Protective element

Abstract

A protection element comprises a fuse element, an electrode group and a heating element. The fuse element is provided with a core metal layer and a bottom metal layer below the core metal layer, and the melting point of the bottom metal layer is lower than that of the core metal layer. The electrode group includes a first electrode, a second electrode, and an auxiliary electrode. The auxiliary electrode is located between the first electrode and the second electrode and is arranged below the fuse element so as to contact the bottom metal layer. The fuse element is provided with a hollow part penetrating through the core metal layer, so that the bottom metal layer on the auxiliary electrode is exposed. The heating element is arranged below the auxiliary electrode, so that the heating element is heated and the fusing element is fused when overvoltage occurs.

Description

Technical Field

[0001] The present invention relates to a protection element, and more particularly to a fast-blow protection element. Background Art

[0002] Current protection components that cut off overcurrent are widely known as current fuses made of low-melting-point metals such as lead, tin, and antimony. Subsequently, protection components have been developed to prevent overcurrent and overvoltage. These components consist of a heating layer and a low-melting-point metal layer stacked sequentially on a flat substrate. When an overvoltage occurs, the heating element generates heat, which is transferred upward from the bottom, heating the electrode carrying the low-melting-point metal, melting the low-melting-point metal and cutting off the current, thereby protecting the associated circuits or electronic devices.

[0003] In recent years, mobile devices have become increasingly popular. Information products such as cell phones, computers, and personal assistants are ubiquitous, leading to a growing dependence on these products. However, news reports frequently surface about batteries in portable electronic devices like cell phones exploding during charging and discharging. Consequently, manufacturers have gradually refined the design of overcurrent and overvoltage protection components, enhancing battery protection during the charging and discharging process to prevent explosions caused by overvoltage or overcurrent.

[0004] The protection element works by connecting the fuse in the protection element in series with the battery's circuit, and electrically connecting the low-melting-point metal layer and the heating layer in the protection element to a switch and an integrated circuit (IC). In this way, when the IC detects an overvoltage, it activates the switch, turning it on, allowing current to flow through the heating layer in the protection element. This heats the heating layer and melts the fuse, thereby disconnecting the battery circuit and achieving overvoltage protection. Those skilled in the art will also fully understand that when an overcurrent occurs, the large amount of current flowing through the fuse causes it to heat up and melt, thereby achieving overcurrent protection.

[0005] like Figure 1 and Figure 2 As shown, Figure 1 A top view of a conventional protection element 10 is shown. Figure 2 show Figure 1 The main components of the conventional protection element 10 include a fuse 15, an electrode assembly, and a heating element 13. The fuse 15 is composed of a core metal layer 15b and at least one low melting point layer (e.g., Figure 2The bottom metal layer 15a and the top low-melting material layer 15c below and above the core metal layer 15b can be quickly fused when overvoltage, overcurrent and / or overtemperature occurs, thereby playing a protective role for the electronic product. The electrode group includes a first electrode 12a, a second electrode 12b, a third electrode 12c, a fourth electrode 12d and an auxiliary electrode 12e. The first electrode 12a, the second electrode 12b, the third electrode 12c and the fourth electrode 12d are printed on the substrate 11, and the auxiliary electrode 12e is pulled out perpendicularly to the third electrode 12c and then extends to the right in the plan view parallel to the substrate 11. The first electrode 12a and the second electrode 12b are electrically connected to the power input terminal and the power output terminal. The fuse 15 is connected in series with the electronic product (such as a battery) to be protected across the first electrode 12a and the second electrode 12b. When the current is too large or the temperature is too high, the fuse 15 will be fused due to overheating. In addition, a heating element 13 is additionally provided below the fuse 15 to actively fuse the fuse 15. The heating element 13 is arranged on the substrate 11 and connected to the third electrode 12c and the fourth electrode 12d. An insulating layer 14 is arranged between the heating element 13 and the auxiliary electrode 12e. The fuse 15 and the heating element 13 are electrically connected to a switch and a detection element (not shown). When the detection element measures an overvoltage, the switch is switched to make the heating element 13 in an electrically conductive state. The current flows through the heating element 13, so that the heating element 13 generates heat to fuse the fuse 15.

[0006] It should be noted that in order to accelerate the fusing rate of the fuse 15, at least one additional low-melting layer is added in the prior art, which also causes some problems, which will be described in detail as follows. The low-melting layer can be the bottom metal layer 15a. The bottom metal layer 15a is arranged below the core metal layer 15a and corresponds to the first electrode 12a, the auxiliary electrode 12e and the second electrode 12b. However, the auxiliary electrode 12e is below the middle of the fuse 15, which is also the breaking point of the fuse 15, and has a relatively strict requirement for the coverage area of the bottom metal layer 15a above it. For example, if the bottom metal layer 15a completely covers the auxiliary electrode 12e below it, it often causes the amount of molten metal of the protection element 10 to be too large when the protection element 10 is activated. This can cause the fuse 15 to be unable to completely disconnect, or increase the probability of reconnection at the disconnection point, thereby reducing the fusing rate. In addition, the bottom metal layer 15a is usually arranged by printing, which is difficult to accurately control the coverage area or coverage amount. Therefore, the prior protection element still has considerable room for improvement. SUMMARY

[0007] The present application provides a protection element including a fuse, an electrode set, and a heating element. The fuse has a core metal layer and a bottom metal layer disposed below the core metal layer. The electrode set has a first electrode, a second electrode, and an auxiliary electrode. The two ends of the fuse are connected to the first electrode and the second electrode, respectively, and the auxiliary electrode is disposed below the center of the fuse and contacts the bottom metal layer. The present application intentionally removes part of the fuse above the auxiliary electrode to form a hollow portion. The hollow portion penetrates the core metal layer and exposes the bottom metal layer, and the top view area of the hollow portion and the top view area of the bottom metal layer can be adjusted independently. That is, on the auxiliary electrode, the area of the core metal layer under the top view (i.e. the overlap area below) and the coverage area of the bottom metal layer can be adjusted independently, thereby accelerating the melting time of the protection element during operation.

[0008] According to an embodiment of the present application, a protection element includes a fuse, an electrode set, and a heating element. The fuse has a core metal layer and a bottom metal layer disposed below the core metal layer, and the melting point of the bottom metal layer is lower than that of the core metal layer. The electrode set has a first electrode, a second electrode, and an auxiliary electrode. The two ends of the fuse are connected to the first electrode and the second electrode, respectively, and the auxiliary electrode is disposed below the fuse between the first electrode and the second electrode, thereby contacting the bottom metal layer. The fuse has a hollow portion penetrating the core metal layer, thereby exposing the bottom metal layer above the auxiliary electrode. The heating element is disposed below the auxiliary electrode, thereby heating and causing the fuse to melt when an overvoltage occurs.

[0009] According to some embodiments, the core metal layer and the auxiliary electrode have an overlap area under the top view. The hollow portion has a first top view area under the top view. The overlap area is 10% to 83% based on the sum of the overlap area and the first top view area being 100%.

[0010] According to some embodiments, the hollow portion completely overlaps the auxiliary electrode under the top view.

[0011] According to some embodiments, the bottom metal layer above the auxiliary electrode has a second top view area under the top view. The second top view area of the bottom metal layer is 50% to 90% based on the sum of the overlap area and the first top view area being 100%.

[0012] According to some embodiments, the fuse member extends along a first direction from the first electrode to the second electrode and has a first length parallel to the first direction and a first width parallel to a second direction, wherein the first direction is perpendicular to the second direction. The auxiliary electrode extends along the second direction from one side of the fuse member to another side of the fuse member under a top view and has an electrode width parallel to the first direction, whereby the fuse member and the auxiliary electrode are cross-disposed to form an overlapping region. The hollow portion is located in the overlapping region and has a second length parallel to the second direction and a second width parallel to the first direction. A ratio of the second length of the hollow portion divided by the first width of the fuse member is less than 0.9, and the second width of the hollow portion is less than the electrode width of the auxiliary electrode.

[0013] According to some embodiments, the hollow portion has a shape under a top view that is rectangular, cross-shaped, or diamond-shaped.

[0014] According to some embodiments, the bottom metal layer on the auxiliary electrode is divided into a plurality of blocks under a top view.

[0015] According to some embodiments, a shortest distance between any two adjacent blocks is at least 0.1 mm.

[0016] According to some embodiments, a thickness of the core metal layer is 0.01 mm to 0.3 mm.

[0017] According to some embodiments, a thickness of the bottom metal layer is 0.1 mm to 1 mm.

[0018] According to some embodiments, the core metal layer is composed of a single layer, wherein the core metal layer is a tin-silver-lead alloy, a tin-silver-copper alloy, a tin-silver-bismuth alloy, or a tin-zinc alloy.

[0019] According to some embodiments, the core metal layer is composed of a plurality of layer metal layers, wherein the core metal layer is a three-layer structure stacked in order by a tin layer, a silver layer, and a tin layer, or stacked in order by a silver layer, a tin layer, and a silver layer.

[0020] According to some embodiments, the core metal layer is composed of a plurality of layer metal layers, wherein the core metal layer is a five-layer structure stacked in order by a silver layer, a tin layer, a silver layer, a tin layer, and a silver layer, or stacked in order by a tin layer, a silver layer, a tin layer, a silver layer, and a tin layer.

[0021] According to some embodiments, the bottom metal layer comprises tin, a tin-silver-copper alloy, a tin-silver-lead alloy, a tin-bismuth alloy, or a combination thereof.

[0022] According to some embodiments, the heating member comprises ruthenium oxide, a nickel-chromium alloy, a lead-germanium alloy, a silicon-germanium alloy, or a combination thereof.

[0023] According to some embodiments, further comprising a substrate and an insulating layer, wherein the heating member is disposed on the substrate, and the insulating layer is disposed between the auxiliary electrode and the heating member and extends to the substrate.

[0024] According to some embodiments, the insulating layer comprises glass, glass-ceramic, alumina, silicon carbide, silicon magnesium nitride, or a combination thereof.

[0025] According to an embodiment of the present application, a protection element includes a fuse, an electrode set, and a heating element. The fuse has a core metal layer and a bottom metal layer disposed below the core metal layer, and the bottom metal layer has a lower melting point than the core metal layer. The electrode set has a first electrode, a second electrode, and an auxiliary electrode. The two ends of the fuse are connected to the first electrode and the second electrode, respectively, and the auxiliary electrode is disposed below the fuse, thereby contacting the bottom metal layer. The core metal layer and the auxiliary electrode have an overlapping region in a top view, and the core metal layer in the overlapping region has no hollow part. The bottom metal layer on the auxiliary electrode has a top view area that is less than 100% of the top view area of the overlapping region. The heating element is disposed below the auxiliary electrode, thereby heating up and causing the fuse to melt when an overvoltage occurs.

[0026] According to some embodiments, the bottom metal layer on the auxiliary electrode has a top view area that is 30% to 79% of the top view area of the overlapping region.

[0027] According to some embodiments, the bottom metal layer on the auxiliary electrode is composed of a plurality of blocks in a top view.

[0028] According to some embodiments, the blocks of the bottom metal layer are a first block and a second block, and the fuse has a first long side and a second long side opposite to the first long side in a top view, wherein the first block and the second block both extend from the first long side to the second long side, and the first block and the second block have a shortest distance of at least 0.1 mm therebetween.

[0029] According to some embodiments, the fuse has a first long side and a second long side opposite to the first long side in a top view, and the bottom metal layer discontinuously extends from the first long side to the second long side, thereby being divided into the blocks of a first block, a second block, and a third block, wherein the first block overlaps the first long side, the third block overlaps the second long side, and the second block is between the first block and the third block, and any two adjacent ones of the blocks have a shortest distance of at least 0.1 mm therebetween.

[0030] According to some embodiments, the blocks of the bottom metal layer are a first block, a second block, a third block, and a fourth block, and the fuse has a first long side and a second long side opposite to the first long side in a top view, wherein the blocks do not overlap the first long side and the second long side, and the blocks do not extend to the edges of the auxiliary electrode, and any two adjacent ones of the blocks have a shortest distance of at least 0.1 mm therebetween. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 a top view showing a protective element of the prior art;

[0032] Figure 2 a cross-sectional view of the protective element of Figure 1

[0033] Figure 3 a top view showing a protective element of the present invention;

[0034] Figure 4 a cross-sectional view of the protective element of Figure 3

[0035] a top view showing a protective element of the present invention; Figure 5a

[0036] a cross-sectional view of the protective element of Figure 5b Figure 5a an embodiment of the protective element of

[0037] Figures 6 to 10 various embodiments of the protective element of Figure 3

[0038] BRIEF DESCRIPTION OF DRAWINGS

[0039] 10, 20 protective element

[0040] 11, 21 substrate

[0041] 12a, 22a first electrode

[0042] 12b, 22b second electrode

[0043] 12c, 22c third electrode

[0044] 12d, 22d fourth electrode

[0045] 12e, 22e auxiliary electrode

[0046] 13, 23 heating member

[0047] 14, 24 insulating layer

[0048] 15, 25 fusing member

[0049] 15a, 25a bottom metal layer

[0050] 15b, 25b core metal layer

[0051] 15c, 25c top low-melting material layer

[0052] a1, b1, c1 first block

[0053] a2, b2, c2 second block ​​​

[0054] b3, c3 third block

[0055] c4 fourth block

[0056] d distance

[0057] L1 first length

[0058] L2 second length

[0059] L3 third length

[0060] H hollow

[0061] O overlap area

[0062] P1 first end point

[0063] P2 intermediate point

[0064] P3 second end point

[0065] S1 first long side

[0066] S2 second long side

[0067] W1 first width

[0068] W2 second width

[0069] W3 electrode width DETAILED DESCRIPTION

[0070] In order to make the above and other technical contents, features and advantages of the present application more apparent and easily understood, the following relevant embodiments are specifically described below, and the accompanying drawings are referred to for detailed description.

[0071] Please refer to Figure 3 and Figure 4 , Figure 3 shows a top view of the protective element 20 of the present application, Figure 4 shows Figure 3A cross-sectional view of the protection element 20 along line AA is shown. The main components of the protection element 20 include a fuse 25, an electrode assembly, and a heater 23. The fuse 25 comprises a core metal layer 25b and at least one low-melting-point layer. It can be quickly melted in the event of overvoltage, overcurrent, and / or overtemperature, thereby protecting the electronic product. The core metal layer 25b can be a single layer or multiple layers. In one embodiment, the core metal layer 25b is composed of a single layer, such as a tin-silver-lead alloy, a tin-silver-copper alloy, a tin-silver-bismuth alloy, or a tin-zinc alloy. In one embodiment, the core metal 25b has a three-layer structure, sequentially stacked by a tin layer, a silver layer, and a tin layer, or sequentially stacked by a silver layer, a tin layer, and a silver layer. In another embodiment, the core metal 25b has a five-layer structure, sequentially stacked by a silver layer, a tin layer, a silver layer, a tin layer, and a silver layer, or sequentially stacked by a tin layer, a silver layer, a tin layer, a silver layer, and a tin layer. The electrode assembly includes a first electrode 22a, a second electrode 22b, a third electrode 22c, a fourth electrode 22d, and an auxiliary electrode 22e. The first, second, third, and fourth electrodes 22a, 22b, 22c, and 22d are printed on a substrate 21. The auxiliary electrode 22e extends perpendicularly to the third electrode 22c along the z-axis and then extends parallel to the substrate 21 along the x-axis toward the right in a top view. The first electrode 22a is electrically connected to the power input, while the second electrode 22b is electrically connected to the power output. The fuse 25 is not attached to the substrate 21 and spans the first and second electrodes 22a, 22b, thereby being connected in series with the electronic product (e.g., a battery) to be protected. When excessive current or excessive temperature flows through it, the fuse 25 will overheat and melt, preventing the battery from exploding during charging and discharging. Furthermore, to further enhance the performance of the fuse 25, a heater 23 is provided below it to actively melt the fuse 25. More specifically, the heating element 23 is disposed on the substrate 21 and connected to the third electrode 22c and the fourth electrode 22d. The fuse 25 and the heating element 23 are electrically connected to a switch and a detection element (not shown). When the detection element measures an overvoltage, the switch is switched to make the heating element 23 electrically conductive. Current flows through the heating element 23, causing the heating element 23 to generate heat and melt the fuse 25. The heating element 23 includes ruthenium oxide, nickel-chromium alloy, lead-germanium alloy, silicon-germanium alloy, or a combination thereof. In addition, the auxiliary electrode 22e directly contacts the fuse 25, which helps to transfer the heat generated by the heating element 23 and absorb the molten fuse 25. An insulating layer 24 is also included between the auxiliary electrode 22e and the heating element 23. The insulating layer 24 covers the heating element 23 and extends in the direction of the first electrode 22a and the second electrode 22b (i.e., the y-axis) to exceed the heating element 23, and finally adheres to the substrate 21. The insulating layer 24 comprises glass, glass ceramic, aluminum oxide, silicon carbide, magnesium silicon nitride or a combination thereof. Figure 3In the middle, the solid line is used to show the exposed portion when viewed from above, while the dotted line is used to show the covered portion when viewed from above. It can be seen that in the middle of the top view, the protection element 20 comprises the fuse link 25, the auxiliary electrode 22e, the insulation layer 24 and the heating element 23 stacked in order from top to bottom.

[0072] It should be noted that, by laser drilling or punching, the present application partially removes the fuse link 25 above the auxiliary electrode 22e, thereby forming a hollow portion H. The hollow portion H is located in the middle of the fuse link 25, completely overlaps the auxiliary electrode 22e (i.e. its directly below does not correspond to the edge of the auxiliary electrode 22e) when viewed from above, and exposes the bottom metal layer 25a above the auxiliary electrode 22e. The bottom metal layer 25a can be tin, tin-silver-copper alloy, tin-silver-lead alloy, tin-bismuth alloy or a combination thereof. The overlapping area O of the core metal layer 25b and the area of the bottom metal layer 25a on the auxiliary electrode 22e (see Figure 5a and Figure 5b , which will be described in more detail below) can be adjusted independently of each other. In addition, the bottom metal layer 25a is located at the lowermost part of the fuse link 25, which should be covered when viewed from above and is not shown in the top view. However, in order to clearly show the distribution area of the bottom metal layer 25a, it is shown as a solid block. As Figure 3 shown, the fuse link 25 can optionally add a bottom metal layer 25a at both ends (i.e. corresponding to the first electrode 22a and the second electrode 22b) in addition to the middle section (i.e. corresponding to the auxiliary electrode 22e).

[0073] For a clearer illustration of the structural design of the fuse link 25, please continue to refer to Figure 4 . Figure 4 It is shown that Figure 3Figure 6 is a cross-sectional view of the protection element 20 along the AA line segment. The protection element 20 comprises a fuse element 25, an electrode set, and a heating element 23. In addition to the aforementioned improved core metal layer 25b and bottom metal layer 25a, the fuse element 25 can optionally be provided with a top low-melting material layer 25c. The top low-melting material layer 25c comprises rosin resin, surfactant, thickening agent, and / or solvent. The bottom metal layer 25a is disposed below the core metal layer 25b, and the top low-melting material layer 25c is disposed above the core metal layer 25b. The melting point of the bottom metal layer 25a and the melting point of the top low-melting material layer 25c are both lower than the melting point of the core metal layer 25b. At high temperatures, the bottom metal layer 25a can form a eutectic alloy with the core metal layer 25b. The melting point of this eutectic alloy is lower than the melting point of the core metal layer 25b, thereby accelerating the melting rate of the fuse element 25. In the cross-sectional view, the electrode set has a first electrode 22a, a second electrode 22b, and an auxiliary electrode 22e. The two ends of the fuse element 25 are connected to the first electrode 22a and the second electrode 22b, respectively, and the auxiliary electrode 22e is located between the first electrode 22a and the second electrode 22b and is disposed below the fuse element 25, thereby contacting the bottom metal layer 25a. The fuse element 25 has a hollow portion H that penetrates through the top low-melting material layer 25c and the core metal layer 25b, thereby exposing the bottom metal layer 25a on the auxiliary electrode 22e. The heating element 23 is disposed below the auxiliary electrode 22e, thereby warming up and causing the fuse element 25 to melt when an overvoltage occurs. It should be noted that an insulating layer 24 is provided between the heating element 23 and the auxiliary electrode 22e. From the perspective of the cross-sectional view, the insulating layer 24 completely covers the heating element 23 and extends to the substrate 21, and is located substantially in the middle of the bottom metal layer 25a. The fuse element 25 is not in contact with the insulating layer 24, that is, there is a gap between the core metal layer 25b and the bottom metal layer 25a and the insulating layer 24. The heat conduction ability of the insulating layer 24 is better than that of air. In this way, the heat energy generated by the heating element 23 can be more concentratedly transmitted upward to the bottom metal layer 25a, thereby accelerating the melting rate. In addition, in order to improve the melting rate, the bottom metal layer 25a can also be correspondingly provided on the first electrode 22a and the second electrode 22b. That is, the fuse element 25 is divided into three endpoints, the leftmost endpoint is a first endpoint P1, the middle endpoint is a middle point P2, and the rightmost endpoint is a second endpoint P3. The bottom metal layer 25a of the fuse element 25 discontinuously extends along the y-axis from the first endpoint P1 to the second endpoint P3, and the bottom metal layer 25a is divided into at least three parts and is independently provided above the second electrode 22b, the auxiliary electrode 22e, and the first electrode 22a, respectively.

[0074] Please refer back to Figure 3 and Figure 5aThe present application adjusts the overlapping area O of the core metal layer 25b and the auxiliary electrode 22e, and the covering area of the bottom metal layer 25a on the auxiliary electrode 22e, to accelerate the fusing of the fuse member 25. The details are described as follows.

[0075] The overlapping area of the core metal layer 25b and the auxiliary electrode 22e in the top view has an overlapping area O. The hollow portion H has a first top view area in the top view. In more detail, the portion of the core metal layer 25b that does not penetrate has an overlapping area with the auxiliary electrode 22e in the top view, which is the overlapping area of the core metal layer 25b on the auxiliary electrode 22e, and has an overlapping area O; and the core metal layer 25b can project the pattern of the hollow portion (i.e. the hollow portion H) on the bottom metal layer 25a, so the projected area of the hollow portion H is the aforementioned first top view area. The sum of the overlapping area O and the first top view area is the overlapping area of the core metal layer 25b and the auxiliary electrode 22e before the core metal layer 25b penetrates. In the present application, the overlapping area O is 10% to 83% based on the sum of the overlapping area O and the first top view area being 100%. The mass of the core metal layer 25b of the present application becomes smaller relative to the complete core metal layer 25b. In the case of the same heat, the mass and the temperature change inversely. The smaller mass means faster heating, so the same heat can make the core metal layer 25b heat up faster and thus fuse faster. In addition, in the x-axis direction, the lateral length of the core metal layer 25b becomes extremely short, that is, the linear distance required for the core metal layer 25b to fuse becomes extremely short, which also helps to shorten the fusing time. In some cases, the hollow portion H of the core metal layer 25b provides a certain reserved space to prevent the fuse member 25 from deforming excessively due to high temperature during assembly, thereby improving the yield of component assembly. It should be noted again that based on the aforementioned hollow portion H, the proportion of the overlapping area O needs to be adjusted in the specific range mentioned above. When the overlapping area O is greater than 83%, the protection element 20 does not have significant improvement in fusing time and assembly yield, and only increases the burden on the process. When the overlapping area is less than 10%, the core metal layer 25b above the auxiliary electrode 22e is removed too much, which is easy to cause breakage during assembly. In an embodiment, the aforementioned overlapping area can be 10% to 78%, 15% to 83%, 10% to 45%, 15% to 78%, 45% to 83%, 10% to 15%, 15% to 45%, 45% to 78%, or 78% to 83%.

[0076] The bottom metal layer 25a has a specific coverage area on the auxiliary electrode 22e. More specifically, the bottom metal layer 25a on the auxiliary electrode 22e has a second top view area; and the second top view area of the bottom metal layer 25a is 50% to 90% based on the total of the overlap area O and the first top view area being 100%. The melting point of the bottom metal layer 25a is lower than that of the core metal layer 25b. Therefore, the eutectic alloy formed by the bottom metal layer 25a and the core metal layer 25b at high temperature can accelerate the fusing process of the core metal layer 25b. The second top view area of the bottom metal layer 25a must be controlled within the specific range as mentioned above. If the second top view area is greater than 90%, the amount of molten metal generated when the protection element 10 is activated will be excessive. This can cause the fusing member 25 to fail to completely disconnect, or increase the probability of the disconnected portion reconnecting after cooling. In addition, the excess molten metal can also flow to other electrodes, resulting in an increased possibility of short circuit. If the second top view area is less than 50%, the amount of eutectic alloy generated will be too small, resulting in poor fusing of the core metal layer 25b with a higher melting point, or even failure to fuse. In an embodiment, based on the range of the overlap area O mentioned above, the second top view area can correspond to 50% to 80%, 50% to 70%, 50% to 60%, 60% to 90%, 60% to 80%, or 60% to 70%. In another embodiment, based on the range of the overlap area O mentioned above, the second top view area can correspond to 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%. The bottom metal layer 25a on the auxiliary electrode 22e can be a single rectangle or divided into multiple blocks (as will be described in more detail below) and adjusted in coverage area. Figures 8 to 10

[0077] Please continue to refer to Figure 5a and Figure 5b . The hollow portion H can pass through the core metal layer 25b, or pass through both the core metal layer 25b and the bottom metal layer 25a. In Figure 5a , the bottom metal layer 25a directly below the hollow portion H completely covers the auxiliary electrode 22e, without exposing the auxiliary electrode 22e. In Figure 5b , the bottom metal layer 25a directly below the hollow portion H partially covers the auxiliary electrode 22e, thereby exposing the auxiliary electrode 22e. In other words, the hollow portion H can pass through both the core metal layer 25b and the bottom metal layer 25a, thereby exposing the bottom metal layer 25a and the auxiliary electrode 22e. In Figure 5b , this structure design helps to increase the heating rate, while reducing the total amount of metal needed to be fused in the middle of the fusing member 25 compared to Figure 5a , further helping to fuse faster.

[0078] In addition, the size of the hollow portion H of the fusing member 25 needs to be adjusted within a specific range, as described below.​Figure 3 、 Figure 5a and Figure 5b In the above-mentioned embodiments, the fuse member extends from the first electrode 22a to the second electrode 22b in the first direction and has a first length Ll parallel to the first direction and a first width Wl parallel to the second direction. The first direction is substantially parallel to the y-axis, and the second direction is substantially parallel to the x-axis, so the first direction is perpendicular to the second direction. The auxiliary electrode 22e extends from one side (e.g., the first long side S1 in the following Figures 8 to 10 ) of the fuse member 25 to the other side (e.g., the second long side S2 in the following Figures 8 to 10 ) of the fuse member 25 in the second direction in a top view and has an electrode width W3 parallel to the first direction, so the fuse member 25 and the auxiliary electrode 22e are arranged in a cross shape to form an overlapping region. The hollow portion H is located in the overlapping region and has a second length L2 parallel to the second direction (or the x-axis) and a second width W2 parallel to the first direction (or the y-axis). The ratio of the second length L2 of the hollow portion H to the first width Wl of the fuse member 25 is less than 0.9, and the second width W2 of the hollow portion H is less than the electrode width W3 of the auxiliary electrode 22e. If the size of the hollow portion H is too large, the fuse member 25 is adversely affected in assembly. If the ratio of the second length L2 to the first width Wl is equal to or greater than 0.9, the fuse member 25 on both sides of the hollow portion H (i.e., along the x-axis) is too long and thin, and is easily broken when assembled to the substrate 21. If the second width W2 of the hollow portion H is equal to or greater than the electrode width W3 of the auxiliary electrode 22e, the auxiliary electrode 22e does not support the hollow portion H directly below it along the y-axis (see Figure 4 ), and the chance of excessive deformation or breakage is also increased. For example, in one embodiment, the first length Ll and the first width Wl of the fuse member 25 are 3.5 mm and 3.5 mm, respectively, and the electrode width W3 of the auxiliary electrode 22e is 1.44 mm. Accordingly, the second length L2 of the hollow portion H is preferably less than 3.15 mm, and the second width W2 of the hollow portion H is preferably less than 1.44 mm. In another embodiment, the first length Ll and the first width Wl of the fuse member 25 can be 4 mm and 3 mm, 5.4 mm and 3.2 mm, or 9.5 mm and 5 mm, and the electrode width W3 of the auxiliary electrode 22e is adjusted in the range of 1 mm to 2 mm. Similarly, the second length L2 and the second width W2 of the hollow portion H are adjusted accordingly as described above.

[0079] Please continue to refer to Figure 6 and Figure 7 The hollow portion H can have different shapes. Figure 6 and Figure 7 and Figure 3Only the shape of the hollow portion H is different, the rest of the core metal layer 25b, the bottom metal layer 25a and the other elements can be designed the same as the foregoing, and will not be described again. More specifically, Figure 3 the hollow portion H is substantially rectangular, while Figure 6 the hollow portion H is substantially cruciform, and Figure 7 the hollow portion H is substantially diamond-shaped. In addition, the hollow portion H of different shapes also has a better range in size, which is specifically described as follows.

[0080] In Figure 6 , the hollow portion H is cruciform in plan view, and is substantially composed of two rectangular grooves (for example, two Figure 3 indicated hollow portion H) intersecting each other, one of which is parallel to the x-axis and the other is parallel to the y-axis. Each rectangle has the same length and width. For example, the rectangle parallel to the x-axis has a second length L2 parallel to the foregoing second direction and a second width W2 parallel to the foregoing first direction. Similarly, the ratio of the second length L2 of the hollow portion H to the first width W1 of the fuse 25 is less than 0.9, and the second width W2 of the hollow portion H is less than the electrode width W3 of the auxiliary electrode 22e. The reasons are the same as above, and will not be described again.

[0081] In Figure 7 , the hollow portion H is diamond-shaped in plan view, and has a diagonal line parallel to the x-axis. This diagonal line has a third length L3, which can correspond to the foregoing second length L2. Similarly, the ratio of the third length L3 of the hollow portion H to the first width W1 of the fuse 25 is less than 0.9. The reasons are the same as above, and will not be described again. In addition, the diamond-shaped hollow portion H is tapered at both ends along the y-axis direction, and has no problem of the foregoing support.

[0082] Please continue to refer to Figures 8 to 10 , the bottom metal layer 25a on the auxiliary electrode 22e can have different configurations. Specifically, the core metal layer 25b of the fuse 25 is not penetrated, and only the distribution area of the bottom metal layer 25a is simply adjusted. The core metal layer 25b and the auxiliary electrode 22e have an overlapping area in plan view, and the core metal layer 25b in the overlapping area has no hollow portion H. The bottom metal layer 25a on the auxiliary electrode 22e can be divided into multiple blocks in plan view, and the plan area thereof is less than the plan area of the overlapping area. Taking the plan area of the overlapping area as 100%, the plan area of the bottom metal layer 25a on the auxiliary electrode 22e is 30% to 79%. In addition, the shortest distance between any two adjacent blocks is at least 0.1mm. Details are described as follows.

[0083] In Figure 8In the embodiment, the bottom metal layer 25a is divided into a first block a1 and a second block a2, and the fuse link 25 has a first long side S1 and a second long side S2 opposite to the first long side S1 in plan view. The first long side S1 and the second long side S2 both extend parallel to the y-axis from the first electrode 22a to the second electrode 22b, and each has the first length L1 (not shown) as mentioned above. The first block a1 and the second block a2 both extend from the first long side S1 to the second long side S2, and have a shortest distance d of at least 0.1 mm between the first block a1 and the second block a2. The shortest distance d between the blocks prevents the bottom metal layer 25a from being excessive and causing problems such as failure to fuse. The shortest distance d forms a groove between the blocks on the auxiliary electrode 22e, allowing the excessive bottom metal layer 25a to flow in. In this way, the bottom metal layer 25a does not accumulate at the breaking point when the protection element 20 is activated, so that the fusing time is shortened and the possibility of intermetallic reconnection is reduced. In addition, if the fuse link 25 encounters an unexpected high temperature after being assembled to the substrate 21, the groove formed by the shortest distance d also prevents the bottom metal layer 25a from overflowing outward excessively.

[0084] In the embodiment, Figure 9 , the fuse link 25 has a first long side S1 and a second long side S2 opposite to the first long side S1 in plan view, and the bottom metal layer 25a discontinuously extends along the x-axis from the first long side S1 to the second long side S2, thereby being divided into a first block b1, a second block b2, and a third block b3. The first block b1 overlaps the first long side S1, the third block b3 overlaps the second long side S2, and the second block b2 is located between the first block b1 and the third block b3. Similarly, any two adjacent ones of these blocks have a shortest distance d of at least 0.1 mm between them.

[0085] In the embodiment, Figure 10 , the bottom metal layer 25a is divided into a first block c1, a second block c2, a third block c3, and a fourth block c4, and the fuse link 25 has a first long side S1 and a second long side S2 opposite to the first long side S1 in plan view. These blocks (i.e., the first block c1, the second block c2, the third block c3, and the fourth block c4) do not overlap the first long side S1 and the second long side S2, and do not extend to the edges of the auxiliary electrode 22e. Similarly, any two adjacent ones of these blocks have a shortest distance d of at least 0.1 mm between them.

[0086] It should be noted again that the design of the above-mentioned Figures 8 to 10 can also be combined with the hollow portion H of Figures 3 to 7 . For example, the bottom metal layer 25a in Figure 3 may be designed as the bottom metal layer 25a of Figure 8 , Figure 9 or Figure 10 . Figures 4 to 7The bottom metal layer 25a can be transformed in the same way. To avoid redundancy, the remaining details are discussed above and will not be repeated here.

[0087] Furthermore, to make the core metal layer 25b overlap area and the bottom metal layer 25a coverage area discussed above more clear, the following verification is made.

[0088] Table 1

[0089]

[0090]

[0091] In Table 1, Group C1 is Comparative Example C1, and Groups E1 to E10 are Inventive Examples E1 to E10.

[0092] Comparative Example C1 can refer to Figure 1 and Figure 2 protective element 10. The length of the fuse link 15 is 3.5 mm, and the width is 3.5 mm. The width of the auxiliary electrode 12e is 1.44 mm. In the fuse link 15, the thickness of the core metal layer 15b is 0.025 mm, and the thickness of the bottom metal layer 15a is 0.2 mm. The fuse link 15 extends along the y-axis, and the auxiliary electrode 12e extends along the x-axis, and they are arranged to cross each other in plan view and have an overlap area. The plan view area of the core metal layer 15b is the same as the plan view area of the overlap area. That is, the overlap area of the core metal layer 15b is 100% based on the plan view area of the overlap area. In addition, the coverage area of the bottom metal layer 15a on the auxiliary electrode 12e is 80% based on the plan view area of the overlap area. When the protective element 10 is passed through a power of 43 watts (W), the fuse link 15 will be fused at 2.68 seconds (s).

[0093] Inventive Examples E1 to E3 can refer to Figure 3 and Figure 4The differences between Examples El to E3 and Comparative Example Cl are only in the hollow portion H. In addition, in practical applications, the thickness of the core metal layer 25b can be adjusted within a range between 0.01 mm and 0.3 mm, and the thickness of the bottom metal layer 25a can be adjusted within a range between 0.1 mm and 1 mm. The sum of the overlapping area O of the core metal layer 25b and the projected area of the hollow portion H is equivalent to the top view area of the overlapping region of the fuse link 15. In Examples El to E3, the overlapping area O of the core metal layer 25b is 15% to 78% based on the sum of the overlapping area O of the core metal layer 25b and the projected area of the hollow portion H being 100%. By penetrating the core metal layer 25b, the melting time of the fuse link 25 can be reduced to 2.1 seconds to 2.26 seconds. The proportion of the melting time being faster is 15.67% to 21.64% based on 2.68 seconds. It should be noted that if the overlapping area O of the core metal layer 25b is less than 15% too much, the core metal layer 25b above the auxiliary electrode 22e will be removed too much, which is easy to cause breakage during assembly. Considering the influence of errors and the allowable variation range, the overlapping area O of the core metal layer 25b can be adjusted within a range between 10% and 83%. Based on the presence of the hollow portion H, the proportion range of the coverage area of the bottom metal layer 25a can also be adjusted within a range between 50% and 90%. In addition, as mentioned above, while adjusting the overlapping area O, the relative sizes of the hollow portion H and other components must also be considered to avoid affecting the assembly yield.

[0094] Examples E4 to E10 and Comparative Example Cl are all without the hollow portion H, and the difference between them is only in the coverage area of the bottom metal layer on the auxiliary electrode. As mentioned above, Examples E4 to E10 can also be designed as Figures 8 to 10 In Examples E4 to E10, the coverage area of the bottom metal layer 25a on the auxiliary electrode 22e is 20% to 100% based on the top view area of the overlapping region being 100%. As can be seen from Table 2, as the coverage area of the bottom metal layer 25a decreases to 35% to 78%, the proportion of the melting time being faster is 3.54% to 30.04%. It should be noted that the coverage area of the bottom metal layer 25a being too large or too small will cause the fuse link 25 to be unable to melt. When the coverage area of the bottom metal layer 25a is 100%, the auxiliary electrode 22e in the overlapping region will be completely covered with the bottom metal layer 25a, so that the amount of molten metal at the breaking point is too large, thereby being unable to melt. When the coverage area of the bottom metal layer 25a is 20%, the amount of eutectic alloy generated will be too small, causing the core metal layer 25b with a higher melting point to be unable to melt. Considering the influence of errors and the allowable variation range, the coverage area of the bottom metal layer 25a can be adjusted within a range between 30% and 79%.

[0095] The technical contents and features of the present application have been disclosed above, however, those skilled in the art can make various replacements and modifications based on the inspiration and disclosure of the present application without departing from the concept of the present application. Therefore, the protection scope of the present application should not be limited to the disclosed embodiments, but should include various replacements and modifications without departing from the present application, and is covered by the following claims.

Claims

1. A protection element comprising: A fuse element having a core metal layer and a bottom metal layer disposed below the core metal layer, wherein the bottom metal layer has a melting point lower than that of the core metal layer; An electrode set comprises a first electrode, a second electrode and an auxiliary electrode, wherein: Two ends of the fuse are connected to the first electrode and the second electrode respectively, and the auxiliary electrode is located between the first electrode and the second electrode and is disposed below the fuse so as to contact the bottom metal layer; as well as The fuse has a hollow portion penetrating the core metal layer, thereby exposing the bottom metal layer on the auxiliary electrode; as well as A heating element is arranged below the auxiliary electrode, so as to increase the temperature and cause the fuse to melt when an overvoltage occurs.

2. The protection element according to claim 1, wherein: The core metal layer and the auxiliary electrode have an overlapping area in an overlapping region when viewed from above; The hollow portion has a first top-view area in a top-view; and Taking the sum of the overlapping area and the first top-view area as 100%, the overlapping area is 10% to 83%. The protection device according to claim 2 , wherein the hollow portion completely overlaps the auxiliary electrode in a plan view.

4. The protection element according to claim 2, wherein: The bottom metal layer on the auxiliary electrode has a second top-view area in a top view; and Taking the sum of the overlapping area and the first top-view area as 100%, the second top-view area of ​​the bottom metal layer is 50% to 90%.

5. The protection element according to claim 1, wherein: The fuse extends from the first electrode to the second electrode along a first direction and has a first length parallel to the first direction and a first width parallel to a second direction, wherein the first direction is perpendicular to the second direction; The auxiliary electrode extends from one side of the fuse element to the other side of the fuse element along the second direction in a top view, and has an electrode width parallel to the first direction, whereby the fuse element and the auxiliary electrode are intersected to form an overlapping area; The hollow portion is located in the overlapping area and has a second length parallel to the second direction and a second width parallel to the first direction; and A ratio of the second length of the hollow portion divided by the first width of the fuse is less than 0.9, and the second width of the hollow portion is less than the electrode width of the auxiliary electrode. The protection element according to claim 1 , wherein the hollow portion has a rectangular, cross, or diamond shape in a top view. 7 . The protection device according to claim 1 , wherein the bottom metal layer on the auxiliary electrode is divided into a plurality of blocks in a top view. 8 . The protection element according to claim 7 , wherein a shortest distance between any two adjacent blocks is at least 0.1 mm. 9 . The protection element according to claim 1 , wherein the core metal layer has a thickness of 0.01 mm to 0.3 mm. 10 . The protection device according to claim 1 , wherein the bottom metal layer has a thickness of 0.1 mm to 1 mm. 11 . The protection device according to claim 1 , wherein the core metal layer is composed of a single layer, wherein the core metal layer is a tin-silver-lead alloy, a tin-silver-copper alloy, a tin-silver-bismuth alloy, or a tin-zinc alloy.

12. The protection device according to claim 1, wherein the core metal layer is composed of a plurality of metal layers, wherein the core metal layer is a three-layer structure, which is sequentially stacked by a tin layer, a silver layer, and a tin layer, or sequentially stacked by a silver layer, a tin layer, and a silver layer.

13. The protection device according to claim 1 , wherein the core metal layer is composed of a plurality of metal layers, wherein the core metal layer has a five-layer structure, which is sequentially stacked by a silver layer, a tin layer, a silver layer, a tin layer, and a silver layer, or sequentially stacked by a tin layer, a silver layer, a tin layer, a silver layer, and a tin layer. 14 . The protection device according to claim 1 , wherein the bottom metal layer comprises tin, tin-silver-copper alloy, tin-silver-lead alloy, tin-bismuth alloy, or a combination thereof. 15 . The protection device according to claim 1 , wherein the heating element comprises ruthenium oxide, nickel-chromium alloy, lead-germanium alloy, silicon-germanium alloy, or a combination thereof. 16 . The protection device according to claim 1 , further comprising a substrate and an insulating layer, wherein the heating element is disposed on the substrate, and the insulating layer is disposed between the auxiliary electrode and the heating element and extends to the substrate. 17 . The protection device according to claim 16 , wherein the insulating layer comprises glass, glass ceramic, aluminum oxide, silicon carbide, magnesium silicon nitride, or a combination thereof.

18. A protection element comprising: A fuse element having a core metal layer and a bottom metal layer disposed below the core metal layer, wherein the bottom metal layer has a melting point lower than that of the core metal layer; An electrode set comprises a first electrode, a second electrode and an auxiliary electrode, wherein: Two ends of the fuse are connected to the first electrode and the second electrode respectively, and the auxiliary electrode is located between the first electrode and the second electrode and is disposed below the fuse so as to contact the bottom metal layer; The core metal layer and the auxiliary electrode have an overlapping area in a top view, and the core metal layer in the overlapping area has no hollow portion; and The top-view area of ​​the bottom metal layer on the auxiliary electrode is smaller than the top-view area of ​​the overlapping region; as well as A heating element is arranged below the auxiliary electrode, so as to increase the temperature and cause the fuse to melt when an overvoltage occurs. 19 . The protection device according to claim 18 , wherein based on a top-view area of ​​the overlapping region being 100%, a top-view area of ​​the bottom metal layer on the auxiliary electrode is 30% to 79%. 20 . The protection device according to claim 18 , wherein the bottom metal layer on the auxiliary electrode consists of a plurality of blocks in a top view.

21. The protection element according to claim 20, wherein the multiple blocks of the bottom metal layer are a first block and a second block, and the fuse has a first long side and a second long side opposite to the first long side when viewed from above, wherein the first block and the second block both extend from the first long side to the second long side, and the shortest distance between the first block and the second block is at least 0.1 mm.

22. The protection element according to claim 20, wherein the fuse has a first long side and a second long side opposite to the first long side in a top view, and the bottom metal layer extends discontinuously from the first long side to the second long side, thereby being divided into the multiple blocks of a first block, a second block and a third block, wherein the first block overlaps the first long side, the third block overlaps the second long side, and the second block is located between the first block and the third block, wherein the shortest distance between any two adjacent ones of the multiple blocks is at least 0.1 mm.

23. The protection element according to claim 20, wherein the multiple blocks of the bottom metal layer are a first block, a second block, a third block and a fourth block, and the fuse has a first long side and a second long side opposite to the first long side when viewed from above, wherein the multiple blocks do not overlap with the first long side and the second long side, and the multiple blocks do not extend to the edge of the auxiliary electrode, wherein the shortest distance between any two adjacent ones of the multiple blocks is at least 0.1 mm.

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