TW202230400A - Composite circuit protection device capable of achieving excellent durability and reliability and protecting diode element from burning in existence of over-current and over-voltage - Google Patents

Abstract

A composite circuit protection device comprises a positive temperature coefficient (PTC) element, a diode element, a first conductive lead, and a second conductive lead. The PTC element includes a PTC layer, a first electrode layer, and a second electrode layer. The PTC layer includes two opposite surfaces. The first electrode layer and the second electrode layer are respectively disposed on two opposite surfaces of the PTC layer. The diode element is connected to the second electrode layer. The first conductive lead is connected to the first electrode layer. The second conductive lead is connected to the diode element. The PTC element has a rated voltage between 50% and 250% of collapse voltage of the diode element measured at 1 mA. The composite circuit protection device of the present invention has excellent durability and the PTC element may protect the diode element from burning in the existence of over-current and over-voltage.

Description

Composite circuit protection device

The present invention relates to a composite circuit protection device, in particular to a composite circuit protection device comprising a positive temperature coefficient (PTC) element and a diode element, and the PTC element has a rated voltage intermediate Breakdown voltage measured at 50% to 250% of the diode element at 1 mA.

US Patent No. 8,508,328 B1 discloses an insertable (insertable) polymer positive temperature coefficient (PPTC) over-current (over-current) protection device, referring to FIG. 1, which includes two electrodes 30, respectively connected to the The first conductive lead 50 and the second conductive lead 60 of the electrodes 30 , and a PTC polymer substrate 20 laminated between the electrodes 30 . The PTC polymer substrate 20 may be formed with a hole 40 having an effective volume to accommodate thermal expansion of the PTC polymer substrate 20 as the temperature increases.

Electrical characteristics such as operating current and high-voltage surge endurability are important factors affecting the occurrence of power surges in PPTC overcurrent protection devices. When the operating current of the PPTC overcurrent protection device is increased by increasing the thickness or area of the PTC polymer substrate 20, it is more susceptible to damage from power surges. On the other hand, when the high voltage tolerance of the PPTC overcurrent protection device is increased by reducing the thickness or area of the PTC polymer substrate 20, it is not necessarily less susceptible to damage from power surges.

Although the combination of the PTC element and the diode can provide over-current and over-voltage protection to the combined circuit protection device, the diode can only withstand power surges for a short period of time ( e.g. 0.001 seconds). That is to say, if the surge time exceeds a cut-off time interval, the diode will be burned or damaged due to overcurrent or overvoltage, resulting in permanent loss of function of the composite circuit protection device.

Therefore, it is an object of the present invention to provide a composite circuit protection device that can overcome at least one of the above-mentioned disadvantages of the prior art.

Therefore, the composite circuit protection device of the present invention includes a positive temperature coefficient (PTC) element, a diode element, a first conductive lead and a second conductive lead. The PTC element includes a PTC layer, a first electrode layer and a second electrode layer, the PTC layer has two opposite surfaces, and the first electrode layer and the second electrode layer are respectively disposed on the two opposite surfaces of the PTC layer. The diode element is connected to the second electrode layer. The first conductive lead is connected to the first electrode layer, and the second conductive lead is connected to the diode element. The PTC element has a voltage rating between 50% and 250% of the breakdown voltage measured at 1 mA for the diode element.

The effect of the present invention is that the composite circuit protection device of the present invention has excellent tolerance and reliability, and in the presence of overcurrent and overvoltage, the PTC element can quickly trip to protect the diode element from burning.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are designated by the same reference numerals.

Referring to FIG. 2 , the first embodiment of the composite circuit protection device of the present invention includes a positive temperature coefficient (PTC) element 2 , a diode element 3 , a first conductive lead 4 and a second conductive lead 5 .

The PTC element 2 includes a PTC layer 21 , a first electrode layer 22 and a second electrode layer 23 , the PTC layer 21 has two opposite surfaces 211 , and the first electrode layer 22 and the second electrode layer 23 are respectively disposed on the PTC layer 21 . Two opposite surfaces 211 of the PTC layer 21 . In some embodiments of the present invention, the first electrode layer 22 and the second electrode layer 23 are connected to the PTC layer 21 through solder. The diode element 3 is connected to the second electrode layer 23 . The first conductive lead 4 is connected to the first electrode layer 22 , and the second conductive lead 5 is connected to the diode element 3 .

According to the present invention, the PTC element 2 has a rated voltage ranging from 50% to 250% of the breakdown voltage of the diode element 3 measured at 1 mA. In some embodiments of the present invention, the PTC element 2 has a rated voltage ranging from 70% to 230% of the breakdown voltage of the diode element 3 measured at 1 mA.

The PTC element 2 is under an overcurrent and a voltage greater than the breakdown voltage of the diode element 3 and trips before the diode element 3 burns out. In other words, in the presence of the overvoltage greater than the breakdown voltage of the diode element 3, the PTC element 2 quickly trips to a high resistance state, so that the overcurrent is restricted from flowing through the diode body element 3, thus protecting the diode element 3 from burning, the composite circuit protection device can thus be reused.

In the present invention, the overvoltage is less than the sum of the rated voltage of the PTC element 2 and the breakdown voltage of the diode element 3 .

In this context, the term "burn-out" refers to the loss of function of the diode element 3, which usually occurs above 180°C.

According to the present invention, the PTC element 2 may be a polymer PTC (PPTC) element, and the PTC layer 21 may be a PTC polymer layer. The PTC polymer layer includes a polymer substrate and a conductive filler dispersed in the polymer substrate. The polymer substrate can be prepared from a polymer composition containing a non-grafted olefin-based polymer. In certain embodiments of the present invention, the non-grafted olefin-based polymer is high density polyethylene (HDPE). In certain embodiments of the present invention, the polymer composition further includes a grafted olefin-based polymer. In certain embodiments of the present invention, the grafted olefin-based polymer is a carboxylic acid anhydride-grafted olefin-based polymer. The conductive filler suitable for the present invention is selected from carbon black powder, metal powder, conductive ceramic powder or a combination of the foregoing, but is not limited thereto. The diode element 3 includes a diode structure 31 , a third electrode layer 32 and a fourth electrode layer 33 . The diode structure 31 has two opposite surfaces 311 . The third electrode layer 32 is disposed on one of the two opposite surfaces 311 of the diode structure 31 and is connected to the second electrode layer 23 of the PTC element 2 through solder. The fourth electrode layer 33 is disposed on the other of the two opposite surfaces 311 of the diode structure 31 . The second conductive lead 5 is connected to one of the third electrode layer 32 and the fourth electrode layer 33 of the diode element 3 .

The PTC element 2 and the diode element 3 can be connected in series or in parallel. The diode element 3 can be a transient voltage suppression (TVS) diode, and the TVS diode includes a silicon wafer with a PN junction.

In this embodiment, the first conductive lead 4 has a connecting portion 41 and a free portion 42 , and the second conductive lead 5 has a connecting portion 51 and a free portion 52 . The connecting portion 41 of the first conductive lead 4 is connected to the outer surface of the first electrode layer 22 by a solder, and the free portion 42 of the first conductive lead 4 extends out of the first electrode layer 22 from the connecting portion 41 A pin hole (not shown) for inserting a circuit board or a circuit device.

In this embodiment, the connecting portion 51 of the second conductive lead 5 is connected to the fourth electrode layer 33 of the diode element 3 by a solder, and the free portion 52 of the second conductive lead 5 is connected from the connecting portion 51 extends out of the fourth electrode layer 33 for insertion into a pin hole of a circuit board or a circuit device (not shown).

According to the present invention, the composite circuit protection device further includes an encapsulation material 7 , which encapsulates the PTC element 2 , the diode element 3 , a part of the first conductive lead 4 and a part of the second conductive lead 5 .

A part of the free part 42 of the first conductive lead 4 and a part of the free part 52 of the second conductive lead 5 are exposed outside the packaging material 7 . In some specific embodiments of the present invention, the encapsulation material 7 is made of epoxy resin.

Referring to FIG. 3 , the modification of the first embodiment of the composite circuit protection device of the present invention is similar to the first embodiment, except that in the modification, a hole 210 is formed in the PTC element 2 . In this embodiment, the hole 210 is formed in the PTC layer 21 . The PTC layer 21 of the PTC element 2 has a peripheral edge that defines the boundary of the PTC layer 21 and is interconnected with the two opposite surfaces 211 of the PTC layer 21 . The hole 210 is spaced from the periphery of the PTC layer 21 and has an effective volume to accommodate the thermal expansion of the PTC layer 21 when the temperature increases, so as to avoid undesired structural deformation of the PTC layer 21 .

In some embodiments of the present invention, the hole 210 penetrates at least one of the two opposite surfaces 211 of the PTC layer 21 . In some embodiments of the present invention, the hole 210 also penetrates at least one of the first electrode layer 22 and the second electrode layer 23 . In this embodiment, the hole 210 penetrates two opposite surfaces 211 of the PTC layer 21 and the first electrode layer 22 and the second electrode layer 23 to form a through hole. In some embodiments of the present invention, the hole 210 extends along a line passing through the geometric center of the PTC layer 21 and across the two opposing surfaces 211 . The hole 210 is defined by a hole-defining wall having a cross-section parallel to the surface 211 of the PTC layer 21 . The cross-section of the hole-defining wall may be circular, square, oval, triangular, cross-shaped, or the like.

Referring to FIG. 4 , the second embodiment of the composite circuit protection device of the present invention is similar to the first embodiment, except that the second embodiment further includes a third conductive lead 6 . In this embodiment, the second conductive lead 5 is connected to the fourth electrode layer 33 of the diode element 3 by a solder, and the third conductive lead 6 is connected to the second electrode by a solder between the layer 23 and the third electrode layer 32 .

The third conductive lead 6 has a connecting portion 61 and a free portion 62 . The connection portion 61 of the third conductive lead 6 is connected to the second electrode layer 23 and the third electrode layer 32 , and the free portion 62 of the third conductive lead 6 extends from the connection portion 61 to the second electrode layer 23 and the third electrode layer 32 . The third electrode layer 32 is used to be inserted into a pin hole of a circuit board or a circuit device (not shown).

In this embodiment, the packaging material 7 encapsulates the PTC element 2 , the diode element 3 , a part of the first conductive lead 4 , a part of the second conductive lead 5 and a part of the third conductive lead 6 . A part of the free part 42 of the first conductive lead 4 , a part of the free part 52 of the second conductive lead 5 and a part of the free part 62 of the third conductive lead 6 are exposed outside the package material 7 .

The present invention will be further described with respect to the following examples, but it should be understood that these examples are only used for illustration and should not be construed as a limitation of the implementation of the present invention.

Example

<Example 1 (E1) >

12.5 g of HDPE (purchased from Taiwan Plastics Industry Co., Ltd., product model: HDPE9002) was used as a non-grafted olefin-based polymer, and 12.5 g of HDPE grafted with maleic anhydride (purchased from DuPont, product model: MB100D) was used as Olefin-based polymer grafted with carboxylic anhydride, 25 g of carbon black powder (purchased from Columbian Chemicals, product model: Raven 430UB) was used as a conductive filler.

The above ingredients were mixed in a mixer (brand: Brabender), and the ingredients were mixed for 10 min at a temperature of 200° C. and a stirring speed of 30 rpm.

The above-obtained batch mixture was placed in a mold, and hot-pressed for 4 min at a hot-pressing temperature of 200° C. and a hot-pressing pressure of 80 kg/cm ² to form a PTC polymer layer sheet with a thickness of 0.6 mm. The sheet was taken out from the mold, and its two opposite surfaces were contacted with two copper foils (respectively as the first electrode layer and the second electrode layer), and hot pressed at 200 ° C and 80 kg/cm ² for 4 min , to form a PPTC element with a thickness of 0.67 mm. The PPTC component is then cut into a plurality of 1.0 mm × 1.0 mm small pieces (chips, hereinafter referred to as PPTC small pieces), and each PPTC small piece is irradiated with Co-60 γ-rays at a total radiation dose of 150 kGy, and then welded for one or two times. Polar body element (TVS diode, purchased from Beverly Forest Enterprise Co., Ltd., product model is SMAJ24A, thickness is 0.3 mm). In Example 1 (E1), the PPTC die and the TVS diode are connected in series. Next, the first conductive lead and the second conductive lead are respectively welded to one of the two copper foils of each PPTC chip and to the TVS diode to form the composite circuit protection device as shown in FIG. 2 .

According to Underwriter Laboratories' safety standard UL 1434 for thermistor-type devices, the holding current (hold current, that is, the maximum current value during normal operation) and trip current (that is, the maximum current value during normal operation) of PPTC chips are measured The minimum current value required by the PPTC element to reach the high resistance state), the rated voltage (that is, the voltage applicable when the PPTC element works), and the withstand voltage (that is, the maximum voltage that will not cause the PPTC element to fail or be damaged). In addition, according to Underwriter Laboratories' safety standard UL 497B for transient voltage surge suppressors, the breakdown voltage of TVS diode components (ie the voltage at which TVS diodes trigger work) and the clamping voltage (clamping voltage) are measured. voltage, that is, the maximum voltage that the TVS diode can provide). The measurement results of the properties of PPTC chips and TVS diodes are shown in Table 1, respectively. 【Table 1】 holding current trip current Rated voltage Withstand voltage PPTC small 0.01A 0.03A 60V 60V collapse voltage ^a Clamping voltage ^b TVS SMAJ24A 27V 38.9V a: Measured at 1 mA. b: Measured under pulse waveform (t _p ) 10/1000 μs and pulse current (I _p ) 10.3 A.

<Example 2 (E2) >

The process conditions of the composite circuit protection device of E2 are similar to those of E1, the difference is that after the PPTC chips are irradiated with gamma rays, a hole is drilled in the central part of each PPTC chip of E2 to form the composite circuit shown in Figure 3. type circuit protection device. Each perforation is defined by a hole-defining wall with a circular cross-section (0.15 mm in diameter and 0.0177 ^mm2 in circular area).

<Example 3 and 4 (E3 and E4) >

The process conditions of the composite circuit protection device of E3 and E4 are similar to those of E1 and E2 respectively, the difference is that in E3 and E4, the PPTC chip and the TVS diode are connected in parallel. After irradiating the PPTC small pieces with gamma rays, the first conductive lead, the second conductive lead and the third conductive lead are respectively welded to one of the two copper foils of each PPTC small piece and to the two electrodes of the TVS diode , to form a composite circuit protection device as shown in Figure 4.

<Example 5 to 8 (E5-E8) >

The process conditions of the composite circuit protection device of E5-E8 are similar to those of E1-E4 respectively, the difference is that the product model of the TVS diode of E5-E8 is SMAJ75A (purchased from Baifulin Enterprise Co., Ltd., with a thickness of 0.3 mm). The measurement results of the properties of the TVS diodes of E5-E8 are shown in Table 2. 【Table 2】 collapse voltage ^a Clamping voltage ^b TVS SMAJ75A 83.3V 121V a: Measured at 1 mA. b: Measured under pulse waveform (t _p ) 10/1000 μs and pulse current (I _p ) 3.3 A.

<Comparative Example 1 and 2 (CE1 and CE2) >

The circuit protection devices of CE1 and CE2 are the PPTC chips of E1 and E2 respectively, that is, both CE1 and CE2 do not contain TVS diodes, and the first conductive lead and the second conductive lead are respectively welded to the two PPTC chips of each PPTC chip. on a piece of copper foil.

<Comparative Example 3 and 4 (CE3 and CE4) >

The circuit protection devices of CE3 and CE4 are the TVS diodes of E1 and E5 respectively, that is, CE3 and CE4 do not contain PPTC chips, and the first conductive lead and the second conductive lead are respectively welded to each TVS diode on the two electrodes.

Table 3 shows the overall structure of the circuit protection devices of E1-E8 and CE1-CE4. 【table 3】 PPTC small Perforation of PPTC Small Pieces TVS diode Electrical connection between PPTC chip and TVS diode E1 Have -- SMAJ24A tandem E2 Have Have SMAJ24A tandem E3 Have -- SMAJ24A in parallel E4 Have Have SMAJ24A in parallel E5 Have -- SMAJ75A tandem E6 Have Have SMAJ75A tandem E7 Have -- SMAJ75A in parallel E8 Have Have SMAJ75A in parallel CE1 Have -- -- -- CE2 Have Have -- -- CE3 -- -- SMAJ24A -- CE4 -- -- SMAJ75A -- "--" means no such component.

Performance Testing

[ Surge Immunity Test (Surge immunity test)]

Take 10 circuit protection devices of E1-E4 and CE1-CE3 as test samples for surge immunity test. The surge immunity test of each test sample was performed at a voltage greater than the breakdown voltage of the TVS diode (30 V _dc or 40 V _dc ) and at a current (0.1 A or 10 A) of the overcurrent of the PPTC chip. The test is performed by turning on the first conductive lead and the second conductive lead for 60 seconds and then turning it off. If neither the PPTC chip nor the TVS diode is burnt or damaged, the test sample passes the surge immunity test, and the average value of the time when the PPTC chip is tripped (if there is a trip) is recorded. If the PPTC die or TVS diode burns out, the test sample is burnt, and the average of the time it takes to burn is recorded. The results are shown in Table 4, respectively. 【Table 4】 30V/0.1A 30V/10A 40V/0.1A 40V/10A result time(s) result time(s) result time(s) result time(s) E1 pass 0.110 pass 0.045 pass 0.095 pass 0.035 E2 pass 0.105 pass 0.040 pass 0.090 pass 0.030 E3 pass 0.105 pass 0.045 pass 0.095 pass 0.035 E4 pass 0.100 pass 0.040 pass 0.090 pass 0.030 CE1 pass 0.145 pass 0.055 pass 0.130 pass 0.040 CE2 pass 0.140 pass 0.050 pass 0.125 pass 0.040 CE3 TVS diode burned out 0.160 TVS diode burned out 0.085 TVS diode burned out 0.135 TVS diode burned out 0.045

The results in Table 4 show that the CE3 test sample containing only TVS diodes burns within 0.2 s under 0.1 A overcurrent and overvoltage (greater than the breakdown voltage of TVS diodes), or at 10 A overcurrent and overvoltage within 0.1 s, and the damage cannot be repaired. In contrast, all test samples E1-E4 containing the combination of PPTC chips and TVS diodes passed the surge immunoassay without burning. In addition, the PPTC die of E2 and E4 are formed with perforated test samples to improve heat transfer, which can further shorten the time for the PPTC die to trip, and prevent overcurrent from flowing through the TVS diode, thus protecting its TVS diode from burn. In other words, in the test samples of E1-E4, when the PPTC chip jumps off before the TVS diode burns out, its TVS diode is not damaged. In addition, although the PPTC chips of E3 and E4 are connected in parallel with the TVS diodes, their PPTC chips still trip before the TVS diodes burn out, thus protecting their TVS diodes from burning out.

In addition, 10 circuit protection devices of E5-E8 and CE1, CE2 and CE4 were taken as test samples for surge immunity test. The surge immunity test of each test sample was performed at a voltage greater than the breakdown voltage of the TVS diode (90 V _dc or 120 V _dc ) and the overcurrent of the PPTC chip (0.1 A or 5 A) before the The test is performed by turning on the first conductive lead and the second conductive lead for 60 seconds and then turning it off. If neither the PPTC chip nor the TVS diode is burnt or damaged, the test sample passes the surge immunity test, and the average value of the time when the PPTC chip is tripped (if there is a trip) is recorded. If the PPTC die or TVS diode burns out, the test sample is burnt, and the average of the time it takes to burn is recorded. The results are shown in Table 5, respectively. 【table 5】 90V/0.1A 90V/5A 120V/0.1A 120V/5A result time(s) result time(s) result time(s) result time(s) E5 pass 0.105 pass 0.040 pass 0.090 pass 0.030 E6 pass 0.100 pass 0.035 pass 0.085 pass 0.025 E7 pass 0.105 pass 0.040 pass 0.090 pass 0.030 E8 pass 0.095 pass 0.035 pass 0.085 pass 0.025 CE1 PPTC small pieces burned 0.120 PPTC small pieces burned 0.040 PPTC small pieces burned 0.115 PPTC small pieces burned 0.035 CE2 PPTC small pieces burned 0.115 PPTC small pieces burned 0.035 PPTC small pieces burned 0.115 PPTC small pieces burned 0.035 CE4 TVS diode burned out 0.255 TVS diode burned out 0.135 TVS diode burned out 0.165 TVS diode burned out 0.055

The results in Table 5 show that CE1 and CE2 test samples containing only PPTC chips were burnt under overcurrent and overvoltage of 0.1 A or 5 A (greater than the rated voltage of PPTC chips); CE4 test samples containing only TVS diodes were at 0.1 It will burn within 0.26 s under an overcurrent and overvoltage of A (greater than the breakdown voltage of the TVS diode), or within 0.14 s under an overcurrent and overvoltage of 5 A, and the damage cannot be repaired. In contrast, all test samples E5-E8 containing the combination of PPTC chips and TVS diodes passed the surge immunoassay without burning. In addition, the PPTC die of E6 and E8 are formed with perforated test samples to improve heat transfer, which can further shorten the time for the PPTC die to trip, and prevent overcurrent from flowing through the TVS diode, thus protecting its TVS diode from burn. In addition, although the PPTC die of E7 and E8 are connected in parallel with the TVS diode, their PPTC die still trips at a breakdown voltage greater than that of the TVS diode before the TVS diode burns out. In addition, although the test samples of E5-E8 were tested at an overvoltage greater than the rated voltage of the PPTC die, the sum of the breakdown voltage of the TVS diode by setting the rated voltage of the PPTC die is greater than the overvoltage of the test. , the test samples of E5-E8 can still pass the surge immunity test via the voltage division effect between the PPTC chip and the TVS diode.

In summary, with the PTC element 2 having a rated voltage ranging from 50% to 250% of the breakdown voltage of the diode element 3 measured at 1 mA, in the presence of the overcurrent and the overvoltage, The PTC element 2 can quickly trip to a high-resistance state to protect the diode element 3 from being burnt out due to overcurrent or overvoltage, so that the composite circuit protection device of the present invention can be reused, showing its excellent performance Therefore, it can indeed achieve the purpose of the present invention.

However, the above are only examples of the present invention, and should not limit the scope of the present invention. Any simple equivalent changes and modifications made according to the scope of the application for patent of the present invention and the content of the patent specification are still within the scope of the present invention. within the scope of the invention patent.

20: PTC polymer substrate 30: Electrodes 40: Hole 50: The first conductive lead 60: Second conductive lead 2:PTC components 21: PTC layer 210: Hole 211: Surface 22: The first electrode layer 23: The second electrode layer 3: Diode components 31: Diode structure 311: Surface 32: The third electrode layer 33: Fourth electrode layer 4: The first conductive lead 41: Connection part 42: Ministry of Liberty 5: Second conductive lead 51: Connection part 52: Ministry of Liberty 6: The third conductive lead 61: Connection part 62: Ministry of Liberty 7: Packaging material

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: [Fig. 1] is a three-dimensional schematic diagram of an existing plug-in PTC overcurrent protection device; [ Fig. 2 ] is a schematic cross-sectional view of the first embodiment of the composite circuit protection device of the present invention; [ FIG. 3 ] is a schematic cross-sectional view of a modification of the first embodiment; and [ FIG. 4 ] is a schematic cross-sectional view of the second embodiment of the composite circuit protection device of the present invention.

2:PTC components

21: PTC layer

211: Surface

22: The first electrode layer

23: The second electrode layer

3: Diode components

31: Diode structure

311: Surface

32: The third electrode layer

33: Fourth electrode layer

4: The first conductive lead

41: Connection part

42: Ministry of Liberty

5: Second conductive lead

51: Connection part

52: Ministry of Liberty

7: Packaging material

Claims (20)

A composite circuit protection device, comprising: a PTC element, including a PTC layer having two opposing surfaces, and The first electrode layer and the second electrode layer are respectively disposed on two opposite surfaces of the PTC layer; a diode element connected to the second electrode layer; a first conductive lead connected to the first electrode layer; and a second conductive lead connected to the diode element, Wherein the PTC element has a rated voltage ranging from 50% to 250% of the breakdown voltage of the diode element measured at 1 mA. The composite circuit protection device of claim 1, wherein the PTC element has a rated voltage ranging from 70% to 230% of the breakdown voltage of the diode element measured at 1 mA. The composite circuit protection device of claim 1, wherein the overvoltage of the composite circuit protection device is less than the sum of the rated voltage of the PTC element and the breakdown voltage of the diode element. The composite circuit protection device of claim 1, wherein the PTC element has a hole formed in the PTC layer. The composite circuit protection device of claim 4, wherein the PTC layer of the PTC element has a perimeter that defines a boundary of the PTC layer and is interconnected with two opposite surfaces of the PTC layer, and the hole is connected to the perimeter. The peripheries of the PTC layers are spaced apart. The composite circuit protection device of claim 4, wherein the hole penetrates at least one of the two opposite PTC surfaces of the PTC layer. The composite circuit protection device of claim 6, wherein the hole further penetrates at least one of the first electrode layer and the second electrode layer. The composite circuit protection device of claim 1, wherein the diode element comprises a diode structure with two opposing surfaces, a third electrode layer disposed on one of the two opposite surfaces of the diode structure and connected to the second electrode layer of the PTC element, and a fourth electrode layer disposed on the other of the two opposite surfaces of the diode structure, Wherein the second conductive lead is connected to one of the third electrode layer and the fourth electrode layer of the diode element. The composite circuit protection device as claimed in claim 8, further comprising a third conductive lead, the second conductive lead is connected to the fourth electrode layer, the third conductive lead is connected and disposed between the second electrode layer and the fourth electrode layer between the third electrode layers. The composite circuit protection device according to claim 1, wherein the PTC element and the diode element are connected in series. The composite circuit protection device of claim 1, wherein the PTC element and the diode element are connected in parallel. The composite circuit protection device of claim 1, wherein the diode element is a transient voltage suppression diode. The composite circuit protection device of claim 12, wherein the transient voltage suppression diode comprises a silicon wafer having a PN junction. The composite circuit protection device of claim 1, wherein the PTC element is a polymer PTC element, and the PTC layer is a PTC polymer layer. The composite circuit protection device of claim 14, wherein the PTC polymer layer comprises a polymer base material and a conductive filler dispersed in the polymer base material. The composite circuit protection device according to claim 15, wherein the polymer substrate is made of a polymer composition containing a non-grafted olefin-based polymer. The composite circuit protection device according to claim 16, wherein the polymer composition further comprises an olefin-based polymer grafted with carboxylic anhydride. The composite circuit protection device according to claim 15, wherein the conductive filler is selected from carbon black powder, metal powder, conductive ceramic powder or a combination of the foregoing. The composite circuit protection device according to claim 1, further comprising a packaging material, the packaging material packaging the PTC element, the diode element, a part of the first conductive lead and a part of the second conductive lead. The composite circuit protection device as claimed in claim 19, wherein the encapsulation material is made of epoxy resin.

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