Electrode structure of thermistor and thermistor

Abstract

The thermistor comprises a ceramic body, and the electrode structure comprises a bottom surface electrode which is located on the bottom surface of the ceramic body and serves as an outer electrode; the single inner electrode is located in the ceramic body, has a projection overlapping area with the bottom surface electrode in the vertical direction, and is used for forming a current path; wherein no direct connection point exists between the bottom surface electrode and the single inner electrode, electric connection is achieved through the projection overlapping area, and the resistance value of the thermistor is regulated and controlled by regulating and controlling the area of the overlapping area and the distance between the bottom surface electrode and the inner electrode. According to the electrode structure design of the thermistor, the production process is simplified, the cost of the end paste and the inner paste is greatly reduced, the reliability of the product is remarkably improved, and the requirements of the industries such as electronic products and automobiles for high reliability and low cost of the thermistor are met.

Description

Technical Field

[0001] The present invention relates to a thermistor, and particularly to an electrode structure of a thermistor and a thermistor. Background Art

[0002] In recent years, with the continuous improvement of the requirements for the reliability and cost of thermistor products in industries such as electronic products and automobiles, it is urgent to improve the reliability of products and reduce costs. The traditional thermistor with an internal electrode structure adopts a dipping process, and the internal electrode is designed with a multi-layer electrode structure. Figure 1 Shows the traditional three-layer internal electrode thermistor electrode design, including a ceramic body 1, an outer electrode 2, an internal electrode 3, and a connection point 4 between the end electrode and the internal electrode. Its resistance value is composed of the parallel connection of the internal circuit resistance and the body resistance, that is, R 总 =(R 内 ×R 体 ) / (R 内 ×R 体 ), where R 内 =ρ*L / S (ρ is the resistivity, determined by the material and process, L is the distance between overlapping layers, and S is the overlapping area). Figure 2 Shows a schematic diagram of the internal equivalent circuit of a traditional three-layer internal electrode thermistor. In the electrode structure design of the traditional thermistor, there is a risk of failure at the connection between the multi-layer electrode structure internal electrode and the end electrode. In addition, the costs of the end paste and the internal paste are at a relatively high level, and can basically reach 40%-80% of the total cost.

[0003] It should be noted that the information disclosed in the above background art section is only used for understanding the background of the present application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] The main purpose of the present invention is to overcome the defects existing in the above background art, and provide an electrode structure of a thermistor and a thermistor.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] An electrode structure of a thermistor, the thermistor includes a ceramic body, and the electrode structure includes:

[0007] A bottom electrode, located at the bottom surface of the ceramic body, serving as an outer electrode;

[0008] A single internal electrode, located inside the ceramic body, having a projection overlapping area with the bottom electrode in the vertical direction, for forming a current path;

[0009] Among them, there is no direct connection point between the bottom electrode and the single inner electrode, and the electrical connection is achieved through the projection overlapping area. The resistance value of the thermistor is regulated by controlling the area of the overlapping area and the distance between the bottom electrode and the inner electrode.

[0010] Furthermore, the length L1 of the inner electrode satisfies 1 / 3L ≤ L1 ≤ 2 / 3L, and the width W1 of the inner electrode satisfies 1 / 3W ≤ W1 ≤ 2 / 3W;

[0011] The length L2 of the bottom electrode satisfies 1 / 6L1 ≤ L2 ≤ 1 / 3L1, and the width W2 of the bottom electrode satisfies 2 / 3W ≤ W2 ≤ W;

[0012] The distance W3 between the bottom electrode and the inner electrode satisfies 1 / 5W ≤ W3 ≤ 4 / 5W;

[0013] Among them, L is the length of the ceramic body, and W is the width of the ceramic body;

[0014] The projected overlapping area S between the bottom electrode and the inner electrode satisfies the formula S = (L2 - (L - L1) / 2) × W1, and the internal circuit resistance R_inner is regulated by the overlapping area S and the distance W3.

[0015] Furthermore, the single inner electrode is formed inside the ceramic body by the tape casting process, and the electrode paste forms a preset pattern through screen printing.

[0016] A thermistor, comprising:

[0017] A ceramic body;

[0018] A bottom electrode, located at the bottom of the ceramic body, serving as an external electrode;

[0019] A single inner electrode, located inside the ceramic body, having a projected overlapping area with the bottom electrode in the vertical direction, for forming a current path;

[0020] Among them, there is no direct connection point between the bottom electrode and the single inner electrode, and the electrical connection is achieved through the projection overlapping area. The resistance value of the thermistor is regulated by controlling the area of the overlapping area and the distance between the bottom electrode and the inner electrode.

[0021] Furthermore, the length L1 of the inner electrode satisfies 1 / 3L ≤ L1 ≤ 2 / 3L, and the width W1 of the inner electrode satisfies 1 / 3W ≤ W1 ≤ 2 / 3W;

[0022] The length L2 of the bottom electrode satisfies 1 / 6L1 ≤ L2 ≤ 1 / 3L1, and the width W2 of the bottom electrode satisfies 2 / 3W ≤ W2 ≤ W;

[0023] The distance W3 between the bottom electrode and the inner electrode satisfies 1 / 5W ≤ W3 ≤ 4 / 5W;

[0024] where L is the length of the ceramic body and W is the width of the ceramic body;

[0025] The projected overlapping area S between the bottom electrode and the inner electrode satisfies the formula S = (L2 - (L - L1) / 2) × W1, and the internal circuit resistance R_inner is regulated by the overlapping area S and the distance W3.

[0026] Further, the ceramic body is made of a thermosensitive paste, and the thermosensitive paste forms a green tape on a PET film through a casting process, and is made into a ceramic body through cutting, laminating, and sintering.

[0027] Further, the single inner electrode is formed inside the ceramic body through a casting process, and the electrode paste forms a preset pattern through screen printing.

[0028] Further, the thermistor is an integrated structure formed by laminating an electrode-containing green tape and a common green tape, followed by pressing, cutting, and sintering.

[0029] The present invention has the following beneficial effects:

[0030] The present invention provides an electrode structure of a thermistor and a thermistor. Through an innovative electrode structure design, the direct connection between the end electrode and the inner electrode in the traditional multi-layer electrode structure is eliminated, thereby completely eliminating the risk of connection point failure and significantly improving the reliability of the product. The outer electrode (end electrode) adopts a bottom electrode design, and the inner electrode adopts a single electrode design. This structural optimization not only simplifies the production process but also greatly reduces the usage cost of the end paste and the inner paste, resulting in a significant decrease in the product cost, which can reach 40%-80% of the traditional design. In addition, by precisely regulating the projected overlapping area between the bottom electrode and the inner electrode and the distance between them, the resistance value of the thermistor can be flexibly adjusted to ensure that the electrical characteristics of the product are further optimized while achieving the same performance. This design meets the high-reliability and low-cost requirements of the thermistor in industries such as electronic products and automobiles, and also provides a new solution for the structural optimization and performance improvement of the thermistor.

[0031] Other beneficial effects in the embodiments of the present invention will be further described below. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the electrode design of a traditional three-layer inner electrode thermistor.

[0033] Figure 2 It is a schematic diagram of the internal equivalent circuit of a traditional three-layer inner electrode thermistor.

[0034] Figure 3 Schematic diagram of the electrode structure design of the thermistor according to an embodiment of the present invention.

[0035] Figure 4 Schematic diagram of the internal equivalent circuit of the thermistor according to an embodiment of the present invention.

[0036] Figure 5 Process flow chart of the electrode structure design of the thermistor according to an embodiment of the present invention.

[0037] Figure 6 Design and cost comparison chart between Embodiment 1 and Comparative Example 1 of the present invention.

[0038] Figure 7 Design and cost comparison chart between Embodiment 2 and Comparative Example 2 of the present invention Detailed implementation manners

[0039] The following makes a detailed description of the implementation manners of the present invention. It should be emphasized that the following description is merely exemplary and not intended to limit the scope of the present invention and its applications.

[0040] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for a fixing function or for a coupling or communicating function.

[0041] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0042] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0043] Refer to Figure 3, embodiments of the present invention provide an electrode structure for a thermistor. The thermistor includes a ceramic body 1. The electrode structure includes: a bottom electrode located on the bottom surface of the ceramic body 1 and serving as an outer electrode 2; a single inner electrode 3 located inside the ceramic body 1 and having a projection overlapping area with the bottom electrode in the vertical direction for forming a current path. Among them, there is no direct connection point between the bottom electrode and the single inner electrode 3, and electrical connection is achieved through the projection overlapping area to eliminate the risk of connection point failure, and the resistance value of the thermistor is regulated by regulating the area of the overlapping area and the distance between the bottom electrode and the inner electrode 3.

[0044] In some embodiments, the length L1 of the inner electrode 3 satisfies 1 / 3L ≤ L1 ≤ 2 / 3L, and the width W1 of the inner electrode 3 satisfies 1 / 3W ≤ W1 ≤ 2 / 3W; the length L2 of the bottom electrode satisfies 1 / 6L1 ≤ L2 ≤ 1 / 3L1, and the width W2 of the bottom electrode satisfies 2 / 3W ≤ W2 ≤ W; the distance W3 between the bottom electrode and the inner electrode 3 satisfies 1 / 5W ≤ W3 ≤ 4 / 5W. Among them, L is the length of the ceramic body 1, and W is the width of the ceramic body 1. The projection overlapping area S between the bottom electrode and the inner electrode 3 satisfies the formula S = (L2 - (L - L1) / 2) × W1, and the internal circuit resistance R_inner is regulated by the overlapping area S and the distance W3.

[0045] In some embodiments, as an example size, the length L1 of the inner electrode 3 is 600 μm to 900 μm, the width W1 of the inner electrode 3 is 200 μm to 240 μm, and the length L2 of the bottom electrode is 200 μm to 350 μm.

[0046] In some embodiments, the inner electrode 3 is formed inside the ceramic body 1 by a casting process, and the electrode paste forms a preset pattern through screen printing.

[0047] Refer to Figure 3 , embodiments of the present invention also provide a thermistor, including: a ceramic body 1; a bottom electrode located on the bottom surface of the ceramic body 1 and serving as an outer electrode 2; a single inner electrode 3 located inside the ceramic body 1 and having a projection overlapping area with the bottom electrode in the vertical direction for forming a current path. Among them, there is no direct connection point between the bottom electrode and the single inner electrode 3, and electrical connection is achieved through the projection overlapping area to eliminate the risk of connection point failure, and the resistance value of the thermistor is regulated by regulating the area of the overlapping area and the distance between the bottom electrode and the inner electrode 3.

[0048] In some embodiments, the length L1 of the inner electrode 3 satisfies 1 / 3L ≤ L1 ≤ 2 / 3L, and the width W1 of the inner electrode 3 satisfies 1 / 3W ≤ W1 ≤ 2 / 3W; the length L2 of the bottom electrode satisfies 1 / 6L1 ≤ L2 ≤ 1 / 3L1, and the width W2 of the bottom electrode satisfies 2 / 3W ≤ W2 ≤ W; the distance W3 between the bottom electrode and the inner electrode 3 satisfies 1 / 5W ≤ W3 ≤ 4 / 5W; where L is the length of the ceramic body 1 and W is the width of the ceramic body 1; the projected overlapping area S between the bottom electrode and the inner electrode 3 satisfies the formula S = (L2 - (L - L1) / 2) × W1, and the internal circuit resistance R_inner is regulated by the overlapping area S and the distance W3.

[0049] In some embodiments, as an example of dimensions, the length L1 of the inner electrode 3 is from 600 μm to 900 μm, the width W1 of the inner electrode 3 is from 200 μm to 240 μm, and the length L2 of the bottom electrode is from 200 μm to 350 μm.

[0050] In some embodiments, the ceramic body is made of a thermosensitive paste, and the thermosensitive paste forms a green tape on a PET film through a casting process, and is made into a ceramic body through cutting, laminating, and sintering.

[0051] In some embodiments, the single inner electrode is formed inside the ceramic body through a casting process, and the electrode paste forms a preset pattern through screen printing.

[0052] In some embodiments, the thermistor is an integrated structure formed by laminating an electrode-containing green tape and a common green tape followed by pressing, cutting, and sintering.

[0053] Through the innovative design of the thermistor electrode structure, the present invention eliminates the direct connection between the end electrode and the inner electrode in the traditional multi-layer electrode structure, thereby completely eliminating the risk of connection point failure and significantly improving the reliability of the product. The outer electrode (end electrode) adopts a bottom electrode design, and the inner electrode adopts a single electrode design. This structural optimization not only simplifies the production process but also greatly reduces the usage cost of the end paste and the inner paste, resulting in a significant decrease in the product cost, which can reach 40% - 80% of the traditional design. In addition, by precisely regulating the projected overlapping area between the bottom electrode and the inner electrode and the distance between them, the resistance value of the thermistor can be flexibly adjusted to ensure that the electrical characteristics of the product are further optimized on the premise of achieving the same performance. This design provides a new solution for the structural optimization and performance improvement of thermistors while meeting the high-reliability and low-cost requirements of the electronics, automotive and other industries for thermistors.

[0054] The following further describes specific embodiments of the present invention.

[0055] Figure 3The electrode structure design of the thermistor according to the embodiment of the present invention is shown, including a ceramic body 1, an outer electrode 2, and an inner electrode 3. L is the length of the porcelain body, and W is the width of the porcelain body; L1 is the length of the inner electrode (1 / 3L ≤ L1 ≤ 2 / 3L), and W1 is the width of the inner electrode (1 / 3W ≤ W1 ≤ 2 / 3W); L2 is the length of the bottom electrode (1 / 6L1 ≤ L2 ≤ 1 / 3L1), and W2 is the width of the bottom electrode (2 / 3W ≤ W2 ≤ W); W3 is the distance between the bottom electrode and the inner electrode (1 / 5W ≤ W3 ≤ 4 / 5W). There is a projection overlapping area S between the bottom electrode and the inner electrode, and the overlapping area is S = (L2 - (L - L1) / 2) * W1. The overlapping area S and W3 are used to regulate R inside, and then regulate the resistance value of the entire product. Figure 4 The internal equivalent circuit of the thermistor according to the embodiment of the present invention is shown.

[0056] Thermistor Preparation

[0057] The thermistor product is prepared by using the processes of batching, casting, cutting, printing, laminating, warm isostatic pressing, cutting, chamfering, sintering, electroplating, sorting, and taping.

[0058] The manufacturing process of the thermistor specifically includes the following steps:

[0059] Step 1: Cast the thermistor paste on the PET film to form a green tape roll, and cut it to form a single green tape sheet.

[0060] Step 2: Form an electrode pattern on the green tape by screen printing the paste.

[0061] Step 3: Stack the ordinary green tape and the green tape with electrodes through designs such as the number of layers and displacement to form a BAR block.

[0062] Step 4: Following Step 3, produce the finished product through processes of pressing, cutting, chamfering, sintering, end electrodes, electroplating, sorting, and taping.

[0063] The following Examples 1 - 2 of the present invention and Comparative Examples 1 - 2 with traditional designs are all prepared according to the above manufacturing processes.

[0064] See Figure 6 , for Example 1 of the present invention, its configuration is specifically as follows: the length of the inner electrode L1 = 900 μm; the width of the inner electrode W1 = 240 μm; the length of the bottom electrode L2 = 350 μm. The end electrode is designed as a bottom single-sided electrode; the number of connection points between the end electrode and the inner electrode is 0.

[0065] Comparative Example 1 has a three-layer electrode structure, and its configuration is specifically as follows: the length of the inner electrode L1 = 700 μm; the width of the inner electrode W1 = 200 μm; the end electrode is designed as a five-sided electrode (located around and on the top); the number of connection points between the end electrode and the inner electrode = 4.

[0066] The experimental results show that, compared with Comparative Example 1 with a three-layer electrode structure, in the case of achieving the same performance, the cost of the inner electrode in Example 1 of the present invention is reduced by 48.6%, the cost of the end electrode is reduced by 85%, and the number of connection points between the end electrode and the inner electrode is reduced to 0, eliminating the risk of connection point failure.

[0067] See Figure 7 , for Example 2 of the present invention, its configuration is specifically: the length L1 of the inner electrode = 600 μm; the width W1 of the inner electrode = 200 μm; the length L2 of the bottom electrode = 200 μm. The end electrode is designed as a bottom single-sided electrode; the number of connection points between the end electrode and the inner electrode is 0.

[0068] Comparative Example 2 is a five-layer electrode structure, and its configuration is specifically: the length L1 of the inner electrode = 500 μm; the width W1 of the inner electrode = 100 μm; the end electrode is designed as a five-sided electrode (located around and on the top); the number of connection points between the end electrode and the inner electrode = 6

[0069] The experimental results show that, compared with Comparative Example 2 with a five-layer electrode structure, in the case of achieving the same performance, the cost of the inner electrode in Example 2 of the present invention is reduced by 52%, the cost of the end electrode is reduced by 78%, and the number of connection points between the end electrode and the inner electrode is reduced to 0, eliminating the risk of connection point failure.

[0070] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several alternatives or modifications can be made to these described embodiments, and these alternative or modified forms should all be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. Without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope of protection of the patent application.

Claims

1. An electrode structure of a thermistor, the thermistor comprising a ceramic body, characterized in that: The electrode structure comprises: A bottom electrode, located on the bottom surface of the ceramic body, serving as an external electrode; A single inner electrode is located inside the ceramic body and has a projection overlap area with the bottom electrode in a vertical direction, so as to form a current path; There is no direct connection point between the bottom electrode and the single inner electrode, and electrical connection is achieved through the projected overlapping area. The resistance of the thermistor is controlled by adjusting the area of ​​the overlapping area and the distance between the bottom electrode and the inner electrode.

2. The electrode structure of thermistor according to claim 1, characterized in that: The inner electrode length L1 satisfies 1 / 3L≤L1≤2 / 3L, and the inner electrode width W1 satisfies 1 / 3W≤W1≤2 / 3W; The bottom electrode length L2 satisfies 1 / 6L1≤L2≤1 / 3L1, and the bottom electrode width W2 satisfies 2 / 3W≤W2≤W; The distance W3 between the bottom electrode and the inner electrode satisfies 1 / 5W≤W3≤4 / 5W; Wherein, L is the length of the ceramic body, and W is the width of the ceramic body; The projected overlapping area S of the bottom electrode and the inner electrode satisfies the formula S=(L2-(L-L1) / 2)×W1, and the internal circuit resistance R is regulated by the overlapping area S and the distance W3.

3. The electrode structure of thermistor according to any one of claims 1 to 2, characterized in that: The single inner electrode is formed inside the ceramic body by a tape casting process, and the electrode slurry is formed into a preset pattern by screen printing.

4. A thermistor, characterized in that: include: Ceramic body; A bottom electrode, located on the bottom surface of the ceramic body, serving as an external electrode; A single inner electrode is located inside the ceramic body and has a projection overlap area with the bottom electrode in a vertical direction, so as to form a current path; There is no direct connection point between the bottom electrode and the single inner electrode, and electrical connection is achieved through the projected overlapping area. The resistance of the thermistor is controlled by adjusting the area of ​​the overlapping area and the distance between the bottom electrode and the inner electrode.

5. The thermistor according to claim 4, characterized in that: The inner electrode length L1 satisfies 1 / 3L≤L1≤2 / 3L, and the inner electrode width W1 satisfies 1 / 3W≤W1≤2 / 3W; The bottom electrode length L2 satisfies 1 / 6L1≤L2≤1 / 3L1, and the bottom electrode width W2 satisfies 2 / 3W≤W2≤W; The distance W3 between the bottom electrode and the inner electrode satisfies 1 / 5W≤W3≤4 / 5W; Wherein, L is the length of the ceramic body, and W is the width of the ceramic body; The projected overlapping area S of the bottom electrode and the inner electrode satisfies the formula S=(L2-(L-L1) / 2)×W1, and the internal circuit resistance R is regulated by the overlapping area S and the distance W3.

6. The thermistor according to any one of claims 4 to 5, characterized in that: The ceramic body is made of heat-sensitive slurry, which is formed into a green tape on a PET film through a casting process, and is cut, laminated and sintered to form a ceramic body.

7. The thermistor according to any one of claims 4 to 5, characterized in that: The single inner electrode is formed inside the ceramic body by a tape casting process, and the electrode slurry is formed into a preset pattern by screen printing.

8. The thermistor according to any one of claims 4 to 5, characterized in that: The thermistor is an integrated structure formed by laminating an electrode-containing green tape and a common green tape, and then pressing, cutting and sintering.

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