Ceramic thermal element

Abstract

A ceramic thermistor includes a ceramic body, an inner electrode layer, and an outer electrode layer. The ceramic body has a positive temperature coefficient and includes a top surface, a bottom surface, a first end surface, and a second end surface. The top surface and the bottom surface are disposed opposite each other, while the first end surface and the second end surface are disposed opposite each other and connected to the top surface and the bottom surface. The inner electrode layers are disposed at both ends of the top surface, and the inner electrode layers at both ends are separated by a distance. The outer electrode layer covers the inner electrode layers.

Description

Technical Field

[0001] This invention relates to a ceramic thermistor, and more specifically, to a ceramic thermistor with low resistance and excellent resistance jump performance. Background Technology

[0002] The resistance of a known 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., above 10⁴ Ω), a phenomenon known as a "trip," thus cutting off the excessive current and protecting the battery or circuit components. Therefore, PTC elements 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. It is well known that PPTC elements do not readily return to their original resistance after tripping, exhibiting poor impedance hysteresis and low voltage tolerance. While CPTC elements generally withstand high voltages and their resistance can recover to a value close to their original value, their relatively high normal resistance results in poor conductivity, thus limiting their application range.

[0004] Furthermore, due to the material differences in the positive temperature coefficient (PTC) layers of the two devices, the structural designs of their internal electrodes also differ. The PTC layer of a PPTC device is primarily composed of polymer and conductive fillers. After mixing, the conductive polymer is pressed into a thin sheet, and then copper foil is placed on top and below the sheet and hot-pressed to form a three-layer structure. The copper foil can then be etched with different patterns to form the internal electrode of the PPTC device. The PTC layer of a CPTC device is primarily composed of ceramic materials. The ceramic material must first undergo a sintering process to form a conductive ceramic substrate, and then metal materials are printed and sintered to form the internal electrode. It should be understood that compared to the internal electrode of a PPTC device, the design freedom of the internal electrode of a CPTC device is lower, and standardized designs are widely available in the industry. Please refer to [reference needed]. Figure 1A and Figure 1B .

[0005] Figure 1A Showing a 3D diagram of a known CPTC component, while Figure 1B show Figure 1A The image shows a cross-sectional view of a CPTC element along line segment AA. A known CPTC element comprises a ceramic body 1 (i.e., the aforementioned conductive ceramic substrate), an inner electrode layer 2, and an outer electrode layer 3. The inner electrode layer 2 is formed on both end faces of the ceramic body 1, while the outer electrode layer 3 covers the inner electrode layer 2 and further encloses all exposed areas at both ends of the ceramic body 1. It can be noted that placing the inner electrode layer 2 at both ends results in excessively large distances between them, causing excessively high resistance when the element is not activated (i.e., not triggered). Shortening the ceramic body 1 to reduce resistance has dimensional limitations; besides failing to achieve satisfactory low resistance performance, it is more likely to cause unintended changes in other electrical characteristics.

[0006] In view of this, there is an urgent need to develop a low-resistance ceramic thermistor that also performs well in other electrical characteristics. Summary of the Invention

[0007] The purpose of this invention is to provide a ceramic thermistor to solve at least one of the above-mentioned problems.

[0008] According to one embodiment of the present invention, a ceramic thermistor includes a ceramic body, an inner electrode layer, and an outer electrode layer. The ceramic body has a positive temperature coefficient and includes a top surface, a bottom surface, a first end surface, and a second end surface. The top surface and the bottom surface are disposed opposite each other, while the first end surface and the second end surface are disposed opposite each other and connected to the top surface and the bottom surface. The inner electrode layer is disposed at both ends of the top surface, and the inner electrode layers at both ends are separated by a gap. The outer electrode layer covers the inner electrode layer.

[0009] According to some embodiments, the ceramic body further includes a first side surface and a second side surface opposite to the first side surface, connecting the top surface, bottom surface, first end surface, and second end surface, thereby forming a hexahedron. An outer electrode layer extends and covers the first end surface and the second end surface, but does not cover the first side surface and the second side surface.

[0010] According to some embodiments, the ceramic thermistor further includes an insulating layer covering the top surface of the ceramic body. The insulating layer is disposed within the spacing between the inner electrode layers at both ends.

[0011] According to some embodiments, the inner electrode layer has an inner electrode top surface and a first sidewall. The inner electrode top surface is parallel to the top surface of the ceramic body, while the first sidewall extends perpendicularly from the inner electrode top surface to the top surface. An insulating layer extends to the first sidewall, thereby partially covering the insulating layer and the first sidewall with respect to the inner electrode layer.

[0012] According to some embodiments, the insulating layer completely covers the first sidewall of the inner electrode layer and extends further to the top surface of the inner electrode, thereby partially covering the insulating layer and the top surface of the inner electrode.

[0013] According to some embodiments, the inner electrode layer has an inner electrode top surface and a first sidewall. The inner electrode top surface is parallel to the top surface of the ceramic body, and the first sidewall extends perpendicularly from the inner electrode top surface to the top surface. An outer electrode layer covers the first sidewall and the inner electrode top surface of the inner electrode layer. An insulating layer extends to the outer electrode layer and further extends parallel to the first sidewall and covers the outer electrode layer.

[0014] According to some embodiments, the insulating layer further covers the bottom surface, the first side surface, and the second side surface of the ceramic body, so that only the insulating layer and the outer electrode layer of the ceramic thermistor are exposed to the external environment.

[0015] According to some embodiments, the spacing is 0.4 mm to 0.45 mm.

[0016] According to some embodiments, the inner electrode layer has a width extending toward the first end face and the second end face, and the width is 0.15 mm to 0.21 mm.

[0017] According to some embodiments, the material of the inner electrode layer does not contain titanium.

[0018] According to some embodiments, the material of the inner electrode layer is selected from the group consisting of nickel, chromium, nickel-chromium alloys, nickel-copper alloys, silver, aluminum, and combinations thereof.

[0019] 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 10 Ω·cm.

[0020] 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 85°C to 91°C.

[0021] According to some embodiments, the total moles of titanium, manganese and the second trace element are 100%, with manganese accounting for 0.01% to 0.03% and the second trace element accounting for 0.02% to 0.04%.

[0022] According to some embodiments, 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 10 or more.

[0023] According to one embodiment of the present invention, a ceramic thermistor includes a ceramic body, an inner electrode layer, and an outer electrode layer. The ceramic body has a positive temperature coefficient and includes a top surface, a bottom surface, a first end surface, and a second end surface. The top surface and the bottom surface are disposed opposite each other, while the first end surface and the second end surface are disposed opposite each other and connected to the top surface and the bottom surface. The inner electrode layer is disposed at both ends of the top surface, and the inner electrode layers at both ends are separated by a gap. The outer electrode layer covers the inner electrode layer and the top surface of the ceramic body, and does not extend to the first end surface and the second end surface.

[0024] According to some embodiments, the ceramic body further includes a first side surface and a second side surface opposite to the first side surface, connecting the top surface, bottom surface, first end surface, and second end surface, thereby forming a hexahedron. The outer electrode layer does not cover the first side surface and the second side surface.

[0025] According to some embodiments, an insulating layer covers the top surface of the ceramic body. The insulating layer is disposed within the spacing of the inner electrode layers at both ends.

[0026] According to some embodiments, the inner electrode layer has an inner electrode top surface and a first sidewall. The inner electrode top surface is parallel to the top surface of the ceramic body, while the first sidewall extends perpendicularly from the inner electrode top surface to the top surface. An insulating layer extends to the first sidewall, thereby partially covering the insulating layer and the first sidewall with respect to the inner electrode layer.

[0027] According to some embodiments, the insulating layer completely covers the first sidewall of the inner electrode layer and extends further to the top surface of the inner electrode, thereby partially covering the insulating layer and the top surface of the inner electrode.

[0028] According to some embodiments, the inner electrode layer has an inner electrode top surface and a first sidewall. The inner electrode top surface is parallel to the top surface of the ceramic body, and the first sidewall extends perpendicularly from the inner electrode top surface to the top surface. An outer electrode layer covers the first sidewall and the inner electrode top surface of the inner electrode layer. An insulating layer extends to the outer electrode layer and further extends parallel to the first sidewall and covers the outer electrode layer.

[0029] According to some embodiments, the insulating layer further covers the bottom surface, first side surface, second side surface, first end surface, and second end surface of the ceramic body.

[0030] According to some embodiments, the spacing is 0.4 mm to 0.45 mm.

[0031] According to some embodiments, the inner electrode layer has a width extending toward the first end face and the second end face, and the width is 0.15 mm to 0.21 mm.

[0032] According to some embodiments, the material of the inner electrode layer does not contain titanium.

[0033] According to some embodiments, the material of the inner electrode layer is selected from the group consisting of nickel, chromium, nickel-chromium alloys, nickel-copper alloys, silver, aluminum, and combinations thereof.

[0034] 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 10 Ω·cm.

[0035] 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 85°C to 91°C.

[0036] 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%.

[0037] According to some embodiments, 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 10 or more.

[0038] The beneficial effects of this invention are that the ceramic thermistor elements of this invention can all have low volume resistivity, suitable Curie point, and good resistance jump rate. Furthermore, the electrical properties can be further improved by adjusting the material composition of the ceramic body. Attached Figure Description

[0039] Figure 1A and Figure 1B The perspective view and cross-sectional view of a well-known ceramic positive temperature coefficient element are shown respectively;

[0040] Figure 2 A perspective view showing a first embodiment of the ceramic thermistor element of the present invention;

[0041] Figure 3A , Figure 3B and Figure 3C Display respectively Figure 2 Cross-sectional view, top view and front view of the ceramic thermistor;

[0042] Figure 3D show Figure 3A A magnified view of a section within the dashed box;

[0043] Figure 4 A perspective view showing a second embodiment of the ceramic thermistor element of the present invention;

[0044] Figure 5A , Figure 5B and Figure 5C Display respectively Figure 4 Cross-sectional view, top view and front view of the ceramic thermistor;

[0045] Figure 5D show Figure 5A A magnified view of a section within the dashed box;

[0046] Figures 6A to 7B Cross-sectional views showing various embodiments of the present invention; and

[0047] Figure 8 This displays the temperature curves during the sintering process.

[0048] The attached figures are labeled as follows:

[0049] 1.10 Ceramic Body

[0050] 11 Top surface

[0051] 12 Bottom

[0052] 13 First end face

[0053] 14 Second end face

[0054] 15 First side view

[0055] 16 Second side view

[0056] 2.20 Inner Electrode Layer

[0057] 21 Internal electrode top surface

[0058] 22 Inner electrode bottom surface

[0059] 23 First sidewall

[0060] 24 Second sidewall

[0061] 3.30 outer electrode layer

[0062] 40 insulation layers

[0063] 100 and 200 ceramic thermistors

[0064] G spacing

[0065] W width Detailed Implementation

[0066] To make the above and other technical contents, features and advantages of the present invention more apparent and understandable, relevant embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0067] Please refer to Figures 2 to 3DThis image shows various views of a first embodiment of the ceramic thermistor 100 of the present invention. The ceramic thermistor 100 of the present invention includes a ceramic body 10, an inner electrode layer 20, an outer electrode layer 30, and an insulating layer 40. The ceramic body 10 is a hexahedron with a positive temperature coefficient (i.e., a hexahedron including a top surface 11, a bottom surface 12, a first end surface 13, a second end surface 14, a first side surface 15, and a second side surface 16). Figure 2 In this process, the outer electrode layer 30 is located at both ends of the ceramic body 10 and extends from the top surface 11 and the bottom surface 12, covering the entire end face (i.e., the first end face 13 and the second end face 14) but not covering the first side face 15 and the second side face 16. The remaining parts of the ceramic body 10 exposed to the external environment are covered by the insulating layer 40. In this way, a ceramic thermistor 100 is formed with three sides of the outer electrode layer 30 covered at each end.

[0068] Please continue to refer to Figure 3A ,for Figure 2 A cross-sectional view of the ceramic thermistor 100 along line AA. To enable electrical conduction between the ceramic body 10 and an external power source, an inner electrode layer 20 with good ohmic contact must first be formed on it; therefore, the inner electrode layer 20 can also be called an ohmic contact electrode. The material of the inner electrode layer 20 can be selected from the group consisting of nickel (Ni), chromium (Cr), nickel-chromium alloy (Ni-Cralloy), nickel-copper alloy (Ni-Cu alloy), silver (Ag), aluminum (Al), and combinations thereof, and can be formed by printing, coating, vapor deposition, or other known film-forming methods. For example, a nickel-chromium alloy can be formed into a paste and printed on the surface, and then sintered to form the inner electrode layer 20. Furthermore, considering the applicability of the material, the material of the inner electrode layer 20 of the present invention does not include titanium. It should also be noted that, to shorten the current conduction distance, the inner electrode layer 20 of the present invention is not disposed on the first end face 13 and the second end face 14. More specifically, the inner electrode layer 20 is disposed at both ends of the top surface 11 and the bottom surface 12, and the inner electrode layers 20 at both ends are separated by a distance G. That is, the inner electrode layer 20 on the top surface 11 is divided into two independent blocks located at its two ends, separated from each other by at least a distance G; while the inner electrode layer 20 on the bottom surface 12 is divided into two independent blocks located at its two ends, separated from each other by at least a distance G. In other words, taking the left side of the cross-sectional view as an example, the inner electrode layer 20 extends to the right along the z-axis from the junction of the first end face 13 with the top surface 11 and the bottom surface 12; and taking the right side of the cross-sectional view as an example, the inner electrode layer 20 extends to the left along the z-axis from the junction of the second end face 14 with the top surface 11 and the bottom surface 12. Accordingly, the inner electrode layer 20 is only disposed on the top surface 11 and the bottom surface 12, and does not cover the first end face 13, the second end face 14, the first side face 15, and the second side face 16. It should be understood that the inner electrode layer 20 can be a single layer or multiple layers. In one embodiment, the inner electrode layer 20 is a multilayer structure, that is, multiple layers are stacked along the y-axis direction, wherein the materials of each layer may be the same or different.

[0069] To improve the weather resistance of the ceramic body 10 and the insulation of the non-electrical connection areas, the present invention further provides an insulating layer 40 within the spacing G of the inner electrode layers 20. The insulating material can be printed onto the areas without the inner electrode layers 20, and then sintered to form the insulating layer 40. In addition to the areas covered by the inner electrode layers 20, the insulating layer 40 covers the remaining areas of the top surface 11 and the bottom surface 12, and further covers the first side surface 15 and the second side surface 16 (see reference). Figure 2 Additionally, as previously mentioned, the present invention may include an outer electrode layer 30. The outer electrode layer 30 covers a portion of the insulating layer 40 and encapsulates the entire inner electrode layer 20. The outer electrode layer 30 can be formed by electroplating or chemical plating. For example, nickel (Ni) or tin (Sn) is plated onto the inner electrode layer 20, and the aforementioned nickel or tin layer constitutes the outer electrode layer 30. Of course, the outer electrode layer 30 can be a single layer or multiple layers. In one embodiment, the outer electrode layer 30 has a multilayer structure, wherein the materials of each layer can be the same or different.

[0070] To more clearly explain the configuration of the inner electrode layer 20, the outer electrode layer 30, and the insulating layer 40, please refer to [link / reference needed]. Figure 3D . Figure 3D show Figure 3A A partially enlarged view of the ceramic thermistor 100 within the dashed box. The inner electrode layer 20 has an inner electrode top surface 21, an inner electrode bottom surface 22, a first sidewall 23, and a second sidewall 24. The inner electrode top surface 21 is parallel to the top surface 11 of the ceramic body 10 and is disposed opposite to the inner electrode bottom surface 22. The first sidewall 23 and the second sidewall 24 are disposed opposite to each other and connect the inner electrode top surface 21 and the inner electrode bottom surface 22. That is, the first sidewall 23 extends vertically from the inner electrode top surface 21 to the top surface 11, and the second sidewall 24 also extends vertically from the inner electrode top surface 21 to the top surface 11. The inner electrode bottom surface 22 is substantially coplanar with the top surface 11 of the ceramic body 10, and the second sidewall 24 is substantially coplanar with the second end surface 14, such that the second sidewall 24 of the inner electrode layer 20 and the second end surface 14 of the ceramic body 10 are flush when viewed along the y-axis. Of course, in some embodiments, the second sidewall 24 may also be designed to be non-coplanar with the second end face 14 (not shown), so that the second sidewall 24 of the inner electrode layer 20 and the second end face 14 of the ceramic body 10 have a step difference when viewed along the y-axis. To avoid the influence of plating, moisture or other external factors, the insulating layer 40 will be as close as possible to the interface between the electrode and the ceramic body 10. The insulating layer 40 covers the top surface 11 of the ceramic body 10 and extends along the x-axis to the first sidewall 23 of the inner electrode layer 20. The outer electrode layer 30 partially covers the insulating layer 40 and the first sidewall 23 of the inner electrode layer 20, and continues to extend to the top surface 21 of the inner electrode, the second sidewall 24 and the second end face 14 of the ceramic body 10. In addition, as mentioned above, the outer electrode layer 30 covers the entire inner electrode layer 20, that is, the outer electrode layer 30 also covers the inner electrode layer 20 in the yz plane (e.g., Figure 2(As shown). Thus, only the insulating layer 40 and the outer electrode layer 30 of the ceramic thermistor 100 are exposed to the external environment. It should be understood that the same configuration as described above can also be present on the bottom surface 12 of the ceramic body 10.

[0071] Please continue to refer to Figures 4 to 5D Various views of a second embodiment of the ceramic thermistor 200 of the present invention are shown. The main difference between the ceramic thermistor 200 and the ceramic thermistor 100 lies in the area covered by the outer electrode layer 30. In the ceramic thermistor 200, the outer electrode layer 30 does not cover the second sidewall 24 of the inner electrode layer 20, nor does it cover the first end face 13 and the second end face 14. More specifically, the ceramic thermistor 200 includes a ceramic body 10, an inner electrode layer 20, an outer electrode layer 30, and an insulating layer 40. The ceramic body 10 is a hexahedron with a positive temperature coefficient (i.e., a hexahedron including a top surface 11, a bottom surface 12, a first end face 13, a second end face 14, a first side face 15, and a second side face 16). Figure 4 In this process, the outer electrode layer 30, located at both ends of the top surface 11 and the bottom surface 12 of the ceramic body 10, does not cover the first side surface 15 and the second side surface 16, nor does it extend towards the second sidewall 24 of the inner electrode layer 20, thus not covering the first end surface 13 and the second end surface 14. Similarly, the remaining portions of the ceramic body 10 exposed to the external environment are covered by the insulating layer 40. Thus, a ceramic thermistor 200 is formed, with two sides covered by the outer electrode layer 30 at each end.

[0072] Please continue to refer to Figure 5A and Figure 5D . Figure 5A for Figure 4 A cross-sectional view of the ceramic thermistor 200 along line segment AA. Figure 5D show Figure 5AA partially enlarged view of the ceramic thermistor 200 within the dashed box. The inner electrode layer 20 has an inner electrode top surface 21, an inner electrode bottom surface 22, a first sidewall 23, and a second sidewall 24. The inner electrode top surface 21 is parallel to the top surface 11 of the ceramic body 10 and is disposed opposite to the inner electrode bottom surface 22. The first sidewall 23 and the second sidewall 24 are disposed opposite to each other and connect the inner electrode top surface 21 and the inner electrode bottom surface 22. The inner electrode bottom surface 22 is substantially coplanar with the top surface 11 of the ceramic body 10. That is, the first sidewall 23 extends vertically from the inner electrode top surface 21 to the top surface 11, and the second sidewall 24 also extends vertically from the inner electrode top surface 21 to the top surface 11. It should also be noted that the second sidewall 24 is coplanar with the second end surface 14, so that the second sidewall 24 of the inner electrode layer 20 and the second end surface 14 of the ceramic body 10 are flush when viewed along the y-axis, thus the second sidewall 24 is exposed to the external environment. Of course, in some embodiments, the second sidewall 24 may also be designed to be non-coplanar with the second end face 14 (not shown), so that the second sidewall 24 of the inner electrode layer 20 and the second end face 14 of the ceramic body 10 have a step difference when viewed along the y-axis; in this way, the outer electrode layer 30 can completely cover the second sidewall 24 during the process. Similarly, to avoid the influence of plating, moisture or other external factors, the insulating layer 40 will be as close as possible to the interface between the electrode and the ceramic body 10. The insulating layer 40 covers the top surface 11 of the ceramic body 10 and extends along the x-axis to the first sidewall 23 of the inner electrode layer 20. The outer electrode layer 30 partially covers the insulating layer 40 and the first sidewall 23 of the inner electrode layer 20, and continues to extend to the top surface 21 of the inner electrode, ending at the junction of the top surface 21 of the inner electrode and the second sidewall 24. In this way, the outer electrode layer 30 does not extend to the second end face 14. In addition, the outer electrode layer 30 also covers the inner electrode layer 20 in the yz plane (e.g., Figure 4 (As shown). Thus, only the second sidewall 24 of the inner electrode layer 20, the insulating layer 40, and the outer electrode layer 30 of the ceramic thermistor 200 are exposed to the external environment. It is also understood that components identical to those described above use the same component symbols and can have the same functions and configurations as described above. To avoid redundancy, the remaining components will not be described again here.

[0073] The configuration relationship between the layers can also be adjusted as needed, such as... Figures 6A to 7B Various embodiments are shown.

[0074] Figure 6A and Figure 6B Cross-sectional views of embodiments of ceramic thermistor 100 and ceramic thermistor 200 are shown respectively. Figure 3A compared to, Figure 6A The insulating layer 40 covers the inner wall of the outer electrode layer 30. Similarly, with Figure 5A compared to, Figure 6BAn insulating layer 40 covers the inner wall of the outer electrode layer 30. Specifically, the outer electrode layer 30 covers the top surface 21 of the inner electrode of the inner electrode layer 20, continues to completely cover the first sidewall 23 of the inner electrode layer 20 along the y-axis, and connects to the top surface 11 of the ceramic body 10. The insulating layer 40 extends along the z-axis on the top surface 11 to the outer electrode layer 30, and further extends parallel to the first sidewall 23 of the inner electrode layer 20 along the y-axis and covers the outer electrode layer 30. Thus, the insulating layer 40 is formed on the inner walls of opposite sides of the outer electrode layer 30, which can effectively prevent the generation of electric arc between the two electrodes. It is also understood that the same components as those described above use the same component symbols and can have the same functions and configurations as described above. To avoid redundancy, the remaining components will not be described again here.

[0075] Figure 7A and Figure 7B Cross-sectional views of embodiments of ceramic thermistor 100 and ceramic thermistor 200 are shown respectively. Figure 3A compared to, Figure 7A The insulating layer 40 further covers the inner wall and part of the top surface of the inner electrode layer 20. Similarly, with... Figure 5A compared to, Figure 7B The insulating layer 40 further covers the inner wall and part of the top surface of the inner electrode layer 20. Specifically, the insulating layer 40 extends along the z-axis on the top surface 11 to the first sidewall 23 of the inner electrode layer 20, continues to extend along the y-axis and completely covers the first sidewall 23, and finally extends along the z-axis to the top surface 21 of the inner electrode. In this way, the outer electrode layer 30 and the first sidewall 23 of the inner electrode layer 20 are not in direct contact, and the insulating layer 40 is in between. The insulating layer 40 penetrates deeper into the interface between the inner and outer electrodes, providing more comprehensive protection. It is also understood that the same components as those described above use the same component symbols and can have the same functions and configurations as described above. To avoid redundancy, the remaining components will not be described again here.

[0076] Furthermore, the present invention further improves the material composition of the ceramic body 10 in conjunction with the aforementioned structural design.

[0077] Table 1

[0078]

[0079] 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 25Rs 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 .

[0080] The preparation method of ceramic body 10 is described below.

[0081] 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 granulated to form numerous ceramic particles. These ceramic particles are then hot-pressed into plate-shaped ceramic blanks, which are then sintered in a sintering furnace 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%. The ceramic body 10 was then subjected to elemental analysis and electrical property testing, and the results are shown in Table 1.

[0082] As shown in Table 1, the ceramic body 10 comprises a first component and a second component.

[0083] 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 fine-graining control agent 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.

[0084] 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 / R25 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 (R0) is also higher. 125 / R 25 The value is also relatively low.

[0085] 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 second 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 second 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.

[0086] 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 resistivity jump rate (R). 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.

[0087] 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.

[0088] 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%.

[0089] In the aforementioned sintering process, this invention further includes testing the adjustment of the oxygen content in the sintering atmosphere. Please refer to Table 2 and... Figure 8 .

[0090] Table 2

[0091]

[0092] like Figure 8 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.

[0093] 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 11 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.

[0094] 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 later part of the cooling stage (T4-T5) maintained 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) both 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 (R0) 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.

[0095] Table 3

[0096]

[0097] In Table 3, the present invention tests the aforementioned ceramic body 11 with different structural designs. The number of external electrode coverage areas refers to the number of coverage areas of the external electrode layers 3 and 30 at one end of the element. For example, Figure 2 The outer electrode layer 30 covers the top surface 11, the first end surface 13 and the bottom surface 12, so the number of outer electrode coverage surfaces is 3; Figure 4 The outer electrode layer 30 covers the top surface 11 and the bottom surface 12, therefore the number of outer electrode coverage surfaces is 2; and Figure 1A The outer electrode layer 3 covers all surfaces at one end, so the number of outer electrode coverage surfaces is 5.

[0098] The width of the inner electrode refers to the width of the inner electrode layer at one end when viewed in a cross-sectional view, such as... Figure 3A and Figure 5A The width W is shown. The inner electrode spacing is the aforementioned spacing G.

[0099] The ceramic bodies of groups E20, 21, 13, 22, 23, and 14 are all the same as those in the aforementioned embodiment E12.

[0100] Please refer to Examples E20, E21, and Comparative Example C13. The inner electrode spacing in all groups was 0.45 mm, and the inner electrode width ranged from 0.148 mm to 0.153 mm. Results showed that, compared to conventional structural designs, the ceramic thermistor 100 of the first embodiment of the present invention (i.e., Example E21) exhibited a lower resistance value, while the ceramic thermistor 200 of the second embodiment of the present invention (i.e., Example E20) exhibited a better resistance jump rate (R0). 125 / R 25 ).

[0101] Please refer to Examples E22, E23, and Comparative Example C14. The inner electrode spacing in all groups was 0.4 mm, and the inner electrode width ranged from 0.198 mm to 0.205 mm. Similarly, the results show that, compared to conventional structural designs, the ceramic thermistor 100 of the first embodiment of the present invention (i.e., Example E23) can have a lower resistance value, while the ceramic thermistor 200 of the second embodiment of the present invention (i.e., Example E22) can have a better resistance jump rate (R0). 125 / R 25 ).

[0102] The ceramic bodies of groups E24, 25, 15, 26, 27, and 16 are all the same as those in the aforementioned embodiment E17.

[0103] Please refer to Examples E24, E25, and Comparative Example C15. The inner electrode spacing in all groups was 0.45 mm, and the inner electrode width ranged from 0.146 mm to 0.155 mm. Results showed that, compared to conventional structural designs, the ceramic thermistor 100 of the first embodiment of the present invention (i.e., Example E25) exhibited a lower resistance value, while the ceramic thermistor 200 of the second embodiment of the present invention (i.e., Example E24) exhibited a better resistance jump rate (R0). 125 / R 25 ).

[0104] Please refer to Examples E26, E27, and Comparative Example C16. The inner electrode spacing in all groups was 0.4 mm, and the inner electrode width ranged from 0.197 mm to 0.208 mm. Similarly, the results show that, compared to conventional structural designs, the ceramic thermistor 100 of the first embodiment of the present invention (i.e., Example E27) can have a lower resistance value, while the ceramic thermistor 200 of the second embodiment of the present invention (i.e., Example E26) can have a better resistance jump rate (R0). 125 / R 25 ).

[0105] In summary, the ceramic thermistor of the present invention can be designed to have low volume resistivity, suitable Curie point, and good resistance jump rate. Furthermore, the electrical properties can be further improved by adjusting the material composition of the ceramic body.

[0106] 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 based on the teachings and disclosures of this invention without departing from the spirit of this invention. 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 a positive temperature coefficient characteristic, and comprising a top surface, a bottom surface, a first end surface and a second end surface, wherein the top surface and the bottom surface are disposed opposite to each other, and the first end surface and the second end surface are disposed opposite to each other and connected to the top surface and the bottom surface; An inner electrode layer is disposed at both ends of the top surface, and the inner electrode layers at both ends are separated by a distance; and An outer electrode layer covers the inner electrode layer.

2. The ceramic thermistor according to claim 1, wherein the ceramic body further comprises a first side surface and a second side surface opposite to the first side surface, connecting the top surface, the bottom surface, the first end surface and the second end surface, thereby forming a hexahedron, wherein the outer electrode layer extends and covers the first end surface and the second end surface, but does not cover the first side surface and the second side surface.

3. The ceramic thermistor according to claim 2 further comprises an insulating layer covering the top surface of the ceramic body, wherein the insulating layer is disposed within the spacing of the inner electrode layers at both ends.

4. The ceramic thermistor according to claim 3, wherein the inner electrode layer has an inner electrode top surface and a first sidewall, wherein: The top surface of the inner electrode is parallel to the top surface of the ceramic body, and the first sidewall extends perpendicularly from the top surface of the inner electrode to the top surface; and The insulating layer extends to the first sidewall, thereby the outer electrode layer partially covers the insulating layer and the first sidewall.

5. The ceramic thermistor according to claim 4, wherein the insulating layer completely covers the first sidewall of the inner electrode layer and extends further to the top surface of the inner electrode, thereby the outer electrode layer partially covers the insulating layer and the top surface of the inner electrode.

6. The ceramic thermistor according to claim 3, wherein the inner electrode layer has an inner electrode top surface and a first sidewall, wherein: The top surface of the inner electrode is parallel to the top surface of the ceramic body, and the first sidewall extends vertically from the top surface of the inner electrode to the top surface. The outer electrode layer covers the first sidewall of the inner electrode layer and the top surface of the inner electrode; and The insulating layer extends to the outer electrode layer and further extends parallel to the first sidewall and covers the outer electrode layer.

7. The ceramic thermistor according to claim 3, wherein the insulating layer further covers the bottom surface, the first side surface and the second side surface of the ceramic body, such that only the insulating layer and the outer electrode layer of the ceramic thermistor are exposed to the external environment.

8. The ceramic thermistor according to claim 1, wherein the spacing is 0.4 mm to 0.45 mm.

9. The ceramic thermistor according to claim 1, wherein the inner electrode layer has a width extending toward the first end face and the second end face, and the width is 0.15 mm to 0.21 mm.

10. The ceramic thermistor of claim 1, wherein the material of the inner electrode layer does not contain titanium.

11. The ceramic thermistor according to claim 10, wherein the material of the inner electrode layer is selected from the group consisting of nickel, chromium, nickel-chromium alloys, nickel-copper alloys, silver, aluminum, and combinations thereof.

12. The ceramic thermistor 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 10 Ω·cm.

13. The ceramic thermistor element according to claim 12, 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%, thus giving the ceramic body a Curie temperature of 85°C to 91°C.

14. The ceramic thermistor element according to claim 12, 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%.

15. The ceramic thermistor element according to claim 14, 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.

16. A ceramic thermistor, comprising: A ceramic body having a positive temperature coefficient characteristic, and comprising a top surface, a bottom surface, a first end surface and a second end surface, wherein the top surface and the bottom surface are disposed opposite to each other, and the first end surface and the second end surface are disposed opposite to each other and connected to the top surface and the bottom surface; An inner electrode layer is disposed at both ends of the top surface, and the inner electrode layers at both ends are separated by a distance; and An outer electrode layer covers the inner electrode layer and the top surface of the ceramic body, and does not extend to the first end face and the second end face.

17. The ceramic thermistor of claim 16, wherein the ceramic body further comprises a first side surface and a second side surface opposite to the first side surface, connecting the top surface, the bottom surface, the first end surface and the second end surface, thereby forming a hexahedron, wherein the outer electrode layer does not cover the first side surface and the second side surface.

18. The ceramic thermistor of claim 17 further comprises an insulating layer covering the top surface of the ceramic body, wherein the insulating layer is disposed within the spacing of the inner electrode layers at both ends.

19. The ceramic thermistor according to claim 18, wherein the inner electrode layer has an inner electrode top surface and a first sidewall, wherein: The top surface of the inner electrode is parallel to the top surface of the ceramic body, and the first sidewall extends perpendicularly from the top surface of the inner electrode to the top surface; and The insulating layer extends to the first sidewall, thereby the outer electrode layer partially covers the insulating layer and the first sidewall.

20. The ceramic thermistor of claim 19, wherein the insulating layer completely covers the first sidewall of the inner electrode layer and extends further to the top surface of the inner electrode, thereby the outer electrode layer partially covers the insulating layer and the top surface of the inner electrode.

21. The ceramic thermistor according to claim 18, wherein the inner electrode layer has an inner electrode top surface and a first sidewall, wherein: The top surface of the inner electrode is parallel to the top surface of the ceramic body, and the first sidewall extends vertically from the top surface of the inner electrode to the top surface. The outer electrode layer covers the first sidewall of the inner electrode layer and the top surface of the inner electrode; and The insulating layer extends to the outer electrode layer and further extends parallel to the first sidewall and covers the outer electrode layer.

22. The ceramic thermistor of claim 18, wherein the insulating layer further covers the bottom surface, the first side surface, the second side surface, the first end surface, and the second end surface of the ceramic body.

23. The ceramic thermistor according to claim 16, wherein the spacing is from 0.4 mm to 0.45 mm.

24. The ceramic thermistor of claim 16, wherein the inner electrode layer has a width extending toward the first end face and the second end face, and the width is from 0.15 mm to 0.21 mm.

25. The ceramic thermistor of claim 16, wherein the material of the inner electrode layer does not contain titanium.

26. The ceramic thermistor of claim 25, wherein the material of the inner electrode layer is selected from the group consisting of nickel, chromium, nickel-chromium alloys, nickel-copper alloys, silver, aluminum, and combinations thereof.

27. The ceramic thermistor element according to claim 16, 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 10 Ω·cm.

28. The ceramic thermistor element according to claim 27, 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%, thus giving the ceramic body a Curie temperature of 85°C to 91°C.

29. The ceramic thermistor element according to claim 27, 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%.

30. The ceramic thermistor element according to claim 29, 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.

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