Ultrathin solderable fuse

Abstract

The application discloses an ultrathin solderable fuse. Various protection devices and related methods are disclosed. In some embodiments, the protection device may include a substrate and a fusible element extending between a first terminal and a second terminal, where the fusible element, the first terminal, and the second terminal are coupled to the substrate. The protection device may also include a cover formed over the fusible element, where the fusible element is positioned between the cover and the substrate.

Description

Technical Field

[0001] The present disclosure generally relates to the field of protection devices. More specifically, embodiments of the present disclosure relate to an ultra-thin solderable fuse. Background Art

[0002] Fuses are commonly used as circuit protection devices and form an electrical connection with components in the circuit to be protected. A pair of conductors or terminals are typically connected via a fusible element that forms a bridge between the terminals. However, some fuses take up too much space.

[0003] Therefore, there is a need for a thin fuse suitable for battery protection, wherein the desired electrical performance is still maintained. Summary of the invention

[0004] This summary is provided to introduce some concepts in a simplified form that are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter.

[0005] In one approach, a protection device may include a substrate and a fusible element extending between a first terminal and a second terminal, wherein the fusible element, the first terminal, and the second terminal are coupled to the substrate. The protection device may also include a cover formed on the fusible element, wherein the fusible element is positioned between the cover and the substrate.

[0006] In another approach, a method of forming a protection device may include coupling a fusible element to a substrate, wherein the fusible element extends between a first terminal and a second terminal, and forming a cover on the fusible element, wherein the fusible element is positioned between the cover and the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings illustrate exemplary methods of the disclosed embodiments hitherto devised for practical application of its principles, and in which:

[0008] Figure 1 depicts a perspective view of a protection device according to an embodiment of the present disclosure;

[0009] Figure 2 Describes an embodiment of the present disclosure Figure 1 An exploded perspective view of a protective device;

[0010] Figure 3 Describes an embodiment of the present disclosure Figure 1 Another perspective view of the protective device;

[0011] Figure 4 depicts a perspective view of a protection device according to an embodiment of the present disclosure;

[0012] Figure 5 Describes an embodiment of the present disclosure Figure 4 An exploded perspective view of a protective device;

[0013] Figure 6 Describes an embodiment of the present disclosure Figure 4 Another perspective view of the protective device;

[0014] Figure 7-8 Depicted is a circuit board including multiple plating layers according to an embodiment of the present disclosure Figure 4 A perspective view of a protective device;

[0015] Fig. 9 Describes the formation of an embodiment according to the present disclosure Figure 1-3 A flow chart of a method for protecting a device;

[0016] Fig.10 Describes the formation of an embodiment according to the present disclosure Figure 4-8 A flow chart of a method for protecting a device;

[0017] Figure 11-12 depicts a perspective view of a protection device according to an embodiment of the present disclosure; and

[0018] Fig.13 Describes an embodiment of the present disclosure Figure 11-12 An exploded perspective view of a protective device.

[0019] The accompanying drawings are not necessarily drawn to scale. The accompanying drawings are merely representations and are not intended to depict specific parameters of the present disclosure. The accompanying drawings are intended to depict exemplary embodiments of the present disclosure and therefore should not be considered to limit the scope. In the accompanying drawings, the same reference numerals represent the same elements.

[0020] In addition, for the sake of clarity, some elements in some of the drawings may be omitted or not shown to scale. For the sake of clarity, the cross-sectional views may be in the form of "sliced" or "close-up" cross-sectional views, omitting some background lines that would be visible in a "true" cross-sectional view. In addition, for the sake of clarity, some reference numerals may be omitted in some of the drawings. DETAILED DESCRIPTION

[0021] The protection device, fuse assembly and method according to the present disclosure will be described more fully below with reference to the accompanying drawings, in which embodiments are shown. The protection device, fuse assembly and method can be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0022] Embodiments of the present disclosure provide an ultra-thin solderable solution for battery protection applications using a flexible polyimide substrate material. The fuse is flexible and achieves an ultra-thin profile of less than about 0.4 mm. The electrical performance can be optimized by modifying the fusible element pattern extending between the terminals. In some examples, a polyamide (PI) quaternary body can be used as a substrate, wherein the element can be formed via photolithography and chemical etching, and then covered with a liquid photo-imageable (LPI) mask material. The terminals can be solderable and can be achieved by exposing the Cu on the terminals via laser stripping of the polyimide layer.

[0023] In another example, instead of laser stripping the Cu terminals, PCB rivets can be installed to provide electrical connections and mechanical fixation to the Cu strip, which will then act as solderable leads and extended fuse terminals. Tin (Sn) plated fuse terminals can optionally be provided for additional metal connections, where the plating can be formed by dipping.

[0024] Figure 1-3 A protection device (hereinafter referred to as "device") 100 according to an embodiment of the present disclosure is depicted. As shown, the device 100 may include a first main side 101 opposite to a second main side 102 and a first end 103 opposite to a second end 104. The device 100 may include a metal layer 108 (e.g., copper) formed into a fusible element 112, a first terminal 114, and a second terminal 116. It will be understood that the fusible element 112 is not limited to any particular shape or configuration. For example, although shown and described herein as being straight or substantially straight, the fusible element 112 may also be curved, angled, or bent. There may also be more than one fusible element 112. The embodiments herein are not limited to this context.

[0025] According to known electrical fuses, when a current of a predetermined magnitude flows through the fuse for a period of time (sometimes referred to as an overcurrent condition), which may damage sensitive electronic components, the fusible element 112 is constructed to melt, vaporize, decompose, or otherwise fail structurally. That is, the current path through the device 100 is designed to fail and disconnect the current path through the fusible element 112 to avoid damage to sensitive circuit components. The amount of current that the fusible element 112 can sustain before opening the current path can vary depending on its specific material properties and dimensional aspects. For such purposes, various fuse links or fuse element constructions are known. Once the fuse element 112 is disconnected, the fuse assembly 102 can be replaced to restore the circuit to full operation.

[0026] Device 100 may also include substrate 120, wherein metal layer 108 is coupled to an upper surface 122 of substrate 120. In some embodiments, first terminal 114 may extend beyond a first end 124 of substrate 120, and second terminal 116 may extend beyond a second end 126 of substrate 120. Substrate 120 may be a polyamide substrate.

[0027] As further shown, the device 100 may include a cover 130 extending over the fusible element 112. In other words, the metal layer 108 may be sandwiched by the substrate 120 and the cover 130. As shown, the cover 130 may further extend over the first terminal 114 and the second terminal 116. Although not limiting, the cover 130 may have similar dimensions (e.g., in the x-direction and the y-direction) as the substrate 120. In some embodiments, the cover 130 may be a liquid photoimaging mask, silicone, and / or other polymers. Once assembled, the thickness of the device 100 (in the z-direction) may be less than 0.4 mm. The method of forming the device 100 will be further described below.

[0028] In some embodiments, the device 100 may further include a metal element 133, which may be a Metcalfe effect (M-effect) coating of Sn applied to one or more surfaces of the fusible element 112. During overload heating, the Sn of the metal element 133 and the Cu of the fusible element 112 diffuse together in an attempt to form a eutectic material, resulting in a lower melting temperature in the metal element 133 region.

[0029] Figure 4-6 Another protection device (hereinafter referred to as "device") 200 according to an embodiment of the present disclosure is depicted. As shown, the device 200 may include a metal layer 208 (e.g., copper) formed into a fusible element 212, a first terminal 214, and a second terminal 216. It should be understood that the fusible element 212 is not limited to any particular shape or configuration. For example, although shown and described herein as being straight or substantially straight, the fusible element 212 may also be curved, angled, or bent. There may also be more than one fusible element 212. The embodiments herein are not limited to this context.

[0030] Device 200 may also include substrate 220, wherein metal layer 208 is coupled to an upper surface 222 of substrate 220. In some embodiments, first terminal 214 may extend beyond a first end 224 of substrate 220, and second terminal 216 may extend beyond a second end 226 of substrate 220. Substrate 220 may be a polyamide substrate.

[0031] As further shown, the device 200 may include a cover 230 extending over the fusible element 212, wherein the metal layer 208 may be sandwiched by the substrate 220 and the cover 230. In some embodiments, the cover 230 may further extend over the first terminal 214 and the second terminal 216. Although not limiting, the cover 230 may have similar dimensions (e.g., in the x-direction and the y-direction) as the substrate 220. In some embodiments, the cover 230 may be a liquid photoimaging mask.

[0032] In some embodiments, the device 200 may further include a metal element 233 , which may be a Metcalfe effect (M effect) coating of Sn applied to one or more surfaces of the fusible element 212 .

[0033] like Figure 5 As shown, the substrate 220 may include a first plurality of openings 240, the metal layer 208 may include a second plurality of openings 242, and the cover 230 may include a third plurality of openings 246. One or more fasteners 250 (e.g., rivets) may be formed through each opening to secure the layers of the device 200 together. The fasteners 250 may further provide electrical connections to the first terminal 214 and the second terminal 216. A method for forming the device 200 will be further described below.

[0034] like Figure 7-8 As shown, in some embodiments, the device 200 (and / or the device 100) may include one or more plating layers 255 formed on opposite sides of the cover 230 and the substrate 220. The plating layer 255 provides additional metal connection and may also be fixed by the fastener 250. The plating layer 255 may be electrically and physically connected to the first terminal 214 and the second terminal 216 of the metal layer 208. In some embodiments, the plating layer 255 may be Ni and Sn and / or Sn.

[0035] Now go to Fig. 9 , the method 300 for forming the device 100 will be described in more detail. At block 301, the method 300 may include preparing the fusible element 112. In some embodiments, the fusible element 112 is prepared using lamination, imaging, and development processes.

[0036] At block 302 , the method 300 may include etching the copper layer 108 to form the fusible element 112 based on a fabrication process.

[0037] At block 303, method 300 may include performing a selective SN point plating process to form metal element 133, and at block 304, method 300 may include forming cover 130 on fusible element 112. In some embodiments, cover 130 may be an LPI cover formed using a spray, image, develop, and then cure process. Alternatively, at block 304A, method 300 may include forming cover 130 using a polyamide press lamination process.

[0038] At block 305 , method 300 may include a marking formation process, which may include a series of spraying, imaging, developing, and curing steps.

[0039] At block 306, the method 300 may include removing a portion of the cover 130 from over the first terminal 114 and the second terminal 116. In some embodiments, the cover 130 is removed using a polyamide laser lift-off process.

[0040] At block 307 , method 300 may include performing a singulation process.

[0041] Now go to Fig.10 , the method 400 for forming the device 200 will be described in more detail. At block 401, the method 400 may include preparing the fusible element 212. In some embodiments, the fusible element 212 is prepared using lamination, imaging, and development processes.

[0042] At block 402 , the method 400 may include etching the copper layer 208 to form the fusible element 212 , followed by performing a selective SN point electroplating process to form the metal element 233 at block 403 .

[0043] At block 404, the method 400 may include forming the cover 230 on the fusible element 212, wherein the cover 230 may be an LPI cover formed using a spraying, imaging, developing, and then curing process. Alternatively, at block 404A, the method 400 may include forming the cover 230 using a polyamide press lamination process.

[0044] At block 405 , method 400 may include a marking formation process, which may include a series of spraying, imaging, developing, and curing steps.

[0045] At block 406 , a singulation process may be performed, followed by a lead assembly process at block 407 . In some embodiments, a plurality of rivets 250 are formed through various layers of device 200 .

[0046] At block 408 , an optional electroplating process may be performed. The plating may be Ni and Sn and / or Sn, which is formed on the first terminal 214 and on the second terminal 216 .

[0047] Figure 11-13 Another protection device (hereinafter referred to as "device") 500 according to an embodiment of the present disclosure is depicted. Device 500 may be the same or similar in some aspects to other devices described herein. Therefore, for the sake of brevity, only certain aspects of device 500 will be described below. As shown, device 500 may be a fusible element 512, a first terminal (or lead) 514, and a second terminal (or lead) 516. Fig.13 As best shown, the fusible element 512 may include a thinned central portion 521 extending between a first flange 523 and a second flange 525. In alternative embodiments, other shapes and configurations are possible.

[0048] Device 500 may also include substrate 520, wherein fusible element 512 is coupled to an upper surface of substrate 520. In some embodiments, first terminal 514 may abut first end 537 of substrate 520 and second end 526 of substrate 520. In the embodiment shown, substrate 520 may be a polyamide substrate.

[0049] As further shown, the device 500 may include a cover 530 extending over the fusible element 512, wherein the fusible element 512 may be sandwiched by the substrate 520 and the cover 530. In some embodiments, the cover 530 may further extend over the first terminal 514 and the second terminal 516. Although not limiting, the cover 530 may be larger (e.g., in the x-direction) than the substrate 520. In some embodiments, the cover 530 may be a liquid photoimaging mask.

[0050] like Fig.13 As best shown in FIG. 5 , the device 200 may further include a metal element 533, which may be a Metcalfe effect (M-effect) coating of Sn applied to one or more surfaces of the fusible element 512. As further shown, the first terminal 514 may include a first plurality of openings 540A, the second terminal 516 may include a second plurality of openings 540B, the fusible element 512 may include a third plurality of openings 542, and the cover 530 may include a fourth plurality of openings 546. One or more fasteners 550 (e.g., rivets) may be formed through each opening to secure the layers of the device 500 together. The fasteners 550 may further provide electrical connections to the first terminal 514 and the second terminal 516.

[0051] As used herein, an element or step listed 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 listed. 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.

[0052] The use of "including," "comprising," or "having" and variations thereof herein is intended to encompass the items listed below and equivalents thereof as well as additional items. Thus, the terms "including," "comprising," or "having" and variations thereof are open-ended expressions and may be used interchangeably herein.

[0053] As used herein, the phrases "at least one," "one or more," and "and / or" are open-ended expressions and are both conjunctive and disjunctive in operation. For example, the expressions "at least one of A, B, and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C," and "A, B, and / or C" mean A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

[0054] All directional references (e.g., proximal, distal, up, down, upward, downward, left, right, transverse, longitudinal, front, rear, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are used only for identification purposes to help the reader understand the present disclosure. Directional references do not create limitations, particularly with respect to the position, orientation, or use of the present disclosure. Connection references (e.g., attached, coupled, connected, and engaged) should be broadly understood and may include intermediate members between sets of elements and relative motion between elements, unless otherwise indicated. Therefore, a connection reference does not necessarily infer that two elements are directly connected and are in a fixed relationship to each other.

[0055] Furthermore, identifying references (e.g., primary, secondary, first, second, third, fourth, etc.) do not imply importance or priority, but are used to distinguish one feature from another. The drawings are for illustrative purposes, and the size, position, order, and relative sizes reflected in the drawings may vary.

[0056] In addition, the terms "substantially" or "approximately" and the terms "roughly" or "approximately" are used interchangeably in some embodiments and can be described using any relative measurement acceptable to one of ordinary skill in the art. For example, these terms can be used as a comparison to a reference parameter to indicate a deviation from being able to provide the intended function. Although not limiting, the deviation from the reference parameter can be, for example, an amount of less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, etc.

[0057] Although certain embodiments of the present disclosure have been described herein, the present disclosure is not limited thereto, as the scope of the present disclosure is as broad as the art allows, and the specification may be read similarly. Therefore, the above description should not be interpreted as limiting. On the contrary, the above description is only exemplary of a specific embodiment. Those skilled in the art will envision other modifications within the scope and spirit of the appended claims.

Claims

1. A protection device, comprising: substrate; a fusible element extending between a first terminal and a second terminal, wherein the fusible element, the first terminal, and the second terminal are coupled to the substrate; and A cover is formed on the fusible element, wherein the fusible element is positioned between the cover and the substrate.

2. The protection device according to claim 1, wherein: The covering portion is partially formed on the first terminal and the second terminal.

3. The protection device according to claim 1, wherein: The cover is a liquid photoimaging mask, a silicone mask or a polymer mask.

4. The protection device according to claim 1, wherein: The substrate is a polyimide substrate. 5 . The protection device of claim 1 , further comprising a plurality of fasteners coupling the cover, the substrate, and the fusible element together. 6 . The protection device according to claim 1 , further comprising a plating layer formed on the first terminal and the second terminal.

7. The protection device according to claim 1, further comprising a tin layer formed on the fusible element.

8. A method of forming a protection device, comprising: coupling a fusible element to the substrate, wherein the fusible element extends between a first terminal and a second terminal; and A cover is formed on the fusible element, wherein the fusible element is positioned between the cover and the substrate. 9 . The method of claim 8 , further comprising partially forming the covering portion on the first terminal and the second terminal.

10. The method according to claim 8, wherein: The covering portion is a liquid photoimaging mask.

11. The method according to claim 8, wherein: The substrate is a polyimide substrate.

12. The method of claim 8, further comprising coupling the cover, the substrate, and the fusible element together using a plurality of fasteners.

13. The method according to claim 12, wherein: The plurality of fasteners are rivets. 14 . The method of claim 8 , further comprising forming a plating layer on the first terminal and the second terminal.

15. The method according to claim 14, wherein: The plating layer is formed by immersing the first terminal and the second terminal in tin. 16 . The method of claim 8 , further comprising partially removing the cover to expose the first terminal and the second terminal.

17. The method according to claim 16, wherein: The cover is removed using a laser lift-off process.

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