Ceramic thermosensitive element

Abstract

A ceramic thermosensitive element comprises a ceramic body, an inner electrode layer, an interconnection structure and a packaging layer. The inner electrode layer is provided with a first inner electrode layer and a second inner electrode layer which respectively cover the upper surface and the lower surface of the ceramic body. The interconnection structure is provided with a first interconnection structure and a second interconnection structure which are respectively connected with the first inner electrode layer and the second inner electrode layer and extend to the lower part of the second inner electrode layer. The packaging layer wraps the ceramic body, the inner electrode layer and the interconnection structures, so that part of the first interconnection structures and part of the second interconnection structures are located on the lower side of the packaging layer.

Description

Technical Field

[0001] This invention relates to a ceramic thermistor, and more particularly, to a low-resistance, encapsulated ceramic thermistor. Background Technology

[0002] The resistance of a conventional positive temperature coefficient (PTC) element is highly sensitive to temperature changes. Under normal operating conditions, a PTC element maintains a very low resistance, allowing the circuit to function properly. However, when overcurrent or overheating occurs, causing the temperature to rise to a critical temperature, also known as the Curie point, its resistance will instantly jump to a high resistance state (e.g., 10 ohms). 4 When the current exceeds Ω (above a certain value), it triggers the circuit, cutting off excessive current to protect the battery or circuit components. Therefore, PTC devices are now integrated into various circuit components to prevent damage from overcurrent.

[0003] Positive temperature coefficient (PTC) elements can be broadly classified into two categories: polymer PTC elements and ceramic PTC elements. Commonly known PPTC elements have poor resistance hysteresis characteristics after tripping and are not resistant to high voltages. While CPTC elements generally have high voltage resistance and their resistance can recover to a value close to their original value, their high normal resistance results in poor conductivity, thus limiting their application range.

[0004] Regarding the aforementioned CPTC components, please refer to... Figure 1a and Figure 1b The figures show a perspective view and a cross-sectional view along line AA of a conventional ceramic thermistor 100. The core component of the ceramic thermistor 100 is a ceramic body 1 with a positive temperature coefficient. To ensure a good electrical connection between the ceramic body 1 and an external power source, low-resistance ohmic contact electrodes must first be printed at both ends of it, such as... Figure 1a and Figure 1bThe first inner electrode layer 2a and the second inner electrode layer 2b are shown. Next, an outer electrode layer (not shown) can be formed on the surfaces of the first inner electrode layer 2a and the second inner electrode layer 2b by electroplating, forming a finished product with a specific length L1, width W1, and thickness T1. However, in conventional ceramic thermistors 100, the first inner electrode layer 2a and the second inner electrode layer 2b are located on two end faces, which makes the distance G1 between the two electrodes too large, resulting in excessively high resistance when the element is not activated (i.e., not triggered). If the distance between the two end faces of the ceramic body 1 is simply shortened to reduce resistance, changes in other electrical characteristics are easily amplified by miniaturization, leading to less stable performance.

[0005] In view of this, there is an urgent need to develop a new ceramic thermistor that has low resistance and stable performance in other electrical characteristics. Summary of the Invention

[0006] According to one embodiment of the present invention, a ceramic thermistor includes a ceramic body, an internal electrode layer, an interconnect structure, and an encapsulation layer. The ceramic body has an upper surface and a lower surface opposite to the upper surface. The internal electrode layer has a first internal electrode layer and a second internal electrode layer respectively covering the upper and lower surfaces of the ceramic body. The interconnect structure has a first interconnect structure and a second interconnect structure respectively connecting the first and second internal electrode layers and extending below the second internal electrode layer. The encapsulation layer covers the ceramic body, the internal electrode layer, and the interconnect structure, such that a portion of the first interconnect structure and a portion of the second interconnect structure are located below the second internal electrode layer within the encapsulation layer.

[0007] According to some embodiments, the first inner electrode layer and the second inner electrode layer are separated by a distance. The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area, respectively, when viewed from above and from below. The ratio obtained by dividing this distance by the first surface area or the second surface area is less than 3.

[0008] According to some embodiments, this spacing is between 0.15 mm and 0.19 mm, while the first or second surface area is between 0.08 mm². 2 With 0.13mm 2 between.

[0009] According to some embodiments, the ceramic thermistor further includes lead-out electrodes. The lead-out electrodes have a first lead-out electrode and a second lead-out electrode respectively connected to a first interconnect structure and a second interconnect structure, and extend downwards in a direction away from the interconnect structures.

[0010] According to some embodiments, the encapsulation layer covers the lead electrodes, thereby exposing only a portion of the first lead electrode and a portion of the second lead electrode on the same side.

[0011] According to some embodiments, the ceramic thermistor further includes an external electrode layer. The external electrode layer has a first external electrode layer and a second external electrode layer covering an exposed first lead electrode and an exposed second lead electrode, respectively.

[0012] According to some embodiments, the ceramic body comprises a first component and a second component. The first component comprises barium, strontium, calcium, and a first trace element. The second component comprises titanium, manganese, and a second trace element. The first and second trace elements are selected from the group consisting of ytterbium, lanthanum, cerium, antimony, praseodymium, neodymium, samarium, europium, gadolinium, tantalum, erbium, thulium, and combinations thereof. The volume resistivity of the ceramic body is less than 15 Ω·cm.

[0013] According to some embodiments, with the total mole number of barium, strontium, calcium and the first trace element being 100%, and strontium accounting for 20% to 25%; calcium accounting for 4.5% to 5%; and the first trace element accounting for 0.13% to 0.17%, the Curie temperature of the ceramic body is 80°C to 130°C.

[0014] According to some embodiments, the total mole count of titanium, manganese and the second trace element is 100%, with manganese accounting for 0.01% to 0.03% and the second trace element accounting for 0.02% to 0.04%.

[0015] According to some embodiments, the ceramic body has a first resistance value at 25°C; the ceramic body has a second resistance value at 125°C; and the ratio of the second resistance value to the first resistance value is 10 or more.

[0016] According to one embodiment of the present invention, a ceramic thermistor includes a ceramic body assembly, an internal electrode layer, an interconnect structure, and an encapsulation layer. The ceramic body assembly has a first ceramic body and a second ceramic body stacked below the first ceramic body. The internal electrode layer has a first internal electrode layer, a second internal electrode layer, a third internal electrode layer, and a fourth internal electrode layer, wherein the first and second internal electrode layers respectively cover opposite upper and lower surfaces of the first ceramic body, and the third and fourth internal electrode layers respectively cover opposite upper and lower surfaces of the second ceramic body, such that the second internal electrode layer faces the third internal electrode layer. The interconnect structure has a first interconnect structure, a second interconnect structure, and a third interconnect structure, wherein the first interconnect structure connects the second and third internal electrode layers, the second interconnect structure connects the fourth internal electrode layer, and the third interconnect structure connects the first internal electrode layer, and the first, second, and third interconnect structures further extend below the fourth internal electrode layer. The encapsulation layer covers the ceramic body assembly, the internal electrode layer, and the interconnect structure, such that a portion of the first, second, and third interconnect structures are located below the fourth internal electrode layer within the encapsulation layer.

[0017] According to some embodiments, the first inner electrode layer and the second inner electrode layer are separated by a distance. The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area, respectively, when viewed from above and from below. The ratio obtained by dividing this distance by the first surface area or the second surface area is less than 3.

[0018] According to some embodiments, the ceramic thermistor further includes lead-out electrodes. The lead-out electrodes have a first lead-out electrode and a second lead-out electrode. The first lead-out electrode is connected to a first interconnect structure, while the second lead-out electrode is connected to a second interconnect structure and a third interconnect structure, and extends downward in a direction away from the interconnect structures.

[0019] According to some embodiments, the encapsulation layer covers the lead electrodes, thereby exposing only a portion of the first lead electrode and a portion of the second lead electrode on the same side.

[0020] According to some embodiments, the ceramic thermistor further includes an external electrode layer. The external electrode layer has a first external electrode layer and a second external electrode layer covering an exposed first lead electrode and an exposed second lead electrode, respectively.

[0021] According to one embodiment of the present invention, a ceramic thermistor includes a ceramic body assembly, an internal electrode layer, an interconnect structure, and an encapsulation layer. The ceramic body assembly has a first ceramic body and a second ceramic body stacked below the first ceramic body. The internal electrode layer has a first internal electrode layer, a second internal electrode layer, a third internal electrode layer, and a fourth internal electrode layer, wherein the first and second internal electrode layers respectively cover opposite upper and lower surfaces of the first ceramic body, and the third and fourth internal electrode layers respectively cover opposite upper and lower surfaces of the second ceramic body, with the second internal electrode layer directly contacting the third internal electrode layer. The interconnect structure has a first interconnect structure and a second interconnect structure respectively connecting the first and fourth internal electrode layers and extending below the fourth internal electrode layer. The encapsulation layer covers the ceramic body assembly, the internal electrode layer, and the interconnect structure, such that a portion of the first interconnect structure and a portion of the second interconnect structure are located below the fourth internal electrode layer within the encapsulation layer.

[0022] According to some embodiments, the first inner electrode layer and the second inner electrode layer are separated by a distance. The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area, respectively, when viewed from above and from below. The ratio obtained by dividing this distance by the first surface area or the second surface area is less than 3.

[0023] According to some embodiments, the ceramic thermistor further includes lead-out electrodes. The lead-out electrodes have a first lead-out electrode and a second lead-out electrode respectively connected to a first interconnect structure and a second interconnect structure, and extend downwards in a direction away from the interconnect structures.

[0024] According to some embodiments, the encapsulation layer covers the lead electrodes, thereby exposing only a portion of the first lead electrode and a portion of the second lead electrode on the same side.

[0025] According to some embodiments, the ceramic thermistor further includes an external electrode layer. The external electrode layer has a first external electrode layer and a second external electrode layer covering an exposed first lead electrode and an exposed second lead electrode, respectively. Attached Figure Description

[0026] Figure 1a and Figure 1b The perspective view and cross-sectional view of a conventional ceramic thermistor are shown respectively;

[0027] Figure 2 A cross-sectional view showing a ceramic thermistor element of a first embodiment of the present invention;

[0028] Figures 3a to 3d This invention demonstrates the fabrication process of a ceramic thermistor element according to a first embodiment of the present invention.

[0029] Figure 4 A cross-sectional view showing a ceramic thermistor element according to a second embodiment of the present invention;

[0030] Figure 5 A cross-sectional view showing a ceramic thermistor element of a third embodiment of the present invention; and

[0031] Figure 6 This displays the temperature curve during the sintering process.

[0032] The reference numerals in the attached figures are explained as follows:

[0033] 1, 10: Ceramic body

[0034] 10a: First ceramic body

[0035] 10b: Second ceramic body

[0036] 2a, 20a: First inner electrode layer

[0037] 2b, 20b: Second inner electrode layer

[0038] 20c: Third inner electrode layer

[0039] 20d: Fourth inner electrode layer

[0040] 30a: First interconnect structure

[0041] 30b: Second interconnect structure

[0042] 30c: Third interconnect structure

[0043] 40a: First lead-out electrode

[0044] 40b: Second lead-out electrode

[0045] 50a: First outer electrode layer

[0046] 50b: Second outer electrode layer

[0047] 60: Encapsulation layer

[0048] 60a: First encapsulation layer

[0049] 60b: Second encapsulation layer

[0050] 100, 200, 300, 400: Ceramic thermistors

[0051] G1, G2: Spacing

[0052] H1: First perforation

[0053] H2: Second perforation

[0054] L1, L2: Length

[0055] T1, T2: Thickness

[0056] W1: Width Detailed Implementation

[0057] To make the above and other technical contents, features and advantages of the present invention more apparent and understandable, relevant embodiments are provided below, and detailed descriptions are given in conjunction with the accompanying drawings.

[0058] Please refer to Figure 2 This is a cross-sectional view of a ceramic thermistor 200 according to a first embodiment of the present invention. The ceramic thermistor 200 includes a ceramic body 10, inner electrode layers (i.e., a first inner electrode layer 20a and a second inner electrode layer 20b), interconnect structures (i.e., a first interconnect structure 30a and a second interconnect structure 30b), lead electrodes (i.e., a first lead electrode 40a and a second lead electrode 40b), an encapsulation layer 60, and outer electrode layers (i.e., a first outer electrode layer 50a and a second outer electrode layer 50b). The inner electrode layers of the ceramic thermistor 200 have a short electrode spacing and are electrically connected to the external lead electrodes and outer electrode layers. Furthermore, the structure of the encapsulation layer 60 allows for miniaturization of its internal wiring (such as interconnect structures) and increases the conductive area of ​​good electrical conductors. Further details are provided below.

[0059] The ceramic body 10 is a hexahedron with a positive temperature coefficient. To enable it to conduct electricity with an external power source, an internal electrode layer with good ohmic contact must first be formed on it. For example... Figure 2As shown, the inner electrode layer comprises a first inner electrode layer 20a and a second inner electrode layer 20b, respectively covering the upper and lower surfaces of the ceramic body 10. The material of the inner electrode layer can be selected from the group consisting of titanium (Ti), nickel (Ni), chromium (Cr), nickel-chromium alloy (Ni-Cr alloy), nickel-copper alloy (Ni-Cu alloy), silver (Ag), copper (Cu), aluminum (Al), tin (Sn), and combinations thereof, and can be formed by printing, coating, vapor deposition, or other conventional film-forming methods. For example, a nickel-chromium alloy can be formed into a paste and printed onto the upper surface of the ceramic body 10, and then sintered to form the first inner electrode layer 20a. It should also be noted that, to shorten the current conduction distance, the first inner electrode layer 20a and the second inner electrode layer 20b of the present invention are not disposed on the two end faces of the ceramic body 10. That is, the end face formed by the short side of the ceramic body 10 will not be covered with the inner electrode layer. Furthermore, on one side, the inner electrode layer covers at least 80% of the surface of the ceramic body 10 in both top and bottom views (i.e., the xz plane). For example, taking the area of ​​the upper surface of the ceramic body 10 as 100%, the area covered by the first inner electrode layer 20a is more than 80%, and the area covered by the second inner electrode layer 20b is also more than 80%. It is worth mentioning that the present invention further adjusts the ratio of electrode spacing to electrode area, making this structural design applicable to packaged products of different sizes. More specifically, the first inner electrode layer 20a and the second inner electrode layer 20b are separated by a distance G2. The first inner electrode layer 20a and the second inner electrode layer 20b have a first surface area and a second surface area, respectively, in top and bottom views. The ratio obtained by dividing the spacing G2 by the first surface area or the second surface area is less than 3, preferably between 1.4 and 2. For example, the spacing G2 can be set between 0.15 mm and 0.19 mm, while the first or second surface area is between 0.08 mm². 2 ) and 0.13mm 2 Between these two ranges, an appropriate value is selected to adjust the aforementioned ratio to be less than 3.

[0060] The interconnect structure has a first interconnect structure 30a and a second interconnect structure 30b, which are respectively connected to the first inner electrode layer 20a and the second inner electrode layer 20b, and extend below the second inner electrode layer 20b. Specific details are as follows: The first interconnect structure 30a is flat against the first inner electrode layer 20a along the z-axis, and extends beyond the upper surface of the ceramic body 10, then continues to extend downward along the y-axis, sequentially extending beyond the first inner electrode layer 20a, the ceramic body 10, and the second inner electrode layer 20b. The aforementioned z-axis is approximately parallel to the first inner electrode layer 20a, and the y-axis is approximately perpendicular to the first inner electrode layer 20a. The second interconnect structure 30b extends downward from the second inner electrode layer 20b along the y-axis and has a gradually widening cross-sectional profile, facilitating subsequent connection with the lead-out electrodes. The position above the first inner electrode layer 20a is defined as the upper side, and the position below the second inner electrode layer 20b is defined as the lower side. Thus, the two ends extending from the inner electrode layer of the first interconnect structure 30a and the second interconnect structure 30b are substantially flush and both are designed to be located on the same side, i.e., the lower side. That is, the contacts of the first interconnect structure 30a and the second interconnect structure 30b are both located on the same side. Furthermore, the contact area between the interconnect structure and the inner electrode layer can also be adjusted. Taking the top view area of ​​the first inner electrode layer 20a as 100%, the contact area between the first interconnect structure 30a and the first inner electrode layer 20a is at least 5%. Similarly, taking the bottom view area of ​​the second inner electrode layer 20b as 100%, the contact area between the second interconnect structure 30b and the second inner electrode layer 20b is at least 5%. In one embodiment, the material of the interconnect structure can be selected from the group consisting of copper (Cu), silver (Ag), aluminum (Al), tin (Sn), nickel (Ni), and combinations thereof.

[0061] The lead-out electrodes have a first lead-out electrode 40a and a second lead-out electrode 40b, which are respectively connected to the first interconnect structure 30a and the second interconnect structure 30b, and extend downwards away from the interconnect structure. Specific details are as follows: The first lead-out electrode 40a and the second lead-out electrode 40b can be extremely thin metal sheets, serving as pads for connection to external circuitry. The first lead-out electrode 40a extends downwards along the y-axis from the lower end of the first interconnect structure 30a, while the second lead-out electrode 40b extends downwards along the z-axis parallel to the second inner electrode layer 20b from the lower end of the second interconnect structure 30b, and then extends downwards along the y-axis. To improve fault tolerance, both the first lead-out electrode 40a and the second lead-out electrode 40b are designed to be relatively wide. That is, in the first lead-out electrode 40a, the end face connecting to the first interconnect structure 30a has a longer length along the z-axis; and in the second lead-out electrode 40b, the end face connecting to the second interconnect structure 30b has a longer length along the z-axis. Generally, both the first lead electrode 40a and the second lead electrode 40b have roughly rectangular cross-sections. Furthermore, to avoid the risk of short circuits due to the two electrodes being too close together, one of the electrodes can be designed as an inverted L-shape. For example... Figure 2As shown, the first lead-out electrode 40a has a rectangular cross-section, while the second lead-out electrode 40b has an inverted L-shaped cross-section. In other words, the second lead-out electrode 40b can be considered as consisting of an upper half and a lower half with rectangular cross-sections. The upper half is designed to be wider to improve fault tolerance, while the lower half is further shifted to the right and not aligned with the upper second interconnect structure 30b, thereby avoiding the risk of short circuits. In some embodiments, both the first lead-out electrode 40a and the second lead-out electrode 40b are inverted L-shaped and arranged in opposite directions to each other, thus increasing the distance between them. Furthermore, for manufacturing convenience, the aforementioned inverted L-shaped second lead-out electrode 40b can be composed of a metal plating layer and a metal sheet. For example, the upper half of the second lead-out electrode 40b can be a rectangular metal plating layer, and the lower half can be a rectangular metal sheet; and the metal sheet of the second lead-out electrode 40b is the same as that of the first lead-out electrode 40a. In one embodiment, the shortest distance between the first lead-out electrode 40a and the second lead-out electrode 40b is at least 0.1 mm. In one embodiment, the material of the lead-out electrodes may be selected from the group consisting of copper (Cu), silver (Ag), aluminum (Al), tin (Sn), nickel (Ni), and combinations thereof.

[0062] The encapsulation layer 60 covers the ceramic body 10, the inner electrode layer, the interconnect structure, and the lead-out electrodes, thereby exposing only a portion of the first lead-out electrode 40a and a portion of the second lead-out electrode 40b on the same side. Specific details are as follows. The encapsulation layer 60 has a hexahedral structure. Figure 2 In the figure, the encapsulation layer 60 has an upper surface, a lower surface, a left side, and a right side, located above, below, left, and right respectively. The upper and lower surfaces of the encapsulation layer 60 are positioned opposite each other, while the left and right sides are positioned opposite each other. The encapsulation layer 60 completely encapsulates the ceramic body 10, the inner electrode layer, and the interconnect structure, while partially encapsulating the lead-out electrodes, such that one surface of the first lead-out electrode 40a and one surface of the second lead-out electrode 40b are exposed on the lower surface of the encapsulation layer 60, and all three are approximately on the same horizontal plane. Thus, through the design of the encapsulation layer 60, the internal wiring can be made extremely small, without the need for large metal sheets or wires. Simultaneously, the ceramic body 10, the inner electrode layer, the interconnect structure, and some of the lead-out electrodes are isolated from the external environment and well protected. In one embodiment, the encapsulation layer 60 may be made of epoxy resin, silicone resin, polyimide resin, and / or other engineering plastics.

[0063] Furthermore, to reduce contact thermal resistance and improve soldering strength, the first lead electrode 40a and the second lead electrode 40b exposed on the lower surface of the encapsulation layer 60 can be covered with an outer electrode layer. That is, the first outer electrode layer 50a and the second outer electrode layer 50b can respectively cover the exposed first lead electrode 40a and the exposed second lead electrode 40b. Taking the bottom view area of ​​the first lead electrode 40a exposed on the lower surface of the encapsulation layer 60 as 100%, the area covered by the first outer electrode layer 50a is 110% to 130%. Similarly, taking the bottom view area of ​​the second lead electrode 40b exposed on the lower surface of the encapsulation layer 60 as 100%, the area covered by the second outer electrode layer 50b is 110% to 130%. In one embodiment, the material of the outer electrode layer can be selected from the group consisting of nickel (Ni), tin (Sn), and combinations thereof.

[0064] To better understand this invention, please continue to refer to... Figures 3a to 3d The production process.

[0065] Please refer to Figure 3a A ceramic body 10 is provided, and a first internal electrode layer 20a and a second internal electrode layer 20b are formed on the upper and lower surfaces of the ceramic body 10, respectively. Next, the ceramic body 10, the first internal electrode layer 20a, and the second internal electrode layer 20b are encapsulated with an encapsulation material (such as epoxy resin), such that the upper surface of the first internal electrode layer 20a is exposed while the second internal electrode layer 20b is completely covered. Finally, a first through-hole H1 is drilled on the left side of the encapsulation material using laser drilling, and a second through-hole H2 is drilled below the second internal electrode layer 20b, forming a first encapsulation layer 60a. The first through-hole H1 penetrates both the upper and lower surfaces of the first encapsulation layer 60a, while the second through-hole H2 extends approximately to the center of the second internal electrode layer 20b and exposes a portion of the surface of the second internal electrode layer 20b. The upper surface of the first internal electrode layer 20a is approximately flush with the upper surface of the first encapsulation layer 60a.

[0066] Please refer to Figure 3b Metal is plated into the first through-hole H1 and the second through-hole H2 using electroplating to form a plating through-hole (PTH). Since the upper surface of the first inner electrode layer 20a is approximately flush with the upper surface of the first encapsulation layer 60a, the metal plating can be smoothly plated onto the upper surfaces of the first inner electrode layer 20a and the first encapsulation layer 60a and connected to the plating in the first through-hole H1 to form the first interconnect structure 30a. In the second through-hole H2, the metal plating tapers from bottom to top and connects to the second inner electrode layer 20b to form the second interconnect structure 30b.

[0067] Please refer to Figure 3cThe first interconnect structure 30a is covered with the same encapsulation material to form a second encapsulation layer 60b. Thus, the second encapsulation layer 60b covers the ceramic body 10, the inner electrode layers (i.e., the first inner electrode layer 20a and the second inner electrode layer 20b), and part of the interconnect structure (i.e., the first interconnect structure 30a and the second interconnect structure 30b), exposing only the two ends extending from the first interconnect structure 30a and the second interconnect structure 30b to the lower surface of the second encapsulation layer 60b. Furthermore, the aforementioned two ends are substantially flush.

[0068] Please refer to Figure 3d The first lead electrode 40a and the second lead electrode 40b are aligned and soldered to the two exposed ends of the aforementioned first interconnect structure 30a and second interconnect structure 30b, respectively. To reduce the complexity of component design and selection, the second lead electrode 40b can be composed of a metal plating and a metal sheet, and the aforementioned metal sheet is the same as that of the first lead electrode 40a. That is, the first lead electrode 40a is a metal sheet with a rectangular cross-section, and the metal sheet in the second lead electrode 40b can also be a metal sheet with a rectangular cross-section, and both have the same material and size. In this way, a metal plating can be first applied to the exposed end face of the second interconnect structure 30b, and this metal plating can be extended along the z-axis in a direction away from the first lead electrode 40a to the lower surface of the second encapsulation layer 60b, and then the metal sheet can be soldered onto it to form a second lead electrode 40b with an inverted L shape. Finally, the lead-out electrodes are further encapsulated using the same encapsulation material, and the exposed portions of the first lead-out electrode 40a and the second lead-out electrode 40b are covered by the first outer electrode layer 50a and the second outer electrode layer 50b, forming a structure as shown below. Figure 2 The structure shown.

[0069] This invention may have different embodiments; please refer to further details. Figure 4 and Figure 5 .

[0070] Figure 4 A cross-sectional view of a ceramic thermistor 300 according to a second embodiment of the present invention is shown. Figure 4 Ceramic thermistor 300 and Figure 2 The main difference between the ceramic thermistor 200 and the previous one lies in the number of ceramic bodies and the corresponding modified interconnect structure. The ceramic thermistor 300 has two ceramic bodies connected in parallel, and the interconnect structure further includes a third interconnect structure 30c. Specific details are as follows.

[0071] The ceramic thermistor 300 includes a ceramic body assembly, an inner electrode layer, an interconnect structure, lead-out electrodes, an encapsulation layer 60, and an outer electrode layer. The ceramic body assembly has a first ceramic body 10a and a second ceramic body 10b stacked below the first ceramic body 10a. The first ceramic body 10a and the second ceramic body 10b are made of the same material and have the same dimensions. In another embodiment, the first ceramic body 10a and the second ceramic body 10b are made of different materials and have the same or different dimensions. The inner electrode layer has a first inner electrode layer 20a, a second inner electrode layer 20b, a third inner electrode layer 20c, and a fourth inner electrode layer 20d. The first inner electrode layer 20a and the second inner electrode layer 20b respectively cover the opposite upper and lower surfaces of the first ceramic body 10a, while the third inner electrode layer 20c and the fourth inner electrode layer 20d respectively cover the opposite upper and lower surfaces of the second ceramic body 10b, such that the second inner electrode layer 20b faces the third inner electrode layer 20c.

[0072] The interconnect structure has a first interconnect structure 30a, a second interconnect structure 30b, and a third interconnect structure 30c. The first interconnect structure 30a is connected between the second inner electrode layer 20b and the third inner electrode layer 20c. The second interconnect structure 30b is connected to the fourth inner electrode layer 20d. The third interconnect structure 30c is connected to the first inner electrode layer 20a. Similarly, the first interconnect structure 30a, the second interconnect structure 30b, and the third interconnect structure 30c further extend below the fourth inner electrode layer 20d. Specific details are as follows: The first interconnect structure 30a directly contacts the second inner electrode layer 20b and the third inner electrode layer 20c, extends along the z-axis flatly against the second inner electrode layer 20b and the third inner electrode layer 20c, and extends beyond the lower surface of the first ceramic body 10a and the upper surface of the second ceramic body 10b, and then continues to extend downward along the y-axis sequentially beyond the third inner electrode layer 20c, the second ceramic body 10b, and the fourth inner electrode layer 20d. The aforementioned z-axis is approximately parallel to the second inner electrode layer 20b and the third inner electrode layer 20c, while the y-axis is approximately perpendicular to the second inner electrode layer 20b and the third inner electrode layer 20c. The second interconnect structure 30b extends downward from the fourth inner electrode layer 20d along the y-axis and has a gradually widening cross-sectional profile, facilitating subsequent connection with the lead-out electrodes. The third interconnect structure 30c is flat against the first inner electrode layer 20a along the z-axis and extends beyond the upper surface of the first ceramic body 10a in a direction away from the first interconnect structure 30a, and then continues to extend downward along the y-axis sequentially beyond the first inner electrode layer 20a, the first ceramic body 10a, the second inner electrode layer 20b, the first interconnect structure 30a, the third inner electrode layer 20c, the second ceramic body 10b, and the fourth inner electrode layer 20d. The position above the first inner electrode layer 20a is defined as the upper side, and the position below the fourth inner electrode layer 20d is defined as the lower side. Thus, the three ends of the first interconnect structure 30a, the second interconnect structure 30b, and the third interconnect structure 30c extending from the inner electrode layer are roughly flush and all designed to be located on the same side, i.e., the lower side. That is to say, the contacts of the first interconnect structure 30a, the second interconnect structure 30b, and the third interconnect structure 30c are all located on the same side.

[0073] The lead-out electrode has a first lead-out electrode 40a and a second lead-out electrode 40b. The first lead-out electrode 40a is connected to a first interconnect structure 30a, while the second lead-out electrode 40b is connected to a second interconnect structure 30b and a third interconnect structure 30c. Furthermore, the lead-out electrodes extend downwards away from the interconnect structures. The second lead-out electrode 40b has a T-shaped cross-section, meaning it consists of a wider upper half and a narrower lower half, with the lower half aligned with and connected to the center of the upper half. Specifically, to improve fault tolerance and avoid short circuits, the side length of the upper half along the z-axis is greater than the side length of the lower half along the z-axis. Thus, the second interconnect structure 30b and the third interconnect structure 30c are respectively connected to the left and right ends of the upper half of the second lead-out electrode 40b. Similarly, the upper half of the second lead-out electrode 40b can be a metal plating layer, while the lower half of the second lead-out electrode 40b can be a metal sheet. Thus, the lower half of the second lead-out electrode 40b is the same as the first lead-out electrode 40a. Of course, in another embodiment, the second lead electrode 40b is an integrally formed metal sheet.

[0074] In the ceramic thermistor 300, the material of the inner electrode layer, the coverage area of ​​the inner electrode layer and the spacing G2 of the inner electrode layer, the material of the interconnect structure, the contact area between the interconnect structure and the inner electrode layer, the material of the lead electrode, the material of the outer electrode layer, the coverage area of ​​the encapsulation layer 60, the material of the encapsulation layer 60 and the configuration, size and material of other identical components can all be as described above, and will not be elaborated here.

[0075] Figure 5 A cross-sectional view showing a ceramic thermistor 400 according to a third embodiment of the present invention. Figure 5 400 ceramic thermistor and Figure 2 The main difference between the ceramic thermistor 200 and the previous one lies in the number of ceramic bodies and the corresponding modified interconnection structure. The ceramic thermistor 400 has two ceramic bodies connected in series. Specific details are as follows.

[0076] The ceramic thermistor 400 includes a ceramic body assembly, an inner electrode layer, an interconnect structure, lead-out electrodes, an encapsulation layer 60, and an outer electrode layer. The ceramic body assembly has a first ceramic body 10a and a second ceramic body 10b stacked below the first ceramic body 10a. The first ceramic body 10a and the second ceramic body 10b are made of the same material and have the same dimensions. In another embodiment, the first ceramic body 10a and the second ceramic body 10b are made of different materials and have the same or different dimensions. The inner electrode layer has a first inner electrode layer 20a, a second inner electrode layer 20b, a third inner electrode layer 20c, and a fourth inner electrode layer 20d. The first inner electrode layer 20a and the second inner electrode layer 20b respectively cover the opposite upper and lower surfaces of the first ceramic body 10a, while the third inner electrode layer 20c and the fourth inner electrode layer 20d respectively cover the opposite upper and lower surfaces of the second ceramic body 10b, and the second inner electrode layer 20b directly contacts the third inner electrode layer 20c.

[0077] The interconnect structure includes a first interconnect structure 30a and a second interconnect structure 30b, which are respectively connected to the first inner electrode layer 20a and the fourth inner electrode layer 20d, and extend below the fourth inner electrode layer 20d. The first interconnect structure 30a is flatly attached to the first inner electrode layer 20a along the z-axis, and extends beyond the upper surface of the first ceramic body 10a, and then continues to extend downward along the y-axis, sequentially extending beyond the first inner electrode layer 20a, the first ceramic body 10a, the second inner electrode layer 20b, the third inner electrode layer 20c, the second ceramic body 10b, and the fourth inner electrode layer 20d. The second interconnect structure 30b extends downward along the y-axis from the fourth inner electrode layer 20d and has a gradually widening cross-sectional profile, facilitating subsequent connection with the lead-out electrodes. The position above the first inner electrode layer 20a is defined as the upper side, and the position below the fourth inner electrode layer 20d is defined as the lower side. Thus, the two ends of the first interconnect structure 30a and the second interconnect structure 30b extending from the inner electrode layers are approximately flush and designed to be located on the same side, i.e., the lower side. That is, the contacts of the first interconnection structure 30a and the contacts of the second interconnection structure 30b are both located on the same side.

[0078] In the ceramic thermistor 400, the material of the inner electrode layer, the coverage area of ​​the inner electrode layer and the spacing G2 of the inner electrode layer, the material of the interconnect structure, the contact area between the interconnect structure and the inner electrode layer, the material of the lead electrode, the material of the outer electrode layer, the coverage area of ​​the encapsulation layer 60, the material of the encapsulation layer 60 and the configuration, size and material of other identical components can all be as described above, and will not be elaborated here.

[0079] To further illustrate the present invention, please refer to the data in Tables 1, 2, 3 and 4 below.

[0080] Table 1

[0081]

[0082]

[0083] R1 refers to the first trace element. R2 refers to the second trace element. ρ refers to volume resistivity. T c This refers to the Curie point, defined as the temperature at which the electrical resistance at 25°C doubles. To meet industry requirements, the Curie point (T...) c The desired temperature range is between approximately 85°C and approximately 90°C. 125 / R 25 Rs refers to the rate of increase in resistance, defined as the ratio of the resistance of the ceramic body 10 at 125°C to its resistance at 25°C. That is, the ceramic body has a first resistance value at 25°C and a second resistance value at 125°C. The ratio of the second resistance value to the first resistance value is Rs. 125 / R 25 .

[0084] The preparation method of ceramic body 10 is described below.

[0085] First, barium carbonate (BaCO3), strontium carbonate (SrCO3), calcium carbonate (CaCO3), titanium dioxide (TiO2), manganese dioxide (MnO2), and trivalent and pentavalent semiconductor elements are mixed with a dispersant and water, and then mixed using a ball mill to form a slurry. The aforementioned trivalent and pentavalent semiconductor elements are selected from the group consisting of ytterbium (Y), lanthanum (La), cerium (Ce), antimony (Sb), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), tantalum (Ta), erbium (Er), thulium (Tm), and combinations thereof. After filtration and drying, the slurry is calcined at a temperature of 800°C to 1000°C to form ceramic powder. The ceramic powder is mixed with a binder and then granulated to form numerous ceramic particles. These ceramic particles were then hot-pressed into plate-shaped ceramic blanks, which were subsequently placed in a sintering furnace and sintered under atmospheric conditions to form ceramic body 10. The sintering temperature was 1320℃, and the temperature was held for one hour. The oxygen content in the sintering atmosphere in the sintering furnace was 21%. Ceramic body 10 was then subjected to elemental analysis and electrical property testing, and the results are shown in Table 1.

[0086] As shown in Table 1, the ceramic body 10 comprises a first component and a second component.

[0087] In the first component, the total mole count of barium, strontium, calcium, and the first trace element is 100%, and the proportions of strontium, calcium, and the first trace element are adjusted. Strontium and barium are generally used to adjust the Curie point, while calcium can be used as a grain refiner for ceramic particles. In the second component, the total mole count of titanium, manganese, and the second trace element is 100%, and the proportions of manganese and the second trace element are adjusted. Manganese can adjust the degree of resistance jump.

[0088] Please refer to Comparative Example C1 and Examples E1 to E6. The main difference between Comparative Example C1 and Examples E1 to E6 lies in the ratio of strontium and calcium. The ratios of strontium and calcium in Examples E1 to E6 were adjusted to 20% and 4.5% or more, respectively, while the ratios of strontium and calcium in Comparative Example C1 were 15% and 3%, respectively. The results show that the volume resistivity (ρ) of Examples E1 to E6 can be significantly reduced to below 9.03 Ω·cm; the Curie point (T) c The temperature remains between 85°C and 91°C; while the resistivity jump rate (R0) remains between 85°C and 91°C. 125 / R 25 The resistivity of the latter is generally above 43. In contrast, the volume resistivity (ρ) of comparative example C1 is much higher than 10 Ω·cm, and the resistivity jump rate (R) is also higher. 125 / R 25 The value is also relatively low.

[0089] Please refer to Examples E7 to E9 and Comparative Examples C2 to C3. The ratios of strontium and calcium in Examples E7 to E9 were maintained within the same range as in Examples E1 to E6, while the ratio of the first trace element was slightly increased. The main difference between Comparative Example C2 and Examples E7 to E9 is that the strontium ratio in Comparative Example C2 is slightly higher, at 30%. The main difference between Comparative Example C3 and Examples E7 to E9 is that the ratio of the first trace element in Comparative Example C3 is slightly higher, at 0.2%. The results show that Examples E7 to E9 all maintained a low resistance state below 10 Ω·cm; the Curie point (T... c The temperature is around 90℃; while the resistivity jump rate (R) 125 / R 25 The resistivity is approximately above 40. In contrast, although the volume resistivity (ρ) of comparative example C2 is lower, its Curie point (T) is higher. c The temperature is too low and does not meet the required protection temperature. As for Comparative Example C3, its volume resistivity (ρ) is too high, making it difficult for current to pass through when the component is not operating.

[0090] Please refer to Examples E10 to E11 and Comparative Example C4. The main difference between Examples E10 to E11 and Comparative Example C4 lies in the proportion of manganese. The proportion of manganese in Examples E10 to E11 is 0.02% to 0.03%, while the proportion of manganese in Comparative Example C4 is higher, at 0.04%. The results show that Examples E10 to E11 have a lower volume resistivity (ρ) and a higher resistance jump rate (R) than the aforementioned examples. 125 / R 25 The volume resistivity (ρ) of Comparative Example C4 is much higher, at 23.8 Ω·cm, which will affect the current flow of the protected device under normal operation.

[0091] Please refer to Example E12 and Comparative Example C5. The main difference between Example E12 and Comparative Example C5 lies in the proportion of the second trace element. The proportion of the second trace element in Example E12 is 0.03%, while the proportion of the second trace element in Comparative Example C5 is lower, at 0.01%. The results show that Example E12 still maintains a lower volume resistivity (ρ), while the volume resistivity (ρ) of Comparative Example C5 is too high.

[0092] Please refer to Examples E13 and Comparative Example C6. Compared with Examples E12 and Comparative Example C5, Examples E13 and Comparative Example C6 compared the effect of the second trace element at a lower manganese ratio (0.01%). The proportion of the second trace element in Example E13 was 0.04%, while the proportion of the second trace element in Comparative Example C5 was higher, at 0.05%. The results show that when the manganese ratio is 0.01%, a more desirable low volume resistivity (ρ) can be obtained with a second trace element ratio of 0.04%.

[0093] In the aforementioned sintering process, this invention further includes testing the adjustment of the oxygen content in the sintering atmosphere. Please continue to refer to Table 2 and... Figure 6 .

[0094] Table 2

[0095]

[0096]

[0097] like Figure 6 The sintering time was 1 hour, and the main temperature points in the sintering process were T1, T2, T3, T4, and T5, corresponding to 500℃, 1320℃, 1320℃, 800℃, and 300℃, respectively. The temperature rise range was from 500℃ to 1320℃ (T1-T2); the high temperature range was from 1320℃ to 1320℃ (T2-T3); and the cooling ranges were from 1320℃ to 800℃ (T3-T4) and from 800℃ to 300℃ (T4-T5). In this experiment, it was found that adjusting the oxygen content could further reduce the volume resistivity (ρ) under the composition ratio of the aforementioned embodiments.

[0098] Please refer to Examples E7, E10, and E12 and Comparative Examples C7 to C9. In these groups, the same oxygen content was maintained in the heating, high-temperature, and cooling stages. The oxygen content of Examples E7, E10, and E12 was 21%, while the oxygen content of Comparative Examples C7 to C9 was 3%. The results show that the oxygen content in Comparative Examples C7 to C9 was too low, preventing the ceramic particles in the ceramic body 10 from forming a sufficient oxide layer to produce the characteristic of a resistance jump. Although the volume resistivity (ρ) was low, the lack of a resistance jump characteristic prevented it from functioning as an overcurrent protection element.

[0099] Please continue to refer to Examples E14 to E19 and Comparative Examples C10 to C12. In these groups, the oxygen content in the heating stage, the high-temperature stage, and the first part of the cooling stage (T3-T4) was adjusted to be below 21%, while the oxygen content in the latter part of the cooling stage (T4-T5) was maintained at a high oxygen content of 21%. More specifically, in Examples E14 to E19, the oxygen content in the heating stage, the high-temperature stage, and the first part of the cooling stage (T3-T4) showed a high-low-high trend, with the oxygen content in the heating stage all above 7% and the oxygen content in the first part of the cooling stage (T3-T4) being 15%. In contrast, in Comparative Examples C10 to C12, the oxygen content in the heating stage, the high-temperature stage, and the first part of the cooling stage (T3-T4) showed a low-low-high trend, with the oxygen content in the heating stage and the first part of the cooling stage (T3-T4) all below 5%. The results showed that the volume resistivity (ρ) of Examples E14 to E19 could be adjusted to be much lower than 10 Ω·cm; the Curie point was 85°C or 86°C; and the resistivity jump rate (R) was... 125 / R 25 The values ​​ranged from 15.9 to 21.3. In contrast, comparative examples C10 to C12, while having similar volume resistivity (ρ) and Curie point, exhibited significantly higher resistivity jumps (R0). 125 / R 25 If the current is too low, it will not be able to produce a good current cut-off effect when the component is operating.

[0100] Table 3

[0101]

[0102] Table 4

[0103]

[0104] In Tables 3 and 4, the ceramic bodies prepared above were tested with different structural designs. Groups E20 to E25 are Examples E20 to E25 of the present invention. Groups C13 and C14 are Comparative Examples C13 and C14, respectively. The ceramic bodies of Examples E20 to E22 and Comparative Example C13 are all derived from the aforementioned Example E12, wherein Examples E20 to E22 were prepared as follows: Figure 2 The ceramic thermistor 200 shown is used, while comparative example C13 is fabricated as follows: Figure 1a and Figure 1b The ceramic thermistor 100 shown. The ceramic bodies of Examples E23 to E25 and Comparative Example C14 are all derived from the aforementioned Example E17, wherein Examples E23 to E25 are fabricated as follows: Figure 2 The ceramic thermistor 200 shown is used, while comparative example C14 is fabricated as follows: Figure 1a and Figure 1bThe ceramic thermistor 100 is shown. In Table 3, the length and thickness of Examples E20 to E25 correspond to the length L2 and thickness T2 of the ceramic thermistor 200; while the length, width, and thickness of Comparative Examples C13 and C14 correspond to the length L1, width W1, and thickness T1 of the ceramic thermistor 100. In terms of the size of the ceramic thermistor, Examples E20 to E25 are generally made the same, while Comparative Examples C13 and C14 are smaller than Examples E20 to E25.

[0105] Please refer to Table 4. The inner electrode area refers to the top-view or bottom-view area of ​​a single inner electrode, i.e., the top-view area of ​​the first inner electrode layer 20a or the bottom-view area of ​​the second inner electrode layer 20b. The inner electrode spacing refers to spacing G1 or spacing G2. Spacing / Area is the ratio obtained by dividing the inner electrode spacing by the inner electrode area.

[0106] Please refer to Examples E20 to E22 and Comparative Example C13. The volume resistivity (ρ) of Examples E20 to E22 and Comparative Example C13 are roughly in the same range, but Examples E20 to E22 have a much lower resistance value than Comparative Example C13. The resistance value of Examples E20 to E22 is 122Ω to 148Ω, while the resistance value of Comparative Example C13 is 324Ω. The main reason is that, in addition to significantly reducing the internal electrode spacing, the present invention also adjusts the internal electrode area, and the ratio between the two is much lower than 3. As shown in Table 3, the internal electrode spacing of Examples E20 to E22 is 0.167mm to 0.181mm, and the internal electrode area is 0.091mm². 2 Up to 0.109mm 2 Accordingly, the spacing / area ratio of embodiments E20 to E22 is controlled to be within the range of 1.6 to 2.

[0107] Please refer to Examples E23 to E25 and Comparative Example C14. Similarly, the volume resistivity (ρ) of Examples E23 to E25 and Comparative Example C14 are approximately in the same range, but Examples E23 to E25 have resistance values ​​significantly lower than Comparative Example C14. The resistance values ​​of Examples E23 to E25 are 46Ω to 61Ω, while the resistance value of Comparative Example C14 is 141Ω. In addition to significantly reducing the internal electrode spacing, Examples E23 to E25 of the present invention also incorporate an internal electrode area adjustment, with the ratio between the two being significantly lower than 3. As shown in Table 3, the internal electrode spacing of Examples E23 to E25 is 0.162mm to 0.178mm, and the internal electrode area is 0.092mm². 2 Up to 0.111mm 2Accordingly, the spacing / area ratio of embodiments E20 to E22 is controlled within the range of 1.4 to 1.9. Considering the influence of error and the allowable range of variation, the internal electrode area of ​​the present invention can be 0.08 mm². 2 With 0.13mm 2 The range between these parameters can be adjusted; the spacing between the inner electrodes can be adjusted between 0.15 mm and 0.19 mm; and the ratio of spacing to area is controlled to be between 1.4 and 2.

[0108] Furthermore, as mentioned above, the packaging structure employed in this invention allows for miniaturization of internal wiring. This enables the ceramic body to be designed to be smaller, while good electrical conductors can extend within the packaging structure and increase the conductive area, further reducing component resistance.

[0109] The technical content and features of this invention have been disclosed above. However, those skilled in the art may still make various substitutions and modifications that do not depart from the spirit of this invention based on the teachings and disclosures. Therefore, the scope of protection of this invention should not be limited to what is disclosed in the embodiments, but should include various substitutions and modifications that do not depart from this invention, and is covered by the following claims.

Claims

1. A ceramic thermistor, comprising: A ceramic body having an upper surface and a lower surface opposite to the upper surface; An inner electrode layer, having a first inner electrode layer and a second inner electrode layer respectively covering the upper surface and the lower surface of the ceramic body; An interconnect structure having a first interconnect structure and a second interconnect structure respectively connecting the first inner electrode layer and the second inner electrode layer, and extending below the second inner electrode layer; and An encapsulation layer covers the ceramic body, the inner electrode layer, and the interconnect structure, such that a portion of the first interconnect structure and a portion of the second interconnect structure are located below the second inner electrode layer within the encapsulation layer.

2. The ceramic thermistor element according to claim 1, wherein: The first inner electrode layer is separated from the second inner electrode layer by a distance; The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area respectively when viewed from above and from below; and The ratio obtained by dividing the spacing by the first surface area or the second surface area is less than 3.

3. The ceramic thermistor according to claim 2, wherein the spacing is between 0.15 mm and 0.19 mm, and the first surface area or the second surface area is between 0.08 mm². 2 With 0.13mm 2 between.

4. The ceramic thermistor according to claim 1 further includes a lead electrode, having a first lead electrode and a second lead electrode respectively connected to the first interconnect structure and the second interconnect structure, and extending downward in a direction away from the interconnect structure.

5. The ceramic thermistor of claim 4, wherein the encapsulation layer covers the lead-out electrode, thereby exposing only a portion of the first lead-out electrode and a portion of the second lead-out electrode on the same side.

6. The ceramic thermistor according to claim 5 further comprises an external electrode layer having a first external electrode layer and a second external electrode layer respectively covering the exposed first lead electrode and the exposed second lead electrode.

7. The ceramic thermistor element according to claim 1, wherein the ceramic body comprises a first component and a second component, wherein: The first component contains barium, strontium, calcium, and a first trace element; The second component contains titanium, manganese, and a second trace element; The first and second trace elements are selected from the group consisting of ytterbium, lanthanum, cerium, antimony, praseodymium, neodymium, samarium, europium, gadolinium, tantalum, erbium, thulium, and combinations thereof; and The volume resistivity of this ceramic body is less than 15 Ω·cm.

8. The ceramic thermistor element according to claim 7, wherein the total mole count of barium, strontium, calcium, and the first trace element is 100%, and: Strontium accounts for 20% to 25%; Calcium accounts for 4.5% to 5%; and The first trace element accounts for 0.13% to 0.17%, thereby giving the ceramic body a Curie temperature of 80°C to 130°C.

9. The ceramic thermistor element according to claim 7, wherein the total mole count of titanium, manganese, and the second trace element is 100%, and: Manganese accounts for 0.01% to 0.03%; and This second trace element accounts for 0.02% to 0.04%.

10. The ceramic thermistor according to claim 9, wherein: The ceramic body has a first resistance value at 25°C; The ceramic body has a second resistance value at 125°C; and The ratio of the second resistance value to the first resistance value is 10 or more.

11. A ceramic thermistor, comprising: A ceramic body assembly having a first ceramic body and a second ceramic body stacked below the first ceramic body; An inner electrode layer has a first inner electrode layer, a second inner electrode layer, a third inner electrode layer and a fourth inner electrode layer, wherein the first inner electrode layer and the second inner electrode layer respectively cover an upper surface and a lower surface opposite to each other of the first ceramic body, and the third inner electrode layer and the fourth inner electrode layer respectively cover an upper surface and a lower surface opposite to each other of the second ceramic body, such that the second inner electrode layer faces the third inner electrode layer; An interconnect structure having a first interconnect structure, a second interconnect structure, and a third interconnect structure, wherein the first interconnect structure is connected between the second inner electrode layer and the third inner electrode layer, the second interconnect structure is connected to the fourth inner electrode layer, and the third interconnect structure is connected to the first inner electrode layer, and the first, second, and third interconnect structures further extend below the fourth inner electrode layer; and An encapsulation layer covers the ceramic body assembly, the inner electrode layer, and the interconnect structure, such that a portion of the first interconnect structure, a portion of the second interconnect structure, and a portion of the third interconnect structure are located below the fourth inner electrode layer within the encapsulation layer.

12. The ceramic thermistor according to claim 11, wherein: The first inner electrode layer is separated from the second inner electrode layer by a distance; The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area respectively when viewed from above and from below; and The ratio obtained by dividing the spacing by the first surface area or the second surface area is less than 3.

13. The ceramic thermistor of claim 11 further comprises a lead-out electrode having a first lead-out electrode and a second lead-out electrode, wherein the first lead-out electrode is connected to the first interconnect structure, and the second lead-out electrode is connected to the second interconnect structure and the third interconnect structure, and extends downward in a direction away from the interconnect structure.

14. The ceramic thermistor of claim 13, wherein the encapsulation layer covers the lead-out electrode, thereby exposing only a portion of the first lead-out electrode and a portion of the second lead-out electrode on the same side.

15. The ceramic thermistor of claim 14, further comprising an external electrode layer having a first external electrode layer and a second external electrode layer respectively covering the exposed first lead electrode and the exposed second lead electrode.

16. A ceramic thermistor, comprising: A ceramic body assembly having a first ceramic body and a second ceramic body stacked below the first ceramic body; An inner electrode layer has a first inner electrode layer, a second inner electrode layer, a third inner electrode layer and a fourth inner electrode layer, wherein the first inner electrode layer and the second inner electrode layer respectively cover an upper surface and a lower surface opposite to each other of the first ceramic body, and the third inner electrode layer and the fourth inner electrode layer respectively cover an upper surface and a lower surface opposite to each other of the second ceramic body, and the second inner electrode layer is in direct contact with the third inner electrode layer; An interconnect structure having a first interconnect structure and a second interconnect structure respectively connecting the first inner electrode layer and the fourth inner electrode layer, and extending below the fourth inner electrode layer; and An encapsulation layer covers the ceramic body assembly, the inner electrode layer, and the interconnect structure, such that a portion of the first interconnect structure and a portion of the second interconnect structure are located below the fourth inner electrode layer within the encapsulation layer.

17. The ceramic thermistor according to claim 16, wherein: The first inner electrode layer is separated from the second inner electrode layer by a distance; The first inner electrode layer and the second inner electrode layer have a first surface area and a second surface area respectively when viewed from above and from below; and The ratio obtained by dividing the spacing by the first surface area or the second surface area is less than 3.

18. The ceramic thermistor of claim 17 further comprises a lead-out electrode having a first lead-out electrode and a second lead-out electrode respectively connected to the first interconnect structure and the second interconnect structure, and extending downward in a direction away from the interconnect structure.

19. The ceramic thermistor of claim 18, wherein the encapsulation layer covers the lead-out electrode, thereby exposing only a portion of the first lead-out electrode and a portion of the second lead-out electrode on the same side.

20. The ceramic thermistor of claim 19 further comprises an external electrode layer having a first external electrode layer and a second external electrode layer respectively covering the exposed first lead electrode and the exposed second lead electrode.

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