High-reliability thermistor chip

Abstract

The utility model provides a kind of high-reliability thermistor chip, the thermistor chip includes NTC ceramic body and the multilayer electrode distributed on the opposite two surfaces of the NTC ceramic body, wherein each multilayer electrode at least includes heat shock resistance layer and welding layer in order from inside to outside respectively, heat shock resistance layer directly contacts NTC ceramic body, buffer conduction to the heat shock of ceramic body and make heat quickly disperse, and welding layer is used for the welding of chip and device.The thermistor chip with the structure of the utility model has stronger heat shock resistance, good stability, high reliability, and can be used in relatively extreme high-temperature environment.

Description

Technical Field

[0001] This utility model relates to the field of NTC thermistor technology, specifically a high-reliability thermistor chip. Background Technology

[0002] With its precise temperature measurement and fast real-time response, NTC thermistor bare chips have become the core unit for temperature monitoring in thermopile and power devices such as IGBTs and silicon carbide (SiC). Their performance directly affects the operational safety and long-term reliability of the devices. With the development of technology, extreme application scenarios have placed higher demands on the performance of bare chips, which is particularly evident in the field of silicon carbide (SiC) power devices.

[0003] As a new generation of power devices, silicon carbide is experiencing a surge in demand in high-end applications such as electric vehicles and energy storage systems due to its significant advantages in high temperature resistance, high frequency, and high efficiency. However, its operating environment is extremely harsh: 1. High-temperature operation: The device needs to withstand high-temperature environments of 150~170℃ or even higher for a long time during operation; 2. High-temperature welding: To match its high-temperature application characteristics, a 350℃ high-lead reflow soldering process is required during the installation phase. This process (high-lead solder can provide higher reliability and quality redundancy, and is suitable for complex environments) has the characteristics of long welding time and extreme high-temperature and high-lead environment.

[0004] Under such harsh conditions, ordinary bare NTC thermistor chips are not up to the task—high-temperature soldering can easily cause resistance drift and instability failure, and long-term high-temperature operation will accelerate performance degradation, making it difficult to meet the core requirements of silicon carbide devices for reliability and long lifespan throughout the entire life cycle.

[0005] Therefore, for extreme scenarios such as silicon carbide, developing high-performance NTC thermistor bare chips that can withstand high-lead and high-temperature soldering processes and operate stably in long-term high-temperature environments has become the key to solving the pain point of device safety monitoring, which is also the core background of the research and development of this patented technology. Utility Model Content

[0006] The purpose of this invention is to provide a thermistor chip with a novel structure to solve the problem of poor durability of existing thermistor chips under extreme high-temperature environments.

[0007] To achieve the above objectives, this utility model provides the following technical solution: A high-reliability thermistor chip includes an NTC ceramic body and multiple layers of electrodes distributed on two opposite surfaces of the NTC ceramic body. Each multilayer electrode includes at least a thermal shock resistant layer and a solder layer in order from the inside out. The thermal shock resistant layer is in direct contact with the NTC ceramic body, buffering the thermal shock conducted to the ceramic body and dissipating the heat quickly. The solder layer is used for soldering the chip to the device.

[0008] Preferably, the heat-shock resistant layer is a Ru layer or a Ru-containing alloy layer.

[0009] Preferably, the welding layer is a silver layer or a silver-palladium alloy layer.

[0010] Furthermore, the thickness of the welding layer is 3-15 micrometers, and the thickness of the heat-shock resistant layer is 10-100 nanometers.

[0011] Preferably, the multilayer electrode further includes a stabilizing layer between the heat shock resistant layer and the welding layer.

[0012] More preferably, the stabilizing layer is a Cr layer, a Cu layer, a TiN layer, or a Cr / Ni composite layer.

[0013] Furthermore, the thickness of the stabilizing layer is 20~2000 nanometers.

[0014] Preferably, a protective layer is provided on the four surfaces of the thermistor chip, excluding the two electrode surfaces.

[0015] More preferably, the protective layer is a glaze layer.

[0016] Furthermore, the thickness of the glaze layer is 10~100 micrometers.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: Compared with existing technologies, the chip structure of this invention adopts a multi-layer electrode structure composed of a heat-shock-resistant layer, a stabilizing layer, and a welding layer. The heat-shock-resistant layer is responsible for good adhesion and contact between the electrode and the ceramic body, has good heat resistance, and can quickly disperse heat to avoid thermal stress damaging the ceramic body. The material of the heat-shock-resistant layer also has sufficient strength and stability to prevent metal diffusion into the ceramic body and causing ceramic body failure. The stabilizing layer, as the transition between the heat-shock-resistant layer and the welding layer and the skeleton of the multi-layer electrode, can improve the stability of the electrode. The welding layer itself has good solderability and electrical conductivity. Furthermore, this invention also provides a protective layer on the four exposed surfaces other than the electrode surface. The protective layer can prevent heat and environmental stress from impacting the ceramic body from the sides, effectively prevent moisture and corrosive gases from damaging the ceramic body, prevent metal migration, pinhole corrosion, etc., and also protect the electrode layer, preventing the electrode layer from falling off the ceramic body, etc. More preferably, a glaze layer is formed after glaze coating and curing, which provides tight protection for the four exposed sides of the ceramic body. The thermistor chip using the structure of this utility model has stronger thermal shock resistance, good stability, and high reliability, and can be used in relatively extreme high-temperature environments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of one embodiment of the high-reliability thermistor chip of this utility model; Figure 2 This is a schematic diagram of another embodiment of the high-reliability thermistor chip of this utility model; Figure 3 This is a schematic diagram of a high-reliability thermistor chip with a side protective layer.

[0019] In the diagram: 1. NTC ceramic body; 2. Multilayer electrode; 3. Protective layer; 21. Welding layer; 22. Thermal shock resistant layer; 23. Stabilizing layer. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] See Figure 1 The diagram illustrates the structure of the high-reliability thermistor chip of this invention. The thermistor chip of this invention includes an NTC ceramic body 1 and multiple layers of electrodes 2 distributed on two opposing surfaces of the NTC ceramic body 1. Each multiple layer of electrodes sequentially includes at least an outermost solder layer 21 and an innermost heat-shock resistant layer 22 that is in direct contact with the ceramic body 1.

[0024] The function of the heat-shock resistant layer is to form a tight contact with the NTC ceramic body, ideally enabling the electrode to be composite with the ceramic body, maintaining the adhesion between the electrode and the ceramic body. Furthermore, the heat-shock resistant layer needs to have good electrical conductivity and ensure resistance to external thermal shock and environmental stress, preventing thermal and environmental stress from being transferred to the core NTC ceramic body and causing ceramic body failure. On the other hand, the material of the heat-shock resistant layer should have sufficient strength and stability to prevent metal diffusion into the ceramic body, which could lead to ceramic body failure. Metallic Ru (Ru) has excellent thermal conductivity and superior heat resistance, and exhibits extremely high tolerance and stability to various physical and chemical effects, preventing metal diffusion. Therefore, as a preferred choice, the heat-shock resistant layer is a Ru layer or a Ru-containing alloy layer.

[0025] The solder layer is located on the outermost layer of the electrode and its function is to bond the chip to the device, such as through reflow soldering and bonding soldering. Therefore, the solder layer needs to have sufficient solderability and conductivity, as well as a certain level of strength and thermal conductivity. For performance and cost considerations, a silver layer is the preferred choice for the solder layer, but a silver-palladium alloy layer is also acceptable.

[0026] While an electrode structure with a heat-shock resistant layer and a solder layer can guarantee chip performance under extreme environments to a certain extent, such as solderability and stability at high temperatures, it is even more preferable to include a stabilizing layer 22 between the solder layer and the heat-shock resistant layer as a multi-layer electrode framework. Figure 2 As shown.

[0027] The stabilizing layer serves as the framework of the multilayer electrode, possessing high supporting strength and stable properties. It also acts as a transition between the welding layer and the thermal shock resistant layer, exhibiting good composite performance and a certain degree of thermal buffering capacity. Therefore, Cr, Cu, Cr / Ni composite, or TiN layers are preferred choices for the stabilizing layer.

[0028] The stabilizing layer can be a single layer, such as using a single element or an alloying element as the stabilizing layer. Alternatively, the stabilizing layer can be a composite layer, for example, using materials with different properties to achieve better performance. Therefore, as described above, the multilayer electrode structure of the chip can be two-layer, three-layer, four-layer, or even more five-layer, six-layer, etc.

[0029] The thickness of the welding layer is 3~15 micrometers, the thickness of the stabilizing layer is 20~2000 nanometers, and the thickness of the thermal shock resistant layer is 10~100 nanometers, so as to provide sufficient protection for the ceramic body without affecting its temperature measurement performance.

[0030] Although the two electrode surfaces of the NTC ceramic body are protected by multiple layers of electrodes, enabling it to withstand adverse conditions in extreme operating environments, high temperatures, thermal stress, environmental stress, as well as air, moisture, and corrosive gases can still impact the ceramic body on the four surfaces of the thermistor chip other than the two electrode surfaces. Therefore, see [link to relevant documentation]. Figure 3 A protective layer 3 is also provided on the four sides of the thermistor chip.

[0031] The protective layer can be made of various protective materials, such as silicone resin, epoxy resin, and silicone resin. However, for applications in extreme high-temperature environments, it is preferable to use the encapsulation materials commonly used in NTC thermistor packaging. For example, during manufacturing, a slurry formed by glass sealing powder or glaze is applied to the four sides of the NTC thermistor chip, and after drying and sintering, a glaze layer is formed. The thickness of the glaze layer is 10~100 micrometers.

[0032] Any aspects of this utility model not described in detail are well-known technologies to those skilled in the art.

[0033] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications and equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A high-reliability thermistor chip, characterized in that, The thermistor chip includes an NTC ceramic body and multiple layers of electrodes distributed on two opposite surfaces of the NTC ceramic body. Each multiple layer of electrodes includes at least a heat shock resistant layer and a solder layer in order from the inside out. The heat shock resistant layer is in direct contact with the NTC ceramic body, buffering the thermal shock conducted to the ceramic body and dissipating the heat quickly. The solder layer is used for soldering the chip to the device. The heat shock resistant layer is a Ru layer or a Ru-containing alloy layer.

2. The high-reliability thermistor chip as described in claim 1, characterized in that, The welding layer is a silver layer or a silver-palladium alloy layer.

3. The high-reliability thermistor chip as described in claim 1 or 2, characterized in that, The thickness of the weld layer is 3-15 micrometers, and the thickness of the heat shock resistant layer is 10-100 nanometers.

4. The high-reliability thermistor chip as described in claim 1, characterized in that, The multilayer electrode also includes a stabilizing layer between the heat shock resistant layer and the welding layer.

5. The high-reliability thermistor chip as described in claim 4, characterized in that, The stabilizing layer is a Cr layer, a Cu layer, a TiN layer, or a Cr / Ni composite layer.

6. The high-reliability thermistor chip as described in claim 4 or 5, characterized in that, The thickness of the stabilizing layer is 20~2000 nanometers.

7. The high-reliability thermistor chip as described in claim 1, characterized in that, A protective layer is also provided on the four surfaces of the thermistor chip, excluding the two electrode surfaces.

8. The high-reliability thermistor chip as described in claim 7, characterized in that, The protective layer is a glaze layer.

9. The high-reliability thermistor chip as described in claim 8, characterized in that, The thickness of the glaze layer is 10~100 micrometers.

Images