Corrosion-resistant, high-thermal-conductivity ceramic base NTC thermistor

Abstract

This invention discloses a corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor, comprising an NTC thermistor chip, a glass package, Dummes wires, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer. The bottom of the ceramic chip is fused to the top of the ceramic base. The ceramic base has two through holes. The NTC thermistor chip is located within the glass package. One end of the Dummes wire is electrically welded to the electrodes on both sides of the NTC thermistor chip, and the other end extends through the through hole in the ceramic base. The graphene high thermal conductivity bonding layer is coated on the lower end face of the ceramic base. The outer surface of the ceramic base and the inner wall of the through holes are coated with a composite corrosion-resistant coating. Its advantages are that it solves the problems of glass package detachment and poor wire contact caused by the penetration of corrosive media; the Dummes wire adopts a composite corrosion-resistant coating design to prevent the wire from oxidizing and rusting in corrosive environments; and heat is quickly transferred to the NTC thermistor chip, meeting the rapid temperature measurement requirements in high heat flux scenarios.

Description

Technical Field

[0001] This invention belongs to the field of NTC thermistor technology, specifically relating to a corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor. Background Technology

[0002] Power electronic devices in emerging technology fields such as new energy batteries and robots generate a large amount of heat during operation, resulting in high heat flux density. This places extremely high demands on the temperature response speed and thermal conductivity of the matching NTC thermistors. Existing NTC thermistors have ceramic bases with low thermal conductivity, resulting in slow heat transfer and lag in temperature response. This makes it impossible to detect the core temperature of the device in real time and can easily lead to untimely temperature control and safety hazards. At the same time, the poor thermal conductivity of the ceramic base and the heat dissipation substrate causes heat to accumulate at the contact interface, further reducing the temperature measurement response efficiency and making it difficult to meet the rapid temperature measurement requirements of high heat flux density scenarios.

[0003] Meanwhile, with the rapid development of high technology, new energy equipment and unmanned equipment are widely used in corrosive environments such as chemical and marine environments. These environments are subject to corrosive factors such as acid and alkali media, salt spray, and corrosive gases. The ceramic base of existing NTC thermistors is a bare ceramic structure with no corrosion-resistant protection on the surface, making it susceptible to corrosion by corrosive media. This leads to a loose and cracked ceramic base structure, gaps at the junction of the Dumme wire leads and the double holes, which in turn causes air leakage and failure of temperature measurement accuracy. At the same time, the interface between the glass package and the ceramic base is easily penetrated by corrosive media, causing the package to fall off. This significantly shortens the service life of the thermistor and fails to meet the long-term use requirements of corrosive environments. Summary of the Invention

[0004] To address the above problems, the main objective of this invention is to design a corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor includes an NTC thermistor chip, a glass package, Dumme wires, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer. The bottom of the glass package is fused to the top of the ceramic base. The ceramic base has two parallel through holes that penetrate the upper and lower surfaces of the ceramic base. Several heat dissipation bumps are evenly distributed on the outer surface. The NTC thermistor chip is fused into the glass package. There are two Dumme wires, one end of which is electrically welded to the electrodes on both sides of the NTC thermistor chip, and the other end extends through the through holes in the ceramic base. The graphene high thermal conductivity bonding layer is coated on the lower surface of the ceramic base. The outer surface of the ceramic base and the inner wall of the through holes are coated with a composite corrosion-resistant coating. The ceramic base contains 5wt% to 7wt% BN; The high thermal conductivity graphene bonding layer consists of graphene microsheets in a 1:2 ratio and high-temperature resistant ceramic adhesive. The Dumex lead is made of an iron-nickel-copper alloy core, a copper cladding, and a borate thermal conductive coating wrapped from the inside out. The borate thermal conductive coating contains 5wt% to 8wt% Al2O3. The composite corrosion-resistant coating consists of SiO2 and Al2O3 in a 7:3 ratio.

[0006] As a further description of the present invention, the composite corrosion-resistant coating extends to the joint surface between the glass package and the ceramic base, and extends 5-8 mm onto the glass package.

[0007] As a further description of the present invention, the composite corrosion-resistant coating has a thickness of 0.03 to 0.08 mm, is applied by the sol-gel method, and is sintered and cured at 500 to 600°C.

[0008] As a further description of the present invention, the inner wall of the through hole is subjected to thermally conductive polishing treatment, and the roughness Ra≤0.2μm.

[0009] As a further description of the present invention, the thickness of the high thermal conductivity bonding layer is 0.05 to 0.1 mm, and the wall thickness of the glass encapsulation body is 0.1 to 0.2 mm.

[0010] As a further description of the present invention, the surface of the NTC thermistor chip is subjected to a thermally enhanced coating treatment.

[0011] As a further description of the present invention, the graphene high thermal conductivity bonding layer is coated onto the lower end surface of the ceramic base by a scraping method, cured at room temperature, and then dried at 120°C.

[0012] As a further description of the present invention, the height of the heat dissipation bump is 0.1 to 0.2 mm and the diameter is 0.2 to 0.3 mm.

[0013] Compared with the prior art, the technical advantages of the present invention are as follows: This invention provides a corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor. By coating the ceramic base with a SiO2-Al2O3 composite corrosion-resistant coating, it effectively resists the erosion of acidic and alkaline media, salt spray, and corrosive gases. Furthermore, the composite corrosion-resistant coating extends to the bonding surface, forming a fully encapsulated corrosion-resistant protection, effectively preventing the penetration of corrosive media and solving the problems of glass encapsulation detachment and poor lead contact caused by the penetration of corrosive media. The DuMesh leads adopt a composite corrosion-resistant plating design to prevent the leads from oxidizing and rusting in corrosive environments. The ceramic base uses a high thermal conductivity BN phase combined with the thermally conductive Al2O3 component in the ceramic base to improve the thermal conductivity of the ceramic. At the same time, heat dissipation bumps are set on the surface of the ceramic base to achieve rapid heat conduction and significantly shorten the temperature response time. A graphene high thermal conductivity bonding layer is added to the lower end face of the ceramic base, which effectively solves the interface thermal resistance problem between the ceramic base and the heat dissipation substrate. Heat is quickly transferred to the NTC thermistor chip, meeting the rapid temperature measurement requirements of high heat flow scenarios. By applying a thermally enhanced coating to the NTC thermistor chip and combining it with a thin-walled glass package, the obstruction in the heat transfer path is reduced, thereby improving the temperature measurement accuracy. Adding thermally conductive powder to the borate thermally conductive coating of the DuMesh leads enables efficient heat transfer between the leads and the ceramic base, preventing localized heat accumulation. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the internal structure of the Dumex lead wire.

[0016] In the figure, 1. NTC thermistor chip, 2. Dummex wire, 21. Iron-nickel-copper alloy core, 22. Copper cladding, 23. Borate thermal conductive coating, 23. Borate thermal conductive coating, 3. Glass package, 4. Ceramic base, 41. Heat dissipation bump, 5. Sleeve. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings: A corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor mainly consists of an NTC thermistor chip 1, a glass package 3, Dumme wire leads 2, a ceramic base 4, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer. The bottom of the glass package 3 is fused to the top of the ceramic base. The outer surface of the ceramic base 4 has several uniformly distributed heat dissipation bumps 41 and two parallel through holes penetrating the upper and lower surfaces of the ceramic base. The inner walls of the through holes are thermally polished to a roughness Ra≤0.2μm. The ceramic base 4 has an outer diameter of 1.45mm, a height of 1.2mm, a through hole diameter of 0.45mm, a hole spacing of 0.18mm, and heat dissipation bumps with a height of 0.1~0.2mm and a diameter of 0.2~0.3mm. Figure 1 As shown.

[0018] The NTC thermistor chip 1 is fused and fixed within a glass package 3, and its surface is treated with a thermally enhanced coating. Two Dummex leads 2 are attached, one end electrically soldered to the electrodes on both sides of the NTC thermistor chip 1, and the other end extending through a through-hole in the ceramic base 4. A graphene high thermal conductivity bonding layer is applied to the lower surface of the ceramic base 4 using a scraping method, cured at room temperature, and then dried at 120°C. The thickness of the high thermal conductivity bonding layer is 0.05–0.1 mm, and the wall thickness of the glass package is 0.1–0.2 mm.

[0019] The outer surface of the ceramic base 4 and the inner wall of the through hole are coated with a composite corrosion-resistant coating. The composite corrosion-resistant coating extends to the joint surface between the glass package and the ceramic base, and extends 5-8 mm onto the glass package. The composite corrosion-resistant coating consists of SiO2 and Al2O3 in a 7:3 ratio. The thickness of the composite corrosion-resistant coating is 0.03-0.08 mm. It is applied by the sol-gel method and cured by sintering at 500-600℃.

[0020] The ceramic base contains 5wt% to 7wt% BN; The high thermal conductivity graphene bonding layer consists of graphene microsheets in a 1:2 ratio and high-temperature resistant ceramic adhesive. The Dumex lead 2 is made of an iron-nickel-copper alloy core 21, a copper cladding layer 22, and a borate thermally conductive coating 23, which are wrapped sequentially from the inside out. The borate thermally conductive coating contains 5wt% to 8wt% Al2O3. Figure 2 As shown. Example 1

[0021] The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor of this application is mainly composed of an NTC thermistor chip, a glass package, Dumex wire leads, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer, and is prepared through the following steps: Step 1: Add 5wt% BN to the ceramic base slurry, then sinter to make a ceramic base with through holes and heat dissipation bumps, and polish the inner wall of the through hole until the surface roughness Ra of the inner wall of the through hole is ≤0.2μm; Step 2: Add 5 wt% Al2O to the borate thermally conductive coating 3， The iron-nickel-copper alloy core, copper cladding, and borate thermally conductive coating are wrapped together from the inside out to form a Dumex wire lead. Step 3: Perform thermal conductivity enhancement coating treatment on the surface of the NTC thermistor chip. After the treatment is completed, electrically weld one end of the two Dummel wires to the electrodes on both sides of the NTC thermistor chip. Step 4: Place the soldered NTC thermistor into the hollow glass package, and pass the connected Dumex wire through the through hole on the ceramic base to fuse the bottom of the glass package to the top of the ceramic base into one piece. Step 5: Prepare a graphene high thermal conductivity bonding layer by mixing graphene micro flakes with high-temperature resistant ceramic adhesive in a 1:2 ratio. Apply the layer to the lower surface of the ceramic base using a scraping method, cure at room temperature, and then dry at 120°C.

[0022] Step 6: Prepare a corrosion-resistant coating by mixing SiO2 and Al2O3 in a 7:3 ratio. Apply the coating to the outer surface of the ceramic base and the inner wall of the through hole using the sol-gel method, extending 5 mm onto the glass encapsulation. Then, sinter and cure at 500℃ to complete the preparation of the corrosion-resistant, high thermal conductivity ceramic base NTC thermistor.

[0023] In this embodiment, the thickness of the high thermal conductivity bonding layer is 0.05mm, the wall thickness of the glass encapsulation is 0.1mm, the thickness of the composite corrosion-resistant coating is 0.03mm, the outer diameter of the ceramic base is 1.45mm, the height is 1.2mm, the diameter of the through hole is 0.45mm, the hole spacing between the two through holes is 0.18mm, and the height of the heat dissipation bump is 0.1mm and the diameter is 0.2mm. Example 2

[0024] The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor of this application is mainly composed of an NTC thermistor chip, a glass package, Dumex wire leads, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer, and is prepared through the following steps: Step 1: Add 7wt% BN to the ceramic base slurry, then sinter to make a ceramic base with through holes and heat dissipation bumps, and polish the inner wall of the through hole until the surface roughness Ra of the inner wall of the through hole is ≤0.2μm; Step 2: Add 6 wt% Al2O to the borate thermally conductive coating 3， The iron-nickel-copper alloy core, copper cladding, and borate thermally conductive coating are wrapped together from the inside out to form a Dumex wire lead. Step 3: Perform thermal conductivity enhancement coating treatment on the surface of the NTC thermistor chip. After the treatment is completed, electrically weld one end of the two Dummel wires to the electrodes on both sides of the NTC thermistor chip. Step 4: Place the soldered NTC thermistor into the hollow glass package, and pass the connected Dumex wire through the through hole on the ceramic base to fuse the bottom of the glass package to the top of the ceramic base into one piece. Step 5: Prepare a graphene high thermal conductivity bonding layer by mixing graphene micro flakes with high-temperature resistant ceramic adhesive in a 1:2 ratio. Apply the layer to the lower surface of the ceramic base using a scraping method, cure at room temperature, and then dry at 120°C.

[0025] Step 6: Prepare a corrosion-resistant coating by mixing SiO2 and Al2O3 in a 7:3 ratio. Apply the coating to the outer surface of the ceramic base and the inner wall of the through hole using the sol-gel method, extending 7 mm onto the glass encapsulation. Then, sinter and cure at 550℃ to complete the preparation of the corrosion-resistant, high thermal conductivity ceramic base NTC thermistor.

[0026] In this embodiment, the thickness of the high thermal conductivity bonding layer is 0.07 mm, the wall thickness of the glass encapsulation body is 0.15 mm, the thickness of the composite corrosion-resistant coating is 0.05 mm, the outer diameter of the ceramic base is 1.45 mm, the height is 1.2 mm, the diameter of the through hole is 0.45 mm, the hole spacing between the two through holes is 0.18 mm, and the height of the heat dissipation bump is 0.15 mm and the diameter is 0.25 mm. Example 3

[0027] The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor of this application is mainly composed of an NTC thermistor chip, a glass package, Dumex wire leads, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer, and is prepared through the following steps: Step 1: Add 8wt% BN to the ceramic base slurry, then sinter to make a ceramic base with through holes and heat dissipation bumps, and polish the inner wall of the through hole until the surface roughness Ra of the inner wall of the through hole is ≤0.2μm; Step 2: Add 8 wt% Al2O to the borate thermally conductive coating 3， The iron-nickel-copper alloy core, copper cladding, and borate thermally conductive coating are wrapped together from the inside out to form a Dumex wire lead. Step 3: Perform thermal conductivity enhancement coating treatment on the surface of the NTC thermistor chip. After the treatment is completed, electrically weld one end of the two Dummel wires to the electrodes on both sides of the NTC thermistor chip. Step 4: Place the soldered NTC thermistor into the hollow glass package, and pass the connected Dumex wire through the through hole on the ceramic base to fuse the bottom of the glass package to the top of the ceramic base into one piece. Step 5: Prepare a graphene high thermal conductivity bonding layer by mixing graphene micro flakes with high-temperature resistant ceramic adhesive in a 1:2 ratio. Apply the layer to the lower surface of the ceramic base using a scraping method, cure at room temperature, and then dry at 120°C.

[0028] Step 6: Prepare a corrosion-resistant coating by mixing SiO2 and Al2O3 in a 7:3 ratio. Apply the coating to the outer surface of the ceramic base and the inner wall of the through hole using the sol-gel method, extending 8 mm onto the glass encapsulation. Then, sinter and cure at 600℃ to complete the preparation of the corrosion-resistant, high thermal conductivity ceramic base NTC thermistor.

[0029] In this embodiment, the thickness of the high thermal conductivity bonding layer is 0.1 mm, the wall thickness of the glass encapsulation body is 0.2 mm, the thickness of the composite corrosion resistant coating is 0.08 mm, the outer diameter of the ceramic base is 1.45 mm, the height is 1.2 mm, the diameter of the through hole is 0.45 mm, the hole spacing between the two through holes is 0.18 mm, and the height of the heat dissipation bump is 0.2 mm and the diameter is 0.3 mm.

[0030] The performance test results of Examples 1-3 are as follows: Thermal response time Sealing performance Soaking in pH2 and pH12 solutions for 1000 hours 3.5% NaCl salt spray test for 1000 hours Temperature cycle of -55℃ to 350℃ 100 times Example 1 42ms <![CDATA[10 -10 Pa·m3 / s]]> No corrosion, no coating peeling, and no oxidation of the leads. The structure is neither loose nor leaky. No cracks in the coating Example 2 40ms <![CDATA[10 -10 Pa·m3 / s]]> No corrosion, no coating peeling, and no oxidation of the leads. The structure is neither loose nor leaky. No cracks in the coating Example 3 43ms <![CDATA[10 -10 Pa·m3 / s]]> No corrosion, no coating peeling, and no oxidation of the leads. The structure is neither loose nor leaky. No cracks in the coating The test results above show that by coating the ceramic base with a SiO2-Al2O3 composite corrosion-resistant coating that extends to the joint surface, a fully enclosed corrosion-resistant protection is formed, which effectively resists the erosion of acid and alkali media, salt spray, and corrosive gases. Dumeis leads feature a composite corrosion-resistant coating design to prevent oxidation and rust in corrosive environments; The ceramic base incorporates a high thermal conductivity BN phase in combination with the thermally conductive Al2O3 component in the ceramic base, thereby improving the thermal conductivity of the ceramic, enabling rapid heat conduction, and significantly shortening the temperature response time. A graphene high thermal conductivity bonding layer is added to the lower end face of the ceramic base, which effectively solves the interface thermal resistance problem between the ceramic base and the heat dissipation substrate. Heat is quickly transferred to the NTC thermistor chip, meeting the rapid temperature measurement requirements of high heat flow scenarios. Adding thermally conductive powder to the borate thermally conductive coating of the DuMesh leads enables efficient heat transfer between the leads and the ceramic base, preventing localized heat accumulation.

[0031] In summary, the corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor of this application is suitable for power electronic devices in emerging technology fields such as new energy batteries and robots, which generate a large amount of heat and operate in environments with high heat flux density. It can also meet the usage requirements of corrosive environments such as chemical plants and marine environments.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the direction and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A corrosion-resistant, high thermal conductivity ceramic-based NTC thermistor, characterized in that: The device includes an NTC thermistor chip, a glass package, Dumme wires, a ceramic base, a composite corrosion-resistant coating, and a graphene high thermal conductivity bonding layer. The bottom of the glass package is fused to the top of the ceramic base. The ceramic base has two parallel through holes that penetrate the upper and lower surfaces of the ceramic base, and its outer surface is uniformly covered with several heat dissipation bumps. The NTC thermistor chip is fused into the glass package. There are two Dumme wires, one end of which is electrically welded to the electrodes on both sides of the NTC thermistor chip, and the other end extends through the through holes in the ceramic base. The graphene high thermal conductivity bonding layer is coated on the lower surface of the ceramic base. The outer surface of the ceramic base and the inner wall of the through holes are coated with a composite corrosion-resistant coating. The ceramic base contains 5wt% to 7wt% BN; The graphene high thermal conductivity bonding layer is composed of graphene microsheets and high-temperature resistant ceramic adhesive in a 1:2 ratio. The Dumex wire is made of an iron-nickel-copper alloy core, a copper cladding, and a borate thermal conductive coating wrapped from the inside out. The borate thermal conductive coating contains 5wt% to 8wt% Al2O3. The composite corrosion-resistant coating consists of SiO2 and Al2O3 in a 7:3 ratio.

2. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The composite corrosion-resistant coating extends to the interface between the glass package and the ceramic base, and extends 5-8 mm onto the glass package.

3. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The composite corrosion-resistant coating has a thickness of 0.03 to 0.08 mm, is applied using the sol-gel method, and is sintered and cured at 500 to 600°C.

4. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The inner wall of the through hole is subjected to thermally conductive polishing treatment, with a roughness Ra≤0.2μm.

5. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The thickness of the high thermal conductivity bonding layer is 0.05–0.1 mm, and the wall thickness of the glass encapsulation body is 0.1–0.2 mm.

6. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The surface of the NTC thermistor chip is treated with a thermally enhanced coating.

7. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The graphene high thermal conductivity bonding layer is coated onto the lower surface of the ceramic base using a scraping method, cured at room temperature, and then dried at 120°C.

8. The corrosion-resistant, high thermal conductivity ceramic-base NTC thermistor according to claim 1, characterized in that: The height of the heat dissipation bump is 0.1-0.2 mm, and the diameter is 0.2-0.3 mm.

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