A sensor and electrical connector packaging process

Abstract

The application discloses a sensor and an electric connector packaging process, comprising the following steps: a sealing groove is formed on the shell of the sensor, a through hole is formed at the bottom of the sealing groove, the sensor and the electric connector are pre-assembled through the through hole to prevent the debonding failure of the sealing material and the sealing groove connection interface under low temperature stress, and the un-solidified sealing material is filled into the sealing groove, and a pressing part is installed on the sealing material; a constant pre-tightening force is applied to the pressing part; then, the sealing material is subjected to programmed temperature cycling, including a first solidification stage and a second solidification stage, so that a cross-linking network is formed in the sealing material, and then the cross-linking network is shaped to complete the packaging of the sensor and the electric connector, thereby enhancing the bonding capacity and anti-debonding capacity of the sealing material under thermal stress, reducing the risk of cracking and leakage of the packaging structure under an extreme low-temperature environment, and ensuring that the packaging structure has excellent sealing performance and application reliability under the extreme low-temperature environment.

Description

Technical Field

[0001] This application relates to the field of sensor packaging technology, and in particular to a packaging process for a sensor and an electrical connector. Background Technology

[0002] With the rapid development of electronic devices towards miniaturization, high integration, and high power, their applications in extreme low-temperature environments such as high altitudes, polar regions, and space exploration are becoming increasingly widespread. Various sensors and electronic systems often need to operate stably at extreme temperatures of -60°C or even lower. As a critical interface for signal and energy transmission, the sealing integrity and electrical contact stability of electrical connectors at low temperatures directly determine the success or failure of the entire system. However, due to the inherent differences in the coefficients of thermal expansion between the metals, insulators, and sealing materials in the encapsulation structure formed by the sensor and electrical connector, significant thermal mismatch stresses can occur in extreme low-temperature environments. This leads to cracking and leakage at the sealing interface and causes a significant drift in the contact resistance of the pins, reducing the reliability of the sensor in extreme low-temperature applications.

[0003] In the prior art, the following methods are commonly used to improve the reliability of sensors in low-temperature environments: (1) using sealing materials with low shrinkage and high elasticity or using hard sealing methods such as low melting point glass and solder; (2) introducing passive components such as springs and buffer layers in the structural design to absorb deformation. However, the cost of material modification in these methods is high and the performance improvement is limited. Moreover, the design of passive structures increases the volume and complexity of the overall packaging structure. Summary of the Invention

[0004] This application aims to at least address one of the aforementioned technical problems existing in the prior art. Therefore, the purpose of this application is to provide a sensor and electrical connector packaging process to improve the reliability of existing sensors and electrical connectors in extreme low-temperature environments.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: A packaging process for a sensor and an electrical connector includes: A sealing groove is formed on the housing of the sensor, and the sealing groove is pre-treated; The sensor is pre-assembled with the electrical connector, and uncured sealing material is filled into the sealing groove. A clamping element is then installed on the sealing material. A constant preload is applied to the clamping member, which transmits the preload to the sealing material so that the sealing material fits into the sealing groove. The sealing material is heated to enter the first curing stage, which initially forms a cross-linked network inside the sealing material. Then, the sealing material is cooled to enter the second curing stage, where the initially formed cross-linked network is shaped to complete the encapsulation of the sensor and the electrical connector.

[0006] According to some embodiments of this application, heating the sealing material to enter a first curing stage, thereby initially forming a cross-linked network within the sealing material, includes: The sealing material is heated to a first temperature, which is higher than the phase transition temperature of the sealing material, so that the sealing material is in a liquid state; At the same time, the clamping element converts the pre-tightening force into pressure acting on the sealing material, causing the sealing material to initially form a cross-linked network, so that the sealing material has the ability to maintain its shape.

[0007] According to some embodiments of this application, the subsequent cooling of the sealing material to enter the second curing stage, and the shaping of the initially formed cross-linked network, includes: The sealing material is cooled to a second temperature at a preset cooling rate. The second temperature is lower than the phase transition temperature of the sealing material, causing the sealing material to change from a liquid state to a solid state. During the cooling process, pressure is continuously applied to the sealing material by the clamping component, causing the initially formed cross-linked network to extend in the direction that counteracts the preset low-temperature shrinkage, so as to construct a stress compensation structure in the sealing material; After the sealing material has completely solidified, it is kept at the second temperature for a preset time to shape the stress compensation structure.

[0008] According to some embodiments of this application, the preload force and the cooling rate are related to the phase change temperature T of the sealing material. p Mutual matching includes: When T p When the temperature is below -60℃, the preload force ranges from 5.0MPa to 6.0MPa, and the cooling rate ranges from 0.2℃ / min to 0.5℃ / min. When -60℃≤T p When the temperature is less than -50℃, the preload force ranges from 4.0MPa to 5.0MPa, and the cooling rate ranges from 0.5℃ / min to 0.8℃ / min. When -50℃≤T p When the temperature is below -40℃, the preload force ranges from 3.0MPa to 4.0MPa, and the cooling rate ranges from 0.8℃ / min to 1.2℃ / min. When T pWhen the temperature is ≥-40℃, the value of the preload is in the range of 1.0MPa~3.0MPa, and the value of the cooling rate is in the range of 1.2℃ / min~1.5℃ / min.

[0009] According to some embodiments of this application, the temperature change range during the cooling process includes the phase change window period of the sealing material. The phase change window period is the temperature range in which the energy storage modulus of the sealing material decreases to below 50% of its initial value during the cooling process, and the loss factor of the sealing material reaches its peak value.

[0010] According to some embodiments of this application, the time t during the phase change window period in the cooling process is determined by the phase change temperature T of the sealing material. p Decide, When T p At -60℃, 90min < t < min; When -60℃≤T p At ≤-50℃, 60min<t<90min; When T p At -50℃, 30min < t ≤ 60min.

[0011] According to some embodiments of this application, a sealing groove is formed on the housing of the sensor, and the sealing groove is pre-treated, including: The sealing groove is physically roughened to reduce its surface roughness R. a The value range is 3.2μm to 12.5μm; The sealing groove is chemically activated to form a chemical transition layer on its surface, the thickness of which ranges from 10. ~50 .

[0012] According to some embodiments of this application, the electrical connector includes a pin assembly, and the bottom of the sealing groove has a through hole. The process of pre-assembling the sensor with the electrical connector, filling the sealing groove with uncured sealing material, and installing a clamping member on the sealing material includes: One end of the pin assembly passes through the through hole and is connected to the interior of the sensor, while the other end of the pin assembly is connected to the electrical connector; Uncured sealing material is injected into the sealing groove using a precision dispensing device, and the liquid level of the sealing material in the sealing groove is lower than the top of the portion of the pin assembly located in the sealing groove that is not covered by the sealing material, the top being the end face of the pin assembly near the electrical connector. The clamping element is fitted onto the outer periphery of the pin assembly and pressed against the upper surface of the sealing material.

[0013] According to some embodiments of this application, the packaging process further includes: Remove the clamping element; Electrical continuity and sealing tests were performed on the structure after the sensor and electrical connector were packaged.

[0014] According to some embodiments of this application, the electrical continuity test and sealing test performed on the packaged structure of the sensor and electrical connector include: At the test temperature T test Under conditions of ≤-60℃, the encapsulated structure is subjected to an electrical continuity test for a test time of ≥100h; The encapsulated structure was subjected to helium mass spectrometry leak detection at room temperature. The encapsulated structure was subjected to a low-temperature vacuum pressure decay test within a vacuum chamber.

[0015] The beneficial effects of this application are: This application pre-treats the sealing groove to prevent debonding failure of the sealing material at the sealing groove interface under low-temperature stress. Then, a pre-tightening force is applied to the sealing material, ensuring a tight fit between the sealing material and the sealing groove, as well as the gaps between the pin assembly and the through-hole. While maintaining a constant pre-tightening force, the sealing material undergoes programmed temperature cycling, causing a cross-linked network to form and solidify within the sealing material. This achieves the encapsulation of the sensor and electrical connector, enhancing the sealing material's bonding and anti-debonding capabilities under thermal stress. It also reduces the risk of cracking and leakage in the sensor and electrical connector encapsulation structure under extreme low-temperature environments, ensuring excellent sealing performance and application reliability in extreme low-temperature conditions.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a process flow diagram of the packaging process for a sensor and an electrical connector according to this application.

[0018] Figure 2 This is a schematic diagram of the sensor and the electrical connector connection.

[0019] Figure 3 This is a top view of the sensor housing.

[0020] Figure 4 This is a schematic diagram showing the correspondence between programmed temperature cycling and the phase transition window period of materials.

[0021] Figure label: 100. Outer shell; 110. Sealing groove; 120. Through hole; 200. Electrical connector; 210. Pin assembly; 300. Sealing materials. Detailed Implementation

[0022] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0023] In the description of this application, it should be understood that if directional descriptions are involved, such as up, down, front, back, left, right, etc., indicating the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings, it is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In the description of this application, if words such as several, greater than, less than, exceeding, above, below, or within appear, "several" means one or more, "more than" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, and "above," "below," "within," etc. are understood to include the number itself.

[0025] In the description of this application, the use of terms such as "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0026] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0027] Because the existing packaging structure between sensors and electrical connectors is prone to thermal mismatch stress in extreme low-temperature environments, and current technologies offer limited performance improvements and are costly, researchers have attempted to apply static prestress during the packaging process to partially offset service stress in order to improve the reliability of sensors in low-temperature applications. However, they subsequently discovered a problem: conventional prestressing methods fail to integrate with the thermo-mechanical state changes during the material curing process. The application of prestress is out of sync with the formation of the internal structure of the material, resulting in low stress compensation efficiency and an inability to accurately and directionally offset the specific shrinkage stress caused by deep cooling. Therefore, it is difficult to ensure the reliability of sensors and electrical connectors for long-term use in extreme low-temperature environments.

[0028] Therefore, it is necessary to further improve the reliability of the sensor and electrical connector packaging structure, referring to... Figures 1 to 4 The following are specific embodiments of this application.

[0029] Depend on Figures 1 to 4 As shown, this application provides a packaging process for a sensor and an electrical connector, including: S100, A sealing groove 110 is formed on the sensor housing 100, and the sealing groove 110 is pre-treated, including: S110. Physically roughen the sealing groove 110 to reduce the surface roughness R of the sealing groove 110. a The value range is 3.2μm to 12.5μm, including: sandblasting or laser treatment of the inner wall of the sealing groove 110 and the surrounding plane of the groove opening.

[0030] In some embodiments, when sandblasting is used, white corundum abrasive with a mesh size of 80-120 is selected, and the sealing groove 110 is uniformly treated under a pressure of 0.4MPa-0.6MPa. The Ra value is measured and controlled within the specified range using a stylus-type profilometer. When Ra < 3.2μm, the mechanical anchoring effect is insufficient; when Ra > 12.5μm, the peaks and valleys may be too deep, potentially forming stress concentration points or encapsulating air bubbles during subsequent filling and stress. Therefore, the surface roughness Ra is reduced. a The value range is set to 3.2μm to 12.5μm, which can ensure the contact area between the sealing material 300 and the metal surface of the sealing groove 110, providing a physical basis for the firm bond between the sealing material 300 and the sealing groove 110.

[0031] The sealing groove 110 is an annular groove.

[0032] Preferably, the outer casing 100 is made of aluminum alloy or stainless steel, and the surface roughness R of the sealing groove 110 is [missing information]. a It is 6.3 μm.

[0033] S120. The sealing groove 110 is chemically activated to form a chemical transition layer on the surface of the sealing groove 110. The thickness of the chemical transition layer is within the range of 10. ~50 .

[0034] In some embodiments, the shell 100, after undergoing physical roughening treatment, is immersed in an aqueous ethanol solution containing silane coupling agent (KH-550) at a concentration of 1wt% to 2wt%, wherein the volume ratio of ethanol to water is 95:5. After immersion for 2 to 5 minutes, the shell 100 is removed and dried at 110°C for 10 minutes, thereby forming a dense silane coupling agent film, i.e., a chemical transition layer, on the surface. The thickness of the silane coupling agent film is measured and controlled using an ellipsometry (not shown).

[0035] The principle of chemical transition layer formation is as follows: the methoxy group at one end of the KH-550 molecule hydrolyzes and condenses with the hydroxyl groups of the metal on the surface of the sealing groove 110, while the amino group at the other end can chemically react with the sealing material that is subsequently filled.

[0036] Physical roughening and chemical activation treatments are used to synergistically enhance the interfacial bonding ability between the sealing material and the metal surface of the sealing groove 110 during the phase change window. The two work together to form a composite interface structure that combines "micron-level mechanical interlocking" and "nano-level chemical bonding", which fundamentally enhances the surface of the sealing groove 110's resistance to peeling and shearing under extreme temperature changes.

[0037] S200, Pre-assembling the sensor and electrical connector 200, filling the sealing groove 110 with uncured sealing material 300, and installing a clamping member (not shown) on the sealing material 300, including: S210, the electrical connector includes a pin assembly 210. A through hole 120 is provided at the bottom of the sealing groove 110, and multiple through holes 120 are spaced apart along the circumferential direction of the sealing groove 110. One end of the pin assembly 210 passes through the through hole 120 and connects to the internal circuitry of the sensor, while the other end of the pin assembly 210 connects to the electrical connector 200. The pin assembly 210 acts as a conductive medium, transmitting electrical signals collected or generated internally by the sensor to the electrical connector 200, which then outputs the signals to an external system, thus achieving reliable data transmission.

[0038] Preferably, the number of pin assemblies 210 matches the number of through holes 120.

[0039] S220. Using a precision dispensing device (not shown), uncured sealing material is injected into the sealing groove 110, and the liquid level of the sealing material in the sealing groove 110 is lower than the top of the part of the pin assembly 210 located in the sealing groove 110 that is not covered by the sealing material, the top being the end face of the pin assembly 210 on the side near the electrical connector 200.

[0040] Furthermore, the sealing material 300 is selected with a clearly defined phase transition temperature T. p Commercially available low-temperature phase change sealants include epoxy-based sealants, silicone-based sealants, and polyurethane-based sealants. Among these, addition-cured liquid silicone rubber is preferred for silicone-based sealants.

[0041] The phase transition temperature T of the sealant in these systems p The values ​​can be obtained through differential scanning calorimetry calibration. At the same time, the sealant also has cross-linkable active functional groups, which enable the sealant to form a three-dimensional network structure by triggering a cross-linking reaction through external conditions such as heating or light when a phase change is detected. This gives the sealant a stable shape retention ability and reliable airtight performance.

[0042] The sealing material 300 forms a cross-linked network inside, which means that the polymer chains or particles in the colloid are connected to each other through chemical bonds (covalent bonds) or physical forces (hydrogen bonds, ionic bonds, etc.) to build a three-dimensional spatial network structure, so that the system changes from a flowing sol state to a gel state with elasticity and stability, and no longer dissolves or melts.

[0043] Preferably, the sealing material 300 is an epoxy resin-based phase change sealant.

[0044] S230. The clamping element is fitted onto the outer periphery of the pin assembly 210 and pressed against the upper surface of the sealing material 300.

[0045] Specifically, the clamping member has an opening, which allows the clamping member to be fitted around the top of the pin assembly 210 and pressed against the upper surface of the sealing material 300.

[0046] In some embodiments, the clamping member is an annular structure, and the side of the clamping member that is close to the sealing material 300 is provided with a groove or protrusion that mates with the pin assembly 210, so that the clamping member can cover the pin assembly 210 and press against the upper surface of the sealing material 300, and fit evenly against the upper surface of the sealing material 300.

[0047] S300. Apply a constant preload to the clamping member, and the clamping member transmits the preload to the sealing material 300 so that the sealing material 300 fits into the sealing groove 110.

[0048] Before the sealing material 300 undergoes a significant cross-linking reaction, an axial load is applied to the clamping component using a pneumatic or servo press-fitting fixture with pressure feedback and a closed-loop control system. This means pressure is applied to the clamping component in a direction perpendicular to its horizontal plane. The press-fitting fixture contains a force sensor that monitors the preload applied to the clamping component in real time. The clamping component converts the applied pressure into surface pressure acting on the surface of the sealing material 300. The sealing material 300 is subjected to a uniform pressure P0, ensuring that the sealing material 300 forms contact with the bottom and inner wall of the sealing groove 110. Tight fit, or microscopic zero-gap fit, establishes a controllable directional stress field within the sealing material 300. This ensures perfect fit between the sealing material 300 and the surface of the sealing groove 110, eliminating the risk of internal gas or liquid leakage due to microscopic gaps. Furthermore, it provides an indispensable mechanical adjustment means to guide the directional rearrangement of molecular chains within the sealing material during the phase transition window, thereby optimizing the stress distribution and molecular orientation within the sealing material 300 and improving the long-term reliability of the sensor and electrical connector package.

[0049] In some embodiments, the pressure P0 applied to the sealing material 300 ranges from 1.0 MPa to 6.0 MPa. A pressure of 1.0 MPa ensures that the pressure effectively eliminates microscopic air bubbles generated at the interface between the sealing material 300 and the sealing groove 110, and promotes that the sealing material 300 fully adheres to the sealing groove 110 and the connection gap between the pin assembly 210 and the through hole 120. A pressure of 6.0 MPa prevents damage to the pin assembly or excessive compression of the sealing material 300, which could cause it to be squeezed out of the sealing groove 110.

[0050] Preferably, for standard-sized electrical connectors, the preload is set to 3.0 MPa.

[0051] S400: The sealing material 300 is heated to enter the first curing stage, so that a cross-linked network is initially formed inside the sealing material 300. Then the sealing material 300 is cooled to enter the second curing stage, and the initially formed cross-linked network is shaped to complete the encapsulation of the sensor and electrical connector 200.

[0052] Specifically, the pressing fixture continuously applies a constant preload to the clamping component and controls the fluctuation of the preload during the entire phase change process of the sealing material 300 to not exceed ±2% of the set value, thereby ensuring that the interior of the sealing material 300 is always guided by a mechanical constraint field in the same definite direction during the first curing stage and the second curing stage.

[0053] The first curing stage, namely Figure 4The high-temperature initial curing stage: First, the sealing material 300 is heated to a first temperature, which is higher than the phase change temperature of the sealing material 300, so that the sealing material 300 is in a liquid state.

[0054] At the same time, the clamping component converts the pre-tightening force into pressure acting on the sealing material 300, causing the sealing material 300 to initially form a cross-linked network, so that the sealing material 300 has the ability to maintain its shape.

[0055] The value of the first temperature is determined by the curing characteristics of the sealing material 300. The range of the first temperature is 80℃ to 150℃. Preferably, the first temperature is 120℃, and the temperature is maintained at 120℃ for 30 minutes. This allows the sealing material 300 to fully fit with the sealing groove 110 and the pin assembly 210 and the through hole 120 at the connection gap. The active functional groups in the sealing material 300 undergo a full cross-linking reaction under heating conditions to form a three-dimensional network structure. This results in the initial formation of a cross-linked network inside the material and gives it a certain shape retention capability.

[0056] The second curing stage, namely Figure 4 The cooling and low-temperature holding stages are as follows: The sealing material 300 is cooled to a second temperature at a preset cooling rate. This second temperature is lower than the phase transition temperature of the sealing material 300, causing the sealing material 300 to change from a liquid to a solid state. During the cooling process, pressure is continuously applied to the sealing material 300 by a clamping element, causing the initially formed cross-linked network to extend in the direction that counteracts the preset low-temperature shrinkage, thereby constructing a stress-compensating structure in the sealing material 300.

[0057] In some embodiments, the preload and cooling rate are related to the phase transition temperature T of the sealing material 300. p Mutual matching includes: When T p When the temperature is below -60℃, the preload value ranges from 5.0MPa to 6.0MPa, and the cooling rate ranges from 0.2℃ / min to 0.5℃ / min.

[0058] When -60℃≤T p When the temperature is below -50℃, the preload value ranges from 4.0MPa to 5.0MPa, and the cooling rate ranges from 0.5℃ / min to 0.8℃ / min.

[0059] When -50℃≤T p At temperatures below -40℃, the preload ranges from 3.0MPa to 4.0MPa, and the cooling rate ranges from 0.8℃ / min to 1.2℃ / min.

[0060] When T pWhen the temperature is ≥-40℃, the preload value ranges from 1.0MPa to 3.0MPa, and the cooling rate ranges from 1.2℃ / min to 1.5℃ / min.

[0061] Preload, cooling rate and phase transition temperature T p The synergistic matching relationship between them was obtained by calibration using a Differential Scanning Calorimeter (DSC), due to different phase transition temperatures T p The sealing materials differ in phase transition enthalpy, modulus change range, and phase transition region width. Therefore, the magnitude of the preload and the duration of action (i.e., cooling rate) required for the cross-linking reaction and the formation of the stress compensation structure vary among sealing materials 300. By calibrating the synergistic matching relationship between phase transition temperature, cooling rate, and preload, the preload and cooling rate can be precisely controlled according to the phase transition characteristics of a specific sealing material 300. This allows for precise control of the deformation behavior of the sealing material 300 during the phase transition process, ensuring the reliable formation of the stress compensation structure and ultimately obtaining a stable encapsulation.

[0062] Phase transition temperature T p The characteristic temperature at which the sealing material 300 undergoes a liquid-solid phase transition is set to a second temperature below T. p A temperature of at least 10°C.

[0063] More importantly, the phase transition temperature T p These are intrinsic properties of sealing material 300, calibrated using a differential scanning calorimeter (DSC) at a heating rate of 10 °C / min. Among them, the phase transition temperature T... p The phase transition temperature T of a sealing material is determined by the zero-crossing point of the first derivative of the DSC endothermic peak, for example, by measuring the phase transition temperature T of the endothermic peak. p To ensure that the sealing material 300 can completely transform from a liquid to a solid state and to provide a stable environment for the final cross-linking reaction, the lowest temperature in the programmed temperature cycle, i.e. the second temperature, needs to be set to ≤-62℃. At the same time, a certain period of low temperature holding is required at this lowest temperature to promote the complete completion of the cross-linking reaction in a deep phase transition state. This permanently freezes the optimized rearranged molecular chain conformation and internal stress distribution in the sealing material 300, ultimately obtaining a structurally stable and reliable encapsulation structure.

[0064] In some embodiments, the temperature change range during the cooling process includes the phase transition window of the sealing material 300. Therefore, the cooling rate needs to be selected to cover the phase transition window throughout the entire second curing stage. The cooling rate directly determines how quickly the sealing material 300 traverses the phase transition window. If the cooling rate is too fast (>1.5℃ / min), the sealing material 300 will remain in the softening window (i.e., in a liquid state) for too short a time, and the molecular chains inside the sealing material 300 will not have enough time to fully rearrange under the guidance of the pre-tightening force. If the cooling rate is too slow (<0.2℃ / min), the entire encapsulation process cycle will be too long, and it may cause excessive relaxation of the molecular chains inside the sealing material 300, weakening the orientation effect.

[0065] Preferably, the cooling rate is 0.5℃ / min. By precisely controlling the cooling rate, sufficient and suitable kinetic conditions are provided for the sealing material 300 to complete molecular chain rearrangement within the phase change window.

[0066] More specifically, the phase change window is the temperature range in which the energy storage modulus G′ of the sealing material 300 drops below 50% of its initial value during the cooling process, and the loss factor tanδ of the sealing material reaches its peak value. The phase change window is not obtained through real-time online detection during packaging production, but rather through pre-calibration using a dynamic mechanical analyzer (DMA) at the corresponding cooling rate during the process development stage. Therefore, when the sensor and electrical connector 200 are packaged, the cooling program of the programmed temperature cycle is set and controlled according to this pre-calibrated temperature range.

[0067] The phase transition window is a dynamic physical state range; it occurs when the temperature drops to the phase transition temperature T. p When the temperature is near the phase transition point, the phase transition components (such as the microcapsule core material) inside the sealing material 300 melt, causing the overall storage modulus G′ of the sealing material 300 to drop sharply and soften significantly. At the same time, internal friction increases, resulting in a peak in the loss factor tanδ. This region, where the storage modulus trough overlaps with the internal loss peak, represents the optimal kinetic window period in which the sealing material 300 is most sensitive to external mechanical guidance and where molecular chains are most prone to directional rearrangement. Therefore, covering the phase transition window with the cooling process allows the clamping force applied by the clamping tool to exert maximum effectiveness within the phase transition window. The pressure applied by the clamping force can effectively overcome the shrinkage stress of the sealing material 300, driving the formed cross-linked network to undergo directional extension and conformational adjustment in the direction that counteracts future low-temperature shrinkage. As the temperature continues to drop below the phase transition point, the sealing material 300 completely transforms into a solid state and is frozen and fixed, thereby constructing a stable stress-compensating structure inside the sealing material 300.

[0068] Meanwhile, after the sealing material 300 has completely solidified, it needs to be maintained at the second temperature for a preset time, i.e. Figure 4The low-temperature holding stage is used to finalize the stress compensation structure.

[0069] Preferably, when the first temperature is 120°C, the second temperature is -65°C, and the temperature is maintained at -65°C for 60 minutes.

[0070] In some embodiments, the time t during the phase change window period in the cooling process is determined by the phase change temperature T of the sealing material. p Decide, When T p At -60℃, 90min < t < min; When -60℃ ≤T p At ≤ -50℃, 60min < t < 90min; When T p At -50℃, 30min < t ≤ 60min.

[0071] By precisely coordinating programmed temperature cycling, the application of constant preload, and the intrinsic properties of the sealing material 300 (i.e., the phase change window period) in the spatiotemporal dimensions, a fundamental shift in the encapsulation stress control strategy has been achieved, moving from passively resisting thermal stress to actively pre-compensating for stress. Specifically, using the phase change window period as the time reference, constant preload as the spatial constraint, and programmed temperature cycling as the driving force, the external stress field and the internal phase change dynamics of the sealing material are highly coupled during the critical period of molecular chain rearrangement. The resulting stress compensation structure is no longer a residual response after thermal expansion mismatch, but a functional internal stress that is pre-designed, directionally implanted, and permanently frozen during the phase change process. The magnitude and distribution of the internal stress can be precisely preset according to the matching relationship between the phase change temperature, cooling rate, and preload force calibrated by DSC, fundamentally avoiding the risks of interface debonding and encapsulation structure failure caused by stress hysteresis or overshoot in traditional methods.

[0072] In some embodiments, the packaging process for a sensor and electrical connector according to this application further includes: S500 performs electrical continuity and sealing tests on the packaged structure of the sensor and electrical connector, including: S510. Remove clamping parts: After the sealing material temperature of 300°C returns to room temperature, remove the pressing tooling and clamping parts.

[0073] S520, at test temperature T testUnder the condition of ≤-60℃, the packaged structure is subjected to an electrical continuity test with a test duration of ≥100h, which includes: placing the packaged sensor and electrical connector in a high-low temperature test chamber, cooling to -65℃ and stabilizing, then using the four-wire method to monitor the DC resistance R of its critical signal pin circuits for no less than 100 consecutive hours. Taking the initial resistance R0 at room temperature as the reference, the resistance change rate ΔR / R0 is calculated. The test results show that the resistance change rate is stably within ±3%, indicating that the stress compensation structure can effectively stabilize the contact interface between the pin assembly and the sealing material.

[0074] The tightness test includes helium mass spectrometer leak detection and low-temperature vacuum pressure decay test.

[0075] S530. Perform helium mass spectrometer leak detection on the packaged structure at room temperature: use a helium mass spectrometer leak detector to test the packaged structure of the sensor and the electrical connector at room temperature, and the leak rate threshold Q of the packaged structure leak is tested, and the value range of the leak rate threshold must satisfy: Q leak ≤1×10 -9 Pa·m³ / s to be judged as qualified. Helium mass spectrometer leak detection is a direct and high-sensitivity test method for verifying whether there are through leakage defects in the packaged structure at normal temperature.

[0076] After the packaged structure of the present application is tested, the results show that the leak rate threshold Q leak ≤1×10 -9 Pa·m³ / s, all within the normal range, which indicates that the packaged structure has no through leakage defects at normal temperature and has high sensitivity.

[0077] S540. Perform a low-temperature vacuum pressure decay test on the packaged structure in a vacuum chamber: place the packaged structure of the sensor and the electrical connector in a vacuum chamber with programmable temperature control, cool to -60℃ and stabilize, then evacuate until the background pressure is ≤1×10 -3 Pa, hold the pressure for 24 hours, and record the system pressure change rate ΔP / Δt. The value range of the pressure change rate must satisfy: ΔP / Δt ≤5×10 -4 Pa / s to be judged as qualified. The low-temperature vacuum pressure decay test is used to verify whether there is a leakage problem in the package under low-temperature and vacuum environments.

[0078] After the packaged structure of the present application is tested, the results show that the pressure change rate ΔP / Δt ≤5×10 -4 Pa / s, all within the range specified by the qualification judgment standard, which indicates that under the harsh condition of the superposition of extreme low temperature and vacuum environment, the packaged structure will not have the situation of tiny leakage that may be caused by thermal mismatch stress.

[0079] This application physically roughens and chemically activates the sealing groove to prevent debonding failure at the interface between the sealing material and the sealing groove under low-temperature stress. Under constant preload, the sealing material undergoes programmed temperature cycling, and the phase change window is included in the second curing stage. This allows the molecular chains inside the sealing material to complete the orientation rearrangement and network freezing during the modulus softening stage, thereby enhancing the bonding ability and anti-debonding ability of the interface between the sealing material and the sealing groove under thermal stress. This ensures that the packaging structure of the sensor and electrical connector can maintain excellent sealing performance in extreme low-temperature environments and effectively prevent leakage.

[0080] The second curing stage includes a phase change window, allowing the sealing material to be subjected to compressive force during the stage when its modulus changes most sensitively. This guides the polymer molecular chains in the sealing material to undergo rearrangement and cross-linking reactions, thereby transforming macroscopic mechanical constraints into stress compensation structures that are frozen inside the sealing material and can precisely offset the pre-set low-temperature shrinkage direction. This achieves active and directional compensation of internal stress and suppresses fluctuations in pin displacement and contact pressure caused by the cold shrinkage of the sealing material.

[0081] Meanwhile, during programmed temperature cycling, the cooling rate, preload, and phase change rate are coordinated and matched to achieve precise control over different sealing materials. This allows the packaging process of this application to be compatible with a variety of commercial phase change sealing materials without the need to develop special materials, thus reducing the technical threshold and application cost, while ensuring the consistency and repeatability of the packaging process.

[0082] Finally, through electrical continuity and sealing tests on the packaging structure, it was found that the contact resistance change rate of the packaging structure remained at an extremely low level even after long-term testing in extreme low-temperature environments. This ensured the signal transmission stability and environmental isolation of the packaging structure during long-term operation in extreme low-temperature environments.

[0083] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A packaging process for a sensor and an electrical connector, characterized in that, include: A sealing groove is formed on the housing of the sensor, and the sealing groove is pre-treated; The sensor is pre-assembled with the electrical connector, and uncured sealing material is filled into the sealing groove. A clamping element is then installed on the sealing material. A constant preload is applied to the clamping member, which transmits the preload to the sealing material so that the sealing material fits into the sealing groove. The sealing material is heated to enter the first curing stage, which initially forms a cross-linked network inside the sealing material. Then, the sealing material is cooled to enter the second curing stage, where the initially formed cross-linked network is shaped to complete the encapsulation of the sensor and the electrical connector.

2. The packaging process for a sensor and electrical connector according to claim 1, characterized in that, The heating of the sealing material to enter the first curing stage, thereby initially forming a cross-linked network within the sealing material, includes: The sealing material is heated to a first temperature, which is higher than the phase transition temperature of the sealing material, so that the sealing material is in a liquid state; At the same time, the clamping element converts the pre-tightening force into pressure acting on the sealing material, causing the sealing material to initially form a cross-linked network, so that the sealing material has the ability to maintain its shape.

3. The packaging process for a sensor and electrical connector according to claim 2, characterized in that, The subsequent cooling of the sealing material to enter the second curing stage, and the shaping of the initially formed cross-linked network, includes: The sealing material is cooled to a second temperature at a preset cooling rate. The second temperature is lower than the phase transition temperature of the sealing material, causing the sealing material to change from a liquid state to a solid state. During the cooling process, pressure is continuously applied to the sealing material by the clamping component, causing the initially formed cross-linked network to extend in the direction that counteracts the preset low-temperature shrinkage, so as to construct a stress compensation structure in the sealing material; After the sealing material has completely solidified, it is kept at the second temperature for a preset time to shape the stress compensation structure.

4. The packaging process for a sensor and electrical connector according to claim 3, characterized in that, The preload and the cooling rate are related to the phase change temperature T of the sealing material. p Mutual matching includes: When T p When the temperature is below -60℃, the preload force ranges from 5.0MPa to 6.0MPa, and the cooling rate ranges from 0.2℃ / min to 0.5℃ / min. When -60℃≤T p When the temperature is less than -50℃, the preload force ranges from 4.0MPa to 5.0MPa, and the cooling rate ranges from 0.5℃ / min to 0.8℃ / min. When -50℃≤T p When the temperature is below -40℃, the preload force ranges from 3.0MPa to 4.0MPa, and the cooling rate ranges from 0.8℃ / min to 1.2℃ / min. When T p When the temperature is ≥-40℃, the value of the preload is in the range of 1.0MPa~3.0MPa, and the value of the cooling rate is in the range of 1.2℃ / min~1.5℃ / min.

5. The packaging process for a sensor and electrical connector according to claim 3, characterized in that, The temperature change range during the cooling process includes the phase change window period of the sealing material. The phase change window period is the temperature range in which the energy storage modulus of the sealing material decreases to below 50% of its initial value during the cooling process, and the loss factor of the sealing material reaches its peak value.

6. The packaging process for a sensor and electrical connector according to claim 5, characterized in that, The time t during the cooling process through the phase change window period is determined by the phase change temperature T of the sealing material. p Decide, When T p At -60℃, 90min < t < min; When -60℃≤T p At ≤-50℃, 60min<t<90min; When T p At -50℃, 30min < t ≤ 60min.

7. The packaging process for a sensor and electrical connector according to claim 1, characterized in that, A sealing groove is formed on the housing of the sensor, and the sealing groove is pre-treated, including: The sealing groove is physically roughened to reduce its surface roughness R. a The value range is 3.2μm to 12.5μm; The sealing groove is chemically activated to form a chemical transition layer on its surface, the thickness of which ranges from 10. ~50 .

8. The packaging process for a sensor and electrical connector according to claim 1, characterized in that, The electrical connector includes a pin assembly, and the bottom of the sealing groove has a through hole. The process of pre-assembling the sensor with the electrical connector, filling the sealing groove with uncured sealing material, and installing a clamping element on the sealing material includes: One end of the pin assembly passes through the through hole and is connected to the interior of the sensor, while the other end of the pin assembly is connected to the electrical connector; Uncured sealing material is injected into the sealing groove using a precision dispensing device, and the liquid level of the sealing material in the sealing groove is lower than the top of the portion of the pin assembly located in the sealing groove that is not covered by the sealing material, the top being the end face of the pin assembly near the electrical connector. The clamping element is fitted onto the outer periphery of the pin assembly and pressed against the upper surface of the sealing material.

9. The packaging process for a sensor and electrical connector according to claim 1, characterized in that, The packaging process also includes: Remove the clamping element; Electrical continuity and sealing tests were performed on the structure after the sensor and electrical connector were packaged.

10. The packaging process for a sensor and electrical connector according to claim 9, characterized in that, The electrical continuity test and sealing test performed on the packaged structure of the sensor and electrical connector include: At the test temperature T test Under conditions of ≤-60℃, the encapsulated structure is subjected to an electrical continuity test for a test time of ≥100h; The encapsulated structure was subjected to helium mass spectrometry leak detection at room temperature. The encapsulated structure was subjected to a low-temperature vacuum pressure decay test within a vacuum chamber.

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