JP6172287B2 - Fuse element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a fuse element used for protection of an electronic circuit and a method for manufacturing the same, and more particularly to a fuse element in which a fusing part is configured using a low melting point metal and a method for manufacturing the same.

  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

  In the fuse element as described in Patent Document 1, there is a possibility that a liquid material containing a melt of a low melting point metal and a melted fuse conductor may remain in the melted portion. For this reason, the circuit may not be shut off reliably.

  Further, in a conventional fuse element using a low melting point metal, the low melting point metal sometimes melts due to the temperature during reflow. For this reason, there has been a problem that the fuse element cannot be surface-mounted on the circuit board by the reflow method, or even if it can be surface-mounted, the fusing characteristics are changed.

  An object of the present invention is to provide a fuse element and a method for manufacturing the same, which can cut off a current more reliably and hardly cause a change in fusing characteristics during surface mounting due to reflow.

  The fuse element according to the present invention is provided so as to directly or indirectly cover a substrate, a conductor wiring provided on the substrate, and a part of the conductor wiring, and has a lower melting point than the conductor wiring. A low melting point metal layer that forms a melted portion by melting the conductor wiring, and the low melting point metal layer is made of pure Bi or a Bi-based alloy containing 80% by weight or more of Bi.

  On the specific situation with the fuse element which concerns on this invention, the resin layer provided so that the said low melting metal layer may be contacted is further provided. In this case, the fluidity of the melt in which pure Bi or Bi-based alloy is melted can be enhanced by the stirring effect by the gas generated by vaporizing the resin at the temperature at which the conductor wiring is melted. Accordingly, the fusing part can be formed more reliably and promptly. Preferably, a crystalline thermoplastic resin is used as the resin layer.

  In still another specific aspect of the fuse element according to the present invention, the resin layer is provided so as to cover at least a part of the conductor wiring.

  In still another specific aspect of the fuse element according to the present invention, the resin layer is provided so as to cover at least a part of the low melting point metal layer.

  In still another specific aspect of the fuse element according to the present invention, the conductor wiring is made of Ag or an alloy mainly composed of Ag. In this case, since the conductor wiring is likely to diffuse into pure Bi and Bi-based alloy, the fusing part can be formed more reliably.

  In still another specific aspect of the fuse element according to the present invention, an auxiliary metal provided on the substrate so as to be located at a part of a lower surface of the low melting point metal layer in a region where the low melting point metal layer is provided. A width direction edge of the conductor wiring in the width direction when the direction in which the conductor wiring extends is a first direction and the direction orthogonal to the first direction is the width direction. The auxiliary metal film extends to the outside, and the ratio of the dimension in the first direction to the dimension in the width direction of the auxiliary metal film is 0.3 or more. In this case, a pure Bi or Bi-based alloy melt quickly wets and spreads on the auxiliary metal film. Therefore, the circuit can be cut off more reliably.

  In still another specific aspect of the fuse element according to the present invention, the fuse element is provided directly or indirectly on the substrate or in the substrate, and further includes a heating element that generates heat when a current flows, The heating element is connected to a part of the conductor wiring, and the heating element is provided so as to melt the conductor wiring by heat when the heating element generates heat. In this case, when an abnormality occurs, the heat generating element can generate heat, and the low melting point metal layer can be melted by the heat generation of the heat generating element to form a fusing part. Therefore, not only can the current be interrupted when an overcurrent flows, but also the circuit can be interrupted by the heat generated by the heating element.

  In another specific aspect of the fuse element according to the present invention, the heating element is a resistor.

  In still another specific aspect of the fuse element according to the present invention, the resistor is formed of a resistance film provided on the substrate, and an insulating glass layer provided between the resistance film and the conductor wiring is further provided. Is provided.

  In still another specific aspect of the fuse element according to the present invention, the conductor wiring, the insulating glass layer, and the resistor are laminated in this order from the bottom.

  In still another specific aspect of the fuse element according to the present invention, the heating element does not overlap the low melting point metal layer.

  A method for manufacturing a fuse element according to the present invention is a method for obtaining a fuse element configured according to the present invention, and includes the following steps.

A step of providing a conductor wiring on the substrate; and on the substrate, the melting point is lower than that of the conductor wiring so as to directly or indirectly cover a part of the conductor wiring, and the conductor wiring is melted as a melt. Forming a low-melting-point metal layer that forms a fused portion by a Bi-based alloy containing 80% by weight or more of pure Bi or Bi.

  On the specific situation with the manufacturing method of the fuse element which concerns on this invention, the process of forming a resin layer so that it may contact the said low melting metal layer on the said board | substrate is further provided. Preferably, the resin layer is a crystalline thermoplastic resin.

  According to the fuse element and the manufacturing method thereof according to the present invention, since the low melting point metal layer is composed of the pure Bi or Bi base alloy having a low melting point, it is placed in a high temperature environment such as during surface mounting by reflow. Even so, the low melting point metal layer is difficult to melt. Therefore, it can be surface-mounted easily and reliably on a circuit board by reflow or the like. In addition, it is difficult for the fusing characteristics to change under a high temperature environment.

  In addition, since the low melting point metal layer is composed of the pure Bi or Bi-based alloy, a fusing part can be reliably formed when an overcurrent flows, thereby reliably blocking the current. It becomes possible to do.

FIG. 1A and FIG. 1B are a plan view of a fuse element according to the first embodiment of the present invention and a cross-sectional view taken along line BB in FIG. FIG. 2 is a cross-sectional view for explaining a state after the circuit is cut off in the fuse element according to the first embodiment of the present invention. FIG. 3 is a plan view for explaining an electrode structure provided on the substrate in the fuse element according to the first embodiment of the present invention. FIG. 4 is a plan view showing a state in which a resistor is printed on the first-layer electrode on the substrate in the fuse element according to the first embodiment of the present invention. FIG. 5 is a plan view showing a state in which an insulating glass layer is formed so as to cover the resistor in the fuse element according to the first embodiment of the present invention. FIG. 6 is a plan view showing a state in which the second electrode film is formed on the insulating glass layer in the method for manufacturing the fuse element according to the first embodiment of the present invention. FIG. 7 is a plan view showing a state in which an overcoat layer is formed in the method for manufacturing a fuse element according to the first embodiment of the present invention. FIG. 8 is a plan view of the fuse element according to the first embodiment of the present invention. FIG. 9 is a partially cutaway plan view for explaining the shape of the auxiliary metal film in the fuse element according to the first embodiment of the present invention. FIG. 10 is a schematic plan view for explaining a mode in which the low melting point metal layer moves in the fuse element according to the first embodiment of the present invention. FIG. 11A and FIG. 11B are a plan view of a modification in the case where the auxiliary metal film is not provided and a cross-sectional view taken along the line CC in FIG. 11A. 12A and 12B are a plan view for explaining a state after current interruption in the structure shown in FIG. 11 and a cross-sectional view taken along the line DD in FIG. . FIG. 13 is a plan view showing an auxiliary metal film having an extension used in the first embodiment of the present invention. 14A and 14B are a plan view showing a state where a low melting point metal layer is provided on the auxiliary metal film in the structure shown in FIG. 13, and EE in FIG. 14A. It is sectional drawing which follows a line. 15A and 15B are a plan view showing a state where the low melting point metal layer shown in FIG. 14 has moved after the current cut-off operation, and a cross-sectional view taken along line FF in FIG. 15A. It is. FIG. 16 is a plan view for explaining a preferable shape of the auxiliary metal film. FIG. 17 is a plan view showing a modification of the auxiliary metal film. FIG. 18 is a plan view showing a modification of the auxiliary metal film. FIG. 19 is a plan view showing a modification of the auxiliary metal film. FIG. 20 is a plan view showing a modification of the auxiliary metal film. FIG. 21 is a plan view of a fuse element according to the second embodiment of the present invention. 22 is a cross-sectional view taken along the line GG in FIG. 23 is a cross-sectional view showing a state after current interruption in the fuse element according to the second embodiment of the present invention, and is a cross-sectional view showing a state in the cross-sectional portion shown in FIG. FIG. 24 is a plan view showing an electrode structure provided on a substrate in manufacturing the fuse element according to the second embodiment of the present invention. FIG. 25 is a schematic plan view showing a state in which an insulating glass layer is formed on a substrate in manufacturing the fuse element of the second embodiment. FIG. 26 is a schematic plan view showing a state in which a resistor is printed on an insulating glass layer in manufacturing the fuse element according to the second embodiment. FIG. 27 is a plan view showing a state in which an overcoat layer is formed in the method for manufacturing a fuse element according to the second embodiment. FIG. 28 is a partially cutaway cross-sectional view showing a contact state between the low melting point metal layer after the low melting point metal layer is provided and the resin layer in contact with the low melting point metal layer. FIG. 29 is a plan view of a fuse element according to the third embodiment of the present invention. FIG. 30 is a plan view of a fuse element according to the fourth embodiment of the present invention. FIG. 31 is a plan view of a fuse element according to the fifth embodiment of the present invention. FIG. 32 is a schematic front view of the fuse element of the fifth embodiment. FIG. 33 is a schematic side view of the fuse element according to the fifth embodiment. FIG. 34 is a bottom view of a cap used in the fuse element of the fifth embodiment. FIG. 35 is a plan view showing a state in which the cap is removed from the fuse element of the fifth embodiment. FIG. 36 is a plan view of the main part of the fuse element showing a state before the resin layer is provided on the low melting point metal layer in manufacturing the fuse element of the fifth embodiment. FIG. 37 is a plan view of the fuse element according to the sixth embodiment. FIG. 38 is a schematic front view of the fuse element according to the sixth embodiment. FIG. 39 is a schematic side view of the fuse element according to the sixth embodiment. FIG. 40 is a bottom view of the cap of the fuse element according to the sixth embodiment. FIG. 41 is a plan view showing a state where the cap is removed from the fuse element according to the sixth embodiment. FIG. 42 is a cross-sectional view of a fuse element according to the seventh embodiment of the present invention. FIG. 43 is a plan view showing a state in which a fuse electrode is formed on a substrate in manufacturing the fuse element of the seventh embodiment. FIG. 44 is a plan view showing a state in which an insulating glass layer is formed in manufacturing the fuse element of the seventh embodiment. FIG. 45 is a plan view showing a state in which a resistance connection electrode is formed in manufacturing the fuse element according to the seventh embodiment. FIG. 46 is a schematic plan view showing a state in which a resistor is printed on the insulating glass layer in manufacturing the fuse element according to the seventh embodiment. FIG. 47 is a plan view showing a state in which an overcoat layer is formed in manufacturing the fuse element according to the seventh embodiment. FIG. 48 is a plan view showing a state in which the second conductor wiring is laminated on a part of the conductor wiring in manufacturing the fuse element of the eighth embodiment. FIG. 49 is a plan view showing a state where an electrode film including a conductor wiring is formed on a substrate in manufacturing a fuse element according to the ninth embodiment of the present invention. FIG. 50 is a plan view showing a state in which an insulating glass layer is formed in manufacturing the fuse element according to the ninth embodiment. FIG. 51 is a plan view showing a state in which a resistance connection electrode is formed in manufacturing the fuse element according to the ninth embodiment. FIG. 52 is a plan view showing a state in which a resistor is printed in manufacturing the fuse element of the ninth embodiment. FIG. 53 is a plan view showing a state in which an overcoat layer is formed in the manufacture of the ninth embodiment. FIG. 54 is a schematic plan view showing a state in which the second conductor wiring is laminated on the conductor wiring in manufacturing the fuse element according to the tenth embodiment of the present invention.

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

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

  The fuse element 1 has a substrate 2. In this embodiment, the substrate 2 is made of alumina. However, the substrate 2 can be formed of an appropriate insulating material. The substrate 2 has an upper surface 2a, a lower surface 2b, first and second end surfaces 2c and 2d, and first and second side surfaces 2e and 2f. The substrate 2 has a rectangular plate shape. However, the shape of the substrate 2 may be other than a rectangular plate shape.

  Although it does not specifically limit about the thickness of the said board | substrate 2, It is preferable to set it as about 0.2 mm-0.7 mm, and thickness reduction can be advanced by it.

  The laminated structure of the upper surface 2a of the substrate 2 will be clarified by describing the manufacturing method with reference to FIGS.

  First, as shown in FIG. 3, electrode lands 3 to 6 are formed by forming an Ag film on the upper surface 2 a of the substrate 2. The electrode lands 3 and 4 are formed so as to reach the edge formed by the first and second side surfaces 2e and 2f and the upper surface 2a, respectively. The electrode land 3 is electrically connected to the upper ends of the through-hole electrodes 7a and 7b penetrating the substrate 2. Similarly, the electrode land 4 is electrically connected to the upper ends of the through-hole electrodes 8a and 8b. The electrode land 5 is provided close to the first end surface 2c side and reaches the edge formed by the first end surface 2c and the upper surface 2a. The electrode land 6 is provided close to the second end surface 2d side, and is provided so as to reach an edge formed by the second end surface 2d and the upper surface 2a.

  The diameters of the through-hole electrodes 7a, 7b, 8a, 8b are not particularly limited, but are preferably about 0.2 mm to 0.5 mm.

  The electrode lands 3 to 6 can be formed by an appropriate conductive film forming method such as screen printing of a conductive paste. In the present embodiment, the electrode lands 3 to 6 are made of an Ag film. But you may form with metals or alloys other than Ag.

  The thickness of the electrode lands 3 to 6 is not particularly limited, but is preferably about 5 μm to 30 μm.

  Next, as shown in FIG. 4, the resistor 11 is formed so as to straddle between the electrode lands 5 and 6. A direction connecting the electrode lands 3 and 4 is a first direction, and a direction connecting the electrode lands 5 and 6 is a second direction. The resistor 11 extends in the second direction.

The resistor 11 is made of a material that generates heat when a current flows. As such a material, for example, RuO ₂ or AgPd can be used. An alloy containing Ni as a main component and containing at least one of Cr, Mn, Cu, and Fe can be preferably used. The resistor 11 can be formed, for example, by printing a resistor-containing paste by screen printing. Alternatively, the resistor 11 can be formed using another appropriate film forming method.

  The film thickness of the resistor 11 is not particularly limited, but is preferably about 5 μm to 30 μm. As a result, the thickness can be reduced and the fusing operation by heating the resistor 11 can be more effectively expressed.

  As described above, the resistor 11 electrically connects the electrode land 5 and the electrode land 6 and extends in the second direction.

  Next, an insulating glass layer 12 is formed as shown in FIG. The insulating glass layer 12 is provided so as to cover the resistor 11. In addition, the insulating glass layer 12 not only covers the resistor 11, but is provided in close contact with the upper surface 2 a of the substrate 2 in a region outside the portion where the resistor 11 is provided. As a material constituting the insulating glass layer 12, appropriate insulating glass such as glass ceramics can be used.

  Although it does not specifically limit about the thickness of the insulating glass layer 12, 5 micrometers-40 micrometers are preferable. If the thickness of the insulating glass layer 12 is within this range, it will be possible to develop a more sufficient insulating property and to prevent further reduction in thickness.

  Next, as shown in FIG. 6, a conductor wiring 13 is provided on the insulating glass layer 12 so as to connect the electrode land 3 and the electrode land 4. In the present embodiment, the conductor wiring 13 is made of an Ag film. However, the conductor wiring 13 can be formed of an appropriate metal material that causes a diffusion phenomenon by a low-melting-point metal melt described later. The conductor wiring 13 is melted by a diffusion phenomenon, which will be described later, to form a fusing part.

  Although the thickness of the conductor wiring 13 is not specifically limited, Preferably it is 5 micrometers-50 micrometers. If the thickness of the conductor wiring 13 is within this range, the function as a fuse conductor can be expressed more effectively.

  More preferably, it is 15 micrometers-20 micrometers. In order to increase the thickness of the conductor wiring, a method such as a method of repeatedly applying the conductor paste can be suitably used.

  The conductor wiring 13 has a main body portion 13a. A wide portion 13b is connected to one end side of the main body portion 13a, and a wide portion 13c is connected to the other end side. The wide portions 13b and 13c overlap the electrode lands 3 and 4, respectively. The width-direction dimensions of the wide portions 13b and 13c, that is, the dimensions along the second direction described above are made larger than the dimensions along the second direction of the main body portion 13a.

  On the other hand, in the main body 13a, auxiliary metal films 13d, 13d, 13e, 13e extending outward in the width direction are integrally provided. The auxiliary metal films 13d and 13d are provided to assist in mounting a low melting point metal layer, which will be described later, and to guide the low melting point metal melt in the second direction. The auxiliary metal films 13e and 13e perform the same function.

  The auxiliary metal films 13 d and 13 d are provided closer to the first electrode land 3 side than the center of the substrate 2. The auxiliary metal films 13 e and 13 e are provided closer to the second electrode land 4 side than the center of the substrate 2.

  Further, a connecting portion 13f is connected at the center of the main body portion 13a. The connection portion 13f is provided so as to reach the electrode land 5 from the main body portion 13a. Thereby, the main body 13 a is electrically connected to the electrode land 5. The connecting portion 13f extends in the second direction, but a metal film 14 is provided on the opposite side via the connecting portion 13f and the main body portion 13a.

  Although the metal film 14 does not need to be provided, by providing the metal film 14 on the side opposite to the connection portion 13f, it is possible to reduce variation in resistance and improve heat uniformity.

  The auxiliary metal films 13d, 13d, 13e, 13e and the connecting portion 13f are integrally provided on the conductor wiring 13 and are made of the same material. However, the auxiliary metal films 13d, 13d, 13e, 13e and the connection portion 13f may be formed of a metal material different from that of the main body portion 13a of the conductor wiring 13. Preferably, it is desirable to form the auxiliary metal films 13d, 13d, 13e, 13e, etc. integrally from the metal material constituting the conductor wiring 13 as in this embodiment.

  In the present embodiment, the auxiliary metal films 13d and 13d are provided on both sides in the width direction of the main body 13a. However, the auxiliary metal film 13d may be provided only on one side. The same applies to the auxiliary metal films 13e and 13e. However, it is preferable that auxiliary metal films 13d, 13d, 13e, and 13e are provided on both sides in the width direction, as will be apparent from the description of the operation described later.

  Next, as shown in FIG. 7, an overcoat layer 15 is formed. The overcoat layer 15 can be formed of an appropriate glass material or glass ceramic. Moreover, you may use highly heat-resistant resin, such as a liquid crystal polymer. The overcoat layer 15 is provided to prevent a low-melting-point metal melt, which will be described later, from flowing or scattering.

  The overcoat layer 15 has a rectangular frame portion 15a. The rectangular frame portion 15a has a portion extending along the first and second side surfaces 2e and 2f and a pair of portions extending in the first direction. And the connection part 15b extended in a 2nd direction is provided in the center of the rectangular frame-shaped part 15a. The connecting portion 15b is provided so as to overlap the connecting portion 13f and the metal film 14 described above. The shape of the overcoat layer may be an ellipse or the like, and the frame-like portion may have a shape that is partially open.

  The thickness of the overcoat layer 15 is not particularly limited, but is desirably in the range of 5 μm to 40 μm.

  Next, as shown in FIG. 8, a resin layer 19 is formed. In the present embodiment, the resin layer 19 is made of a crystalline thermoplastic resin such as polyethylene terephthalate. However, the resin layer 19 can be formed using an appropriate synthetic resin.

  Preferably, a material that melts at a temperature lower than that at which the low melting point metal melts and vaporizes at a temperature near which the melt of the low melting point metal melts the fuse conductor to generate gas is desirable. In that case, with the generated gas, the melt of the low melting point metal can be stirred to improve the fluidity. Therefore, the resin layer 19 is preferably made of a thermoplastic resin.

  More preferably, a crystalline thermoplastic resin is desirable. Unlike the flux, the crystalline thermoplastic resin does not vaporize at the reflow temperature. In the case of flux, there is a risk of vaporization due to the temperature at the time of reflowing and deterioration. The operating temperature of the fuse element 1 is relatively high at about 400 ° C. In this case, the flux deteriorates at a temperature considerably lower than reaching such an operating temperature. Therefore, sufficient oxide removal effect and stirring effect cannot be obtained at a temperature at which the low melting point metal layer made of conventional pure Bi or Bi-based alloy melts and melts the conductor wiring.

  On the other hand, since a crystalline thermoplastic resin has a high melting point, pure Bi or a Bi-based alloy is melted and vaporized at a temperature at which the conductor wiring is dissolved, and the melt is stirred by the generated gas. Therefore, fluidity can be effectively increased.

  Examples of the crystalline thermoplastic resin as described above include polyethylene terephthalate, polyphenylene sulfide, polyether ether ketone, and polytetrafluoroethylene.

  The resin layer 19 extends on the electrode land 3 side and the electrode land 4 side in the first direction through the connecting portion 15b of the overcoat layer 15 described above. That is, the resin layer 19 is provided so as to cover the main body 13 a of the conductor wiring 13. However, the resin layer 19 is not provided so as to cover the entire auxiliary metal films 13d, 13d, 13e, and 13e. That is, the resin layer 19 is provided so that at least a part of the auxiliary metal films 13d, 13d, 13e, and 13e is exposed.

  The thickness of the resin layer 19 is desirably 10 μm or more, more preferably in the range of 20 μm to 60 μm, in order to more effectively express the above-described effects of the resin layer 19.

  The planar shape of the resin layer 19 is not particularly limited, and the plane area is not particularly limited.

  Next, the low melting point metal layers 20 and 21 shown in FIG. The low melting point metal layers 20 and 21 are made of pure Bi or a Bi-based alloy containing 80% by weight or more of Bi. In forming the low melting point metal layer 20, a paste-like pure Bi or Bi-based alloy is printed and heated by a reflow method. This heating temperature is about 290 ° C. Therefore, the lower resin layer 19 melts during reflow. Accordingly, the resin layer 19 located below the low melting point metal layer 20 is melted and moves to both sides of the low melting point metal layer 20. Therefore, as shown in FIG. 1B, the resin layer 19 does not exist below the low melting point metal layer 20. In other words, the low melting point metal layer 20 is in direct contact with the lower conductor wiring 13. In addition, the resin layer 19 is in contact with the side surface of the low melting point metal layer 20.

  Moreover, although it does not specifically limit about the thickness of the low melting metal layers 20 and 21, In order to express the fusing operation | movement by the low melting metal layers 20 and 21 more effectively, the range of 0.07 mm-0.3 mm is preferable.

  As described above, the structure of the fuse element 1 on the substrate 2 shown in FIGS. 1A and 1B is formed.

  As shown in FIG. 1B, the electrode lands 3 and 4 are connected to the lead portions 22 and 22. The lead portions 22 and 22 reach the lower surface 2b via the side surfaces 2e and 2f of the substrate 2. The through-hole electrodes 7a and 7b and 8a and 8b described above are provided so as to electrically connect the electrode lands 3 and 4 and the portions reaching the lower surfaces of the lead portions 22 and 22.

  The lead portions 22 and 22 and the through-hole electrodes 7a, 7b, 8a, and 8b can be formed of an appropriate conductive material such as Ag.

  As described above, in the fuse element 1, the conductor wiring 13 is connected between the electrode land 3 and the electrode land 4. Low melting point metal layers 20 and 21 are provided so as to be in contact with the conductor wiring 13.

  On the other hand, the resistor 11 described above is connected between the electrode lands 5 and 6. The electrode land 5 is electrically connected to the conductor wiring 13. Therefore, the resistor 11 is electrically connected to the conductor wiring 13 in series.

  The current interruption operation by the fuse element 1 will be described.

  When an overcurrent flows between the electrode land 3 and the electrode land 4 of the fuse element 1, the conductor wiring 13 generates heat. Due to this heat generation, the low melting point metal layers 20 and 21 are melted. When the low melting point metal layers 20 and 21 are melted, the conductor wiring portions in contact with the melt of the low melting point metal layers 20 and 21 are diffused. Therefore, as shown in FIG. 2, fusing parts X and X are formed, and conduction by the conductor wiring 13 is interrupted. In this way, the electronic circuit can be protected from overcurrent.

  On the other hand, a switching element such as an FET that can take an on state in which current flows through the resistor 11 and an off state in which no current flows is connected to the resistor 11. And the detection element which detects the case where abnormality arises in an electronic circuit and the said switching element are electrically connected. When an abnormality occurs, the switching element is connected to the detection element so that the switching element is turned on by a signal from the detection element. According to this configuration, when an abnormality occurs in the electronic circuit, the switching element is turned on, and a current flows through the resistor 11. The resistor 11 generates heat when energized.

  On the other hand, the resistor 11 is disposed so as to be thermally coupled to the low melting point metal layers 20 and 21 so as to receive the heat of the resistor 11. Therefore, when the resistor 11 generates heat, the conductor wiring 13 is fused by the heat. As a result, a fusing part is formed and the current is interrupted.

  That is, the fuse element 1 can cut off the current in the above two types of operation modes. However, in the present invention, the resistor 11 may not be provided, and may be a fuse element that performs only one protective operation using the conductor wiring 13 and the low melting point metal layers 20 and 21.

  A feature of the fuse element 1 is that pure Bi or a Bi-based alloy containing 80% by weight or more of Bi is used for the low melting point metal layers 20 and 21. Therefore, not only can the melted portion be formed by diffusion to interrupt the current reliably, but the low melting point metal layers 20 and 21 are difficult to melt due to the temperature during reflow. Therefore, in the fuse element 1 using the low melting point metal layer, the fusing characteristics can be effectively prevented from changing, and the fuse element 1 suitable for surface mounting by reflow can be provided.

  Further, in the fuse element 1 of the above embodiment, the resin layer 19 is provided so as to be in contact with the low melting point metal layers 20 and 21 using the Bi based alloy containing the pure Bi or Bi of 80 wt% or more. The melt of the low melting point metal layer is stirred by the gas generated by the vaporization of the resin layer 19. Therefore, the low melting point metal layer melt moves quickly, and the melted part is reliably formed. Therefore, it is possible to interrupt the current more reliably.

  In addition, since the auxiliary metal films 13d, 13d, 13e, and 13e are provided in the present embodiment, the melt of the low-melting-point metal layer moves so as to form the fusing part more reliably. This will be described in more detail with reference to FIGS.

  FIG. 9 is a partially cutaway plan view showing auxiliary metal films 13d, 13d, 13e, and 13e connected to the conductor wiring 13 in the above embodiment. Here, the length of the auxiliary metal film 13d is L and the width is W. Here, the length L is a dimension along the second direction described above, and the width W is a dimension along the first direction described above.

  As shown in FIG. 1A, the low melting point metal layers 20 and 21 are provided to extend between the auxiliary metal films 13d and 13d on both sides and between the auxiliary metal films 13e and 13e, respectively. Therefore, as shown by the solid line in FIG. 10, the low melting point metal layers 20 and 21 extending in the second direction are formed.

  On the other hand, when the low melting point metal layers 20 and 21 are melted when an overcurrent flows, the low melting point metal layers 20 and 21 move as indicated by broken lines. In other words, the low melting point metal layer 20 moves in the W1 direction, and the low melting point metal layer 21 moves in the center in the W2 direction.

  This is due to the following reason. When the protection operation is performed, the central portion surrounded by the low melting point metal layers 20 and 21 becomes the highest temperature. On the other hand, the temperature decreases as the distance from the central portion increases. Therefore, the low melting point metal layers 20 and 21 are melted from the side facing the central portion. Diffusion occurs from the side facing the central portion. Therefore, the diffusion proceeds along the W1 direction and the W2 direction.

  In the present embodiment, since the auxiliary metal films 13d, 13d, 13e, and 13e are provided, the low melting point metal layers 20 and 21 extend in the second direction and reach both sides of the conductor wiring 13. Certainly provided. Therefore, the low melting point metal layers 20 and 21 can be quickly moved as indicated by the broken line in FIG. Thereby, formation of the melted part by diffusion can be performed reliably. This will be described in comparison with a configuration in which the auxiliary metal film is not provided.

  FIGS. 11A and 11B are plan views showing the conductor wiring 23 in a modified example having no auxiliary metal film. The conductor wiring 23 does not have an auxiliary metal film, and a low melting point metal layer 24 is provided in the center of the conductor wiring 23. In addition, although the edge part of the 1st direction both sides of the conductor wiring 23 is extended in the 2nd direction, these are the parts which overlap with the electrode lands 3 and 4 mentioned above, and form the auxiliary metal film. Not part.

  As shown in FIG. 11B, the low melting point metal layer 24 is provided so as to rise in the center of the conductor wiring 23.

  When an overcurrent flows through the conductor wiring 23, the melt of the low melting point metal layer 24 moves from the position indicated by the broken line to the position indicated by the solid line in FIG. That is, as shown in FIG. 12B, the low melting point metal layer does not exist in the center of the conductor wiring 23. Therefore, the melted low melting point metal layer 24 moves from the center in the first direction toward the outside, and a part of the conductor wiring 23 is blown out by diffusion.

  However, diffusion tends to be insufficient at both ends in the second direction indicated by the arrow X1 in FIG. Therefore, there is a possibility that the metal portion constituting the conductor wiring 23 remains in the portions indicated by the arrows X1 and X1, and the current is not cut off. In addition, the end surface vicinity part shown by arrow X1, X1 of FIG.12 (b) is a part with which the metal part remains as evident from hatching.

  On the other hand, the conductor wiring 13 shown in FIG. 13 is provided with the auxiliary metal films 13d and 13d according to the above embodiment. Here, in order to facilitate understanding, the shape is slightly different from the above embodiment, and only the pair of auxiliary metal films 13d and 13d is provided on the conductor wiring 13. In this case, as shown in FIGS. 14A and 14B, the low melting point metal layer 20 is provided so as to straddle the auxiliary metal films 13d and 13d on both sides. When an overcurrent flows and diffusion occurs, the low melting point metal layer 20 moves outward from the center side in the first direction as shown in FIGS. 15 (a) and 15 (b).

  As shown in FIG. 15B, the melted portion X2 where the conductor wiring 13 does not exist is reliably formed in the central portion. In particular, since the auxiliary metal films 13d and 13d are provided on both sides, that is, the diffusion surely proceeds on both sides in the width direction of the conductor wiring 13, that is, both ends in the second direction, and the fusing portion is reliably formed. Can do.

  Therefore, in the above-described embodiment, the presence of the auxiliary metal films 13d, 13d, 13e, and 13e can more reliably achieve the formation of the melted portion by diffusion.

  In order to more reliably form the melted portion by the auxiliary metal film, the auxiliary metal film 13d shown in FIG. 16 is used as an auxiliary shape rather than the width D of the conductor wiring 13 in the shape of the auxiliary metal film. It is preferable that the width direction dimension C including the metal films 13d and 13d is increased and C / D is set to 1.05 or more. More preferably, it is 1.20 or more.

  Further, B / D which is a ratio of the dimension B along the first direction of the auxiliary metal film 13d, that is, the width B of the auxiliary metal film 13d, and the width D which is the dimension along the second direction of the conductor wiring 13 Is preferably 0.3 or more, and more preferably 0.5 or more. Thereby, it is possible to further improve the reliability of the blocking operation by stabilizing the diffusion shape of pure Bi or Bi-based alloy and diffusion. It is also possible to ensure the insulation resistance after the shut-off operation. Further, when the width B is increased, that is, when the B / D ratio is 0.3 or more, the low melting point metal layer can be surely formed so as to reach between the auxiliary metal films 13d and 13d.

  As described above, the fact that such a result can be obtained when the ratio C / D and the ratio B / D are set to the above preferable ranges will be described based on the following experimental examples.

  Table 1 shows the result of forming a melted part at the time of overcurrent energization when the dimensions C and D in the auxiliary metal films 13d and 13d are added as shown in Table 1 below. In Table 1, the number of blows during 30 A energization indicates the number of samples in which a current of 30 A was passed through the fuse element and the current was interrupted within 1 minute.

  The symbol x in Table 1 indicates that the blocking rate is 50% or less, Δ is more than 50%, 80% or less, and ◯ is 100%.

  As apparent from Table 1, when the C / D ratio is 1.05 or more, the blocking rate is as high as 60 to 100%, and when it is 1.20 or more, the blocking rate is 100%.

  Moreover, about each fuse element which changed dimension B and D shown in FIG. 16 as shown in following Table 2, it supplied with the electric current of 30 A similarly to the above, and performed the fusing test. The results are shown in Table 2 below.

  The evaluation symbol x in Table 2 indicates that the blocking rate is 70% or less, Δ indicates that it exceeds 70% and is 90% or less, and ◯ indicates that it is 100%.

  As can be seen from Table 2, when B / D is 0.3 or more, the blocking rate is 90% or more, and when B / D is 0.5 or more, it is 100%.

  In the above embodiment, the auxiliary metal films 13d, 13d, 13e, and 13e protruding outward from the conductor wiring 13 in the second direction are shown, but the shape of the auxiliary metal film is not particularly limited.

  For example, the auxiliary metal film 13h shown in FIG. 17 may be used. The auxiliary metal film 13h has a relatively narrow width detail extending outward from the side of the conductor wiring 13, and a wide width portion provided at the tip of the width detail. The conductor wiring 13 is provided with notches 13g and 13g adjacent to the portion where the auxiliary metal film 13h is provided. By providing the notches 13g and 13g, a portion in which the width dimension D ′ of the conductor wiring 13 is narrower than other conductor wiring portions is provided. As a result, the fusing at the conductor wiring portion located between the notches 13g and 13g can be more reliably performed.

  Further, as shown in FIG. 18, auxiliary metal films 13 i and 13 i may be provided separately from the conductor wiring 13. As shown in FIG. 19, the shapes of the auxiliary metal film 13j on one side of the conductor wiring 13 and the auxiliary metal film 13k on the other side may be asymmetric. Further, as shown in FIG. 20, the auxiliary metal films 13l and 13m connected to the conductor wiring 13 may have a planar shape other than a rectangle. Here, the outer peripheral edges of the auxiliary metal films 13l and 13m are configured by curves. Thus, the shape of the auxiliary metal film is not particularly limited.

  In the first embodiment, the resistor 11 is used. However, instead of the resistor 11, an appropriate heating element that generates heat when a current flows may be used. As such a heating element, for example, an IC that generates heat when a current flows and various electronic component elements can be used. Further, the resistor 11 is not necessarily required to be a resistance film formed by printing as described above.

[Second Embodiment]
FIG. 21 is a plan view of a fuse element according to the second embodiment of the present invention, and FIG. 22 is a cross-sectional view taken along the line GG in FIG.

  The fuse element 31 has a substrate 32. The substrate 32 is made of an insulating material such as alumina. The substrate 32 has a rectangular plate shape. The laminated structure on the upper surface 32a of the substrate 32 will be clarified by describing the manufacturing method with reference to FIGS.

  First, as shown in FIG. 24, a conductor film 33 and an electrode land 34 are formed by forming a metal film such as an Ag film on the upper surface 32 a of the substrate 32. The conductor wiring 33 is extended in a direction connecting the side surface 32e and the side surface 32f of the substrate 32. An electrode land 34 is provided on the first end face 32c side. On the other hand, a protruding portion 35 is connected to the conductor wiring 33 so as to protrude to the side opposite to the side where the electrode land 34 is provided. The tip of the protruding portion 35 is a connecting portion 35a. The connection part 35a is located on the side close to the second end face 32d. The protruding portion 35 is formed of the same material as that of the conductor wiring 33 in the same process.

  The electrode land 34 is formed so as to reach the lower surface 32 b through the first end surface 32 c of the substrate 32.

  One end of the conductor wiring 33 is provided so as to reach the lower surface 32b through the side surface 32e. Similarly, the other end of the conductor wiring 33 is formed so as to reach the lower surface 32b via the side surface 32f. The structure in which the conductor wiring 33 reaches the lower surface 32b is shown in the sectional view of FIG.

  Next, as shown in FIG. 25, an insulating glass layer 36 is formed so as to cross the center in the length direction of the conductor wiring 33. The insulating glass layer 36 is made of the same material as the insulating glass layer 12 shown in FIG. Here, the insulating glass layer 36 is provided so as to extend from the electrode land 34 to the rectangular connecting portion 35 a at the tip of the protruding portion 35.

  Next, as shown in FIG. 26, a resistor 37 as a heating element is provided on the insulating glass layer 36. The resistor 37 can be formed in the same manner as the resistor 11 of the first embodiment.

  The resistor 37 is formed to be narrower than the insulating glass layer 36. Electrical insulation between the conductor wiring 33 and the resistor 37 is achieved by the insulating glass layer 36. In the present embodiment, on the upper surface 32a of the substrate 32, the conductor wiring 33, the insulating glass layer 36, and the resistor 37 are laminated in this order from the bottom.

  One end of the resistor 37 is joined to the electrode land 34. The other end of the resistor 37 is joined to the connection portion 35a. Therefore, the resistor 37 is connected between the electrode land 34 and the connecting portion 35a. Further, the other end of the resistor 37 is electrically connected to the conductor wiring 33.

  In the fuse element 31 of this embodiment, the electrode land 34 and one end and the other end of the conductor wiring 33 are terminals that are electrically connected to the outside. That is, a three-terminal fuse element 31 is configured.

  Next, as shown in FIG. 27, an overcoat layer 38 is formed. The overcoat layer 38 can be formed of the same material as the overcoat layer 15 in the first embodiment. The overcoat layer 38 includes a rectangular frame portion 38a and a partition portion 38b. The partition part 38b extends in the direction in which the resistor 37 extends in the center of the opening of the rectangular frame part 38a. Thereby, the opening is partitioned from the openings 38c and 38d. The partition portion 38 b is sized to cover the lower resistor 37. Therefore, as shown in FIG. 27, when viewed in plan, the resistor 37 is hidden by the partition portion 38b.

  Next, the resin layer which becomes the origin of the resin layers 39a-39c shown in FIG. 21 is formed. That is, a rectangular planar resin layer is formed as in the first embodiment. The rectangular resin layer occupies a region covering the resin layer 39a to the resin layer 39c in FIG. The resin layers 39a to 39c are made of a crystalline thermoplastic resin such as polyethylene terephthalate. However, the resin layers 39 a to 39 c can be formed using an appropriate synthetic resin in the same manner as the resin layer 19.

  After forming the resin layer, the low melting point metal layers 40 and 41 are formed as in the case of the first embodiment. The low melting point metal layers 40 and 41 are made of pure Bi or Bi based alloy containing 80% by weight or more of Bi similarly to the low melting point metal layers 20 and 21 of the first embodiment.

  In forming the low melting point metal layers 40 and 41, a paste-like metal or the above alloy is printed and heated by a reflow method. This heating temperature is about 290 ° C. And the low melting-point metal layers 40 and 41 are provided on the resin layer mentioned above. Therefore, the resin layer portion below the low melting point metal layers 40 and 41 is melted during reflow. Therefore, the resin layer located below the low melting point metal layers 40 and 41 is melted and located on both sides of the low melting point metal layers 40 and 41. In this way, the resin layers 39a to 39c are formed.

  FIG. 28 is an enlarged view of a portion where the low melting point metal layer 40 is located between the resin layer 39a and the resin layer 39b formed as described above. As shown in FIG. 28, as a result of the resin layer being pushed away by the low melting point metal layer 40, resin layers 39 a and 39 b are formed on both sides of the low melting point metal layer 40. The resin layers 39a and 39b have a fillet-like shape in which a part of the resin layer crawls up on the side surface of the low melting point metal layer 40. Therefore, the resin layers 39 a and 39 b are in contact with the side surface of the low melting point metal layer 40.

  As described above, the fuse element 31 of the second embodiment can be obtained.

  In manufacturing the fuse element 31, the electrode land 34 for connection to the outside and the conductor wiring 33 as a fuse conductor can be formed of the same material in the same process. Therefore, the manufacturing process can be simplified as compared with the first embodiment.

  Also in the fuse element 31, the current is cut off in the same manner as the fuse element 1 of the first embodiment. That is, when an overcurrent flows through the conductor wiring 33, the conductor wiring 33 generates heat. Due to this heat generation, the low melting point metal layers 40 and 41 are melted. As a result, the conductor wiring portion diffuses into the melt of the low melting point metal layers 40 and 41. Therefore, as shown in FIG. 23, fusing parts X1 and X1 are formed. Therefore, the conduction by the conductor wiring 33 is interrupted.

  On the other hand, when a current flows through the resistor 37, the resistor 37 generates heat. In the present embodiment, the low melting point metal layers 40 and 41 are arranged on the side of the resistor 37. Below the resistor 37, the conductor wiring 33 exists. The conductor wiring 33 having high thermal conductivity is in contact with the low melting point metal layers 40 and 41 in a large area. On the other hand, the insulating glass layer 36 is not so thick. Therefore, the heat generated in the resistor 37 is quickly transmitted to the conductor wiring 33 having high thermal conductivity and further transferred to the low melting point metal layers 40 and 41. Accordingly, the low melting point metal layers 40 and 41 are melted to form a fusing part similar to the above.

  Therefore, also in the fuse element 31 of the present embodiment, the current can be interrupted in two types of operation modes, similarly to the fuse element 1 of the first embodiment.

  The resin layers 39a to 39c are in contact with the low melting point metal layers 40 and 41. Therefore, the melt of the low melting point metal layers 40 and 41 is agitated by the gas generated by the vaporization of the resin layers 39a to 39c. Therefore, a fusing part can be formed more promptly and reliably.

  In the present embodiment, the low melting point metal layers 40 and 41 do not overlap with the resistor 37 in plan view as described above. Therefore, the thickness can be reduced as compared with the first embodiment. This is because only the conductor wiring 33 exists below the low melting point metal layers 40 and 41, and the insulating glass layer and the resistor do not exist.

  The resistor 37 is provided on the substrate 32 via a part of the conductor wiring 33 and the insulating glass layer 36. That is, the resistor 37 is indirectly provided on the substrate 32.

[Third Embodiment]
FIG. 29 is a plan view of a fuse element according to the third embodiment of the present invention. The fuse element 51 of the present embodiment corresponds to a modification of the first embodiment. That is, the low melting point metal layers 20A and 21A have protrusions 20a and 21a extending toward the heat generation center, respectively. Accordingly, the breaking operation can be accelerated as compared with the fuse element 1 of the first embodiment.

  The fuse element 51 is configured in the same manner as the fuse element 1 except that the protruding portions 20a and 21a are provided. Therefore, the same effect as that of the first embodiment can be obtained.

[Fourth Embodiment]
FIG. 30 is a plan view showing a fuse element 52 according to the fourth embodiment. The fuse element 52 of the fourth embodiment also corresponds to a modification of the fuse element 1 of the first embodiment. Here, the low-melting-point metal layers 20B and 21B are expanded so as to cover the entire area of the exposed conductor wiring. That is, extension portions 20b and 21b are further provided on the side opposite to the protruding portions 20a and 21a shown in FIG. Note that there is a possibility that Bi does not spread over the entire upper surface of the exposed conductor wiring due to the surface tension of the Bi melt used in the low melting point metal layers 20B and 21B. Therefore, a part of the lower conductor wiring may be exposed.

  In the fuse element 52 of the fourth embodiment, since the areas of the low melting point metal layers 20B and 21B are increased as described above, the thickness of the low melting point metal layers 20B and 21B can be reduced. Accordingly, it is possible to reduce the height. The fuse element 52 is otherwise the same as the first embodiment and the third embodiment, and therefore has the same effects as the first and third embodiments.

[Fifth Embodiment and Sixth Embodiment]
In the following, an embodiment having a structure with a cap attached will be described.

  FIG. 31 is a plan view of a fuse element according to the fifth embodiment of the present invention. In the fuse element 61, a cap 63 is fixed on the fuse element body 62. The fuse element body 62 is configured in the same manner as the fuse element 31 of the second embodiment described above. That is, the laminated structure shown in FIG. 35 is formed on the substrate 62A. In FIG. 35, the low melting point metal layers 65 and 66 are provided so as to be in contact with the resin layer 68. The low melting point metal layers 65 and 66 are disposed in the opening of the overcoat layer 67. Although not clearly shown in FIG. 35, as shown in FIG. 36 with the resin layer 68, the low-melting-point metal layer 65, and the partition portion 38b removed, the conductor wiring 33 is disposed below the same as in the second embodiment. The insulating glass layer 36 and the resistor 37 are laminated in this order from the bottom.

  Therefore, the fuse element body 62 can operate in the same manner as the fuse element 31 of the second embodiment.

  A feature of this embodiment is that a cap 63 shown in FIG. 31 is fixed to the upper surface of the fuse element body 62. By covering the laminated portion with the cap 63, it is possible to provide the fuse element 61 having a package structure in which the upper surface is sealed.

  FIG. 32 is a schematic front view of the fuse element 61, and FIG. 33 is a schematic side view. FIG. 34 is a bottom view of the cap 63.

  As shown in FIG. 34, the cap 63 has a substantially rectangular shape and is provided with a recess 63a in the center. The recess 63a is a portion that covers the main part of the fuse element body 62 described above. That is, the concave portion 63a is a portion for accommodating a portion of the fuse element body 62 where the low melting point metal layer is provided.

  The outer periphery of the recess 63 a is a rectangular frame-shaped side wall 64. The rectangular frame-shaped side wall portion 64 is provided so as to extend downward from the top surface of the cap 63. But the lower end surface of the side wall part 64 has three types of height positions. In FIG. 34, the center portions 64a to 64d of each side of the side wall have the highest height position. This is to provide a space for electrically connecting an electrode or the like for connecting to the outside to the outside. On the other hand, the end surface portions 64e to 64l on both sides of the central portions 64a to 64d are located below the central portions 64a to 64d. Further, the corner portions 64m to 64p among the end surfaces of the side walls have the lowest height position. The cap 63 is joined to the upper surface of the fuse element body 62 using an adhesive (not shown).

  In addition, as said adhesive agent, appropriate adhesive agents, such as an epoxy-type adhesive agent, can be used. The cap 63 itself can be formed of an appropriate material such as a synthetic resin or metal.

  On the other hand, on the upper surface of the cap 63, concave portions 63b and 63c shown in FIG. 31 are provided. The recesses 63b and 63c are provided at a pair of corners in the diagonal direction. Providing the recesses 63b and 63c facilitates resin molding.

  The dimensions of the fuse element 61 are not particularly limited, but may be approximately 2.5 mm long × 3.2 mm wide in plan view. Alternatively, the thickness may be about 1.0 mm. Therefore, it can be seen that a considerably small fuse element 61 can be provided.

  FIG. 37 is a plan view showing a fuse element of a sixth embodiment which is a fuse element with a cap, FIG. 38 is a schematic front view thereof, and FIG. 39 is a schematic side view thereof. Also in the fuse element 71 of the present embodiment, a cap 73 is joined to the upper surface of the fuse element body 72. The fuse element body 72 has the same laminated structure as that of the second embodiment on the substrate 72A. That is, as shown in FIG. 41, the resin layer 74 and the low melting point metal layers 75 and 76 are disposed in the opening surrounded by the overcoat layer 77. Below that, a conductor wiring, an insulating glass layer, and a resistor are laminated in this order from the bottom.

  Also in this embodiment, a cap 73 similar to the cap 63 is fixed on the fuse element body 72. FIG. 40 is a bottom view of the cap 73. The cap 73 is configured in substantially the same manner as the cap 63. Accordingly, corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.

  However, in the present embodiment, the size of the cap 73 is different from that of the cap 63. That is, the fuse element 71 of the present embodiment has a substantially rectangular planar shape of 3.0 mm length × 4.0 mm width. The thickness is about 1.0 mm. Also in this embodiment, it can be seen that, similarly to the fifth embodiment, it is possible to provide a fuse element that is small and particularly thin.

  The thickness of the caps 63 and 73 is not particularly limited, but is preferably 0.6 mm or less. Thereby, it is possible to reduce the height.

  FIG. 42 is a front sectional view of a fuse element according to a seventh embodiment of the present invention. The structure of the fuse element 81 will be clarified by describing a method for manufacturing the fuse element with reference to FIGS. 43 to 47. As in the sixth embodiment, the fuse element 41 has a substantially rectangular planar shape of 3.0 mm in length and 4.0 mm in width. The vertical and horizontal dimensions are not particularly limited.

  First, as shown in FIG. 43, the conductor wiring 33A is formed on the substrate. The conductor wiring 33A has the same shape as the conductor wiring 33 shown in FIG. That is, the protruding portion 35 having the connecting portion 35a is formed integrally with the conductor wiring 33A. Further, an auxiliary metal film 33a is provided integrally with the conductor wiring 33A so as to protrude from the side edge opposite to the protruding portion 35 to the side.

  The conductor wiring 33A, the protrusion 35, and the auxiliary metal film 33a can be formed of an appropriate metal material such as Ag.

  Next, as shown in FIG. 44, the insulating glass layer 36 is formed so as to cover the protruding portion 35 and the auxiliary metal film 33a so as to expose a part of the connecting portion 35a and across the conductor wiring 33. To do.

  Thereafter, as shown in FIG. 45, the connection electrodes 43a and 43b are printed. The connection electrodes 43a and 43b are electrodes that are electrically connected to a resistor described later. The connection electrodes 43a and 43b can be formed of the same material as that of the conductor wiring 33A described above.

  Next, as shown in FIG. 46, the resistor 37 is printed on the insulating glass layer 36. The resistor 37 is formed so as to be electrically connected to the connection electrode 43a and the connection electrode 43b described above.

  Thereafter, an overcoat layer 38 is formed as shown in FIG.

  Next, as shown in FIG. 42, a resin layer 45 and a low melting point metal layer 46 are formed in the same manner as in the first embodiment.

  Through the above steps, the fuse element 81 of the seventh embodiment can be obtained. As shown in FIG. 42, in the fuse element 81, the conductor wiring 33A and connection electrodes 43a and 43b exist below the resistor 37 in the direction in which the resistor 37 extends. Accordingly, the metal diffuses over almost the entire region of the resistor 37. For example, when the conductor wiring 33 </ b> A and the connection electrodes 43 a and 43 b are made of Ag, Ag diffuses uniformly over the entire length in the length direction of the resistor 37. Therefore, in the resistor 37, a problem that heat generation is concentrated particularly in a portion having a high resistance hardly occurs. Therefore, the power durability characteristics of the resistor 37 are unlikely to deteriorate.

  FIG. 48 is a schematic plan view for explaining the method for manufacturing the fuse element according to the eighth embodiment of the present invention. The eighth embodiment corresponds to a modification of the seventh embodiment. That is, as shown in FIG. 43, after the conductor wiring 33A, the protrusion 35, and the auxiliary metal film 33a are formed on the substrate 42, the second conductor wiring is formed at the center of the conductor wiring 33A as shown in FIG. 33B is laminated. The second conductor wiring 33B is provided on a conductor portion that functions as a fuse of the conductor wiring 33A.

  The second conductor wiring 33B may be formed of the same metal as the conductor wiring 33A or may be formed of another metal. Preferably, the second conductor wiring 33B is made of the same material as the conductor wiring 33A.

  By laminating the second conductor wiring 33B, the rated current as the fuse element can be increased.

  49 to 53 are plan views for explaining the method of manufacturing the fuse element according to the ninth embodiment, and correspond to FIGS. 43 to 47 shown in the seventh embodiment. The ninth embodiment is a fuse element having a size of about 2.5 mm long × 3.2 mm wide. That is, in the ninth embodiment, a fuse element having the same size as the fuse element 61 described above is formed. Accordingly, the conductor wiring 33C is formed on the substrate 62A as in the case of the fuse element 61. However, also in this embodiment, as in the case of the fuse element 81 of the seventh embodiment, the protruding portion 35 and the auxiliary metal film 33a are formed integrally with the conductor wiring 33C. The tip of the protruding portion 35 is a connecting portion 35a.

  Next, as shown in FIG. 50, the insulating glass layer 36 is formed on the substrate 62A. Next, as shown in FIG. 51, a connection electrode 45a is formed so as to cover one end of the insulating glass layer. The connection electrode 45b is also formed at the other end.

  Thereafter, as shown in FIG. 52, a resistor 37 is printed on the insulating glass layer so as to be connected between the connection electrodes 45a and 45b. Thereafter, an overcoat layer 38 is formed as shown in FIG. Thereafter, similarly to the case of the seventh embodiment, a resin layer and a low melting point metal layer are formed. In this way, the fuse element of the ninth embodiment is obtained.

  The fuse element obtained in the ninth embodiment is formed in substantially the same process as the fuse element 81 except that the substrate 62A having the above dimensions and shape is used. Also in the ninth embodiment, as in the case of the fuse element 81, the metal diffusion degree is uniform over the entire length of the resistor 37. Therefore, heat generation is less likely to occur and the power resistance of the resistor is unlikely to deteriorate.

  FIG. 54 is a plan view for explaining a manufacturing process of the tenth embodiment. The tenth embodiment corresponds to a modification of the ninth embodiment. That is, as shown in FIG. 54, the second conductor wiring 33D is formed on the conductor wiring 33C. The tenth embodiment is the same as the ninth embodiment in other respects. In the tenth embodiment, since the second conductor wiring 33D is provided as in the eighth embodiment, the rated current as the fuse element can be increased.

DESCRIPTION OF SYMBOLS 1 ... Fuse element 2 ... Board | substrate 2a ... Upper surface 2b ... Lower surface 2c, 2d ... 1st, 2nd end surface 2e, 2f ... 1st, 2nd side surface 3-6 ... Electrode land 7a, 7b, 8a, 8b ... Through Hall electrode 11 ... resistor 12 ... insulating glass layer 13 ... conductor wiring 13a ... main body parts 13b, 13c ... wide parts 13d, 13e ... auxiliary metal film 13f ... connecting part 13g ... notches 13h-13m ... auxiliary metal film 14 ... metal Film 15 ... Overcoat layer 15a ... Rectangular frame-like portion 15b ... Connection portion 19 ... Resin layer 20, 20A, 20B, 21, 21A, 21B ... Low melting point metal layer 20a, 21a ... Projection 20b, 21b ... Extension 22 ... Lead portion 23 ... conductor wiring 24 ... low melting point metal layer 31 ... fuse element 32 ... substrate 32a ... upper face 32b ... lower face 32c, 32d ... first and second end faces 32e, 32f ... side faces 33, 33A, 33 33C, 33D ... Conductor wiring 33a ... Auxiliary metal film 34 ... Electrode land 35 ... Projection 35a ... Connection part 36 ... Insulating glass layer 37 ... Resistor 38 ... Overcoat layer 38a ... Rectangular frame part 38b ... Partition part 38c, 38d ... openings 39a-39c ... resin layers 40, 41 ... low melting point metal layer 42 ... substrates 43a, 43b ... connection electrodes 45 ... resin layer 46 ... low melting point metal layers 51, 52, 61, 71, 81, 91 ... Fuse elements 62, 72 ... fuse element bodies 62A, 72A ... substrates 63, 73 ... caps 63a-63c ... concave portions 64 ... sidewall portions 64a-64d ... central portions 64e-64l ... both side end face portions 64m-64p ... corner portions 65, 66 75, 76 ... low melting point metal layers 67, 77 ... overcoat layers 68, 74 ... resin layers

Claims (12)

A substrate,
Conductor wiring provided on the substrate;
A low melting point metal layer that is provided so as to directly or indirectly cover a part of the conductor wiring, has a lower melting point than the conductor wiring, and forms a melted portion by melting the conductor wiring as a melt; With
The low melting point metal layer, Ri Do from Bi-based alloy containing pure Bi or Bi 80 wt% or more,
Further comprising a resin layer provided in contact with the low melting point metal layer, the resin layer is ing from the crystalline thermoplastic resin, the fuse element. The fuse element according to claim 1, wherein the resin layer is provided so as to cover at least a part of the conductor wiring. The fuse element according to claim 2, wherein the resin layer is provided so as to cover at least a part of the low melting point metal layer. The conductor wires, made of an alloy mainly containing Ag or Ag, a fuse element according to any one of claims 1-3. An auxiliary metal film provided on the substrate so as to be located at a part of a lower surface of the low melting point metal layer in a region where the low melting point metal layer is provided;
When the direction in which the conductor wiring extends is defined as the first direction and the direction orthogonal to the first direction is defined as the width direction, the auxiliary metal film extends outward from the edge in the width direction of the conductor wiring in the width direction. and has a dimension of the first direction of the auxiliary metal film, the ratio of the width dimension is not less than 0.3, the fuse element according to any one of claims 1-4. Provided directly or indirectly on the substrate or in the substrate, further comprising a heating element that generates heat when a current flows;
Said heating element, said being connected to a part of the conductor wiring, the heating element is the heating elements are provided so as to blow the conductor wires by heat in the case of heating, according to claim 1 to 5 The fuse element according to any one of claims. The fuse element according to claim 6 , wherein the heating element is a resistor. The fuse element according to claim 7 , wherein the resistor is formed of a resistance film provided on the substrate, and further includes an insulating glass layer provided between the resistance film and the conductor wiring. The fuse element according to claim 7 , wherein the conductor wiring, the insulating glass layer, and the resistor are laminated in this order from the bottom. The fuse element according to any one of claims 6 to 9 , wherein the heat generating element does not overlap the low melting point metal layer. It is a manufacturing method of the fuse element given in any 1 paragraph of Claims 1-10 ,
Providing conductor wiring on the substrate;
A low melting point metal having a melting point lower than that of the conductor wiring and forming a melted portion by melting the conductor wiring so as to directly or indirectly cover a part of the conductor wiring on the substrate. Forming a layer of pure Bi or a Bi-based alloy containing 80% by weight or more of Bi. The method for manufacturing a fuse element according to claim 11 , further comprising a step of forming a resin layer on the substrate so as to be in contact with the low melting point metal layer.

Images