TWI707515B - Composite circuit protection device - Google Patents

Abstract

A composite circuit protection device includes a PPTC element, a varistor, a first conductive lead and a second conductive lead. The PPTC device is formed with a first hole and includes a PTC polymer layer, a first electrode layer and a second electrode layer. The varistor is connected to the second electrode layer of the PPTC element. The first conductive lead is connected to the first electrode layer of the PPTC element. The second conductive lead is connected with the varistor. The composite circuit protection device of the present invention can pass the surge immunity test and has a higher maximum operating current, and thus has good durability and reliability.

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 voltage-dependent resistor and a polymer positive temperature coefficient (PPTC) element including a hole Type circuit protection device.

US 8,508,238 B1 discloses an insertable polymer positive temperature coefficient (PPTC) over-current protection device. 1, the PPTC overcurrent protection device includes a first electrode 30, a second electrode 30, a solder material, conductive leads 50, 60 connected to the first and second electrodes 30, and A positive temperature coefficient (PTC) polymer matrix 20 laminated between the first and second electrodes 30, 30. At least one hole 40 is formed in the PTC polymer matrix 20, and when the temperature of the PTC polymer matrix 20 increases, the hole 40 has an effective volume capable of accommodating the thermal expansion of the PTC polymer matrix 20.

Electrical characteristics [such as operating current and high-voltage surge endurability] are important factors for PPTC overcurrent protection devices to prevent power surges. When the working current of the PPTC overcurrent protection device is increased by increasing the thickness or area of the PTC polymer matrix 20, it is more susceptible to power surges. On the other hand, when the high voltage durability of the PPTC overcurrent protection device is increased by reducing the thickness or area of the PTC polymer matrix 20, the PPTC overcurrent protection device is not necessarily less susceptible to power surges.

Therefore, the purpose of the present invention is to provide a composite circuit protection device. The composite circuit protection device of the present invention can overcome at least one shortcoming of the prior art.

Therefore, the composite circuit protection device of the present invention includes a PPTC element, a varistor, a first conductive lead, and a second conductive lead.

The PPTC element is formed with a first hole and includes a PTC polymer layer, a first electrode layer and a second electrode layer. The PTC polymer layer has two opposite surfaces, and the first hole is formed on the PTC polymer layer. The first electrode layer and the second electrode are respectively disposed on the two opposite surfaces of the PTC polymer layer.

The varistor is connected to the second electrode layer of the PPTC element.

The first conductive lead is connected to the first electrode layer of the PPTC element.

The second conductive lead is connected with the varistor.

The effect of the present invention is that since the first hole is formed on the PTC polymer layer and the PTC polymer layer is connected to the varistor, the composite circuit protection device of the present invention can pass the surge immunity test and has better performance. High maximum operating current, which has good endurability (endurability) and reliability (reliability).

The content of the present invention will be described in detail below:

Preferably, the varistor includes: a varistor layer with two opposite surfaces, and a third electrode layer disposed on one of the two opposite surfaces of the varistor layer, and is connected to the PPTC The second electrode layer of the element is connected, and a fourth electrode layer is arranged on the other surface of the two opposite surfaces of the varistor layer, wherein the second conductive lead is connected to the third electrode layer of the varistor And one of the fourth electrode layer is connected.

More preferably, the composite circuit protection device of the present invention further includes a third conductive lead, the second conductive lead is connected to the fourth electrode layer, and the third conductive lead is disposed between the second electrode layer and the third electrode layer And connected with the second electrode layer and the third electrode layer.

More preferably, a second hole is formed in the varistor. More preferably, the second hole is formed on the varistor layer. More preferably, the varistor layer of the varistor further has a peripheral edge connecting its two opposite surfaces and defining its edge, and the second hole is spaced from the peripheral edge of the varistor layer. More preferably, the second hole extends through at least one of the two opposite surfaces of the varistor layer. More preferably, the second hole also extends through at least one of the third electrode layer and the fourth electrode layer.

More preferably, the varistor layer is made of metal oxide material.

Preferably, the PTC polymer layer of the PPTC element further has a peripheral edge connecting its two opposite surfaces and defining its edges, and the first hole is spaced from the peripheral edge of the PTC polymer layer.

Preferably, the first hole extends through at least one of the two opposite surfaces of the PTC polymer layer. More preferably, the first hole also extends through at least one of the first electrode layer and the second electrode layer.

Preferably, the PTC polymer layer of the PPTC device includes a polymer matrix and a conductive filler dispersed in the polymer matrix.

More preferably, the polymer matrix is made of a polymer composition containing a non-grafted olefin-based polymer. More preferably, the ungrafted olefin polymer is high density polyethylene (HDPE).

More preferably, the polymer composition further contains a grafted olefin-based polymer. More preferably, the grafted olefin-based polymer is a carboxylic acid anhydride-grafted olefin-based polymer.

More preferably, the conductive filler is selected from carbon black powder, metal powder, electrically conductive ceramic powder, or a combination of the foregoing.

Preferably, the composite circuit protection device of the present invention further includes an encapsulant for encapsulating the PPTC element, the varistor, part of the first conductive lead and part of the second conductive lead. More preferably, the sealing material is made of epoxy resin.

The present invention will be further described with reference to the following embodiments, but it should be understood that this embodiment is only illustrative and should not be construed as a limitation of the implementation of the present invention.

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

2 and 3, a first embodiment of the composite circuit protection device of the present invention includes a PPTC element 2, a varistor 3, a first conductive lead 4, and a second conductive lead 5. The PPTC device 2 is formed with a first hole 210 and includes a PTC polymer layer 21, a first electrode layer 22 and a second electrode layer 23. The PTC polymer layer 21 has two opposite surfaces 211, and the first and second electrode layers 22 and 23 are respectively disposed on the two opposite surfaces 211 of the PTC polymer layer 21. The varistor 3 is connected to the second electrode layer 23 of the PPTC element 2 through a welding material. The first conductive lead 4 is connected to the first electrode layer 22 of the PPTC element 2, and the second conductive lead 5 is connected to the varistor 3. The first hole 210 is formed on the PTC polymer layer 21. The PTC polymer layer 21 of the PPTC element 2 also has a peripheral edge 212 connecting its two opposite surfaces 211 and defining its edges. The first hole 210 is spaced apart from the periphery 212 of the PTC polymer layer, and the first hole 210 has an effective function that can accommodate the thermal expansion of the PTC polymer layer 21 when the temperature of the PTC polymer layer 21 rises. Volume to avoid undesirable structural deformation of the PTC polymer layer 21.

In a specific embodiment, the first hole 210 extends through at least one of the two opposite surfaces 211 of the PTC polymer layer 21, and the first hole 210 also extends through the first and second electrode layers 22 , At least one of 23. In this embodiment, the first hole 210 extends through the two opposite surfaces 211 of the PTC polymer layer 21 and the first and second electrode layers 22, 23 to form a through hole. In a specific embodiment, the first hole 210 extends along a straight line passing through the geometric center of the PTC polymer layer 21 and passing through two opposite surfaces 211 of the PTC polymer layer 21. The first hole 210 is defined by a hole-defining wall, and the hole-defining wall has a cross section parallel to the surfaces 211 of the PTC polymer layer 21. The cross-section of the hole-defining wall is round, square, elliptical, triangular, or cross-shaped.

The varistor 3 includes a varistor layer 31, a third electrode layer 32 and a fourth electrode layer 33. The varistor layer 31 has two opposite surfaces 311, and the third electrode layer 32 is disposed on one of the two opposite surfaces 311 of the varistor layer 31 and is connected to the second electrode of the PPTC element 2 The layer 23 is connected, and the fourth electrode layer 33 is disposed on the other surface of the two opposite surfaces 311 of the varistor layer 31. In a specific embodiment, the varistor layer 31 is made of a metal oxide material. The second conductive lead 5 is connected to one of the third and fourth electrode layers 32 and 33 of the varistor 3. In this embodiment, the second conductive lead 5 is disposed between the second and third electrode layers 23, 32 and is connected to the second and third electrode layers 23, 32.

The varistor layer 31 of the varistor 3 also has a peripheral edge 312 that defines its edge and connects its two opposite surfaces 311.

A second hole 310 is formed in the varistor layer 31 of the varistor 3. The second hole 310 is spaced apart from the periphery 312 of the varistor layer 31. In a specific embodiment, the second hole 310 extends through at least one of the two opposite surfaces 311 of the varistor layer 31. In a specific embodiment, the second hole 310 also extends through at least one of the third and fourth electrode layers 32, 33. In this embodiment, the second hole 310 extends through the two opposite surfaces 311 of the varistor layer 31 and the third and fourth electrode layers 32, 33 to form a through hole.

The first conductive lead 4 includes a connecting portion 41 and a free portion 42, and the second conductive lead 5 includes a connecting portion 51 and a free portion 52. In this embodiment, the connecting portion 41 of the first conductive lead 4 is connected to the outer surface of the first electrode layer 22 of the PPTC element 2 by a soldering material, and the free portion 42 extends outward from the connecting portion 41 It extends beyond the first electrode layer 22 for insertion into a pin hole (not shown) of a circuit board or circuit device. The connecting portion 51 of the second conductive lead 5 is connected to the second and third electrode layers 23, 32 through a welding material and is arranged between the second and third electrode layers 23, 32, and the free portion 52 is from The connecting portion 51 extends outwardly beyond the second and third electrode layers 23, 32 to be inserted into a lead hole (not shown) of a circuit board or circuit device.

The PTC polymer layer 21 of the PPTC element 2 includes a polymer matrix and a conductive filler dispersed in the polymer matrix. The polymer matrix is made of a polymer composition containing ungrafted olefin polymer. In a specific embodiment, the ungrafted olefin-based polymer is high density polyethylene. In a specific embodiment, the polymer composition further contains a grafted olefin polymer. In a specific embodiment, the grafted olefin-based polymer is an olefin-based polymer grafted with carboxylic anhydride. The conductive filler suitable for use in the present invention is carbon black powder, metal powder, conductive ceramic powder or a combination of the foregoing.

4 and 5, a second embodiment of the composite circuit protection device of the present invention is similar to the first embodiment. The difference is that in the second embodiment, the connecting portion 51 of the second conductive lead 5 is It is connected to the outer surface of the fourth electrode layer 33 of the varistor 3 by a soldering material, and the free portion 52 extends outward from the connection portion 51 beyond the fourth electrode layer 33 for inserting a circuit board or In the lead hole of the circuit device (not shown).

In this embodiment, the composite circuit protection device further includes a sealing material 7 encapsulating the PPTC element 2, the varistor 3, part of the first conductive lead 4 and part of the second conductive lead 5. The free parts 42 and 52 of the first and second conductive leads 4 and 5 are all exposed to the outside of the sealing material 7. In a specific implementation, the sealing material 7 is made of epoxy resin.

6 and 7, a third embodiment of the composite circuit protection device of the present invention is similar to the second embodiment, the difference is that the composite circuit protection device of the third embodiment also includes a third conductive lead 6. The third conductive lead 6 is arranged between the second and third electrode layers 23, 32 and is connected to the second and third electrode layers 23, 32. The third conductive lead 6 includes a connecting portion 61 connected to the second and third electrode layers 23, 32, and a free portion extending from the connecting portion 61 beyond the second and third electrode layers 23, 32部62. The free portion 62 is used to insert into a lead hole (not shown) of a circuit board or circuit device.

In this embodiment, the sealing material 7 encapsulates the PPTC element 2, the varistor 3, part of the first conductive lead 4, part of the second conductive lead 5 and part of the third conductive lead 6. The free parts 42, 52, and 62 of the first, second and third conductive leads 4, 5, 6 are all exposed to the outside of the sealing material 7.

Example 1 (E1)

Take 10 g of high-density polyethylene (polymer 1; manufacturer: available from Formosa Plastic Corp.; model: HDPE9002) as ungrafted olefin polymer, and 10 g as carboxylic anhydride grafted olefin polymer High-density polyethylene grafted with maleic anhydride (manufacturer: Dupont; model: MB100D), 15 g of carbon black powder (manufacturer: Columbian Chemicals; model: Raven 430UB), and 15 g of magnesium hydroxide (manufacturer: MagChem ^® MH10), mixed in a Brabender mixer. Among them, the mixing temperature is 200°C, the stirring speed is 30 rpm, and the mixing time is 10 minutes.

The kneaded mixture is hot pressed in a mold to form a PTC polymer layer sheet with a thickness of 2.25 mm. Among them, the hot pressing temperature is 200°C, the hot pressing time is 4 minutes, and the hot pressing pressure is 80 kg/cm ² .

Two copper foil sheets (respectively as the first electrode layer and the second electrode layer) were attached to the two opposite surfaces of the PTC polymer layer, and hot-pressed at 200°C and 80 kg/cm ² for 4 minutes A PTC laminate having a sandwich structure is formed. This PTC laminate was cut into multiple PTC samples with a size of 14.5 mm×14.5 mm. Each PTC sample is irradiated with cobalt-60 gamma rays (total irradiation dose is 150 kGy), and then a circular perforation is formed in the central part of each PTC sample [with 1.5 mm diameter (d) and hole area (Pd ² /4) It is 1.77 mm ² ]. Then, for each PTC sample, a first conductive lead and a second conductive lead were welded to the copper foils of the PTC sample, and then a varistor (manufacturer: Centra Science Corp.; model: 14S431KA) was welded to one of the copper foils of the PTC sample to form a composite circuit protection device as shown in Figs. 2 and 3.

Example 2~3 (E2~E3)

The steps and conditions for preparing the composite circuit protection device of Examples 2 to 3 (E2 to E3) are similar to those of Example 1, except that the positions and/or numbers of conductive leads of E2 to E3 are different from those of Example 1. In more detail, in E2, the varistor is first welded to the PTC sample, and then the first and second conductive leads are respectively welded to the outer surface of the PTC sample and the varistor to form a Figure 4 and Figure 5 show the E2 composite circuit protection device. In E3, the first conductive lead and the second conductive lead are welded to the outer surfaces of the PTC sample and the varistor, respectively, and the third conductive lead is placed between the PTC sample and the varistor. Connect the PTC sample and the varistor respectively. Therefore, E3's composite circuit protection device has the structure shown in FIGS. 6 and 7.

Example 4~6 (E4~E6)

The structure of the composite circuit protection device of E4~E6 is similar to the structure of the composite circuit protection device of E1~E3. The difference is that in E4~E6, the varistor also forms a circular perforation [with 1.5 mm The diameter (d) and hole area (Pd ² /4) are 1.77 mm ² ] (see Table 1).

Comparative example 1~2 (CE1~CE2)

The steps and conditions for preparing the composite circuit protection device of Comparative Examples 1~2 (CE1~CE2) are similar to those of Example 1, except that the composite circuit protection device of CE1 and CE2 does not contain a varistor, and the The PTC polymer layer of the CE1 composite circuit protection device has no perforations, while the PTC polymer layer of the CE2 composite circuit protection device has perforations (the same size and position as E1).

Comparative example 3~5 (CE3~CE5)

The steps and conditions for preparing the composite circuit protection device of Comparative Examples 3~5 (CE3~CE5) are similar to those of Examples 4~6 (E4~E6). The difference is that in CE3~CE5, each PTC polymer Both the layer and the varistor have no perforations.

Table 1 below summarizes the structure of the composite circuit protection device of E1~E6 and CE1~CE5, where V represents the existing structure. Table 1

＜ which performed (performance) test ＞

Working current test (hold current test)

The combined circuit protection device of E1~E6 and CE1~CE5 as the test sample is tested for working current to determine the maximum working current of the test sample.

The working current test is to apply an AC voltage of 240 V _ac at 25°C, while keeping the trip (trip), and perform the measurement for 15 minutes. The test results are summarized in Table 2. Table 2

The results show that the maximum working current of each test sample of E1~E6 is between 1.2 A and 1.4 A, while the maximum working current of CE1~CE5 is between 0.8 A and 0.9 A.

Obviously, the formation of the perforation in the PTC polymer layer and the connection of the PPTC element and the varistor will increase the maximum operating current of the composite circuit protection device of the embodiment by 20% (compared to CE1 to CE5).

Surge immunity test (surge immunity test)

A. in 400 V _ac :

Ten composite circuit protection devices made from E1~E6 and CE1~CE5 were taken as test samples for surge immunity test.

The surge immunity test of each test sample is performed in a continuous manner under a fixed voltage of 400 V _ac and different test currents of 10A, 15A and 20A, where each test current is turned on for 60 seconds and then turned off. First record the number (n) of each test sample of E1~E6 and CE1~CE5 that have passed the test without being burnt or damaged, and then calculate the pass rate (n/10×100%) of E1~E6 and CE1~CE5 respectively, and get The results are shown in Table 2.

The test results show that the pass rate of each test sample of E1~E6 is 100%, and the pass rate of each test sample of CE1~CE5 is between 20% and 60%.

Obviously, the formation of the holes in the PTC polymer layer and the connection of the PPTC element and the varistor will improve the surge protection capability of the composite circuit protection device of the embodiment.

B. in 600 V _ac :

Ten composite circuit protection devices made from E1~E6 and CE1~CE5 were taken as test samples for surge immunity test.

The surge immunity test of each test sample is carried out in a continuous manner under a fixed voltage of 600 V _ac and different test currents of 3A, 7A and 40A. In more detail, the test currents of 3A and 7A are each turned on for 60 seconds. After closing, the 40A test current is closed after 5 seconds. First record the number (n) of each test sample of E1~E6 and CE1~CE5 that have passed the test without being burnt or damaged, and then calculate the pass rate (n/10×100%) of E1~E6 and CE1~CE5 respectively, and get The results are shown in Table 2.

The test results show that the pass rate of each test sample of E1~E6 is 100%, and the pass rate of each test sample of CE1~CE5 is between 10% and 70%. The test samples of CE1~CE5, because some of the composite circuit protection devices were burned and damaged in the surge immunity test, the pass rate was lower than that of the test samples of E1~E6.

Obviously, the formation of the holes in the PTC polymer layer and the connection of the PPTC element and the varistor will improve the surge protection capability of the composite circuit protection device of the embodiment.

In summary, since the first hole is formed on the PTC polymer layer and the PTC polymer layer is connected to the varistor, the composite circuit protection device of the present invention can pass the surge immunity test and has a high The maximum working current of, so it will have good durability and reliability, so it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, all simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the content of the patent specification still belong to Within the scope of the patent for the present invention.

2‧‧‧PPTC components 21‧‧‧PTC polymer layer 210‧‧‧First hole 211‧‧‧surface 212‧‧‧Circumference 22‧‧‧First electrode layer 23‧‧‧Second electrode layer 3‧‧‧ Varistor 31‧‧‧ Varistor layer 310‧‧‧Second hole 311‧‧‧surface 312‧‧‧Circumference 32‧‧‧The third electrode layer 33‧‧‧Fourth electrode layer 4‧‧‧The first conductive lead 41‧‧‧Connecting part 42‧‧‧Freedom 5‧‧‧Second conductive lead 51‧‧‧Connecting part 52‧‧‧Freedom 6‧‧‧Third conductive lead 61‧‧‧Connecting part 62‧‧‧Ministry of Freedom 7‧‧‧Sealing material

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: 　 Figure 1 is a perspective schematic diagram illustrating a conventional pluggable PPTC overcurrent protection device; Figure 2 is a perspective schematic diagram , To illustrate a first embodiment of the composite circuit protection device of the present invention; Figure 3 is a schematic cross-sectional view illustrating the first embodiment of the present invention; Figure 4 is a perspective schematic diagram illustrating a first embodiment of the composite circuit protection device of the present invention Second embodiment; Figure 5 is a schematic cross-sectional view illustrating the second embodiment of the present invention; 　 Figure 6 is a three-dimensional schematic view illustrating a third embodiment of the composite circuit protection device of the present invention; and Figure 7 is a schematic cross-sectional view illustrating This third embodiment of the invention.

2‧‧‧PPTC components

21‧‧‧PTC polymer layer

210‧‧‧First hole

211‧‧‧surface

22‧‧‧First electrode layer

23‧‧‧Second electrode layer

3‧‧‧ Varistor

31‧‧‧ Varistor layer

310‧‧‧Second hole

311‧‧‧surface

32‧‧‧The third electrode layer

33‧‧‧Fourth electrode layer

4‧‧‧The first conductive lead

41‧‧‧Connecting part

42‧‧‧Freedom

5‧‧‧Second conductive lead

51‧‧‧Connecting part

52‧‧‧Freedom

Claims (18)

A composite circuit protection device includes: a PPTC element formed with a first hole, and including: a PTC polymer layer with two opposite surfaces, the first hole is formed on the PTC polymer layer, and A first electrode layer and a second electrode layer are respectively disposed on the two opposite surfaces of the PTC polymer layer; a varistor is connected to the second electrode layer of the PPTC element, and the varistor is formed A second hole; a first conductive lead connected to the first electrode layer of the PPTC element; and a second conductive lead connected to the varistor; wherein the varistor includes: a varistor layer, It has two opposite surfaces, a third electrode layer, which is arranged on one of the two opposite surfaces of the varistor layer and is connected to the second electrode layer of the PPTC element, and a fourth electrode layer is arranged On the other surface of the two opposite surfaces of the varistor layer, the second conductive lead is connected to one of the third electrode layer and the fourth electrode layer of the varistor. The composite circuit protection device according to claim 1, further comprising a third conductive lead, the second conductive lead is connected to the fourth electrode layer, and the third conductive lead is disposed on the second electrode layer and the third electrode layer. Between electrode layers and with the The second electrode layer is connected to the third electrode layer. The composite circuit protection device according to claim 1, wherein the PTC polymer layer of the PPTC element further has a peripheral edge connecting its two opposite surfaces and defining an edge thereof, and the first hole and the PTC polymer layer The peripheries are spaced apart. The composite circuit protection device according to claim 1, wherein the first hole extends through at least one of the two opposite surfaces of the PTC polymer layer. The composite circuit protection device according to claim 4, wherein the first hole further extends through at least one of the first electrode layer and the second electrode layer. The composite circuit protection device according to claim 1, wherein the second hole is formed on the varistor layer. The composite circuit protection device according to claim 6, wherein the piezoresistive layer of the piezoresistor further has a peripheral edge that connects its two opposite surfaces and defines an edge, and the second hole and the piezoresistor The peripheries of the layers are spaced apart. The composite circuit protection device according to claim 6, wherein the second hole extends through at least one of the two opposite surfaces of the varistor layer. The composite circuit protection device according to claim 8, wherein the second hole further extends through at least one of the third electrode layer and the fourth electrode layer. The composite circuit protection device according to claim 1, wherein the PPTC element The PTC polymer layer of the device includes a polymer matrix and a conductive filler dispersed in the polymer matrix. The composite circuit protection device according to claim 10, wherein the polymer matrix is made of a polymer composition containing an ungrafted olefin polymer. The composite circuit protection device according to claim 11, wherein the ungrafted olefin-based polymer is high-density polyethylene. The composite circuit protection device according to claim 11, wherein the polymer composition further contains a grafted olefin-based polymer. The composite circuit protection device according to claim 13, wherein the grafted olefin-based polymer is an olefin-based polymer grafted with carboxylic anhydride. The composite circuit protection device according to claim 10, 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, wherein the varistor layer is made of a metal oxide material. The composite circuit protection device according to claim 1, further comprising a sealing material encapsulating the PPTC element, the varistor, part of the first conductive lead and part of the second conductive lead. The composite circuit protection device according to claim 17, wherein the sealing material is made of epoxy resin.

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