A pressure-temperature combination sensor and a manufacturing method thereof

Abstract

The application discloses a pressure and temperature combined sensor and a manufacturing method thereof, and relates to the technical field of pressure sensors.The sensor comprises a pressure sensor chip, an inner sealing ring, a shell, a temperature sensor assembly, an FPCA circuit board, a connector and an outer sealing ring; the pressure sensing part adopts a single sealing structure, which simplifies assembly, improves sealing effect and reduces cost; the temperature sensor assembly adopts lead welding and then integral injection molding and an open type liquid-tight channel, which accelerates temperature response, avoids lead vibration fracture and short circuit and open circuit; the shell is provided with multi-stage limiting steps and an integrally formed NTC protection ring, which reduces the risk of chip stress cracking and protection ring falling off.The manufacturing method comprises the steps of temperature assembly injection molding and welding, chip assembly, riveting and fixing, high-temperature aging and solidification sealing and the like.The application realizes reliable sealing, rapid temperature measurement, anti-vibration durability, lower cost and stable process, and can meet the use of high-pressure, strong vibration and high-precision detection scenes.

Description

Technical Field

[0001] This invention relates to a sensor, and more particularly to a pressure-temperature combined sensor and its manufacturing method. Background Technology

[0002] Currently, pressure-temperature combination sensors are widely used in automotive, HVAC, refrigeration, and industrial control fields to simultaneously detect the pressure and temperature signals of fluid media. Existing mainstream pressure-temperature combination sensors generally employ a secondary sealing structure for the pressure sensor and a closed temperature sensing structure, which has several shortcomings in practical assembly, use, and long-term reliability, as detailed below: 1) Pressure sensors have complex sealing structures, poor sealing reliability, and high costs; The pressure sensing component of existing pressure-temperature combined sensors generally employs a structure design with two sealing rings for secondary sealing. This approach requires multiple layers of sealing grooves and assembly positioning structures within the sensor housing, resulting in a large number of components, cumbersome assembly processes, and a significant increase in labor and equipment costs.

[0003] Meanwhile, secondary sealing relies on the coordinated deformation of two sealing rings, which can easily lead to problems such as sealing ring misalignment, uneven compression, and extrusion failure during assembly. Long-term use can result in media leakage and poor pressure seal stability. Furthermore, the multi-seal structure places extremely high demands on the machining precision of the outer shell and the dimensional accuracy of the sealing rings, further increasing material and manufacturing costs.

[0004] 2) The temperature sensor has a slow response speed and significant temperature measurement lag; The temperature sensing units of existing products are mostly enclosed in a closed liquid-tight channel. The fluid medium needs to pass through multiple shells, sealing structures or partitions to contact the temperature sensing chip. The heat conduction path is long and the thermal resistance is high, which significantly prolongs the response time of the temperature sensor. It cannot quickly and accurately reflect the real-time temperature of the medium and cannot meet the requirements of high-precision and fast-response measurement and control.

[0005] 3) Temperature sensor leads are prone to vibration breakage and have a high risk of short circuit / open circuit; Existing temperature sensor leads typically employ simple soldering followed by adhesive bonding or a semi-enclosed structure, without overall reinforcement and protection. Under conditions such as vehicle operation, equipment vibration, and fluid impact, the lead root and solder joint are subjected to alternating stress over a long period, making them highly susceptible to fatigue deformation, bending, or even breakage. This directly leads to open circuits, short circuits, or signal drift in the temperature signal, causing sensor failure and compromising reliability and lifespan. Summary of the Invention

[0006] The purpose of this invention is to solve the problems in the prior art and provide a pressure-temperature combined sensor and its manufacturing method.

[0007] The technical solution of this invention is: a pressure-temperature combined sensor, comprising a pressure sensor chip, a housing, a temperature sensor assembly, an FPCA circuit board, an inner sealing ring, a connector, and an outer sealing ring; characterized in that: the pressure sensor chip and the housing are sealed once by the inner sealing ring; the outer sealing ring is located outside the housing; the terminals of the temperature sensor assembly are connected to the NTC pin at the bottom of the pressure sensor chip by resistance welding; the temperature sensor assembly, after being connected by resistance welding of the terminals and the NTC lead, is an integral injection-molded structure and has an open liquid-tight temperature channel.

[0008] Preferably, the pressure sensor chip has a ceramic substrate on its upper surface and a ceramic diaphragm on its lower surface; the ceramic diaphragm and the ceramic substrate are sintered at a high temperature of 600℃~800℃ through a sealing glass; the ceramic substrate on the upper surface has multiple signal output pins; the ceramic diaphragm on the lower surface has multiple NTC pins; and an electrode cavity is located in the upper middle of the ceramic diaphragm.

[0009] Furthermore, the NTC PIN is made of stainless steel, passes through the ceramic base and the ceramic diaphragm, and protrudes from both sides; there are three signal output PINs, namely the power PIN, the signal PIN, and the ground PIN.

[0010] Preferably, the temperature sensor assembly includes an NTC thermistor, metal terminals, and an injection-molded plastic body; the NTC thermistor includes an NTC thermistor chip and NTC leads, and is externally wrapped with epoxy resin with a thickness of 0.1mm to 1mm; the NTC leads are Cu-Ni alloy wires, which are integrally injection molded and wrapped after being resistively welded to the metal terminals.

[0011] Preferably, the metal terminal is made of phosphor bronze with a tin plating thickness of 0.5μm to 6μm; the injection-molded plastic body is made of PPE+PA or PEI material; and the NTC lead is coated with epoxy resin with a thickness of 0.05mm to 0.5mm at the demolding gap.

[0012] Furthermore, the injection-molded plastic body is provided with a glue storage tank and a plastic boss; the glue storage tank is filled with epoxy resin to cover the welding parts of the temperature sensor assembly and the pressure sensor chip, as well as the exposed metal parts.

[0013] Preferably, the outer shell is provided with a groove, a first stepped surface, a second stepped surface, a third stepped surface, and a through-hole inner ring; the inner sealing ring is installed in the groove, and the groove height is 0.5mm~1.5mm.

[0014] Furthermore, the housing and connector are fixed by riveting, and the end face of the connector is supported and limited by the first step surface of the housing, with a gap a=0mm; the gap b between the second step surface of the housing and the bottom of the pressure sensor chip is 0.2mm~0.5mm; the gap c between the third step surface of the housing and the plastic boss of the temperature sensor assembly is 0.1mm~0.3mm; the gaps satisfy b>c>a=0; or a buffer pad is simultaneously set at the gap b.

[0015] Furthermore, the NTC protection ring is integrally formed with the outer shell, and a notch is formed on the side; the top of the notch shields the NTC thermistor.

[0016] Preferably, the open-type liquid-tight temperature channel is type I, which is formed by the temperature sensor assembly, the inner ring of the outer shell through hole, the inner sealing ring and the bottom of the pressure sensor chip; the open-type liquid-tight pressure channel is formed by the combination of the internal fluid pressure channel and the external fluid pressure channel, and its shape is L-shaped; the pressure channel and the temperature channel are not parallel to each other.

[0017] The present invention also provides a method for manufacturing a pressure-temperature combined sensor, characterized by comprising the following steps: S1: First, the NTC lead of the temperature sensor assembly is resistively soldered to the metal terminal, and then it is integrally injection molded. Epoxy resin is applied to the demolding gap for curing and insulation. S2: The metal terminals of the temperature sensor assembly are resistively soldered to the NTC pins of the pressure sensor chip, and epoxy resin is applied to the soldered area and the exposed metal for curing and insulation. S3: Further, prepare the FPCA circuit board by SMT assembly and install the pressure signal conditioning chip and passive components. S4: Solder the PIN pins and connector terminals of the pressure sensor chip to the FPCA circuit board to form a semi-finished product; S5: Prepare the outer shell and inner sealing ring, install the inner sealing ring into the groove of the outer shell, install the semi-finished product from step S4 into the inner cavity of the outer shell, and rivet the outer shell and connector to fix them. S6: The finished product in S5 above is subjected to high-temperature aging to relieve stress. The temperature is controlled at 100℃~150℃ and the action time is 1~5h. After the high-temperature aging is completed, the riveted parts of the finished product are coated with glue for curing and sealing. S7: Finally, install the cured finished product with the outer sealing ring to complete the entire manufacturing process.

[0018] Preferably, in step S1, the metal terminals of the temperature sensor assembly are made of phosphor bronze, formed by stamping, and tin-plated with 0.5~6μm on the surface. They are then resistively soldered to the NTC leads. The plastic material is either PPE+PA or PEI. During injection molding, the plastic particles are dried at a temperature of 95℃~105℃ for 3~4 hours, and the mold temperature is set at 80℃~120℃. Alternatively, the plastic particles are dried at a temperature of 150℃ for 4~6 hours, and the mold temperature is set at 140℃~180℃.

[0019] Furthermore, when the NTC lead and the terminal resistance-welded semi-finished product are integrally injection molded, a gap of 0.2~1.5mm is left at the end of the NTC lead. The mold insert clamps the NTC lead through this gap, which facilitates demolding. The other parts of the NTC lead, the resistance-welded area, and the terminal 4-2 are integrally molded to prevent the NTC lead from deforming or breaking due to vibration or drops. The demolding gap of the temperature sensor assembly lead after integral injection molding is treated with epoxy resin insulation. The epoxy resin thickness is controlled at 0.05~0.5mm to avoid the risk of short circuit or open circuit of the temperature sensor and to meet the insulation withstand voltage requirements of the temperature sensor.

[0020] Furthermore, the NTC thermistor of the temperature sensor assembly in step S1 includes an NTC thermistor chip and NTC leads, and is coated with an epoxy resin layer with a coating thickness of 0.1~1mm; the NTC chip of the temperature sensor 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, and then plated with one of the following electrodes: Au or Ag; the NTC lead material is Cu-Ni alloy wire.

[0021] Preferably, the pressure sensor chip in step S2 mainly has two working principles: piezoresistive and piezoresistive. The piezoresistive type is a variable-gap parallel capacitor, which is composed of a thick ceramic substrate, a signal output PIN, a parallel gold electrode cavity, a thin ceramic diaphragm, a sealing glass, and an NTC PIN.

[0022] Furthermore, the ceramic diaphragm senses pressure and undergoes corresponding displacement (pressure → displacement). Gold electrodes are silkscreened on the ceramic diaphragm and ceramic base, forming a parallel plate capacitor in pairs, converting pressure into a capacitance signal (displacement → capacitance). The capacitance value is calculated using the formula: C = εS / 4πkd, where: C: capacitance value, ε: dielectric constant of the medium between the plates, S: area of ​​the upper and lower plates facing each other, k: electrostatic constant, d: distance between the upper and lower plates. The signal output PIN outputs the capacitance signal to the FPCA circuit board.

[0023] Furthermore, there are three signal output pins: a power pin, a signal pin, and a ground pin. These pins pass through three holes in the ceramic substrate. The ceramic diaphragm and the ceramic substrate are sintered at high temperature using sealed glass, with the sintering temperature controlled between 600°C and 800°C. The NTC pins are made of stainless steel, with two pins passing through holes in the ceramic substrate and the ceramic diaphragm. The NTC pins are also through holes on both sides. The ceramic diaphragm side connects to the NTC, and the ceramic substrate side connects to the FPCA. Preferably, the manufacturing method of the pressure sensor chip is as follows: First, the ceramic substrate and ceramic film are formed and drilled → gold electrode printing → sealing glass glue is applied → sintering → glue dispensing → PIN insertion → high temperature curing → capacitance testing, and the sintering temperature is controlled at 600℃~800℃. Preferably, the adhesive reservoir of the temperature sensor assembly is coated with epoxy resin adhesive, and the adhesive covers the resistance solder joint of the temperature sensor assembly and the pressure sensor chip, as well as the exposed metal parts. After the epoxy resin adhesive is cured at high temperature, it plays an insulating role.

[0024] Preferably, the FPC material of the FPCA circuit board in step S3 is PI, with a thickness of 0.1~0.15mm. The signal conditioning chip is calibrated through a combination of multiple pressure points and multiple temperature points, converting the received capacitance or resistance value of the pressure sensor chip into a voltage signal, a Sent signal, or a LIN protocol signal, which can reduce temperature drift and improve pressure output accuracy.

[0025] Preferably, in step S4, the connector 6 and the metal terminal are made of phosphor bronze material, formed by stamping, and tin-plated on the surface with a thickness of 0.5~6μm. The plastic material is either PPE+PA or PEI material, formed by injection molding.

[0026] Preferably, the inner sealing ring in step S5 is made of HNBR with a hardness of Shore A 70~90, is resistant to cold media, and has a temperature resistance of -40℃~150℃. The inner sealing ring wire diameter is set to φ1.5~φ2mm. The outer shell material is one of aluminum alloy, copper, or stainless steel. The outer shell is provided with grooves, the height of which is set to 0.5~1.5mm. The outer shell is provided with a riveting support limiting step surface. After riveting, the inner sealing ring is compressed and deformed to achieve the sealing function.

[0027] Preferably, the inner sealing ring in step S5 is made of HNBR with a hardness of Shore A 70~90, is resistant to cold media, and has a temperature resistance of -40℃~150℃. The inner sealing ring wire diameter is set to φ1.5~φ2mm. The outer shell material is one of aluminum alloy, copper, or stainless steel. The outer shell is provided with grooves, the height of which is set to 0.5~1.5mm. The outer shell is provided with a riveting support limiting step surface. After riveting, the inner sealing ring is compressed and deformed to achieve the sealing function.

[0028] Furthermore, the adhesive in step S6 is silicone or another type of adhesive, which cures at room temperature and can be used for turnover and testing after 10 minutes to 1 hour of surface drying. This can shorten the curing and placement time of the product and meet IP67 and IP69K requirements.

[0029] Compared with the prior art, the present invention has the following significant advantages: 1) This invention adopts a single-seal structure for pressure sensors to replace the traditional secondary seal, which effectively simplifies the assembly process, reduces the number of parts, significantly reduces material and manufacturing costs, and at the same time significantly improves the pressure sealing effect and sealing reliability, thus preventing media leakage.

[0030] 2) The temperature sensor is set as an open liquid-tight channel structure, which greatly shortens the heat conduction path, reduces thermal resistance, and effectively improves the response speed of the temperature sensor. It can quickly and accurately reflect the real-time temperature of the measured medium and eliminate temperature measurement lag. The flow channel layout of L-shaped pressure open liquid-tight channel and I-shaped temperature open liquid-tight channel is not parallel to each other, which optimizes the fluid flow field, avoids the interference of pressure fluctuations on temperature detection, reduces medium retention and bubble adhesion, and improves the stability and consistency of pressure and temperature detection.

[0031] 3) The temperature sensor leads are welded and then integrally injection molded. Epoxy resin is cured and insulated during the demolding gap, so that the leads and the welded parts are completely wrapped and fixed. This structurally prevents the leads from deforming or breaking due to vibration or drops, completely eliminates the risk of short circuits or open circuits in the temperature sensor, and significantly improves the reliability of temperature sensing.

[0032] 4) By setting multi-level limiting step surfaces and controllable assembly gaps in the outer shell, or by simultaneously cooperating with buffer pad structures, graded limiting and stress buffering are achieved during the assembly process, avoiding stress concentration and cracking of the pressure sensor chip when it is under pressure during assembly, thus ensuring chip integrity and pressure detection accuracy.

[0033] 5) The NTC protection ring is integrally molded with the housing, and a notch is opened on the side of the protection ring to eliminate the risk of the protection ring falling off, effectively prevent the temperature sensor from being damaged by external force, further improve the overall reliability of the sensor and reduce manufacturing costs.

[0034] 6) The overall structure and manufacturing process of this invention are simple and controllable. The process parameters for injection molding, welding, riveting, high-temperature aging, and silicone curing are clear, resulting in good product consistency, high production efficiency, and meeting IP67 and IP69K protection requirements. It is suitable for mass automated production. Attached Figure Description

[0035] Figure 1 This is a cross-sectional view of the present invention. Figure 2This is a schematic diagram of the temperature sensor assembly in this invention. Figure 3 This is a schematic diagram of the pressure sensor chip in this invention. Figure 4 for Figure 3 Cross-sectional view of the medium pressure sensor chip Figure 5 This is a flowchart of the manufacturing method in the present invention. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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).”

[0040] 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.

[0041] like Figures 1 to 4 As shown, a pressure-temperature combined sensor of the present invention includes a pressure sensor chip 1, an inner sealing ring 2, a housing 3, a temperature sensor assembly 4, an FPCA circuit board 5, a connector 6, and an outer sealing ring 7.

[0042] like Figure 3 and Figure 4 The pressure sensor chip 1 and the housing 3 are sealed once by an inner sealing ring 2; the outer sealing ring 7 is located outside the housing 3; the metal terminal 42 of the temperature sensor assembly 4 is connected to the NTC PIN pin 14 at the bottom of the pressure sensor chip 1 by resistance welding; the temperature sensor assembly 4 is integrated into an injection molded structure after being connected to the NTC lead 412 by resistance welding through the terminal 42, and is provided with an open liquid-tight temperature channel.

[0043] In this embodiment, the pressure sensor chip 1 has a ceramic substrate 12 on its upper surface and a ceramic diaphragm 11 on its lower surface. The ceramic diaphragm 11 and the ceramic substrate 12 are sintered at a high temperature of 600℃~800℃ by sealing with a glass 16. The ceramic substrate 12 on the upper surface has multiple signal output pins 15. The ceramic diaphragm 11 on the lower surface has multiple NTC pins 14. An electrode cavity 13 is provided in the upper middle part of the ceramic diaphragm 11.

[0044] The pressure sensor chip 1 in this embodiment mainly adopts two working principles: piezoresistive and piezoresistive. The piezoresistive type is a variable-gap parallel capacitor, which is composed of a thicker ceramic base 12, a signal output PIN pin 15, a parallel gold electrode cavity 13, a thinner ceramic diaphragm 11, a sealing glass 16, and an NTC PIN pin 14. The ceramic diaphragm 11 senses pressure and undergoes corresponding displacement, i.e., pressure → displacement. The gold electrodes are silkscreened on the ceramic diaphragm 11 and the ceramic base 12, forming a parallel plate capacitor in pairs, which converts pressure into a capacitance signal, i.e., displacement → capacitance.

[0045] In this embodiment, there are three signal output pins 15: a power pin, a signal pin, and a ground pin. They pass through three holes in the ceramic substrate 12. The ceramic diaphragm 11 and the ceramic substrate 12 are sealed by high-temperature sintering with glass. The NTC pin 14 is made of stainless steel, with two pins passing through holes in the ceramic substrate 12 and the ceramic diaphragm 11. Both sides of the NTC pin 14 are perforated. The ceramic diaphragm 11 side is connected to the temperature sensor assembly 4, and the ceramic substrate 12 side is connected to the FPCA circuit board 5.

[0046] like Figure 2 As shown, the temperature sensor assembly 4 in this embodiment includes an NTC thermistor 41, a metal terminal 42, and an injection-molded plastic body 432; the NTC thermistor 41 includes an NTC thermistor chip 41 and an NTC lead 412, and is externally wrapped with epoxy resin with a thickness of 0.1mm~1mm; the NTC lead 412 is a Cu-Ni alloy wire, which is resistively welded to the metal terminal 42 and then integrally injection molded and wrapped.

[0047] In this embodiment, the temperature sensor assembly 4, NTC lead 412 and NTC terminal 42 are resist-welded and then integrally injection molded, which can better prevent the NTC lead 412 from deforming or breaking when vibrating or falling. The NTC lead 412 is coated with epoxy glue for curing insulation treatment at the demolding gap, which can effectively avoid the risk of short circuit or short circuit of NTC thermistor 41 and provide the reliability of NTC thermistor 41.

[0048] In this embodiment, the metal terminal 42 is made of phosphor bronze with a tin plating thickness of 1μm to 6μm; the injection-molded plastic body 432 is made of PPE+PA or PEI material; and the demolding gap of the NTC lead 412 is coated with epoxy resin with a thickness of 0.05mm to 0.5mm.

[0049] In this embodiment, the injection-molded plastic body 432 is provided with a glue storage tank 433 and a plastic boss 431; the glue storage tank 433 is filled with epoxy resin, which wraps the welding part of the temperature sensor assembly 4 and the pressure sensor chip 1 and the exposed metal part. After the epoxy resin is cured at high temperature, it plays an insulating role.

[0050] Preferably, the outer casing 3 is provided with a first stepped surface 31, a second stepped surface 32, a third stepped surface 33, an outer casing groove 34, a through hole inner ring 35, and an NTC protective ring 36; the inner sealing ring 2 is installed in the groove 34, and the height of the groove 34 is 0.5mm~1.5mm; the outer sealing ring 7 is located above the through hole inner ring 35.

[0051] Furthermore, the housing 3 and the connector 6 are fixed by riveting. The connector 6 has a terminal 61 inside. The end face 62 of the connector 6 supports and limits the first stepped surface 31 of the housing, with a gap a=0mm. The gap b between the second stepped surface 32 of the housing and the bottom of the pressure sensor chip 1 is 0.2mm~0.5mm. The gap c between the third stepped surface 33 of the housing and the plastic boss of the temperature sensor assembly 4 is 0.1mm~0.3mm. The gaps satisfy b>c>a=0. Alternatively, a buffer pad can be set at the gap b.

[0052] Furthermore, the NTC protection ring 36 is integrally formed with the housing 3, and a notch 37 is formed on the side. The top of the notch 37 blocks the NTC thermistor 41 to prevent the NTC thermistor 41 from being damaged by the outside. The NTC protection ring 36 can be set as an integral structure with the housing 3 to reduce manufacturing costs, or it can be set as a plastic protection ring and snapped and fixed with the temperature sensor assembly 4 to improve the reliability of the NTC thermistor 41.

[0053] The open-type liquid-tight temperature channel is of type I, formed by the temperature sensor assembly 4, the inner ring 35 of the outer shell through hole, the inner sealing ring 2, and the bottom of the pressure sensor chip 1. An open-type liquid-tight pressure channel is formed by the combination of the internal fluid pressure channel and the external fluid pressure channel, and its shape is L-shaped. The pressure channel and the temperature channel are not parallel to each other. The pressure open-type liquid-tight channel adopts a sealing scheme with one inner sealing ring, which has a better sealing effect than the two inner sealing rings of mainstream products on the market.

[0054] like Figure 5 This embodiment also provides a method for manufacturing a pressure-temperature combined sensor, characterized by comprising the following steps: S1: First, the NTC leads of the temperature sensor assembly are resistively soldered to the metal terminal, and then the assembly is injection molded as a whole. Epoxy resin is applied to the demolding gap for curing and insulation.

[0055] In step S1, the metal terminals of the temperature sensor assembly are made of phosphor bronze, formed by stamping, and tin-plated with 0.5~6μm on the surface. They are then resistively soldered to the NTC leads. The plastic material is either PPE+PA or PEI. During injection molding, the plastic particles are dried at a temperature of 95℃~105℃ for 3~4 hours, and the mold temperature is set at 80℃~120℃. Alternatively, the plastic particles are dried at a temperature of 150℃ for 4~6 hours, and the mold temperature is set at 140℃~180℃.

[0056] Furthermore, when the NTC lead and terminal resistance-welded semi-finished product are integrally injection molded, a gap of 0.2~1.5mm is left at the end of the NTC lead. The mold insert clamps the NTC lead through this gap, which facilitates demolding. The other parts of the NTC lead, the resistance-welded area, and the terminal are integrally wrapped to prevent the NTC lead from deforming or breaking due to vibration or drops. After integral injection molding, the demolding gap of the temperature sensor assembly lead is treated with epoxy resin for insulation. The thickness of the epoxy resin is controlled at 0.05~0.5mm to avoid the risk of short circuit or open circuit of the temperature sensor and to meet the insulation withstand voltage requirements of the temperature sensor.

[0057] The NTC thermistor of the temperature sensor assembly in step S1 includes an NTC thermistor chip and NTC leads, and is coated with an epoxy resin with a coating thickness of 0.1~1mm. The NTC chip of the temperature sensor 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, it is plated with electrodes of either Au or Ag. The NTC lead material is Cu-Ni alloy wire.

[0058] S2: The metal terminals of the temperature sensor assembly are resistively soldered to the NTC pins of the pressure sensor chip, and epoxy resin is applied to the soldered area and the exposed metal for curing and insulation.

[0059] The pressure sensor chip in step S2 mainly has two working principles: piezoresistive and piezoresistive. The piezoresistive type is a variable-gap parallel capacitor, which is composed of a thick ceramic substrate, a signal output PIN, a parallel gold electrode cavity, a thin ceramic diaphragm, a sealing glass, and an NTC PIN.

[0060] The ceramic diaphragm senses pressure and undergoes a corresponding displacement (pressure → displacement). Gold electrodes are silkscreened on the ceramic diaphragm and ceramic base, forming a parallel plate capacitor in pairs. This capacitor converts pressure into a capacitance signal (displacement → capacitance). The capacitance value is calculated using the formula: C = εS / 4πkd, where: C: capacitance value, ε: dielectric constant of the medium between the plates, S: area of ​​the upper and lower plates facing each other, k: electrostatic constant, d: distance between the upper and lower plates. The signal output PIN outputs the capacitance signal to the FPCA circuit board.

[0061] Furthermore, there are three signal output pins: a power pin, a signal pin, and a ground pin. These pins pass through three holes in the ceramic substrate. The ceramic diaphragm and the ceramic substrate are sintered at high temperature using sealed glass, with the sintering temperature controlled between 600℃ and 800℃. The NTC pins are made of stainless steel. Two pins pass through holes in the ceramic substrate and the ceramic diaphragm. The NTC pins are also through holes. The ceramic diaphragm side connects to the NTC, and the ceramic substrate side connects to the FPCA circuit board.

[0062] The manufacturing method of the pressure sensor chip described in this embodiment is as follows: First, the ceramic substrate and ceramic film are formed and drilled → gold electrode printing → sealing glass glue is applied → sintering → glue dispensing → PIN insertion → high temperature curing → capacitance testing, and the sintering temperature is controlled at 600℃~800℃. In this embodiment, the temperature sensor assembly is provided with an epoxy resin reservoir coated with epoxy resin. The resin covers the temperature sensor assembly and the resistance solder joint of the pressure sensor chip, as well as the exposed metal parts. After the epoxy resin cures at high temperature, it provides insulation.

[0063] S3: Further, the FPCA circuit board is prepared by SMT assembly and pressure signal conditioning chips and passive components are installed.

[0064] In step S3, the FPCA circuit board is made of PI material with a thickness of 0.1~0.15mm. The signal conditioning chip is calibrated through a combination of multiple pressure points and multiple temperature points. It converts the received capacitance or resistance value of the pressure sensor chip into a voltage signal, a Sent signal, or a LIN protocol signal, which can reduce temperature drift and improve pressure output accuracy.

[0065] S4: Solder the PIN pins and connector terminals of the pressure sensor chip to the FPCA circuit board to form a semi-finished product.

[0066] In step S4, the connector 6 has a metal terminal made of phosphor bronze, which is formed by stamping and tin-plated on the surface with a thickness of 0.5~6μm. The plastic material is either PPE+PA or PEI, which is formed by injection molding.

[0067] S5: Prepare the outer shell and inner sealing ring, install the inner sealing ring into the groove of the outer shell, install the semi-finished product from step S4 into the inner cavity of the outer shell, and rivet the outer shell to the connector to fix it.

[0068] The inner sealing ring in step S5 is made of HNBR with a hardness of Shore A 70~90, is resistant to cold media, and has a temperature resistance of -40℃~150℃. The inner sealing ring wire diameter is set to φ1.5~φ2mm. The outer shell material is one of aluminum alloy, copper, or stainless steel. The outer shell is provided with grooves with a groove height of 0.5~1.5mm. The outer shell is provided with a riveting support limiting step surface. After riveting, the inner sealing ring is compressed and deformed to achieve the sealing function.

[0069] S6: Perform high-temperature aging stress relief on the finished product from S5 above, with the temperature controlled at 100℃~150℃ and the action time being 1~5h; after the high-temperature aging is completed, apply adhesive to the riveted parts of the finished product for curing and sealing.

[0070] The adhesive used in step S6 is silicone or other adhesives that cure at room temperature. After surface drying for 10 minutes to 1 hour, the product can be used for turnover and testing, which can shorten the curing and placement time of the product and meet IP67 and IP69K requirements.

[0071] S7: Finally, install the cured finished product with the outer sealing ring to complete the entire manufacturing process.

[0072] Compared with the prior art, the present invention has the following significant advantages: 1) This invention adopts a single-seal structure for pressure sensors to replace the traditional secondary seal, which effectively simplifies the assembly process, reduces the number of parts, significantly reduces material and manufacturing costs, and at the same time significantly improves the pressure sealing effect and sealing reliability, thus preventing media leakage.

[0073] 2) The temperature sensor is set as an open liquid-tight channel structure, which greatly shortens the heat conduction path, reduces thermal resistance, and effectively improves the response speed of the temperature sensor. It can quickly and accurately reflect the real-time temperature of the measured medium and eliminate temperature measurement lag. The flow channel layout of L-shaped pressure open liquid-tight channel and I-shaped temperature open liquid-tight channel is not parallel to each other, which optimizes the fluid flow field, avoids the interference of pressure fluctuations on temperature detection, reduces medium retention and bubble adhesion, and improves the stability and consistency of pressure and temperature detection.

[0074] 3) The temperature sensor leads are welded and then integrally injection molded. Epoxy resin is cured and insulated during the demolding gap, so that the leads and the welded parts are completely wrapped and fixed. This structurally prevents the leads from deforming or breaking due to vibration or drops, completely eliminates the risk of short circuits or open circuits in the temperature sensor, and significantly improves the reliability of temperature sensing.

[0075] 4) By setting multi-level limiting step surfaces and controllable assembly gaps in the outer shell, or by simultaneously cooperating with buffer pad structures, graded limiting and stress buffering are achieved during the assembly process, avoiding stress concentration and cracking of the pressure sensor chip when it is under pressure during assembly, thus ensuring chip integrity and pressure detection accuracy.

[0076] 5) The NTC protection ring is integrally molded with the housing, and a notch is opened on the side of the protection ring to eliminate the risk of the protection ring falling off, effectively prevent the temperature sensor from being damaged by external force, further improve the overall reliability of the sensor and reduce manufacturing costs.

[0077] 6) The overall structure and manufacturing process of this invention are simple and controllable. The process parameters for injection molding, welding, riveting, high-temperature aging, and silicone curing are clear, resulting in good product consistency, high production efficiency, and meeting IP67 and IP69K protection requirements. It is suitable for mass automated production.

[0078] 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. A pressure-temperature combined sensor, comprising a pressure sensor chip, a housing, a temperature sensor assembly, an FPCA circuit board, an inner sealing ring, a connector, and an outer sealing ring; characterized in that: The pressure sensor chip and the housing are sealed once by an inner sealing ring; the outer sealing ring is located outside the housing; the metal terminal of the temperature sensor assembly is connected to the NTC PIN at the bottom of the pressure sensor chip by resistance welding; the temperature sensor assembly is integrally injection molded after being connected to the NTC lead by resistance welding through the metal terminal and the NTC lead, and is provided with an open liquid-tight temperature channel.

2. The pressure-temperature combined sensor according to claim 1, characterized in that: The pressure sensor chip has a ceramic base on its upper surface and a ceramic diaphragm on its lower surface. The ceramic diaphragm and the ceramic base are sintered at a high temperature of 600℃~800℃ through a sealing glass. The ceramic base on the upper surface has multiple signal output pins. The ceramic diaphragm on the lower surface has multiple NTC pins. An electrode cavity is located in the upper middle part of the ceramic diaphragm. The NTC pin is made of stainless steel, passes through the ceramic base and the ceramic diaphragm, and protrudes from both sides; there are three signal output pins, namely the power pin, the signal pin, and the ground pin.

3. The pressure-temperature combined sensor according to claim 1, characterized in that: The temperature sensor assembly includes an NTC thermistor, metal terminals, and an injection-molded plastic body; the NTC thermistor comprises an NTC thermistor chip and NTC leads, and is externally wrapped with epoxy resin with a thickness of 0.1mm~1mm; the NTC leads are Cu-Ni alloy wires, which are welded to the metal terminal resistors and then integrally injection molded and wrapped.

4. The pressure-temperature combined sensor according to claim 3, characterized in that: The metal terminal is made of phosphor bronze with a tin plating thickness of 0.5μm to 6μm; the injection-molded plastic body is made of PPE+PA or PEI material; the demolding gap of the NTC lead is coated with epoxy resin with a thickness of 0.05mm to 0.5mm. The injection-molded plastic body is provided with a glue storage tank and plastic bosses; the glue storage tank is filled with epoxy resin to cover the welding parts of the temperature sensor assembly and the pressure sensor chip, as well as the exposed metal parts.

5. The pressure-temperature combined sensor according to claim 1, characterized in that: The outer casing is provided with a groove, a first stepped surface, a second stepped surface, a third stepped surface, a through-hole inner ring, and an NTC protective ring; the inner sealing ring is installed in the groove, and the groove height is 0.5mm~1.5mm; The housing and connector are fixed by riveting. The end face of the connector is supported and limited by the first stepped surface of the housing, with a gap a=0mm. The gap b between the second stepped surface of the housing and the bottom of the pressure sensor chip is 0.2mm~0.5mm. The gap c between the third stepped surface of the housing and the plastic boss of the temperature sensor assembly is 0.1mm~0.3mm. The gaps satisfy b>c>a=0. Alternatively, a buffer pad can be set at the gap b. The NTC protection ring is integrally formed with the outer shell, and a notch is formed on the side; the top of the notch covers the NTC thermistor.

6. The pressure-temperature combined sensor according to claim 5, characterized in that: The open-type liquid-tight temperature channel is of type I, and is formed by the temperature sensor assembly, the inner ring of the outer shell through hole, the inner sealing ring and the bottom of the pressure sensor chip; the open-type liquid-tight pressure channel is formed by the combination of the internal fluid pressure channel and the external fluid pressure channel, and its shape is L; the pressure channel and the temperature channel are not parallel to each other.

7. A method for manufacturing a pressure-temperature combined sensor, characterized in that, Includes the following steps: S1: First, the NTC lead of the temperature sensor assembly is resistively soldered to the metal terminal, and then it is integrally injection molded. Epoxy resin is applied to the demolding gap for curing and insulation. S2: The metal terminals of the temperature sensor assembly are soldered to the NTC pins of the pressure sensor chip by resistance welding. Epoxy resin is then applied to the soldered areas and exposed metal for curing and insulation. S3: Further, prepare the FPCA circuit board by SMT assembly and install the pressure signal conditioning chip and passive components. S4: Solder the PIN pins and connector terminals of the pressure sensor chip to the FPCA circuit board to form a semi-finished product; S5: Prepare the outer shell and inner sealing ring, install the inner sealing ring into the groove of the outer shell, install the semi-finished product from step S4 into the inner cavity of the outer shell, and rivet the outer shell and connector to fix them. S6: The finished product in S5 above is subjected to high-temperature aging to relieve stress. The temperature is controlled at 100℃~150℃ and the action time is 1~5h. After the high-temperature aging is completed, the riveted parts of the finished product are coated with glue for curing and sealing. S7: Finally, install the cured finished product with the outer sealing ring to complete the entire manufacturing process.

8. The manufacturing method according to claim 7, characterized in that: In step S1, the metal terminals of the temperature sensor assembly are made of phosphor bronze, formed by stamping, and tin-plated to a thickness of 0.5~6μm. They are then resistively soldered to the NTC leads. The plastic material used is PPE+PA or PEI. For one type of material, during injection molding, the plastic particle drying temperature is 95℃~105℃, the drying time is 3~4h, and the mold temperature is set at 80℃~120℃; or the plastic particle drying temperature is 150℃, the drying time is 4~6h, and the mold temperature is set at 140℃~180℃. When the NTC lead and terminal resistance welding semi-finished product are integrally injection molded, a gap of 0.2~1.5mm is left at the end of the NTC lead. The mold insert clamps the NTC lead through this gap to facilitate demolding. Other parts of the NTC lead, the resistance welding area, and the terminal are wrapped by integral injection molding to prevent the NTC lead from deforming or breaking due to vibration or falling. Epoxy resin is applied to the demolding gap of the integrally injection molded temperature sensor assembly lead for insulation. The thickness of the epoxy resin is controlled at 0.05~0.5mm to avoid the risk of short circuit or open circuit of the temperature sensor and to meet the insulation withstand voltage requirements of the temperature sensor. The NTC thermistor of the temperature sensor assembly in step S1 includes an NTC thermistor chip and NTC leads, and is coated with an epoxy resin with a coating thickness of 0.1~1mm. The NTC chip of the temperature sensor 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, it is plated with electrodes of either Au or Ag. The NTC lead material is Cu-Ni alloy wire.

9. The manufacturing method according to claim 7, characterized in that: The pressure sensor chip in step S2 mainly has two working principles: piezoresistive and piezoresistive. The piezoresistive type is a variable-gap parallel capacitor, which is composed of a thick ceramic substrate, a signal output PIN, a parallel gold electrode cavity, a thin ceramic diaphragm, a sealing glass, and an NTC PIN. In this process, a ceramic diaphragm senses pressure and undergoes corresponding displacement. Gold electrodes are silkscreened on the ceramic diaphragm and ceramic base, forming a parallel plate capacitor in pairs. The pressure is converted into a capacitance signal (displacement → capacitance). The capacitance value is calculated using the formula: C = εS / 4πkd, where: C: capacitance value, ε: dielectric constant of the medium between the plates, S: area of ​​the upper and lower plates facing each other, k: electrostatic constant, d: distance between the upper and lower plates. The signal output PIN outputs the capacitance signal to the FPCA circuit board. There are three signal output pins: power pin, signal pin, and ground pin. They pass through three holes in the ceramic substrate. The ceramic diaphragm and the ceramic substrate are sintered at high temperature with sealed glass, and the sintering temperature is controlled at 600℃~800℃. The NTC pin is made of stainless steel. Two pins pass through holes in the ceramic substrate and the ceramic diaphragm. The NTC pin has holes on both sides. The ceramic diaphragm side is connected to the NTC, and the ceramic substrate side is connected to the FPCA. The manufacturing method of the pressure sensor chip is as follows: First, the ceramic substrate and ceramic film are formed and drilled → gold electrode printing → sealing glass glue is applied → sintering → glue dispensing → PIN insertion → high temperature curing → capacitance testing, and the sintering temperature is controlled at 600℃~800℃. The temperature sensor assembly is provided with an epoxy resin tank coated with epoxy resin. The amount of resin covers the temperature sensor assembly and the resistance solder joint of the pressure sensor chip, as well as the exposed metal parts. After the epoxy resin is cured at high temperature, it provides insulation. The FPC material of the FPCA circuit board in step S3 is PI, with a thickness of 0.1~0.15mm. The signal conditioning chip is calibrated through multiple pressure points + multiple temperature points, converting the received capacitance or resistance value of the pressure sensor chip into a voltage signal, a Sent signal, or a LIN protocol signal, which can reduce temperature drift and improve pressure output accuracy. In step S4, connector 6 and metal terminals are made of phosphor bronze material, formed by stamping, and tin-plated on the surface with a thickness of 0.5~6μm. Plastic material is either PPE+PA or PEI material, formed by injection molding. The inner sealing ring in step S5 is made of HNBR with a hardness of Shore A 70~90, is resistant to cold media, and has a temperature resistance of -40℃~150℃. The inner sealing ring wire diameter is set to φ1.5~φ2mm. The outer shell material is one of aluminum alloy, copper, or stainless steel. The outer shell is provided with grooves with a groove height of 0.5~1.5mm. The outer shell is provided with a riveting support limiting step surface. After riveting, the inner sealing ring is compressed and deformed to achieve the sealing function.

10. The manufacturing method according to claim 7, characterized in that: The inner sealing ring in step S5 is made of HNBR with a Shore A hardness of 70-90, is resistant to cold media, and has a temperature resistance of -40℃ to 150℃. The inner sealing ring wire diameter is set to φ1.5-φ2mm. The outer shell material is one of aluminum alloy, copper, or stainless steel. The outer shell has grooves with a groove height of 0.5-1.5mm. The outer shell has a riveting support limiting step surface. After riveting, the inner sealing ring is compressed and deformed to achieve the sealing function. The adhesive in step S6 is silicone or other adhesives that cure at room temperature. It can be used for turnover and testing after 10 minutes to 1 hour of surface drying, which can shorten the product curing and placement time and meet IP67 and IP69K requirements.

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