Circuit protection device

Abstract

A circuit protection device comprises a PTC (Positive Temperature Coefficient) element, an insulating unit and a device electrode unit, the PTC element includes a PTC layer, a first PTC electrode, and a second PTC electrode. The PTC layer is provided with an upper surface, a lower surface and two opposite side walls, and the two side walls are connected to the upper surface and the lower surface. The first PTC electrode is formed on the upper surface of the PTC layer; the second PTC electrode is formed on a lower surface of the PTC layer. The insulation unit is arranged on the PTC element. The device electrode unit is formed on the insulating unit and includes a first device electrode and a second device electrode. The first device electrode is electrically connected to the first PTC electrode and is spaced from one of the two side walls; the second device electrode is electrically connected to the second PTC electrode. The circuit protection device is excellent in stability and durability.

Description

Technical Field

[0001] This invention relates to a circuit protection device, and more particularly to a positive temperature coefficient (PTC) circuit protection device. Background Technology

[0002] Positive temperature coefficient (PTC) elements exhibit the PTC effect, enabling their use as circuit protection devices (e.g., resettable fuses). The PTC element may include a PTC polymer unit and first and second electrodes formed on two opposite surfaces of the PTC polymer unit. The PTC polymer unit includes a polymer substrate containing crystalline and amorphous regions, and particulate conductive filler. The particulate conductive filler is dispersed in the amorphous regions of the polymer substrate, forming a continuous conductive path for electrically connecting the first and second electrodes. The PTC effect refers to the phenomenon that when the temperature of the polymer substrate in the crystalline region is raised to its melting point, the crystals in the crystalline region begin to melt, thereby creating new amorphous regions. When the number of new amorphous regions increases to the point of merging with the original amorphous regions, the conductive path of the particulate conductive filler gradually becomes an open circuit, and the resistance of the PTC polymer unit increases sharply, causing a loss of electrical conductivity between the first and second electrodes.

[0003] See Figure 1 A conventional surface-mounted circuit protection device 1 includes a PTC unit 14, a first insulating layer 15, a second insulating layer 16, a first electrode 17, and a second electrode 18. The PTC unit 14 includes a first conductive member 12, a second conductive member 13, and a polymer layer 11 stacked between the first conductive member 12 and the second conductive member 13. The polymer layer 11 exhibits PTC characteristics and includes a polymer substrate and particulate conductive fillers dispersed in the polymer substrate. The first insulating layer 15 is disposed on the first conductive member 12, and the second insulating layer 16 is disposed on the second conductive member 13. The first electrode 17 is electrically connected to the first conductive member 12 and disposed on the first insulating layer 15, and further extends toward the second insulating layer 16. Similarly, the second electrode 18 is electrically connected to the second conductive member 13 and disposed on the second insulating layer 16, and further extends toward the first insulating layer 15.

[0004] Circuit protection devices are fail-safe devices designed to protect people or equipment in the event of an electrical fault. Therefore, there is a strong demand in many related industries for improving the stability and performance of circuit protection devices. Summary of the Invention

[0005] The purpose of this invention is to provide a circuit protection device that can overcome at least one of the disadvantages of the aforementioned background technology.

[0006] The circuit protection device of the present invention includes a PTC element, an insulating unit, and a device electrode unit. The PTC element includes a PTC layer, a first PTC electrode, and a second PTC electrode. The PTC layer has an upper surface, a lower surface, and two opposite sidewalls interconnected on the upper and lower surfaces. The first PTC electrode is formed on the upper surface of the PTC layer; the second PTC electrode is formed on the lower surface of the PTC layer. The insulating unit is disposed on the PTC element. The device electrode unit is formed on the insulating unit and includes a first device electrode and a second device electrode. The first device electrode is electrically connected to the first PTC electrode and spaced apart from one of the two sidewalls; the second device electrode is electrically connected to the second PTC electrode.

[0007] The circuit protection device of the present invention has a first device electrode disposed at a distance from one of the two sidewalls via the insulating unit.

[0008] The circuit protection device of the present invention has a second device electrode spaced apart from the other of the two sidewalls.

[0009] The circuit protection device of the present invention has a second device electrode disposed at a distance from one of the two sidewalls via the insulating unit.

[0010] The circuit protection device of the present invention includes an insulating unit comprising a first insulating layer and a second insulating layer; a first device electrode is spaced apart from one of the two sidewalls through the second insulating layer; and a second device electrode is spaced apart from the other of the two sidewalls through the first insulating layer.

[0011] The circuit protection device of the present invention has a first insulating layer having a first body portion and a first extension portion, the first body portion covering the first PTC electrode, and the first extension portion being connected to the first body portion and extending from the first body portion toward the second insulating layer to cover one of the two sidewalls.

[0012] The circuit protection device of the present invention has a second insulating layer having a second body portion and a second extension portion. The second body portion covers the second PTC electrode, and the second extension portion is connected to the second body portion and extends from the second body portion toward the first insulating layer to cover one of the two sidewalls.

[0013] The circuit protection device of the present invention has a first body portion having a first outward-facing surface facing away from the PTC element, and a second body portion having a second outward-facing surface facing away from the PTC element; a first PTC electrode having a first electrode surface facing the first insulating layer, and a second PTC electrode having a second electrode surface facing the second insulating layer; and the area of ​​the first electrode surface is smaller than the area of ​​the first outward-facing surface, and the area of ​​the second electrode surface is smaller than the area of ​​the second outward-facing surface.

[0014] In the circuit protection device of the present invention, the area of ​​the first electrode surface is 50% to 95% of the area of ​​the first outward-facing surface; and the area of ​​the second electrode surface is 50% to 95% of the area of ​​the second outward-facing surface.

[0015] In the circuit protection device of the present invention, the area of ​​the first electrode surface is 87% to 94% of the area of ​​the first outward-facing surface; and the area of ​​the second electrode surface is 87% to 94% of the area of ​​the second outward-facing surface.

[0016] In the circuit protection device of the present invention, the projection of the PTC layer on a virtual plane covering its upper surface falls within the range of the projection of the insulating unit on the virtual plane.

[0017] The circuit protection device of the present invention further includes a first conductive member and a second conductive member. The first conductive member is disposed on the first electrode surface of the first PTC electrode, and the first electrode surface is electrically interconnected with the first PTC electrode and the first device electrode. The second conductive member is disposed on the second electrode surface of the second PTC electrode, and the second electrode surface is electrically interconnected with the second PTC electrode and the second device electrode.

[0018] The circuit protection device of the present invention includes an insulating unit that encloses the PTC element, such that the PTC element is spaced apart from the first device electrode and the second device electrode through the insulating unit.

[0019] The circuit protection device of the present invention has a PTC element having at least one hole.

[0020] The circuit protection device of the present invention has at least one hole extending through at least one of the upper and lower surfaces of the PTC layer.

[0021] The circuit protection device of the present invention further includes at least one hole extending through at least one of the first PTC electrode and the second PTC electrode of the PTC element.

[0022] The circuit protection device of the present invention includes a PTC layer comprising a polymer substrate and particulate conductive filler dispersed in the polymer substrate, wherein the polymer substrate comprises an ungrafted olefin polymer.

[0023] The circuit protection device of the present invention further includes an olefin polymer grafted with carboxylic anhydride in the polymer substrate.

[0024] In the circuit protection device of the present invention, the ungrafted olefin polymer is high-density polyethylene.

[0025] The circuit protection device of the present invention uses a particulate conductive filler selected from carbon black powder, metal powder, conductive ceramic powder, or a combination thereof.

[0026] The beneficial effects of this invention are that the circuit protection device has excellent stability and durability. Attached Figure Description

[0027] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a cross-sectional schematic diagram of an existing surface-mount circuit protection device;

[0029] Figure 2 This is an exploded perspective view of an embodiment of the circuit protection device of the present invention;

[0030] Figure 3 This is a cross-sectional schematic diagram of this embodiment;

[0031] Figure 4 This is a three-dimensional exploded view of the variation state of this embodiment;

[0032] Figure 5 This is a cross-sectional schematic diagram of another embodiment of the circuit protection device of the present invention; and

[0033] Figure 6 This is a three-dimensional schematic diagram of a first comparative example of an existing surface-mount circuit protection device. Detailed Implementation

[0034] Before the invention is described in detail, it should be noted that similar elements are represented by the same numbers in the following description.

[0035] Furthermore, the directional terms (e.g., up, down, above, below) used in the specification and claims of this invention are merely intended to help describe the relative positions between the elements of the invention, rather than to limit the actual position of each element when the invention is actually performed.

[0036] See Figure 2 and Figure 3An embodiment of the circuit protection device of the present invention includes a PTC element 2, a conductive member 3, an insulating unit 4, and a device electrode unit 5. The conductive member 3 includes a first conductive member 31 and a second conductive member 32. The device electrode unit 5 is formed on the insulating unit 4 and includes a first device electrode 51 and a second device electrode 52.

[0037] The PTC element 2 includes a PTC layer 21, a first PTC electrode 22, and a second PTC electrode 23. The PTC layer 21 has an upper surface, a lower surface, and two opposite sidewalls 211, which are interconnected on the upper and lower surfaces. In this embodiment, the first device electrode 51 is electrically connected to the first PTC electrode 22 and is spaced apart from one of the two sidewalls 211; the second device electrode 52 is electrically connected to the second PTC electrode 23 and is spaced apart from the other of the two sidewalls 211. In other embodiments, only one of the first device electrode 51 and the second device electrode 52 is spaced apart from one of the two sidewalls 211.

[0038] The PTC layer 21 includes a polymer substrate and particulate conductive fillers dispersed in the polymer substrate. The polymer substrate may be made from a polymer composition containing an ungrafted olefin polymer (e.g., high-density polyethylene (HDPE)). In some embodiments of the invention, the polymer composition further includes a grafted olefin polymer. In some embodiments of the invention, the grafted olefin polymer includes a carboxylic anhydride-grafted olefin polymer. The carboxylic anhydride-grafted olefin polymer may be carboxylic anhydride-grafted high-density polyethylene. In this embodiment, the carboxylic anhydride-grafted olefin polymer is maleic anhydride-grafted HDPE.

[0039] In some specific embodiments of the present invention, the particulate conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder, or a combination thereof.

[0040] Examples of such particulate conductive fillers include titanium carbide, zirconium carbide, vanadium carbide, molybdenum carbide, tungsten carbide, titanium nitride, zirconium nitride, vanadium nitride, niobium nitride, tantalum nitride, chromium nitride, titanium disilicide, niobium disilicide, gold, silver, copper, aluminum, nickel, nickel metallized glass beads, nickel metallized graphite, Ti-Ta solid solution, W-Ti-Ta-Cr solid solution, W-Ta solid solution, W-Ti-Ta-Nb solid solution, W-Ti-Ta solid solution, W-Ti solid solution, Ta-Nb solid solution, or combinations thereof.

[0041] In some specific embodiments of the present invention, the polymer substrate may account for 5 wt% to 50 wt% of the PTC layer 21, and the particulate conductive filler may account for 50 wt% to 95 wt% of the PTC layer 21.

[0042] Each first PTC electrode 22 and each second PTC electrode 23 may be made of a conductive material, such as a metal. The first PTC electrode 22 is formed on the upper surface of the PTC layer 21 and has a first electrode surface A1; the second PTC electrode 23 is formed on the lower surface of the PTC layer 21 and has a second electrode surface A2.

[0043] The first conductive member 31 and the second conductive member 32 may be made of a conductive material, such as a metal. The first conductive member 31 is electrically interconnected to the first PTC electrode 22 and is disposed on the first PTC electrode 22 opposite to the PTC layer 21. The second conductive member 32 is electrically interconnected to the second PTC electrode 23 and is disposed on the second PTC electrode 23 opposite to the PTC layer 21. More specifically, the first conductive member 31 is disposed on the first electrode surface A1 of the first PTC electrode 22, and the second conductive member 32 is disposed on the second electrode surface A2 of the second PTC electrode 23.

[0044] See Figure 3 In this embodiment, the insulating unit 4 is disposed on the PTC element 2 and covers the two sidewalls 211 of the PTC layer 21, that is, the insulating unit 4 is disposed between the two sidewalls 211 and the device electrode unit 5. In other embodiments, the insulating unit 4 covers only one of the two sidewalls 211.

[0045] See Figure 4 Alternatively, the insulating unit 4 can completely enclose the PTC element 2, so that the PTC element 2 is spaced apart from the first device electrode 51 and the second device electrode 52 through the insulating unit 4. In this embodiment, the first conductive member 31 is electrically interconnected with the first PTC electrode 22 and the first device electrode 51, and the second conductive member 32 is electrically interconnected with the second PTC electrode 23 and the second device electrode 52.

[0046] In this embodiment, the first device electrode 51 is spaced apart from one of the two sidewalls 211 via the insulating unit 4, and the second device electrode 52 is spaced apart from the other of the two sidewalls 211 via the insulating unit 4. More specifically, the insulating unit 4 includes a first insulating layer 41 and a second insulating layer 42. The first device electrode 51 is spaced apart from one of the two sidewalls via the second insulating layer 42, and the second device electrode 52 is spaced apart from the other of the two sidewalls 211 via the first insulating layer 41.

[0047] In this embodiment, the first electrode surface A1 of the first PTC electrode 22 faces the first insulating layer 41, and the second electrode surface A2 of the second PTC electrode 23 faces the second insulating layer 42. The first insulating layer 41 has a first body portion 411 and a first extension portion 412. The first body portion 411 has a first outward-facing surface B1 facing away from the PTC element 2 and covers the PTC layer 21, the first PTC electrode 22, and the first conductive member 31. The first extension portion 412 is connected to the first body portion 411 and extends from the first body portion 411 toward the second insulating layer 42 to cover one of the two sidewalls 211. The second insulating layer 42 has a second body portion 421 and a second extension portion 422. The second body portion 421 has a second outward-facing surface B2 facing away from the PTC element 2 and covers the PTC layer 21, the second PTC electrode 23, and the second conductive member 32. The second extension 422 is connected to the second body portion 421 and extends from the second body portion 421 toward the first insulating layer 41 to cover one of the two sidewalls 211. The first conductive member 31 extends outward from the first electrode surface A1 to contact the first device electrode 51, and the second conductive member 32 extends outward from the second electrode surface A2 to contact the second device electrode 52.

[0048] In this embodiment, the first device electrode 51 is disposed on a portion of the first outer surface B1 and a portion of the second outer surface B2, and extends to contact the end of the first conductive member 31 and the second extension 422; the second device electrode 52 is disposed on a portion of the second outer surface B2 and a portion of the first outer surface B1, and extends to contact the end of the second conductive member 32 and the first extension 412.

[0049] In this embodiment, one of the two sidewalls 211 is adjacent to the second insulating layer 42, and the other of the two sidewalls 211 is adjacent to the first insulating layer 41.

[0050] In some specific embodiments of the present invention, the size of the PTC element 2 is at least 0.2 mm smaller than the size of the circuit protection device.

[0051] In some specific embodiments of the present invention, the area of ​​the first electrode surface A1 is smaller than the area of ​​the first outward-facing surface B1, and the area of ​​the second electrode surface A2 is smaller than the area of ​​the second outward-facing surface B2.

[0052] See Figure 2 In some specific embodiments of the present invention, the projection of the PTC layer 21 onto a virtual plane covering its upper surface falls within the range of the projection of the insulating unit 4 onto the virtual plane.

[0053] In some specific embodiments of the present invention, the area of ​​the first electrode surface A1 is 50% to 95% of the area of ​​the first outward-facing surface B1, and the area of ​​the second electrode surface A2 is 50% to 95% of the area of ​​the second outward-facing surface B2.

[0054] In some specific embodiments of the present invention, the area of ​​the first electrode surface A1 is 87% to 94% of the area of ​​the first outward-facing surface B1, and the area of ​​the second electrode surface A2 is 87% to 94% of the area of ​​the second outward-facing surface B2.

[0055] See Figure 5 In another embodiment of the invention, the PTC element 2 has at least one hole 24. The at least one hole 24 extends through at least one of the upper and lower surfaces of the PTC layer 21. In some specific embodiments of the invention, the at least one hole 24 also extends through at least one of the first PTC electrode 22 and the second PTC electrode 23 of the PTC element 2. The number of the at least one hole 24 may be, but is not limited to, one, two, or more than three.

[0056] The present invention will be further described with reference to the following embodiments, but it should be understood that the embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0057] Example

[0058] <Example 1 (E1)>

[0059] First, 10.25g of HDPE (purchased from Formosa Plastics Industrial Co., Ltd., product model: HDPE9002) was used as the ungrafted olefin polymer, 10.25g of maleic anhydride-grafted HDPE (purchased from DuPont, product model: MB100D) was used as the carboxylic anhydride-grafted olefin polymer, and 29.5g of carbon black powder (purchased from Columbia Chemicals, product model: Raven 430UB) was used as the granular conductive filler. The above ingredients were mixed in a mixer (Brabender brand) at 200°C and 30 rpm for 10 minutes to obtain the mixture.

[0060] The above-mentioned mixture of ingredients was placed in a mold and hot-pressed at a temperature of 200°C and a pressure of 80 kg / cm². 2 The PTC layer 21 with a thickness of 0.35 mm was obtained by hot pressing for 4 minutes under the following conditions. This PTC layer 21 was then sandwiched between two copper foils (serving as the first PTC electrode 22 and the second PTC electrode 23) and heated at 200°C and 80 kg / cm². 2The PTC element body was hot-pressed for 4 minutes to obtain a thickness of 0.42 mm. The PTC element body was then cut into multiple semi-finished elements with a size of 5.0 mm × 7.2 mm, and subsequently irradiated with Co-60 gamma rays at a total radiation dose of 150 kGy.

[0061] Next, two copper sheets (as the first conductive component 31 and the second conductive component 32) are formed on the two copper foils of the above-mentioned semi-finished component using a printed circuit board (PCB) process.

[0062] Next, epoxy resin glass fiber layers (serving as the first insulating layer 41 and the second insulating layer 42, respectively) are formed on the first conductive member 31 and the second conductive member 32, and then subjected to 150°C and 80 kg / cm² temperature. 2 The product is then hot-pressed for 40 minutes to form an intermediate product with dimensions of 5.2mm × 7.4mm.

[0063] Next, the first device electrode 51 and the second device electrode 52 are electroplated on the aforementioned intermediate product to obtain the circuit protection device of E1 (such as...). Figure 2 and Figure 3 (As shown).

[0064] <Example 2 (E2)>

[0065] The process conditions for the circuit protection device of E2 are similar to those of E1. The difference is that the size of the semi-finished component of E2 is 4.8mm×7.0mm (the size of the intermediate product of E2 is 5.2mm×7.4mm).

[0066] <Examples 3 and 4 (E3 and E4)>

[0067] The process conditions for circuit protection devices of E3 and E4 are similar to those of E1 and E2, respectively. The difference lies in the fact that the semi-finished components of E3 and E4 have at least one hole (such as...). Figure 5 (As shown).

[0068] <Comparative Example 1 (CE1)>

[0069] First, 10.25g of HDPE (purchased from Formosa Plastics Industrial Co., Ltd., product model: HDPE9002) was used as the ungrafted olefin polymer, 10.25g of maleic anhydride-grafted HDPE (purchased from DuPont, product model: MB100D) was used as the carboxylic anhydride-grafted olefin polymer, and 29.5g of carbon black powder (purchased from Columbia Chemicals, product model: Raven 430UB) was used as the granular conductive filler. The above ingredients were mixed in a mixer (Brabender brand) at 200°C and 30 rpm for 10 minutes to obtain the mixture.

[0070] The above-mentioned mixture of ingredients was placed in a mold and hot-pressed at a temperature of 200°C and a pressure of 80 kg / cm². 2 The PTC layer 210 with a thickness of 0.35 mm was obtained by hot pressing for 4 minutes under the following conditions. This PTC layer 210 was then sandwiched between two copper foils (serving as PTC electrodes 220 and 230) and heated at 200°C and 80 kg / cm². 2 The PTC element body was hot-pressed for 4 minutes to obtain a thickness of 0.42 mm. The PTC element body was then cut into multiple semi-finished elements with a size of 5.2 mm × 7.4 mm, and subsequently irradiated with Co-60 gamma rays at a total radiation dose of 150 kGy.

[0071] Next, the first device electrode 60 and the second device electrode 61 are formed on the aforementioned semi-finished component by drilling, electroplating, and patterning to obtain the circuit protection device of CE1 (such as...). Figure 6 (As shown).

[0072] <Comparative Example 2 (CE2)>

[0073] The process conditions for the circuit protection device of CE2 are similar to those of CE1, the difference being that the semi-finished components of CE2 have at least one hole.

[0074] Performance testing

[0075] [Resistance Test]

[0076] Ten circuit protection devices from E1-E4 and CE1-CE2 were selected as test samples for resistance testing. The initial resistance (R) of the test samples was measured with an ohmmeter. i The average values ​​of the test results are shown in Table 1.

[0077] Table 1

[0078]

[0079] Breakdown voltage test

[0080] Ten circuit protection devices for E1-E4 and CE1-CE2 were selected as test samples for breakdown voltage testing, with a starting voltage of 8V. dc Maintain the test for 1 minute. If none of the samples burn (indicating a pass), take another 10 samples and increase the voltage by 2V each time. dc The tests were then conducted. The highest voltage (i.e., breakdown voltage) at which all 10 samples of E1-E4 and CE1-CE2 did not burn out after testing was recorded, and the results are shown in Table 1.

[0081] Table 1 shows the breakdown voltage (24-30V) of the test samples E1-E4. dc The breakdown voltage (18V) of the test samples was significantly higher than that of CE1 and CE2. dc and 20V dc This result shows that the spacing between the PTC layer and the first and second device electrodes helps improve the stability of the circuit protection device. Furthermore, compared to test samples E1 and E2, test samples E3 and E4, which have holes, exhibit higher breakdown voltages.

[0082] [Switching cycle test]

[0083] Ten circuit protection devices for E1-E4 and CE1-CE2 were selected as test samples for switching cycle testing at 16V. dc The voltage and current of 10A were applied to the sample for 60 seconds, then cut off for 60 seconds, and this switching cycle was repeated 6000 times. The resistance (R) of each test sample was measured after the test. f1 And calculate the rate of change of resistance (R) f1 / R i (×100%), and the average values ​​of the test results are shown in Table 1.

[0084] Table 1 shows that the average resistance change rate of test samples E1-E4 ranges from 1746% to 2241%, significantly lower than that of test samples CE1 and CE2 (4991% and 4573%, respectively). This result indicates that the spacing between the PTC layer and the first and second device electrodes helps to mitigate the impact of switching cycles, thereby improving the stability and durability of the circuit protection device. Furthermore, compared to test samples E1 and E2, test samples E3 and E4, which have holes, exhibit even lower average resistance change rates.

[0085] [Aging test]

[0086] Ten circuit protection devices for E1-E4 and CE1-CE2 were selected as test samples for aging tests at 16V. dc The voltage and current of 10A were continuously applied to the samples for 1000 hours, and the resistance (R) of each test sample was measured after the test. f2 And calculate the rate of change of resistance (R) f2 / R i The average values ​​of the test results (×100%) are shown in Table 1.

[0087] Table 1 shows that the average resistance change rate of test samples E1-E4 ranged from 183% to 348%, significantly lower than that of test samples CE1 and CE2 (774% and 700%, respectively). This result indicates that the spacing between the PTC layer and the first and second device electrodes helps mitigate the effects of aging, thereby improving the stability and durability of the circuit protection device. Furthermore, compared to test samples E1 and E2, test samples E3 and E4, which have pores, exhibited an even lower average resistance change rate.

[0088] [Environmental test]

[0089] For each of the circuit protection devices E1-E4 and CE1-CE2, 10 units were selected as test samples for environmental testing. The samples were placed in an environment of 85℃ and 85% relative humidity for 1000 hours. The resistance (R) of each test sample after placement was measured using an ohmmeter. f3 And calculate the rate of change of resistance (R) f3 / R i The average values ​​of the test results (×100%) are shown in Table 1.

[0090] Table 1 shows that the average resistance change rate of test samples E1-E4 ranges from 95% to 102%, significantly lower than that of test samples CE1 and CE2 (113% and 118%, respectively). This result indicates that the spacing between the PTC layer and the first and second device electrodes helps to mitigate the influence of the external environment, thereby improving the stability and durability of the circuit protection device. Furthermore, compared to test samples E1 and E2, test samples E3 and E4, which have holes, exhibit even lower average resistance change rates.

[0091] In summary, compared to the existing surface mount circuit protection device 1 where the polymer layer 11 is in direct contact with the first electrode 17 and the second electrode 18, the circuit protection device of the present invention, through the PTC layer 21 being spaced apart from the first device electrode 51 and the second device electrode 52, can more ideally respond to abnormal voltage and current, and is more suitable for high temperature and high humidity environments. It helps to reduce the influence of the external environment and improve the stability and durability of the circuit protection device, thus truly achieving the purpose of the present invention.

[0092] The above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A circuit protection device, characterized in that, It includes: PTC components, including The PTC layer has an upper surface, a lower surface, and two opposite sidewalls that are interconnected between the upper and lower surfaces. The first PTC electrode is formed on the upper surface of the PTC layer, and A second PTC electrode is formed on the lower surface of the PTC layer; An insulating unit is disposed on the PTC element; and Device electrode units are formed on the insulating unit, the device electrode units including A first device electrode is electrically connected to the first PTC electrode and is spaced apart from one of the two sidewalls; and The second device electrode is electrically connected to the second PTC electrode.

2. The circuit protection device according to claim 1, characterized in that: The electrode of the first device is spaced apart from one of the two sidewalls by the insulating unit.

3. The circuit protection device according to claim 1, characterized in that: The electrode of the second device is spaced apart from the other of the two sidewalls.

4. The circuit protection device according to claim 3, characterized in that: The electrode of the second device is spaced apart from one of the two sidewalls by the insulating unit.

5. The circuit protection device according to claim 1, characterized in that: The insulating unit includes a first insulating layer and a second insulating layer; The first device electrode is spaced apart from one of the two sidewalls by the second insulating layer; and The second device electrode is spaced apart from one of the two sidewalls by the first insulating layer.

6. The circuit protection device according to claim 5, characterized in that: The first insulating layer has a first body portion and a first extension portion. The first body portion covers the first PTC electrode, and the first extension portion is connected to the first body portion and extends from the first body portion toward the second insulating layer to cover one of the two sidewalls.

7. The circuit protection device according to claim 6, characterized in that: The second insulating layer has a second body portion and a second extension portion. The second body portion covers the second PTC electrode, and the second extension portion is connected to the second body portion and extends from the second body portion toward the first insulating layer to cover one of the two sidewalls.

8. The circuit protection device according to claim 7, characterized in that: The first body portion has a first surface facing outwards, which is opposite to the PTC element, and the second body portion has a second surface facing outwards, which is opposite to the PTC element. The first PTC electrode has a first electrode surface facing the first insulating layer, and the second PTC electrode has a second electrode surface facing the second insulating layer; and The area of ​​the first electrode surface is smaller than the area of ​​the first facing outward surface, and the area of ​​the second electrode surface is smaller than the area of ​​the second facing outward surface.

9. The circuit protection device according to claim 8, characterized in that: The area of ​​the first electrode surface is 50% to 95% of the area of ​​the first outward-facing surface; and The area of ​​the second electrode surface is 50% to 95% of the area of ​​the second outward-facing surface.

10. The circuit protection device according to claim 9, characterized in that: The area of ​​the first electrode surface is 87% to 94% of the area of ​​the first outward-facing surface; and The area of ​​the second electrode surface is 87% to 94% of the area of ​​the second outward-facing surface.

11. The circuit protection device according to claim 1, characterized in that: The projection of the PTC layer onto the virtual plane covering its upper surface falls within the range of the projection of the insulating unit onto the virtual plane.

12. The circuit protection device according to claim 1, characterized in that: The circuit protection device further includes a first conductive member and a second conductive member. The first conductive member is disposed on the first electrode surface of the first PTC electrode, and the first electrode surface is electrically interconnected with the first PTC electrode and the first device electrode. The second conductive member is disposed on the second electrode surface of the second PTC electrode, and the second electrode surface is electrically interconnected with the second PTC electrode and the second device electrode.

13. The circuit protection device according to claim 1, characterized in that: The insulating unit encloses the PTC element so that the PTC element is spaced apart from the first device electrode and the second device electrode through the insulating unit.

14. The circuit protection device according to claim 1, characterized in that: The PTC element has at least one hole.

15. The circuit protection device according to claim 14, characterized in that: The at least one hole extends through at least one of the upper and lower surfaces of the PTC layer.

16. The circuit protection device according to claim 15, characterized in that: The at least one hole also extends through at least one of the first PTC electrode and the second PTC electrode of the PTC element.

17. The circuit protection device according to claim 1, characterized in that: The PTC layer includes a polymer substrate and particulate conductive fillers dispersed in the polymer substrate, wherein the polymer substrate includes an ungrafted olefin polymer.

18. The circuit protection device according to claim 17, characterized in that: The polymer substrate also includes olefin polymers grafted with carboxylic anhydride.

19. The circuit protection device according to claim 17, characterized in that: The ungrafted olefin polymer is high-density polyethylene.

20. The circuit protection device according to claim 17, characterized in that: The particulate conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder, or a combination thereof.

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