Electrostatic protection device of high junction capacitance TVS (Transient Voltage Suppressor) tube and packaging process of electrostatic protection device

Abstract

The invention belongs to the technical field of semiconductor packaging, and provides an electrostatic protection device of a high junction capacitance TVS (Transient Voltage Suppressor) tube and a packaging process thereof, the electrostatic protection device of the high junction capacitance TVS tube comprises a TVS tube wafer, a frame bonding pad, a lead bonding wire, a large-capacitance ceramic capacitor and a plastic package body, the TVS tube wafer is connected with the large-capacitance ceramic capacitor through the lead bonding wire, and the TVS tube wafer is connected with the plastic package body through the lead bonding wire. And the components are integrated and packaged in a plastic package body. According to the invention, the TVS tube wafer and the large-capacitance ceramic capacitor are integrated and packaged, so that the perfect combination of electrostatic protection and high junction capacitance characteristics is realized; the packaging process not only improves the electrostatic protection capability of the device, but also remarkably improves the capacitive performance of the device, so that the electrostatic protection device shows more excellent performance when dealing with transient overvoltage impact.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and particularly to an electrostatic protection device for a high junction capacitance TVS tube and its packaging process. Background Art

[0002] In electronic devices, electrostatic discharge (ESD) protection is a crucial link to ensure reliability. Electrostatic discharge may cause the failure or damage of the functions of electronic devices. Especially in high-speed and high-sensitivity electronic systems, ESD protection is particularly important. In the prior art, TVS tubes (Transient Voltage Suppression) are widely used in ESD protection due to their fast response characteristics. However, TVS tubes have the following limitations: some TVS tubes have a small current-carrying capacity, resulting in limited protection effects; while TVS tubes with a larger current-carrying capacity are accompanied by a higher clamping voltage, which may cause additional voltage stress on sensitive circuits and affect their normal operation. In addition, there is a lack of an ESD protection solution in the prior art that can provide both a large current-carrying capacity and a low clamping voltage.

[0003] In electromagnetic compatibility (EMC) rectification, a combined solution of a TVS tube and a capacitor in parallel is usually adopted to achieve electrostatic protection for some circuits. This solution combines the fast response characteristics of the TVS tube and the filtering characteristics of the capacitor, and can effectively suppress high-frequency interference and transient voltages. However, this solution has the following disadvantages: firstly, the use of discrete devices increases the complexity of PCB layout design, which may affect the overall design compactness and manufacturability; secondly, in the case of limited PCB area, it may not be possible to effectively layout the parallel capacitor and the TVS tube, resulting in the inability to implement the solution.

[0004] In the electrostatic protection design of electronic devices, when using a TVS tube alone, its current-carrying capacity is often insufficient to meet high protection requirements. In order to improve the protection performance, in engineering practice, a capacitor (such as a 104 capacitor) is usually connected in parallel on both sides of the TVS tube to increase the current-carrying capacity. However, this traditional parallel structure has the following problems: it is necessary to install an additional capacitor, which occupies PCB area and increases the complexity of circuit design; in the case of limited PCB space, it is difficult to achieve an efficient layout, affecting the overall design compactness and manufacturability.

[0005] Therefore, it is necessary to provide an electrostatic protection device for a high junction capacitance TVS tube and its packaging process. Summary of the Invention

[0006] The present invention provides an electrostatic protection device for a high-junction-capacitance TVS tube and its packaging process. By integrating and packaging the TVS tube wafer with a large-capacitance ceramic capacitor, the perfect combination of electrostatic protection and high-junction-capacitance characteristics is achieved. The packaging process not only improves the electrostatic protection ability of the device but also significantly enhances its capacitance performance, enabling the device to exhibit more excellent performance when dealing with transient overvoltage impacts.

[0007] The present invention provides an electrostatic protection device for a high-junction-capacitance TVS tube, comprising: a TVS tube wafer, a frame pad, a wire bonding wire, a large-capacitance ceramic capacitor, and a plastic package. The TVS tube wafer is connected to the large-capacitance ceramic capacitor through the wire bonding wire and is integrally packaged in the plastic package.

[0008] Further, the capacitance value of the large-capacitance ceramic capacitor is 100 pF - 10 μF, the dielectric material is barium titanate-based ceramic, the dielectric constant ≥ 3000, and the withstand voltage value is more than 1.5 times the TVS breakdown voltage.

[0009] Further, the surface of the frame pad is plated with a nickel layer, the thickness of the nickel layer is 3 - 5 μm, and the surface roughness Ra of the nickel layer ≤ 0.3 μm, which is used to support the TVS tube wafer and the large-capacitance ceramic capacitor.

[0010] Further, the wire bonding wire is a gold wire or a copper wire, the bonding force of the wire bonding wire ≥ 5 gf, and the bridging length of the wire bonding wire ≤ 1 mm.

[0011] Further, the coefficient of thermal expansion of the epoxy molding compound of the plastic package ≤ 8 ppm / °C, the glass transition temperature ≥ 160 °C, and the size of the packaged device is compatible with the DFN 0402 package.

[0012] A packaging process for an electrostatic protection device of a high-junction-capacitance TVS tube comprises the following steps: Electroplating a nickel layer on a preformed copper frame to form a frame pad; Fixing the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad through eutectic bonding; Adopting a wire bonding process to connect the cathode of the TVS tube wafer and the negative electrode of the large-capacitance ceramic capacitor, and the diameter of the wire bonding wire is 25 μm; Forming a plastic package through a low-stress epoxy plastic for molding, and performing tin-silver alloy electroplating treatment on the side pads of the exposed sides of the plastic package after cutting.

[0013] Further, the eutectic bonding material is a gold-tin alloy, the melting point is 280 °C, and there are no void defects at the bonding interface.

[0014] Further, the wettability of the electroplated layer of the side pad ≥ 90%, the roughness Ra ≤ 0.3 μm, and the welding is compatible with the SMT reflow process.

[0015] Further, it also includes testing the electrostatic protection device of the high-junction-capacitance TVS tube; specifically: In an environment with a temperature of 25 ± 1°C and a humidity ≤ 30%RH, use an LCR tester to measure the junction capacitance of the electrostatic protection device of the high-junction-capacitance TVS tube at a frequency of 1 MHz. Under the conditions of applying 8 kV contact discharge, with a residual voltage not exceeding 20 V and a response time not exceeding 1 nanosecond, evaluate the electrostatic protection performance of the high-junction-capacitance TVS tube.

[0016] Further, it also includes: verifying the reliability of the electrostatic protection device of the high-junction-capacitance TVS tube, specifically: Obtain the initial junction capacitance value and the initial leakage current; the initial junction capacitance value is obtained based on the measurement by an LCR tester at a frequency of 1 MHz; the initial leakage current is obtained by measuring with a high-resistance meter. Set the accelerated aging test conditions and the reliability failure determination criteria; the accelerated aging test conditions include: a thermo-hygrostat with a temperature of 85°C ± 2°C and a humidity of 85%RH ± 5%; a rated working voltage of DC - 5V and lasting for 1000 hours; sample the junction capacitance value and the leakage current every 24 hours; the reliability failure determination algorithm includes: the difference between the junction capacitance value and the initial junction capacitance value is greater than the set difference threshold, or the leakage current is greater than the set current threshold, or the ratio of the leakage current to the initial leakage current is greater than the set ratio threshold. Based on the accelerated aging test conditions and the reliability failure determination criteria, sample the junction capacitance value and the leakage current and determine the reliability failure. If it is determined as a reliability failure, obtain the test duration determined as a reliability failure. Based on the test duration, use the Arrhenius model to predict the predicted life of the electrostatic protection device of the high-junction-capacitance TVS tube after the occurrence of reliability failure; the calculation formula for the predicted life is: In the above formula, represents the predicted life, represents the test duration, represents the activation energy of the failure mechanism, which represents the minimum energy required for the reactant molecules of the electrostatic protection device to change from the initial state to the activated state, and is used to quantify the sensitivity of the failure mechanism to temperature; represents the absolute temperature of the accelerated aging test conditions, represents the absolute temperature of the working environment of the electrostatic protection device of the high-junction-capacitance TVS tube after the occurrence of reliability failure; is the Boltzmann constant.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: First, by integrating large-capacitance ceramic capacitors, the electrostatic protection ability of the TVS tube is significantly improved, enabling it to more effectively absorb and disperse electrostatic pulses, thereby protecting the circuit from electrostatic discharge (ESD) damage. This design not only improves the electrostatic protection level of the device but also maintains a small package size, meeting the dual requirements of miniaturization and high performance in modern electronic devices.

[0018] Secondly, the eutectic bonding technology and wire bonding process are adopted to ensure the stable connection between the TVS tube wafer and the large-capacitance ceramic capacitor, improving the reliability and durability of the device. At the same time, by specially treating the frame pads, the bonding interface is optimized, further enhancing the performance of the device.

[0019] In addition, the material selection and process optimization of the plastic package make the device have good thermal stability and mechanical strength, enabling it to maintain stable performance in harsh working environments. At the same time, the size of the packaged device is compatible with the DFN 0402 package, facilitating layout and wiring on the PCB and reducing design and manufacturing costs.

[0020] Finally, through strict testing and reliability verification, the stability and reliability of the electrostatic protection device of the high-junction-capacitance TVS tube in practical applications are ensured.

[0021] Other features and advantages of the present invention will be described in the following specification, and some will become obvious from the specification or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings.

[0022] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings: Figure 1 It is a schematic structural diagram of an electrostatic protection device for a high-junction-capacitance TVS tube; Figure 2 It is a schematic circuit structure diagram for hardware design after integrating the TVS tube wafer; Figure 3 It is a schematic diagram of the method steps of the packaging process of an electrostatic protection device for a high-junction-capacitance TVS tube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0025] The present invention provides an electrostatic protection device for a high junction capacitance TVS tube, as Figure 1 shown, including: A TVS tube wafer, a frame pad, a wire bonding wire, a large capacitance ceramic capacitor, and a plastic package. The TVS tube wafer is connected to the large capacitance ceramic capacitor through the wire bonding wire and is integrally packaged in the plastic package.

[0026] The working principle of the above technical solution is: In order to implement an electrostatic protection device for a high junction capacitance TVS tube, the present invention adopts a structure in which the TVS tube wafer is connected to the large capacitance ceramic capacitor through the wire bonding wire and is integrally packaged in the plastic package; when an electrostatic pulse acts on the device, the large capacitance ceramic capacitor can quickly absorb and disperse the electrostatic energy, thereby protecting the TVS tube from electrostatic damage; at the same time, as Figure 2 shown, C1 in the figure represents the large capacitance ceramic capacitor. It shows that after integrating the TVS tube wafer and the large capacitance ceramic capacitor, when using this integrated device, it is more convenient in hardware design. The plastic package provides good mechanical support and environmental protection for the entire device, ensuring the stability and reliability of the device.

[0027] The beneficial effects of the above technical solution are: By adopting the solution provided in this embodiment, the electrostatic protection ability of the TVS tube can be effectively improved. Through the introduction of the large capacitance ceramic capacitor, the ability of the device to absorb and disperse electrostatic pulses is significantly enhanced, thereby effectively avoiding the problem of the TVS tube failing due to electrostatic damage.

[0028] In one embodiment, the capacitance value of the large capacitance ceramic capacitor is 100 pF - 10 μF, the dielectric material is barium titanate-based ceramic, the dielectric constant ≥ 3000, and the withstand voltage value is more than 1.5 times the TVS breakdown voltage.

[0029] The working principle of the above technical solution is: When the capacitance value of the large capacitance ceramic capacitor is set between 100 pF and 10 μF, the capacitor can effectively store and release charges and quickly respond to electrostatic pulses, thereby realizing effective protection for the TVS tube; the dielectric material uses barium titanate-based ceramic, because it has a high dielectric constant, enabling the capacitor to achieve a large capacitance value in a smaller volume, which is beneficial to the miniaturization of the device; at the same time, the high dielectric constant can also improve the energy storage density of the capacitor, further enhancing its ability to absorb electrostatic energy; the withstand voltage value is set to more than 1.5 times the TVS breakdown voltage, ensuring that the capacitor will not break down under the action of electrostatic pulses, thereby maintaining the stability and reliability of the device.

[0030] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, not only can the electrostatic protection ability of the TVS tube be effectively improved, but also the performance of the device is further optimized through fine parameter settings, such as the capacitance range of the large-capacitance ceramic capacitor, the selection of dielectric materials, and the setting of the breakdown voltage value.

[0031] In one embodiment, the surface of the frame pad is plated with a nickel layer, the thickness of the nickel layer is 3 - 5 μm, and the surface roughness Ra of the nickel layer ≤ 0.3 μm, which is used to support the TVS tube wafer and the large-capacitance ceramic capacitor.

[0032] The working principle of the above technical solution is as follows: The nickel layer has good electrical conductivity and corrosion resistance, which can ensure a stable connection between the TVS tube wafer and the large-capacitance ceramic capacitor; at the same time, the control of the surface roughness of the nickel layer helps to enhance the adhesion to the TVS tube wafer and the large-capacitance ceramic capacitor, improving the reliability and stability of the package.

[0033] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, through fine control of the plating thickness and surface roughness, the packaging process of the device is further optimized, and the overall performance of the device is improved.

[0034] In one embodiment, the wire bonding wire is a gold wire or a copper wire, the bonding force of the wire bonding wire ≥ 5 gf, and the bridging length of the wire bonding wire ≤ 1 mm.

[0035] The working principle of the above technical solution is as follows: Both gold wires and copper wires have good electrical conductivity and mechanical strength, which can ensure a stable and reliable electrical connection between the TVS tube wafer and the large-capacitance ceramic capacitor; a bonding force ≥ 5 gf ensures the firmness of the wire bonding wire during the packaging process, avoiding connection failures caused by insufficient force, and a bridging length ≤ 1 mm helps to reduce the packaging volume, improve the integration and aesthetics of the package; at the same time, the shorter bridging length also helps to reduce signal transmission losses and improve the performance of the device.

[0036] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, through the selection of appropriate wire bonding wires and their parameter settings, the connection method between the TVS tube wafer and the large-capacitance ceramic capacitor is further optimized, not only improving the reliability and stability of the package, but also enhancing the performance and integration of the device.

[0037] In one embodiment, the epoxy molding compound of the plastic package has a thermal expansion coefficient ≤ 8 ppm / °C and a glass transition temperature ≥ 160 °C, and the size of the packaged device is compatible with the DFN 0402 package.

[0038] The working principle of the above technical solution is as follows: The epoxy molding compound of the plastic package has a coefficient of thermal expansion ≤ 8 ppm / °C, ensuring that the plastic package has a small dimensional change when the temperature changes, thereby reducing the internal stress caused by thermal expansion and improving the reliability and stability of the package; the glass transition temperature ≥ 160 °C guarantees the stability of the plastic package in a high-temperature environment and avoids the deformation or failure of the plastic package caused by temperature rise; the device size after packaging is compatible with the DFN 0402 package, meaning that this electrostatic protection device can be easily integrated into the existing electronic system without additional modification or adjustment to the system, thus reducing the integration cost and time of the system.

[0039] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment and optimizing the material parameters of the plastic package, the packaging performance and compatibility of the TVS tube electrostatic protection device are further enhanced.

[0040] A packaging process for an electrostatic protection device of a high-junction-capacitance TVS tube, as Figure 3 shown, includes the following steps: Electroplate a nickel layer on the preformed copper frame to form a frame pad; Fix the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad by eutectic bonding; Use the wire bonding process to connect the cathode of the TVS tube wafer and the negative electrode of the large-capacitance ceramic capacitor. The diameter of the wire bonding wire is 25 μm; Form a plastic package through low-stress epoxy plastic, and perform tin-silver alloy electroplating treatment on the side pads of the exposed sides of the plastic package after cutting.

[0041] The working principle of the above technical solution is as follows: In order to implement a packaging process for an electrostatic protection device of a high-junction-capacitance TVS tube, the present invention first electroplates a nickel layer on the preformed copper frame, enhancing the conductivity and corrosion resistance of the frame pad and providing a reliable basis for subsequent packaging steps; fixing the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad by eutectic bonding ensures the stability and reliability of the device and improves the electrostatic protection ability of the device at the same time; the use of the wire bonding process not only realizes the electrical connection between the cathode of the TVS tube wafer and the negative electrode of the large-capacitance ceramic capacitor, but also the selection of a wire bonding wire with a diameter of 25 μm reduces the packaging size while ensuring the connection strength and improves the integration degree of the packaging; the plastic package formed through low-stress epoxy plastic not only protects the internal electronic components of the device, but also the optimization of the material parameters of the plastic package further improves the reliability and stability of the packaging; performing tin-silver alloy electroplating treatment on the side pads of the exposed sides of the plastic package after cutting not only improves the conductivity of the pads, but also enhances the corrosion resistance and solderability of the pads, providing a good interface for the subsequent use of the device.

[0042] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, the integrated packaging of a high-junction-capacitance TVS tube and a large-capacitance ceramic capacitor is realized, effectively improving the electrostatic protection ability and overall performance of the device. First, the application of the nickel plating layer significantly enhances the conductivity and corrosion resistance of the frame pads, ensuring the stable connection of electronic components during the packaging process. Second, the eutectic bonding technology tightly combines the TVS tube wafer with the large-capacitance ceramic capacitor, not only improving the stability of the device but also significantly enhancing its electrostatic protection ability, enabling it to more effectively protect the circuit when facing electrostatic shocks. In addition, the use of the wire bonding process and the selection of a 25-μm-diameter wire bonding wire reduce the packaging size and improve the integration degree while ensuring the connection strength, which is beneficial to the miniaturization and high-density integration of the device. Finally, the plastic package formed by the low-stress epoxy plastic and the tin-silver alloy electroplating treatment of the side pads further improve the reliability and stability of the packaging, while enhancing the conductivity, corrosion resistance, and solderability of the pads, providing a solid guarantee for the subsequent use of the device.

[0043] In one embodiment, the eutectic bonding material is a gold-tin alloy with a melting point of 280 °C and no void defects at the bonding interface.

[0044] The working principle of the above technical solution is as follows: As the eutectic bonding material, the gold-tin alloy can quickly liquefy at the melting point of 280 °C and fill the tiny gaps between the TVS tube wafer and the large-capacitance ceramic capacitor, forming a firm and uniform bonding interface. During this process, the fluidity of the gold-tin alloy ensures that no void defects are generated at the bonding interface, thus effectively improving the mechanical strength and thermal stability of the device. When an electrostatic shock acts on the device, this tight bonding structure can prevent the electrostatic energy from accumulating or leaking at the interface, thereby protecting the TVS tube and the large-capacitance ceramic capacitor from damage. In addition, the excellent conductivity of the gold-tin alloy also ensures that the TVS tube can quickly respond and absorb the electrostatic energy, further enhancing the electrostatic protection ability of the device.

[0045] The beneficial effects of the above technical solution are as follows: Adopting the gold-tin alloy as the eutectic bonding material in the solution provided in this embodiment is the key to achieving a tight and reliable bond between the high-junction-capacitance TVS tube and the large-capacitance ceramic capacitor, and also provides a strong guarantee for the overall performance of the device.

[0046] In one embodiment, the wettability of the electroplated layer on the side pads is ≥90%, the roughness Ra ≤ 0.3 μm, and the soldering is compatible with the SMT reflow process.

[0047] The working principle of the above technical solution is as follows: After the side pads are specially treated, their plating layers exhibit excellent wetting properties, ensuring that the solder can evenly and fully cover the surface of the pads during the soldering process, avoiding poor soldering and solder joint voids. At the same time, the roughness of the plating layer is strictly controlled below 0.3μm. This fine surface treatment not only improves the soldering quality of the pads but also helps to enhance the mechanical bonding force between the solder joints and the pads, thereby improving the reliability of the entire device.

[0048] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment and optimizing the plating layer treatment process of the side pads, the bonding strength between the solder and the pads is significantly improved, laying a solid foundation for the packaging quality and long-term stability of the device. In addition, this fine plating layer treatment also makes the soldering process more compatible with the SMT reflow process, simplifies the packaging process, improves production efficiency, and reduces manufacturing costs.

[0049] In one embodiment, it also includes testing the electrostatic protection device of the high junction capacitance TVS tube; specifically: In an environment with a temperature of 25 ± 1°C and a humidity ≤ 30%RH, use an LCR tester to measure the junction capacitance of the electrostatic protection device of the high junction capacitance TVS tube at a frequency of 1MHz. Under the conditions of applying 8kV contact discharge, with a residual voltage not exceeding 20V and a response time not exceeding 1 nanosecond, evaluate the electrostatic protection performance of the high junction capacitance TVS tube.

[0050] The working principle of the above technical solution is as follows: During the testing process, first, accurately measure the junction capacitance value of the electrostatic protection device of the high junction capacitance TVS tube at a specified frequency through an LCR meter. This step ensures that the capacitance characteristics of the device meet the design requirements and provides basic data for subsequent evaluation of the electrostatic protection performance. Then, under strict electrostatic discharge test conditions, simulate the electrostatic shocks that may be encountered in actual use, evaluate the ESD protection ability of the device, and comprehensively judge the stability and reliability of the device in an electrostatic environment by monitoring key indicators such as residual voltage and response time.

[0051] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, not only the rationality of the device design is verified, but also important quality assurance is provided for subsequent production and application.

[0052] In one embodiment, it also includes: verifying the reliability of the electrostatic protection device of the high junction capacitance TVS tube, specifically: Obtain the initial junction capacitance value and the initial leakage current; the initial junction capacitance value is measured based on an LCR tester at a frequency of 1MHz; the initial leakage current is measured through a high resistance meter. Set the accelerated aging test conditions and the reliability failure determination criteria; the accelerated aging test conditions include: a thermostatic and humidistatic chamber with a temperature of 85°C ± 2°C and a humidity of 85%RH ± 5%; a rated working voltage of DC - 5V for 1000 hours continuously; sampling the junction capacitance value and leakage current every 24 hours; the reliability failure determination algorithm includes: the difference between the junction capacitance value and the initial junction capacitance value is greater than the set difference threshold, or the leakage current is greater than the set current threshold, or the ratio of the leakage current to the initial leakage current is greater than the set ratio threshold; Based on the accelerated aging test conditions and the reliability failure determination criteria, sample the junction capacitance value and leakage current and conduct reliability failure determination. If it is determined as a reliability failure, obtain the test duration determined as a reliability failure; Based on the test duration, use the Arrhenius model to predict the predicted life of the electrostatic protection device of the high - junction - capacitance TVS tube after reliability failure; the calculation formula for the predicted life is: In the above formula, represents the predicted life, represents the test duration, represents the activation energy of the failure mechanism, which represents the minimum energy required for the reactant molecules of the electrostatic protection device to change from the initial state to the activated state and is used to quantify the sensitivity of the failure mechanism to temperature; represents the absolute temperature of the accelerated aging test conditions, represents the absolute temperature of the working environment of the electrostatic protection device of the high - junction - capacitance TVS tube after reliability failure; is the Boltzmann constant.

[0053] The working principle of the above technical solution is as follows: During the use of the electrostatic protection device, its junction capacitance value and leakage current are key indicators to measure the performance stability of the device. By conducting an accelerated aging test on the device to simulate the use of the device in an extreme environment, the reliability of the device can be evaluated more quickly; during the test, regularly sample the junction capacitance value and leakage current and compare them with the initial values to promptly detect the degradation trend of the device performance; once the junction capacitance value or leakage current of the device exceeds the set failure determination criteria, it can be determined that the device has a reliability failure. At this time, the recorded test duration, that is, the time experienced by the device from the start of the test to failure, is an important basis for subsequent life prediction; based on the Arrhenius model, the predicted life of the device in the future working environment can be calculated according to the test duration under the accelerated aging test conditions, and this prediction result has important guiding significance for the selection, use, and maintenance of the device.

[0054] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, it is possible to achieve rapid evaluation and life prediction of the performance of electrostatic protection devices for high junction capacitance TVS tubes; through accelerated aging tests and simulating extreme environmental usage conditions, the test cycle can be shortened, the test efficiency can be improved, the degradation trend of device performance can be detected in a timely manner, and system failures caused by device failures in actual applications can be avoided; at the same time, life prediction based on the Arrhenius model can provide a scientific basis for device selection, use, and maintenance, ensuring the stability and reliability of system operation.

[0055] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. An electrostatic protection device for a high junction capacitance TVS tube, characterized in that: include: TVS tube wafer, frame pad, wire bonding wire, large-capacitance ceramic capacitor and plastic package. The TVS tube wafer and the large-capacitance ceramic capacitor are connected through wire bonding wire and integrated into the plastic package.

2. The electrostatic protection device for a high junction capacitance TVS tube according to claim 1, characterized in that: The capacitance of large-value ceramic capacitors is 100pF-10μF, the dielectric material is barium titanate-based ceramic, the dielectric constant is ≥3000, and the withstand voltage is more than 1.5 times the breakdown voltage of TVS.

3. The electrostatic protection device for a high junction capacitance TVS tube according to claim 1, characterized in that: The surface of the frame pad is plated with a nickel layer with a thickness of 3-5 μm and a surface roughness of Ra≤0.3 μm, which is used to support TVS tube wafers and large-capacitance ceramic capacitors.

4. The electrostatic protection device for a high junction capacitance TVS tube according to claim 1, characterized in that: The wire bonding wire is a gold wire or a copper wire, the bonding tension of the wire bonding wire is ≥5gf, and the jumper length of the wire bonding wire is ≤1mm.

5. The electrostatic protection device for a high junction capacitance TVS tube according to claim 1, characterized in that: The thermal expansion coefficient of the epoxy molding compound of the plastic package is ≤8ppm / ℃, and the glass transition temperature is ≥160℃. The device size after packaging is compatible with the DFN 0402 package.

6. A packaging process for an electrostatic protection device of a high junction capacitance TVS tube according to any one of claims 1 to 5, characterized in that: The following steps are involved: Electroplating a nickel layer on the preformed copper frame to form a frame pad; Fix the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad through eutectic bonding; The wire bonding process is used to connect the cathode of the TVS tube wafer and the negative electrode of the large-capacitance ceramic capacitor. The diameter of the wire bonding wire is 25μm. A plastic package is formed by molding low-stress epoxy plastic, and a tin-silver alloy electroplating treatment is performed on the side pads of the exposed side of the plastic package after cutting.

7. The packaging process of the electrostatic protection device of the high junction capacitance TVS tube according to claim 6, characterized in that: The eutectic bonding material is gold-tin alloy with a melting point of 280°C and no void defects at the bonding interface.

8. The packaging process of the electrostatic protection device of the high junction capacitance TVS tube according to claim 6, characterized in that: The wettability of the electroplating layer of the side pad is ≥90%, the roughness Ra≤0.3μm, and the welding is compatible with the SMT reflow process.

9. The packaging process of the electrostatic protection device of the high junction capacitance TVS tube according to claim 6, characterized in that: Also includes: Test the electrostatic protection device of high junction capacitance TVS tube; specifically: In an environment with a temperature of 25±1℃ and a humidity of ≤30%RH, use an LCR tester to measure the junction capacitance of the electrostatic protection device of the high junction capacitance TVS tube at a frequency of 1MHz; The electrostatic protection performance of high junction capacitance TVS tube is evaluated under the conditions of applying 8kV contact discharge, residual voltage not exceeding 20V, and response time not exceeding 1 nanosecond.

10. The packaging process of the electrostatic protection device of the high junction capacitance TVS tube according to claim 6, characterized in that: Also includes: Reliability verification of the electrostatic protection device of the high junction capacitance TVS tube is carried out as follows: Obtaining an initial junction capacitance value and an initial leakage current; the initial junction capacitance value is obtained by measuring with an LCR tester at a frequency of 1 MHz; the initial leakage current is obtained by measuring with a high resistance meter; Set accelerated aging test conditions and reliability failure determination criteria; Accelerated aging test conditions include: a constant temperature and humidity chamber with a temperature of 85℃±2℃ and a humidity of 85%RH±5%; a rated working voltage of DC-5V and a duration of 1000 hours; sampling of junction capacitance and leakage current every 24 hours; reliability failure judgment algorithm includes: the difference between the junction capacitance value and the initial junction capacitance value is greater than the set difference threshold, or the leakage current is greater than the set current threshold, or the ratio of the leakage current to the initial leakage current is greater than the set ratio threshold; Based on the accelerated aging test conditions and reliability failure judgment criteria, the junction capacitance value and the leakage current are sampled and the reliability failure is judged. If it is judged to be a reliability failure, the test time for which it is judged to be a reliability failure is obtained; Based on the test duration, the Arrhenius model is used to predict the life of the electrostatic protection device of the high junction capacitance TVS tube after reliability failure. The calculation formula for the predicted life is: In the above formula, represents the predicted life span, Represents the test duration, The activation energy of the failure mechanism represents the minimum energy required for the reactant molecules of the ESD protection device to transform from the initial state to the activated state, which is used to quantify the sensitivity of the failure mechanism to temperature; represents the absolute temperature of the accelerated aging test conditions, Represents the absolute temperature of the working environment of the electrostatic protection device of the high junction capacitance TVS tube after reliability failure occurs; is the Boltzmann constant.

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