KR20230122828A - Ceramic protect device having electrode integrated fuse member and secondary battery charging apparatus having the same - Google Patents

Abstract

The present invention provides a ceramic protection element including an electrode-integrated fuse member that can be formed through a simplified process. According to one embodiment of the present invention, the ceramic protection element includes a ceramic substrate; an upper electrode for a fuse positioned on the ceramic substrate; a connection terminal positioned on the ceramic substrate; a fuse member electrically connecting the upper electrode for the fuse and the connection terminal; a heat generating member disposed between the ceramic substrate and the fuse member and generating heat when a current is applied to cut the fuse member; and a flow blocking member positioned on the ceramic substrate, having a shape of a dam structure surrounding the fuse member, and blocking flow after the fuse member is melted.

Description

A ceramic protection device including an electrode integrated fuse member and a secondary battery charging device including the same

The technical idea of the present invention relates to a ceramic protection element, and more particularly, to a ceramic protection element including an electrode-integrated fuse member and a secondary battery charging device including the same.

The protection element serves to prevent overcurrent and overvoltage from being applied to the secondary battery. The protection element is composed of a laminated structure in which a heating element, an insulating layer, an electrode, and a low melting point metal fuse member are sequentially laminated on a substrate. When an overvoltage is applied to the protection element, the heating element generates heat, and accordingly, the low melting point metal fuse member is blown.

Conventional protection elements have a limitation in that the number of manufacturing steps increases because a printing process and a firing process must be repeated in order to sequentially form a heating element, an insulating layer, and an electrode on a fired ceramic substrate.

Korean Patent Application No. 10-2012-0052661

A technical problem to be achieved by the technical idea of the present invention is to provide a ceramic protection element including an electrode-integrated fuse member that can be formed through a simplified process and a secondary battery charging device including the same.

However, these tasks are exemplary, and the technical spirit of the present invention is not limited thereto.

According to one aspect of the present invention, a ceramic protection element including an electrode-integrated fuse member that can be formed through a simplified process and a secondary battery charging device including the same are provided.

According to one embodiment of the present invention, the ceramic protection element, a ceramic substrate; an upper electrode for a fuse positioned on the ceramic substrate; a connection terminal positioned on the ceramic substrate; a fuse member positioned on the ceramic substrate and electrically connecting the upper electrode for the fuse and the connection terminal; a heat generating member disposed between the ceramic substrate and the fuse member and generating heat when a current is applied to cut the fuse member; and a flow blocking member positioned on the ceramic substrate, having a shape of a dam structure surrounding the fuse member, and blocking flow after the fuse member is melted.

According to an embodiment of the present invention, a fuse accommodating member disposed on the fuse member may be further included, and the fuse accommodating member is melted by heat generated by the heating member, thereby melting and accommodating the fuse member. By doing this, it is possible to block the connection between the upper electrode for the fuse and the connection terminal.

According to an embodiment of the present invention, the flow blocking member has a shape of a dam structure surrounding the fuse member and the fuse accommodating member, and may block flow after the fuse accommodating member and the fuse member are melted. .

According to one embodiment of the present invention, the flow blocking member has an open area, the fuse member and the fuse accommodating member are positioned in the open area, and the planar area of the open area is such that the fuse member and the fuse accommodating member are positioned in the open area. It may be larger than the contact surface area of the molten bond formed by being solidified after being melted.

According to one embodiment of the present invention, the flow blocking member may be a solder resist (SR) member formed using a screen printing method.

According to one embodiment of the present invention, the flow blocking member may be a solder resist (SR) laminated member formed by using the screen printing method a plurality of times.

According to one embodiment of the present invention, the flow blocking member may include a pair of first extension elements extending across the upper electrode for the fuse; a pair of second extension elements connected to ends of the first extension elements and extending along the upper electrode for the fuse; and a third extension element connecting the first extension elements to each other and positioned on the connection terminal.

According to an embodiment of the present invention, the secondary battery charging device includes a secondary battery unit connected to a power source and charged; a voltage sensing unit sensing a voltage applied to the secondary battery unit; a switch unit electrically connected to the voltage sensing unit and opening and closing an electrical path by receiving a control signal from the voltage sensing unit; and a fuse element connected in series to the secondary battery unit and the power source. and a heating element connected to the secondary battery unit and the power source in parallel and connected to the switch unit in series to generate heat when the switch unit is turned on, thereby cutting the fuse element. Including, the fuse element may be formed of the above-described ceramic protection element.

According to the technical idea of the present invention, the ceramic protection element is a device capable of protecting the secondary battery by melting when overcurrent or overvoltage is applied during charging of the secondary battery, by forming a fuse member integrated with the upper electrode It can simplify the manufacturing process time and save cost and time. In addition, as the fuse receiving member and the flow blocking member are further included, melting in overcurrent and overvoltage can be realized reliably.

The effects of the present invention described above have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a circuit diagram of a secondary battery charging device in which a ceramic protection device is installed according to an embodiment of the present invention.
2 is an external perspective view of a ceramic protection device according to an embodiment of the present invention.
3 is a cross-sectional view of a ceramic protection element according to an embodiment of the present invention taken along line AA.
4 is a top view of a ceramic protection device according to an embodiment of the present invention.
5 is a rear view of a ceramic protection device according to an embodiment of the present invention.
6 is a schematic diagram illustrating current flow when an overvoltage is applied in the ceramic protection device of FIG. 2 according to an embodiment of the present invention.
7 is an external perspective view of a ceramic protection device according to an embodiment of the present invention.
8 is a cross-sectional view of a ceramic protection element taken along line BB according to an embodiment of the present invention.
9 is a schematic diagram illustrating current flow when an overvoltage is applied in the ceramic protection device of FIG. 7 according to an embodiment of the present invention.
10 are photographs showing states before and after fusing of the ceramic protection element of FIG. 2 according to an embodiment of the present invention.
11 are photographs showing a state after fusing according to the type of flow blocking member in the ceramic protection element of FIG. 2 according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those skilled in the art, and the following examples may be modified in many different forms, The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art. Like reference numerals throughout this specification mean like elements. Further, various elements and areas in the drawings are schematically drawn. Therefore, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

In this specification, the meaning of "electrical connection" means a connection that conducts electricity through direct contact or indirect contact through another component.

1 is a circuit diagram of a secondary battery charging device 1 in which a ceramic protection device 100 according to an embodiment of the present invention is installed.

Referring to FIG. 1 , a secondary battery charging device 1 includes a secondary battery unit 10 , a voltage sensing unit 20 , a switch unit 30 , and a protection device unit 40 . The secondary battery charging device 1 may be connected to the power source 50 and may be charged by receiving power from the power source 50 .

The secondary battery unit 10 may be electrically connected to the power source 50 and may be charged by receiving power from the power source 50 . The secondary battery unit 10 may include various secondary batteries, and may include, for example, a lithium (Li) battery.

The voltage sensing unit 20 may be connected in parallel with respect to the electrical connection between the secondary battery unit 10 and the power source 50, and may sense a voltage applied to the secondary battery unit 10. Since they are connected in parallel, the voltage sensed by the voltage sensing unit 20 is the same as the voltage applied to the secondary battery unit 10 . When the voltage sensed by the voltage sensing unit 20 is an overvoltage exceeding an allowable voltage, a control signal may be transmitted to the switch unit 30 . The voltage sensing unit 20 may be composed of an integrated circuit (IC).

The switch unit 30 may be electrically connected to the voltage sensing unit 20, receive the control signal from the voltage sensing unit 20, and perform a switch function of opening and closing an electric path to the protection element unit 40. . The switch unit 30 may include a transistor, for example, a field effect transistor (FET).

When overcurrent and/or overvoltage is applied to the secondary battery charger 1, the protection device unit 40 may perform a function of blocking it. The protection device unit 40 may include a fuse element 42 and a heating element 44 . The fuse element 42 may be connected in series with respect to the secondary battery unit 10 and the power source 50 . The heating element 44 may be connected in parallel to the secondary battery unit 10 and the power source 50 . The heating element 44 may be connected to the switch unit 30 in series, and when the switch unit 30 is turned on, heat may be generated and the fuse element 42 may be blown. The protection device unit 40 may correspond to the ceramic protection device 100 described below.

Hereinafter, an operating method of the secondary battery charging device 1 will be described.

When the current and voltage applied to the secondary battery charging device 1 from the power source 50 are within the allowable current and/or allowable voltage allowed by the secondary battery charging device 1, power is supplied from the power source 50 The secondary battery unit 10 may be charged.

On the other hand, if the current and voltage applied to the secondary battery charger 1 from the power source 50 is overcurrent and/or overvoltage exceeding the allowable current and/or allowable voltage allowed by the secondary battery charger 1, Charging from the power source 50 to the secondary battery unit 10 may be stopped.

When the current applied from the power supply 50 to the secondary battery charging device 1 is an overcurrent, the fuse element 42 of the protection element unit 40 is blown due to the overcurrent, and thus the power supply 50 ) and the electrical connection between the secondary battery unit 10 is blocked. Note that the electrical path through the heating element 44 is blocked by the switch unit 30 here.

When the voltage applied from the power source 50 to the secondary battery charger 1 is an overvoltage, the fuse element 42 of the protection element unit 40 is not blown by the current. In this case, the overvoltage is detected by the voltage sensing unit 20, and the voltage sensing unit 20 transmits a control signal to the switch unit 30, and accordingly the switch unit 30 turns on on). When the switch unit 30 is a transistor, the voltage sensing unit 20 applies a gate voltage to the gate terminal of the transistor. When the switch unit 30 is turned on, current flows through the heating element 44 to generate heat, and thus the fuse element 42 is blown by the generated heat. Thus, electrical connection between the power source 50 and the secondary battery unit 10 is blocked.

2 is an external perspective view of a ceramic protection device 100 according to an embodiment of the present invention. 3 is a cross-sectional view of a ceramic protection device 100 according to an embodiment of the present invention taken along line A-A. 4 is a top view of a ceramic protection device 100 according to an embodiment of the present invention. 5 is a rear view of a ceramic protection device 100 according to an embodiment of the present invention.

2 to 5, the ceramic protection device 100 includes a ceramic substrate 110, an upper electrode 120 for a fuse, a connection terminal 130, a fuse member 140, a fuse accommodating member 150, and a heating member 160 . The ceramic protection device 100 may further include a flow blocking member 170 .

Specifically, the ceramic protection device 100 includes a ceramic substrate 110; an upper electrode 120 for a fuse positioned on the ceramic substrate 110; Connection terminals 130 positioned on the ceramic substrate 110; a fuse member 140 disposed on the ceramic substrate 110 and electrically connecting the fuse upper electrode 120 and the connection terminal 130; a fuse accommodating member 150 positioned on the fuse member 140; and a heat generating member 160 disposed between the ceramic substrate 110 and the fuse member 140 and generating heat when a current is applied to cut the fuse member.

The ceramic substrate 110 may include various ceramic materials, for example, among SiO ₂ , Ba ₂ O ₃ , Al ₂ O ₃ , CaO, MgO, SrO, Li ₂ O, ZnO, TiO ₂ , and ZrO _{2 .} At least one may be included.

The upper electrode 120 for the fuse may be positioned on the upper surface of the ceramic substrate 110 . The upper electrode 120 for a fuse may include an upper electrode 121 for a first fuse and an upper electrode 122 for a second fuse. The upper electrode 121 for the first fuse and the upper electrode 122 for the second fuse may be spaced apart from each other on the upper surface 119 of the ceramic substrate 110 .

The connection terminal 130 may be located on the upper surface of the ceramic substrate 110 . The connection terminal 130 may be positioned between the upper electrode 121 for the first fuse and the upper electrode 122 for the second fuse. The connection terminal 130 may be spaced apart from the upper electrode 121 for the first fuse and the upper electrode 122 for the second fuse. The shape of the connection terminal 130 shown is exemplary, and the technical spirit of the present invention is not limited thereto. The connection terminal 130 may have various shapes capable of performing a function of electrical connection between the second upper connection pad 188 and the fuse member 140 .

The fuse member 140 may be positioned on an upper surface of the ceramic substrate 110 . The fuse member 140 may electrically connect the secondary battery unit 10 of FIG. 1 and the power source 50, and is melted at a permissible current and/or a permissible voltage or higher to separate the secondary battery unit 10 and the power supply 50. It can perform a function of electrically shorting.

The fuse member 140 is positioned on the ceramic substrate 110 and may electrically connect the fuse upper electrode 120 and the connection terminal 130 to each other. The fuse member 140 may include a first fuse member 141 and a second fuse member 142 . The first fuse member 141 may electrically connect the upper electrode 121 for the first fuse and the connection terminal 130 . The second fuse member 142 may electrically connect the upper electrode 122 for the second fuse and the connection terminal 130 .

The connection terminal 130 and the fuse member 140 may be integrally formed. Alternatively, the fuse upper electrode 120 and the fuse member 140 may be integrally formed. Alternatively, the upper electrode 120 for the fuse, the connection terminal 130, and the fuse member 140 may be integrally formed. In addition, at least any two of the fuse upper electrode 120, the connection terminal 130, and the fuse member 140 may be formed on the same plane.

The fuse upper electrode 120 , the connection terminal 130 , and the fuse member 140 may be formed on the upper surface 119 of the ceramic substrate 110 by using a screen printing method using paste.

The upper electrode 120 for the fuse, the connection terminal 130, and the fuse member 140 may include the same material. The fuse upper electrode 120 , the connection terminal 130 , and the fuse member 140 may include, for example, silver (Ag), platinum (Pt), palladium (Pd), or an alloy thereof. At least one of the fuse upper electrode 120, the connection terminal 130, and the fuse member 140 may include, for example, 0.5 wt % to 1.5 wt % platinum and the balance silver, for example. 1 weight percent platinum and the balance may include silver. As the remainder, unavoidable impurities may be further included.

Dimensions of the fuse member 140 may change according to the allowable current and allowable voltage of the ceramic protection element 100 . Since the length of the fuse member 140 is limited by the distance between the fuse upper electrode 120 and the connection terminal 130, the rated value of the ceramic protection element 100 is adjusted by adjusting the width and height of the fuse member 140. can change The fuse member 140 may have a length capable of electrically connecting the fuse upper electrode 120 and the connection terminal 130, and may have a width ranging from 100 μm to 250 μm. However, the numerical value of the width is exemplary, and the technical spirit of the present invention is not limited thereto.

The fuse accommodating member 150 may be positioned on the fuse member 140 . The fuse accommodating member 150 may include a first fuse accommodating member 151 and a second fuse accommodating member 152 . The first fuse accommodating member 151 may be positioned on the first fuse member 141 , and the second fuse accommodating member 152 may be positioned on the second fuse member 142 .

The fuse accommodating member 150 may be formed using a screen printing or soldering method. The fuse accommodating member 150 may include solder paste. The fuse accommodating member 150 may include, for example, tin (Sn), silver (Ag), and copper (Cu). The fuse accommodating member 150 may include, for example, 2 wt% to 4 wt% silver (Ag), 0.1 wt% to 1.0 wt% copper (Cu), and the balance tin (Sn). The fuse accommodating member 150 may include, for example, 3 wt% silver (Ag), 0.5 wt% copper (Cu), and 96.5 wt% tin (Sn). As the remainder, unavoidable impurities may be further included.

Since the fuse accommodating member 150 has a low melting point, it is melted by heat generated by the heating member 160, and thus the fuse member 140 is melted in a solid solution, solution, or alloyed manner. Acceptable. The fuse accommodating member 150 may melt and solidify the fuse member 140 to form a molten assembly. Such a molten compound may tend to aggregate into a spherical shape due to surface tension, and accordingly, the fuse member 140 connected between the upper electrode 120 for a fuse and the connection terminal 130 is short-circuited, and the upper electrode for a fuse is short-circuited. The connection between 120 and the connection terminal 130 may be blocked. In addition, when the fuse accommodating member 150 is melted, the fuse upper terminal 120 or the connection terminal 130 may be melted, and the short-circuit can be made more easily by this melting.

The heating member 160 may be positioned between the ceramic substrate 110 and the fuse member 140 . The heating member 160 may be formed using a screen printing method or a soldering method. The heating member 160 may be electrically connected to the power source 50 and the switch unit 30 of FIG. 1 . The heating member 160 may generate heat when an overvoltage higher than a permissible voltage is applied to the secondary battery charging device 1 of FIG. 1 , and the fuse member 140 may be blown by this heat generation. Due to the heat generation, the fuse accommodating member 150 is melted, and then the fuse member 140 is melted, so that the fuse member 140 may be blown. The heating member 160 may include various heating materials, and may include, for example, a material having a sheet resistance ranging from 1 Ω/□ to 5 Ω/□. For example, the heating member 160 may include RuO ₂ having a sheet resistance of about 2.5 Ω/□.

A protective member 162 positioned on the heating member 160 may be further included to protect the heating member 160 . The protection member 162 may be formed to cover the heating member 160 . The protection member 162 may include a material such as over glaze.

The overglaze may include, for example, 10% to 18% by weight of aluminum oxide, 5% to 10% by weight of calcium zirconate, and 40% to 55% by weight of glass. ), 15 wt % to 25 wt % of 224 trimethyl 3 hydroxyl pentaiso butylate, 1 wt % to 5 wt % ethyl cellulose, 1 wt % to 5 wt % of C.I. Pigment Green 50, 1 wt % of dimethly phthalate, and 0.5 wt % to 2 wt % of additives. The glass may include 40% to 45% by weight of silicon and 3% to 8% by weight of boron. The C.I. The pigment green 50 may include 0.8 wt% nickel oxide, 0.5 wt% cobalt oxide, and 0.1 wt% to 2 wt% zinc oxide.

The flow blocking member 170 may be positioned on the ceramic substrate 110 . The flow blocking member 170 may block the flow after the fuse member 140 and the fuse accommodating member 150 are melted.

The flow blocking member 170 may have a shape of a dam structure surrounding the fuse member 140 and the fuse accommodating member 150 to block flow after being melted. The shape of the dam structure is a structure that extends in a direction including a vertical vector component on the substrate, and functions to limit the melted flow to the inside of the structure and block outflow to the outside of the structure. Indicates the shape of a structure that can be In addition, the flow blocking member 170 has an open area, the fuse member 140 and the fuse accommodating member 150 are positioned in the open area, and the planar area of the open area is such that the fuse member 140 and the fuse accommodating member ( 150) may be larger than the contact surface area of the molten bond formed by solidification after melting. Accordingly, the molten assembly may contact the upper terminal 120 for the fuse but not the connection terminal 130, or may contact the connection terminal 130 but not the upper terminal 120 for the fuse, Accordingly, the electrical connection between the fuse upper terminal 120 and the connection terminal 130 may be cut off.

The flow blocking member 170 includes a pair of first extension elements 171 extending across the upper electrode 120 for a fuse; a pair of second extension elements 172 connected to the end of the first extension element 171 and extending along the upper electrode 120 for a fuse; and a third extension element 173 connecting the first extension elements 171 to each other and positioned on the connection terminal 130 . Specifically, the flow blocking member 170 includes a pair of first extension elements 171 extending across between the upper electrode 121 for the first fuse and the upper electrode 122 for the second fuse; a pair of second extension elements 171 connected to the end of the first extension element 171 and extending along the upper electrode 121 for the first fuse and the upper electrode 122 for the second fuse; and a third extension element 173 connecting the first extension elements 171 to each other and positioned on the connection terminal 130 . However, this is exemplary and the present invention is not limited thereto, and the flow blocking member 170 may have various shapes.

The flow blocking member 170 may include various insulators. The flow barrier member 170 may include, for example, 25% to 35% epoxy/phenolic resin, greater than 0% to 5% phenol, greater than 0% to 1% formaldehyde, 10% by weight to 20 wt% pigment, 5 wt% to 15 wt% silicon dioxide, greater than 0 wt% to 5 wt% filler, 5 wt% to 15 wt% additives, 15 wt% to 25 wt% diethylene glycol monobutyl ether, and from 5% to 10% solvent naphtha. However, these materials are exemplary and the technical spirit of the present invention is not limited thereto.

The flow blocking member 170 may be, for example, a solder resist (SR) member formed using a screen printing method. In this case, the flow blocking member 170 may be a solder resist (SR) laminated member formed by using the screen printing method multiple times, and in contrast to a single solder resist member, after the fuse member and the fuse receiving member are melted, Flow can be blocked more effectively.

11 are photographs showing a state after fusing according to the type of flow blocking member in the ceramic protection element of FIG. 2 according to an embodiment of the present invention.

Referring to the left side of FIG. 11, the solder resist (SR) single member formed by applying the screen printing method once has a height of 20 ± 5 μm, and in this case, the flow after the fuse member and the fuse receiving member are melted blocks the flow A pattern of diffusion beyond the member to the outer region (dotted line ellipse region) of the flow blocking member can be confirmed.

In contrast, referring to the right side of FIG. 11, the solder resist (SR) layered member formed by applying the screen printing method twice has a height of 30 ± 5 μm. In this case, the flow after the fuse member and the fuse receiving member are melted It can be seen that the flow blocking member is limited to the inside of the flow blocking member without passing over the flow blocking member.

A lower electrode for a fuse may be positioned on the lower surface 118 of the ceramic protection element 100 . The lower electrode for the fuse may include a lower electrode 123 for the first fuse and a lower electrode 124 for the second fuse. The lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse may be spaced apart from each other on the lower surface 118 of the ceramic substrate 110 . The lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse may be formed on the lower surface 118 of the ceramic substrate 110 by using a screen printing method. The lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse may include a conductive material, for example, a metal, such as silver (Ag) or platinum (Pt). , palladium (Pd), or an alloy thereof.

The upper electrode 121 for the first fuse and the lower electrode 123 for the first fuse may be electrically connected through the first through conductive via 125 . The upper electrode 122 for the second fuse and the lower electrode 124 for the second fuse may be electrically connected through the second through conductive via 126 .

The first through conductive via 125 and the second through conductive via 126 may be formed to penetrate the ceramic substrate 110 and be filled with a conductive material to provide a path for electrical signals. The first through conductive via 125 and the second through conductive via 126 may be electrically connected to the power source 50 of FIG. 1 . Accordingly, the fuse member 140 electrically connects the lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse through the first through conductive via 125 and the second through conductive via 126, respectively. can be connected to In addition, the upper electrode 121 for the first fuse, the upper electrode 122 for the second fuse, the lower electrode 123 for the first fuse, and the lower electrode 124 for the second fuse are the power source 50 of FIG. can be electrically connected to The first through conductive via 125 and the second through conductive via 126 may include a conductive material, for example, a metal, such as silver (Ag), platinum (Pt), Palladium (Pd), or an alloy thereof may be included.

The upper electrode 121 for the first fuse, the upper electrode 122 for the second fuse, the lower electrode 123 for the first fuse, the lower electrode 124 for the second fuse, the first through conductive via 125, The two through conductive vias 126 are illustratively configured to provide electrical connection between the fuse member 140 and an external device (not shown), but the technical spirit of the present invention is not limited thereto. For example, there is also a case where at least a part of the lower electrode 123 for the first fuse, the lower electrode 124 for the second fuse, the first through conductive via 125, and the second through conductive via 126 are omitted. Included in the technical spirit of the present invention.

The ceramic protection element 100 may further include a lower electrode 182 for an embedded connection via, an embedded connection via 184 , a first upper connection pad 186 , and a second upper connection pad 188 . The lower electrode 182 for the embedded connection via, the embedded connection via 184, the first upper connection pad 186, and the second upper connection pad 188 may include a conductive material, for example, metal. and may include, for example, silver (Ag), platinum (Pt), palladium (Pd), or an alloy thereof.

The lower electrode 182 for the built-in connection via is located on the lower surface 118 of the ceramic substrate 110 and is electrically connected to the built-in connection via 184 to connect the built-in connection via 184 to the outside, for example, FIG. It can be electrically connected to the power source 50 of. The lower electrode 182 for the built-in connection via may be electrically shorted from the lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse. The lower electrode 182 for the embedded connection via may be formed using a screen printing method.

The embedded connection via 184 may be embedded in the ceramic substrate 110 and may be formed through the ceramic substrate 110 . The built-in connection via 184 may electrically connect the outside to the heating member 160 . The built-in connection via 184 may be spaced apart from the heating member 160 so as not to overlap with the heating member 160 . Due to this separation, heat generated from the heating member 160 may not be transferred to the lower side as much as possible. Alternatively, a case in which the built-in connection via 184 and the heating member 160 are directly connected is also included in the technical spirit of the present invention.

The first upper connection pad 186 is positioned on the top surface 119 of the ceramic substrate 110 and may electrically connect the built-in connection via 184 and the heating member 160 . The first upper connection pad 186 may be formed using a screen printing method.

The second upper connection pad 188 may be positioned on the upper surface 119 of the ceramic substrate 110 and may be positioned to contact the connection terminal 130 . The second upper connection pad 188 may electrically connect the heating member 160 and the connection terminal 130 .

The built-in connection via 184 and the second upper connection pad 188 may face each other. Specifically, the built-in connection via 184 may be positioned on a first side, and the second upper connection pad 188 may be positioned on a second side opposite to the first side with respect to the heating member 160 . In addition, the second upper connection pad 188 may be positioned above the heating member 160 , and the embedded connection via 184 may be positioned below the heating member 160 .

Hereinafter, a current path of the ceramic protection device 100 in an overcurrent or overvoltage state will be described.

First, when an overcurrent flows through the ceramic protection element 100, the fuse member 140 is blown by the overcurrent. Specifically, the fuse accommodating member 150 having a low melting point is first melted by the overcurrent, and the fuse member 140 is melted by this melting, thereby shorting the connection between the fuse upper electrode 120 and the connection terminal 130. do. In the case of the overcurrent, current does not flow through the heating member 160, so heat may not be generated.

The current path at the time of the overcurrent is as follows. The overcurrent applied from the power source 50 of FIG. 1 is transmitted through the lower electrode 123 for the first fuse, the first through conductive via 125, the upper electrode 121 for the first fuse, the first fuse member 141, A current flows through the connection terminal 130, the second fuse member 142, the upper electrode 122 for the second fuse, the second through conductive via 126, and the lower electrode 124 for the second fuse. .

6 is a schematic diagram illustrating current flow when an overvoltage is applied in the ceramic protection device 100 of FIG. 2 according to an embodiment of the present invention.

Referring to FIG. 6 , current flow in the ceramic protection device 100 when an overvoltage is applied is indicated by an arrow. Specifically, when an overvoltage is applied to the ceramic protection element 100, current flows through the heating member 160 to generate heat, and the fuse member 140 is blown by the heat. Specifically, the fuse accommodating member 150 having a low melting point is first melted by the overcurrent, and the fuse member 140 is melted by this melting, thereby shorting the connection between the fuse upper electrode 120 and the connection terminal 130. do.

The current path at the time of the overvoltage is as follows. The switch unit 30 of FIG. 1 is turned on by the overvoltage, and thus current flows from the power source 50 of FIG. 1 to the heating member 160 . The current is applied to the lower electrode 182 for the built-in connection via, the first built-in connection via 184, the first upper connection pad 186, the heating member 160, the second upper connection pad 188, and the connection terminal (130). Subsequently, as a current path from the connection terminal 130 through the first fuse member 141, the upper electrode 121 for the first fuse, the first through conductive via 125, and the lower electrode 123 for the first fuse or as a current path from the connecting terminal 130 through the second fuse member 142, the upper electrode 122 for the second fuse, the second through conductive via 126, and the lower electrode 124 for the second fuse it flows

Hereinafter, a case in which the technical spirit of the present invention is applied to a ceramic protection element including a ceramic substrate composed of a plurality of ceramic sheets integrated with each other by co-firing and having a built-in heating member embedded in the ceramic substrate will be described. . A description overlapping with the above-described embodiment will be omitted.

Hereinafter, a method of manufacturing the ceramic protection element 100 according to an embodiment of the present invention will be described by way of example.

First, a ceramic substrate 110 is prepared.

A lower terminal 123 for a first fuse, a lower terminal 124 for a second fuse, and a lower terminal 182 for a built-in connection via are formed on the lower surface 118 of the ceramic substrate 110 using a screen printing method or the like. .

The first through conductive via 125 , the second through conductive via 126 , and the embedded connection via 184 penetrating the ceramic substrate 110 are formed using a screen printing method or the like. The first through-conductive via 125, the second through-conductive via 126, and the embedded connection via 184 may be formed by forming through-holes in the ceramic substrate 110 and filling the through-holes with a conductive material. . Such filling may be performed by a screen printing method or the like.

Next, a heating member 160 is formed on the upper surface 119 of the ceramic substrate 110 . The heating member 160 may be formed using a screen printing method or a soldering method.

Next, an upper electrode 121 for a first fuse, an upper electrode 122 for a second fuse, a first upper connection pad 186 and a second upper connection pad 188 are formed on the upper surface 119 of the ceramic substrate 110. is formed using a screen printing method or the like.

Subsequently, a protective member 162 covering the heating member 160 is formed on the upper surface 119 of the ceramic substrate 110 by using a screen printing method or the like.

Next, the connection terminal 130, the first fuse member 141, and the second fuse member 142 are formed on the upper surface 119 of the ceramic substrate 110 by using a screen printing method or the like.

Subsequently, a flow blocking member 170 exposing the fuse member 140 is formed on the upper surface 119 of the ceramic substrate 110 .

Subsequently, the fuse accommodating member 150 is formed on the fuse member 140 . The fuse accommodating member 150 may be formed using a soldering method or the like.

If necessary, heat treatment such as sintering may be performed on the ceramic substrate 110 and the components described above.

7 is an external perspective view of a ceramic protection device 200 according to an embodiment of the present invention. 8 is a cross-sectional view of a ceramic protection element 200 according to an embodiment of the present invention taken along line B-B.

7 and 8, the ceramic protection device 200 includes a ceramic substrate 210, an upper electrode 220 for a fuse, a connection terminal 230, a fuse member 240, a fuse accommodating member 250, and a built-in heating member 260. The ceramic protection element 200 may further include a flow blocking member 270 .

Specifically, the ceramic protection element 200 includes a ceramic substrate 210 including a first ceramic sheet 211 and a second ceramic sheet 212 integrated with each other by simultaneous firing; an upper electrode 220 for a fuse positioned on the ceramic substrate 210; a connection terminal 230 positioned on the ceramic substrate 210; a fuse member 240 electrically connecting the fuse upper electrode 220 and the connection terminal 230; a fuse accommodating member 250 positioned on the fuse member 240; and a built-in heating member 260 embedded in the ceramic substrate 210 and generating heat when a current is applied to melt the fuse member 240 .

The ceramic substrate 210 may include a plurality of ceramic sheets integrated with each other by simultaneous firing. For example, the ceramic substrate 210 may include a first ceramic sheet 211 and a second ceramic sheet 212 sequentially stacked. The first ceramic sheet 211 and the second ceramic sheet 212 may be composed of ceramic green sheets and may be integrated with each other by simultaneous firing. In addition, the first ceramic sheet 211 and the second ceramic sheet 212 may be co-fired together with components formed on their upper, lower, or both sides. Accordingly, the ceramic protection device 200 may be referred to as low temperature co-fired ceramic (LTCC). Co-firing as described above may be performed at a temperature ranging from 700 °C to 900 °C.

7 and 8 show that the thicknesses of the first ceramic sheet 211 and the second ceramic sheet 212 are substantially the same, but this is exemplary and the technical idea of the present invention is not limited thereto, and various thicknesses are possible. do. In addition, a case in which the ceramic substrate 210 is composed of more than two or more ceramic sheets is also included in the technical spirit of the present invention.

The first ceramic sheet 211 and the second ceramic sheet 212 may have very low thermal conductivity, for example, a thermal conductivity ranging from 1 W/mK to 5 W/mK. The first ceramic sheet 211 and the second ceramic sheet 212 may include, for example, a crystalline borosilicate material. The first ceramic sheet 211 and the second ceramic sheet 212 may be, for example, SiO ₂ , Ba ₂ O ₃ , Al ₂ O ₃ , CaO, MgO, SrO, Li ₂ O, ZnO, TiO ₂ , and ZrO It may include at least one of _{the two} .

The upper electrode 220 for the fuse may be positioned on the upper surface of the ceramic substrate 210 . The fuse upper electrode 220 may include a first fuse upper electrode 221 and a second fuse upper electrode 222 spaced apart from each other on the upper surface 219 of the ceramic substrate 210 .

The connection terminal 230 may be located on an upper surface of the ceramic substrate 210 . The connection terminal 230 may be positioned between the upper electrode 221 for the first fuse and the upper electrode 222 for the second fuse. The connection terminal 230 may be spaced apart from the upper electrode 221 for the first fuse and the upper electrode 222 for the second fuse. The shape of the illustrated connection terminal 230 is exemplary, and the technical spirit of the present invention is not limited thereto. The connection terminal 230 may have various shapes capable of performing a function of electrical connection between the second built-in connection via 288 and the fuse member 240 .

The fuse member 240 is positioned on the ceramic substrate 210 and may electrically connect the fuse upper electrode 220 and the connection terminal 230 . The fuse member 240 may include a first fuse member 241 and a second fuse member 242 .

The connection terminal 230 and the fuse member 240 may be integrally formed. Alternatively, the fuse upper electrode 220 and the fuse member 240 may be integrally formed. Alternatively, the upper electrode 220 for the fuse, the connection terminal 230, and the fuse member 240 may be integrally formed. In addition, at least any two of the fuse upper electrode 220, the connection terminal 230, and the fuse member 240 may be formed on the same plane.

The fuse upper electrode 220, the connection terminal 230, and the fuse member 240 are formed by a screen printing method using a paste on the upper surface 219 of the first ceramic sheet 211 of the ceramic substrate 210. can be formed using

The fuse accommodating member 250 may be positioned on the fuse member 240 . The fuse accommodating member 250 may include a first fuse accommodating member 251 and a second fuse accommodating member 252 . The fuse accommodating member 250 may be formed using a screen printing or soldering method.

The built-in heating member 260 may be embedded inside the ceramic substrate 210 and may be interposed between the plurality of ceramic sheets. The built-in heating member 260 may be interposed between the first ceramic sheet 211 and the second ceramic sheet 212 . The built-in heating member 260 may be formed using a screen printing method or a soldering method. The built-in heating member 260 may be formed by co-firing together with the plurality of ceramic sheets.

A protective member 262 positioned on the built-in heating member 260 may be further included to protect the built-in heating member 260 . The protection member 262 may be formed to cover the built-in heating member 260 . The protection member 262 may include a material such as an overglaze.

The flow blocking member 270 may be positioned on the ceramic substrate 210 . The flow blocking member 270 may block the flow after the fuse member 240 and the fuse accommodating member 250 are melted.

The flow blocking member 270 may have a shape surrounding the fuse member 240 and the fuse accommodating member 250 to block flow after being melted. In addition, the flow blocking member 270 has an open area, the fuse member 240 and the fuse accommodating member 250 are positioned in the open area, and the planar area of the open area is such that the fuse member 240 and the fuse accommodating member ( 250) may be larger than the contact surface area of the molten bond formed by solidification after melting. Accordingly, the molten assembly may contact the upper terminal 220 for the fuse but not the connection terminal 230, or may contact the connection terminal 230 but not the upper terminal 220 for the fuse, Accordingly, an electrical connection between the fuse upper terminal 220 and the connection terminal 230 may be cut off. The flow blocking member 270 includes a pair of first extension elements 271 extending across the upper electrode 220 for a fuse; a pair of second extension elements 272 connected to the end of the first extension element 271 and extending along the upper electrode 220 for a fuse; and a third extension element 273 connecting the first extension elements 271 to each other and positioned on the connection terminal 230 . However, this is exemplary and the present invention is not limited thereto, and the flow blocking member 270 may have various shapes.

A lower electrode for a fuse may be positioned on the lower surface 218 of the ceramic protection element 200 . The lower electrode for the fuse may include the lower electrode 123 for the first fuse and the lower electrode 124 for the second fuse.

The first through-conductive via 225 and the second through-conductive via 226 are formed to penetrate the ceramic substrate 210, and specifically, through the first ceramic sheet 211 and the second ceramic sheet 212. and filled with a conductive material to provide a path for electrical signals. The fuse member 240 may be electrically connected to the first fuse lower electrode 223 and the second fuse lower electrode 224 through the first through conductive via 225 and the second through conductive via 226, respectively. there is.

The ceramic protection element 200 may further include a lower electrode 282 for an embedded connection via, a first embedded connection via 284 , an embedded connection pad 286 , and a second embedded connection via 288 . The lower electrode 282 for the embedded connection via, the first embedded connection via 284, the embedded connection pad 286, and the second embedded connection via 288 may include a conductive material, such as metal. and may include, for example, silver (Ag), platinum (Pt), palladium (Pd), or an alloy thereof.

The lower electrode 282 for the embedded connection via is located on the lower surface 218 of the ceramic substrate 210, for example, is located on the lower side of the second ceramic sheet 212, and is electrically connected to the first embedded connection via 284. It is connected so that the first built-in connection via 284 can be electrically connected to the outside, for example, to the power source 50 of FIG. 1 . The lower electrode 282 for the built-in connection via may be electrically shorted from the lower electrode 223 for the first fuse and the lower electrode 224 for the second fuse. The lower electrode 282 for the embedded connection via may be formed using a screen printing method.

The first embedded connection via 284 may be embedded in the ceramic substrate 210 and may be formed through the second ceramic sheet 212 . The first built-in connection via 284 may electrically connect the outside to the built-in heating member 260 . The first built-in connection via 284 may be spaced apart from the built-in heating member 260 so as not to overlap with the built-in heating member 260 . Due to this separation, heat generated from the built-in heating member 260 may not be transferred to the lower side as much as possible. Alternatively, a case in which the first built-in connection via 284 and the built-in heating member 260 are directly connected is also included in the technical concept of the present invention.

The built-in connection pad 286 is embedded in the ceramic substrate 210 and positioned above the second ceramic sheet 212 , and may electrically connect the first built-in connection via 284 and the built-in heating member 260 . The built-in connection pads 286 may be formed using a screen printing method.

The second embedded connection via 288 may be embedded in the ceramic substrate 210 and may be formed through the first ceramic sheet 211 . The second built-in connection via 288 may be positioned to overlap the connection terminal 230 . Here, "overlapping" means a state in which at least a portion of the connection terminal 230 overlaps at least a portion of the second embedded connection via 288 when viewed from the top to the bottom of the ceramic substrate 210. . The second built-in connection via 288 may electrically connect the built-in heating member 260 and the connection terminal 230 .

The first built-in connection via 284 and the second built-in connection via 288 may be positioned to face each other. Specifically, the first built-in connection via 284 may be positioned on a first side, and the second built-in connection via 288 may be positioned on a second side opposite to the first side with respect to the built-in heating member 260. there is. In addition, the second built-in connecting via 288 may be positioned above the built-in heating member 260 and the first built-in connecting via 284 may be positioned below the built-in heating member 260 .

Hereinafter, a current path of the ceramic protection device 200 in an overcurrent or overvoltage state will be described.

A current path when an overcurrent flows in the ceramic protection element 200 is the same as described for the ceramic protection element 100 .

9 is a schematic diagram illustrating current flow when an overvoltage is applied in the ceramic protection device 200 of FIG. 7 according to an embodiment of the present invention.

Referring to FIG. 9 , current flow in the ceramic protection device 200 when an overvoltage is applied is indicated by an arrow. Specifically, when an overvoltage is applied to the ceramic protection element 200, current flows through the built-in heating member 260 to generate heat, and the fuse member 240 is blown by the heat. Specifically, the fuse accommodating member 250 having a low melting point is first melted by the overcurrent, and the fuse member 240 is melted by this melting, thereby shorting the connection between the fuse upper electrode 220 and the connection terminal 230. do.

The current path at the time of the overvoltage is as follows. The switch unit 30 of FIG. 1 is turned on by the overvoltage, and accordingly, current flows from the power source 50 of FIG. 1 to the built-in heating member 260 . The current is applied to the lower electrode 282 for the built-in connection via, the first built-in connection via 284, the built-in connection pad 286, the built-in heating member 260, the second built-in connection via 288, and the connection terminal ( 230) to flow. Subsequently, as a current path from the connection terminal 230 through the first fuse member 241, the upper electrode 221 for the first fuse, the first through conductive via 225, and the lower electrode 223 for the first fuse or as a current path from the connection terminal 230 through the second fuse member 242, the upper electrode 222 for the second fuse, the second through conductive via 226, and the lower electrode 224 for the second fuse will flow

Hereinafter, a method of manufacturing the ceramic protection element 200 according to an embodiment of the present invention will be described by way of example.

First, a first ceramic sheet 211 is prepared. Screen-printing a lower terminal 123 for a first fuse, a lower terminal 124 for a second fuse, a lower terminal 282 for a built-in connection via, and a lower terminal for a built-in connection via 284 on the first ceramic sheet 211 formed using methods, etc. In addition, the built-in connection pads 286 are formed using a screen printing method or the like. In addition, the lower ends of the first through conductive via 225 and the second through conductive via 226 are formed using a screen printing method or the like.

Subsequently, a built-in heating member 260 is formed on the first ceramic sheet 211 . The built-in heating member 260 may be formed using a screen printing method or a soldering method. Subsequently, a protective member 262 selectively covering the built-in heating member 260 is formed.

Next, a second ceramic sheet 212 is prepared and placed on the first ceramic sheet 211 .

Subsequently, the upper terminal 221 for the first fuse, the upper terminal 222 for the second fuse, the connecting terminal 230, the first fuse member 241, and the second fuse member 242 are formed on the second ceramic sheet 212. ), and the second built-in connection vias 288 are formed using a screen printing method or the like. In addition, upper ends of the first through conductive vias 225 and the second through conductive vias 226 are formed using a screen printing method or the like.

Here, the first ceramic sheet 211 and the second ceramic sheet 212 may be green sheets. Each of the first ceramic sheet 211 and the second ceramic sheet 212 may be a single sheet or a laminated sheet in which a plurality of sheets are stacked.

The first through-conductive via 225, the second through-conductive via 226, the first embedded connection via 284, and the second embedded connection via 288 form through-holes in the corresponding ceramic sheet, and It can be formed by filling with a conductive material. Such filling may be performed by a screen printing method or the like.

Subsequently, the first ceramic sheet 211 and the second ceramic sheet 212 are fired simultaneously. Various components as described above may be co-fired with the first ceramic sheet 211 and the second ceramic sheet 212 and may also be densified. The co-firing may be performed at a temperature ranging from 700 °C to 900 °C. By such co-firing, the first ceramic sheet 211 and the second ceramic sheet 212 may be configured as an integrated ceramic substrate 210 .

Subsequently, a flow blocking member 270 exposing the fuse member 240 is formed on the first ceramic sheet 211 .

Subsequently, the fuse accommodating member 250 is formed on the fuse member 240 . The fuse accommodating member 250 may be formed by soldering or the like.

10 are photographs showing states before and after fusing of the ceramic protection element of FIG. 2 according to an embodiment of the present invention.

Referring to FIG. 10 , states before and after the fuse member and the fuse accommodating member are blown by an overcurrent of 30A and an overvoltage of 15W are shown. The fuse elements had widths of 100 μm and 250 μm. The fuse member is disposed below the fuse accommodating member.

In all cases before fusing, the fuse accommodating member connects upper terminals for fuses located on both sides and connecting terminals located in the center, and it can be seen that the fuse member located on the lower side also makes this connection.

When an overcurrent or overvoltage is applied, a short circuit occurs between the connection terminal and the upper terminal for the fuse, as shown in the red dotted line area. At the time of a short circuit, the fuse accommodating member was formed into a more spherical shape and aggregated. In addition, a part of the connection terminal is also removed by the fuse accommodating member. Since the connection terminal and the fuse member are made of the same material, melting of the connection terminal occurs together with melting of the fuse member.

When an overcurrent is applied, one of the fuse members is short-circuited. It is analyzed that this short circuit is caused by heating and melting the fuse member and the fuse accommodating member based on electrical resistance due to the overcurrent. That is, in the case of the overcurrent, if one fuse member is short-circuited, the current flow is blocked, so that the overcurrent does not flow any more even if the other fuse member is not short-circuited.

When an overvoltage is applied, both fuse members are short-circuited. It is analyzed that this short-circuit is because the built-in heating member generates heat due to the overvoltage, and the fuse member and the fuse receiving member are heated and melted based on thermal conduction due to the heat generation. That is, in the case of the overvoltage, even if one fuse member is short-circuited, current flow is not interrupted, and thus other fuse members are also short-circuited. After both fuse elements are shorted, current flow is interrupted.

For reference, when a current of 15 A flows, the temperature is measured as 93.9 ° C without melting, and the standard value of 100 ° C or less is satisfied.

The technical spirit of the present invention described above is not limited to the foregoing embodiments and the accompanying drawings, and various substitutions, modifications and changes are possible within the scope of the technical spirit of the present invention. It will be clear to those skilled in the art to which it pertains.

1: secondary battery charging device, 10: secondary battery unit,
20: voltage detection unit, 30: switch unit,
40: fuse part, 42: fuse element,
44: heating element, 50: power supply,
100: ceramic protection element, 110: ceramic substrate,
118: lower surface, 119: upper surface,
120: upper electrode for fuse,
121: upper electrode for first fuse, 122: upper electrode for second fuse,
123: lower electrode for first fuse, 124: lower electrode for second fuse,
125: first through-conductive via; 126: second through-conductive via;
130: connection terminal, 140: fuse member,
141: first fuse member, 142: second fuse member,
150: fuse accommodating member,
151: first fuse accommodating member; 152: second fuse accommodating member;
160: heating member, 162: protection member,
170: flow blocking member, 171: first extension element,
172: second extension element, 173: third extension element
182: lower electrode for built-in connection via; 184: first built-in connection via;
186: first upper connection pad; 188: second upper connection pad;
200: ceramic protection element, 210: ceramic substrate,
211: first ceramic sheet, 212: second ceramic sheet,
218: lower surface, 219: upper surface,
220: upper electrode for fuse,
221: upper electrode for first fuse, 222: upper electrode for second fuse,
225: first through-conductive via, 226: second through-conductive via,
230: connection terminal, 240: fuse member,
241: first fuse member, 242: second fuse member,
250: fuse accommodating member,
251: first fuse accommodating member; 252: second fuse accommodating member;
260: built-in heating member, 262: protection member,
270: flow blocking member, 271: first extension element,
272: second extension element, 273: third extension element
282: lower electrode for built-in connection via; 284: first built-in connection via;
286: built-in connection pad; 288: second built-in connection via;

Claims (8)

ceramic substrate;
an upper electrode for a fuse positioned on the ceramic substrate;
a connection terminal positioned on the ceramic substrate;
a fuse member positioned on the ceramic substrate and electrically connecting the upper electrode for the fuse and the connection terminal;
a heat generating member disposed between the ceramic substrate and the fuse member and generating heat when a current is applied to cut the fuse member; and
A flow blocking member located on the ceramic substrate, having a shape of a dam structure surrounding the fuse member, and blocking the flow after the fuse member is melted.
ceramic protection element. According to claim 1,
A fuse accommodating member positioned on the fuse member; further comprising,
The fuse accommodating member melts due to heat generated by the heating member, and accordingly, the fuse member is melted and accommodated, thereby blocking the connection between the upper electrode for the fuse and the connection terminal.
ceramic protection element. According to claim 2,
The flow blocking member has a shape of a dam structure surrounding the fuse member and the fuse accommodating member, and blocks flow after the fuse accommodating member and the fuse member are melted;
ceramic protection element. According to claim 3,
The flow blocking member has an open area,
The fuse member and the fuse accommodating member are positioned in the open area,
The planar area of the open area is larger than the contact surface area of a molten assembly formed by melting and solidifying the fuse member and the fuse receiving member.
ceramic protection element. According to claim 1,
Characterized in that the flow blocking member is a solder resist (SR) member formed using a screen printing method,
ceramic protection element. According to claim 5,
Characterized in that the flow blocking member is a solder resist (SR) laminated member formed by using the screen printing method a plurality of times,
ceramic protection element. According to claim 1,
The flow blocking member,
a pair of first extension elements extending across the upper electrode for the fuse;
a pair of second extension elements connected to ends of the first extension elements and extending along the upper electrode for the fuse; and
A third extension element connecting the first extension elements to each other and positioned on the connection terminal;
ceramic protection element. A secondary battery unit connected to a power source and charged;
a voltage sensing unit sensing a voltage applied to the secondary battery unit;
a switch unit electrically connected to the voltage sensing unit and opening and closing an electrical path by receiving a control signal from the voltage sensing unit;
a fuse element connected in series to the secondary battery unit and the power source; and a heating element connected to the secondary battery unit and the power source in parallel and connected to the switch unit in series to generate heat when the switch unit is turned on, thereby cutting the fuse element.
including,
The fuse element is made of the ceramic protection element of any one of claims 1 to 7,
Secondary battery charging device.

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