Thin-film resistor temperature sensor and preparation method thereof
By using a front-back separated lead layout and a fully sealed glass package, the problems of poor contact and insufficient protection in traditional thin-film resistance temperature sensors are solved, thereby improving the stability and measurement accuracy of the sensor.
Patent Information
- Application Number
- CN202511894476.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-02-13
AI Technical Summary
Traditional thin-film resistance temperature sensors suffer from poor contact due to the parallel axial design of the leads, and the non-fully encapsulated design results in insufficient protection, affecting measurement accuracy and stability.
It adopts a front and back separated lead layout and a fully sealed glass shell package. The electrical signal transfer is realized through the conductive dielectric layer, and the leads are brought out on the back and front of the substrate respectively. Combined with the glass shell, it provides fully sealed protection.
The increased contact area between the leads and electrodes improves the tensile strength and installation stability of the leads, isolates external contaminants, and enhances the long-term stability and measurement accuracy of the sensor.
Smart Images
Figure CN121521291A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sensor technology, specifically a thin-film resistance temperature sensor and its fabrication method. Background Technology
[0002] Resistance temperature sensors made from metallic materials possess excellent physicochemical properties, offering advantages such as small size, high accuracy, fast response, and good long-term stability. Platinum resistance temperature sensors, utilizing the resistance-temperature characteristics of platinum, offer high accuracy, easy signal detection, and good stability, making them widely applicable. Traditional wire-wound platinum resistance temperature sensors use platinum wire as the temperature-sensitive material, requiring a large amount of platinum and incurring high costs; they have been gradually replaced by thin-film platinum resistance temperature sensors. With the widespread application of thin-film resistance temperature sensors, their traditional axial dual-parallel lead design and non-fully encapsulated packaging methods have gradually revealed some drawbacks during use. For example, traditional leads are typically drawn side-by-side from the same side (usually the side or end face) of the sensor chip. This design limits the contact area between each lead and the internal electrodes, resulting in mostly point contact or small-area line contact. This results in a small contact area between the leads and electrodes, leading to lower lead pull. Under certain installation conditions (such as crimping or plugging) or operating environments (such as continuous vibration or thermal cycling), this can cause poor contact between the leads and the thermistor electrode area, introducing additional resistance and even causing signal interruption, severely impacting the sensor's measurement accuracy and reliability. On the other hand, traditional packaging is often partial (such as applying adhesive or covering the sensitive area with a protective cap) or non-hermetic, failing to completely isolate the sensor chip from the external environment. When the operating environment contains corrosive liquids or gases (such as acidic or alkaline media, or high-humidity air) or is subjected to long-term vibration, harmful substances may penetrate the sensor, corroding the thin-film resistor, electrodes, or lead contacts. Simultaneously, mechanical stress may cause the package shell to separate from the sensor chip, losing its protective function. These defects can cause inaccuracies, performance degradation, or even premature failure of thin-film resistance temperature sensors. Therefore, there is an urgent need to improve the lead connection structure and overall packaging of thin-film resistance temperature sensors to enhance their environmental adaptability, mechanical stability, and long-term measurement accuracy. Summary of the Invention
[0003] The technical problem solved by this invention is to provide a thin-film resistance temperature sensor and its preparation method, which solves the problem of poor contact and inaccurate sensor accuracy caused by the parallel axial design of the leads in current temperature sensors. It also solves the problem of insufficient protection for temperature sensors caused by the non-fully encapsulated packaging structure, thereby improving the stability of the sensor.
[0004] The technical solution of this invention is: The present invention provides a thin-film resistance temperature sensor, comprising: Base, A thin-film resistor, wherein the thin-film resistor is disposed on the front side of a substrate, and includes a resistive region, a first electrode region, and a second electrode region; An insulating protective layer that covers the resistive region of the thin-film resistor; A first conductive dielectric layer is connected to the first electrode region of the thin film resistor and guides the electrical signal of the first electrode region of the thin film resistor to the back side of the substrate. The first lead extends from the first conductive dielectric layer on the back side of the substrate; The second lead extends from the second electrode region of the thin-film resistor on the front side of the substrate.
[0005] The present invention also provides a thin-film resistance temperature sensor, comprising: Base, A thin-film resistor, wherein the thin-film resistor is disposed on the front side of a substrate, and includes a resistive region, a first electrode region, and a second electrode region; An insulating protective layer that covers the resistive region of the thin-film resistor; A first conductive dielectric layer is connected to the first electrode region of the thin film resistor and guides the electrical signal of the first electrode region of the thin film resistor to the back side of the substrate. The second conductive dielectric layer is located on the front side of the substrate, covering the second electrode region of the thin film resistor and a portion of the insulating protective layer, but not covering the first electrode region of the thin film resistor. The first lead extends from the first conductive dielectric layer on the back side of the substrate; The second lead extends from the second conductive dielectric layer on the front side of the substrate.
[0006] Furthermore, the sensor also includes a packaging shell for encapsulating the thin-film resistance temperature sensor chip formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, second conductive dielectric layer, first lead, and second lead.
[0007] Furthermore, the material of the encapsulation shell can be glass, epoxy resin, ceramic, etc.
[0008] Preferably, the encapsulation shell is made of glass.
[0009] Preferably, the first lead extends from the middle of the first conductive dielectric layer on the back side of the substrate, and the second lead extends from the middle of the second conductive dielectric layer on the front side of the substrate.
[0010] Furthermore, the substrate is made of alumina ceramic, alumina single crystal, silicon nitride ceramic, silicon nitride single crystal, or zirconium oxide ceramic. The thin-film resistor is a thermistor, and the thin-film material of the thermistor is platinum, copper, or nickel. The insulating protective layer is made of alumina film, alumina ceramic sheet, or glass paste. The first conductive dielectric layer and the second conductive dielectric layer are made of silver, copper, gold or tin.
[0011] The present invention provides a method for fabricating a thin-film resistance temperature sensor, comprising the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography. S2 covers the resistive region of the thin-film resistor with an insulating protective layer; S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate. S4 A first lead is drawn from the first conductive dielectric layer on the back side of the substrate, and a second lead is drawn from the second electrode region on the front side of the substrate; S5 The thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, first lead and second lead together, is radially placed inside the package shell and sintered under inert gas protection to form a fully sealed package.
[0012] This invention also provides a method for fabricating a thin-film resistance temperature sensor, comprising the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography. S2 covers the resistive region of the thin-film resistor with an insulating protective layer; S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate. A second conductive dielectric layer is formed on the front side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing. The second conductive dielectric layer covers the second electrode region of the thin film resistor and a portion of the insulating protective layer, but does not cover the first electrode region of the thin film resistor. S4 extends a first lead from the first conductive dielectric layer on the back side of the substrate and extends a second lead from the second conductive dielectric layer on the front side of the substrate.
[0013] Furthermore, the preparation method further includes: S5 The thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, second conductive dielectric layer, first lead and second lead together, is radially placed inside the package shell and sintered under inert gas protection to form a fully sealed package.
[0014] Furthermore, in step S3, the first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate, specifically as follows: The first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate by sputtering or coating a conductive dielectric at the side end; or... A via is formed on the substrate and a conductive medium is filled in the via to connect the first electrode region of the thin film resistor on the front side of the substrate to the first conductive medium layer on the back side of the substrate.
[0015] Preferably, in step S4, the first lead is drawn from the middle of the first conductive dielectric layer on the back side of the substrate, and the second lead is drawn from the middle of the second conductive dielectric layer on the front side of the substrate.
[0016] Furthermore, in step S4, the first lead is led out from the first conductive dielectric layer on the back side of the substrate through platinum paste or silver paste, and the second lead is led out from the second conductive dielectric layer on the front side of the substrate through platinum paste or silver paste. Alternatively, the first lead is led out from the first conductive dielectric layer on the back side of the substrate by soldering, and the second lead is led out from the second conductive dielectric layer on the front side of the substrate by soldering.
[0017] Preferably, in step S5, the thin-film resistance temperature sensor chip is radially placed inside the glass housing, and the glass is sintered under inert gas protection to form a fully sealed glass package.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention involves leading a first lead from the first conductive dielectric layer on the back side of the substrate and a second lead from the second conductive dielectric layer on the front side of the substrate. This "front-back separation" lead layout fundamentally avoids the short-circuit risk that may be caused by the close spacing of traditional parallel leads and provides space to increase the connection area of a single lead. When both leads are led out from the middle of the conductive dielectric layer, the contact area between the lead and the electrode is the largest. Therefore, it is preferable to lead the first lead out from the middle of the first conductive dielectric layer and the second lead out from the middle of the second conductive dielectric layer. This method increases the contact area between the electrode and the lead, improves the tensile strength of the lead, and further improves the reliability of the lead electrical connection. The two leads are parallel to each other and are located on the two largest surfaces of the sensor chip, forming a stable "radial double parallel line" structure, which is very easy to center and fix in the mounting hole or connector, and has good installation stability.
[0019] (2) The present invention uses a fully sealed glass shell for encapsulation. The glass material has excellent chemical stability, insulation and airtightness, which can effectively isolate the thin film resistor from external pollutants (such as moisture, oxygen, salt spray and corrosive gas) for a long time. At the same time, it can also buffer some external mechanical stress and enhance the long-term stability of the sensor.
[0020] (3) The materials of each layer of the present invention support each other structurally and are coupled to each other functionally, thereby protecting the thin film resistance temperature sensor chip. The substrate provides mechanical support and thermal conduction, the thin film resistor realizes temperature sensing, the insulating protective layer performs local segmentation and protection, the first conductive dielectric layer realizes the spatial transfer of electrical signals, the second conductive dielectric layer expands the contact area between the second lead and the second electrode, and the glass shell provides ultimate environmental protection, forming an organic multi-layer protection system. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a schematic diagram of a thin-film resistance temperature sensor provided in Embodiment 1 of the present invention.
[0023] Figure 2 for Figure 1 A schematic diagram showing the exploded structure of a thin-film resistance temperature sensor.
[0024] Figure 3 This is a schematic diagram of a thin-film resistor.
[0025] Figure 4 This is a schematic diagram of a thin-film resistance temperature sensor provided in Embodiment 2 of the present invention.
[0026] Figure 5 for Figure 4 A schematic diagram showing the exploded structure of a thin-film resistance temperature sensor.
[0027] Figure 6 This is a schematic diagram of a thin-film resistance temperature sensor provided in Embodiment 3 of the present invention.
[0028] Figure 7 for Figure 6 A schematic diagram showing the exploded structure of a thin-film resistance temperature sensor.
[0029] Figure 8 This is a front view of the thin-film resistance temperature sensor chip (semi-finished product) in an embodiment of the present invention before sintering inside a glass shell.
[0030] Figure 9 This is a front view of the thin-film resistance temperature sensor chip of an embodiment of the present invention after it is placed inside a glass housing and sintered (finished product).
[0031] Figure 10 This is a flowchart illustrating a method for fabricating a thin-film resistance temperature sensor according to an embodiment of the present invention.
[0032] Figure 11 A flowchart illustrating another method for fabricating a thin-film resistance temperature sensor provided in an embodiment of the present invention.
[0033] The meanings of the labels in the attached diagram are as follows: 1-Substrate; 2-Thin film resistor; 3-Insulating protective layer; 4-First conductive dielectric layer; 5-Second conductive dielectric layer; 6-First lead; 7-Second lead; 8-Thin film resistor temperature sensor chip; 9-Glass housing; 21-Resistance region of thin film resistor; 22-First electrode region of thin film resistor; 23-Second electrode region of thin film resistor. Detailed Implementation
[0034] 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, and 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.
[0035] Example 1 Please see Figure 1 and Figure 2The thin-film resistance temperature sensor provided in Embodiment 1 of the present invention includes a substrate 1, a thin-film resistor 2, an insulating protective layer 3, a first conductive dielectric layer 4, a first lead 6, and a second lead 7, which together constitute a thin-film resistance temperature sensor chip 8.
[0036] Among them, such as Figure 3 As shown, the thin-film resistor 2 includes a resistor region 21, a first electrode region 22, and a second electrode region 23. The thin-film resistor 2 is disposed on the front side of the substrate 1.
[0037] An insulating protective layer 3 covers the resistive region 21 of the thin-film resistor.
[0038] The first conductive dielectric layer 4 is connected to the first electrode region 22 of the thin film resistor on the front side of the substrate, and guides the electrical signal of the first electrode region 22 of the thin film resistor to the back side of the substrate 1.
[0039] The first lead 6 extends from the first conductive dielectric layer 4 on the back side of the substrate 1. Preferably, the first lead 6 extends from the middle of the first conductive dielectric layer 4 on the back side of the substrate.
[0040] The second lead 7 extends from the second electrode region 23 of the thin-film resistor on the front side of the substrate 1. Preferably, the second lead 7 extends from the center of the second electrode region 23 of the thin-film resistor on the front side of the substrate.
[0041] Example 2 and Example 3 Please refer to Example 2 Figure 4 and Figure 5 In the second embodiment, the first electrode region of the thin film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate by sputtering or coating a conductive dielectric at the end of the substrate side.
[0042] Please refer to Example 3 Figure 6 and Figure 7 , Figure 6 and Figure 7 Not marked with Figure 4 and Figure 5 The common features include: insulating protective layer 3, second conductive dielectric layer 5, first lead 6, and second lead 7. Embodiment 3 involves forming through-holes on the substrate and filling the through-holes with conductive dielectric to connect the first electrode region of the thin-film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate.
[0043] The thin-film resistance temperature sensor provided in Embodiments 2 and 3 includes a substrate 1, a thin-film resistor 2, an insulating protective layer 3, a first conductive dielectric layer 4, a second conductive dielectric layer 5, a first lead 6, and a second lead 7, which together constitute a thin-film resistance temperature sensor chip 8.
[0044] Among them, such as Figure 3As shown, the thin-film resistor 2 includes a resistor region 21, a first electrode region 22, and a second electrode region 23. The thin-film resistor 2 is disposed on the front side of the substrate 1.
[0045] An insulating protective layer 3 covers the resistive region 21 of the thin-film resistor.
[0046] The first conductive dielectric layer 4 is connected to the first electrode region 22 of the thin film resistor on the front side of the substrate, and guides the electrical signal of the first electrode region 22 of the thin film resistor to the back side of the substrate 1.
[0047] The second conductive dielectric layer 5 is located on the front side of the substrate 1, covering the second electrode region 23 of the thin-film resistor and a portion of the insulating protective layer 3, but not covering the first electrode region 22 of the thin-film resistor. Preferably, the second conductive dielectric layer 5 covers not only the second electrode region 23 of the thin-film resistor, but also most of the insulating protective layer 3, but not the first electrode region 22 of the thin-film resistor.
[0048] The first lead 6 extends from the first conductive dielectric layer 4 on the back side of the substrate 1. Preferably, the first lead 6 extends from the middle of the first conductive dielectric layer 4 on the back side of the substrate.
[0049] The second lead 7 extends from the second conductive dielectric layer 5 on the front side of the substrate 1. Preferably, the second lead 7 extends from the middle of the second conductive dielectric layer 5 on the front side of the substrate.
[0050] It should be noted that in Embodiment 1, the second lead 7 is led out from the second electrode region 23 of the thin film resistor on the front side of the substrate 1.
[0051] In Embodiments 2 and 3, the second lead 7 extends from the second conductive dielectric layer 5 on the front side of the substrate 1. The second conductive dielectric layer 5 is added to increase the contact area between the second lead 7 and the second electrode region 23 of the thin-film resistor on the front side of the substrate. Because the second lead 7 needs to rest on the second electrode region 23 of the thin-film resistor to conduct electrical signals, but the area of the second electrode region 23 is limited, this invention utilizes the second conductive dielectric layer 5 (connected to the second electrode region 23 of the thin-film resistor) to increase the radiation area of the second electrode 23 of the thin-film resistor, thereby increasing the contact area between the second lead 7 and the second electrode 23 of the thin-film resistor on the front side of the substrate. Otherwise, the structure is basically the same as in Embodiment 1.
[0052] The core of the structural design of this invention lies in the adoption of a "double-sided lead" layout, breaking away from the traditional sensor pattern where all leads are led out from the same plane or side. The conductive dielectric layers (first conductive dielectric layer and second conductive dielectric layer) play a crucial role as an "electrical signal transfer channel." The first conductive dielectric layer reliably guides the electrical signal from the first electrode area of the thin-film resistor on the front side of the substrate to the back side of the substrate, thereby creating conditions for connecting the first lead on the back side of the substrate.
[0053] Please see Figure 8 and Figure 9 The thin-film resistance temperature sensor provided in this embodiment of the invention further includes a packaging shell, which is used to encapsulate the thin-film resistance temperature sensor chip 8. In this embodiment, the packaging shell is a glass shell 9. The glass shell completely encapsulates the core sensing element, forming an airtight seal and completely isolating the sensitive element from external environmental corrosion. Using a fully sealed glass shell isolates the thin-film resistor from external contaminants, enhancing the long-term stability of the sensor.
[0054] Figure 8 The relative positions of the thin-film resistance temperature sensor chip 8 and the glass housing 9 are shown, as well as the preliminary arrangement of the leads within the housing. Figure 9 The final form of the glass housing 9, after sintering, tightly wraps the thin-film resistance temperature sensor chip 8, forming a smooth, hermetically sealed package.
[0055] The glass housing 9 is usually a pre-formed tubular or sleeve-shaped structure, and its coefficient of thermal expansion needs to match that of the substrate 1 and the internal materials in order to reduce thermal stress during encapsulation.
[0056] It should be noted that other non-glass materials such as epoxy resin sealant, metal-glass composite encapsulation, and ceramic encapsulation can also be used for the encapsulation shell. However, glass encapsulation is preferred because it is a standard process that can be sintered, softened, and sealed. The process is mature, the cost is controllable, and it can achieve excellent transparent or semi-transparent observation effects (which is convenient for quality inspection).
[0057] In a preferred embodiment of the present invention, the first lead extends from the center of the first conductive dielectric layer on the back side of the substrate, and the second lead extends from the center of the second conductive dielectric layer on the front side of the substrate. If there is no second conductive dielectric layer, the second lead extends from the center of the second electrode region of the thin-film resistor on the front side of the substrate. This "center-out" design maximizes the contact area between a lead and its corresponding electrode (the first electrode region or the second electrode region of the thin-film resistor). Compared to leading from the edge, center-out leads allow the lead (e.g., a metal wire) to form a larger circumferential annular welding or bonding area with the electrode, significantly improving mechanical connection strength and electrical connection reliability.
[0058] The larger the contact area between the lead and the electrode, the better. Specifically, taking the presence of a second conductive dielectric layer as an example, this refers to the contact area between the first lead 6 and the first conductive dielectric layer 4, and the contact area between the second lead 7 and the second conductive dielectric layer 5, since both the first conductive dielectric layer 4 and the second conductive dielectric layer 5 function as electrodes. The contact area between the lead and the electrode is maximized when both leads originate from the middle of the electrode. Therefore, it is preferable to lead the first lead from the middle of the first conductive dielectric layer and the second lead from the middle of the second conductive dielectric layer. The two leads form a radial double-parallel lead structure. Besides facilitating installation, this method increases the contact area between the electrode and the lead, improving the reliability of the lead electrical connection and the lead tensile strength.
[0059] In a specific embodiment of the present invention, the substrate 1 is made of alumina ceramic, alumina single crystal, silicon nitride ceramic, silicon nitride single crystal, or zirconium oxide ceramic. These materials possess excellent insulation, high thermal conductivity, high mechanical strength, and a thermal expansion coefficient that matches well with subsequent thin film materials, making them ideal sensor substrate materials. Among them, alumina ceramic is the most commonly used due to its excellent overall performance and low cost.
[0060] Thin-film resistor 2 is a thermistor, and the thin-film material of the thermistor is platinum, copper, or nickel. Among them, platinum is the first choice for high-precision sensors due to its excellent resistance-temperature linearity, stability, and oxidation resistance; copper and nickel are lower in cost and suitable for cost-sensitive applications. For Pt100 or Pt1000 standard sensors, high-purity platinum thin film must be used.
[0061] The insulating protective layer 3 is made of alumina film, alumina ceramic sheet, or glass paste. Its main function is to physically isolate and protect the thin-film resistive pattern, preventing it from being scratched, contaminated, or chemically reacting with the environment, while maintaining its electrical insulation. Sputter-grown alumina film has the best density and provides the best protective effect.
[0062] The first conductive dielectric layer 4 and the second conductive dielectric layer 5 are made of silver, copper, gold, or tin. These metals have good conductivity, are easy to form through deposition or printing processes, and can form good ohmic contacts or solder joints with lead materials (such as platinum wire, Dummex wire, etc.). Considering the balance between cost and performance, silver paste is the most commonly used conductive dielectric layer and interconnect material.
[0063] The materials in each layer support each other structurally and are coupled functionally to protect the thin-film resistance temperature sensor chip.
[0064] It should be noted that in this manual, the thin-film resistance temperature sensor before being placed in the housing is also called a thin-film resistance temperature sensor chip, and the thin-film resistance temperature sensor placed in the glass housing but before sintering is also called a semi-finished product, and the thin-film resistance temperature sensor placed in the glass housing and sintered is also called a finished product.
[0065] As an embodiment of the present invention, please refer to Figure 1 and Figure 2 Or please see Figure 4 and Figure 5 The first electrode region of the thin film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate by sputtering or coating a conductive dielectric at the end of the substrate side. Figure 1 or Figure 4 The front and back lead structure interconnected via side conductive paths is shown. Figure 2 or Figure 5 The stacking relationship of substrate 1, thin film resistor 2, insulating protective layer 3, side conductive dielectric, first conductive dielectric layer 4, second conductive dielectric layer 5 and two leads (first lead 6 and second lead 7) is clearly shown.
[0066] In practice, a layer of conductive material (such as silver paste) can be deposited or printed first on the edge of the front electrode area and the corresponding area on the back. Then, a layer of metal (such as gold) can be sputtered onto the side face (thickness direction) of the substrate through a mask, or conductive silver paste can be precisely coated using a fine brush to form a conductive bridge connecting the front and back sides. The width and thickness of this conductive bridge must be sufficient to carry the operating current without generating a significant temperature rise.
[0067] The typical dimensions of substrate 1 are 1-3 mm in length, 0.5-2 mm in width, and 0.2-0.5 mm in thickness. The thickness of the thin-film resistor 2 is typically between tens and hundreds of nanometers, and its pattern is designed in a classic meandering shape to increase resistance and improve sensitivity. The insulating protective layer 3 is approximately 0.1-2 mm thick and must completely cover all resistive pattern areas except for the electrode region.
[0068] As another embodiment of the present invention, please refer to Figure 6 and Figure 7 By setting through holes on the substrate and filling the through holes with conductive medium, electrical signals are guided to the back side of the substrate, thereby connecting the first electrode region of the thin film resistor on the front side of the substrate with the first conductive dielectric layer on the back side of the substrate. Figure 6 The front and back lead structure interconnected via through-holes is shown. Figure 7 The details of vertical interconnection achieved by filling through-holes with conductive dielectric are highlighted.
[0069] Through-holes can be formed using laser drilling or mechanical drilling, with a typical diameter of 50-150 micrometers. The conductive medium can be filled by screen printing the conductive paste into the hole, or by electroplating or electroless plating to deposit metal on the hole walls. The filling must be thorough to ensure continuity of conductivity.
[0070] Please see Figure 10 The present invention provides a method for fabricating a thin-film resistance temperature sensor, comprising the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography.
[0071] S2 covers the resistive region of the thin-film resistor with an insulating protective layer.
[0072] S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate.
[0073] S4 leads out a first lead from the first conductive dielectric layer on the back side of the substrate and a second lead from the second electrode region on the front side of the substrate.
[0074] S5 The thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, first lead and second lead together, is radially placed inside the package shell and sintered under inert gas protection to form a fully sealed package.
[0075] Figure 10 This is a flowchart of a sensor fabrication method in which a second lead is directly drawn from the second electrode of a thin-film resistor on the front side of the substrate without setting a second conductive dielectric layer. Figure 11 This is a flowchart illustrating a sensor fabrication method where a second conductive dielectric layer is formed and a second lead is extended from the second conductive dielectric layer on the front side of the substrate. Figure 10 compared to, Figure 11 The main difference is the addition of the step of preparing the second conductive dielectric layer; the other steps are the same. Therefore, the following text will refer to them as such. Figure 11 Taking the example of setting a second conductive dielectric layer, the fabrication method of the sensor will be explained in detail.
[0076] Please see Figure 11 Another method for fabricating a thin-film resistance temperature sensor provided in this embodiment of the invention includes the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography.
[0077] Physical vapor deposition (e.g., magnetron sputtering, evaporation) can form dense, uniform, and strongly adherent thin films; chemical vapor deposition may have advantages in high-volume or complex surface treatments. Photolithography processes (including coating, exposure, development, etching, etc.) can precisely define high-precision thin-film resistance patterns (such as meandering shapes), which is key to achieving high precision and high consistency in sensors.
[0078] Taking platinum sputtering as an example, the process parameters may include: substrate temperature 200-400°C, sputtering pressure 0.5-2 Pa, power 200-500 W, deposition rate approximately 0.1-0.5 nm / s, and final film thickness controlled at 100-500 nm. The photolithography process involves spin-coating photoresist, UV exposure through a mask, development to form a pattern, and finally, ion etching or wet etching to remove the unprotected platinum film, forming the designed resistor pattern.
[0079] S2 covers the resistive region of the thin-film resistor with an insulating protective layer.
[0080] The insulating protective layer protects the covered area. This step requires precise alignment to ensure that the electrode area (i.e., the area that needs to be connected to external circuitry) is exposed, typically achieved through processes such as mask printing, photolithography, or laser ablation.
[0081] In this embodiment, an insulating protective layer is printed on the substrate for all areas except the thin-film resistor electrode regions (first electrode region and second electrode region). Screen printing technology can be used to precisely print alumina paste or glass paste onto the areas requiring protection, followed by low-temperature sintering (600-800°C) to densify it. High-precision alignment equipment is required during printing to ensure clear electrode area windows and neat edges.
[0082] S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate.
[0083] A second conductive dielectric layer is formed on the front side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing. The second conductive dielectric layer covers the second electrode region of the thin film resistor and a portion of the insulating protective layer, but does not cover the first electrode region of the thin film resistor.
[0084] This is a key interconnection step that enables signals to be transferred from the front to the back.
[0085] In Examples 1 and 2, please refer to Figure 1 and Figure 2 Or please see Figure 4 and Figure 5The first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate by sputtering or coating a conductive dielectric. This method is relatively simple, achieving interconnection by forming a conductive path on the sidewall of the substrate, and is suitable for sensors with certain requirements on thickness and volume. During sputtering, multiple substrates can be arranged so that their side faces all face the sputtering target for one-time film formation. For coating, automated dispensing path planning can be used to ensure the consistency of the conductive path on each side face.
[0086] In Example 3, please refer to Figure 6 and Figure 7 By creating vias on the substrate and filling them with a conductive dielectric, the first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate. This method (i.e., forming "vias" for vertical interconnects) enables more direct signal transmission, potentially with lower interconnect resistance and better high-frequency characteristics, but requires additional drilling and filling processes. After via filling, a planarization process (such as grinding or polishing) is usually required to remove excess conductive material from the surface and ensure the flatness of subsequent lead connections.
[0087] S4 extends a first lead from the first conductive dielectric layer on the back side of the substrate and extends a second lead from the second conductive dielectric layer on the front side of the substrate.
[0088] The lead-out process directly affects the reliability of the connection. In a specific embodiment of the present invention, the first lead can be led out from the first conductive dielectric layer on the back side of the substrate through a conductive medium such as platinum paste or silver paste, and the second lead can also be led out from the second conductive dielectric layer on the front side of the substrate through a conductive medium such as platinum paste or silver paste. This is a low-temperature connection method, which involves printing or dotting a conductive paste (usually a polymer paste containing metal particles), then embedding or pressing the lead into the uncured paste, and finally curing it at a low temperature (usually 200-400°C) to form a connection. The advantage is the low process temperature and minimal thermal impact on the film and substrate.
[0089] During implementation, a precision dispensing device can be used to apply silver paste to the center of the electrode, forming a paste dot with a diameter of approximately 0.1-0.3 mm. Then, a platinum or gold wire with a diameter of 0.05-0.1 mm is vertically inserted into the paste dot. After the paste cures, a strong connection is formed. Alternatively, a laser welding machine with precisely controlled power and focal length can be used to form a tiny solder joint at the center of the electrode. After the paste connection, a low-temperature curing process is required, such as maintaining it in an oven at 150-250°C for 30-60 minutes.
[0090] An alternative approach is to lead the first lead from the first conductive dielectric layer on the back side of the substrate using ultrasonic or laser welding, and the second lead from the second conductive dielectric layer on the front side of the substrate using the same method. Welding can form a metallurgical bond, and the connection strength and conductivity are generally superior to slurry bonding, but it requires higher process control to prevent thermal damage. Ultrasonic welding uses high-frequency vibration friction to generate heat for connection, making it suitable for connecting thin metal wires to planar electrodes; laser welding, on the other hand, has concentrated energy and a small heat-affected zone, but requires fine optimization of welding parameters.
[0091] Preferably, the first lead extends from the center of the first conductive dielectric layer on the back side of the substrate, and the second lead extends from the center of the second conductive dielectric layer on the front side of the substrate. This maximizes the contact area between the lead and the electrode, and the two leads form a radially parallel structure. Besides facilitating installation, this method maximizes the contact area between the electrode and the lead, improving the reliability of the lead electrical connection and the lead tensile strength. When implementing this preferred embodiment, precise dispensing or welding operations are required at the center of the electrode area. In actual production lines, a vision positioning system can be used to automatically identify the electrode center position and guide the dispensing head or welding needle for precise operation.
[0092] S5 encapsulates the thin-film resistance temperature sensor chip in a fully sealed package.
[0093] In this embodiment of the invention, step S5 involves fully encapsulating the thin-film resistance temperature sensor chip. Specifically, the thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, second conductive dielectric layer, first lead, and second lead, is radially placed inside the encapsulation shell and sintered under inert gas protection to form a fully encapsulated package.
[0094] As mentioned earlier, this embodiment preferably uses a glass shell. A suitable temperature is selected to cause the glass to shrink, thus forming a fully sealed glass enclosure. "Radially positioned" refers to the sensor chip's axis being perpendicular to or at a certain angle to the glass shell's axis, allowing the leads on both sides to easily extend from both ends of the shell. The sintering process requires precise control of the temperature profile (usually near the glass softening point) to ensure the glass shell shrinks uniformly under surface tension, tightly encapsulating and sealing the sensor chip without damaging internal components. An inert gas protective atmosphere prevents oxidation of metal components at high temperatures.
[0095] A typical sintering process profile is as follows: Heat to near the glass softening point (e.g., 600-800°C, depending on the glass type) at a rate of 5-10°C / min, hold for 10-30 minutes to allow the glass to fully flow and encapsulate the chip, then slowly cool to room temperature at a controlled rate (e.g., 3-5°C / min) to eliminate internal stress. The entire process is carried out in a flowing inert gas atmosphere. After sintering, the glass shell should form a seamless fusion interface with the chip and leads.
[0096] This invention can be widely applied in fields such as industrial process control, automotive electronics, home appliances, medical equipment, and aerospace where high-precision and high-stability temperature measurement is required.
[0097] The thin-film resistance temperature sensor and its preparation method disclosed in the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the core idea of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. A thin-film resistance temperature sensor, characterized in that, include: Base, A thin-film resistor, wherein the thin-film resistor is disposed on the front side of a substrate, and includes a resistive region, a first electrode region, and a second electrode region; An insulating protective layer that covers the resistive region of the thin-film resistor; A first conductive dielectric layer is connected to the first electrode region of the thin film resistor and guides the electrical signal of the first electrode region of the thin film resistor to the back side of the substrate. The first lead extends from the first conductive dielectric layer on the back side of the substrate; The second lead extends from the second electrode region of the thin-film resistor on the front side of the substrate.
2. A thin-film resistance temperature sensor, characterized in that, include: Base, A thin-film resistor, wherein the thin-film resistor is disposed on the front side of a substrate, and includes a resistive region, a first electrode region, and a second electrode region; An insulating protective layer that covers the resistive region of the thin-film resistor; A first conductive dielectric layer is connected to the first electrode region of the thin film resistor and guides the electrical signal of the first electrode region of the thin film resistor to the back side of the substrate. The second conductive dielectric layer is located on the front side of the substrate, covering the second electrode region of the thin film resistor and a portion of the insulating protective layer, but not covering the first electrode region of the thin film resistor. The first lead extends from the first conductive dielectric layer on the back side of the substrate; The second lead extends from the second conductive dielectric layer on the front side of the substrate.
3. The thin-film resistance temperature sensor according to claim 2, characterized in that, It also includes a packaging shell for encapsulating the thin-film resistance temperature sensor chip formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, second conductive dielectric layer, first lead and second lead.
4. The thin-film resistance temperature sensor according to claim 3, characterized in that, The encapsulation shell is a glass shell.
5. The thin-film resistance temperature sensor according to claim 2, characterized in that, The first lead extends from the middle of the first conductive dielectric layer on the back side of the substrate, and the second lead extends from the middle of the second conductive dielectric layer on the front side of the substrate.
6. A method for fabricating a thin-film resistance temperature sensor, characterized in that, Includes the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography. S2 covers the resistive region of the thin-film resistor with an insulating protective layer; S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate. S4 A first lead is drawn from the first conductive dielectric layer on the back side of the substrate, and a second lead is drawn from the second electrode region on the front side of the substrate; S5 The thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, first lead and second lead together, is radially placed inside the package shell and sintered under inert gas protection to form a fully sealed package.
7. A method for fabricating a thin-film resistance temperature sensor, characterized in that, Includes the following steps: S1 forms a thin film resistive layer on the substrate by physical vapor deposition and / or chemical vapor deposition, and cuts out the thin film resistive pattern using photolithography. S2 covers the resistive region of the thin-film resistor with an insulating protective layer; S3 forms a first conductive dielectric layer on the back side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing, and connects the first electrode region of the thin film resistor on the front side of the substrate to the first conductive dielectric layer on the back side of the substrate. A second conductive dielectric layer is formed on the front side of the substrate by physical vapor deposition and / or chemical vapor deposition and / or thick film printing. The second conductive dielectric layer covers the second electrode region of the thin film resistor and a portion of the insulating protective layer, but does not cover the first electrode region of the thin film resistor. S4 extends a first lead from the first conductive dielectric layer on the back side of the substrate and extends a second lead from the second conductive dielectric layer on the front side of the substrate.
8. The method for fabricating a thin-film resistance temperature sensor according to claim 7, characterized in that, The preparation method further includes: S5 The thin-film resistance temperature sensor chip, which is formed by the substrate, thin-film resistor, insulating protective layer, first conductive dielectric layer, second conductive dielectric layer, first lead and second lead together, is radially placed inside the package shell and sintered under inert gas protection to form a fully sealed package.
9. The method for fabricating a thin-film resistance temperature sensor according to claim 7, characterized in that, In step S3, the first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate, specifically as follows: The first electrode region of the thin-film resistor on the front side of the substrate is connected to the first conductive dielectric layer on the back side of the substrate by sputtering or coating a conductive dielectric at the side end; or... A via is formed on the substrate and a conductive medium is filled in the via to connect the first electrode region of the thin film resistor on the front side of the substrate to the first conductive medium layer on the back side of the substrate.
10. The method for fabricating a thin-film resistance temperature sensor according to claim 7, characterized in that, In step S4, the first lead is led out from the middle of the first conductive dielectric layer on the back side of the substrate through platinum paste or silver paste, and the second lead is led out from the middle of the second conductive dielectric layer on the front side of the substrate through platinum paste or silver paste. Alternatively, the first lead is led out from the middle of the first conductive dielectric layer on the back side of the substrate by soldering, and the second lead is led out from the middle of the second conductive dielectric layer on the front side of the substrate by soldering.