JP2014229443A - Fuse element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse element capable of breaking a circuit reliably.SOLUTION: A fuse element 1 comprises conductor wiring 3 provided on a substrate 2. The conductor wiring 3 has a division part 3c extending in a second direction intersecting a first direction connecting a first end part 3a and a second end part 3b. A conductor part 11 composing a fusing part is arranged in the division part 3c. The conductor part 11 composing a fusing part consists of a conductor different from first and second conductor wiring parts 3A and 3B. A low melting point metal layer 14 is provided on the upper side of the conductor part 11 composing a fusing part in the division part 3c. The low melting point metal layer 14 has a melting point lower than that of the conductor part 11 composing a fusing part and, when it becomes a melt, dissolves the conductor part 11 composing a fusing part.

Description

  The present invention relates to a fuse element that melts when an overcurrent flows, and more particularly, to a fuse element that is provided with a conductor wiring having a melted portion on a substrate.

  Conventionally, various fuse elements are used to protect electronic devices from overcurrent. Patent Document 1 below discloses a fuse element in which a low melting point metal such as tin or lead is attached to a part of a fuse conductor made of metal. When an overcurrent flows, the low melting point metal melts and the melt melts the fuse conductor. Thereby, the circuit is interrupted.

JP 2009-99372 A

  A conventional fuse element using a low-melting-point metal as described in Patent Document 1 has a liquid material such as a low-melting-point metal melt or a low-melting-point metal melt melted at the fusing part. There was a risk of staying. For this reason, the circuit may not be shut off reliably.

  An object of the present invention is to provide a fuse element capable of reliably interrupting a circuit.

  The fuse element according to the present invention includes a substrate and a conductor wiring disposed on the substrate and having a first end and a second end.

  The conductor wiring has a dividing portion. The dividing portion extends in a second direction intersecting with a first direction connecting the first end portion and the second end portion. The conductor wiring portion located on the first end side of the dividing portion is the first conductor wiring portion, and the conductor wiring portion located on the second end portion side of the dividing portion is the second conductor wiring. Part.

  The fuse element according to the present invention further includes a fusing part constituting conductor part and a low melting point metal layer. The conductor part for fusing part composition is arranged in a parting part. The fusing portion constituting conductor portion is electrically connected to the first and second conductor wiring portions and is made of a conductor different from the first and second conductor wiring portions.

  The low-melting-point metal layer is provided above the fusing part constituting conductor part in the dividing part. The low melting point metal layer has a melting point lower than that of the fusing part constituting conductor part, and dissolves the fusing part constituting conductor part when it becomes a melt.

  In the fuse element according to the present invention, preferably, the first and second conductor wiring portions have first and second side edges respectively extending in a first direction, and the fusing portion constituting conductor portion is provided. However, it has come to the outer side rather than the said 1st side edge and 2nd side edge.

  In the fuse element according to the present invention, preferably, the fuse element is connected to a portion of the fusing portion constituting conductor portion that extends to the outside of the first and second side edges of the first and second conductor wiring portions. And a molten metal guiding conductor portion having a width larger than the width of the fusing portion constituting metal extending in the second direction.

  In the fuse element according to the present invention, the molten metal guiding conductor may be extended in a direction different from the second direction.

  In the fuse element according to the present invention, preferably, a plurality of fusing part constituting conductor parts are provided.

  In the fuse element according to the present invention, the extending direction of at least one fusing part constituting conductor part among the plurality of fusing part constituting conductor parts may be different from the extending direction of the remaining fusing part constituting conductor parts. Good.

  In the fuse element according to the present invention, the fusing part constituting conductor part may be extended in a direction crossing in an oblique direction with respect to the first direction.

  In the fuse element according to the present invention, when viewed in plan, the fusing part constituting conductor part may be linear.

  In the fuse element according to the present invention, when viewed in plan, the fusing part constituting conductor part may be curved.

  In the fuse element according to the present invention, preferably, the molten metal guiding conductor portion is made of a conductor having higher wettability with the low melting point metal than the first and second conductor wiring portions.

  In the fuse element according to the present invention, preferably, the low-melting-point metal layer is made of solder, and the fusing portion constituting conductor portion is made of a metal that causes solder erosion.

  In the fuse element according to the present invention, preferably, a portion of the fusing portion constituting conductor portion that extends outside the first and second side edges of the first and second conductor wiring portions is the other portion. This is a dummy conductor portion that is not electrically connected to the conductor wiring.

  According to the fuse element of the present invention, the fusing part constituting conductor is provided in the dividing part extending in the second direction, so that when the overcurrent flows, the low melting point metal and the fusing part constituting conductor are melted. The liquid or solution is surely discharged out of the dividing portion. Accordingly, it is possible to reliably cut off the current.

(A) And (b) is a top view of the fuse element which concerns on the 1st Embodiment of this invention, and sectional drawing in alignment with the BB line in (a), (c) is the principal part. It is a partial typical sectional view shown in detail. In the 1st Embodiment of this invention, it is a schematic plan view which shows the moving direction of the melt when an overcurrent flows. (A) And (b) is a low melting point when the fuse element of the first embodiment is arranged with the short side direction as the vertical direction and when the long side direction is arranged as the vertical direction. It is each front view which shows the flow direction of a metal melt. (A) And (b) is a top view of the fuse element concerning a 2nd embodiment, and a sectional view which meets a CC line in (a). (A) And (b) is a top view of the fuse element which concerns on 3rd Embodiment, and sectional drawing which follows the DD line | wire in (a).

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  1A and 1B are a plan view of a fuse element according to a first embodiment of the present invention and a cross-sectional view taken along line BB in FIG.

  The fuse element 1 has a substrate 2. The substrate 2 is made of an appropriate insulating material. Examples of such an insulating material include a low-temperature fired ceramic material mainly composed of Ba, Al, and Si, and a high-temperature fired ceramic material such as alumina. The substrate 2 may be made of glass ceramics.

  Although not particularly limited, in the present embodiment, the substrate 2 has a rectangular plate shape. The substrate 2 has a long side surface 2a and a short side surface 2b.

  Conductor wiring 3 is provided on the substrate 2. The conductor wiring 3 has a first end 3a and a second end 3b. A current flows in a direction connecting the first end 3a and the second end 3b. The first direction from the first end 3a to the second end 3b is taken as the X direction. A dividing portion 3c is provided at the center of the conductor wiring 3 so as to extend in a second direction crossing the X direction and the oblique direction. When viewed in plan, the dividing portion 3c has a linear shape as shown in FIG. The second direction, which is the direction in which this linear shape extends, intersects the X direction and the oblique direction.

  The conductor wiring portion on the first end 3a side of the dividing portion 3c is the first conductor wiring portion 3A. The conductor wiring portion on the second end 3b side of the dividing portion 3c is the second conductor wiring portion 3B. In other words, the first conductor wiring portion 3A and the second conductor wiring portion 3B are opposed to each other with a gap formed by the dividing portion 3c.

  The first conductor wiring portion 3A has a pair of side edges 3A1 and 3A2 extending in the X direction. The second conductor wiring portion 3B also has a pair of side edges 3B1 and 3B2 extending in the X direction.

  The conductor wiring 3 is made of a metal or alloy such as Cu or Al.

  The cut portion 3c is provided with a fusing portion constituting conductor portion 11. In the present embodiment, the fusing portion constituting conductor portion 11 is made of Ag. That is, it consists of a metal that dissolves when it comes into contact with a low-melting-point metal melt described later. Examples of such a metal include Ag and alloys such as Ag and Pt and Ag and Pd.

  The fusing part constituting conductor part 11 is arranged so as to electrically connect the first and second conductor wiring parts 3A and 3B on both sides in the dividing part 3c. Although schematically shown in FIGS. 1A and 1B, more specifically, as shown in FIG. 1C, in this embodiment, after forming the fusing portion constituting conductor portion 11 The first and second conductor wiring portions 3A and 3B are formed so as to run on the inner side of the fusing portion constituting conductor portion 11 from both side edges.

  After forming the first and second conductor wiring portions 3A and 3B, the fusing portion constituting conductor is formed such that both side edges of the fusing portion constituting conductor portion 11 run over the first and second conductor wiring portions 3A and 3B. The conductor portion 11 may be formed. Even in that case, the fusing part constituting conductor part 11 can be reliably electrically connected to the first and second conductor wiring parts 3A and 3B.

  In the present embodiment, the fusing part constituting conductor part 11 reaches outside the dividing part 3c. That is, in the Y direction or -Y direction orthogonal to the X direction, the fusing part constituting conductor part 11 reaches an area outside the dividing part 3c.

  Further, molten metal guiding conductor portions 12 and 13 are provided at both ends of the fusing portion constituting conductor portion 11. In the present embodiment, the molten metal guiding conductor portions 12 and 13 are formed of the same material as the fusing portion constituting conductor portion 11. However, the molten metal guiding conductors 12 and 13 can be made of an appropriate metal as long as it is a material in which a low-melting-point metal melt described later spreads. The molten metal guiding conductor portions 12 and 13 may be made of a conductor having higher wettability with the low melting point metal constituting the low melting point metal layer 14 than the first and second conductor wiring portions 3A and 3B. desirable.

  The molten metal guiding conductor portions 12 and 13 are extended in a direction different from the direction in which the fusing portion constituting conductor portion 11 extends. In the present embodiment, the molten metal guiding conductor portions 12 and 13 are extended in the X direction or the −X direction, respectively. Moreover, the width direction dimension orthogonal to the extending direction of the conductor parts 12 and 13 for molten metal induction | guidance | derivation is made larger than the width direction dimension of the conductor part 11 for a fusing part structure. Therefore, the molten metal guiding conductors 12 and 13 have a relatively large area. In addition, the width direction dimension of the conductor part 11 for a fusing part structure is a dimension of the direction orthogonal to the direction where the conductor part 11 for a fusing part structure extends.

  In the present embodiment, the fusing part constituting conductor part 11 reaches outside the dividing part 3c as described above. In other words, the fusing portion constituting conductor portion 11 extends outside the side edges of the first and second conductor wiring portions 3A and 3B extending in the first direction described above. A portion reaching the outside of the fusing portion constituting conductor portion 11 is not electrically connected to any other conductor wiring other than the conductor wiring 3 having the first and second conductor wiring portions 3A and 3B. That is, the portion reaching the outside of the fusing portion constituting conductor portion 11 is a dummy conductor portion that is not electrically connected to another conductor wiring.

  On the upper surface of the substrate 2, a low melting point metal layer 14 is provided above the fusing part constituting conductor 11. In the present embodiment, the low melting point metal layer 14 also reaches the first conductor wiring portion 3A and the second conductor wiring portion 3B. However, the low melting point metal layer 14 may be provided only on the upper surface of the fusing part constituting conductor part 11.

  Preferably, as in the present embodiment, the low melting point metal layer 14 is desirably provided so as to reach the first and second conductor wiring portions 3A and 3B on both sides. In that case, positioning in forming the low melting point metal layer 14 is facilitated.

  In the present embodiment, the low-melting-point metal layer 14 is directly provided on the upper side of the fusing part constituting conductor part 11. However, as will be described later, the low melting point metal layer 14 may be provided on the upper side of the fusing part constituting conductor part 11 indirectly, that is, with another layer interposed therebetween. Further, the low melting point metal layer 14 may be provided only on a part of the upper surface of the fusing part constituting conductor part 11.

  The low-melting-point metal layer 14 has a lower melting point than the fusing part constituting conductor 11 and can be made of an appropriate metal that dissolves the fusing part constituting conductor 11 when it becomes a melt. Examples of such metals include tin-based solders such as Sn and Ag, Sn and Ag and Cu, Sn and Cu, Sn and Sb, and bismuth solders such as Bi and Ag, Bi and Sb, and Bi and Zn. Can do. A frame-like dam 15 is provided on the upper surface of the substrate 2. The dam 15 is provided to prevent the molten low melting point metal from flowing out. Such a dam 15 can be formed of appropriate ceramics, glass, resin, or the like.

  As shown in FIG. 1B, via hole electrodes 4 and 5 are provided in the substrate 2. Terminal electrodes 6 and 7 are provided on the lower surface of the substrate 2. The upper end of the via hole electrode 4 is electrically connected to the first conductor wiring portion 3 </ b> A, and the lower end is electrically connected to the terminal electrode 6. The upper end of the via-hole electrode 5 is electrically connected to the lower surface of the second conductor wiring portion 3 </ b> B, and the lower end is electrically connected to the terminal electrode 7.

  A heating element 16 is provided in the substrate 2. The heating element 16 can be formed of, for example, a resistance heating element. As such a resistance heating element, for example, an alloy mainly containing Ni and containing at least one metal selected from Cr, Mn, Cu and Fe can be used.

  Via hole electrodes 17 and 18 are electrically connected to the heating element 16. A terminal electrode 19 is provided on the lower surface of the substrate 2. A via hole electrode 17 is electrically connected to the terminal electrode 19. On the other hand, the lower end of the via-hole electrode 18 is electrically connected to the terminal electrode 7. The terminal electrode 7 functions as a connection electrode that electrically connects the via-hole electrode 18 and the via-hole electrode 5. The via-hole electrodes 4 and 5, the terminal electrodes 6 and 7, the via-hole electrodes 17 and 18 and the terminal electrode 19 can be formed of an appropriate metal or alloy.

  Next, the operation of the fuse element 1 of this embodiment will be described. In the fuse element 1, the fuse part having the fusing part constituting conductor part 11 and the heating element 16 are connected in series between the terminal electrode 6 and the terminal electrode 19. When an overcurrent flows between the terminal electrode 6 and the terminal electrode 19, the first and second conductor wiring portions 3A and 3B, the fusing portion constituting conductor portion 11, and the low melting point metal layer 14 generate heat. In addition, the heating element 16 also generates heat, and the temperature rises significantly. As a result, the low melting point metal layer 14 is dissolved. The melt of the low melting point metal layer 14 dissolves the metal constituting the fusing part constituting conductor part 11. Accordingly, the material constituting the low-melting-point metal layer 14 and the fusing part constituting conductor part 11 becomes the liquid material A as shown by hatching in FIG. The liquid material A is guided to the outside of the dividing portion 3c, for example, along the arrow direction.

  Therefore, as shown in FIG. 3A, when the fuse element 1 is arranged so that the side surface 2b on the short side of the substrate 2 faces in the vertical direction, the liquid material A moves as indicated by an arrow. To do. That is, the liquid A moves from the dividing portion 3c to the outside and reaches the molten metal guiding conductor portion 13 side. As described above, the molten metal guiding conductor portion 13 is made of a metal in which the liquid material easily spreads and has a large area. Therefore, the liquid material is reliably guided out of the dividing portion 3c.

  When the direction shown in FIG. 3A and the vertical direction are reversed, the liquid material flows to the molten metal guiding conductor 12 side. Therefore, even in that case, the liquid A is reliably removed from the dividing portion 3c. Therefore, the current can be reliably interrupted.

  On the other hand, when the fuse element 1 is arranged such that the side surface 2a on the long side of the substrate 2 is directed in the vertical direction, the liquid material A moves as indicated by an arrow in FIG. Therefore, also in this case, the liquid material is surely discharged to the outside from the dividing portion 3c. Therefore, the current can be reliably interrupted.

  As described above, in the fuse element 1 of the present embodiment, the dividing portion 3c extends in the second direction intersecting with the X direction, and the fusing portion constituting conductor portion 11 is disposed in the dividing portion 3c. Has been. Therefore, when the substrate 2 of the fuse element 1 is arranged in a direction different from the horizontal plane, the liquid material can be reliably discharged to the outside by the action of gravity. Therefore, by using the fuse element 1, it is possible to more reliably protect the electronic circuit from overcurrent.

  As described above, the fusing part constituting conductor part 11 can be melted by the melt of the low melting point metal layer 14 to interrupt the circuit. However, in the fuse element 1 of this embodiment, the heat generation of the heating element 16 is achieved. Thus, the circuit can be interrupted by breaking the substrate 2. In other words, during overcharging, a current is passed between the terminal electrode 19 and the terminal electrode 7 by a signal from an IC or the like to cause the heating element 16 to generate heat. The substrate 2 is thermally expanded by the heat from the heating element 16. In this case, the thermal expansion coefficient of the substrate 2 is ceramic and is small. On the other hand, since the conductor wiring 3 and the fusing part constituting conductor part 11 are made of metal, the thermal expansion coefficient is large. Therefore, tensile stress acts on the upper surface side of the substrate 2 having a small thermal expansion coefficient at the interface between the substrate 2 and the conductor wiring 3 and the fusing portion constituting conductor portion 11. As a result, the substrate 2 is broken, and accordingly, the conductor wiring 3 is also broken. In this manner, the circuit can be operated to be interrupted by breakage.

  Moreover, in the said embodiment, the width | variety of the said conductor parts 12 and 13 for molten metal induction | guidance | derivation is made larger than the width | variety of the conductor part 11 for a fusing part structure. That is, the area of the molten metal guiding conductors 12 and 13 is increased. Therefore, the liquid A can be quickly moved to the molten metal guiding conductors 12 and 13.

  Further, the molten metal guiding conductors 12 and 13 are extended in a direction crossing the second direction. In particular, in the present embodiment, the molten metal guiding conductor portions 12 and 13 are extended in the X direction and the −X direction, respectively. Accordingly, even if the molten metal guiding conductors 12 and 13 having a relatively large area are provided, an increase in the size of the fuse element 1 can be suppressed.

  The molten metal guiding conductors 12 and 13 do not necessarily have a width dimension larger than the width dimension of the fusing part constituting conductor 11. Further, the molten metal guiding conductors 12 and 13 are not necessarily provided.

  4A and 4B are a plan view of the fuse element according to the second embodiment and a cross-sectional view taken along the line CC in FIG. In the fuse element 21 of the second embodiment, a plurality of dividing portions 3c, 3c are provided. And each part 3c and 3c is provided with conductor parts 11 and 11 for fusing part composition, respectively. Further, molten metal guiding conductor portions 12 and 13 are provided at both ends of each fusing portion constituting conductor portion 11.

  In other words, a plurality of fusing part constituting conductors 11 and molten metal guiding conductors 12 and 13 are provided. In other configurations, the second embodiment is the same as the first embodiment. Therefore, about the same part, suppose that the description of 1st Embodiment is used by providing the same reference number.

  When a plurality of fusing part constituting conductor parts are provided as in the second embodiment, the current may be interrupted in any one fusing part constituting conductor part 11. Therefore, the current can be cut off more reliably.

  Of the plurality of fusing part constituting conductor parts, the direction in which at least one fusing part constituting conductor part extends may be different from the direction in which at least another fusing part constituting conductor part extends (not shown). . With such a configuration, when the substrate 2 of the fuse element 1 is arranged in a direction different from the horizontal plane, the liquid material A can be more reliably discharged to the outside from the dividing portion 3c.

  5A and 5B are a plan view of the fuse element according to the third embodiment and a cross-sectional view taken along the line DD in FIG.

  In the fuse element 31 of the third embodiment, the dividing portion 3c and the fusing portion constituting conductor portion 11 are extended in the Y direction orthogonal to the X direction. The molten metal guiding conductors 12A and 13A are extended in the X direction. The ends of the melted portion constituting conductor portion 11 are connected to the vicinity of the center of the molten metal guiding conductor portions 12A and 13A.

  Thus, in the present invention, the fusing portion constituting conductor portion 11 may be extended in a direction orthogonal to the direction connecting the first and second conductor wiring portions 3A and 3B.

  However, preferably, as in the first and second embodiments, the fusing portion constituting conductor portion 11 crosses the direction connecting the first conductor wiring portion 3A and the second conductor wiring portion 3B in an oblique direction. It is desirable that Thereby, even if the fuse element is arranged in any plane different from the horizontal plane, the liquid substance can be discharged more reliably out of the dividing portion 3c.

  In addition, as shown to Fig.5 (a), the molten metal induction | guidance | derivation conductor parts 12A and 13A are both directions of X direction and -X direction seeing from the part connected with the edge part of the fusing part structure conductor part 11, respectively. It may be extended. By adopting such a configuration, the liquid A guided to the molten metal guiding conductors 12A and 13A is guided and stored in each of the regions extending in the X direction and the −X direction. Can do.

  Moreover, although the planar shape of the conductor part 11 for fusing part structure in the above-mentioned embodiment was linear, it may be curvilinear.

  In the above-described embodiment, the low melting point metal layer 14 is provided immediately above the fusing part constituting conductor 11, but the low melting point metal layer 14 and the fusing part constituting conductor 11 are provided with a low melting point. You may arrange | position the insulator layer which electrically insulates the metal layer 14 and the conductor part 11 for a fusing part structure. In the configuration in which the insulator layer is disposed, the low melting point metal layer 14 is indirectly provided on the fusing portion constituting conductor portion 11. Such an insulator layer is preferably made of an insulating material having such a property that when the low melting point metal layer 14 is melted, it is dissolved in the melt or volatilized to be removed. In that case, not only can the low melting point metal layer 14 and the fusing portion constituting conductor portion 11 be electrically insulated, but also when the low melting point metal layer 14 becomes a melt, it can be removed. it can. As such an insulating layer, for example, a layer made of rosin flux or organic acid flux can be used.

DESCRIPTION OF SYMBOLS 1 ... Fuse element 2 ... Board | substrate 2a, 2b ... Side surface 3 ... Conductor wiring 3A ... 1st conductor wiring part 3A1, 3A2, 3B1, 3B2 ... Side edge 3a ... 1st edge part 3B ... 2nd conductor wiring part 3b ... second end 3c ... divided parts 4, 5 ... via hole electrodes 6, 7 ... terminal electrode 11 ... fused part constituting conductors 12, 12A, 13, 13A ... molten metal guiding conductor part 14 ... low melting point metal layer 15 ... Dam 16 ... Heating element 17, 18 ... Via hole electrode 19 ... Terminal electrode 21 ... Fuse element 31 ... Fuse element

Claims (12)

A substrate,
A conductor wiring disposed on the substrate and having a first end and a second end;
The conductor wiring has a dividing portion extending in a second direction intersecting with a first direction connecting the first end portion and the second end portion, and the first end of the dividing portion The conductor wiring part located on the part side is the first conductor wiring part, the conductor wiring part located on the second end side of the dividing part is the second conductor wiring part,
A fusing part constituting conductor that is disposed in the dividing part, is electrically connected to the first and second conductor wiring parts, and is made of a conductor different from the first and second conductor wiring parts. And
In the dividing part, provided above the fusing part constituting conductor part, and having a melting point lower than that of the fusing part constituting conductor part, the fusing part constituting conductor part is dissolved when it becomes a melt. A fuse element further comprising a low melting point metal layer.   The first and second conductor wiring portions have first and second side edges extending in a first direction, respectively, and the fusing portion constituting conductor portion is formed by the first side edge and the second side edge. The fuse element according to claim 1, wherein the fuse element extends to an outer side than a side edge of the fuse element.   The fusing part that is connected to a part of the fusing part constituting conductor part that extends to the outside of the first and second side edges of the first and second conductor wiring parts and extends in the second direction. The fuse element according to claim 2, further comprising a molten metal guiding conductor portion having a width larger than the width of the constituent conductor portion.   The fuse element according to claim 3, wherein the molten metal guiding conductor portion extends in a direction different from the second direction.   The fuse element according to any one of claims 1 to 4, wherein a plurality of fusing part constituting conductor parts are provided.   The fuse element according to claim 5, wherein an extending direction of at least one fusing part constituting conductor part among the plurality of fusing part constituting conductor parts is different from an extending direction of the remaining fusing part constituting conductor parts.   The fuse element according to any one of claims 1 to 6, wherein the fusing portion constituting conductor portion is extended in a direction crossing in an oblique direction with respect to the first direction.   The fuse element according to any one of claims 1 to 7, wherein, when seen in a plan view, the fusing part constituting conductor part is linear.   The fuse element of any one of Claims 1-7 whose conductor part for a fusing part structure is curvilinear when planarly viewed.   The fuse according to any one of claims 1 to 9, wherein the molten metal guiding conductor portion is made of a conductor having higher wettability with the low melting point metal than the first and second conductor wiring portions. element.   The fuse element according to any one of claims 1 to 10, wherein the low-melting-point metal layer is made of solder, and the fusing part constituting conductor part is made of a metal that causes solder erosion.   Of the conductor part for forming the fusing part, the part extending outside the first and second side edges of the first and second conductor wiring parts is not electrically connected to the other conductor wiring. The fuse element of any one of Claims 2-4 which is a dummy conductor part.

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