800 is connected to a metal cap electrical connection part 700, which is integrally formed with the metal cap 400, ensuring the integrity and mechanical strength of the electrical connection path from the resistor to the external package. The flexible metal transition layer 140 is a serpentine metal foil, one end of which is firmly connected to the end electrode on the ceramic substrate 901 via high-temperature brazing. Then, its other end is welded to the external leads and the metal cap 400. When the component undergoes thermal cycling due to power changes, the mismatch in the thermal expansion coefficients of materials such as ceramics and metals can generate stress. Subsequently, the serpentine flexible metal transition layer effectively absorbs and releases these thermal stresses through its own elastic deformation, avoiding stress concentration transmission to the brittle ceramic end or external solder joints, thereby fundamentally preventing solder joint fatigue fracture. Furthermore, a miniature metal strain gauge is installed in the metal foil deformation area of ​​the flexible metal transition layer 140. This strain gauge has an independent signal output terminal for connection to an external monitoring circuit.It can sense and measure the deformation of the transition layer itself in real time. This deformation directly reflects the magnitude of the mechanical stress acting on the resistor and the change in ambient temperature, thereby achieving real-time, in-situ monitoring of the mechanical stress and temperature borne by the thick film resistor 110 and the thin film resistor 120. Simultaneously, the interior of the resistor protection housing 100 is filled with an elastic thermally conductive buffer medium. This medium completely covers the internal composite resistor structure, the metal cap 400, and the lead wire connection, serving a triple function: firstly, further buffering external mechanical vibration and internal stress; secondly, acting as an auxiliary heat conduction path to dissipate heat more evenly; and thirdly, providing electrical insulation to enhance reliability. A heat shrink tubing 200 is installed on the top of the resistor protection housing 100, and a plug 300 for external circuit connection is connected to the top of the heat shrink tubing 200, forming a complete and stable external interface. Furthermore, insulating fixing plates 500 are installed on both end surfaces of the resistor protection housing 100 to fix the mounting nodes of the miniature external magnetic field generator 600.

[0021] Preferably, the present invention also has another technical solution, a double-cap resistor, including a thick film double-cap resistor assembly that can prevent solder joint breakage.

[0022] It should be noted that the dendritic fractal microchannel 135 in the microfluidic phase change heat sink component 130 contains a large number of microcapsules. The microcapsules are filled with a flowable insulating repair material. When cracks appear on the wall of the dendritic fractal microchannel 135, the microcapsules rupture and release the repair material, achieving self-healing sealing. (That is, when the resistor generates microcracks due to extreme stress and extends to the wall of the dendritic fractal microchannel 135, it will crush the microcapsules inside the dendritic fractal microchannel 135. The repair liquid and curing agent flow out simultaneously, mix at the crack, undergo a chemical reaction, and quickly solidify into a high-strength insulating seal, automatically sealing the crack and preventing coolant leakage and electrical short circuits.) When local stress concentration, such as crack propagation, reaches a threshold, it can preferentially rupture at the crack tip. When the crack causes two adjacent microcapsules to rupture simultaneously, the outflowing monomers can be adsorbed and retained in the crack under the capillary action of the crack, and quickly undergo a cross-linking reaction to form a strong polymer seal.

[0023] Furthermore, the present invention also provides a method for manufacturing a thick-film double-cap resistor assembly that can avoid solder joint breakage, comprising the following steps: S1. On a high thermal conductivity aluminum nitride ceramic substrate 901, a thin film resistor 120 is fabricated by sputtering and photolithography. A window is opened in a predetermined area by laser, and a thick film resistor 110 is formed by screen printing and high-temperature sintering. Then, an isolation groove 902 is etched between the thick film and the thin film resistor area by laser to achieve electrical isolation. Next, metal connecting pads 800 are fabricated on both sides of the thick film resistor 110 and the thin film resistor 120 to achieve electrical interconnection between the thick film resistor 110 and the thin film resistor 120.

[0024] S2. A tree-like fractal microchannel 135 is formed on an independent plate by etching or processing. A functionally graded capillary core is constructed in the microchannel directly below the thick film resistor region. A magnetofluid phase change working fluid is filled into the tree-like fractal microchannel 135, so that the microchannel phase change heat sink assembly 130 can be tightly attached to the bottom of the ceramic substrate 901 through a high thermal conductivity interface material.

[0025] S3. One end of the flexible metal transition layer 140 made of serpentine metal foil is connected to the end electrode of the ceramic substrate 901 by high-temperature brazing. A micro metal strain gauge is installed in the deformation area of ​​the flexible metal transition layer 140. The other end of the flexible metal transition layer 140 is welded to the external lead and metal cap 400.

[0026] S4. Fill the inside of the resistor protection housing 100 with an elastic thermally conductive buffer medium, place the assembled resistor structure inside the resistor protection housing 100 so that the buffer medium completely covers the internal structure, and install the heat shrink tubing 200 and insert 300 to form a complete external interface. Install and fix the miniature external magnetic field generator 600 on both sides of the resistor protection housing 100 through the insulating fixing plate 500 to ensure the stable operation of the miniature external magnetic field generator 600.

[0027] S5. Connect the stress monitoring terminal 133 and the temperature monitoring terminal 134 to the external monitoring circuit, connect the monitoring interface of the microfluidic working fluid outlet 137 to the sensor system, establish signal connection between all monitoring terminals and the external PLC controller, and form a closed-loop control system.

[0028] S6. Then, power on the device to test the electrical performance of the overall composite resistor, verify the heat dissipation effect of the microchannel phase change heat sink component 130, calibrate the measurement accuracy of the stress and temperature monitoring structure, and test the response performance of the intelligent closed-loop control system.

[0029] It should be noted that the basic form of this invention (i.e., the microfluidic phase change heat sink assembly 130 and the flexible metal transition layer 140) can significantly improve the resistance to solder joint breakage. Based on this, one or more functional modules can be selectively integrated according to different reliability levels and budgets. For example, using a magnetohydrodynamic working fluid and an external magnetic field for coordinated control on the heat dissipation module; adding sensors such as micro-metal strain gauges; or adding microcapsule self-healing mechanisms. This allows the invention to meet the cost control requirements of ordinary industrial applications while also satisfying the extreme performance demands of extreme applications through functional stacking.

[0030] The wiring diagrams of the stress monitoring terminal 133 and the temperature monitoring terminal 134 in this invention are common knowledge in the field, and their working principle is a well-known technology. The appropriate model is selected according to the actual use. Therefore, the control method and wiring arrangement of the stress monitoring terminal 133 and the temperature monitoring terminal 134 will not be explained in detail.

[0031] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thick-film double-cap resistor assembly that can prevent solder joint breakage, characterized in that, include: A thick film resistor (110) and a thin film resistor (120) are combined and installed on the top layer of the entire module. A high thermal conductivity aluminum nitride ceramic substrate assembly (900) is installed at the bottom of a thick film resistor (110) and a thin film resistor (120). The high thermal conductivity aluminum nitride ceramic substrate assembly (900) includes a ceramic substrate (901), a thin film resistor region, a thick film resistor region, and an isolation groove (902). The thin film resistor region is first fabricated on the ceramic substrate (901), and then the thick film resistor region is fabricated by a laser windowing process. The thick film resistor region and the thin film resistor region are electrically isolated by the isolation groove (902) etched by the laser. The required electrical interconnection is achieved at a specific point by the metal connecting disks (800) on both sides of the thick film resistor (110) and the thin film resistor (120). A flexible metal transition layer (140) is located between the two ends of the ceramic substrate (901) and the metal cap (400) connected to the side end of the metal connecting disk (800). The flexible metal transition layer (140) is a serpentine metal foil, one end of which is connected to the end electrode on the ceramic substrate (901) by high-temperature brazing, and the other end is welded to the external lead wire. The microchannel phase change heat sink assembly (130) is closely attached to the entire bottom of the ceramic substrate (901). The microchannel phase change heat sink assembly (130) includes a whole plate (131), which is an independent copper or silicon plate. The interior of the whole plate is formed with dendritic fractal microchannels (135) by etching or processing. The dendritic fractal microchannels (135) are filled with phase change working fluid. Furthermore, the microchannels are more densely packed below the thick film resistor region, forming a capillary pump structure. The microchannel phase change heat sink assembly (130) is tightly bonded to the bottom of the ceramic substrate (901) by a high thermal conductivity silicone grease or thermal adhesive, and is electrically isolated from the thick film resistor (110) and the thin film resistor (120).

2. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The capillary pump structure in the microchannel phase change heat sink assembly (130) is a functionally graded capillary core, whose capillary pore size or surface energy exhibits a gradient change along the direction from the thick film resistive region to the thin film resistive region, so as to generate a stronger directional capillary driving force.

3. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The phase change working medium filled in the tree-like fractal microchannel (135) is a magnetohydrodynamic phase change working medium. A resistor protection shell (100) is provided on the outside of the ceramic substrate (901). A miniature external magnetic field generator (600) for driving the flow of the magnetohydrodynamic phase change working medium is symmetrically installed at both ends of the resistor protection shell (100) along its own central axis.

4. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The flexible metal transition layer (140) has a micro metal strain gauge installed in the metal foil deformation area. The micro metal strain gauge has an independent signal output terminal for connecting to an external monitoring circuit to realize real-time monitoring of the mechanical stress and temperature of the thick film resistor (110) and the thin film resistor (120).

5. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The isolation groove (902) is connected to an isolation groove support rib (903) at its side end. The isolation groove support rib (903) and the ceramic substrate (901) are integrally formed. The isolation groove support rib (903) is provided with a wire groove (904) at its side end.

6. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The side end of the metal connecting plate (800) is connected to a metal cap electrical connection part (700), and the metal cap electrical connection part (700) and the metal cap (400) are integrally formed.

7. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The side ends of the entire board (131) are symmetrically provided with solder joints (132) along its central axis. The side ends of the solder joints (132) are respectively connected to stress monitoring end (133) and temperature monitoring end (134).

8. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 1, characterized in that: The dendritic fractal microchannel (135) is internally equipped with phase change working fluid reservoirs (136) at unequal intervals. These reservoirs (136) store and stably supply the phase change working fluid. The reservoirs (136) are fully connected to the microchannel (135), providing sufficient replenishment of the working fluid during phase change to prevent working fluid shortage and maintain heat dissipation efficiency. Furthermore, the reservoirs (136) can enhance the directional flow driving force of the working fluid through their elasticity or volume change, ensuring a continuous and stable phase change heat dissipation process. The structure is equipped with a microfluidic working fluid outlet (137) and a monitoring interface on the side. The microfluidic working fluid outlet (137) and the monitoring interface serve as circulation channels for the phase change working fluid, enabling directional discharge and replenishment of the working fluid within the microfluidic channel to ensure the continuity of the phase change heat dissipation cycle. On the other hand, they serve as state monitoring interfaces, connecting to temperature sensors and flow sensors to collect the phase change state and flow rate parameters of the working fluid within the microfluidic channel in real time. The feedback data is used to accurately evaluate the heat dissipation effect of the microfluidic phase change heat sink component (130), providing a basis for optimizing the overall resistive structure.

9. The thick-film double-cap resistor assembly that can avoid solder joint breakage according to claim 3, characterized in that: The top of the resistor protection housing (100) is provided with a heat shrink tubing (200), and the top of the heat shrink tubing (200) is connected to a insert (300). The interior of the resistor protection housing (100) is filled with an elastic thermally conductive buffer medium, which completely covers the internal resistor structure, metal cap and lead wire connection.

10. A double-cap resistor, characterized in that, The thick-film double-cap resistor assembly, as described in any one of claims 1-9, is capable of preventing solder joint breakage.

Images