JP2005183413A - Metal resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal resistor in which a low resistance metal resistor is imparted with a fuse function blowing out when an abnormal current flows. <P>SOLUTION: The metal resistor 10 consists of a rectangular resistor body 11 composed of a metal resistor material, and rectangular electrodes 12 and 13 composed of a metal electrode material and bonded to the opposite end parts of the resistor in the longitudinal direction wherein the resistor body 11 between the electrodes 12 and 13 is provided with a blow-out part 17 contiguously to one electrode 12. The blow-out part 17 is preferable formed by grooves 15, 15 or cuts 35, 35 extending in the short side direction of the resistor body 11. Since the resistor body 11 is provided with the blow-out part 37 contiguously to the electrode 12 where heat is generated significantly by thermoelectromotive force, fuse function can be imparted even to a metal resistor which is not damaged easily even when a high current flows. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal resistor, and more particularly to a metal resistor having a fuse function.

For example, a precision electronic device such as a mobile phone or a personal computer has a low resistance value on the order of milliohms (mΩ), and has a metal resistance that can be manufactured to a high-precision resistance value while having surge resistance against static electricity. A vessel may be used. In such a metal resistor, a resistor main body is made of a metal resistor material such as a copper nickel alloy or a nickel chromium alloy to obtain a desired low resistance value (see, for example, Patent Document 1).
JP 2001-118701 A

  Since these metal resistors are excellent in surge resistance, even if an instantaneous abnormal voltage / current or the like enters, they are difficult to melt and have high stability. For this reason, for example, when an abnormality occurs in the connected power supply, for example, when an overcurrent exceeding the rating flows, the metal resistor itself is less likely to be damaged and connected to the resistor. This will cause damage to circuit elements. In such a case, if the metal resistor functions as a fuse and can be blown by an overcurrent, the entire device can be prevented from being damaged by the flowing overcurrent.

  The present invention has been made in view of the above-mentioned circumstances, and by providing a metal resistor having a low resistance value and excellent surge resistance to a fuse function that blows when an abnormal current flows, An object of the present invention is to provide a metal resistor capable of preventing an abnormal current from continuously flowing into a device body and preventing the entire device body from being damaged.

  A metal resistor of the present invention that solves the above problems is a rectangular resistor body made of a metal resistor material, and a rectangular electrode made of a metal electrode material joined to both longitudinal ends of the resistor body. The resistor body between the electrodes is provided with a narrow or thin fusing part at a portion adjacent to one of the electrodes. Here, it is preferable that the fusing part is formed by a groove or a notch extending in a short direction of the resistor body.

  According to the present invention, a thermoelectromotive force is generated at the joint portion between the metal resistance material and the metal electrode material by joining different kinds of metals, and the sign of the voltage generated at this time depends on the type of the metal material to be joined. , That makes use of that. That is, when a current flows through a resistor between electrodes, a junction between the current outflow side or the inflow side electrode and the resistor body generates a large amount of heat depending on the type of the metal resistance material and the metal electrode material. .

  Therefore, the heat generated by the thermoelectromotive force at the junction between the resistor body and the electrode can be biased between the current outflow side and the inflow side. For this reason, when an abnormal current flows by forming a groove or notch in the resistor body near the junction where heat generation due to a large thermoelectromotive force is generated, and providing a fusing part so as to melt at a desired amount of current That part can be easily melted. Therefore, by providing a fusing part at the part of the resistor body that is adjacent to the electrode that generates more heat due to the thermoelectromotive force, it is difficult to damage even when a large current flows, and has excellent surge resistance. In this case, it is possible to provide a fuse function.

  According to the present invention, since the metal resistor can be provided with a fuse function, when an abnormal current flows, the metal resistor functioning for current detection or the like can interrupt the abnormal current. For this reason, the metal resistor can be provided with a circuit protection function, and in some cases, the circuit protection element (fuse) can be omitted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 2 are views showing a first embodiment of a metal resistor and a manufacturing method thereof according to the present invention. 1A and 1B are diagrams showing a configuration of a metal resistor, where FIG. 1A is a perspective view seen from the back side, FIG. 1B is a side view, and FIG. 1C is a perspective view seen from the front side. .

  In FIG. 1, a metal resistor 10 is formed so as to extend in the width direction at both ends in the length L direction of the resistor body 11 having a low resistance value formed in a rectangular shape. And a pair of rectangular electrodes 12 and 13. The resistor body 11 is made of, for example, a metal resistance material made of a CuNi alloy, and the electrodes 12 and 13 are made of, for example, Cu and made of a highly conductive metal electrode material. As will be described later, a molten solder layer is formed on the surfaces of the electrodes 12 and 13 to ensure solderability when the metal resistor 10 is mounted.

  Such a metal resistor 10 has a low resistance value of, for example, 1Ω or less, preferably 1 to 100 mΩ. And it has the external dimension of standard chip components, such as 5.0 mm x 2.5 mm (2H) form, 3.2 mm x 1.6 mm (2B) form, for example. Moreover, such a metal resistor 10 has a resistance temperature coefficient of, for example, 100 ppm or less, is incorporated in a power supply circuit board such as various electronic devices, and is suitably used for applications such as current detection.

  The resistor body 11 is formed to have a predetermined width W and thickness t, and the electrodes 12 and 13 are separated from both ends of the resistor body 11 and are joined to extend in the width W direction. . The resistor 10 has a desired resistance value according to the size (length) of the gap G between the electrodes 12 and 13 of the resistor body 11 and the predetermined width W and thickness t of the resistor body 11. Can be. Although not shown, it is of course possible to form a trimming groove by laser trimming or the like to adjust the resistance value with high accuracy.

  The metal resistor 10 has grooves 15 and 15 having a length l, a width g, and a depth d parallel to the electrode 12 on both sides in the width direction (short direction) of the resistor body 11 adjacent to one electrode 12. Is engraved. As a result, the resistor body 11 has a vertical cross-sectional area serving as a current path between the electrodes 12 and 13 that is narrower than the other portions, and the portions where the grooves 15 and 15 are formed have a small current capacity. It is formed in the melted part 17 which is easy to melt. Here, a bridge (thick part) 16 that connects the electrode 12 side and the 13 side (both edges of the groove 15) is formed at the center of the grooves 15, 15 of the resistor body 11 in the fusing part 17. Therefore, the strength in the plane direction is ensured.

  Here, in the metal resistor 10, since the electrodes 12 and 13 of Cu, which is a highly conductive metal, are joined to both ends of the resistor body 11 made of a metal resistance alloy such as CuNi, the thermoelectromotive force is generated at this joined portion. Occurs. This metal resistor 10 generates heat due to the current flowing through the resistor body 11, but at the junction between the resistor body 11 and the electrodes 12, 13, the electrode 12 is used as a positive electrode (current inflow side). When a current is supplied from the positive side of the DC power source with 13 as a negative electrode (current outflow side), even if the groove 15 is not formed, the electrode 12 side has 1.4-2 of the electrode 13 side due to the direction of the thermoelectromotive force. There is about twice as much fever. The thickness of the bridge 16 may be smaller than the thickness of the resistor body 11.

  For this reason, the metal resistor 10 forms grooves 15 and 15 in a portion adjacent to the electrode 12 of the resistor body 11, and the longitudinal cross-sectional area of the resistor body 11 in that portion is 1/4 to By adjusting to about 1/20, the heat generation due to the thermoelectromotive force depending on the direction of input / output of current and the Joule heat due to the resistor component cause a heat generation bias of 8 to 50 times between the electrode 12 side and the electrode 13 side. Can be made. That is, the metal resistor 10 has a length of the groove 15 so as to generate heat that causes the fusing part 17 on the electrode 12 side to melt when an abnormal current of a predetermined magnitude flows into the electronic device body. By designing the length l, the width g, and the depth d, the abnormal current can be interrupted by fusing the fusing portion 17 of the metal resistor 10 when the abnormal current flows. Thereby, for example, when an abnormal current is generated in the power supply circuit or the like, it is possible to prevent damage to the electronic device body.

  As shown in FIG. 1C, the metal resistor 10 has an insulating resin mark 18 on the surface of the resistor body 11 which is the back surface on the side where the fusing portion 17 is formed (electrode 12 side). The mark 18 indicates the direction in which current flows as described above. The mark 18 is for indicating the directionality of the chip component at the time of mounting, and needless to say, the shape, material, etc. of the mark may be determined as appropriate.

  Next, a method for manufacturing the metal resistor 10 will be described. First, a strip-shaped material 20 is prepared in which strip-shaped metal materials 23 (12) and 23 (13) to be metal electrodes 12 and 13 are arranged at both ends in the width direction of a strip-shaped resistor material 21 (11) to be the resistor 11. . And as shown to Fig.2 (a), the bridge | bridging (thick part) 16 when it is set as the resistor main body 11 by cutting with a mill, for example in the part adjacent to one metal material 23 (12). In order to remain, an intermittently continuous parallel groove 25 having a length l, a width g, and a depth d is formed twice.

  After this, the mark 18 is formed by printing and heating and curing an insulating resin such as an epoxy resin on the back side of the resistor material 21 of the partial metal material 23 that becomes the electrode 12 while feeding the belt-shaped material 20. Form. At this time, it is preferable to form a display by printing together necessary items such as a product code and a resistance value.

  Then, as shown in FIG. 2 (b), the band-shaped material 20 is fed by the width W of the product size, and a dicing saw or the like is used as shown by a one-dot chain line in the figure in a direction perpendicular to (intersect) the center of the groove 25 Disconnect. Thereby, the rectangular metal resistor 10 provided with the fusing part 17 formed by the grooves 15 and 15 and the bridge (thick part) 16 between them adjacent to the electrode 12 of the resistor body 11 is cut out. The metal resistor 10 cut out from the band-shaped material 20 has an external dimension of a standard chip component of a predetermined size, for example, 5.0 mm × 2.5 mm (2H) type, 3.2 mm × 1.6 mm (2B) type, or the like. Separated into rectangular chip products. In addition, the cutting | disconnection from the strip | belt-shaped material 20 for every metal resistor 10 is performed in the direction which goes to the resistor material 21 from the metal material 22 side, The burr | flash by cutting | disconnection is the resistor main body 11 side from the electrode 12 and 13 side. It is preferable to form so that it may face.

  Thereafter, the entire surface of the resistor body 11 on the back side of the electrodes 12 and 13 is polished while detecting the resistance value between the electrodes 12 and 13 (the resistor body 11) of the metal resistor 10. Thus, the resistance value adjustment with high accuracy may be performed. Further, the resistance value adjustment may be performed by fine adjustment of the width W of the resistor body 11 or may be performed by so-called laser trimming. Then, the metal resistor 10 is completed through processes such as measurement and inspection.

  In the metal resistor 10 of the present embodiment, it is preferable that the metal resistor 10 is mounted on the power supply circuit board so that the mark 18 is a mark and the electrode 12 is connected to a DC power supply with the positive side (the electrode 13 is the negative side). . As a result, when an abnormal current flows in, uneven heat generation occurs at the joint portion with the electrodes 12 and 13, so that the fusing portion 17 on the electrode 12 side of the resistor body 11 can be blown, and the fuse Can function as. Accordingly, since the metal resistor can be provided with a fuse function, when an abnormal current of a predetermined magnitude flows, the metal resistor functioning for current detection or the like can block the abnormal current. For this reason, it is possible to provide a circuit protection function to a metal resistor having excellent surge resistance, and when a circuit protection element (fuse) is attached to a power supply circuit in the past, the circuit protection element (fuse) The arrangement can be omitted.

  Next, FIGS. 3 and 4 are views showing a metal resistor and a manufacturing method thereof according to the second embodiment of the present invention. In addition, in this embodiment, since it is comprised substantially the same as the said 1st Embodiment, the same code | symbol is attached | subjected to the same element or member, the overlapping description is abbreviate | omitted, and only a characteristic part is demonstrated.

  3A and 3B are diagrams showing a configuration of a metal resistor according to a second embodiment of the present invention, wherein FIG. 3A is a perspective view seen from the back side, FIG. 3B is a side view, and FIG. 3C is a front side. It is the perspective view seen from. In FIG. 3, a metal resistor 30 includes a resistor body 11 and a pair of electrodes 12 and 13. The metal resistor 30 is cut in place of the grooves 15 and 15 in the first embodiment. Notches 35 and 35 are formed.

  The notches 35 and 35 are formed adjacent to the electrode 12 of the resistor body 11 on both sides in the width direction (short direction) so as to penetrate the front and back of the resistor body 11 with a length l and a width g. Has been. A bridge (thick part) 36 that connects the electrode 12 side and the 13 side (both edges of the notch 35) is formed between the notches 35, 35 (by being left), so that the electrode 12 , 13 is narrowed to be smaller than that of the other portion, and the current capacity of the resistor body 11 is reduced to facilitate fusing. The bridge 36 may be thinner than the resistor body 11.

  That is, in this embodiment, the notches 35 and 35 and the bridge (thick part) 36 constitute a fusing part 37, and the metal resistor 30 is an electrode when an abnormal current flows into the device body. The length l and the width g of the notch 35 are designed so that heat is generated to such an extent that the 12-side bridge (thick portion) 36 is melted. That is, by adjusting the longitudinal cross-sectional area of the resistor body 11 to about 1/4 to 1/20 of the other parts, the heat generated by the thermoelectromotive force due to the direction of current input and output and the Joule heat due to the resistor component, A bias of heat generation of 8 to 50 times is generated between the electrode 12 side and the electrode 13 side. For this reason, when the abnormal current flows in, the fusing part 37 of the metal resistor 30 can be blown to cut off the abnormal current. Thereby, for example, when an abnormal current is generated in the power supply circuit or the like, it is possible to prevent damage to the electronic device body.

  The metal resistor 30 includes a protective film 41 made of a glass material on the front surface side of the resistor body 11 and a protective film 42 made of a glass material on the back surface side. These protective films 41 and 42 prevent solder and the like from adhering to the resistor body 11 during mounting and causing an error in the resistance value, and also prevent foreign substances and the like from attaching to the resistor body 11. Furthermore, when the fusing part 37 is blown, a protective film component made of a glass material enters the fusing part 37, and the arc extinguishing characteristics can be improved. A mark 18 indicating the direction of current flow is disposed on the surface of the protective film 41.

  Next, a method for manufacturing the metal resistor 30 will be described with reference to the process chart shown in FIG. First, as in the first embodiment, the strip-shaped metal materials 23 (12) and 23 (13) that form the metal electrodes 12 and 13 at both ends in the width direction of the strip-shaped resistor material 21 (11) that serves as the resistor 11. A band-shaped material 20 in which is arranged is prepared. Then, as shown in FIG. 4A, while feeding the band-shaped material 20, the portion of the resistor material 21 adjacent to the portion 23 that becomes the electrode 12 is doubled in length l and width by, for example, punching or the like. The parallel slits 45 that are intermittently continuous are formed at g.

  Thereafter, as in the first embodiment, as shown in FIG. 4 (b), the band-shaped material 20 is fed by the width W of the product size, and the center of the slit 45 is shown in a direction orthogonal (intersect). Cut with a dicing saw or the like as indicated by the alternate long and short dash line. Thereby, the rectangular metal resistor 30 in which the fusing part 37 provided with the notches 35 and 35 and the bridge 36 is formed in the resistor body 11 between the electrodes 12 and 13 is cut out and separated from the belt-shaped material 20. . Further, a protective film 41 is formed on the front surface side of the resistor body 11, and a protective film 42 is formed between the electrodes 12 and 13 on the back surface side of the resistor body 11 by potting and low-temperature baking. Then, the metal resistor 30 is completed through processes such as marking formation, measurement, and inspection.

  Since the metal resistor of the present invention has a function as a fuse, it is desirable to use a flame retardant material having low thermal conductivity as the material used for the protective film 41 and the protective film 42. For example, silicon, glass, and a resin containing a nonflammable filler. Further, instead of forming the protective film 41 and the protective film 42, a ceramic substrate may be attached to the front and back surfaces of the resistor body 11.

  As described above, also in the present embodiment, the resistor main body 11 is provided with the narrow fusing portion 37 by the notches 35 and 35 adjacent to the electrode 12 where the large heat generation due to the thermoelectromotive force is generated. The same effect as the embodiment can be obtained.

  FIG. 5 is a diagram showing a configuration of a metal resistor according to the third embodiment of the present invention. The metal resistor 50 includes a resistor body 11 and a pair of electrodes 12 and 13, and includes a fusing part 57 formed by a continuous groove 15 in the vicinity of the electrode 12. Accordingly, in this embodiment, unlike the first and second embodiments, a bridge (thick part) is not provided, and a thin part by the groove 15 constitutes a fusing part 57. The effect of the fusing part 57 is the same as that of the metal resistor of the above embodiments.

  In addition, although one Embodiment of this invention was described so far, it cannot be overemphasized that this invention is not limited to the above-mentioned embodiment, and may be implemented with a different form within the range of the technical idea.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the metal resistor which concerns on this invention, (a) is the perspective view seen from the back surface side which shows the main structure, (b) is the side view, (c) FIG. 3 is a perspective view seen from the surface side. It is a figure which shows the manufacturing method, (a) is the figure which shows the process of forming the groove | channel of a fusing part, (b) is the figure which shows the process of cutting a strip-shaped material and cutting out a metal resistor, respectively. It is a figure which shows 2nd Embodiment of the metal resistor which concerns on this invention, (a) is the perspective view seen from the back surface side which shows the main structure, (b) is the side view, (c) FIG. 3 is a perspective view seen from the surface side. It is a figure which shows the manufacturing method, (a) is a figure which shows the process of cutting a strip-shaped material, and forming a slit, (b) is the process of cutting a strip-shaped material and cutting out a metal resistor. It is a figure which shows 3rd Embodiment of the metal resistor which concerns on this invention.

Explanation of symbols

10, 30, 50 Metal resistor 11 Resistor body 12, 13 Electrode 12a, 13a Molten solder layer 14 Recess 15, 25 Groove 16, 36 Bridge (thick part)
17, 37 Fusing part 18 Mark 20 Strip material 21 Resistor material 22 Metal material 22a Molten solder layer 35 Notch 45 Slit

Claims (5)

A metal resistor comprising a rectangular resistor body made of a metal resistor material, and a rectangular electrode made of a metal electrode material bonded to both longitudinal ends of the resistor body,
The resistor body between the electrodes is provided with a narrow or thin fusing portion at a portion adjacent to one of the electrodes.   The metal resistor according to claim 1, wherein the fusing part is formed by a groove extending in a short direction of the resistor body.   The metal resistor according to claim 1, wherein the fusing part is formed by a notch extending in a short direction of the resistor body.   The metal resistor according to claim 2 or 3, wherein a part of the fusing part is made thick.   The metal resistor according to claim 1, wherein the resistor is provided with a mark indicating a current flow direction.

Images