PPTC device comprising multiple layers of electrodes

Abstract

A PPTC device including a plurality of layers of electrodes is provided. In some embodiments, a protection device assembly may include a protection feature, a first electrode layer extending along a first major side of the protection feature, and a second electrode layer extending along a second major side of the protection feature. The protection device assembly may further include a first substrate layer disposed over at least one of the first electrode layer and the second electrode layer; a foil layer disposed over the first substrate layer, wherein the foil layer is partially separated from the first electrode layer by the first substrate layer; and a pad extending around one end of the protective member and the first substrate layer, wherein the pad is in contact with the foil layer.

Description

Technical Field

[0001] The present disclosure generally relates to polymer positive temperature coefficient (PTC) devices, and more particularly, to polymer PTC devices including a multi-layer electrode. Background Art

[0002] A known resettable fuse is a positive temperature coefficient ("PTC") device. PTC thermistor materials rely on physical properties closely related to many conductive materials, that is, the resistivity of the conductive material increases with temperature. Crystalline polymers that conduct electricity through conductive fillers distributed therein exhibit this PTC effect. Polymers generally include polyolefins such as polyethylene, polypropylene, and ethylene / propylene copolymers. Certain doped ceramics such as barium titanate also exhibit PTC behavior.

[0003] The conductive filler causes the resistivity of the PTC thermistor material to increase as the temperature of the material increases. At temperatures below a certain value, the PTC thermistor material exhibits a relatively low and constant resistivity. However, when the temperature of the PTC thermistor material increases beyond this point, the resistivity increases sharply even with only a slight increase in temperature.

[0004] If the load protected by the PTC thermistor material is short-circuited, the current flowing through the PTC thermistor material increases, and the temperature of the PTC thermistor material (due to the above-mentioned I 2 R heating) rapidly rises to the critical temperature. At the critical temperature, the PTC thermistor material dissipates a large amount of power, resulting in the rate of heat generation of the material being greater than the rate at which the material can dissipate heat to its surrounding environment. The power dissipation only occurs within a short period of time (e.g., a fraction of a second). However, the increased power dissipation increases the temperature and resistance of the PTC thermistor material, thereby limiting the current in the circuit to a relatively low value. Therefore, the PTC thermistor material is used in the form of a fuse.

[0005] Once the current in the circuit is interrupted or the condition causing the short circuit is eliminated, the PTC thermistor material cools to below its critical temperature and reaches its normal operating low-resistance state. The result is a resettable overcurrent circuit protection material.

[0006] Even though the PTC thermistor material operates at a lower resistance under normal conditions, the normal operating resistance of the PTC thermistor material is higher than that of other types of fuses, such as non-resettable metal fuses.

[0007] Therefore, there is a need for improved devices with a small package size. Summary of the Invention

[0008] In one or more embodiments, a protection device assembly may include: a protection component, a first electrode layer extending along a first major side of the protection component, and a second electrode layer extending along a second major side of the protection component. The protection device assembly may further include: a first substrate layer disposed above at least one of the first electrode layer and the second electrode layer; a foil layer disposed above the first substrate layer, wherein the foil layer is partially separated from the first electrode layer by the first substrate layer; and a pad extending around one end of the protection component and the first substrate layer, wherein the pad is in contact with the foil layer.

[0009] In one or more embodiments, a polymer positive temperature coefficient (PPTC) device may include: a PPTC protection component; a first electrode layer extending along a first major side of the PPTC protection component; and a second electrode layer extending along a second major side of the PPTC protection component. The PPTC protection component may further include: a first substrate layer disposed above the first electrode layer and a second substrate layer disposed above the second electrode layer; and a first foil layer disposed above the first substrate layer, wherein the foil layer is partially separated from the electrode layer by the first substrate layer. The PPTC protection component may further include: a second foil layer disposed above the second substrate layer, wherein the second foil layer is partially separated from the second electrode layer by the second substrate layer; and a pad extending around one end of the PPTC protection component and the first substrate layer, wherein the pad is in contact with the first foil layer or the second foil layer.

[0010] In one or more embodiments, a method of forming a protection device assembly may include: providing a PPTC protection component; forming a first electrode layer along a first major side of the PPTC protection component; and forming a second electrode layer along a second major side of the PPTC protection component. The method may further include: forming a first substrate layer above the first electrode layer and forming a second substrate layer above the second electrode layer; and forming a first foil layer above the first substrate layer, wherein the foil layer is partially separated from the first electrode layer by the first substrate layer. The method may further include: forming a second foil layer above the second substrate layer, wherein the second foil layer is partially separated from the second electrode layer by the second substrate layer; and forming a pad around one end of the PPTC protection component and around the first substrate layer, wherein the pad is in contact with the first foil layer or the second foil layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings illustrate example methods of the disclosed embodiments designed thus far for practical applications of their principles, wherein:

[0012] Figure 1AA picture of a side view of a component according to an exemplary method of the present disclosure;

[0013] Figure 1B A side view of a component according to an exemplary method of the present disclosure;

[0014] Figure 2 According to an exemplary method of the present disclosure Figure 1B A top view of the component along the cutting plane A-A;

[0015] Figure 3 A top view of a component according to an exemplary method of the present disclosure;

[0016] Figure 4 According to an exemplary method of the present disclosure Figure 3 A side cross-sectional view of the device of the component along the cutting plane B-B;

[0017] Figure 5 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0018] Figure 6 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0019] Figure 7 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0020] Figure 8 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0021] Figure 9 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0022] Figure 10 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0023] Figure 11 Shows the voltage and resistance of a device according to an exemplary method of the present disclosure Figure 10 of the device;

[0024] Figure 12 A side cross-sectional view of a device according to an exemplary method of the present disclosure;

[0025] Figure 13 Describes the process of forming a PPTC device according to an exemplary method of the present disclosure;

[0026] Figures 14 - 15 Describes an exemplary foil layer according to an embodiment of the present disclosure.

[0027] The accompanying drawings are not necessarily drawn to scale. The drawings are merely illustrative and are not intended to depict the specific parameters of the present disclosure. The drawings are intended to depict typical embodiments of the present disclosure and should not be construed as limiting in scope. In the drawings, like numerals represent like elements.

[0028] In addition, for clarity of illustration, some elements in some of the figures may be omitted or not drawn to scale. Further, for clarity, some reference numerals may be omitted in some of the drawings. Detailed Description

[0029] Embodiments in accordance with the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. The devices, apparatuses, and methods may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the systems and methods to those skilled in the art.

[0030] As will be described herein, embodiments of the present disclosure provide a PPTC device that includes one or more multi-layer electrode structures. The PPTC may be composed of an organic conductive layer, a conductive electrode layer (e.g., made of copper), a high-resistance electrode layer, an insulating layer (e.g., a substrate made of prepreg or FR4, ceramic, etc.), and / or a coating layer. The organic conductive layer may be a polymer positive temperature component (e.g., made of a PTC solid sheet or liquid material) layer. The high-resistance electrode may be made of a conductive layer that indirectly contacts the positive temperature component.

[0031] The PPTC of the present disclosure improves the resistance distribution, where the total resistance is composed of a PTC resistance (i.e., a variable resistance) and a high-resistance foil (i.e., a fixed resistance). The high-resistance foil is separated by one or more insulating layers, which enables the foil to function as an independent electrode, thus creating more space for resistance design. Compared with the traditional application where the PTC is the total resistance source, the high-resistance foil layer shares more of the resistance, which can tighten the resistance window for specific applications. In addition, since the high-resistance foil shares the voltage drop in series for each layer of the structure with the PTC layer, the voltage withstand performance can be improved.

[0032] Turning Figures 1A - 1B , an embodiment of a component 100 and a device 102 in accordance with the present disclosure is shown. As shown, the device 102 may be a PTC device or a polymer PTC device. In some embodiments, the device 102 may be an Electronic Industries Alliance (EIA) surface mount device, e.g., of the advanced SMDC0201 type. For ease of explanation, the device 102 may be defined by an opposite first end 125 and second end 127 and opposite top side 105 and bottom side 107. The device 102 may also include opposite first and second sides (e.g., within the page and out of the page).

[0033] The device 102 includes a protection component 104 disposed between a first substrate layer 106 and a second substrate layer 108. A third substrate layer 110 may be on top of the first substrate layer 106, and a fourth substrate layer 111 may be under the second substrate layer 108. Additional substrate layers may be present in alternative embodiments. In some embodiments, the substrate layers are made of the same material, such as FR-4 material or polyimide. The illustrated device 102 may be located, for example, in the charge / discharge circuit of a secondary battery and serve as a circuit protection device to interrupt such current when an overcurrent passes through the circuit. As Figure 1B shown, the device 102 may be connected to a printed circuit board (PCB) 112 by soldering.

[0034] In some embodiments, the protection component 104 is selected from the non-limiting group consisting of fuses, PTCs, NTCs, ICs, sensors, MOSFETs, resistors, and capacitors. Among these protection components, ICs and sensors are considered active protection components, while PTCs, NTCs, and fuses are considered passive components. In the illustrated embodiment, the protection component 104 may be a polymeric PTC. However, it should be understood that such an arrangement is non-limiting and the number and configuration of the protection components may vary according to the application.

[0035] The PTC material of the protection component 104 may be made of a positive temperature coefficient conductive composition comprising a polymer and a conductive filler. The polymer of the PTC material may be a crystalline polymer selected from the group consisting of polyethylene, polypropylene, polyoctene, polyvinylidene chloride, and mixtures thereof. The conductive filler may be dispersed in the polymer and is selected from the group consisting of carbon black, metal powder, conductive ceramic powder, and mixtures thereof. In addition, to improve the sensitivity and physical properties of the PTC material, the PTC conductive composition may further include additives such as photoinitiators, crosslinking agents, coupling agents, dispersants, stabilizers, antioxidants, and / or non-conductive arc-proof fillers.

[0036] As shown, a first electrode layer 114 may extend along a first major side 116 of the protection component 104, and a second electrode layer 118 may extend along a second major side 120 of the protection component 104. The first substrate layer 106 may be disposed above the first electrode layer 114, while the second substrate layer 108 may be disposed around / above the second electrode layer 118 such that the second electrode layer 118 is located between the second major side 120 of the protection component 104 and the second substrate layer 108.

[0037] The first electrode layer 114 and the second electrode layer 118 may be made of copper. However, it should be understood that alternative materials may be used. For example, the first electrode layer 114 and the second electrode layer 118 may be one or more metals, such as silver, copper, nickel, tin, and their alloys, and may be applied to the surfaces of the first major side 116 and the second major side 120 and / or the first substrate layer 106 and the second substrate layer 108 in any number of ways. For example, the first electrode layer 114 and the second electrode layer 118 may be applied by electroplating, sputtering, printing, laminating, etc.

[0038] The device 102 may further include a first foil layer 122 formed on top of the first substrate layer 106 and a second foil layer 123 formed under the second substrate layer 108. A third substrate layer 110 may be formed around the first foil layer 122, while a fourth substrate layer 111 may be formed around the second foil layer 123. The first foil layer 122 and the second foil layer 123 may be high-resistance layers. The resistance of the first foil layer 122 and the second foil layer 123 may be greater than the resistance of the first electrode layer 114 and the second electrode layer 118. In some embodiments, one or more materials for the first foil layer 122 and the second foil layer 123 may be electroless nickel phosphorus alloy plated with copper and / or nickel chromium alloy.

[0039] As further shown, a first pad 124 may extend around the first end 125 of the protection component 104, and a second pad 126 may extend around the second end 127 of the protection component 104. In some embodiments, the first pad 124 may be formed above the third substrate layer 110 and below the fourth substrate layer 111, and may be in contact with the first foil layer 122. The second pad 126 may be formed above the third substrate layer 110 and below the fourth substrate layer 111, and may be in contact with the second foil layer 123. The first pad 124 and the second pad 126 may be terminals formed by, for example, standard electroplating techniques. The terminals may be multi-layer metals, such as electrolytic copper, electrolytic tin, silver, nickel, or other metals or alloys as required. The terminals are sized and configured such that the device 102 can be mounted onto the PCB 112 in a surface-mount manner.

[0040] Refer to Figure 2, the first foil layer 122 will be described in more detail. As further shown, the first foil layer 122 may include a first portion 130 extending between the first side 138 and the second side 133 of the device 102. In the illustrated embodiment, the first portion 130 further extends to the first end 125 of the device 102. The first foil layer 122 may also include a second portion 132 extending between the first side 138 and the second side 133 of the device 102. As shown, the second portion 132 is electrically connected to the first electrode 114, and the first electrode 114 extends through an opening in the second portion 132. In some embodiments, the second portion 132 does not fully extend to the second end 127 of the device 102. The first foil layer 122 may also include a third portion 136 connecting the first portion 130 and the second portion 132. As shown, the third portion 136 may be partially surrounded by the third substrate layer 110. In some embodiments, a first width "W1" of the first portion 130 in the x direction is less than a second width "W2" of the second portion 132. Although not shown, the second electrode layer 118 and the second foil layer 123 may be configured to be substantially the same as the first electrode layer 114 and the first foil layer 122. In other embodiments, the second electrode layer 118 may have a different layout from the first electrode layer 114, and / or the second foil layer 123 may have a different layout from the first foil layer 122.

[0041] Referring again to Figure 1B , a second portion 132 of the first foil layer 122 may be substantially vertically aligned with the first electrode layer 114. In addition, the second portion of the first foil layer 122 may have substantially the same width as the first electrode layer 114 (e.g., in the x direction). The second foil layer 123 and the second electrode layer 118 may be similarly arranged along the lower side of the protective member 104. In the illustrated embodiment, both the second portion 132 of the first foil layer 122 and the first electrode layer 114 may extend substantially to the center line "CL" of the device 102, and the second pad 126 may partially extend over the second portion 132 of the first foil layer 122 and the first electrode layer 114. At the same time, the first pad 124 may completely extend over the first portion 130 of the first foil layer 122. Similarly, both the second portion 137 of the second foil layer 123 and the second electrode layer 118 may extend substantially to the center line "CL" of the device 102, and the first pad 124 may partially extend over the second portion 137 of the second foil layer 123 and the second electrode layer 118. The second pad 126 may completely extend over the first portion 139 of the second foil layer 123.

[0042] In Figure 1AIn an embodiment, the second portion 132 of the first foil layer 122 and the first electrode layer 114 may be offset relative to each other along the x direction. For example, the second portion 132 of the first foil layer 122 may extend closer to the center of the device 102 than the first electrode layer 114, while the first electrode layer 114 may extend closer to the second end 127 of the device 102. Additionally, the second electrode layer 118 may extend closer to the center of the device 102 than the second portion 137 of the second foil layer 123, while the second portion 137 of the second foil layer 123 may extend closer to the first end 125 of the device 102.

[0043] Figure 4 is a side cross-sectional view of the device 102 along Figure 3 section line B-B. As shown, the section line B-B passes through the center of the third portion 136 of the first foil layer 122 and through the center of the third portion 142 of the second foil layer 123. As shown, the first electrode layer 114 and the second electrode layer 118 may each include a base 144 and a through hole 145 extending from the base 144. In this embodiment, the base 144 of the first electrode 114 is directly disposed on top of the first main side 116 of the protective member 104, and the through hole 145 extends from the base 144 and passes through the opening of the first foil layer 122. Similarly, the base 144 of the second electrode layer 118 is in direct contact with the second main side 120 of the protective member 104, and the through hole 145 extends from the base 144 and passes through the opening of the second foil layer 123.

[0044] In the device 102, voltage and resistance are divided among the first foil layer 122, the protective member 104, and the second foil layer 123. The total resistance R total of the device 102 is given by R1 + R2 + R3, while the total voltage V total of the device 102 is given by V1 + V2 + V3.

[0045] Figure 5 Shows another device 102A according to an embodiment of the present disclosure. The device 102A may be the same as or similar to the above-described device 102. Therefore, for the sake of brevity, only certain aspects of the device 102A will be described below.

[0046] As shown, the first electrode layer 114 and the second electrode layer 118 may each include a base 144 and a through hole 145 extending from the base 144. In this embodiment, the base 144 of the first electrode 114 is directly disposed on top of the first main side 116 of the protective member 104, and the through hole 145 extends from the base 144 and passes through the opening of the first foil layer 122. Similarly, the base 144 of the second electrode layer 118 is in direct contact with the second main side 120 of the protective member 104, and the through hole 145 extends from the base 144 and passes through the opening of the second foil layer 123.

[0047] The base 144 of the first electrode layer 114 may be separated from the first foil layer 122 by the first substrate layer 106 and may have a width (e.g., in the x-direction) defined by a first end 150 and a second end 151. As shown, the first end 150 may be covered or overlapped by the first pad 124 in the y-direction, while the second end 151 may be covered or overlapped by the second pad 126 in the y-direction. In the illustrated embodiment, the first end 150 is substantially aligned with the first end 153 of the first foil layer 122, while the second end 154 of the first foil layer 122 extends to the second pad 126.

[0048] The base 144 of the second electrode layer 118 may be separated from the second foil layer 123 by the second substrate layer 108 and may have a width (e.g., in the x-direction) defined by a first end 155 and a second end 156. As shown, the first end 155 may be covered or overlapped by the first pad 124 in the y-direction, while the second end 156 may be covered or overlapped by the second pad 126 in the y-direction. In the illustrated embodiment, the second end 156 is substantially aligned with the first end 157 of the second foil layer 123, while the second end 158 of the first foil layer 122 extends to the first pad 124.

[0049] As further shown, the coating layer 149 may be provided along one or more sides of the device 102A. For example, the coating layer 149 may be formed on top of the third substrate layer 110, and the coating layer 149 may be formed along the fourth substrate layer 111. The coating layer 149 may be disposed between the first pad 124 and the second pad 126.

[0050] In the device 102A, voltage and resistance are divided among the first foil layer 122, the protection component 104, and the second foil layer 123. As shown, the total resistance R of the device 102A total is given by R1 + R2 + R3, while the total voltage V of the device 102A total is given by V1 + V2 + V3.

[0051] Figure 6 Another device 102B according to an embodiment of the present disclosure is shown. The device 102B may be the same as or similar to the above-described device. Therefore, for the sake of brevity, only certain aspects of the device 102B will be described below.

[0052] As shown, the first electrode layer may include a first portion 114A separated from a second portion 114B by a first substrate layer 106. Each of the first portion 114A and the second portion 114B may have a base 144 and a via 145 extending from the base 144. Similarly, the second electrode layer may include a first portion 118A separated from a second portion 118B by a second substrate layer 108, wherein each of the first portion 118A and the second portion 118B may include a via 145 extending from the base 144 and passing through an opening in the first foil layer 122. In this embodiment, the bases 144 of the first portion 114A and the second portion 114B are disposed directly on top of the first major side 116 of the protection member 104, while the vias 145 extend perpendicularly from each respective base 144. Similarly, the bases 144 of the first portion 118A and the second portion 118B of the second electrode layer are in direct contact with the second major side 120 of the protection member 104, while the via 144 extends through the second substrate layer 108 and contacts the first pad 124 and the second pad 126.

[0053] In the illustrated embodiment, the first pad 124 and the second pad 126 extend only along the bottom of the second substrate 108 and do not wrap around the first end 125 and the second end 127 of the device 102B. Alternatively, a third substrate layer 159 may be formed above the first foil layer 122 and wrap around the protection member 104 and the sides of the first electrode layer and the second electrode layer.

[0054] In the device 102B, voltage and resistance are divided between the first foil layer 122 and the protection member 104. As shown, the total resistance R of the device 102B total is given by R1+R2+R3, while the total voltage V of the device 102B total is given by V1+V2+V3.

[0055] Figure 7 Another device 102C according to an embodiment of the present disclosure is shown. The device 102C may be the same as or similar to the above-described device. Therefore, for the sake of brevity, only certain aspects of the device 102C will be described below.

[0056] As shown in the figure, the first electrode layer 114 is directly disposed on top of the first main side 116 of the protection component 104, and the first substrate layer 106 is formed above the first electrode layer 114. The second electrode layer 118 is formed along the second main side 120 of the protection component 104 and includes a through hole 145 extending from a base 144. The through hole 145 extends through the second substrate layer 108 and through an opening in the second foil layer 123. The fourth substrate layer 111 may be formed under the second foil layer 123. In the illustrated embodiment, the first pad 124 and the second pad 126 extend around the first end 125 and the second end 127 of the device 102C, including extending under the fourth substrate layer 111.

[0057] In the device 102C, the voltage and the resistance are divided between the second foil layer 123 and the protection component 104. As shown, the total resistance R of the device 102C total is given by R1 + R2, while the total voltage V of the device 102C total is given by V1 + V2.

[0058] Figure 8 Another device 102D according to an embodiment of the present disclosure is shown. The device 102D may be the same as or similar to the above-described device. Therefore, for the sake of brevity, only certain aspects of the device 102D will be described below.

[0059] As shown, the first electrode layer 114 and the second electrode layer 118 may each include a base 144 and a through hole 145 extending from the base 144. In this embodiment, the base 144 of the first electrode 114 is directly disposed on top of the first main side 116 of the protection component 104, and the through hole 145 extends from the base 144 and through an opening in the first foil layer 122. Similarly, the base 144 of the second electrode layer 118 is in direct contact with the second main side 120 of the protection component 104, and the through hole 145 extends from the base 144 and through an opening in the second foil layer 123.

[0060] The base 144 of the first electrode layer 114 may be separated from the first foil layer 122 by the first substrate layer 106, while the third substrate layer 110 is formed above the first foil layer 122. Similarly, the base 144 of the second electrode layer 118 may be separated from the second foil layer 123 by the second substrate layer 106, while the fourth substrate layer 111 is formed under the second foil layer 123. In this embodiment, the first electrode layer 114 and the second electrode layer 118 are not covered or overlapped by the first pad 124 or the second pad 126 in the y direction. At the same time, the first foil layer 122 may extend to the second pad 126, and the second foil layer 123 may extend to the first pad 124.

[0061] In device 102D, voltage and resistance are divided among the first foil layer 122, the protection component 104, and the second foil layer 123. The total resistance R of device 102D total is given by R1 + R2 + R3, and the total voltage V of device 102D total is given by V1 + V2 + V3.

[0062] Figure 9 Another device 102E according to an embodiment of the present disclosure is shown. Device 102E may be the same as or similar to the above-described device. Therefore, for the sake of brevity, only certain aspects of device 102E will be described below.

[0063] As shown, the second electrode layer 118 is formed along the second major side 120 of the protection component 104 and includes through-holes 145 extending from the base 144. The through-holes 145 extend through the second substrate layer 108 and through the openings in the second foil layer 123. The fourth substrate layer 111 may be formed under the second foil layer 123. In the illustrated embodiment, the first pad 124 and the second pad 126 extend around the first end 125 and the second end 127 of device 102E, including extending under the fourth substrate layer 111.

[0064] In device 102E, voltage and resistance are divided between the second foil layer 123 and the protection component 104. As shown, the total resistance R of device 102E total is given by R1 + R2, and the total voltage V of device 102E total is given by V1 + V2.

[0065] Figure 10 Another device 102F according to an embodiment of the present disclosure is shown. Device 102F may be the same as or similar to the above-described device. Therefore, for the sake of brevity, only certain aspects of device 102F will be described below.

[0066] As shown, the first electrode layer may include a first portion 114A separated from a second portion 114B by a first substrate layer 106 and a third substrate layer 110. Each of the first portion 114A and the second portion 114B may have a base 144 and a via 145 extending from the base 144. Each via 145 may extend through an opening in the first foil layer 122. Similarly, the second electrode layer may include a first portion 118A separated from a second portion 118B by a second substrate layer 108 and a fourth substrate layer 111, wherein each of the first portion 118A and the second portion 118B may include a via 145 extending from the base 144 and through an opening in the first foil layer 122. In this embodiment, the bases 144 of the first portion 114A and the second portion 114B are disposed directly on top of a first major side 116 of the protective member 104, while the vias 145 extend perpendicularly from each respective base 144. Similarly, the bases 144 of the first portion 118A and the second portion 118B of the second electrode layer are in direct contact with a second major side 120 of the protective member 104, while the via 144 extends through the second substrate layer 108 and through an opening in the second foil layer 123. As shown, the third substrate layer 110 may be formed above the first foil layer 122, and the fourth substrate layer 111 may be formed below the second foil layer 123. In some embodiments, the first foil layer 122 may have a first portion 122A and a second portion 122B separated by a gap 161, and the second foil layer 123 may have a first portion 123A and a second portion 123B separated by a gap 162. The first foil layer 122 may be formed on top of the first substrate layer 106, and the second foil layer 123 may be formed below the second substrate layer 108.

[0067] As further shown, a coating layer 149 may be provided along one or more sides of the device 102F. For example, the coating layer 149 may be formed on top of the third substrate layer 110, and the coating layer 149 may be formed along the fourth substrate layer 111.

[0068] As Figure 11 shown, the voltage and resistance of the device 102F are divided among a first portion 122A of the first foil layer 122, a second portion 122B of the first foil layer 122, the protective member 104, a first portion 123A of the second foil layer 123, and a second portion 123B of the second foil layer 123. As shown, the total resistance R total of the device 102F is given by R total = ((R1 + R2 + R3)(R4 + R5 + R6) / (R1 + R2 + R3 + R4 + R5 + R6)). The total voltage V total of the device 102F is given by V total = V1 + V2 + V3 = V4 + V5 + V6.

[0069] Figure 12 It shows that multiple devices can be stacked in the same structure. For example, the first device 102D-1 can be stacked on the second device 102D-2, and the first pad 124 and the second pad 126 are formed around both. In the illustrated embodiment, the fourth substrate layer 111 of the first device 102D-1 can be directly positioned on top of the third substrate layer 110 of the second device 102D-2. It should be understood that the first device 102D-1 and the second device 102D-2 may have the same or different structures / configurations.

[0070] Figure 13 It shows a method 200 for forming one or more devices described herein. At block 201, the method 200 may include extruding a polymer to form a protective component. In some embodiments, the protective component may be a PPTC protective component.

[0071] At block 202, the method 200 may include laminating a copper layer over the protective component.

[0072] At block 203, the method 200 may include etching the copper layer into a desired configuration to form one or more electrodes. In various embodiments, the copper can be etched into any of the electrode layers described herein.

[0073] At block 204, the method 200 may include laminating a first substrate layer over the copper layer.

[0074] At block 205, the method 200 may include laminating a high-resistance foil over the first substrate layer and then, as shown at block 206, etching the high-resistance foil to obtain a fixed resistance value.

[0075] At block 207, the method 200 may further include forming an opening or hole through the high-resistance foil. In some embodiments, the opening is a laser-machined hole.

[0076] At block 208, the method 200 may further include electroplating a copper layer to fill the opening formed through the high-resistance foil to provide conduction between the copper layer and the high-resistance foil.

[0077] At block 209, the method 200 may further include laminating another substrate layer over the high-resistance foil.

[0078] At block 210, the method 200 may further include nickel plating and / or tin plating processes to form the first pad and the second pad.

[0079] At block 211, the method 200 may further include dicing the layers to form the devices.

[0080] In some embodiments, one or more of process steps 201 to 209 may be repeated to form layers along the second major side of the protective component before the electroplating process at block 210. For example, one or more electrode layers and one or more high-resistance foil layers may be patterned along the second major side of the protective component using the methods described above.

[0081] Figures 14 - 15 Some non-limiting examples of the first foil layer 122 and / or the second foil layer 123 described herein are shown. Notably, the third portion 136 extending between the first portion 130 and the second portion 132 may take various shapes, thicknesses, configurations, etc. as needed to adjust the resistance of the foil layer.

[0082] In summary, the multi-layer electrode structure of the present disclosure advantageously enables the high-resistance foil to function as an independent layer, providing more room for resistance design and thus resulting in a greater shared resistance to tighten the distribution. Additionally, the multi-layer electrode structure advantageously provides higher bonding strength to prevent delamination and cracking of the PPTC device. The multi-layer electrode structure is designed to connect all conductive parts in series, which provides a shared voltage across each conductive part. This prevents all voltage from passing only through the PTC and improves the voltage withstand performance (i.e., trip durability). Furthermore, the embodiments herein advantageously provide a novel manufacturing process for increasing miniaturization and diversification of components.

[0083] The foregoing discussion has been presented for purposes of illustration and description and is not intended to limit the present disclosure to one or more forms disclosed herein. For example, for the purpose of simplifying the present disclosure, various features of the present disclosure may be grouped together in one or more aspects, embodiments, or configurations. However, it should be understood that the various features of certain aspects, embodiments, or configurations of the present disclosure may be combined in alternative aspects, embodiments, or configurations. Additionally, the appended claims are incorporated by reference into this detailed description, where each claim stands alone as a separate embodiment of the present disclosure.

[0084] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood to not exclude a plurality of elements or steps, unless such exclusion is explicitly recited. Additionally, a reference to "one embodiment" of the present disclosure is not to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0085] The use of "comprising," "including," or "having" and variations thereof herein is intended to encompass the items listed thereafter and their equivalents as well as additional items. Thus, the terms "comprising," "including," or "having" and variations thereof are open-ended expressions and may be used interchangeably herein.

[0086] The phrases “at least one,” “one or more,” and “and / or” as used herein are open-ended expressions that are both combinative and separable in operation. For example, each of 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” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

[0087] All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are only for identification purposes to assist the reader in understanding the present disclosure and do not impose a limitation, particularly as to the position, orientation, or use of the present disclosure. Unless otherwise noted, connection references (e.g., attached, coupled, connected, and joined) shall be construed broadly and may include intermediate members between elements and relative movement between elements. Thus, a connection reference does not necessarily infer that the two elements are directly connected and in a fixed relationship to each other.

[0088] Furthermore, identification references (e.g., primary, secondary, first, second, third, fourth, etc.) are not intended to imply importance or priority but rather are used to distinguish one feature from another. The drawings are for illustrative purposes only, and the dimensions, positions, sequences, and relative dimensions reflected in the attached drawings herein may vary.

[0089] In addition, the terms “substantially” or “essentially” and the terms “approximately” or “about” may be used interchangeably in some embodiments and may be described using any relative measure acceptable to a person of ordinary skill in the art. For example, these terms may be used as a comparison with a reference parameter to indicate a deviation that can provide the intended function. Although not limiting, the deviation from the reference parameter may be, for example, an amount less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, etc.

[0090] Moreover, although the method 200 illustrated above is described as a series of acts or events, the present disclosure is not limited by the illustrated ordering of such acts or events unless specifically stated. For example, according to the present disclosure, some acts may occur in a different order and / or concurrently with other acts or events other than those shown and / or described herein. Additionally, not all of the illustrated acts or events may be required to implement the method according to the present disclosure. Furthermore, the method 200 may be implemented in association with the formation and / or processing of the structures shown and described herein and in association with other structures not shown.

[0091] The present disclosure is not limited in scope by the specific embodiments described herein. Indeed, various other embodiments and modifications of the present disclosure will be apparent to those of ordinary skill in the art from the foregoing description and the accompanying drawings. Accordingly, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Additionally, the present disclosure has been described herein in the context of particular embodiments in a particular environment for a particular purpose. Those of ordinary skill in the art will recognize that the utility is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth hereinafter will be interpreted in accordance with the full scope and spirit of the present disclosure as described herein.

Claims

1. A protection device assembly, comprising: a protection component; an electrode layer extending along at least one of a first major side and a second major side of the protection component; a substrate layer disposed above the electrode layer; a foil layer disposed above the substrate layer, wherein the foil layer is partially separated from the electrode layer by the substrate layer; and a pad extending around one end of the protection component and the substrate layer, wherein the pad is in contact with the foil layer.

2. The protection device assembly according to claim 1, further comprising a second substrate layer disposed on the substrate layer.

3. The protection device assembly according to claim 1, further comprising a second pad extending around a second end of the protection component and the substrate layer.

4. The protection device assembly according to claim 1, further comprising a printed circuit board, wherein the first pad and the second pad are connected to the printed circuit board by solder.

5. The protection device assembly according to claim 1, wherein the foil layer has a higher resistance than the electrode layer.

6. The protection device assembly according to claim 1, wherein the foil layer comprises: a first portion extending between a first side and a second side of the protection component; a second portion extending between the first side and the second side of the protection component, wherein the second portion is electrically connected to the electrode layer; and a third portion extending between the first portion and the second portion.

7. The protection device assembly according to claim 6, wherein the second portion is vertically aligned with the electrode layer.

8. The protection device assembly according to claim 1, wherein the protection component is a polymer positive temperature coefficient (PPTC) component.

9. A polymer positive temperature coefficient (PPTC) device, comprising: a PPTC protection component; an electrode layer extending along at least one of a first major side and a second major side of the PPTC protection component; a substrate layer disposed above the electrode layer; a first foil layer disposed above the substrate layer, wherein the first foil layer is partially separated from the electrode layer by the substrate layer; and a pad extending around one end of the PPTC protection component and the substrate layer, wherein the pad is in contact with the first foil layer.

10. The PPTC device according to claim 9, wherein the electrode layer comprises a first electrode layer extending along a first major side of the PPTC protection component and a second electrode layer extending along a second major side of the PPTC protection component, wherein a second foil layer is disposed above a second substrate layer disposed above the second electrode layer, wherein the second foil layer is partially separated from the second electrode layer by the second substrate layer.

11. The PPTC device according to claim 10, further comprising: a third substrate layer disposed above the first substrate layer and a fourth substrate layer disposed above the second substrate layer; and a coating layer disposed on top of at least one of the third substrate layer and the fourth substrate layer.

12. The PPTC device according to claim 10 further includes a second pad extending around the second end of the protection component and the first liner layer.

13. The PPTC device according to claim 10, wherein the first foil layer and the second foil layer have a higher resistance than the first electrode layer and the second electrode layer.

14. The PPTC device according to claim 10, wherein the first foil layer comprises: a first portion extending between a first side and a second side of the protection component; a second portion extending between the first side and the second side of the protection component, wherein the second portion is electrically connected to the first electrode; and a third portion extending between the first portion and the second portion.

15. The PPTC device according to claim 14, wherein the second portion of the first foil layer is vertically aligned with the first electrode layer.

16. A method of forming a protection device assembly, comprising: providing a PPTC protection component; forming a first electrode layer along a first major side of the PPTC protection component; forming a second electrode layer along a second major side of the PPTC protection component; forming a first liner layer above the first electrode layer and forming a second liner layer disposed above the second electrode layer; forming a first foil layer above the first liner layer, wherein the first foil layer is partially separated from the first electrode layer by the first liner layer; forming a second foil layer above the second liner layer, wherein the second foil layer is partially separated from the second electrode layer by the second liner layer; and forming a pad around one end of the PPTC protection component and around the first liner layer, wherein the pad is in contact with the first foil layer or the second foil layer.

17. The method according to claim 16 further includes forming a third liner layer above the first liner layer and forming a fourth liner layer above the second liner layer.

18. The method according to claim 17 further includes forming a coating layer on top of at least one of the third liner layer and the fourth liner layer.

19. The method according to claim 16 further includes forming a second pad around the second end of the protection component and the first liner layer.

20. The method according to claim 16, wherein the first foil layer and the second foil layer have a higher resistance than the first electrode layer and the second electrode layer.

21. The method according to claim 16 further includes connecting the first foil layer to the first electrode.

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