JP2017174592A - Protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection element excellent in fast fusing property, by transmitting heat from an electrical heating element efficiently to a fuse element.SOLUTION: A fuse element 1 includes an insulating substrate 2, a first surface electrode 3 and a second surface electrode 4 provided on a surface 2a of the insulating substrate oppositely to each other, an electrical heating element 5, a heating element extraction electrode 6 connected electrically with the electrical heating element, a fuse element 7 connected over the first surface electrode, second surface electrode and heating element extraction electrode, and melting and shutting off by heating of the electrical heating element, a first back electrode 3a and a second back electrode provided on the back of the insulating substrate, and a first side conductive part 3b and a second side conductive part 4b which are formed on the lateral faces 2c, 2d, 2e of the insulating substrate, connecting the first and second surface electrodes with the first and second back electrodes respectively, and connecting, between the surface and back of the insulating substrate, the first and second surface electrodes with the first and second back electrodes.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a protective element that is mounted on a current path, and blows a fuse element by heating with a heater when a current exceeding a rating flows to interrupt the current path.

  Conventionally, when a current exceeding the rating flows, a protection element is used that melts the fuse element by heating with a heater and interrupts the current path. Such a protective element is formed on a functional chip in which an electrode and a fuse element are mounted on an insulating substrate, and a surface-mounting type is known in which this chip is mounted on a circuit board.

  In the protective element as described above, the fuse element is blown by heating by energizing the heater based on the signal from the external circuit, so it can be used like a switch that cuts off the current path at the timing based on the control of the external circuit Is possible. Such a protection element is used as a protection circuit for a secondary battery such as a lithium ion battery.

  In recent years, there has been an increase in the number of devices requiring a high current output for applications of secondary batteries such as lithium-ion batteries, such as electric assist bicycles and power tools, and the rated current of the protection circuit has increased, so that a fuse that can withstand large currents. Elements have come to be used.

  In the technique described in Patent Document 1, a protection element using a fuse element capable of handling a large current is disclosed.

Japanese Patent Laying-Open No. 2015-035281

  However, in the technique described in Patent Document 1, a current path that conducts from the front surface to the back surface of the insulating substrate is not clearly shown, but in order to cope with a large current, only the conductive path on the side surface of the insulating substrate is used. The resistance value is large, and it is necessary to reduce the resistance value by forming a through hole directly connecting the front and back of the insulating substrate and a current path in which the through hole is filled with a conductor.

  In the technique described in Patent Document 1, when a through-hole that directly connects the front and back of an insulating substrate or a current path in which the inside of the through-hole is filled with a conductor is formed, the heat from the heater generates this current. Diffusing through the path, it becomes difficult to concentrate and transfer heat to the fuse element, and the quick fusing property of the fuse element is deteriorated.

  Therefore, an object of the present invention is to provide a protective element that can cope with a large current, efficiently transfers heat from a heater to a fuse element without hindering downsizing, and is excellent in quick fusing property.

  In order to solve the above-described problems, a protection element according to the present invention includes an insulating substrate, a first surface electrode and a second surface electrode provided on the surface of the insulating substrate so as to face each other, and a heating element. And a heating element extraction electrode electrically connected to the heating element, a first surface electrode, a second surface electrode, and a heating element extraction electrode connected to the heating element and melted by heating of the heating element. And a fuse element for cutting off a current path between the second surface electrode, a first back electrode and a second back electrode provided on the back surface of the insulating substrate, and a side surface of the insulating substrate. The front surface electrode and the second front surface electrode are connected to the first back surface electrode and the second back surface electrode, respectively, and the first front surface electrode, the second front surface electrode, and the first surface electrode are connected between the front surface and the back surface of the insulating substrate. All of the electrodes connecting the back electrode and the second back electrode of Those comprising a first side surface conductive portion and the second side surface conductor portion constituting the route.

  In order to solve the above-described problem, a protective element according to the present invention includes an insulating substrate, a first surface electrode and a second surface electrode provided on the surface of the insulating substrate so as to face each other, A heating element, a heating element extraction electrode electrically connected to the heating element, a first surface electrode, a second surface electrode, and a heating element extraction electrode are connected to the heating element and melted by heating the heating element. A fuse element that cuts off a current path between the front surface electrode and the second front surface electrode, a first back surface electrode and a second back surface electrode provided on the back surface of the insulating substrate, and a hole penetrating the insulating substrate are formed. First through-hole conductive layers that connect the first front-surface electrode and the second front-surface electrode to the first back-surface electrode and the second back-surface electrode, respectively, and serve as a conductive path between the front surface and the back surface of the insulating substrate. And a second through-conductive portion, the first table Electrode and the second surface electrode is one which has a first surface protrusion protruding in a region in contact with the first through conducting portions and the second through conducting portions and the second surface protrusions, respectively.

  According to the present invention, by arranging the current path that conducts the front and back surfaces of the insulating substrate only on the side surface of the insulating substrate, the heat from the heater is concentrated in the fuse element without diffusing into the through holes. Can be transmitted, and the quick fusing property of the fuse element can be improved. In addition, even when a through-hole is provided with a current path that conducts between the front and back surfaces of the insulating substrate as a through-hole, only the surface protrusions that protrude from the surface electrode to the periphery of the current path are formed to reduce the area of the surface electrode. By reducing the size, heat diffusion to the surface electrode can be prevented, heat can be concentrated and transferred to the fuse element, and the quick fusing property of the fuse element can be improved.

FIG. 1 is a plan view illustrating a fuse element according to a first embodiment with a fuse element seen through. 2 is a cross-sectional view taken along line A-A ′ shown in FIG. 1. FIG. 3 is a schematic diagram for explaining the shape of the first side surface conductive portion, and is a plan view of the first surface electrode as viewed from above, and FIG. 3 (A) shows a semicircular shape. 3 (B) shows a rectangular groove shape, FIG. 3 (C) shows a semi-long hole shape, and FIG. 3 (D) shows a wave groove shape. FIG. 4 is an equivalent circuit diagram for explaining the circuit configuration of the fuse element. FIG. 4A shows a state before the operation of the fuse element, and FIG. 4B shows a state where the fuse element is melted after the operation of the fuse element. Shows the state. FIG. 5 is a plan view showing a state in which the fuse element in FIG. 1 is activated and the fuse element is melted. FIG. 6 is a cross-sectional view taken along the line A-A ′ shown in FIG. 5. FIG. 7 is a plan view illustrating the fuse element according to the first modified example with a perspective view of the fuse element. FIG. 8 is a plan view illustrating the fuse element according to the second modification example with the fuse element seen through. FIG. 9 is a plan view illustrating a fuse element according to a third modification with a fuse element seen through. FIG. 10 is a plan view illustrating the fuse element according to the fourth modification example with the fuse element seen through. FIG. 11 is a plan view illustrating the fuse element according to the second embodiment with the fuse element seen through. FIG. 12 is a plan view of the fuse element in FIG. 11 viewed from the back side. 13 is a cross-sectional view taken along line A-A ′ shown in FIG. 11. FIG. 14 is a plan view showing a state where the fuse element in FIG. 11 is activated and the fuse element is melted. 15 is a cross-sectional view taken along line A-A ′ shown in FIG. 14.

  Hereinafter, a fuse element as a protection element to which the present invention is applied will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[First Embodiment]
As shown in FIGS. 1 and 2, the fuse element 1 according to the first embodiment is surface-mounted by reflow on a circuit board such as a protection circuit of a lithium ion secondary battery, for example, so that the lithium ion secondary The fuse element 7 is incorporated on the charge / discharge path of the battery.

  When a large current exceeding the rating of the fuse element 1 flows, this protection circuit cuts off the current path by fusing the fuse element 7 by self-heating (Joule heat). In addition, the protection circuit is configured such that the heating element 5 is energized at a predetermined timing by a current control element provided on a circuit board or the like on which the fuse element 1 is mounted, and the fuse element 7 is blown by the heat generated by the heating element 5. The current path can be interrupted. FIG. 1 is a plan view showing the fuse element 1 with the case omitted, and FIG. 2 is a cross-sectional view of the fuse element 1.

[Fuse element]
As shown in FIGS. 1 and 2, the fuse element 1 includes an insulating substrate 2, a first surface electrode 3 and a second surface electrode 4 provided on the surface 2 a of the insulating substrate 2 so as to face each other. The heating element 5, the heating element extraction electrode 6 electrically connected to the heating element 5, the first surface electrode 3, the second surface electrode 4, and the heating element extraction electrode 6 are connected across the heating element 5. A fuse element 7 which is melted by heating and interrupts a current path between the first surface electrode 3 and the second surface electrode 4, and the first back surface electrode 3 a and the second back surface electrode 2 a provided on the back surface 2 b of the insulating substrate 2. The back electrode 4a is formed on the side surface of the insulating substrate 2, and the first surface electrode 3 and the second surface electrode 4 are connected to the first back electrode 3a and the second back electrode 3b, respectively. 2 between the front surface 2a and the back surface 2b of the first surface electrode 3 and the second surface electrode 2 And a a surface electrode 4 and the first back electrode 3a and the second first side conductive portion 3b and the second side conductive portion 4b constituting all of the current path for connecting the back electrode 3b.

  In addition, the fuse element 1 is provided on the surface 2a of the insulating substrate 2 on both ends of the heating element 5 so as to cover the heating element 5 and prevent contact between the heating element 5 and the heating element extraction electrode 6. A first heating element electrode 10 and a second heating element electrode 11 are provided. One end of the heating element extraction electrode 6 is connected to the second heating element electrode 11, and the other end is connected to the middle part of the fuse element 7.

  In addition, the fuse element 1 is formed on the side surface of the insulating substrate 2 and the third back electrode 10a provided on the back surface 2b of the insulating substrate 2, and the first heating element electrode 10 and the third back electrode 10a are connected to each other. A third side surface conductive portion 10b that is connected and serves as all the conductive paths between the front surface 2a and the back surface 2b of the insulating substrate 2 is provided.

  Here, all the current paths between the front surface 2a and the back surface 2b of the insulating substrate 2 are the first front surface electrode 3, the second front surface electrode 4, the first heating element electrode 10, and the first back surface. This represents current paths connecting the electrode 3a, the second back electrode 4a, and the third back electrode 10a. Therefore, it represents that the current path is formed only on the side surface of the insulating substrate 2. In other words, the fuse element 1 has a structure in which no current path is formed except for the side surface of the insulating substrate 2.

  Specifically, the first side surface conductive portion 3b, the second side surface conductive portion 4b, and the third side surface conductive portion 10b in the fuse element 1 are respectively the first side surface 2c, the second side surface 2d, and the second side surface conductive portion 10b. It is provided on the third side surface 2e.

  Since the fuse element 1 has no current path other than the side surface of the insulating substrate 2 and does not have a current path such as a through hole in the central portion of the insulating substrate, the heat generated from the heating element 5 is generated at the center of the insulating substrate. The fuse element 7 is configured to be concentrated and overheated without being diffused by a through hole or the like of the portion.

[Insulated substrate]
The insulating substrate 2 is formed in a square shape by an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, the insulating substrate 2 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board. The insulating substrate 2 has side surfaces facing each other as a first side surface 2c and a second side surface 2d, and the remaining side surfaces being a third side surface 2e and a fourth side surface 2f facing each other.

[First surface electrode and second surface electrode]
The first surface electrode 3 and the second surface electrode 4 are opened by being spaced apart from each other in the vicinity of opposite side edges on the surface 2a of the insulating substrate 2, and the fuse element 7 is mounted. Thus, they are electrically connected via the fuse element 7. In addition, the first surface electrode 3 and the second surface electrode 4 cause a large current exceeding the rating to flow through the fuse element 1 and the fuse element 7 is melted by self-heating (Joule heat), or the heating element 5 is energized. When the heat is generated and the fuse element 7 is melted, the current path is interrupted.

  As shown in FIGS. 1 and 2, the first surface electrode 3 and the second surface electrode 4 are respectively connected to the first side surface 2c and the second side surface 2d of the insulating substrate 2 via half-through holes. Are connected to the first back electrode 3a and the second back electrode 4a, which are external connection electrodes provided on the back surface 2b. The fuse element 1 is connected to a circuit board on which an external circuit is formed via the first back electrode 3a and the second back electrode 4a, and constitutes a part of a current path of the external circuit. Therefore, the half through holes provided in the first side surface 2c and the second side surface 2d constitute the first side surface conductive portion 3b and the second side surface conductive portion 4b.

  The first surface electrode 3 and the second surface electrode 4 can be formed using a general electrode material such as Cu or Ag. In addition, a coating such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is formed on the surfaces of the first surface electrode 3 and the second surface electrode 4 by a known method such as plating. Preferably it is coated. Thereby, the fuse element 1 can prevent the oxidation of the first surface electrode 3 and the second surface electrode 4, and can prevent the fluctuation of the rating due to the increase of the conduction resistance.

  Further, when the fuse element 1 is reflow-mounted, when the low melting point metal layer is formed on the outer layer of the connecting solder or the fuse element 7 to which the fuse element 7 is connected, the low melting point metal is melted to cause the first. It is possible to prevent the surface electrode 3 and the second surface electrode 4 from being corroded (soldered).

[Heating element]
The heating element 5 is a conductive member that generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru, Cu, Ag, or an alloy containing these as main components. The heating element 5 is obtained by mixing a powdery body of these alloys, compositions, or compounds with a resin binder or the like, forming a paste on the insulating substrate 2 using a screen printing technique, and firing it. Etc. can be formed. The heating element 5 has one end connected to the first heating element electrode 10 and the other end connected to the second heating element electrode 11.

  In the fuse element 1, an insulating material 9 is disposed so as to cover a heating element 5 formed on the surface 2 a of the insulating substrate 2, and a heating element extraction electrode is provided so as to face the heating element 5 through the insulator 9. 6 is formed. In order to efficiently transfer the heat of the heating element 5 to the fuse element 7, an insulator may be laminated between the heating element 5 and the insulating substrate 2. As the insulator 9, for example, a glass material can be used.

  One end of the heating element lead-out electrode 6 is connected to the second heating element electrode 11 and is continuous with one end of the heating element 5 through the second heating element electrode 11. The second heating element electrode 11 is formed on the surface 2a side of the insulating substrate 2, and the first heating element electrode 10 is formed on the third side surface 2e side from the surface 2a side of the insulating substrate 2. . The first heating element electrode 10 is connected to the third back surface electrode 10a formed on the back surface 2b of the insulating substrate 2 through a half through hole formed on the third side surface 2e. Therefore, the half through hole formed in the third side surface 2e constitutes the third side surface conductive portion 10b.

  When the fuse element 1 is mounted on the circuit board, the heating element 5 is connected to an external circuit formed on the circuit board via the third back electrode 10a. The heating element 5 is energized through the third back electrode 10a at a predetermined timing to interrupt the current path of the external circuit, and generates heat, whereby the first surface electrode 3 and the second surface electrode 4 are connected. The connected fuse element 7 can be blown. Further, the heating element 5 stops its heat generation because the fuse element 7 is melted to cut off its own current path.

[Heating element extraction electrode]
The heating element extraction electrode 6 can be formed using a general electrode material such as Cu or Ag. Moreover, it is preferable that a coating film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is coated on the surface of the heating element extraction electrode 6 by a known method such as plating.

[First heating element electrode and second heating element electrode]
The first heating element electrode 10 and the second heating element electrode 11 are opened by disposing the neighboring side edges in the vicinity of each other on the surface 2a of the insulating substrate 2, and the heating element 5 is mounted. By doing so, they are electrically connected via the heating element 5.

  The first heating element electrode 10 and the second heating element electrode 11 can be formed using a general electrode material such as Cu or Ag. Further, on the surfaces of the first heating element electrode 10 and the second heating element electrode 11, a coating such as Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating or the like is known such as plating treatment. It is preferably coated by a technique.

  Here, the first back surface electrode 3a and the first side surface conductive portion 3b can be formed of the same material as that of the first surface electrode 3, and the second back surface electrode 4a and the second side surface conductive portion 3b. The portion 4b can be formed of the same material as that of the second front surface electrode 4, and the third back surface electrode 10a and the third side surface conductive portion 10b are formed of the same material as that of the first heating element electrode 10. Shall be able to.

[Fuse element]
The fuse element 7 is made of a material that is quickly melted by the heat generated by the heating element 5, and for example, a low melting point metal such as solder or Pb-free solder whose main component is Sn can be suitably used.

  The fuse element 7 may be made of a high melting point metal such as In, Pb, Ag, Cu, or an alloy containing any of these as a main component, or the inner layer is a low melting point metal layer and the outer layer is a high melting point. It may be a laminate of a low melting point metal and a high melting point metal such as a metal layer. By including the high melting point metal and the low melting point metal, even when the reflow temperature exceeds the melting point of the low melting point metal when the fuse element 1 is reflow mounted, Outflow to the outside can be suppressed and the shape of the fuse element 7 can be maintained. In addition, even when fusing, the low melting point metal melts, and the high melting point metal is eroded (soldered), so that the fusing can be quickly performed at a temperature lower than the melting point of the high melting point metal.

  The fuse element 7 is connected to the heating element extraction electrode 6, the first surface electrode 3, and the second surface electrode 4 by solder or the like. The fuse element 7 can be easily connected by reflow soldering. When the fuse element 7 is mounted on the heating element extraction electrode 6, the fuse element 7 is superimposed on the heating element extraction electrode 6 and also on the heating element 5. Also, the fuse element 7 connected between the first surface electrode 3 and the second surface electrode 4 is fused between the first surface electrode 3 and the second surface electrode 4, and the first surface electrode 3 The gap between the electrode 3 and the second surface electrode 4 is blocked. That is, the fuse element 7 is supported at the center by the heating element extraction electrode 6 and at the center supported by the heating element extraction electrode 6 as a fusing part.

  The fuse element 7 is coated with a flux (not shown) to prevent oxidation and improve wettability. By maintaining the flux, the fuse element 7 can be blown quickly by preventing oxidation of the fuse element 7 and an increase in fusing temperature due to oxidation, suppressing fluctuations in fusing characteristics.

[Side conductive part]
Here, the 1st side surface conductive part 3b, the 2nd side surface conductive part 4b, and the 2nd side surface conductive part 10b are demonstrated in detail.

  The 1st side surface conductive part 3b, the 2nd side surface conductive part 4b, and the 2nd side surface conductive part 10b can be formed using common electrode materials, such as Cu and Ag. Further, a coating such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is formed on the surfaces of the first side surface conductive portion 3b, the second side surface conductive portion 4b, and the second side surface conductive portion 10b. However, it is preferably coated by a known method such as plating.

  Next, the shape of the 1st side surface conductive part 3b, the 2nd side surface conductive part 4b, and the 2nd side surface conductive part 10b is demonstrated based on FIG. In the following description, only the first side surface conductive portion 3b will be described. However, the second side surface conductive portion 4b and the second side surface conductive portion 10b can have the same shape, and thus description thereof is omitted. To do.

  The first side surface conductive portion 3b shown in FIG. 3A is formed by adding a semicircular cutout to the insulating substrate 2 to form a recess, and patterning a conductive material in the recess. The first side surface conductive portion 3b is a so-called half-through hole, and electrically connects the first surface electrode 3 and the first back surface electrode 3b between the front surface 2a and the back surface 2b of the insulating substrate 2. .

  The first side surface conductive portion 3b shown in FIG. 3A is provided with a circular through hole between individual insulating substrates adjacent to each other when the insulating substrate 2 is cut out from a mother substrate (not shown). By cutting out the insulating substrate, it can be formed as a semicircular recess. The through-hole is easy to manufacture because it can be easily created by providing a cylindrical projection on a mold for forming the mother substrate.

  Also, the first side surface conductive portion 3b can be formed in other shapes. For example, the first side surface conductive portion 3c shown in FIG. Is formed by patterning a conductive material in the recess. The first side surface conductive portion 3c electrically connects the first front surface electrode 3 and the first back surface electrode 3b between the front surface 2a and the back surface 2b of the insulating substrate 2.

  The first side surface conductive portion 3c shown in FIG. 3B is provided with a rectangular through hole between individual insulating substrates adjacent to each other when the insulating substrate 2 is cut out from a mother substrate (not shown). By cutting out the insulating substrate, it can be formed as a rectangular groove-shaped recess. The through-hole can be easily created by providing a rectangular prism-shaped protrusion on a mold for forming the mother substrate, and thus is easy to manufacture.

  The first side surface conductive portion 3c shown in FIG. 3 (B) has an area of a recess in the first side surface 2c of the insulating substrate 2 as compared with the first side surface conductive portion 3b shown in FIG. 3 (A). As a result, the width of the current path can be widened to reduce the electric resistance value, which is suitable for dealing with a large current.

  In addition, the first side surface conductive portion 3b can be formed in another shape. For example, the first side surface conductive portion 3d shown in FIG. A recess is formed by adding a notch, and a conductive material is patterned in the recess. The first side surface conductive portion 3d electrically connects the first front surface electrode 3 and the first back surface electrode 3b between the front surface 2a and the back surface 2b of the insulating substrate 2.

  The first side surface conductive portion 3d shown in FIG. 3C is provided with an elongated through hole between individual insulating substrates adjacent to each other when the insulating substrate 2 is cut out from a mother substrate (not shown). By cutting out each insulating substrate, it can be formed as a recess having a semi-long hole shape. The through-hole can be easily produced by providing a columnar protrusion corresponding to the rectangular elongated hole shape on the mold for forming the mother substrate.

  The first side surface conductive portion 3d shown in FIG. 3C has an area of a recess on the first side surface 2c of the insulating substrate 2 as compared with the first side surface conductive portion 3b shown in FIG. As a result, the width of the current path can be widened to reduce the electric resistance value, which is suitable for dealing with a large current.

  It is also possible to form the first side surface conductive portion 3b in another shape. For example, the first side surface conductive portion 3e shown in FIG. A recess is formed by adding a notch, and a conductive material is patterned in the recess. The first side surface conductive portion 3e electrically connects the first surface electrode 3 and the first back surface electrode 3b between the front surface 2a and the back surface 2b of the insulating substrate 2.

  The first side surface conductive portion 3e shown in FIG. 3 (D) is provided with a corrugated long hole-shaped through hole between adjacent individual insulating substrates when the insulating substrate 2 is cut out from a mother substrate (not shown). By cutting out each insulating substrate at the boundary, it can be formed as a wave groove-shaped recess. The through-hole can be easily produced by providing a columnar protrusion corresponding to the corrugated long hole shape on the mold for forming the mother substrate.

  The first side surface conductive portion 3e shown in FIG. 3 (D) has a concave area on the first side surface 2c of the insulating substrate 2 as compared with the first side surface conductive portion 3b shown in FIG. 3 (A). As a result, the width of the current path can be widened to reduce the electric resistance value, which is suitable for dealing with a large current.

  Summarizing the shape of each recess described above, the side surface of the insulating substrate 2 is configured by a non-planar surface including a curved surface, so that the area of the recess can be increased, and as a result, the width of the current path is increased to increase the electric resistance value. Therefore, it can be said that it is suitable for dealing with a large current.

  Note that the fuse element 1 realizes a small and highly rated protective element. For example, the dimensions of the insulating substrate 2 are as small as about 2 to 3 mm × 1 to 2 mm, and the resistance value is 0.5 to 1mΩ, 50-60A rating and higher rating are achieved. Of course, the present invention can be applied to protective elements having all sizes, resistance values, and current ratings. In this embodiment, the size of the insulating substrate 2 is 2.7 mm × 1.8 mm.

  The fuse element 1 is provided with a cover member (not shown) that protects the inside and prevents the melted fuse element 7 from scattering on the surface 2 a of the insulating substrate 2. The cover member has a side wall mounted on the surface 2 a of the insulating substrate 2 and a top surface constituting the upper surface of the fuse element 1. This cover member can be formed using, for example, an insulating member such as a thermoplastic plastic, ceramics, or a glass epoxy substrate. Since the characteristic structure of the present invention is the internal structure of the cover member, reference to the cover member is omitted in the following description.

[Circuit configuration]
Here, a circuit configuration of the fuse element 1 and an interruption operation of the energization path will be described. As shown in FIGS. 1 and 4A, the fuse element 1 has a fuse element 7 connected from the first surface electrode 3 to the second surface electrode 4, and a heating element in the middle of the fuse element 7. An extraction electrode 6 is connected. The heating element extraction electrode 6 is connected to the side opposite to the side connected to the fuse element 7 in the order of the second heating element electrode 11, the heating element 5, and the first heating element electrode 10. Accordingly, the fuse element 1 includes the first side surface conductive portion 3b, the second side surface conductive portion 4b, and the second side electrode from the first surface electrode 3, the second surface electrode 4, and the first heating element electrode 10, respectively. It can be said that this is a three-terminal element having the first back electrode 3a, the second back electrode 4a, and the third back electrode 10a connected via the side conductive portion 10b as external terminals.

  The fuse element 1 is configured such that the current of the main circuit flows from the first surface electrode 3 toward the second surface electrode 4, and generates heat when current flows from the first heating element electrode 10. As shown in FIGS. 5, 6, and 4 (B), the body 5 generates heat, the fuse element 7 is melted, the melt 7 a is agglomerated on the heating element extraction electrode 6, and the fuse element 7 is cut. Thereby, in the fuse element 1, the current path between the first surface electrode 3 and the second surface electrode 4 is blocked, and the current path to the heating element 5 is also blocked.

[Modification 1]
Next, a modified example of the fuse element 1 described above will be described. Moreover, about the site | part substantially equivalent to the fuse element 1 demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted and a difference is demonstrated. The equivalent circuit is the same as that described with reference to FIG.

As shown in FIG. 7, in the fuse element 20 according to the first modification, the first surface electrode 3 extends to the fourth side surface 2f of the insulating substrate 2, and the first side surface conductive portion 3b is not provided. The side surface conductive portion 3b ₁ is provided on the fourth side surface 2f of the insulating substrate 2, the second surface electrode 4 extends to the third side surface 2e of the insulating substrate 2, and the second side surface conductive portion 4b is not provided. A configuration in which the second side surface conductive portion 4b ₁ is provided on the third side surface 2e of the insulating substrate 2, and the first side surface conductive portion 3b ₁ and the second side surface conductive portion 4b ₁ are arranged at diagonal positions on the insulating substrate 2. It is what.

Although not shown, the fuse element 20 includes a first side surface conductive portion in which the first back surface electrode 3a extends to the fourth side surface 2f of the insulating substrate 2 on the back surface 2b side of the insulating substrate 2. 3b ₁ , the second back surface electrode 4a extends to the third side surface 2e of the insulating substrate 2 and is connected to the second side surface conductive portion 4b ₁ .

In the fuse element 20, since the first side surface conductive portion 3 b ₁ and the second side surface conductive portion 4 b ₁ are disposed at a position far from the heat generating element 5, the effect of preventing the diffusion of heat from the heat generating element 5 is enhanced, and the fuse element 20 It becomes easy to concentrate heat on the element 7.

[Modification 2]
A modification of the fuse element 1 described above will be described. Moreover, about the site | part substantially equivalent to the fuse element 1 demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted and a difference is demonstrated. The equivalent circuit is the same as that described with reference to FIG.

As shown in FIG. 8, the fuse element 30 according to the modified example 2 includes the first surface electrode 3 extending to the fourth side surface 2f of the insulating substrate 2 and the first side surface conductive portion 3b. The side surface conductive portion 3b ₁ is provided on the fourth side surface 2f of the insulating substrate 2, and the second surface electrode 4 is extended to the third side surface 2e of the insulating substrate 2 while including the second side surface conductive portion 4b. a second side conductive portion 4b ₁ is provided with a third aspect 2e of the insulating substrate 2, a first side conductive portion 3b and the second side conductive portion 4b in the opposite position, the first side surface conductor portions 3b ₁ and The second side surface conductive portion 4b ₁ is arranged at a diagonal position of the insulating substrate 2.

Although not shown, the fuse element 30 includes a first side surface conductive portion in which the first back surface electrode 3a is extended to the fourth side surface 2f of the insulating substrate 2 on the back surface 2b side of the insulating substrate 2. 3b ₁ , the second back surface electrode 4a extends to the third side surface 2e of the insulating substrate 2 and is connected to the second side surface conductive portion 4b ₁ .

Since the fuse element 30 includes the first side surface conductive portion 3b ₁ and the second side surface conductive portion 4b ₁ in addition to the first side surface conductive portion 3b and the second side surface conductive portion 4b, there are a plurality of current paths. It is possible to reduce the electric resistance value of the entire current path. Therefore, the fuse element 30 can cope with a large current by reducing the electric resistance value of the current path.

[Modification 3]
A modification of the fuse element 1 described above will be described. Moreover, about the site | part substantially equivalent to the fuse element 1 demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted and a difference is demonstrated. The equivalent circuit is the same as that described with reference to FIG.

As shown in FIG. 9, the fuse element 40 according to the modification 3 has two energization paths of the first side surface conductive portion 3 b ₂ and the first side surface conductive portion 3 b ₃ on the first side surface 2 c of the insulating substrate 2. The second side surface 2d of the insulating substrate 2 is provided with two current paths of the second side surface conductive portion 4b ₂ and the second side surface conductive portion 4b ₃ , and the first side surface conductive portion 3b ₂ and the second side surface are provided. In this configuration, the conductive portion 4b ₂ is disposed at the opposite position, and the first side surface conductive portion 3b ₃ and the second side surface conductive portion 4b ₃ are disposed at the opposite position.

Although not shown, in the fuse element 40, on the back surface 2b side of the insulating substrate 2, the first back surface electrode 3a is connected to the first side surface conductive portion 3b ₂ and the first side surface conductive portion 3b _3. The second back surface electrode 4a is connected to the second side surface conductive portion 4b ₂ and the second side surface conductive portion 4b ₃ .

In the fuse element 40, the first side surface conductive portion 3b and the second side surface conductive portion 4b are respectively connected to the first side surface conductive portion 3b ₂ , the first side surface conductive portion 3b _3, and the second side surface conductive portion 4b ₂ , Since the second side conductive portion 4b _{3 has} a plurality of configurations, there are a plurality of current paths, and it is possible to reduce the electric resistance value of the entire current path. Therefore, the fuse element 40 can cope with a large current by reducing the electric resistance value of the current path.

In the fuse element 40, the first side surface conductive portion 3 b ₂ , the first side surface conductive portion 3 b _3, the second side surface conductive portion 4 b ₂ , and the second side surface conductive portion 4 b ₃ are respectively connected to the first side conductive portion ₃ b 2. Side surface 2c and second side surface 2d, that is, they are provided on the same side surface. Since the part to be cut when the insulating substrate is cut out from the mother substrate is a place where the through hole is cut out, it is possible to easily perform the cutting operation at the portion where the plurality of through holes are arranged.

[Modification 4]
A modification of the fuse element 1 described above will be described. Moreover, about the site | part substantially equivalent to the fuse element 1 demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted and a difference is demonstrated. The equivalent circuit is the same as that described with reference to FIG.

As shown in FIG. 10, in the fuse element 50 according to the modified example 4, the first surface electrode 3 is extended to the third side surface 2e of the insulating substrate 2, and the first side surface conductive portion 3b is not provided. The side surface conductive portion 3b ₄ is provided on the third side surface 2e of the insulating substrate 2, the second surface electrode 4 is extended to the third side surface 2e of the insulating substrate 2, and the second side surface conductive portion 4b is not provided. The second side surface conductive portion 4b ₄ is provided on the third side surface 2e of the insulating substrate 2, and the first side surface conductive portion 3b ₁ and the second side surface conductive portion 4b ₁ are insulated, including the third side surface conductive portion 10b. The third side surface 2e of the substrate 2, that is, the same side surface is used.

Although not shown, the fuse element 50 includes a first side surface conductive portion in which the first back surface electrode 3a extends to the third side surface 2e of the insulating substrate 2 on the back surface 2b side of the insulating substrate 2. is connected to 3b _4, the second back electrode 4a is connected to the second side conductive portion 4b ₄ is extended to the third aspect 2e of the insulating substrate 2.

In the fuse element 50, since the first side surface conductive portion 3b ₁ and the second side surface conductive portion 4b ₁ including the third side surface conductive portion 10b are arranged on the same side surface of the insulating substrate 2, the fuse element 50 is insulated from the mother substrate. Since the parting part when cutting out the substrate is a place where the through hole is cut out, it becomes possible to easily perform the cutting work.

Further, in the fuse element 50, since the first side surface conductive portion 3b ₁ and the second side surface conductive portion 4b ₁ including the third side surface conductive portion 10b are arranged on the same side surface of the insulating substrate 2, a circuit is provided. Whether the solder for connection is sucked up by the third side surface conductive portion 10b, the first side surface conductive portion 3b ₄ and the second side surface conductive portion 4b ₄ during the mounting on the board, and the electrical connection is normally performed. Since the work of visually confirming is completed only by looking at one side, the connection confirmation process can be simplified.

[Second Embodiment]
Next, a fuse element 60 according to a second embodiment will be described with reference to FIGS. Moreover, about the site | part substantially equivalent to the fuse element 1 demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted and a difference is demonstrated. The equivalent circuit is the same as that described with reference to FIG.

  When a large current exceeding the rating of the fuse element 60 flows, this protection circuit cuts off the current path by fusing the fuse element 7 by self-heating (Joule heat). In addition, the protection circuit is configured such that the heating element 5 is energized at a predetermined timing by a current control element provided on a circuit board or the like on which the fuse element 1 is mounted, and the fuse element 7 is blown by the heat generated by the heating element 5. The current path can be interrupted. 11 is a plan view showing the fuse element 60 with the case omitted. FIG. 12 is a plan view of the fuse element 60 as viewed from the back side. FIG. It is sectional drawing.

[Fuse element]
As shown in FIGS. 11 to 13, the fuse element 60 includes an insulating substrate 2, a first surface electrode 3 and a second surface electrode 4 provided on the surface 2 a of the insulating substrate 2 so as to face each other. The heating element 5, the heating element extraction electrode 6 electrically connected to the heating element 5, the first surface electrode 3, the second surface electrode 4, and the heating element extraction electrode 6 are connected across the heating element 5. A fuse element 7 which is melted by heating and interrupts a current path between the first surface electrode 3 and the second surface electrode 4, and the first back surface electrode 3 a and the second back surface electrode 2 a provided on the back surface 2 b of the insulating substrate 2. The back electrode 4a is formed as a hole penetrating the insulating substrate 2, and the first surface electrode 3 and the second surface electrode 4 are connected to the first back electrode 3a and the second back electrode 4a, respectively. The current path between the front surface 2a and the back surface 2b of the insulating substrate 2 And the first surface electrode 3 and the second surface electrode 4 are formed of the first through conductive portion 15 and the second through conductive portion. The first surface convex portion 3 f and the second surface convex portion 4 f that protrude in a region in contact with 16 are respectively provided.

  In addition, the fuse element 60 covers the heating element 5 and prevents the contact between the heating element 5 and the heating element extraction electrode 6, and the first element provided on both ends of the heating element 5 on the insulating substrate 2. A heating element electrode 10 and a second heating element electrode 11 are provided. One end of the heating element extraction electrode 6 is connected to the second heating element electrode 11, and the other end is connected to the middle part of the fuse element 7.

  In the fuse element 60, as shown in FIG. 12, the first back electrode 3a and the second back electrode 4a protrude into a region in contact with the first through conductive portion 15 and the second through conductive portion 16. The first back surface convex portion 3g and the second back surface convex portion 4g are provided.

  The fuse element 60 is formed on the side surface of the insulating substrate 2 and connects the first front surface electrode 3 and the second front surface electrode 4 to the first back surface electrode 3a and the second back surface electrode 3b, respectively. Between the front surface 2a and the back surface 2b of the board | substrate 2, it has the 1st side surface conductive part 3b and the 2nd side surface conductive part 4b used as a current path.

  Specifically, the first side surface conductive portion 3b, the second side surface conductive portion 4b, and the third side surface conductive portion 10b in the fuse element 60 are respectively connected to the first side surface 2c, the second side surface 2d, and the second side surface conductive portion 10b. It is provided on the third side surface 2e.

  Here, the first surface convex portion 3f and the second surface convex portion 4f are the rectangular portions described in the fuse element 1 described in the first embodiment with respect to the first surface electrode 3 and the second surface electrode 4. The structure formed by notching a part close | similar to the heat generating body 5 other than the area | region corresponding to the 1st penetration conductive part 15 and the 2nd penetration conductive part 16 among some shapes is represented. In other words, it can be said that the region protrudes from the main portion of the first surface electrode 3 in order to connect the first surface electrode 3 and the first penetrating conductive portion 15.

  The fuse element 60 has a current path that penetrates the insulating substrate 2 in addition to the first side surface 2c and the second side surface 2d of the insulating substrate 2, and a large current is used to reduce the electric resistance value of the entire current path. It becomes easy to cope with.

  The fuse element 60 corresponds to the first through conductive portion 15 and the second through conductive portion 16 on the side of the first surface electrode 3 and the second surface electrode 4 that is close to the heating element 5. Since the first surface convex portion 3f and the second surface convex portion 4f are formed only in the region, the heat generated from the heating element 5 is diffused to the first surface electrode 3 and the second surface electrode 4. The fuse element 7 can be concentrated and overheated.

  In addition, the fuse element 60 includes the first back surface electrode 3a and the second back surface electrode 4a on the side close to the heating element 5 in the same manner as the first surface electrode 3 and the second surface electrode 4. Since the first back surface convex portion 3g and the second front surface convex portion 4g are formed only in the region corresponding to the first through conductive portion 15 and the second through conductive portion 16, heat generated from the heating element 5 is generated. The fuse element 7 can be concentrated and overheated without diffusing to the first back electrode 3a and the second back electrode 4a.

  In the fuse element 60 according to the second embodiment, since the heating element 5 is disposed on the surface 2a of the insulating substrate 2, the heat diffusion prevention by the first surface convex portion 3f and the second surface convex portion 4f is prevented. The effect is particularly great.

  Therefore, in the fuse element in which the heating element 5 is provided on the surface 2 a of the insulating substrate 2, at least the first surface electrode 3 and the second surface electrode 4 include the first surface convex portion 3 f and the second surface electrode. It is only necessary to have the front surface convex portion 4f, and the first back surface convex portion 3g and the second back surface convex portion 4g may not be provided.

  Further, in the fuse element in which the heating element 5 is provided on the back surface 2b of the insulating substrate 2, the heat diffusion preventing effect by the first back surface convex portion 3g and the second back surface convex portion 4g is particularly large.

  Therefore, in the fuse element in which the heating element 5 is provided on the back surface 2b of the insulating substrate 2, at least the first back electrode 3a and the second back electrode 4a are provided with the first back surface protrusion 3g and the second back surface electrode. It is only necessary to have the back surface convex part 4g, and the first front surface convex part 3f and the second front surface convex part 4f may not be provided.

  Here, the first penetrating conductive portion 15 and the second penetrating conductive portion 16 are through holes, and in particular, by filling the inside of the hole with a conductive material, the electric resistance value in the entire current path. It is possible to increase the reduction effect.

  Here, when the effect of reducing the electric resistance value by the first through conductive portion 15 and the second through conductive portion 16 is high, the first side conductive portion 3b and the second side conductive portion 4b are not provided. Although a fuse element may be configured, it is preferably left as a half-through hole that sucks up the bonding solder in order to ensure the mounting state on the circuit board or the like.

  In addition, the fuse element 60 includes two first through conductive portions 15 and two second through conductive portions 16. Therefore, the fuse element 60 includes the first front surface convex portion 3f, the second front surface convex portion 4f, the first back surface convex portion 3g, and the first back surface conductive portion 3g corresponding to the first through conductive portion 15 and the second through conductive portion 16. Two back surface convex portions 4g are also provided.

  The number of the first through-conductive portions 15 and the second through-conductive portions 16 and the shape and diameter of the through-holes can be changed as appropriate in adjusting the electric resistance value of the current path. It is not limited to description of.

[Summary]
As described above, the fuse element described as the first embodiment, each modification, and the second embodiment prevents thermal diffusion from the heating element to other than the fuse element, and the resistance value of the entire conductive path is increased. Therefore, it is possible to reduce the size of the device while accommodating a large current.

  In addition, as a structure of the fuse element in the first embodiment, a structure in which the above-described modified examples are appropriately combined may be used. For example, the shape, the number, the arrangement position, and the like of the side surface conductive portions are arbitrarily combined. Needless to say.

  1, 20, 30, 40, 50, 60 fuse element, 2 insulating substrate, 2a surface, 2b back surface, 2c first side surface, 2d second side surface, 2e third side surface, 2f fourth side surface, 3 first 1 surface electrode, 3a 1st back surface electrode, 3b, 3c, 3d, 3e 1st side surface conductive part, 3f 1st surface convex part, 3g 1st back surface convex part, 4 2nd surface electrode, 4a 2nd back surface electrode, 4b, 4c, 4d, 4e 2nd side surface conductive part, 4f 2nd surface convex part, 4g 2nd back surface convex part, 5 heating element, 6 heating element extraction electrode, 7 fuse element, 7a Melt, 9 Insulator, 10 First heating element electrode, 10a Third back electrode, 10b Third side conductive part, 11 Second heating element electrode, 15 First through conductive part, 16 Second Penetration conductive part

Claims (13)

An insulating substrate;
A first surface electrode and a second surface electrode provided on the surface of the insulating substrate so as to face each other;
A heating element;
A heating element extraction electrode electrically connected to the heating element;
A current path between the first surface electrode and the second surface electrode is connected across the first surface electrode, the second surface electrode, and the heating element extraction electrode and melts by heating the heating element. A fuse element that shuts off
A first back electrode and a second back electrode provided on the back surface of the insulating substrate;
Formed on the side surface of the insulating substrate, connecting the first surface electrode and the second surface electrode to the first back surface electrode and the second back surface electrode, respectively; The first side surface conductive portion and the second side electrode constituting all the current paths connecting the first surface electrode and the second surface electrode to the first back electrode and the second back electrode A protective element comprising two side surface conductive parts.   The insulating substrate is provided with a recess in a side surface corresponding to the first surface electrode and the second surface electrode, and the first side surface conductive portion and the second side surface conductive portion are formed in the recess. The protective element according to claim 1.   The protection element according to claim 2, wherein the first side surface conductive portion and the second side surface conductive portion are provided on side surfaces of the insulating substrate facing each other.   The protection element according to claim 3, wherein the first side surface conductive portion and the second side surface conductive portion are provided at positions facing each other.   The protection element according to claim 3, wherein the first side surface conductive portion and the second side surface conductive portion are provided at positions offset from positions facing each other.   The protection element according to claim 2, wherein the first side surface conductive portion and the second side surface conductive portion are provided on the same side surface of the insulating substrate.   The protection element according to any one of claims 2 to 6, wherein a plurality of the first side surface conductive portions or the second surface electrodes are provided.   The protection element according to claim 2, wherein the recess is a half-through hole.   The protection element according to any one of claims 2 to 8, wherein the recess includes a side surface of the insulating substrate formed by a non-planar surface including a curved surface. An insulating substrate;
A first surface electrode and a second surface electrode provided on the surface of the insulating substrate so as to face each other;
A heating element;
A heating element extraction electrode electrically connected to the heating element;
The first surface electrode, the second surface electrode, and the heating element extraction electrode are connected to each other and melted by heating the heating element, and a current path between the first surface electrode and the second surface electrode is formed. A fuse element to shut off;
A first back electrode and a second back electrode provided on the back surface of the insulating substrate;
Formed as a hole penetrating the insulating substrate, connecting the first surface electrode and the second surface electrode to the first back electrode and the second back electrode, respectively, A first through-conductive portion and a second through-conductive portion serving as a current path between the back surface and the back surface,
The first surface electrode and the second surface electrode have a first surface convex portion and a second surface convex portion, respectively, protruding in regions contacting the first through conductive portion and the second through conductive portion. Having a protective element.   The first back surface electrode and the second back surface electrode have a first back surface projecting portion and a second back surface projecting portion projecting in a region in contact with the first through conductive portion and the second through conductive portion, respectively. The protective element according to claim 10.   The protection element according to claim 10 or 11, wherein the first through conductive portion and the second through conductive portion are through holes.   The protective element according to claim 10 or 11, wherein the first through conductive portion and the second through conductive portion are hole-filled through holes in which the inside of the hole is filled with a conductive material.

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