Lead-free fuse device with reactive metal foil

Abstract

A lead-free fuse device is provided in which an electrical joint between an element in the fuse device and a terminal in the fuse device may be formed using a reactive metal foil disposed between the element and the terminal. The fuse device may include a body, an element received within the body, a first end of the element extending to an exterior of a first end of the body, a terminal disposed at the first end of the body, and a metal foil disposed between the element and an inner surface of the terminal. When the metal foil is activated by an external energy pulse, the metal foil may release heat that raises the temperature within a localized region of the metal foil, thereby fusing the metal foil with the inner surfaces of the element and the terminal to form an electrical joint.

Description

Technical Field

[0001] The present disclosure relates generally to fuse devices. More particularly, the present disclosure relates to lead-free fuse devices having reactive metal foils. Background Art

[0002] Fuses are commonly used as circuit protection devices and can provide an electrical connection between a power source and a circuit component to be protected, such as in automotive and power distribution environments. Known fuses have a lead (Pb) portion that includes solder used to form an electrical connection therein. However, the Restriction of Hazardous Substances (RoHS) directives in some jurisdictions restrict the use of certain hazardous substances in electrical and electronic equipment. Lead is one such substance. Therefore, as the market complies with these RoHS directives, fuses must remain lead-free.

[0003] In view of the foregoing, there is a continuing, ongoing need for improved fuse devices. Summary of the invention

[0004] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This brief summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to assist in determining the scope of the claimed subject matter.

[0005] In some embodiments, the fuse device may include a body, an element housed in the body, wherein a first end of the element may extend outside the first end of the body, a terminal disposed at the first end of the body, and a metal foil disposed between an inner surface of the terminal and the element. When the metal foil is activated by an external energy pulse, the metal foil may release heat, which increases the temperature in a local area of ​​the metal foil, thereby fusing the metal foil to the inner surface of the terminal and the element to form an electrical joint.

[0006] In some embodiments, the external energy pulse may come from an electrical, thermal, or optical source.

[0007] In some embodiments, the metal foil may undergo an exothermic reaction to release heat.

[0008] In some embodiments, the element may be a wire or a microstrip.

[0009] In some embodiments, the terminal may be an end cap, a plated terminal, or a lead.

[0010] In some embodiments, the body may be one or two pieces.

[0011] In some embodiments, the metal foil may be activated indirectly by an external energy pulse through the terminals.

[0012] In some embodiments, the heat may melt the coating on the outer surface of the metal foil to produce solder for forming the electrical joint.

[0013] In some embodiments, the heat may melt a coating on an outer surface of the component to produce solder for forming an electrical joint.

[0014] In some embodiments, the heat may melt a coating on an outer surface of the terminal to produce solder for forming an electrical joint.

[0015] In some embodiments, a method may include disposing an element within a body, wherein a first end of the element may extend outside of the first end of the body, disposing a metal foil in a terminal, disposing the terminal at the first end of the body, wherein the metal foil is sandwiched between the element and an inner surface of the terminal, and activating the metal foil using an external energy pulse so that the metal foil releases heat, and the heat increases the temperature of a local area of ​​the metal foil, thereby causing the metal foil to fuse with the element and the inner surface of the terminal to form an electrical joint.

[0016] In some embodiments, the external energy pulse may come from an electrical, thermal, or optical source.

[0017] In some embodiments, the metal foil may undergo an exothermic reaction to release heat. Other technical features will be apparent to those skilled in the art from the following drawings, description and claims.

[0018] In some embodiments, the element may be a wire or a microstrip.

[0019] In some embodiments, the terminal may be an end cap, a plated terminal, or a lead.

[0020] In some embodiments, the body may be one or two pieces.

[0021] In some embodiments, the method may include indirectly activating the metal foil using an external energy pulse through the terminals.

[0022] In some embodiments, the heat may melt the coating on the outer surface of the metal foil to produce solder for forming the electrical joint.

[0023] In some embodiments, the heat may melt a coating on an outer surface of the component to produce solder for forming an electrical joint.

[0024] In some embodiments, the heat may melt a coating on an outer surface of the terminal to produce solder for forming an electrical joint.

[0025] Other technical features will be clear to those skilled in the art from the following drawings, description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A is an exploded view showing a fuse device according to an embodiment of the present disclosure.

[0027] Figure 1B is a cross-sectional view showing a fuse device according to an embodiment of the present disclosure.

[0028] Figure 2A is a perspective view showing a metal foil according to an embodiment of the present disclosure.

[0029] Figure 2B is a graph showing atomic diffusion versus thermal diffusion in a metal foil according to an embodiment of the present disclosure.

[0030] Figure 3 is a flow chart illustrating a method 300 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] Exemplary embodiments of lead-free fuse devices with reactive metal foils according to the present disclosure will now be described more fully below with reference to the accompanying drawings. However, the lead-free fuse devices with reactive metal foils can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Instead, these embodiments are provided so that the present disclosure will convey certain exemplary aspects of the lead-free fuse devices with reactive metal foils to those skilled in the art.

[0032] According to disclosed embodiments, an electrical connection between an element in a fuse device and a terminal in the fuse device can be formed using a reactive metal foil disposed between the element and the terminal. In particular, when the reactive metal foil is activated or ignited by an external energy pulse, the reactive metal foil can release heat that raises the temperature in a local area of ​​the metal foil, which can cause the metal foil to fuse with the inner surface of the element and the terminal to form an electrical connection. In some embodiments, the reactive metal foil can undergo a rapid exothermic reaction to release heat. Advantageously, in some embodiments, the heat can raise the temperature in a local area of ​​the metal foil to approximately 1500° C. within a few milliseconds of being activated or ignited.

[0033] In some embodiments, the external energy pulse can come from a power source, a heat source, or a light source. In this regard, in some embodiments, the metal foil can be indirectly activated by the external energy pulse through the terminal. For example, in some embodiments, the external energy pulse can be applied to the outer surface of the terminal with minimal pressure, and the terminal can transfer this energy to the reactive metal foil.

[0034] In some embodiments, the reactive metal foil may include a metal foil composed of alternating nanoscale multiple layers of a first metal and a second metal with a mixed region between the first metal and the second metal. For example, in some embodiments, the first metal may be aluminum (Al) and the second metal may be nickel (Ni). However, the embodiments disclosed herein are not limited thereto and may include other metals as would be appreciated by one of ordinary skill in the art. In some embodiments, the reactive metal foil may include NanoFoil from Indium Corporation.

[0035] The heat generated and released by the reactive metal foil can be used as a fusion mechanism to join metal objects in a fuse device. For example, in some embodiments, the heat can melt the coating on the outer surface of the reactive metal foil to produce solder for forming an electrical joint. Additionally or alternatively, in some embodiments, the heat can melt the coating on the outer surface of the element to produce solder for forming an electrical joint. Additionally or alternatively, in some embodiments, the heat can melt the coating on the outer surface of the terminal to produce solder for forming an electrical joint. In some embodiments, the coating on the outer surface of the reactive metal foil, the element and / or the terminal may include tin, silver, etc. However, as will be understood by those of ordinary skill in the art, the disclosed embodiments are not limited thereto and may be compatible with any coating or plating on the components of the fuse device to produce solder.

[0036] Advantageously, the fuse devices disclosed herein can be lead-free, thereby eliminating the need for external lead solder to join any metal objects together. In this regard, the fuse device can be environmentally friendly and comply with the RoHS directive that restricts the use of lead in electrical and electronic equipment. In addition, because the solder used to form the electrical joints as disclosed herein can be directly produced from the reactive metal foil, components or terminals, soldering can be nearly instantaneous and occur at room temperature. Still further, forming electrical joints in this manner can be flux-free and eliminate any need to expose components of the fuse device to reflow temperatures, thereby protecting all components of the fuse device from thermal damage. Still further, the electrical joints formed as described herein can exhibit an improved thermal resistance drop over conventional and known thermal interface materials while still achieving the desired fuse rating, resistance, and I 2 t capability and remains stable throughout the life test. In fact, the I 2 t capability can be superior to electrical joints formed with conventional and known thermal interface materials, at least because the embodiments disclosed herein can eliminate high brazing (Pb) solder ridges that are characteristic of electrical joints formed with conventional and known thermal interface materials, thereby achieving an effectively longer fuse element length.

[0037] It should be understood that the electrical connections between the elements and the terminals can be formed as disclosed and described herein in conjunction with any type of fuse device, as understood by a person of ordinary skill in the art. For example, in some embodiments, the elements in the fuse device can include wires. Additionally or alternatively, in some embodiments, the elements in the fuse device can include microstrips. Further, in some embodiments, the terminals in the fuse device can include covers, such as end caps that can be assembled on the ends of the body of the fuse device. Additionally or alternatively, in some embodiments, the terminals can include plated terminals. Additionally or alternatively, in some embodiments, the terminals can include leads. Further, in some embodiments, the body can be one workpiece or two workpieces.

[0038] Figure 1A is an exploded view showing a fuse device 100 according to an embodiment of the present disclosure, and Figure 1B is a cross-sectional view showing a fuse device 100. As shown, the fuse device 100 may include a body 102 and an element 104 that may be accommodated within the body 102. A first end of the element 104 may extend outside the first end of the body 102, and a second end of the element 104 may extend outside the second end of the body 102. The fuse device 100 may also include a first terminal 106 disposed at the first end of the body 102 and a second terminal 106 disposed at the second end of the body. Finally, the fuse device 100 may include a first metal foil 108 disposed between the element 104 and the first terminal 106 and a second metal foil 108 disposed between the element 104 and the second terminal 106. In particular, in some embodiments, the first metal foil 108 may be hidden below or inside the first terminal 106 and sandwiched between the inner surface of the first terminal 106 and the element 104. Similarly, in some embodiments, the second metal foil 108 may be hidden beneath or within the second terminal 106 and sandwiched between the inner surface of the second terminal 106 and the element 104 .

[0039] In some embodiments, the first metal foil 108 may be activated or ignited by an external energy pulse, and in response thereto, the first metal foil 108 may release heat, which heat increases the temperature in a local area of ​​the first metal foil 108, thereby causing the first metal foil 108 to fuse with the inner surface of the element 104 and the first terminal 106 to form a first electrical connection. Similarly, in some embodiments, the second metal foil 108 may be activated or ignited by an external energy pulse, and in response thereto, the second metal foil 108 may release heat, which heat increases the temperature in a local area of ​​the second metal foil 108, thereby causing the second metal foil 108 to fuse with the inner surface of the element 104 and the second terminal 106 to form a second electrical connection.

[0040] In this regard, the heat generated and released by the first metal foil 108 and / or the second metal foil 108 can be used as a welding mechanism to join the metal objects in the fuse device 100. For example, in some embodiments, the heat can melt the coating on the outer surface of the first metal foil 108 to produce solder for forming the first electrical connection, and / or the heat can melt the coating on the outer surface of the second metal foil 108 to produce solder for forming the second electrical connection. Additionally or alternatively, in some embodiments, the heat can melt the coating on the outer surface of the element 104 to produce solder for forming the first electrical connection and / or the second electrical connection. Additionally or alternatively, in some embodiments, the heat can melt the coating on the outer surface of the first terminal 106 to produce solder for forming the first electrical connection, and / or the heat can melt the coating on the outer surface of the second terminal 106 to produce solder for forming the second electrical connection.

[0041] In some embodiments, the external energy pulse can come from a power source, a heat source, or a light source. Figure 1B As best shown, in some embodiments, one or more welding probes 110 can be placed on the outer surface of the first terminal 106 to apply an external energy pulse to the outer surface of the first terminal 106. In response, the first terminal 106 can transfer this energy to the first metal foil 108, thereby indirectly activating the first metal foil 108 through the first terminal 106 using the external energy pulse. Similarly, although in Figure 1B 106, but it should be understood that one or more welding probes may also be placed on the outer surface of the second terminal 106 to apply an external energy pulse to the outer surface of the second terminal 106. In response, the second terminal 106 may transfer such energy to the second metal foil 108, thereby indirectly activating the second metal foil 108 through the second terminal 106 using the external energy pulse.

[0042] It should be understood that the electrical connection between the element and the terminal can be formed as disclosed and described herein in conjunction with any type of fuse device, as understood by a person of ordinary skill in the art. For example, in some embodiments, the element 104 can include a wire. Additionally or alternatively, in some embodiments, the element 104 can include a microwave transmission strip. In addition, in some embodiments, the first terminal 106 and / or the second terminal 106 can include a cover on the body 102. Additionally or alternatively, in some embodiments, the first terminal 106 and / or the second terminal 106 can include a plated terminal. Additionally or alternatively, in some embodiments, the first terminal 106 and / or the second terminal 106 can include a lead. Further, in some embodiments, the body 102 can be one or two pieces.

[0043] Figure 2Ais a perspective view showing a metal foil 200 according to an embodiment of the present disclosure, and Figure 2B is a graph 210 illustrating atomic diffusion versus thermal diffusion in metal foil 200 . It should be appreciated that metal foil 200 may be the same as or similar to first metal foil 108 , second metal foil 108 , and / or metal foil 208 .

[0044] In an initial state as deposited and unreacted, the metal foil 200 may include alternating layers of a first metal and a second metal with mixed regions therebetween. For example, in some embodiments, the alternating layers may include alternating nanoscale multilayers of a first metal and a second metal with mixed regions therebetween. However, when activated or ignited by an external energy pulse, the metal foil 200 may undergo an exothermic reaction to release heat. During this reaction, atoms in the alternating layers of the first metal, the second metal, and the mixed regions may diffuse until a fully reacted second state is reached in which the atoms are fully diffused. For example, as Figure 2A and Figure 2B As shown, the diffusion of atoms in the metal foil 200 can be positively correlated with the thermal diffusion relative to the external energy pulse source ("ignition"). In particular, as heat propagates along the x-axis of the metal foil 200 from the point of ignition, the atoms in the metal foil 200 can diffuse to achieve the second state until all of the metal foil 200 has been transformed from the initial state to the second state.

[0045] Metal foils known in the prior art have been used to join metals with flat surfaces. Indeed, because metal foils known in the art are flat, they can be easily attached to other flat surfaces, for example, using a die attach process that directly exposes the metal foil to an energy source during activation or ignition. However, the metal foil 200 disclosed and described herein can be attached to both flat and non-flat surfaces, and can be used to connect non-flat surfaces (such as a cylindrical wire) to flat surfaces (such as the inner surface of an end cap), for example, by hiding the metal foil 200 below or inside the end cap and sandwiching the metal foil 200 between the inner surface of the end cap and the cylindrical wire, so that activation or ignition is initiated on the end cap instead of the external energy pulse source directly contacting the metal foil 200.

[0046] Figure 3 is a flow chart showing a method 300 according to an embodiment of the present disclosure. Figure 3 As shown, method 300 may include placing an element within a body, as in 302, wherein a first end of the element may extend outside of a first end of the body. In some embodiments, the element may include a wire or a microstrip, and in some embodiments, the body may be one or two pieces.

[0047] Method 300 may also include placing a metal foil in the terminal, as in 304, and placing the terminal at the first end of the body, as in 306, wherein the metal foil may be sandwiched between the element and the inner surface of the terminal. In some embodiments, the terminal may include an end cap, a plated terminal, or a lead.

[0048] Then, method 300 may include activating the metal foil with an external energy pulse, as in 308, so that the metal foil releases heat, which can increase the temperature in the local area of ​​the metal foil, so that the metal foil is welded to the inner surface of the component and the terminal to form the electrical joint. In some embodiments, method 300 may also include activating the metal foil indirectly through the terminal using the external energy pulse, and in some embodiments, the external energy pulse can come from a power source, a heat source, or a light source. In some embodiments, the metal foil can undergo an exothermic reaction to release heat, and in some embodiments, the heat can melt the coating on the outer surface of the metal foil, the component and / or the terminal to produce solder for forming the electrical joint.

[0049] As used herein, an element or step described in the singular and beginning with the word "a" or "an" should be understood as not excluding multiple elements or steps, unless such exclusion is explicitly stated. In addition, reference to "one embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional embodiments that also include the described features.

[0050] Although the present disclosure has been described with reference to certain embodiments, many modifications, variations and changes to the described embodiments may be made without departing from the field and scope of the present disclosure as defined in the appended claims. Therefore, the present disclosure is not limited to the described embodiments, but has the full scope defined by the language of the appended claims and their equivalents.

Claims

1. A fuse device, comprising: main body; an element housed within the body, wherein a first end of the element extends outside of the first end of the body; a terminal disposed at the first end of the body; as well as A metal foil disposed between the component and the inner surface of the terminal, When the metal foil is activated by an external energy pulse, the metal foil releases heat, which increases the temperature in a local area of ​​the metal foil, thereby causing the metal foil to fuse with the inner surface of the component and the terminal to form an electrical joint.

2. The fuse device according to claim 1, wherein: The external energy pulse comes from an electrical source, a heat source or a light source.

3. The fuse device according to claim 1, wherein: The metal foil undergoes an exothermic reaction to release heat.

4. The fuse device according to claim 1, wherein: The element is a wire or a microwave strip.

5. The fuse device according to claim 1, wherein: The terminals are end caps, plated terminals or leads.

6. The fuse device according to claim 1, wherein: The body is one workpiece or two workpieces.

7. The fuse device according to claim 1, wherein: The metal foil is activated indirectly by an external energy pulse through the terminals.

8. The fuse device according to claim 1, wherein: The heat melts the coating on the outer surface of the metal foil to produce solder for forming the electrical joint.

9. The fuse device according to claim 1, wherein: The heat melts the coating on the outer surface of the component to produce solder for forming the electrical joint.

10. The fuse device according to claim 1, wherein: The heat melts the coating on the outer surface of the terminal to produce solder for forming the electrical joint.

11. A method comprising: disposing an element within the body, wherein a first end of the element extends outside of the first end of the body; disposing the metal foil in the terminal; disposing the terminal at the first end of the body, wherein the metal foil is sandwiched between the element and an inner surface of the terminal; and The metal foil is activated by an external energy pulse, causing the metal foil to release heat, which increases the temperature in a local area of ​​the metal foil, causing the metal foil to fuse with the inner surface of the component and the terminal to form an electrical joint.

12. The method according to claim 11, wherein: The external energy pulse comes from an electrical source, a heat source or a light source.

13. The method according to claim 11, wherein: The metal foil undergoes an exothermic reaction to release heat.

14. The method according to claim 11, wherein: The element is a wire or a microwave strip.

15. The method according to claim 11, wherein: The terminals are end caps, plated terminals or leads.

16. The method according to claim 11, wherein: The body is one workpiece or two workpieces.

17. The method according to claim 11, further comprising: The metal foil is activated indirectly via the terminals using an external energy pulse.

18. The method according to claim 11, wherein: The heat melts the coating on the outer surface of the metal foil to produce solder for forming the electrical joint.

19. The method according to claim 11, wherein: The heat melts the coating on the outer surface of the component to produce solder for forming the electrical joint.

20. The method according to claim 11, wherein: The heat melts the coating on the outer surface of the terminal to produce solder for forming the electrical joint.

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