JP2013143417A - Resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistor with high rush resistance capable of fusing a resistive element quickly and safely in abnormal loading without exerting any adverse influence such as heating of a component arranged at a periphery by heat storage effect when an overcurrent equal to or larger than a rated current flows to the resistor.SOLUTION: A resistor includes: a resistance body 13 having a resistance winding 12 or resistance coating 12 on an outer peripheral surface of an insulating base material 11; a lead terminal 14 which is led out of both ends of the resistance body; and a cylindrical insulator 15 which has a through hole, into which the resistance body is inserted, from one end to the other end. The cylindrical insulator has a metal film 16 on at least one of an outer peripheral surface and an inner peripheral surface.

Description

  The present invention relates to a resistor with a lead terminal including a rod-shaped resistor body and a lead terminal drawn from the resistor body, and more particularly to a resistor having high lash resistance such as a winding resistor or a metal oxide film resistor. .

  Conventionally, resistors with lead terminals such as winding resistors and metal oxide film resistors have been widely mounted on various circuit boards. These resistors with lead terminals generally include a resistor made of a metal winding or a metal oxide film on the outer peripheral surface of a cylindrical insulating ceramic substrate, and a required resistance value is formed by the resistor.

  In these resistors with lead terminals, there are known ones in which a resistor is inserted into a through-hole provided in a case and the terminals are bent toward the bottom surface of the case so as to be surface-mounted (for example, see Patent Document 1).

  Such a resistor with a lead terminal is used as a rush current limiting resistor for an AC / DC conversion power supply circuit or the like as an example. That is, it is inserted into a circuit that rectifies AC power and supplies DC power to a load, and is used for applications that limit inrush current that occurs when the switch is turned on. In such a resistor, in order to limit the inrush current generated when the switch is turned on, high resistance to rush that can withstand an instantaneous large current several times the rating is required.

Japanese Patent Laid-Open No. 9-237701

  In such a resistor, when an overcurrent exceeding the continuous rating flows for some reason, the resistor is difficult to melt due to its high rush resistance, and the resistor is heated by a heat generated by the resistor. Become. Then, there is a case where the heat is transferred to the mounting substrate around the resistor and adversely affects such as heating damage to components arranged around the resistor.

  The present invention has been made based on the above-described circumstances. When an overcurrent exceeding the rating flows continuously through a resistor with high lash resistance, a component placed around the resistor due to a heat storage effect inside the resistor is provided. A resistor capable of fusing a resistor quickly and safely at the time of abnormal load due to current overload without causing adverse effects such as heating.

  The resistor according to the present invention includes a resistance body having a resistance winding or a resistance film on an outer peripheral surface of an insulating base, lead terminals drawn from both ends of the resistance body, and a through hole for inserting the resistance body. A resistor having a hole extending from one end to the other end, the cylindrical insulator having a metal film on at least one of the outer peripheral surface and the inner peripheral surface It is characterized by having.

  According to the present invention, the heat generated in the resistor body is directed to the outside of the resistor by radiation, but the metal film formed on the outer peripheral surface or the inner peripheral surface of the cylindrical insulator is the heat released from the resistor. At the same time as blocking radiation, it reflects and stores heat inside the metal film. Therefore, it is possible to prevent adverse effects such as confining the heat generated in the resistor inside the resistor and heating the components arranged around it. Furthermore, due to the heat storage effect during an abnormal load, the resistor internal temperature can reach the fusing temperature of the resistor in a shorter time than the conventional resistor, and the resistor can be blown out. As a result, the overcurrent is cut off, and heat damage to the components arranged in the surrounding area can be prevented, thereby improving safety.

It is a perspective view which shows the resistor of one Example of this invention. 1B is a cross-sectional view showing an example of a winding resistor along the line AA ′ of FIG. 1A. FIG. It is sectional drawing which shows the example of the metal oxide film resistor along the AA 'line of FIG. 1A. FIG. 1B is a cross-sectional view taken along line BB ′ of FIG. 1A. 1B is a perspective view of a cylindrical insulator having a prismatic outer peripheral surface as the resistor shown in FIG. 1A. FIG. It is the perspective view which arrange | positioned the cylindrical insulator 15 so that the center part of the resistance main body 13 may be cyclically covered, and has arrange | positioned the metal film 16 on the outer peripheral surface. 3 is a perspective view in which a metal film 16 is arranged so as to cover a part of the outer peripheral surface of a cylindrical insulator 15. FIG. FIG. 6 is a perspective view in which a slit is formed in the metal film 16 and the metal film 16 is divided into three parts. It is the perspective view which put slit 16s in metal film 16, and divided metal film 16 into two. FIG. 3 is a perspective view in which a metal film 16 is disposed on the inner peripheral surface of a cylindrical insulator 15 and a gap 17 is filled with an insulating material 18 such as glass. It is sectional drawing along the AA 'line of FIG. 5A. FIG. 5B is a cross-sectional view taken along line BB ′ of FIG. 5A. 3 is a cross-sectional view in which outer caps 19 are fitted to both ends of a cylindrical insulator 15. FIG. FIG. 6B is a cross-sectional view showing a modification of FIG. 6A in which an insulating material 20 is inserted to insulate the outer cap 19 and the metal film 16. It is sectional drawing which shows the modification of FIG. 6A which employ | adopted the double cap structure.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1A to 6C. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

  1A-1D show a resistor of one embodiment of the present invention. This resistor has a resistance film (see FIG. 1B) in which a resistance winding (see FIG. 1B) such as NiCr or a metal oxide film such as a tin oxide-based alloy is trimmed on the outer peripheral surface of a cylindrical insulating substrate 11 such as alumina. 1C). A resistor with a lead terminal including a resistor main body 13 including a resistor 12 and a lead terminal 14 drawn from both ends of the resistor main body. Caps 13a are fitted and fixed to both ends of the resistor body 13, and the lead terminals 14 are connected and fixed to the cap 13a. The trimming of the resistor 12 made of a resistance film is performed as necessary.

  And the cylindrical insulator 15 which is a cylindrical case which has the circular through-hole 15a for inserting the column-shaped resistance main body 13 from one end part to the other end part is provided. The cylindrical insulator 15 is made of a material such as ceramics or high heat resistant glass. In the resistor of the present invention, the cylindrical insulator 15 has a metal film 16 on at least one of the outer peripheral surface and the inner peripheral surface. In the illustrated example, the cylindrical insulator 15 is made of ceramics, and a metal film 16 made of Ni is deposited only on the outer peripheral surface thereof. The metal film 16 is not formed on the end face of the cylindrical insulator 15. In the embodiment of FIG. 1, the length of the resistor body 13 and the length of the cylindrical insulator 15 are substantially equal, and the metal film 16 is generated from the resistor 12 by being formed on the entire outer peripheral surface of the cylindrical insulator 15. This makes it easier to trap the heat inside the resistor and has a greater heat storage effect.

  As the metal film 16, a metal material such as Ni, Pd, Pt, Au, or Ag can be used. However, it is preferable to use a metal material having a melting point higher than that of the resistor material, and particularly, Ni, Pd, and Pt. The metal film 16 has a high melting point, and it is preferable that the metal film 16 does not melt even when the resistor 12 is melted at a high temperature as described later. As a method for forming a metal film, an electroless plating method, a sputtering method, a vapor deposition method, a metal foil pasting, or the like can be adopted, but the electroless plating method can be easily and compared with a cylindrical object. It is most preferable because a uniform metal film can be formed at low cost.

  Further, the metal film 16 preferably has a mirror-like surface. Since the metal film 16 has a mirror-like surface, the heat storage effect by heat radiation suppression and reflection is enhanced. In order to obtain a mirror-like surface, it is most preferable to deposit a metal film made of Ni, Pd, and Pt by the electroless plating method so as to cover the irregularities on the surface of the cylindrical insulator 15. When the cylindrical insulator 15 is formed of high heat resistant glass, since the glass has a smooth surface, it can be mirror-like even if it is thinly deposited. When the cylindrical insulator 15 is formed of ceramic, the metal film 16 is deposited relatively thick in order to cover the surface irregularities. More preferably, the surface of the ceramic cylindrical insulator can be polished and then a metal film can be deposited, or the surface of the metal film can be further polished to form a mirror surface.

  As illustrated in FIG. 1D, a gap 17 is provided between the cylindrical insulator 15 and the resistor 12. In this embodiment, air exists in the gap 17 and plays a role as a heat insulating layer because of its low thermal conductivity. Therefore, the heat generated in the resistor 12 due to the overcurrent goes to the outside of the resistor by radiation as indicated by an arrow H in the figure, but the metal film 16 formed on the outer peripheral surface of the cylindrical insulator 15 is heated. Suppresses radiation while reflecting. Then, heat is stored inside the metal film 16 to suppress the influence of heat on the outside. It is preferable that the gaps 17 are substantially equally spaced between the cylindrical insulator 15 and the resistor 12 over the entire circumference of the resistor 12.

  As a result, it is possible to prevent the heat generated in the resistor 12 due to overcurrent from being confined inside the resistor and adversely affecting the components disposed around the mounting substrate. Further, during abnormal load, the resistor 12 can be blown quickly and safely by raising the fusing temperature of the resistor 12 in a short time due to the heat storage effect. As a result, the overcurrent is interrupted, and heating damage to the components arranged around can be prevented.

  That is, when an abnormal load current several times the rated current flows continuously, in the structure without the conventional metal film 16, heat is radiated outside the resistor for a long time due to the high lash resistance of the resistor, A situation occurs in which parts placed around the mounting substrate are damaged by heating. On the other hand, in the structure provided with the metal film 16, the temperature inside the metal film is quickly reached to, for example, about 1400 ° C. which is the melting point temperature of the NiCr resistance winding due to the heat storage effect of the metal film 16. can do. When mounting, the lead terminal is bent and connected to the circuit board so that a space is formed between the cylindrical insulator 15 and the circuit board in the circuit board. It becomes difficult to be transmitted to the board.

  FIG. 2 shows an example in which a cylindrical insulator 15 which is a prismatic case having a through hole 15a for inserting a columnar resistor 13 is used. As shown in FIG. 2, the through-hole 15a is the same as the embodiment of FIG. 1 in that the opening is a circular cavity and the metal film 16 is disposed on the entire outer peripheral surface of the cylindrical insulator 15. It is. Further, the resistor main body 13 is the same as the embodiment of FIG. 1 in that the resistor main body 13 is a resistor with a lead terminal provided with a resistor 12 made of a resistance winding or a resistance film on the outer peripheral surface of the insulating substrate 11.

  As shown in FIG. 1, when the cylindrical insulator 15 having a cylindrical case is used, the metal film 16 formed on the outer peripheral surface of the cylindrical insulator 15 is also cylindrical. Can be converged. On the other hand, if a polygonal columnar case is used for the cylindrical insulator 15, the surface mounting is facilitated by having the corners as shown in FIG. 2, but the heat is less likely to converge on the resistance body 13. Sometimes.

  FIG. 3 shows a resistor according to a modified embodiment of the present invention. In the resistor according to the present invention, the metal film covers at least the central portion of the resistor main body surface in an annular shape. As shown in FIG. 3, in order to make the length of the cylindrical insulator 15 shorter than the length of the resistor main body 13 and cover the central portion where the heat generation temperature is highest in the resistor 12 and is easily melted, the resistor main body 13 is covered. In this example, the metal film 16 is disposed on the entire outer peripheral surface of the cylindrical insulator 15 so as to cover at least the central part of the cylindrical insulator 15 in an annular shape.

  4A, the length of the resistance body 13 and the length of the cylindrical insulator 15 are made substantially equal, and the cylindrical insulator is formed so that the metal film 16 covers at least the center of the resistance body 13 in an annular shape. You may make it arrange | position to a part of 15 outer peripheral surface. Further, as shown in FIG. 4B, the length of the resistor main body 13 and the length of the cylindrical insulator 15 are made substantially equal, the metal film 16 is arranged on the entire outer peripheral surface of the cylindrical insulator 15, and a slit 16s is inserted. The metal film 16 may be divided into three parts 16a, 16b, and 16c. Further, as shown in FIG. 4C, the length of the resistor main body 13 and the length of the cylindrical insulator 15 are made substantially equal, the metal film 16 is arranged on the entire outer peripheral surface of the cylindrical insulator 15, and a slit 16s is inserted. The metal film 16 may be divided into two parts 16d and 16e. The slit 16s is provided in the metal film 16, so that when the outer cap 19 is fitted to the cylindrical insulator 15, there is an advantage that the insulation between the outer cap 19 and the metal film 16 is not necessary.

  FIG. 5A shows an embodiment in which a metal film 16 is disposed on the inner peripheral surface of the cylindrical insulator 15, and the gap 17 in FIG. 1D is filled with an insulating material 18 such as glass. As apparent from FIG. 5B, since the resistor 12 and the metal film 16 are completely insulated and separated by the insulating material 18, the metal film 16 may be disposed on the inner peripheral surface of the cylindrical insulator 15. There are no problems such as deterioration of insulation. In this embodiment, the length of the metal film 16 in the axial direction is made shorter than the length of the cylindrical insulator 15 so as not to cover the cap portion 13a.

  As shown in FIG. 5C, the heat generated in the resistor 12 is directed to the outside of the resistor by radiation as indicated by an arrow H in the figure, but the metal film 16 formed on the inner peripheral surface of the cylindrical insulator 15 In order to reflect heat and prevent radiation of heat, the heat is converged on the resistance body 13 and stored. Accordingly, similarly to the case shown in FIG. 1D, it is possible to prevent an adverse effect such as confining heat generated in the resistor 12 due to overcurrent in the resistor and heating components arranged around the mounting substrate. The metal film 16 may be formed on each of the inner peripheral surface and the outer peripheral surface of the cylindrical insulator 15.

  6A-6C show an example of the sealing structure of this resistor. FIG. 6A shows an example in which outer caps 19 are fitted to both ends of the cylindrical insulator 15. The inner cap 13 a fitted to both ends of the resistor main body 13 is joined to the outer cap 19 for electrical conduction, and the resistor main body 13 is positioned with respect to the cylindrical insulator 15. FIG. 6B is a view in which the axial length of the metal film 16 is extended to the inside of the outer cap 19 with respect to the embodiment of FIG. 6A. An insulating material 20 made of resin is sandwiched between the outer cap 19 and the metal film 16 for insulation. In addition, if the outer cap 19 is formed of an insulating material, it is not necessary to insert the insulating material 20.

  FIG. 6C shows a double cap structure. This is a double cap 21 in which the end of the cylindrical insulator 15 and the inner cap 13a are fitted and fixed. The double cap 21 is formed of a portion 21 a for fitting and fixing the cap 13 a of the resistor main body 13 and a portion 21 b for fitting and fixing the end portion of the cylindrical insulator 15. This double cap structure can also be applied to a structure in which the metal film 16 is provided on the inner peripheral surface of the cylindrical insulator 15. Although not shown in each embodiment, the outer peripheral surface of the resistor may be covered with an insulating resin protective film or housed in an external case.

  Next, the manufacturing process of the resistor of this invention is demonstrated. First, the cylindrical insulator 15 is formed. The cylindrical insulator 15 is formed by forming a metal film on the outer peripheral surface of a long cylindrical insulator by electroless plating, sputtering, vapor deposition, metal anchoring, or the like. In particular, in order to form a metal film having a uniformly smooth surface, it is preferable to form it by an electroless plating method. In addition, when forming a metal film only on the outer peripheral surface of a cylindrical insulator, the metal film is prevented from being formed on the inner peripheral surface and the end surface by closing both end surfaces of the cylindrical insulator. When a metal film is formed on the inner peripheral surface of the cylindrical insulator, it is necessary to mask the outer peripheral surface and both end surfaces. And it cut | disconnects to a predetermined dimension and forms the cylindrical insulator 15 as a piece. The cylindrical insulator 15 is formed by cutting a long cylindrical insulator into a predetermined size in advance and masking the end surface and the inner peripheral surface to form the metal film 16 on the outer peripheral surface, or masking the end surface and the outer peripheral surface. Then, the metal film 16 may be formed on the inner peripheral surface.

  And the resistance main body 13 which formed the resistor 12 which consists of resistance winding or a resistance film in the outer peripheral surface of the insulating base material 11 is inserted in the through-hole 15a of the cylindrical insulator 15, and a resistance main body 13 and cylindrical insulation are inserted. The outer cap 19 is fitted and fixed to both ends of the body 15. Note that an insulating material is filled between the resistor main body 13 and the cylindrical insulator 15 as necessary. This completes the resistor of the present invention.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a resistor with a lead terminal provided with a resistance winding or a resistance film on the outer peripheral surface of an insulating substrate, particularly the above-described resistor having high lash resistance.

Claims (5)

A resistance body having a resistance winding or a resistance film on the outer peripheral surface of the insulating base;
A lead terminal drawn from both ends of the resistor body;
A cylindrical insulator having a through-hole for inserting the resistor main body from one end to the other end, and a resistor,
The said cylindrical insulator has a metal film in at least one surface of an outer peripheral surface or an internal peripheral surface, The resistor characterized by the above-mentioned.   The resistor according to claim 1, wherein a gap is provided between the cylindrical insulator and the resistor.   2. The resistor according to claim 1, wherein the metal film covers at least a central portion of the surface of the cylindrical insulator in an annular shape so as to be positioned at a central portion of the resistor main body.   The resistor according to claim 1, wherein the metal film is a film formed by electroless plating.   The resistor according to claim 1, wherein the metal film has a mirror-like surface.

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