TWI892060B - Integrated overcurrent protection device - Google Patents

Abstract

An integrated overcurrent protection device includes a PTC component, a first conductive unit, a second conductive unit, a first conductive via, and a second conductive via. The PTC component includes a first PTC body having two opposite surfaces. The first conductive unit includes a first metal layer, which includes a first electrode and a first conductive pad insulated from the first electrode. The second conductive unit includes a second metal layer, which includes a second electrode and a second conductive pad insulated from the second electrode. The first conductive via extends through the first conductive unit and the PTC component to electrically connect the first electrode and the second conductive pad. The second conductive through hole extends through the second conductive unit and the PTC element to electrically connect the second electrode and the first conductive pad.

Description

Integrated overcurrent protection device

The present invention relates to an integrated overcurrent protection device, and more particularly to an integrated overcurrent protection device having a first conductive via and a second conductive via.

Positive temperature coefficient (PTC) components have a PTC effect, which allows them to be used as an overcurrent protection device (such as a resettable fuse).

Referring to FIG. 1 , a conventional overcurrent protection device includes a PTC body 91, a first electrode 92, a second electrode 93, a first metal lead 94, and a second metal lead 95. The first electrode 92 and the second electrode 93 are disposed on opposite surfaces of the PTC body 91. The first metal lead 94 and the second metal lead 95 electrically connect the first electrode 92 and the second electrode 93, respectively. The PTC body 91 includes a polymer matrix having a crystalline region and an amorphous region, and a granular conductive filler. The granular conductive filler is dispersed in the amorphous region of the polymer matrix and forms a continuous conductive path for electrically connecting the first electrode 92 and the second electrode 93. The PTC effect occurs when the temperature of the polymer matrix in the crystalline region is raised to its melting point, causing the crystals in the crystalline region to melt, thereby creating a new amorphous region. When the new amorphous region grows to the point where it merges with the original amorphous region, the conductive path of the granular conductive filler becomes discontinuous, and the resistance of the PTC polymer unit increases dramatically, resulting in electrical disconnection between the first electrode 92 and the second electrode 93. However, the electrical performance and reliability of the above-mentioned overcurrent protection device are not ideal.

Therefore, the object of the present invention is to provide an integrated overcurrent protection device that can overcome at least one disadvantage of the above-mentioned prior art.

Therefore, the integrated overcurrent protection device of the present invention includes a PTC element, a first conductive unit, a second conductive unit, a first conductive through-hole and a second conductive through-hole. The PTC element includes a first PTC body, and the PTC element has two opposite first and second surfaces. The first conductive unit includes a first metal layer disposed on the first surface, the first metal layer including a first electrode and a first conductive pad insulated from the first electrode. The second conductive unit includes a second metal layer disposed on the second surface, the second metal layer including a second electrode and a second conductive pad insulated from the second electrode. The first conductive through-hole extends through the first conductive unit and the PTC element to electrically connect the first electrode and the second conductive pad. The second conductive through hole extends through the second conductive unit and the PTC element to electrically connect the second electrode and the first conductive pad.

The effect of the present invention is that the integrated overcurrent protection device can improve conductivity and has good electrical properties and reliability.

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

In addition, directional terms (e.g., top, bottom, upper, lower, upward, downward) used in the present specification and patent application are merely intended to help describe the relative positions of the components of the present invention, and are not intended to limit the actual position of each component when the present invention is actually implemented.

2 , the first embodiment of the integrated over-current protection device of the present invention includes a PTC element 20 , a first conductive unit, a second conductive unit, a first conductive via 51 , and a second conductive via 52 .

The PTC element 20 includes a first PTC body 23, and the PTC element 20 has two opposite first surfaces 21 and a second surface 22. The first PTC body 23 is a PTC polymer layer, which includes a polymer matrix and a conductive filler dispersed in the polymer matrix. The polymer matrix is made of a polymer composition, which contains a non-grafted olefin polymer. In some specific embodiments of the present invention, the non-grafted olefin polymer is high-density polyethylene (HDPE). In some specific embodiments of the present invention, the polymer composition further includes an olefin polymer grafted with a carboxylic anhydride. The conductive filler may include but is not limited to carbon black powder, metal powder, conductive ceramic powder or a combination thereof.

The first conductive unit includes a first metal layer 30 disposed on the first surface 21. The first metal layer 30 includes a first electrode 31 and a first conductive pad 41 insulated from the first electrode 31. In some embodiments of the present invention, a first trench 71 is formed in the first metal layer 30 to expose the first surface 21 and insulate the first electrode 31 from the first conductive pad 41. The first trench 71 can be formed into a predetermined shape by conventional etching and cutting techniques. The first metal layer 30 can be copper foil (e.g., nickel-plated copper foil).

The second conductive unit includes a second metal layer 40 disposed on the second surface 22. The second metal layer 40 includes a second electrode 32 and a second conductive pad 42 insulated from the second electrode 32. In some embodiments of the present invention, a second trench 72 is formed in the second metal layer 40 to expose the second surface 22 and insulate the second electrode 32 from the second conductive pad 42. The second trench 72 can be formed into a predetermined shape by conventional etching and cutting techniques. The material of the second metal layer 40 can be the same as or different from that of the first metal layer 30.

The first conductive through hole 51 extends through the first conductive unit and the PTC element 20 to electrically connect the first electrode 31 and the second conductive pad 42. In some specific embodiments of the present invention, the first conductive through hole 51 also extends through the second conductive unit.

The second conductive via 52 extends through the second conductive unit and the PTC element 20 to electrically connect the second electrode 32 and the first conductive pad 41. In some embodiments of the present invention, the second conductive via 52 also extends through the first conductive unit. In these embodiments, both the first conductive via 51 and the second conductive via 52 extend through the first conductive unit, the second conductive unit, and the PTC element 20.

The integrated overcurrent protection device has an upper surface (i.e., the top surface of the first metal layer 30 opposite the first surface 21), a lower surface (i.e., the bottom surface of the second metal layer 40 opposite the second surface 22), and sidewalls interconnecting the upper and lower surfaces. In some embodiments of the present invention, at least one of the first conductive via 51 and the second conductive via 52 is spaced apart from the sidewall of the integrated overcurrent protection device, meaning that at least one of the first conductive via 51 and the second conductive via 52 is not exposed to the sidewall of the integrated overcurrent protection device.

Referring to FIG. 3 , the second embodiment of the integrated overcurrent protection device of the present invention is similar to the first embodiment, except that the second conductive unit further includes a first insulating layer 61 and a third metal layer 62. The first insulating layer 61 is disposed between the PTC element 20 and the second metal layer 40 and is partially exposed to the second metal layer 40 via the second trench 72. The third metal layer 62 is disposed between the PTC element 20 and the first insulating layer 61. The first conductive via 51 also extends through the first insulating layer 61 and the third metal layer 62. The material of the third metal layer 62 may be the same as or different from that of the first metal layer 30. The first insulating layer 61 can be made of an electrically insulating material (such as epoxy resin).

Referring to FIG. 4 , the third embodiment of the integrated overcurrent protection device of the present invention is similar to the second embodiment, except that the first conductive unit further includes a second insulating layer 63 and a fourth metal layer 64. The second insulating layer 63 is disposed between the PTC element 20 and the first metal layer 30 and is partially exposed to the first metal layer 30 via the first trench 71. The fourth metal layer 64 is disposed between the PTC element 20 and the second insulating layer 63. The second conductive via 52 also extends through the second insulating layer 63 and the fourth metal layer 64. The material of the fourth metal layer 64 can be the same as or different from that of the first metal layer 30. The material of the second insulating layer 63 may be the same as or different from that of the first insulating layer 61 .

Referring to Figures 5 to 7 , the fourth, fifth, and sixth embodiments of the integrated overcurrent protection device of the present invention are similar to the first, second, and third embodiments, respectively, except that the PTC element 20 further includes a second PTC body 24, a PTC insulation layer 25, a first PTC metal layer 26, and a second PTC metal layer 27. The PTC insulation layer 25 is disposed between the first PTC body 23 and the second PTC body 24. The first PTC metal layer 26 is disposed between the PTC insulation layer 25 and the first PTC body 23. The second PTC metal layer 27 is disposed between the PTC insulating layer 25 and the second PTC body 24.

Each first conductive via 51 and each second conductive via 52 extends through the first PTC body 23, the second PTC body 24, the first PTC metal layer 26, the second PTC metal layer 27, and the PTC insulation layer 25. The first PTC body 23 and the second PTC body 24 are electrically connected in parallel via the first conductive via 51, the second conductive via 52, the first PTC metal layer 26, and the second PTC metal layer 27. When the first PTC body 23 and the second PTC body 24 are electrically connected in parallel, the integrated overcurrent protection device exhibits a low resistance.

The material of the second PTC body 24 can be the same as or different from that of the first PTC body 23. The material of each first PTC metal layer 26 and each second PTC metal layer 27 can be the same as or different from that of the first metal layer 30. The PTC insulation layer 25 can be made of epoxy resin.

In some other specific embodiments of the present invention, as needed, each first conductive unit and each second conductive unit may include an additional metal layer and an additional insulating layer, and the PTC element 20 may include an additional PTC body, an additional PTC metal layer, and an additional PTC insulating layer.

The present invention will be further described with reference to the following embodiments. However, it should be understood that these embodiments are for illustration only and should not be construed as limiting the implementation of the present invention.

Embodiment

<Example 1 (E1) >

First, 10.25 g of HDPE (purchased from Taiwan Plastics Industry Co., Ltd., product number: HDPE9002) was used as the non-grafted olefin polymer, 10.25 g of maleic anhydride-grafted HDPE (purchased from DuPont, product number: MB100D) was used as the carboxylic anhydride-grafted olefin polymer, and 29.5 g of carbon black powder (purchased from Columbian Chemicals, product number: Raven 430UB) was used as the conductive filler. These ingredients were mixed in a Brabender mixer at 200°C and 30 rpm for 10 minutes to obtain a mixture.

The resulting mixture was placed in a mold and hot-pressed at 200°C and 80 kg/ ^cm² for 4 minutes to produce a first PTC layer sheet with a thickness of 0.35 mm. This first PTC layer sheet was sandwiched between two nickel-coated copper foils (serving as the first and second metal layers) and hot-pressed at 200°C and 80 kg/ ^cm² for 4 minutes to produce a PTC laminate with a thickness of 0.42 mm. The PTC laminate was then cut into small pieces measuring 8.0 mm x 14.7 mm and irradiated with Co-60 gamma rays at a total radiation dose of 150 kGy.

Each PTC chip is drilled to form two through-holes extending through the first metal layer, the second metal layer, and the first PTC layer sheet, followed by electroplating to form a first conductive via and a second conductive via. The first and second metal layers on each PTC chip are then etched and trimmed to pattern the topography to form a first trench and a second trench extending through the first and second metal layers, respectively, to expose the first PTC layer sheet. The first metal layer thereby forms a first electrode and a first conductive pad insulated from each other by the first trench; the second metal layer thereby forms a second electrode and a second conductive pad insulated from each other by the second trench. The first electrode is electrically connected to the second conductive pad via the first conductive via, and the second electrode is electrically connected to the first conductive pad via the second conductive via. Thus, an integrated overcurrent protection device E1 is obtained, which has the structure shown in FIG2 .

＜Example 2 (E2) >

The manufacturing process conditions for the E2 integrated overcurrent protection device are similar to those for the E1. The difference lies in that during the formation of the PTC laminate, a 0.1 mm thick epoxy resin (as the first insulating layer) is formed between the first PTC laminate and the second metal layer, and another nickel-coated copper foil (as the third metal layer) is formed between the first PTC laminate and the first insulating layer, resulting in a PTC laminate with a thickness of 0.56 mm. In addition, the second trench exposes the first insulating layer rather than the first PTC laminate, and the first and second conductive vias extend through the first insulating layer and the third metal layer. In this way, the integrated over-current protection device E2 is obtained, which has the structure shown in FIG3 .

<Example 3 (E3) >

The manufacturing process conditions for the E3 integrated overcurrent protection device are similar to those for the E2. The difference lies in that during the formation of the PTC laminate, another epoxy resin (as a second insulating layer) is formed between the first PTC laminate and the first metal layer, and another nickel-coated copper foil (as a fourth metal layer) is formed between the first PTC laminate and the second insulating layer, resulting in a PTC laminate with a thickness of 0.69 mm. In addition, the first trench exposes the second insulating layer rather than the first PTC laminate, and the first and second conductive vias extend through the second insulating layer and the fourth metal layer. In this way, the integrated over-current protection device E3 is obtained, which has the structure shown in FIG4 .

<Example 4 to 6 (E4-E6) >

The manufacturing process conditions of the integrated overcurrent protection devices of E4-E6 are similar to those of E1-E3. The difference is that during the process of forming the PTC laminate, a second PTC layer sheet (made of the same material as the first PTC layer sheet) is formed between the first PTC layer sheet and the second metal layer, another epoxy resin (as a PTC insulating layer) is formed between the first PTC layer sheet and the second PTC layer sheet, and two other nickel-plated copper foils (as the first PTC metal layer and the second PTC metal layer) are formed between the PTC insulating layer and the first PTC body and between the PTC insulating layer and the second PTC body, respectively, to obtain a thickness of 0.94 mm. The PTC laminate has a diameter of 1.08 mm, 1.21 mm, and 1.21 mm. Furthermore, the first conductive via and the second conductive via extend through the second PTC sheet, the PTC insulation layer, the first PTC metal layer, and the second PTC metal layer, and the first PTC sheet and the second PTC sheet are electrically connected in parallel. This results in integrated overcurrent protection devices E4-E6, respectively, having the structures shown in Figures 5-7.

Comparative Example 1 (CE1) >

The manufacturing process conditions for the CE1 integrated overcurrent protection device are similar to those for the E1. The only difference is that no holes are drilled into the PTC die, and the first and second metal layers on the PTC die are not etched or trimmed. In other words, no first conductive vias, second conductive vias, first trenches, or second trenches are formed. Instead, first and second metal leads are electrically connected to the first and second metal layers, respectively. This results in the CE1 integrated overcurrent protection device, which has the structure shown in Figure 1.

Performance Testing

[ Resistance test ]

Ten integrated overcurrent protection devices (ICPs) from E1 to E6 and CE1 were selected as test samples and subjected to resistance testing to determine their initial resistance (R _i ).

The resistance test was conducted using an ohmmeter to measure the initial resistance of each test sample in accordance with UL 1434, the safety standard for thermistor-type devices issued by Underwriter Laboratories. The average values of the test results are shown in Table 1. Initial resistance (R _i , ohm) Jump time (s) Switching cycle test Aging test R _f1 (ohm) R _f1 /R _i ×100% R _f2 (ohm) R _f2 /R _i ×100% E1 0.017 8.5 0.298 1753% 0.108 635% E2 0.016 8.2 0.275 1719% 0.095 594% E3 0.016 8.0 0.265 1656% 0.080 500% E4 0.009 9.6 0.125 1389% 0.030 333% E5 0.008 9.7 0.106 1325% 0.024 300% E6 0.008 9.8 0.105 1313% 0.022 275% CE1 0.021 11.5 0.488 2324% 0.214 1019%

The results in Table 1 show that the average initial resistance of the test samples E1-E6 ranges from 0.008 ohm to 0.017 ohm, significantly lower than the test sample CE1 (0.021 ohm).

[ Trip time test (Time-to-trip test)]

Ten integrated overcurrent protection devices (ICPs) from E1 to E6 and CE1 were selected as test samples and subjected to a trip time test to determine their trip times.

The trip time test measured the trip time of each test sample in accordance with Underwriter Laboratories' UL 1434 safety standard for thermistor-type devices. A power supply (purchased from Qinghong Electronics Co., Ltd., model number: DSP-060-050HD) applied a constant voltage of 16 V _DC and a trip current of 13 A. The average test results are shown in Table 1.

The results in Table 1 show that the average trip time of the E1-E6 test samples ranges from 8.0 s to 9.8 s, significantly lower than that of the CE1 test sample (11.5 s).

[ Switching cycle test (Switching cycle test)]

Ten integrated overcurrent protection devices (ICPs) E1-E6 and CE1 were selected as test samples and subjected to a switching cycle test to determine the resistance change of the test samples.

The switching cycle test measures the post-test resistance (R _f1 ) of each test sample and calculates the resistance change rate (R _f1 /R _i × 100%) in accordance with UL 1434, the safety standard for thermistor-type devices issued by Underwriter Laboratories. Using a power supply (purchased from Qinghong Electronics Enterprise Co., Ltd., model number: _DSP -060-050HD), the test samples E1-E6 and CE1 were switched on for 60 seconds and then off for 60 seconds, with 6000 switching cycles repeated. The post-test resistance of each test sample was measured, and the resistance change rate was calculated. The average test results are shown in Table 1.

The results in Table 1 show that the average resistance variation of test samples E1-E6 ranges from 1313% to 1753%, significantly lower than that of test sample CE1 (2324%).

[ Aging test (Aging test)]

Ten integrated overcurrent protection devices (ICPs) from E1 to E6 and CE1 were selected as test samples and subjected to aging tests to determine the resistance change of the test samples.

The aging test was conducted in accordance with UL 1434, the Underwriter Laboratories safety standard for thermistor-type devices. The post-test resistance (R _f2 ) of each test sample was measured and the resistance change rate (R _f2 /R _i × 100%) was calculated. A power supply (purchased from Qinghong Electronics Enterprise Co., Ltd., product model: DSP-060-050HD) was used to apply 16 V _DC and 100 A for 1000 hours. The post-test resistance of each test sample was measured and the resistance change rate was calculated. The average test results are shown in Table 1.

The results in Table 1 show that the average resistance variation of test samples E1-E6 ranges from 275% to 635%, significantly lower than that of test sample CE1 (1019%).

In summary, the integrated overcurrent protection device of the present invention improves conductivity and has good electrical properties and reliability by forming the first conductive via 51 and the second conductive via 52 to electrically connect the first electrode 31 and the second conductive pad 42, and to electrically connect the second electrode 32 and the first conductive pad 41. Therefore, the purpose of the present invention can be achieved.

However, the above description is merely an example of the present invention and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made within the scope of the patent application and the contents of the patent specification of the present invention are still within the scope of the present patent.

91: PTC body 92: First electrode 93: Second electrode 94: First metal lead 95: Second metal lead 20: PTC element 21: First surface 22: Second surface 23: First PTC body 24: Second PTC body 25: PTC insulation layer 26: First PTC metal layer 27: Second PTC metal layer 30: First metal layer 31: First electrode 32: Second electrode 40: Second metal layer 41: First conductive gasket 42: Second conductive gasket 51: First conductive via 52: Second conductive via 61: First insulating layer 62: Third metal layer 63: Second insulation layer 64: Fourth metal layer 71: First trench 72: Second trench

Other features and functions of the present invention are clearly illustrated in the accompanying drawings, wherein: Figure 1 is a schematic perspective view of a conventional overcurrent protection device; Figure 2 is a schematic perspective view of a first embodiment of an integrated overcurrent protection device of the present invention; Figure 3 is a schematic perspective view of a second embodiment of an integrated overcurrent protection device of the present invention; Figure 4 is a schematic perspective view of a third embodiment of an integrated overcurrent protection device of the present invention; Figure 5 is a schematic perspective view of a fourth embodiment of an integrated overcurrent protection device of the present invention; Figure 6 is a schematic perspective view of a fifth embodiment of an integrated overcurrent protection device of the present invention; and Figure 7 is a schematic perspective view of a sixth embodiment of an integrated overcurrent protection device of the present invention.

20:PTC components

21: First Surface

22: Second Surface

23: First PTC body

30: First metal layer

31: First electrode

32: Second electrode

40: Second metal layer

41: First conductive pad

42: Second conductive pad

51: First conductive via

52: Second conductive via

71: First Groove

72: Second Groove

Claims (6)

An integrated overcurrent protection device comprises: a PTC element, comprising a first PTC body, and the PTC element has two opposite first and second surfaces; a first conductive unit, comprising a first metal layer disposed on the first surface, the first metal layer comprising a first electrode and a first conductive pad insulated from the first electrode, the first metal layer forming a first groove to expose the first surface and insulate the first electrode from the first conductive pad; a second conductive unit, comprising a first conductive pad disposed on the second surface A second metal layer on the surface includes a second electrode and a second conductive pad insulated from the second electrode, the second metal layer forming a second trench to expose the second surface and insulate the second electrode from the second conductive pad; a first conductive through-hole extending through the first conductive unit and the PTC element to electrically connect the first electrode and the second conductive pad; and a second conductive through-hole extending through the second conductive unit and the PTC element to electrically connect the second electrode and the first conductive pad. An integrated over-current protection device as described in claim 1, wherein at least one of the first conductive via and the second conductive via is spaced apart from the side wall of the integrated over-current protection device, and the side wall of the integrated over-current protection device is interconnected to the top surface of the first metal layer opposite to the first surface and the bottom surface of the second metal layer opposite to the second surface. The integrated overcurrent protection device as described in claim 1, wherein the PTC element further includes: a second PTC body; a PTC insulation layer disposed between the first PTC body and the second PTC body; a first PTC metal layer disposed between the PTC insulation layer and the first PTC body; and a second PTC metal layer disposed between the PTC insulation layer and the second PTC body. The integrated overcurrent protection device as described in claim 3, wherein the first PTC body and the second PTC body are electrically connected to each other in parallel. The integrated over-current protection device as described in claim 1, wherein the first conductive through-hole also extends through the second conductive unit. The integrated over-current protection device as described in claim 1, wherein the second conductive through-hole also extends through the first conductive unit.