An integrated temperature sensor and a method of manufacturing the same

Abstract

This invention discloses an integrated temperature sensor and its manufacturing method, comprising a plastic temperature sensing head, a connector, and an NTC thermistor assembly; the terminals and terminal retaining ring are integrally injection molded; the plastic temperature sensing head has a hollow cavity filled with thermally conductive silicone grease; the terminal retaining ring is interference-fitted with the temperature sensing head; the temperature sensing head, retaining ring, and connector are integrally injection molded from the same material. The manufacturing method includes: terminal injection molding, NTC welding, temperature sensing head injection molding, filling with thermally conductive silicone grease, interference fit, and integral injection molding into the finished product. This invention solves the problems of corrosion and detachment of metal temperature sensing heads, slow response, poor insulation, and high cost, improves the response speed by 2-3 seconds, simplifies the process, and has high reliability, making it suitable for automotive ambient temperature detection.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor technology, and more particularly to an integrated temperature sensor for vehicles and its fabrication method. Background Technology

[0002] Currently, automotive temperature sensors generally adopt a split metal temperature sensor structure, with the metal temperature sensor and sensor connector fixed and sealed by adhesive curing. In actual use, the metal temperature sensor is susceptible to corrosion from the external environment of the vehicle; the adhesive layer, under long-term exposure to heat, vibration, and aging, is prone to cracking and peeling, directly leading to sensor temperature failure. At the same time, the adhesive curing process increases production time and manufacturing costs; traditional structures also suffer from slow NTC temperature response time, easy short circuits in the leads, and poor insulation withstand voltage performance, making it difficult to meet the high reliability and long lifespan requirements of automotive applications. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in the prior art and provide an integrated temperature sensor and its manufacturing method. This invention uses a plastic temperature sensing head and a sensor connector to be integrally injection molded, which can avoid the risk of temperature sensing failure caused by corrosion or detachment of the temperature sensing head. In addition, the manufacturing process reduces the process of applying glue to fix the temperature sensing head and the connector, thereby reducing the manufacturing cost to a certain extent.

[0004] The technical solution of this invention is: an integrated temperature sensor, including a temperature sensing head, a connector, and an NTC thermistor assembly; characterized in that: the temperature sensing head is a plastic temperature sensing head; the interior of the plastic temperature sensing head is a hollow cavity, and the bottom of the hollow cavity is filled with thermally conductive silicone grease; the NTC thermistor assembly includes terminals, a terminal retaining ring, and an NTC thermistor, the terminals and the terminal retaining ring are integrally injection molded, and the terminal retaining ring is interference-fitted with the plastic temperature sensing head; the plastic temperature sensing head, the terminal retaining ring, and the connector are made of the same material and are integrally injection molded.

[0005] Preferably, the NTC thermistor includes an NTC thermistor chip and an NTC lead. One end of the NTC lead is connected to the NTC thermistor chip by soldering, and the other end is connected to a terminal by either soldering or resistance soldering, wherein the soldering temperature is 250°C to 300°C.

[0006] Preferably, the terminal retaining ring has ribs to isolate the NTC leads and prevent short circuits.

[0007] Furthermore, the terminal is made of phosphor bronze with a tin plating of 0.05~5μm on the surface; the interference fit between the terminal fixing ring and the plastic temperature sensor head on one side is 0.05~0.25mm.

[0008] Preferably, the plastic temperature sensor, terminal retaining ring, and connector are made of either PBT or PA material.

[0009] Preferably, the NTC thermistor is externally covered with an epoxy resin insulating layer with a thickness of 0.1~2mm.

[0010] Preferably, the thermal grease has a thermal conductivity ≥1.4W / (m・K) and a filling height of 1~6mm.

[0011] This invention provides a method for fabricating an integrated temperature sensor, which mainly includes the following steps: S1: First, the terminal and the terminal retaining ring are integrally injection molded; In this step, the terminals are made of phosphor bronze and formed by stamping. The plastic material is either PBT or PA. During injection molding, the drying temperature of the plastic particles is 120℃~140℃, the drying time is 4~6h, and the mold temperature is set at 80℃~100℃ to improve the dimensional stability after molding.

[0012] S2: Solder the NTC thermistor to the terminal to make it conductive; In this step, the NTC thermistor chip and NTC leads of the NTC thermistor are wrapped with a layer of epoxy resin. The epoxy resin coating thickness is 0.1~2mm to meet the requirements of insulation resistance DC500V for 60s, insulation resistance ≥10MΩ, withstand voltage AC1800V for 5s, and leakage current ≤1mA. The temperature sensor NTC chip is sintered at high temperature with one of the following raw material formulas: Mo / Co, Mo / Ni, Mo / Co / Ni, Mo / Co / Fe, or Mo / Co / Ni / Fe. Then, the electrode is deposited with Au or Ag or one of these. The NTC lead material is Cu-Ni alloy wire.

[0013] S3: Injection-molded plastic temperature sensor with a hollow cavity; In this step, the plastic material of the plastic temperature sensor is either PBT or PA, which is the same material as the terminal retaining ring in S1, and the molding conditions are also the same. S4: Fill the bottom of the hollow cavity with thermal grease; The thermal grease used in this step has a thermal conductivity ≥1.4W / (m·K) and an operating temperature range of -30℃ to 230℃. It is filled to the bottom of the hollow cavity of the plastic temperature sensor by 1~6mm to ensure that the thermal grease completely covers the epoxy resin insulating layer of the NTC thermistor.

[0014] S5: The terminal retaining ring and the plastic temperature sensing head are interference-fitted to form a semi-finished product; In this step, the plastic temperature sensor and the terminal retaining ring are designed with an interference fit to form a combined semi-finished product. The interference fit on one side is designed to be 0.05~0.25mm. A small boss is designed at the bottom of the terminal retaining ring in the NTC welding direction. In the example, the outer diameter of the boss is φ5mm and the inner diameter of the temperature sensor is φ4.9mm. This ensures that the plastic temperature sensor is easy to assemble and will not fall off after assembly. The NTC chip of this combined semi-finished product is wrapped with thermal grease at the bottom of the hollow cavity of the plastic temperature sensor, which can improve the NTC response time by 2~3s and improve the detection speed of the temperature sensor. In addition, the NTC lead wire diameter is designed to be φ0.3~φ0.5mm to prevent vibration deformation. The spacing between the NTC soldering positions corresponding to the terminals is designed to be 2~2.5mm. The maximum outer diameter of the NTC temperature sensor is ≤2.2mm. The inner diameter of the hollow cavity inside the plastic temperature sensor is ≥φ3mm. The gap between the NTC lead wire and the hollow cavity inside the plastic temperature sensor is controlled to be ≥0.2mm to prevent the NTC and NTC lead wire from deforming and breaking when they hit the inner wall of the hollow cavity inside the plastic temperature sensor during vibration, thereby improving the reliability of the NTC. S6: Inject the semi-finished product and the connector together to obtain the finished product; This step involves injection molding the NTC assembly semi-finished product and the connector into a single integrated temperature sensor. The terminal retaining ring, plastic temperature sensor, and connector are made of either PBT or PA material, or other suitable materials. The distance between the bottom of the connector and the bottom of the terminal retaining ring is ≥0.5mm, meaning the molten plastic thickness of the connector and the plastic temperature sensor is ≥0.5mm. In this example, the molten plastic thickness is 0.8~1.2mm, which facilitates better melting and fusion of the same material during injection molding, increasing the sensor's bonding strength and preventing the plastic temperature sensor from detaching.

[0015] Preferably, in step S1, ribs are provided on the terminal fixing ring, the metal terminal is made of phosphor bronze with good weldability and conductivity, is formed by stamping, and is tin-plated on the surface with a thickness of 0.05~5μm to improve the insertion and extraction life of the connector terminal.

[0016] Preferably, S2 is manufactured using the following process: (1) Raw material metering and mixing → granulation → body pressing and molding → ceramic firing → body slicing → electrode plating → element cutting → impedance selection; wherein the body is pressed and molded by a press with a pressing force of 1400KN~1600KN, the ceramic high-temperature firing temperature is controlled between 700℃~900℃, the electrode plating temperature is controlled between 100℃~300℃, and the NTC thermistor chip is produced after impedance selection. (2) The NTC leads are connected to the NTC thermistor chip by soldering. The soldering temperature is 250℃~300℃, which can effectively improve the soldering strength. (3) The NTC thermistor chip and NTC leads soldered in (2) are coated with epoxy resin twice to form an insulating layer with a thickness of 0.1~2mm. The epoxy resin mixing ratio and curing temperature / time are as follows: First coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥1h; Second coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥2h.

[0017] The present invention has the following beneficial effects: (1) This integrated temperature sensor provides a novel temperature sensor design and manufacturing method. By designing a plastic temperature sensing head and integrally injection molding it with the sensor connector, the risk of temperature sensing failure caused by corrosion and detachment of the temperature sensing head can be avoided. In terms of manufacturing process, the process of applying glue and curing the temperature sensing head and connector is reduced, which reduces the manufacturing cost to a certain extent. (2) The integrated ambient temperature sensor uses the same plastic material for the plastic temperature sensor head and connector. When it is injection molded, it can be better integrated into one, which improves the bonding strength between the two and avoids the risk of the temperature sensor head falling off. (3) In this invention, the plastic temperature sensor is designed as a hollow cavity, and the terminals and terminal fixing rings in the NTC component are designed as an integral injection molding. Thermal grease is applied to the bottom of the hollow cavity and then injection molded in an integral manner with the terminal fixing rings in the NTC component. This improves the temperature response time of the NTC. The NTC component is formed by designing the terminals and terminal fixing rings as an integral injection molding and then connecting the NTC leads to the terminals by resistance welding or soldering. (4) The ribs of the terminal fixing ring can effectively separate the NTC leads and avoid the risk of NTC short circuit. The metal temperature sensor is designed as a plastic temperature sensor, which can minimize the NTC insulation withstand voltage failure. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention. Figure 2 Top view of the present invention Figure 3 for Figure 2 AA section view Figure 4 This is a schematic diagram of the NTC thermistor assembly in this invention. Figure 5This is a schematic diagram of the NTC thermistor assembly with the thermistor mounted in this invention. Figure 6 The flowchart is of the manufacturing method of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. “Multiple” generally includes at least two, but does not exclude the inclusion of at least one.

[0021] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0022] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0023] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0024] like Figures 1 to 5As shown, an integrated temperature sensor of the present invention includes an NTC thermistor assembly 100, a plastic temperature sensing head 200, and a connector 300.

[0025] The NTC thermistor assembly 100 in this embodiment includes a terminal 101, a terminal retaining ring 102, and an NTC thermistor 103. The terminal 101 and the terminal retaining ring 102 are integrally injection molded, and the terminal retaining ring 102 is interference-fitted with the plastic temperature sensor 200. The plastic temperature sensor 200, the terminal retaining ring 102, and the connector 300 are made of the same material and are integrally injection molded.

[0026] In this embodiment, the interior of the plastic temperature sensor 200 is a hollow cavity 201, and the bottom of the hollow cavity 201 is filled with thermally conductive silicone grease; the thermal conductivity of the thermally conductive silicone grease is ≥1.4W / (m・K), and the filling height is 1~6mm.

[0027] The NTC thermistor 103 in this embodiment includes an NTC thermistor chip 131 and an NTC lead 132. One end of the NTC lead 132 is connected to the NTC thermistor chip 131 by soldering, and the other end is connected to a terminal by either soldering or resistance soldering, wherein the soldering temperature is 250℃~300℃.

[0028] Preferably, the terminal retaining ring 102 is provided with a rib 121 to isolate the NTC lead 132 to prevent short circuit. In this embodiment, the terminal 101 is made of phosphor bronze with a tin plating of 0.05~5μm; the interference fit between the terminal retaining ring 102 and the plastic temperature sensor 200 on one side is 0.05~0.25mm.

[0029] The plastic temperature sensor 200, terminal retaining ring 102, and connector 300 are made of PBT or PA. In this embodiment, the NTC thermistor 103 is externally covered with an epoxy resin insulating layer with a thickness of 0.1~2mm.

[0030] Reference process Figure 6 As shown, this invention provides a method for fabricating an integrated temperature sensor, which mainly includes the following steps: S1: First, the terminal and the terminal retaining ring are integrally injection molded; In this step, the terminals are made of phosphor bronze and formed by stamping. The plastic material is either PBT or PA. During injection molding, the drying temperature of the plastic particles is 120℃~140℃, the drying time is 4~6h, and the mold temperature is set at 80℃~100℃ to improve the dimensional stability after molding.

[0031] S2: Solder the NTC thermistor to the terminal to make it conductive; In this step, the NTC thermistor chip and NTC leads of the NTC thermistor are wrapped with a layer of epoxy resin. The epoxy resin coating thickness is 0.1~2mm to meet the requirements of insulation resistance DC500V for 60s, insulation resistance ≥10MΩ, withstand voltage AC1800V for 5s, and leakage current ≤1mA. The temperature sensor NTC chip is sintered at high temperature with one of the following raw material formulas: Mo / Co, Mo / Ni, Mo / Co / Ni, Mo / Co / Fe, or Mo / Co / Ni / Fe. Then, the electrode is deposited with Au or Ag or one of these. The NTC lead material is Cu-Ni alloy wire.

[0032] S3: Injection-molded plastic temperature sensor with a hollow cavity; In this step, the plastic material of the plastic temperature sensor is either PBT or PA, which is the same material as the terminal retaining ring in S1, and the molding conditions are also the same. S4: Fill the bottom of the hollow cavity with thermal grease; The thermal grease used in this step has a thermal conductivity ≥1.4W / (m·K) and an operating temperature range of -30℃ to 230℃. It is filled to the bottom of the hollow cavity of the plastic temperature sensor by 1~6mm to ensure that the thermal grease completely covers the epoxy resin insulating layer of the NTC thermistor.

[0033] S5: The terminal retaining ring and the plastic temperature sensing head are interference-fitted to form a semi-finished product; In this step, the plastic temperature sensor and the terminal retaining ring are designed with an interference fit to form a combined semi-finished product. The interference fit on one side is designed to be 0.05~0.25mm. A small boss is designed at the bottom of the terminal retaining ring in the NTC welding direction. In the example, the outer diameter of the boss is φ5mm and the inner diameter of the temperature sensor is φ4.9mm. This ensures that the plastic temperature sensor is easy to assemble and will not fall off after assembly. The NTC chip of this combined semi-finished product is wrapped with thermal grease at the bottom of the hollow cavity of the plastic temperature sensor, which can improve the NTC response time by 2~3s and improve the detection speed of the temperature sensor. In addition, the NTC lead wire diameter is designed to be φ0.3~φ0.5mm to prevent vibration deformation. The spacing between the NTC soldering positions corresponding to the terminals is designed to be 2~2.5mm. The maximum outer diameter of the NTC temperature sensor is ≤2.2mm. The inner diameter of the hollow cavity inside the plastic temperature sensor is ≥φ3mm. The gap between the NTC lead wire and the hollow cavity inside the plastic temperature sensor is controlled to be ≥0.2mm to prevent the NTC and NTC lead wire from deforming and breaking when they hit the inner wall of the hollow cavity inside the plastic temperature sensor during vibration, thereby improving the reliability of the NTC. S6: Inject the semi-finished product and the connector together to obtain the finished product; This step involves injection molding the NTC assembly semi-finished product and the connector into a single integrated temperature sensor. The terminal retaining ring, plastic temperature sensor, and connector are made of either PBT or PA material, or other suitable materials. The distance between the bottom of the connector and the bottom of the terminal retaining ring is ≥0.5mm, meaning the molten plastic thickness of the connector and the plastic temperature sensor is ≥0.5mm. In this example, the molten plastic thickness is 0.8~1.2mm, which facilitates better melting and fusion of the same material during injection molding, increasing the sensor's bonding strength and preventing the plastic temperature sensor from detaching.

[0034] Preferably, in step S1, ribs are provided on the terminal fixing ring, the metal terminal is made of phosphor bronze with good weldability and conductivity, is formed by stamping, and is tin-plated on the surface with a thickness of 0.05~5μm to improve the insertion and extraction life of the connector terminal.

[0035] Preferably, S2 is manufactured using the following process: (1) Raw material metering and mixing → granulation → body pressing and molding → ceramic firing → body slicing → electrode plating → element cutting → impedance selection; wherein the body is pressed and molded by a press with a pressing force of 1400KN~1600KN, the ceramic high-temperature firing temperature is controlled between 700℃~900℃, the electrode evaporation temperature is controlled between 100℃~300℃, and the NTC thermistor chip is produced after impedance selection. (2) The NTC leads are connected to the NTC thermistor chip by soldering. The soldering temperature is 250℃~300℃, which can effectively improve the soldering strength. (3) The NTC thermistor chip and NTC leads soldered in (2) are coated with epoxy resin twice to form an insulating layer with a thickness of 0.1~2mm. The epoxy resin mixing ratio and curing temperature / time are as follows: First coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥1h; Second coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥2h.

[0036] This invention uses a plastic temperature sensor instead of a metal one, eliminating the risk of corrosion; it is integrally injection molded from the same material, eliminating the risk of adhesive layer peeling off and significantly improving reliability; it eliminates the adhesive application and curing processes, simplifying the process and reducing manufacturing costs; the temperature response time of this invention is faster, using a hollow cavity + thermal grease + interference fit, which improves the NTC temperature response speed by 2-3 seconds; the terminal fixing ring rib of this invention isolates the lead wire, and the thick layer of epoxy resin provides excellent insulation and withstand voltage, reducing the defect rate; in addition, the reasonable design of the size gap and interference fit avoids vibration damage and meets the harsh automotive environment.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the claims of this invention should fall within the technical scope of this invention.

Claims

1. An integrated temperature sensor, comprising a temperature sensing head, a connector, and an NTC thermistor assembly; characterized in that: The temperature sensor is a plastic temperature sensor; the inside of the plastic temperature sensor is a hollow cavity, and the bottom of the hollow cavity is filled with thermally conductive silicone grease; the NTC thermistor assembly includes terminals, terminal retaining rings, and an NTC thermistor, the terminals and terminal retaining rings are integrally injection molded, and the terminal retaining rings are interference-fitted with the plastic temperature sensor; the plastic temperature sensor, terminal retaining rings, and connectors are made of the same material and are integrally injection molded.

2. The integrated temperature sensor according to claim 1, characterized in that: The NTC thermistor includes an NTC thermistor chip and an NTC lead. One end of the NTC lead is connected to the NTC thermistor chip by soldering, and the other end is connected to a terminal by either soldering or resistance soldering, wherein the soldering temperature is 250℃~300℃.

3. The integrated temperature sensor according to claim 2, characterized in that: The terminal retaining ring has ribs to isolate the NTC leads and prevent short circuits.

4. The integrated temperature sensor according to claim 3, characterized in that: The terminal is made of phosphor bronze with a tin plating of 0.05~5μm on the surface; the interference fit between the terminal fixing ring and the plastic temperature sensor head on one side is 0.05~0.25mm.

5. The integrated temperature sensor according to claim 1, characterized in that: The plastic temperature sensor, terminal retaining ring, and connector are made of either PBT or PA.

6. The integrated temperature sensor according to claim 2, characterized in that: The NTC thermistor is externally covered with an epoxy resin insulating layer with a thickness of 0.1~2mm.

7. The integrated temperature sensor according to claim 1, characterized in that: The thermal grease has a thermal conductivity ≥1.4W / (m・K) and a filling height of 1~6mm.

8. A method for fabricating an integrated temperature sensor, characterized in that, Includes the following steps: S1: First, the terminal and the terminal retaining ring are integrally injection molded; In step S1, the terminal is made of phosphor bronze and is formed by stamping. The plastic material is either PBT or PA. S2: Solder the NTC thermistor to the terminal to make it conductive; In step S2, the NTC thermistor chip and NTC leads of the NTC thermistor are wrapped with a layer of epoxy resin. S3: Injection-molded plastic temperature sensor with a hollow cavity; In step S3, the plastic material of the plastic temperature sensor is either PBT or PA. S4: Fill the bottom of the hollow cavity with thermal grease; The thermal grease used in step S4 has a thermal conductivity ≥1.4W / (m·K) and an operating temperature range of -30℃ to 230℃. It is filled to the bottom of the hollow cavity of the plastic temperature sensor by 1~6mm. S5: The terminal retaining ring and the plastic temperature sensing head are interference-fitted to form a semi-finished product; In step S5, the plastic temperature sensor and the terminal retaining ring are designed to be interference-fitted to form a combined semi-finished product. S6: Inject the semi-finished product and the connector together to obtain the finished product; In step S6, the NTC assembly semi-finished product and the connector are injection molded together to form an integrated temperature sensor.

9. The method according to claim 8, characterized in that: In step S1, during injection molding, the drying temperature of the plastic particles is 120℃~140℃, the drying time is 4~6h, and the mold temperature is set at 80℃~100℃ to improve the dimensional stability after molding. In step S1, ribs are provided on the terminal fixing ring, and the metal terminal is made of phosphor bronze material with good weldability and conductivity. It is formed by stamping and tin-plated on the surface with a thickness of 0.05~5μm to improve the insertion and extraction life of the connector terminal. In step S2, the epoxy resin coating thickness is 0.1~2mm to meet the requirements of insulation resistance DC500V for 60s, insulation resistance ≥10MΩ, withstand voltage AC1800V for 5s, and leakage current ≤1mA. The temperature sensor NTC chip is sintered at high temperature using one of the following raw material formulations: Mo / Co, Mo / Ni, Mo / Co / Ni, Mo / Co / Fe, or Mo / Co / Ni / Fe. Then, the electrode is plated with one of Au or Ag. The NTC lead material is Cu-Ni alloy wire. In step S2, it is manufactured through the following process: (1) Raw material metering and mixing → granulation → body pressing and molding → ceramic firing → body slicing → electrode plating → element cutting → impedance selection; wherein the body is pressed and molded by a press with a pressing force of 1400KN~1600KN, the ceramic high-temperature firing temperature is controlled between 700℃~900℃, the electrode plating temperature is controlled between 100℃~300℃, and the NTC thermistor chip is produced after impedance selection. (2) The NTC leads are connected to the NTC thermistor chip by soldering. The soldering temperature is 250℃~300℃, which can effectively improve the soldering strength. (3) The NTC thermistor chip and NTC leads soldered in (2) are coated with epoxy resin twice to form an insulating layer with a thickness of 0.1~2mm. The epoxy resin mixing ratio and curing temperature / time are as follows: First coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥1h; Second coating: Main agent: Hardener: Thinner = 7:2:3 Curing temperature / time: 105℃±5℃, ≥2h.

10. The method according to claim 8, characterized in that: In step S5, the single-sided interference is designed to be 0.05~0.25mm, and a small boss is designed at the bottom of the terminal fixing ring in the NTC welding direction. In one embodiment, the outer diameter of the boss is φ5mm and the inner diameter of the temperature sensor is φ4.9mm. This ensures that the plastic temperature sensor is easy to assemble and will not fall off after assembly. The NTC chip of this assembled semi-finished product is wrapped with thermal grease at the bottom of the hollow cavity of the plastic temperature sensor, which can improve the NTC response time by 2~3s and improve the detection speed of the temperature sensor. In step S5, the NTC lead wire diameter is designed to be φ0.3~φ0.5mm to prevent vibration deformation. The spacing between the NTC soldering positions corresponding to the terminals is designed to be 2~2.5mm. The maximum outer diameter of the NTC temperature sensor is ≤2.2mm. The inner diameter of the hollow cavity inside the plastic temperature sensor is ≥φ3mm. The gap between the NTC lead wire and the hollow cavity inside the plastic temperature sensor is controlled to be ≥0.2mm to prevent the NTC and NTC lead wire from deforming and breaking when they hit the inner wall of the hollow cavity inside the plastic temperature sensor during vibration, thereby improving the reliability of the NTC. In step S6, the terminal retaining ring, the plastic temperature sensor, and the connector are made of either PBT or PA material. Alternatively, other materials that meet the requirements can be selected. The distance between the bottom of the connector and the bottom of the terminal retaining ring is ≥0.5mm, meaning the plastic melting thickness of the connector and the plastic temperature sensor is ≥0.5mm. This facilitates better melting and fusion of the same material during integral injection molding, increases the bonding strength of the sensor, and avoids the risk of the plastic temperature sensor falling off.

Images