Shield suitable for wide temperature range and resistant to strong electromagnetic interference and sensing device packaging structure

Abstract

The invention relates to a shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference and a sensing device packaging structure, the shielding body is provided with a shielding cavity for accommodating a sensing device, and the shielding body contains an anti-electromagnetic interference material. The sensing device is arranged in the shielding cavity of the shielding body, and the sensing device is isolated from the external environment, so that stress or deformation caused by temperature change of the external environment or a packaging material cannot act on the sensing device, and the long-term reliability of the sensing device in a wide-temperature-range use environment is improved; and meanwhile, the shielding body contains an anti-electromagnetic interference material, so that the interference of an external electromagnetic field on the sensing device is reduced, and the conditions that the sensitivity of the sensing device is changed and the reliability is reduced in a strong electromagnetic interference environment are avoided.

Description

Technical Field

[0001] The present invention belongs to the field of sensor device packaging, and in particular relates to a shielding body and a sensor device packaging structure which are applicable to a wide temperature range and resistant to strong electromagnetic interference. Background Art

[0002] Currently, the packaging forms of power sensors mainly include ceramic packaging and plastic packaging. Plastic packaging is widely used due to its high cost performance.

[0003] In the existing plastic encapsulation structure, the plastic encapsulation is in direct contact with the sensor device and the bonding wire. In practical applications, there are the following problems: the conductivity, magnetic permeability, dielectric constant and other parameters of ordinary plastic encapsulation materials cannot form electromagnetic shielding for the sensor device and the bonding metal wire, making it difficult to isolate strong external electromagnetic interference. In addition, in the traditional structure, the thermal expansion coefficient of the plastic encapsulation material is relatively high, which is greatly different from the thermal expansion coefficient of the material of the sensor device and the bonding metal wire. The bonding metal wire is soft and easy to deform. In the high and low temperature impact, the plastic encapsulation material will induce stress and strain in the sensor device and the gold wire, thereby affecting the long-term reliability.

[0004] In terms of the safety protection of power systems, sensor devices are often used, and accurate sensor data is crucial for timely detection of potential fault hazards. However, in the complex electromagnetic environment of the power system, traditional sensors are susceptible to strong electromagnetic interference, resulting in signal distortion, increased measurement errors, and even equipment failure. In addition, the working environment temperature of the power system varies greatly, ranging from extremely cold to extremely hot conditions, which places higher requirements on the performance of sensor devices at low or high temperatures. Therefore, it is urgent to develop a sensor device packaging structure that can adapt to a wide temperature range and has the ability to resist strong electromagnetic interference. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the existing packaging structure is difficult to isolate strong external electromagnetic interference and the plastic package body will induce stress and strain in the sensor device and the bonding wire under high and low temperature impact.

[0006] The purpose of the present invention is to adopt the following technical solutions to achieve:

[0007] A shielding body suitable for a wide temperature range and resistant to strong electromagnetic interference, the shielding body having a shielding cavity for accommodating a sensor device, and the shielding body containing an anti-electromagnetic interference material.

[0008] Furthermore, the shielding body is made of the anti-electromagnetic interference material.

[0009] Furthermore, the surface of the shielding body is coated with the anti-electromagnetic interference material.

[0010] Furthermore, the shielding body is filled with the anti-electromagnetic interference material.

[0011] Furthermore, the shielding body has an interlayer, and the interlayer is filled with anti-electromagnetic interference material.

[0012] Furthermore, the interlayers are multiple and are respectively filled with different anti-electromagnetic interference materials.

[0013] Furthermore, the shielding body is provided with a through hole for filling the anti-electromagnetic interference material.

[0014] Furthermore, the main body of the shielding body is made of 3D printing resin.

[0015] Based on the same inventive concept, the present invention also provides a sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference, characterized in that it includes the shielding body suitable for a wide temperature range and resistant to strong electromagnetic interference, and the packaging structure includes:

[0016] Lead frame;

[0017] A sensor device, fixed to the lead frame and realizing external electrical connection through the lead frame;

[0018] A shielding body, fixed to the lead frame and forming a shielding cavity for accommodating the sensor device;

[0019] The plastic sealing body covers the outer side of the shielding body.

[0020] Furthermore, the packaging structure further includes bonding wires;

[0021] One end of the bonding wire is connected to the sensor device, and the other end is connected to the lead frame, so as to realize the electrical connection between the sensor device and the lead frame.

[0022] Furthermore, the bonding wire is located in a shielding cavity formed by the shielding body and the lead frame.

[0023] Furthermore, the shielding body is fixed on the lead frame by means of insulating glue.

[0024] The bonding wire is connected to the sensor device and the lead frame by welding.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes a shielding body suitable for a wide temperature range and resistant to strong electromagnetic interference, which is used to provide electromagnetic shielding protection for a sensor device. The shielding body has a shielding cavity for accommodating the sensor device and contains anti-electromagnetic interference materials. By placing the sensor device in the shielding cavity of the shielding body, the sensor device is isolated from the external environment, so that the stress or deformation caused by temperature changes in the external environment or packaging materials cannot act on the sensor device, thereby improving the long-term reliability of the sensor device in a wide temperature range use environment; at the same time, the shielding body contains anti-electromagnetic interference materials, which reduces the interference of the external electromagnetic field on the sensor device, and avoids the situation where the sensitivity of the sensor device changes and the reliability is reduced in a strong electromagnetic interference environment.

[0027] The shielding body of the present invention can be provided with a multi-layer electromagnetic shielding structure, which is filled with different electromagnetic shielding materials respectively, and the electromagnetic parameters gradually change, thereby achieving smoother impedance matching and more effective absorption of electromagnetic waves.

[0028] The present invention uses 3D printing resin to make the shielding body, so that the structure has a high degree of accuracy and a complex and customizable internal structure. A sandwich is set inside it for filling various electromagnetic shielding materials. In the power system, different application scenarios face electromagnetic shocks of different intensities and types, and the electromagnetic shock parameters vary. The existing plastic package packaging form is not specially designed for the power system environment, and it is inevitable to encounter various new problems when used in the power system. This special structural design makes it possible to flexibly adjust the type and ratio of electromagnetic shielding materials according to actual conditions.

[0029] The present invention also proposes a sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference. By arranging a shielding body outside the bonding wire and the sensor device, the shielding body isolates the sensor device, the bonding wire and the plastic package material, thereby overcoming the problems of direct contact between the plastic package and the sensor device and the bonding wire, mismatch in thermal expansion of the materials, stress concentration and deformation of the sensor device and the bonding wire caused by high and low temperature changes in the traditional plastic package, and improving the long-term reliability of the sensor device in a wide temperature range environment.

[0030] The sensor device packaging structure described in the present invention, the shielding body is made of anti-electromagnetic interference material, or the surface is coated with anti-electromagnetic interference material, or the interior is filled with anti-electromagnetic interference material, which overcomes the problem of poor anti-electromagnetic interference performance of the plastic package in the prior art, and achieves the effect of reducing the electromagnetic field interference of the external electromagnetic field on the sensor device and the bonding wire, and avoids the situation where the sensitivity of the sensor device changes and the reliability is reduced in a strong electromagnetic interference environment. For example, the high-frequency strong electromagnetic field in the substation generates strong interference in the sensor device and the bonding wire, causing local strong induced current and parasitic capacitance and inductance in the sensor device. Under the protection of the shielding body, such influences are effectively isolated.

[0031] The present invention adopts a method of partially increasing the shielding structure. The solution has a simple manufacturing process, high cost performance, and is suitable for mass production, overcoming the problems of complex manufacturing processes and high costs of other packaging forms. The shielding structure in this solution uses metal and 3D printing resin, which is low in cost compared to high-end ceramic packaging and Kovar shell packaging, simple to manufacture, light in weight, and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference according to Embodiment 1 of the present invention;

[0033] Figure 2 This is a schematic structural diagram of a sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference according to Embodiment 2 of the present invention;

[0034] Figure 3 This is a schematic structural diagram of a sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference according to Embodiment 3 of the present invention;

[0035] Figure 4 This is a schematic structural diagram of a shielding body suitable for a wide temperature range and resistant to strong electromagnetic interference according to Example 11 of the present invention;

[0036] Figure 5 A schematic diagram of the structure of a sensor device packaging structure of a comparative example;

[0037] Figure 6 is a stress distribution diagram of a sensor device packaging structure of a comparative example at high temperature;

[0038] Figure 7 This is a deformation distribution diagram of the sensor device packaging structure of the comparative example at high temperature.

[0039] Among them, 1. sensor device; 2. bonding wire; 3. shielding body; 31. inner layer; 32. middle layer; 33. outer layer; 4. plastic package; 5. lead frame; 6. through hole. DETAILED DESCRIPTION

[0040] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown, so that the disclosure fully conveys the scope of the present invention to those skilled in the art. However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0041] The shielding principle of electromagnetic shielding materials is mainly based on the following three mechanisms: reflection, absorption and multiple reflection. For metal electromagnetic shielding materials, there are a large number of free electrons inside. When electromagnetic waves are irradiated to the metal surface, the collective vibration of a large number of free electrons produces a strong reflection effect. Therefore, the shielding structure contains metal materials, which will have a reflection effect on electromagnetic waves. At the same time, the impedance mismatch of electromagnetic waves at the interface of shielding materials and plastic packaging materials will also reflect electromagnetic waves. The absorption principle of electromagnetic shielding materials mainly includes magnetic loss absorption and electrical loss absorption. Under the action of an alternating magnetic field, the magnetic domains inside the material (such as ferrite) continuously rotate and flip, generating hysteresis loss and eddy current loss. Hysteresis loss is due to the alternating magnetic field inducing eddy currents inside the ferrite, and the eddy currents generate Joule heat on the ferrite resistor. These loss mechanisms enable ferrite to effectively absorb the energy of electromagnetic waves, thereby achieving the purpose of shielding electromagnetic interference. Electrical loss refers to the conduction current generated by the free electrons inside the conductive material (such as metals and conductive polymers) under the action of an alternating electric field when electromagnetic waves are incident. When the conduction current flows inside the material, heat is generated due to the resistance of the material. The mechanism of multiple reflections is that when electromagnetic waves enter the material inside a shielding material with a certain thickness, some of the electromagnetic waves will be reflected multiple times between different interfaces inside the material. For example, in a multi-layer composite electromagnetic shielding structure, the electromagnetic wave may first penetrate the outer metal layer and enter the middle absorption layer. Inside the absorption layer, the electromagnetic wave will be reflected multiple times between interfaces. This multiple reflection mechanism plays an important role in improving the shielding effectiveness in a multi-layer electromagnetic shielding structure.

[0042] When electromagnetic waves are incident on the shield, reflection, refraction and absorption will occur on the surface of the shield. If the shape of the shield is not designed properly, multiple reflections and interferences may occur when the electromagnetic waves propagate inside the shield, thus forming local electromagnetic oscillation enhancement points. These enhancement points will increase the local electromagnetic field intensity, which may break through the shielding effectiveness of the shield, causing the sensor device and the bonding wire to be subjected to stronger electromagnetic interference, affecting the normal operation of the sensor. From the perspective of electromagnetic theory, electromagnetic waves will produce different scattering modes under boundary conditions of different shapes. For example, at sharp corners or irregular shapes, electromagnetic waves are prone to focusing effects, resulting in the concentration of electromagnetic field energy and the formation of electromagnetic oscillation enhancement areas. In addition, the interlayers, gaps or interfaces between different materials inside the shield may also cause reflection and interference of electromagnetic waves, resulting in local oscillation enhancement. Therefore, compared with traditional structures, flexible and changeable shield structures are more effective in adaptively modifying the sensor device packaging structure according to the actual electromagnetic environment, thereby more effectively avoiding local electromagnetic oscillation phenomena.

[0043] In addition, under different power usage environments, different types of electromagnetic waves may cause oscillation enhancement inside the device. At this time, adjusting the shape of the shield can optimize the electromagnetic environment and avoid such local oscillation enhancement.

[0044] Example 1

[0045] Figure 1 The structural schematic diagram of an embodiment 1 of the present invention is shown, including a sensor device 1, a bonding wire 2, a shielding body 3, a plastic package 4, and a lead frame 5. The shielding body 3 is located outside the sensor device 1 and the bonding wire 2, and is fixed to the lead frame 5 by a thermosetting adhesive. The use of thermosetting adhesive here can prevent the shielding body 3 from being connected to the lead frame 5, thereby achieving an insulating effect. The shielding body 3 is made of an anti-electromagnetic shielding material. In this embodiment, the anti-electromagnetic shielding material is copper, and the bonding wire 2 is a round wire made of gold, one end of which is welded to the sensor device 1 and the other end is welded to the lead frame 5. The plastic package 4 material is an epoxy plastic package, which is coated on the outside of the shielding body 3 and is in close contact with the lead frame 5, isolating the sensor device 1, the bonding wire 2, and the shielding body 3 from contact with the external environment. The chamber formed by the shielding body 3 here isolates the contact between the plastic package 4 material and the bonding wire 2 and the sensor device 1 material. The sensor device 1 here is a power sensor sensor device, and the lead frame 5 is a copper alloy lead frame.

[0046] The working principle and beneficial effects of the above technical solution are as follows: copper has extremely high electrical conductivity and is a good conductive material that effectively reflects electromagnetic waves. In a changing magnetic field, copper materials will generate eddy currents, but due to their good electrical conductivity, eddy current losses are relatively small, which makes copper perform well in shielding high-frequency magnetic fields. In addition, the copper shield isolates the direct contact between the plastic encapsulation material and the bonding wires and sensor components. When the external temperature changes, the thermal expansion of the plastic encapsulation material will not cause stress and strain in the bonding wires and sensor components, especially will not generate a large tensile force on the bonding wires, thereby improving the reliability of the bonding wires and sensor components.

[0047] Example 2

[0048] Figure 2The structural schematic diagram of a specific embodiment 2 of the present invention is shown, including a sensor device 1, a bonding wire 2, a shielding body 3, a plastic package 4, and a lead frame 5. The shielding body 3 is located outside the sensor device 1 and the bonding wire 2, and is fixed to the lead frame 5 by ultraviolet curing glue. The shielding body 3 is made of 3D printing resin, the outer layer is wrapped with conductive rubber, and the conductive rubber is filled with nickel-coated copper powder. The bonding wire 2 is a round wire made of gold, one end of which is press-welded to the sensor device 1, and the other end is press-welded to the lead frame 5. The plastic package 4 is made of epoxy plastic package material, which is coated on the outside of the shielding body 3 and is in close contact with the lead frame 5, isolating the sensor device 1, the bonding wire 2, and the shielding body 3 from contact with the external environment. The chamber formed by the shielding body 3 here isolates the contact between the plastic package 4 material and the bonding wire 2 and the sensor device 1 material. The sensor device 1 here is a power sensor sensor device, and the lead frame 5 is a copper alloy lead frame.

[0049] The working principle and beneficial effects of the above technical solution are as follows: the shielding material is 3D printing resin, and a special-shaped structure can be made according to the internal structure of the sensor. It is lightweight and can be fixed on the lead frame by UV curing glue. The use of UV curing glue here can prevent the shielding body from being connected to the lead frame, thus achieving an insulating effect. The nickel-clad copper conductive rubber for external shielding has excellent electromagnetic shielding performance and is cost-effective. It can electromagnetically shield the sensor components and bonding wires inside the device. At the same time, the resin material also has the effect of isolating the contact between the sensor components and bonding wires and the plastic package, thus avoiding stress and deformation.

[0050] Example 3

[0051] Figure 3 The structural schematic diagram of a specific embodiment 3 of the present invention is shown, including a sensor device 1, a bonding wire 2, a shielding body 3, a plastic package 4, and a lead frame 5. The shielding body 3 is located outside the sensor device 1 and the bonding wire 2, and is fixed to the lead frame 5 by ultraviolet curing glue. The shielding body 3 has an interlayer filled with ferrite powder, and the interlayer of the shielding body 3 is provided with a through hole 6. The shielding body 3 is made of 3D printing resin. The bonding wire 2 is a round wire made of gold, one end of which is press-welded to the sensor device 1, and the other end is press-welded to the lead frame 5. The plastic package 4 is made of epoxy plastic package, which is coated on the outside of the shielding body 3 and is in close contact with the lead frame 5, isolating the sensor device 1, the bonding wire 2, and the shielding body 3 from contact with the external environment. The chamber formed by the shielding body 3 here isolates the contact between the plastic package 4 material and the bonding wire 2 and the sensor device 1 material. The sensor device 1 here is a power sensor sensor device, and the lead frame 5 is a copper alloy lead frame.

[0052] The working principle and beneficial effects of the above technical solution are as follows: the shielding body 3 is made of 3D printed resin, which can form a sandwich in the middle and is provided with a filling port to fill the electromagnetic shielding material to electromagnetically shield the internal sensor device. In this way, more types of electromagnetic shielding materials can be used. The ferrite material used here has a high magnetic permeability and is better than high-conductivity materials for low-frequency electromagnetic shielding. The shielding body can be fixed to the lead frame by UV curing glue. The use of UV curing glue here can prevent the shielding body from being connected to the lead frame, thereby achieving an insulating effect. The resin material also has the effect of isolating the contact between the sensor device and the bonding wire and the plastic package, thereby avoiding stress and deformation.

[0053] Example 4

[0054] Specific embodiment 4 of the present invention is based on specific embodiment 1, and further, the material of the shielding body 3 is aluminum, which has good conductivity, has the effect of reflecting and multiple reflections on electromagnetic waves, and has a certain absorption effect. It is light in weight, easy to process, has good plasticity and machinability, and can be made into shielding parts of various shapes and sizes through various processing methods such as extrusion, stretching, stamping, casting, etc., and has low cost.

[0055] Example 5

[0056] Specific embodiment 5 of the present invention is based on specific embodiment 1, and further, the material of the shielding body 3 is ferrite. Ferrite material has high magnetic permeability, can effectively guide and bind the magnetic field, has a keen response to the change of the magnetic field, and reduces the interference of the magnetic field on the surrounding environment. Due to the resonance absorption of ferrite materials and the dispersion effect of magnetic permeability, ferrite has a strong absorption capacity for electromagnetic waves, strong absorption and wide bandwidth. Ferrite is easy to process and can be processed into shielding components of various shapes and sizes through various processes such as pressing, sintering, and injection molding. The cost is low, which enables it to effectively reduce costs when used on a large scale.

[0057] Example 6

[0058] Specific embodiment 6 of the present invention is based on specific embodiment 2, and further, the material coated on the outside of the shielding body 3 is a mixed polymer of copper powder and ferrite powder. Copper has a significant shielding effect in the high frequency band, and ferrite performs well in the low frequency band. Combining the two can achieve broadband electromagnetic shielding from low frequency to high frequency. The structure in specific embodiment 2 of the present invention can mix two or more powders, and can effectively and flexibly adjust the electromagnetic shielding performance of the shielding body.

[0059] Example 7

[0060] Specific embodiment 7 of the present invention is based on specific embodiment 3. Further, the electromagnetic shielding material in the interlayer can be a mixed powder of copper powder and ferrite powder. Copper has a significant shielding effect in the high frequency band, and ferrite performs well in the low frequency band. Combining the two can achieve broadband electromagnetic shielding from low frequency to high frequency. The structure in specific embodiment 3 of the present invention can mix two or more powders, which can effectively and flexibly adjust the electromagnetic shielding performance of the shielding body.

[0061] Example 8

[0062] Specific embodiment 8 of the present invention is based on specific embodiment 2, further, the material coated on the outside of the shielding body 3 is a carbon black mixed polymer, and the carbon black raw material is widely available and has a low production cost. The carbon black particles can be dispersed more evenly in the matrix material, which helps to form a continuous conductive network, thereby improving the electromagnetic shielding effect. Good dispersibility allows carbon black to be compounded with a variety of materials, such as plastics, rubbers, coatings, etc., expanding its application range. Carbon black is highly adjustable. By changing parameters such as the particle size, structure, and surface properties of carbon black, its conductive properties and electromagnetic shielding properties can be adjusted to meet the needs of different application scenarios.

[0063] Example 9

[0064] Specific embodiment 9 of the present invention is based on specific embodiment 2, and further, the material coated on the outside of the shielding body 3 is a polymer filled with silver powder. Silver has the best conductivity among all metals, which means that it can quickly conduct current and quickly form an induced current on the surface of the material, thereby generating a reverse electromagnetic field, effectively offsetting the incident electromagnetic waves, and achieving efficient shielding of electromagnetic radiation. Good conductivity enables it to have a good shielding effect on electromagnetic waves of different frequencies, whether it is a high-frequency radio frequency signal or a low-frequency electromagnetic field. Silver can play an effective blocking role and is suitable for various complex electromagnetic environments. Silver has a high reflectivity to electromagnetic waves and can reflect most of the electromagnetic waves back, reducing the penetration of electromagnetic waves. The silver material is wrapped in the plastic package 4, which effectively isolates the contact between silver and air, avoids the oxidation of silver, and affects the performance.

[0065] Example 10

[0066] Specific embodiment 10 of the present invention is based on specific embodiment 3, further, the electromagnetic shielding material in the interlayer is silver powder, and silver has the best conductivity among all metals, which means that it can quickly conduct current, can quickly form an induced current on the surface of the material, and then generate a reverse electromagnetic field, effectively offset the incident electromagnetic waves, and achieve efficient shielding of electromagnetic radiation. Good conductivity enables it to have a good shielding effect on electromagnetic waves of different frequencies, whether it is a high-frequency radio frequency signal or a low-frequency electromagnetic field. Silver can play an effective blocking role and is suitable for various complex electromagnetic environments. Silver has a high reflectivity to electromagnetic waves, and can reflect most of the electromagnetic waves back, reducing the penetration of electromagnetic waves. Silver is filled in the interlayer, and the interlayer filling port is closed by the plastic sealing body 4, which effectively isolates the contact between silver and air, avoids the oxidation of silver, and affects the performance.

[0067] Embodiment 11

[0068] Specific embodiment 11 of the present invention is based on specific embodiment 3, and further, a multi-layer electromagnetic shielding structure is set, and different electromagnetic shielding materials are filled respectively, and the electromagnetic parameters gradually change, so as to achieve smoother impedance matching and more effective absorption of electromagnetic waves. Specifically, a three-layer shielding structure is set, such as Figure 4 As shown, from the inside to the outside, there are the inner layer 31, the middle layer 32 and the outer layer 33. Each interlayer is nested layer by layer, and is respectively combined with the lead frame 5 to form a closed shielding cavity to accommodate the protection sensor device and the bonding wire. The inner layer is close to the sensor device, and a ferrite material with high magnetic permeability can be used, which can effectively guide and bind the magnetic field, and has a good absorption and shielding effect on low-frequency electromagnetic waves; the middle layer adopts a transition material, such as a composite material of nickel-zinc ferrite and conductive polymer, whose electromagnetic parameters are between the inner layer and the outer layer, and plays a role in transition and adjusting impedance matching; the outer layer uses a metal material with high electrical conductivity (such as copper or aluminum), which is mainly used to reflect high-frequency electromagnetic waves and prevent the entry of external electromagnetic waves. In another embodiment, the shielding body is provided on both sides of the lead frame 5, and the interlayers contained in the shielding bodies on both sides can use the same number of layers and fillers, or use different numbers of interlayers and fillers to achieve better shielding effect or differentiated shielding effect.

[0069] Comparative Example

[0070] The sensor device packaging structure of the comparative example is the same as that of the embodiment 1, except that it does not contain the shielding body 3. Figure 5 As shown, the plastic package 4 is in direct contact with the sensor device 1 and the bonding wire 2 .

[0071] Perform stress analysis on the sensor device packaging structure provided by the comparative example: Assume that the sensor is at a local high temperature point in the environment, the ambient temperature is as high as 70°C, and set the heat transfer coefficient of ordinary air convection to simulate heat transfer. Simulate and calculate the thermal expansion stress and deformation of the sensor under this temperature condition. Import the temperature results obtained by thermal analysis into the structural analysis module, and calculate the thermal expansion stress and deformation according to the material properties and geometric constraints.

[0072] The results are as follows Figure 6 , Figure 7 As shown. Among them, Figure 6 is a stress distribution diagram of a sensor device packaging structure of a comparative example at high temperature; Figure 7 This is a deformation distribution diagram of the sensor device packaging structure of the comparative example at high temperature.

[0073] Figure 6 : Stress distribution

[0074] Static Structural: Static structural analysis

[0075] Equivalent Stress: Equivalent Stress

[0076] Equivalent (von-Mises) Stress: Equivalent stress

[0077] Unit:MPa: Unit: MPa

[0078] Max:1519.6: Maximum value:1519.6

[0079] Min:0.14845: Minimum value: 0.14845

[0080] Figure 7 :Deformation

[0081] Static Structural: Static structural analysis

[0082] Total Deformation: Total deformation (unit: mm)

[0083] Type:Total Deformation: Type:Total Deformation

[0084] The chart is generated in finite element analysis software to analyze the stress distribution and deformation of a structure under load. The color gradient in the figure represents the stress magnitude or deformation degree at different locations. Red represents the area with the maximum value, while blue or green represents the area with the minimum value.

[0085] like Figure 6As shown, the stress in most areas is below 50MPa, and the stress caused by thermal expansion mismatch is effectively dispersed in these areas, so that the stress is kept at a low level. A large concentrated stress greater than 500MPa appears at the bonding point between the bonding wire and the sensor device. The geometric shape here changes suddenly, the contact area is narrow, and the thermal expansion coefficients of the plastic package 4, bonding wire 2, and sensor device 1 are quite different, which leads to stress concentration at this location. In addition, a large stress of 200MPa to 300MPa also appears at the solder, and the large difference in thermal expansion coefficients between the solder and the sensor device leads to stress concentration.

[0086] Long-term or frequent exposure to high stress can easily cause fatigue damage to the material, and cracks will gradually appear and expand inside, gradually weakening the reliability of the connection. High stress can also affect the contact characteristics between the bonding wire and the sensor device, leading to electrical performance problems such as increased resistance and reduced signal transmission quality.

[0087] The stress distribution in the sensor, especially the large stress at the bonding point between the bonding wire 2 and the sensor device 1 and at the solder, needs to be further evaluated for its impact on the long-term reliability and performance of the sensor, and corresponding optimization measures should be taken to reduce the stress level or improve the load-bearing capacity of these key parts.

[0088] like Figure 7 As shown, the sensor deformation mainly occurs in the central area of ​​the plastic package 4 and the bonding line 2, the maximum deformation can reach 12.8um, and the deformation of the sensor device area is between 7um and 10um.

[0089] The thermal expansion coefficient of epoxy resin molding compound is usually (10-60)×10 -6 / ℃ range. This value is affected by many factors, such as the formula of epoxy resin, the type of curing agent, the type and content of filler, etc. The thermal expansion coefficient of gold wire is about 14.2×10 -6 / ℃. The thermal expansion coefficient of silicon is relatively low, about 2.5×10 -6 / ℃. The epoxy resin molding compound deforms when it is heated and expanded. The gold wire is soft and is affected by the expansion and deformation of the molding compound, generating stress and strain. According to the simulation results, the stress and strain at the welding point between the gold wire and the sensor device is large. The thermal expansion coefficient of silicon is quite different from that of the epoxy resin molding compound. When the temperature changes, the thermal expansion mismatch between the two causes stress and strain in the sensor device, affecting the performance of the sensor device.

[0090] Since the elastic modulus of the plastic package 4 is low and the thermal expansion coefficient is large, it is more likely to deform under stress. The bonding wire 2 is slender and soft, and its ability to resist stretching and bending is relatively weak, and it is easy to produce large deformation under stress. The interaction between the sensor device 1 and the surrounding plastic package 4, bonding wire 2 and other components affects the degree and distribution of its deformation. The difference in thermal expansion between the sensor device 1, the plastic package 4 and the solder will produce mutual restraint when the temperature changes, resulting in a certain degree of deformation, affecting the performance of the sensor device. In short, the deformation distribution of the sensor is determined by multiple factors such as material properties, structural design, stress conditions, and the interaction between components.

[0091] The present invention aims at the problems of reliability and anti-interference of the current plastic-encapsulated sensor device package in the power environment, and makes structural improvements based on the existing technology. After the shielding body 3 is added, the bonding wire 2 and the sensor device 1 are completely isolated from the plastic encapsulation body 4. In this way, the deformation of the plastic encapsulation body 4 due to thermal expansion or moisture absorption will not have any effect on the bonding wire 2 and the sensor device 1 inside the shielding body 3. Accordingly, no additional stress caused by temperature changes will appear in this part. Figure 1 As shown, in the comparative example, the plastic package 4 is in full contact with the bonding wire 2 and the sensor device 1; Figure 2 In Example 1, the plastic package 4 is completely isolated from the bonding wires 2 and the sensor device 1, so no additional stress is applied.

[0092] In addition, the sensor device packaging structure provided by the present invention, which is suitable for a wide temperature range and resistant to strong electromagnetic interference, also has the following advantages:

[0093] 1. A multifunctional shielding structure is designed. This multifunctional shielding structure has the ability to resist external electromagnetic interference. In a complex power electromagnetic environment, the anti-interference ability of sensor devices is improved. Not only that, it also constructs an isolation layer between the plastic package and the bonding wire. During the operation of the power system, environmental factors have a huge impact on sensor devices. For example, changes in temperature can cause the plastic package to expand and contract, and changes in humidity may also cause the plastic package to deform after absorbing moisture. The stress and strain generated by these deformations will damage the bonding wires and devices, seriously affecting the performance and service life of the sensor device. The existing plastic package packaging structure has problems such as no electromagnetic shielding function and direct contact between the plastic package and the bonding wire. The multifunctional shielding structure in the present invention can effectively avoid these problems, ensure the reliability of the sensor device in the wide temperature range environment and some humid environments of the power system, and ensure that it can work stably and accurately.

[0094] 2. A special electromagnetic shielding structure is innovatively designed, and this structure is processed by 3D printing. 3D printing technology gives the structure a high degree of accuracy and a complex and customizable internal structure. A sandwich is set inside it to fill various electromagnetic shielding materials. In the power system, different application scenarios face electromagnetic shocks of different intensities and types, and the electromagnetic shock parameters vary. The existing plastic package packaging form is not specifically designed for the power system environment, and it is inevitable to encounter various new problems when used in the power system. This special structural design makes it possible to flexibly adjust the type and ratio of electromagnetic shielding materials according to actual conditions. Whether it is to deal with strong electromagnetic interference near the substation or the relatively weak but complex electromagnetic environment in the distribution room, the shielding scheme can be adjusted in a targeted manner, which has the advantages of economy and practicality while ensuring the electromagnetic shielding effect, and reduces costs.

[0095] 3. A low-cost sensor packaging modification scheme has been designed. This scheme is a modification of the existing plastic package based on full consideration of cost-effectiveness and performance optimization. Effective cost control is achieved while improving the function of the sensor. Compared with other high-end packaging forms, such as ceramic packaging and metal packaging, the cost is greatly reduced. It makes large-scale applications possible and has a very high cost-effectiveness.

[0096] The benefits brought by the present invention to the power system are embodied in the following aspects:

[0097] 1. Improving the reliability of power system operation

[0098] In the complex electromagnetic environment of the power system, traditional sensor devices are susceptible to strong electromagnetic interference, resulting in signal distortion, increased measurement errors, and even equipment failure. This packaging structure has excellent resistance to strong electromagnetic interference, which can ensure that the sensor device works stably in a high electromagnetic interference environment and effectively reduce the probability of sensor failure caused by electromagnetic interference. This enables protection devices and monitoring systems in the power system that rely on sensor measurement data to accurately obtain information and reduce false operations, thereby significantly improving the reliability of the overall operation of the power system and ensuring the continuity of power supply.

[0099] (II) Expanding the operating temperature range and enhancing adaptability

[0100] The working environment temperature of the power system varies greatly, ranging from extremely cold to extremely hot conditions. This packaging structure is suitable for a wide temperature range, breaking through the limitation of the traditional sensor packaging structure that the performance of the sensor component degrades at low or high temperatures. It ensures that the power system can effectively monitor key parameters (such as temperature, current, voltage, etc.) within a wide temperature range, reduces the risk of sensor failure caused by temperature changes, extends the service life of the sensor, and reduces maintenance costs and replacement frequency.

[0101] (III) Reduce maintenance costs and improve economic benefits

[0102] Because the packaging structure improves the stability and durability of the sensor in harsh environments, it reduces the number of fault repairs caused by electromagnetic interference and temperature changes. At the same time, it reduces the downtime of the power system caused by sensor failure, improves the efficiency of power production and transmission, and indirectly brings considerable economic benefits to power companies. In addition, in the deployment of large-scale power systems, this stable and reliable sensor helps to optimize the system operation status, avoid energy waste caused by inaccurate sensor data, and further save costs.

[0103] (IV) Ensuring the safety and stability of the power system

[0104] In terms of power system safety protection, accurate sensor data is crucial for timely detection of potential fault hazards. This packaging structure ensures that the sensor device works normally in a wide temperature range and strong electromagnetic interference environment, and can timely and accurately feedback the operating status of power equipment, such as transformer oil temperature, winding temperature, contact status of switchgear, etc. This helps to warn of possible safety accidents in advance, such as overheating, short circuit, etc., so that maintenance personnel have enough time to take measures to avoid the expansion of accidents, ensure the safe and stable operation of the power system, and reduce the economic losses and social impact caused by power accidents.

[0105] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A shielding body suitable for a wide temperature range and resistant to strong electromagnetic interference, characterized in that: The shielding body has a shielding cavity for accommodating the sensor device; and the shielding body contains anti-electromagnetic interference material.

2. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 1 is characterized in that: The shielding body is made of the anti-electromagnetic interference material.

3. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 1 is characterized in that: The surface of the shielding body is coated with the anti-electromagnetic interference material.

4. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 1, characterized in that: The shielding body has an interlayer, and the interlayer is filled with the anti-electromagnetic interference material.

5. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 4 is characterized in that: There are multiple interlayers, each of which is filled with different anti-electromagnetic interference materials.

6. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 4, characterized in that: The shielding body is provided with a through hole for filling with anti-electromagnetic interference material.

7. The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 3 or 4, characterized in that: The main body of the shield is made of 3D printing resin.

8. A sensor device packaging structure suitable for a wide temperature range and resistant to strong electromagnetic interference, characterized in that: The shielding body applicable to a wide temperature range and resistant to strong electromagnetic interference as claimed in claim 1, wherein the packaging structure comprises: Lead frame (5); A sensor device (1) fixed to the lead frame (5) and realizing external electrical connection through the lead frame (5); A shielding body (3) fixed to the lead frame (5) and forming a shielding cavity for accommodating the sensor device (1); The plastic sealing body (4) covers the outer side of the shielding body (3).

9. The sensor device packaging structure applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 8, characterized in that: Also comprising a bonding wire (2); One end of the bonding wire (2) is connected to the sensor device (1), and the other end is connected to the lead frame (5), thereby realizing electrical connection between the sensor device (1) and the lead frame (5).

10. The sensor device packaging structure applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 9, characterized in that: The bonding wire (2) is located in a shielding cavity formed by the shielding body (3) and the lead frame (5).

11. The sensor device packaging structure applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 8, characterized in that: The shielding body (3) is fixed on the lead frame (5) by means of insulating glue.

12. The sensor device packaging structure applicable to a wide temperature range and resistant to strong electromagnetic interference according to claim 9, characterized in that: The bonding wire (2) is connected to the sensor device (1) and the lead frame (5) by welding.

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