An electrostatic protection device for a high-junction capacitance TVS tube and its packaging process

Abstract

The present invention belongs to the field of semiconductor packaging technology and provides an electrostatic protection device for a high-junction capacitance TVS tube and its packaging process. The electrostatic protection device for a high-junction capacitance TVS tube comprises: a TVS tube wafer, a frame pad, wire bonding wires, a high-capacitance ceramic capacitor, and a plastic package. The TVS tube wafer and the high-capacitance ceramic capacitor are connected via wire bonding wires and integrated and packaged within the plastic package. By integrating and packaging the TVS tube wafer and the high-capacitance ceramic capacitor, the present invention achieves a perfect combination of electrostatic protection and high-junction capacitance characteristics. The packaging process not only improves the device's electrostatic protection capabilities, but also significantly enhances its capacitance performance, resulting in the electrostatic protection device exhibiting superior performance when responding to transient overvoltage shocks.

Description

Technical Field

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

[0002] In electronic devices, electrostatic discharge (ESD) protection is a critical step in ensuring reliability. Electrostatic discharge can cause electronic equipment to malfunction or be damaged, making ESD protection particularly important in high-speed, highly sensitive electronic systems. In existing technologies, TVS (Transient Voltage Suppression) diodes are widely used for ESD protection due to their fast response characteristics. However, TVS diodes have the following limitations: some TVS diodes have low current flow rates, which limits their protective effectiveness; while TVS diodes with higher current flow rates are accompanied by higher clamping voltages, which can cause additional voltage stress on sensitive circuits and affect their normal operation. Furthermore, existing technologies lack an ESD protection solution that offers both high current flow rates and low clamping voltages.

[0003] In electromagnetic compatibility (EMC) rectification, a TVS diode and capacitor in parallel are often used to provide ESD protection for certain circuits. This solution effectively suppresses high-frequency interference and transient voltages by combining the fast response characteristics of the TVS diode with the filtering properties of the capacitor. However, this solution has the following drawbacks: First, the use of discrete components increases the complexity of the PCB layout, potentially affecting the compactness and manufacturability of the overall design. Second, when PCB area is limited, it may not be possible to effectively arrange the capacitor and TVS diode in parallel, making the solution unfeasible.

[0004] In the design of ESD protection for electronic devices, using a TVS diode alone often results in insufficient current flow capacity, making it difficult to meet high protection requirements. To improve protection performance, capacitors (such as 104 capacitors) are often connected in parallel on both sides of the TVS diode to increase current flow capacity. However, this traditional parallel structure presents several issues: the need for additional capacitors occupies PCB area, increasing circuit design complexity; and, when PCB space is limited, it is difficult to achieve an efficient layout, impacting the compactness and manufacturability of the overall design.

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

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

[0007] The present invention provides an electrostatic protection device for a high-junction capacitance TVS tube, comprising:

[0008] TVS tube wafer, frame pad, wire bonding wire, large-capacitance ceramic capacitor and plastic package. The TVS tube wafer and large-capacitance ceramic capacitor are connected through wire bonding wire and integrated into the plastic package.

[0009] Furthermore, the capacitance of the large-capacitance ceramic capacitor 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 the TVS.

[0010] Furthermore, 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 of the nickel layer Ra≤0.3 μm, which is used to support the TVS tube wafer and the large-capacitance ceramic capacitor.

[0011] Furthermore, the wire bonding wire is a gold wire or a copper wire, the bonding tension of the wire bonding wire is ≥5 gf, and the bridge length of the wire bonding wire is ≤1 mm.

[0012] Furthermore, the thermal expansion coefficient of the epoxy molding compound of the plastic package is ≤8ppm / °C, the glass transition temperature is ≥160°C, and the size of the device after packaging is compatible with the DFN 0402 package.

[0013] A packaging process for an electrostatic protection device of a high-junction capacitance TVS tube comprises the following steps:

[0014] Electroplating a nickel layer on the preformed copper frame to form a frame pad;

[0015] Fix the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad through eutectic bonding;

[0016] The cathode of the TVS tube wafer is connected to the negative electrode of the large-capacitance ceramic capacitor using a wire bonding process, and the diameter of the wire bonding wire is 25μm;

[0017] A plastic package is formed by molding low-stress epoxy plastic, and after cutting, the side pads on the exposed side of the plastic package are electroplated with tin-silver alloy.

[0018] Furthermore, the eutectic bonding material is a gold-tin alloy with a melting point of 280° C., and there is no void defect at the bonding interface.

[0019] Furthermore, the electroplating layer of the side pad has a wettability of ≥90%, a roughness Ra ≤0.3μm, and is solder-compatible with the SMT reflow process.

[0020] Furthermore, it also includes testing the electrostatic protection device of the high junction capacitance TVS tube; specifically:

[0021] In an environment with a temperature of 25±1°C and a humidity of ≤30%RH, use an LCR meter to measure the junction capacitance of the ESD protection device of a high junction capacitance TVS tube at a frequency of 1MHz;

[0022] The electrostatic protection performance of high junction capacitance TVS diodes was evaluated under the conditions of applying 8kV contact discharge, with a residual voltage not exceeding 20V and a response time not exceeding 1 nanosecond.

[0023] Furthermore, it also includes: reliability verification of the electrostatic protection device of the high junction capacitance TVS tube, specifically:

[0024] Obtaining an initial junction capacitance value and an initial leakage current; the initial junction capacitance value is obtained based on measurement at a frequency of 1 MHz using an LCR meter; the initial leakage current is obtained using a high resistance meter;

[0025] Set accelerated aging test conditions and reliability failure determination criteria; accelerated aging test conditions include: a constant temperature and humidity chamber at 85°C ± 2°C and 85% RH ± 5%; a rated operating voltage of DC-5V for 1000 hours; sampling junction capacitance and leakage current every 24 hours; and a reliability failure determination algorithm including: the difference between the junction capacitance and the initial junction capacitance is greater than a set difference threshold, or the leakage current is greater than a set current threshold, or the ratio of the leakage current to the initial leakage current is greater than a set ratio threshold.

[0026] Based on the accelerated aging test conditions and reliability failure judgment criteria, the junction capacitance value and leakage current are sampled and reliability failure judgment is made. If a reliability failure is determined, the test duration for which the reliability failure is determined is obtained.

[0027] Based on the test duration, the Arrhenius model is used to predict the life of the ESD protection device of the high junction capacitance TVS tube after a reliability failure. The calculation formula for the predicted life is:

[0028]

[0029] In the above formula, represents the predicted lifespan, 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, 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 occurs; is the Boltzmann constant.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] First, by integrating large-capacitance ceramic capacitors, the electrostatic protection capability of the TVS tube is significantly improved, enabling it to more effectively absorb and disperse electrostatic pulses, thereby protecting the circuit from damage caused by electrostatic discharge (ESD). This design not only improves the electrostatic protection level of the device, but also maintains a smaller package size, meeting the dual needs of modern electronic equipment for miniaturization and high performance.

[0032] Secondly, the use of eutectic bonding technology and wire bonding process ensures a 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, through special treatment of the frame pad, the bonding interface is optimized, further improving the performance of the device.

[0033] In addition, the material selection and process optimization of the plastic package give the device good thermal stability and mechanical strength, enabling it to maintain stable performance in harsh operating environments. At the same time, the encapsulated device size is compatible with the DFN 0402 package, facilitating layout and wiring on the PCB, reducing design and manufacturing costs.

[0034] Finally, through rigorous 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.

[0035] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 This is a schematic diagram of the structure of an electrostatic protection device for a high junction capacitance TVS tube;

[0039] Figure 2 This is a schematic diagram of the circuit structure used for hardware design after integrating the TVS tube wafer;

[0040] Figure 3 The figure is a schematic diagram of the steps of a packaging process for an electrostatic protection device of a high junction capacitance TVS tube. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] The present invention provides an electrostatic protection device for a high junction capacitance TVS tube, such as Figure 1 Shown, including:

[0043] TVS tube wafer, frame pad, wire bonding wire, large-capacitance ceramic capacitor and plastic package. The TVS tube wafer and large-capacitance ceramic capacitor are connected through wire bonding wire and integrated into the plastic package.

[0044] The working principle of the above technical solution is as follows: in order to realize an electrostatic protection device for a high-junction capacitance TVS tube, the present invention adopts a structure in which a TVS tube wafer is connected to a large-capacitance ceramic capacitor through lead bonding wires and integrated into a 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, Figure 2 As shown in the figure, C1 represents a large-capacitance ceramic capacitor. It shows that after integrating the TVS tube wafer and the large-capacitance ceramic capacitor, the use of this integrated device 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.

[0045] The beneficial effect of the above technical solution is: the solution provided in this embodiment can effectively improve the electrostatic protection capability of the TVS tube. By introducing large-capacitance ceramic capacitors, the device's ability to absorb and disperse electrostatic pulses is significantly enhanced, thereby effectively avoiding the problem of TVS tube failure due to electrostatic damage.

[0046] In one embodiment, the large-capacitance ceramic capacitor has a capacitance of 100 pF-10 μF, a dielectric material of barium titanate-based ceramic, a dielectric constant ≥3000, and a withstand voltage greater than 1.5 times the breakdown voltage of the TVS.

[0047] The working principle of the above technical solution is: when the capacitance of the large-capacitance ceramic capacitor is set between 100pF and 10μF, the capacitor can effectively store and release charges and quickly respond to electrostatic pulses, thereby achieving effective protection for the TVS tube; the dielectric material uses barium titanate-based ceramics, which has a high dielectric constant, so that the capacitor can achieve a larger capacitance value in a smaller volume, which is conducive to the miniaturization of the device; at the same time, the high dielectric constant can also increase 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 breakdown voltage of the TVS, ensuring that the capacitor will not break down under the action of electrostatic pulses, thereby maintaining the stability and reliability of the device.

[0048] The beneficial effect of the above technical solution is that the solution provided in this embodiment can not only effectively improve the electrostatic protection capability of the TVS tube, but also further optimize the performance of the device through precise parameter settings, such as the capacitance range of large-capacitance ceramic capacitors, the selection of dielectric materials, and the setting of the withstand voltage value.

[0049] In one embodiment, the surface of the frame pad is plated with a nickel layer having a thickness of 3-5 μm and a surface roughness of Ra ≤ 0.3 μm, for supporting the TVS tube wafer and the large-capacitance ceramic capacitor.

[0050] The working principle of the above technical solution is: the nickel layer has good 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 roughness control of the nickel layer surface helps to enhance the adhesion between the TVS tube wafer and the large-capacitance ceramic capacitor, thereby improving the reliability and stability of the package.

[0051] The beneficial effects of the above technical solution are as follows: by adopting the solution provided in this embodiment, the packaging process of the device is further optimized through fine control of the plating thickness and surface roughness, thereby improving the overall performance of the device.

[0052] In one embodiment, the wire bonding wire is a gold wire or a copper wire, the bonding tension of the wire bonding wire is ≥5 gf, and the jumper length of the wire bonding wire is ≤1 mm.

[0053] The working principle of the above technical solution is as follows: both gold wire and copper wire have good conductivity and mechanical strength, which can ensure stable and reliable electrical connection between TVS tube wafer and large-capacitance ceramic capacitor; bonding tension ≥ 5gf ensures the firmness of lead bonding wire during the packaging process, avoiding connection failure caused by insufficient tension, and jumper length ≤ 1mm helps to reduce the package volume and improve the integration and aesthetics of the package; at the same time, the shorter jumper length also helps to reduce the loss during signal transmission and improve the performance of the device.

[0054] The beneficial effect of the above technical solution is: by adopting the solution provided by this embodiment, by selecting appropriate lead bonding wires and their parameter settings, the connection method between the TVS tube wafer and the large-capacitance ceramic capacitor is further optimized, which not only improves the reliability and stability of the package, but also improves the performance and integration of the device.

[0055] In one embodiment, the thermal expansion coefficient of the epoxy molding compound of the plastic package is ≤8ppm / °C, the glass transition temperature is ≥160°C, and the size of the device after packaging is compatible with the DFN 0402 package.

[0056] The working principle of the above technical solution is as follows: the thermal expansion coefficient of the epoxy molding compound of the plastic package is ≤8ppm / ℃, 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 is ≥160℃, which ensures the stability of the plastic package in high temperature environments and avoids deformation or failure of the plastic package due to temperature increase; the size of the encapsulated device is compatible with the DFN 0402 package, which means that the ESD protection device can be easily integrated into existing electronic systems without additional modification or adjustment to the system, thereby reducing the system integration cost and time.

[0057] The beneficial effect of the above technical solution is: by adopting the solution provided by this embodiment, the packaging performance and compatibility of the TVS tube electrostatic protection device are further enhanced by optimizing the material parameters of the plastic package.

[0058] A packaging process for an electrostatic protection device of a high junction capacitance TVS tube, such as Figure 3 As shown, the following steps are included:

[0059] Electroplating a nickel layer on the preformed copper frame to form a frame pad;

[0060] Fix the TVS tube wafer and the large-capacitance ceramic capacitor to the frame pad through eutectic bonding;

[0061] The cathode of the TVS tube wafer is connected to the negative electrode of the large-capacitance ceramic capacitor using a wire bonding process, and the diameter of the wire bonding wire is 25μm;

[0062] A plastic package is formed by molding low-stress epoxy plastic, and after cutting, the side pads on the exposed side of the plastic package are electroplated with tin-silver alloy.

[0063] The working principle of the above technical solution is as follows: in order to realize a packaging process of an electrostatic protection device for a high-junction capacitance TVS tube, the present invention first electroplates a nickel layer on a preformed copper frame to enhance the conductivity and corrosion resistance of the frame pad, providing a reliable foundation for subsequent packaging steps; the TVS tube wafer and the large-capacitance ceramic capacitor are fixed to the frame pad by eutectic bonding, ensuring the stability and reliability of the device while improving the electrostatic protection capability of the device; the use of the lead 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 the lead bonding wire diameter of 25μm, while ensuring the connection strength, also reduces the package size and improves the package integration; the plastic package formed by molding low-stress epoxy plastic not only protects the electronic components inside the device, but also optimizes the material parameters of the plastic package, further improving the reliability and stability of the package; after cutting, the side pads on the exposed side of the plastic package are electroplated with tin-silver alloy, which 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.

[0064] The beneficial effects of the above technical solution are as follows: the solution provided in this embodiment realizes the integrated packaging of high junction capacitance TVS tube and large capacitance ceramic capacitor, effectively improving the electrostatic protection capability and overall performance of the device; first, the application of the electroplated nickel layer significantly enhances the conductivity and corrosion resistance of the frame pad, ensuring the stable connection of the electronic components during the packaging process; second, the eutectic bonding technology tightly combines the TVS tube wafer with the large capacitance ceramic capacitor, which not only improves the stability of the device, but also significantly enhances its electrostatic protection capability, enabling it to more effectively protect the circuit when facing electrostatic shock; in addition, the use of the lead bonding process and the selection of 25μm diameter lead bonding wire achieve a reduction in package size and an increase in integration while ensuring connection strength, which is conducive to the miniaturization and high-density integration of the device; finally, the plastic package formed by molded low-stress epoxy plastic and the tin-silver alloy electroplating treatment of the side pad further improve the reliability and stability of the package, while enhancing the conductivity, corrosion resistance and solderability of the pad, providing a solid guarantee for the subsequent use of the device.

[0065] In one embodiment, the eutectic bonding material is a gold-tin alloy with a melting point of 280° C., and there is no void defect at the bonding interface.

[0066] The working principle of the above technical solution is as follows: gold-tin alloy, as a eutectic bonding material, can quickly liquefy and fill the tiny gap between the TVS tube wafer and the large-capacitance ceramic capacitor at a melting point of 280°C, forming a strong and uniform bonding interface. In this process, the fluidity of the gold-tin alloy ensures that there are no void defects at the bonding interface, thereby effectively improving the mechanical strength and thermal stability of the device. When electrostatic shock acts on the device, this tight bonding structure can prevent electrostatic energy from accumulating or leaking at the interface, thereby protecting the TVS tube and 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 electrostatic energy, further improving the electrostatic protection capability of the device.

[0067] The beneficial effect of the above technical solution is: adopting the solution provided by this embodiment and using gold-tin alloy as the eutectic bonding material is the key to achieving tight and reliable bonding between high-junction capacitance TVS tubes and large-capacitance ceramic capacitors, and also provides a strong guarantee for the overall performance of the device.

[0068] In one embodiment, the electroplating layer of the side pad has a wettability of ≥90%, a roughness Ra of ≤0.3 μm, and is solder-compatible with an SMT reflow process.

[0069] The working principle of the above technical solution is as follows: after the side pads are specially treated, their electroplating layer exhibits excellent wetting properties, ensuring that the solder can evenly and fully cover the pad surface during the welding process, avoiding the occurrence of poor welding and cold soldering; at the same time, the roughness of the electroplating layer is strictly controlled below 0.3μm. This fine surface treatment not only improves the welding 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.

[0070] The beneficial effects of the above technical solution are: by adopting the solution provided in this embodiment, by optimizing the electroplating layer treatment process of the side pad, the bonding strength between the solder and the pad is significantly improved, laying a solid foundation for the packaging quality and long-term stability of the device; in addition, this fine electroplating layer treatment also makes the welding process more compatible with the SMT reflow process, simplifies the packaging process, improves production efficiency, and reduces manufacturing costs.

[0071] In one embodiment, the electrostatic protection device of the high junction capacitance TVS tube is tested; specifically:

[0072] In an environment with a temperature of 25±1°C and a humidity of ≤30%RH, use an LCR meter to measure the junction capacitance of the ESD protection device of a high junction capacitance TVS tube at a frequency of 1MHz;

[0073] The electrostatic protection performance of high junction capacitance TVS diodes was evaluated under the conditions of applying 8kV contact discharge, with a residual voltage not exceeding 20V and a response time not exceeding 1 nanosecond.

[0074] The working principle of the above technical solution is as follows: During the test process, the junction capacitance value of the ESD protection device of the high-junction capacitance TVS tube at a specified frequency is first accurately measured using an LCR meter. This step ensures that the capacitance characteristics of the device meet the design requirements and provides basic data for subsequent ESD protection performance evaluation. Then, under strict ESD test conditions, the electrostatic shock that may be encountered in actual use is simulated to evaluate the ESD protection capability of the device. By monitoring key indicators such as residual voltage and response time, the stability and reliability of the device in an electrostatic environment can be comprehensively judged.

[0075] The beneficial effect of the above technical solution is that the solution provided by this embodiment not only verifies the rationality of the device design, but also provides important quality assurance for subsequent production and application.

[0076] In one embodiment, the method further includes: performing reliability verification on the electrostatic protection device of the high junction capacitance TVS tube, specifically:

[0077] Obtaining an initial junction capacitance value and an initial leakage current; the initial junction capacitance value is obtained based on measurement at a frequency of 1 MHz using an LCR meter; the initial leakage current is obtained using a high resistance meter;

[0078] Set accelerated aging test conditions and reliability failure determination criteria; accelerated aging test conditions include: a constant temperature and humidity chamber at 85°C ± 2°C and 85% RH ± 5%; a rated operating voltage of DC-5V for 1000 hours; sampling junction capacitance and leakage current every 24 hours; and a reliability failure determination algorithm including: the difference between the junction capacitance and the initial junction capacitance is greater than a set difference threshold, or the leakage current is greater than a set current threshold, or the ratio of the leakage current to the initial leakage current is greater than a set ratio threshold.

[0079] Based on the accelerated aging test conditions and reliability failure judgment criteria, the junction capacitance value and leakage current are sampled and reliability failure judgment is made. If a reliability failure is determined, the test duration for which the reliability failure is determined is obtained.

[0080] Based on the test duration, the Arrhenius model is used to predict the life of the ESD protection device of the high junction capacitance TVS tube after a reliability failure. The calculation formula for the predicted life is:

[0081]

[0082] In the above formula, represents the predicted lifespan, 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, 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 occurs; is the Boltzmann constant.

[0083] The working principle of the above technical solution is as follows: During the use of electrostatic protection devices, their junction capacitance and leakage current are key indicators for measuring the stability of device performance. By subjecting the device to accelerated aging tests to simulate the use of the device in extreme environments, the reliability of the device can be evaluated more quickly. During the test, the junction capacitance and leakage current are regularly sampled and compared with the initial values, so that the degradation trend of device performance can be discovered in a timely manner. Once the junction capacitance or leakage current of the device exceeds the set failure judgment standard, it can be determined that the device has a reliability failure. At this time, the recorded test time, that is, the time the device experiences 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 based on the test time under accelerated aging test conditions. This prediction result has important guiding significance for the selection, use and maintenance of the device.

[0084] The beneficial effects of the above technical solution are as follows: by adopting the solution provided in this embodiment, it is possible to quickly evaluate the performance and predict the life of high-junction capacitance TVS tube electrostatic protection devices; by accelerating aging testing and simulating extreme environmental conditions, the test cycle can be shortened, the test efficiency can be improved, the degradation trend of device performance can be discovered in a timely manner, and system failures caused by device failure 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.

[0085] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

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 large-capacitance ceramic capacitor are connected by wire bonding wire and integrated into the plastic package. The capacitance of large-capacitance 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 TVS breakdown voltage; The surface of the frame pad is plated with a nickel layer with a thickness of 3-5μm and a surface roughness of Ra ≤ 0.3μm, which is used to support TVS tube wafers and large-capacitance ceramic capacitors; 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 DFN0402 package.

2. 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.

3. A packaging process for an electrostatic protection device of a high junction capacitance TVS tube according to any one of claims 1-2, characterized in that: The following steps are involved: Electroplating a nickel layer on the preformed copper frame to form a frame pad; The TVS tube wafer and the large-capacitance ceramic capacitor are fixed to the frame pad through eutectic bonding; the eutectic bonding material is gold-tin alloy with a melting point of 280°C, and there is no void defect at the bonding interface; The cathode of the TVS tube wafer is connected to the negative electrode of the large-capacitance ceramic capacitor using a wire bonding process, and the diameter of the wire bonding wire is 25μm; A plastic package is formed by molding low-stress epoxy plastic, and after cutting, the side pads of the exposed side of the plastic package are electroplated with tin-silver alloy; It also includes: testing the electrostatic protection device of high junction capacitance TVS tube; specifically: In an environment with a temperature of 25±1°C and a humidity of ≤30%RH, use an LCR meter to measure the junction capacitance of the ESD protection device of a high junction capacitance TVS tube at a frequency of 1MHz; Evaluate the ESD protection performance of high junction capacitance TVS diodes under the conditions of applying 8kV contact discharge, with a residual voltage not exceeding 20V and a response time not exceeding 1 nanosecond; It also includes: reliability verification of the electrostatic protection device of the high junction capacitance TVS tube, specifically: Obtaining an initial junction capacitance value and an initial leakage current; the initial junction capacitance value is obtained based on measurement at a frequency of 1 MHz using an LCR meter; the initial leakage current is obtained using 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 at 85°C ± 2°C and 85% RH ± 5%; a rated operating voltage of DC-5V for 1000 hours; sampling junction capacitance and leakage current every 24 hours; and a reliability failure determination algorithm including: the difference between the junction capacitance and the initial junction capacitance is greater than a set difference threshold, or the leakage current is greater than a set current threshold, or the ratio of the leakage current to the initial leakage current is greater than a set ratio threshold. Based on the accelerated aging test conditions and reliability failure judgment criteria, the junction capacitance value and leakage current are sampled and reliability failure judgment is made. If a reliability failure is determined, the test duration for which the reliability failure is determined is obtained. Based on the test duration, the Arrhenius model is used to predict the life of the ESD protection device of the high junction capacitance TVS tube after a reliability failure. The calculation formula for the predicted life is: In the above formula, represents the predicted lifespan, 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, and is used to quantify the sensitivity of the failure mechanism to temperature; represents the absolute temperature of the accelerated aging test conditions, The absolute temperature of the working environment of the electrostatic protection device representing the high junction capacitance TVS tube after reliability failure occurs; is the Boltzmann constant.

4. The packaging process of the electrostatic protection device of the high junction capacitance TVS tube according to claim 3, 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.

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