JP2017050478A - Resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistor that improves reliability in external connection and mounting efficiency, is low cost, has high heat dissipation efficiency, and is capable of being downsized.SOLUTION: A resistor includes: a resistance substrate 11 configured by forming a resistive element 12 and a pair of electrodes 13 on a surface of an insulating substrate; and a metal plate on a rear surface of the resistance substrate. The metal plate includes connection parts 20a, each electrically connected to an external part. The metal plate is composed of a first metal plate 15 and a second metal plate 16, which are mutually separated. The first metal plate 15 fixes the resistance substrate 11 and is connected to one of the electrodes 13 by a metal wire 14. The second metal plate 16 is connected to the other one of the electrodes 13 of the resistance substrate 11 by the metal wire 14.SELECTED DRAWING: Figure 3

Description

  The present invention relates to resistors, and more particularly to resistors for high power applications.

  As an example of such a resistor, there is known a high power type resistor in which a resistor substrate 30 in which a thick film resistor 35 is printed on a flat ceramic substrate 31 is mounted on a radiator plate 10 (Patent Document 1). FIG. 2). Two silver electrode patterns 33 are printed on the resistor substrate 30, and two lead wires 50 are soldered on each silver electrode pattern 33.

  As another example, the resistor thin film 2 and the electrode plate 4 for connecting the lead wires 3 are formed on the surface of the substrate 1, and the metal thin film 5 is formed on the back surface of the substrate 1 to form the resistor 6. A high power type resistor in which a resistor 6 is bonded to a metal heat sink 8 via a metal thin film 5 and solder 7 is known (see FIG. 1 of Patent Document 2).

Utility Model Registration No. 2598026 Japanese Patent Laid-Open No. 3-141607

  In general, a high-power resistor equipped with a heat sink (metal plate) uses a lead wire or a harness wire for connection to the outside. And it connects to the electrode which connected the lead wire and the harness wire with the resistor using fixing materials, such as solder. For this reason, it is necessary to connect the lead wire or the harness wire to the outside at the time of mounting and to fix the heat radiating plate (metal plate) by screws or the like, and improvement in mounting efficiency has been desired.

  The present invention has been made based on the above circumstances, and provides a resistor that improves the reliability and mounting efficiency of external connection, has high heat dissipation efficiency at low cost, and can be miniaturized. Objective.

  The resistor according to the present invention is a resistor substrate formed by forming a resistor and a pair of electrodes on the surface of an insulating substrate, and a metal plate on the back surface of the resistor substrate. And a first metal plate and a second metal plate that are spaced apart from each other, the first metal plate fixing the resistance substrate, and one electrode and a metal wire. The second metal plate is connected to the other electrode of the resistance substrate by a metal wire.

  According to the present invention, the metal plate is made of the same material as the bus bar of the external circuit and is provided with connection portions that are electrically connected to the outside at both ends. Can be connected to an external circuit. Then, heat can be released to the bus bar or the like of the external circuit. Therefore, it is possible to provide a resistor that improves the reliability and mounting efficiency of connection with an external circuit, has high heat dissipation efficiency, and can be downsized.

It is sectional drawing of the resistor of one Example of this invention. It is a top view of the resistor. However, the mold resin body is indicated by a broken line. It is a perspective view of the said resistor. However, the display of the mold resin body is omitted. It is sectional drawing of the modification of the said resistor, and shows the example which formed the unevenness | corrugation corresponding to the boundary part of a 1st metal plate and a 2nd metal plate mutually. It is a top view of the modification of the said resistor, and shows the example which formed the unevenness | corrugation corresponding to the boundary part of a 1st metal plate and a 2nd metal plate mutually. It is sectional drawing and a top view which show the modification of the said resistor, and shows the example which formed the slit (groove | channel) in the metal plate. It is sectional drawing which shows the modification of the said slit (groove). It is a top view which shows the modification of the said slit (groove). It is a flowchart which shows the example of a manufacturing method of the resistor of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

  1-3 shows the structure of the resistor 10 of one embodiment of the present invention. The resistor 10 includes a resistor substrate 11 having a resistor 12 and a pair of electrodes 13 formed on the surface of an insulating substrate, and a metal plate for heat dissipation on the back side of the resistor substrate 11. The metal plate is provided with connection portions (for example, screw holes 20a) that are electrically connected to the outside at both ends, and are electrically connected to the bus bar 19 of the external circuit, for example, by fastening bolts 20 or the like, and insulated from each other. The first metal plate 15 and the second metal plate 16. The connecting portion may be connected to the outside by welding or the like, or may be connected to the outside by fixing the metal plate and the bus bar with a crimp terminal.

  The insulating substrate has a rectangular parallelepiped shape made of alumina or the like. A resistor 12 and a silver-based or silver-palladium-based electrode 13 are formed on the upper surface to form a resistance substrate 11. Either the electrode 13 or the resistor 12 may be formed first. The resistor 12 is a ruthenium oxide thick film resistor formed by, for example, screen printing. The resistor 12 can be formed in a rectangular parallelepiped pattern, a meandering pattern, or the like.

  The material of the metal plates 15 and 16 is preferably aluminum, copper, or an alloy thereof. The metal plate 15 and the metal plate 16 are arranged at a predetermined interval that is a sufficient distance for insulation. As will be described later, the boundary portion A is filled with mold resin, and the metal plates 15 and 16 are integrally formed. Since the metal plate 15 and the metal plate 16 are adjacent to each other as shown in the figure, the resistor can be reduced in height.

  The first metal plate 15 fixes the resistance substrate 11 and is connected by wire bonding of one electrode 13 to the metal wire 14, and the second metal plate 16 is connected to the other electrode 13 of the resistance substrate 11 and the metal wire 14. Are connected by wire bonding. The first metal plate 15 that fixes the resistance substrate 11 is larger than the second metal plate 16. This has the effect that the resistor 10 can be miniaturized as a whole by securing the heat dissipation effect by the first metal plate 15 and reducing the size of the second metal plate 16. By making the connection between the electrode 13 and the metal plates 15 and 16 a wire bonding connection, the connection can be made firmly in a simple process.

  Since both electrodes 13 of the resistor substrate 11 are connected to the metal plates 15 and 16 by the metal wires 14, respectively, a harness and lead wires for external connection are not required as in the prior art. Therefore, downsizing, low profile, and low cost can be realized while ensuring heat dissipation. An adhesive layer 17 made of silver paste, conductive adhesive, or the like is formed on the back surface of the resistive substrate 11 by coating or the like, and the resistive substrate 11 is fixed to the first metal plate 15 via the adhesive layer 17.

  The metal wire 14 is a wire or a lead wire, and in the structure shown in FIG. 1C, there are connection places at three locations, the electrode center and both ends of the electrode. However, the connection can be made in an arbitrary arrangement and does not have to be three places. In the case of a wire, it is connected by ultrasonic welding or the like. From the viewpoint of strength, a wire is preferable.

  Part of the resistance substrate 11 and the metal plates 15 and 16 covers the resistance substrate 11 and the metal wires 14, and a mold resin body 18 made of epoxy resin or the like is provided so that the lower surfaces of the metal plates 15 and 16 are exposed. Alternatively, the resistor substrate 11 and the metal wire 14 may be protected by covering with a case made of resin or ceramic and filling the case with a cement material or a resin potting material.

  Further, since the first and second metal plates 15 and 16 need to be insulated, the resin is injected between the first and second metal plates 15 and 16 so that the resin enters between the first and second metal plates 15 and 16. It is desirable to do. Note that the mold resin does not cover the lower surface of the metal plate for heat dissipation in the figure, but may cover the lower surface except for a connection point with an external circuit such as the bus bar 19.

  Since the resistance substrate 11 is fixed on the first metal plate 15, the metal plate 15 larger than the metal plate 16 is positioned under the resistor 12 that generates the most heat. Therefore, the heat generation of the resistor 12 can be efficiently cooled, and can be applied to high power applications. Further, since the resistance substrate 11 which is an insulating substrate is supported by the metal plate 15, it is possible to prevent the resistance substrate 11 from being cracked due to stress generated when the resistor 10 is mounted on a circuit board, a bus bar or the like. .

  Each of the metal plates 15 and 16 is connected to the electrode 13 of the resistance substrate 11 by a metal wire (wire or lead wire) 14, and the metal plate is electrically connected to an external circuit. Flowing. Screw holes 20a are formed at both ends of the substantially rectangular metal plates 15 and 16 in the longitudinal direction, and the resistor 10 is mounted (connected) by being fixed to a circuit board, a bus bar or the like with screws (bolts) 20. can do.

  That is, since the metal plates 15 and 16 are made of the same metal material as the bus bar 19 of the external circuit, the metal plates 15 and 16 can be easily and securely fastened by screwing (bolting) screws (bolts) 20 to the bus bar 19 of the external circuit. It can be firmly mounted (connected). As a result, the connection is simple, the mounting can be performed efficiently, and a highly reliable connection can be obtained. Then, heat can be released to the bus bar or the like of the external circuit, and the cooling efficiency is improved.

  As shown in FIG. 4, unevenness (corrugated shape) corresponding to each other may be formed in the boundary portion A between the first and second metal plates 15 and 16. That is, in the boundary portion A, the separation distance between the metal plate 15 and the metal plate 16 is approximately constant in a cross-sectional view, but is bent twice in (a) and four times in (b) and (c). It has an irregular shape that bends.

  In the boundary portion A between the first and second metal plates 15 and 16, as shown in FIGS. 5A and 5B, asperities corresponding to each other may be formed in a top view. . In (a), the concavo-convex shape is bent twice, and in (b), the concavo-convex shape is bent four times.

  Thereby, the surface area which the boundary part A of the metal plates 15 and 16 faces increases, and heat dissipation is improved. In addition, the boundary portion A is filled with a resin for joining the metal plates 15 and 16, and there is an advantage that the area of the joined portion is widened and the strength against vibration and the like is improved. As shown in FIG. 4-5, various structures are possible for the uneven structure.

  6-8, the metal plates 15 and 16 may be provided with slits (grooves) C. When the metal plates 15 and 16 are fastened and fixed to the circuit board or bus bar by screwing or the like, stress is applied to the metal plates 15 and 16 and the resistance board 11 at the time of fastening, and the following problems may occur.

  The metal plates 15 and 16 are distorted and deformed, and are lifted from the circuit board or the like. Due to the deformation of the metal plate 15, the resistance substrate 11 is peeled off from the metal plate 15, and heat dissipation and conduction cannot be ensured. Due to the deformation of the metal plate 15, the resistance substrate 11 is cracked. When the mounting side (circuit board, bus bar, etc.) is distorted, the resistance board 11 is lifted or cracked.

  In order to solve the above problem, slits (grooves) C for relaxing stress are formed in the metal plate. The formation position of the slit (groove) C is preferably outside the mold resin body 18 and inside the screw hole 20a. The slit shape is square (see FIG. 6A), trapezoid (see FIG. 7A), elliptical (see FIG. 7B), or the like when viewed from the side.

  When viewed from above, the slit shape is preferably linear (see FIG. 6 (b)) or oblique (see FIG. 8 (a)), as well as the shapes of FIGS. 8 (b) and 8 (c). The slit C in FIG. 8C may penetrate the heat sink. Also, the above structures can be combined. Note that the slit may be formed on either the front surface or the back surface of the metal plate. Moreover, you may form from both the surface and a back surface.

  Next, a method for manufacturing a resistor according to the present invention will be described with reference to FIG. First, a large-sized large-sized insulating substrate to be used as a resistance substrate is prepared. Then, a dividing groove is formed. Next, the electrode 13 (Ag or Ag / Pd) and the resistor 12 (ruthenium oxide or the like) are patterned by screen printing and formed by firing.

  The resistance value can be adjusted to a desired value by adjusting the width and thickness of the resistor and further forming a trimming groove in a part of the resistor. A glass protective film or a resin protective film may be formed on the resistor separately from the mold that covers the electrode and the resistor. There is no problem even if the order of the electrode forming step and the resistor forming step is reversed, but since a large electrode area is required for wire bonding, it is preferable to form the electrode 13 after forming the resistor 12. The electrode 13 may be plated with Ni, Sn, or Au.

  And the resistance board | substrate 11 is formed by dividing | segmenting a large-sized insulated substrate into a strip shape, and also dividing | segmenting into a piece. The adhesive layer 17 on the back surface of the insulating substrate (resistive substrate) 11 is formed after dividing the individual pieces for easy division, but can also be formed after dividing into strips or in the state of a large substrate.

  Next, the resistance substrate 11 is bonded to the previously prepared metal plate 15 via the adhesive layer 17. Then, the metal wire 14 is connected to the electrode 13 of the resistance substrate 11 and the metal plates 15 and 16 by wire bonding. Furthermore, the resistor 10 of the present invention is completed by molding and forming the molded resin body 18.

  As described above, the resistor 10 can improve the reliability of connection with an external circuit and the mounting efficiency, has high heat dissipation efficiency, and can be downsized.

  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.

The present invention can be suitably used for resistors, particularly resistors for high power applications.

Claims (5)

A resistor substrate formed by forming a resistor and a pair of electrodes on the surface of the insulating substrate, and a resistor including a metal plate on the back surface of the resistor substrate,
The metal plate comprises a first metal plate and a second metal plate that are provided with connection portions that are electrically connected to the outside at both ends, and are separated from each other,
The first metal plate fixes the resistance substrate and is connected to one electrode by a metal wire,
The second metal plate is a resistor connected to the other electrode of the resistance substrate by a metal wire.   The resistor according to claim 1, wherein the first metal plate and the second metal plate are arranged adjacent to each other and are insulated from each other.   The resistor according to claim 1 or 2, wherein the connection between the first metal plate and the second metal plate and the electrode is a wire bonding connection.   The resistor according to any one of claims 1 to 3, wherein the first metal plate and the second metal plate are mounted by screw fastening, and a groove is formed in the metal plate. The resistor according to any one of claims 1 to 4, wherein the first metal plate is larger than the second metal plate.

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