JP2018133440A - Chip resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip resistor capable of improving the resistance value accuracy while obtaining a lower resistance value.SOLUTION: Disclosed chip resistor includes: a pair of electrode terminals 11a, 11b; a first resistance body 12 and a second resistance body 13 bridging the pair of electrode terminals 11a, 11b therebetween; and an insulator layer 14 covering the first resistance body 12 and the second resistance body 13. The first resistance body 12 is connected to the upper face of the pair of electrode terminal 11a, 11b, and the second resistance body 13 is connected to the bottom face of the pair of electrode terminals 11a, 11b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chip resistor using a metal plate as a resistor used for detecting a current value of various electronic devices.

  As shown in FIG. 5, a conventional chip resistor of this type includes a resistor 1 made of a plate-like metal, and a pair of electrodes 2a and 2b formed at both ends of the lower surface of the resistor 1. The protective film 3 formed between the pair of electrodes 2a and 2b and on the upper surface of the resistor 1 was provided. Further, the resistance value is adjusted by forming a slit (not shown) in the resistor 1.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2006-270078 A

  In the conventional chip resistor, it is necessary to increase the film thickness of the resistor 1 in order to obtain a lower resistance value. However, if the film thickness is increased, it becomes difficult to form a slit. There is a problem that there is a possibility that it cannot be improved.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a chip resistor that can improve resistance value accuracy while obtaining a lower resistance value.

  In order to achieve the above object, according to the present invention, the first resistor is connected to the upper surfaces of the pair of electrode terminals, and the second resistor is connected to the lower surfaces of the pair of electrode terminals.

  In the chip resistor of the present invention, two resistors are connected in parallel vertically, so that the overall resistance value can be lowered without increasing the thickness of the resistor, and further, the thickness of the resistor is increased. Since it is not necessary, it becomes easy to form a slit, and this produces an excellent effect that the resistance value accuracy can be easily improved.

Sectional drawing of the chip resistor in one embodiment of this invention Cross-sectional view of another example of the same chip resistor Cross-sectional view of another example of the same chip resistor Cross-sectional view of another example of the same chip resistor Cross-sectional view of a conventional chip resistor

  Hereinafter, a chip resistor according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a chip resistor according to an embodiment of the present invention.

  As shown in FIG. 1, the chip resistor according to the embodiment of the present invention includes a pair of electrode terminals 11a and 11b, a first resistor 12 that bridges the pair of electrode terminals 11a and 11b, and a second resistor. And the insulating layer 14 covering the first resistor 12 and the second resistor 13, the first resistor 12 is connected to the upper surfaces of the pair of electrode terminals 11a, 11b, and the second The resistor 13 is connected to the lower surfaces of the pair of electrode terminals 11a and 11b.

  Further, the resistance value of the first resistor 12 between the pair of electrode terminals 11 a and 11 b is set higher than the resistance value of the second resistor 13. Further, a slit 15 is formed in the first resistor 12 to adjust the resistance value.

  In the above configuration, the pair of electrode terminals 11a and 11b is formed of a conductor separate from the first resistor 12 and the second resistor 13, and the first resistor 12 and the second resistor. 13 is made of metal such as copper having better conductivity. Further, the pair of electrode terminals 11a and 11b are connected to the lower surfaces of both ends in the longitudinal direction of the first resistor 12 by a method such as welding, cladding, plating, etc. Similarly, it is connected to the upper surfaces of both ends by a method such as welding or clad plating.

  The first resistor 12 and the second resistor 13 are made of a metal plate or metal foil made of nichrome, copper nickel, manganin or the like. Further, the first resistor 12 and the second resistor 13 are rectangular in top view.

  The first resistor 12 and the second resistor 13 are connected in parallel vertically, and the resistance value of the chip resistor is the resistance value of the first resistor 12 and the resistance value of the second resistor 13. The combined resistance value of The first resistor 12 and the second resistor 13 are not directly connected to each other through a pair of electrode terminals 11a and 11b therebetween.

  The first resistor 12 has a higher resistance value than the second resistor 13 between the pair of electrode terminals 11a and 11b. Therefore, the current is shunted to the first resistor 12 and the second resistor 13, and flows more to the second resistor 13 having a lower resistance value than the first resistor 12.

  Since a large amount of current flows through the second resistor 13 closer to the mounting substrate, the heat generated by the second resistor 13 is easily dissipated to the mounting substrate. The resistance value of the second resistor 13 is preferably set to 1/3 to 1/10 of the resistance value of the first resistor 12. There is little electric current which flows into the 1st resistor 12, and the emitted-heat amount is small.

  Thus, since the second resistor 13 generates higher heat than the first resistor 12, it is preferable to use the second resistor 13 having good heat dissipation efficiency to the mounting board as the mounting surface.

  The first resistor 12 is formed with a slit 15 for adjusting a resistance value therethrough. Thereby, the resistance value of the whole chip resistor can be set to a predetermined value. The resistance value of the second resistor 13 is preferably 1/3 to 1/10 of the resistance value of the first resistor 12. There is little electric current which flows into the 1st resistor 12, and the emitted-heat amount is small.

  Further, the slit 15 is formed on one side surface of the first resistor 12. The slit 15 is formed by a method such as laser, punching or etching.

Note that a slit 15 may also be formed in the second resistor 13. In this case, it is preferable that the slit 15 formed in the first resistor 12 and the slit 15 formed in the second resistor 13 are provided at different positions in a top view. This is to avoid concentrating the heat generation points.

  Here, as described above, a slit may be formed in the second resistor 13, but when the resistance value of the second resistor 13 is higher than that of the eleventh first resistor 12. Is less preferred because the current flowing to the second resistor 13 is reduced and the heat dissipation efficiency to the mounting substrate is reduced.

  In order to make the resistance value of the second resistor 13 lower than that of the first resistor 12, materials having different resistivities are used, or the thickness and width thereof are changed.

  The insulating layer 14 is composed of a resin such as epoxy, polyimide, or a composite material such as glass epoxy resin, and the like. The upper surface of the first resistor 12, the lower surface of the second resistor 13, and the first resistor It is formed so as to cover the space between the lower surface of the body 12 and the upper surface of the second resistor 13 (between the pair of electrode terminals 11a and 11b).

  Note that the side surface of the first resistor 12 and the side surface of the second resistor 13 may be covered. The insulating layer 14 is filled in the slit 15 and is in contact with the inner surface of the slit 15.

  Further, a pair of end face electrodes 16 made of silver or the like are formed on the end faces of the first resistor 12, the second resistor 13, and the insulating layer 14 by sputtering.

  Furthermore, the pair of end face electrodes 16 are provided with a copper, nickel and tin plating layer (hereinafter not shown) by electroplating, whereby the chip resistor is mounted on the mounting substrate.

  Further, as shown in FIG. 2, the pair of end surface electrodes 16 may be formed so as to be directly connected to both ends of the upper surface of the first resistor 12 and the lower surface of the second resistor 13. By increasing the contact area between the pair of end face electrodes 16 and the first resistor 12 and the second resistor 13, heat is easily radiated by the pair of end face electrodes 16.

  Here, the heat generated in the second resistor 13 by energization of the current is radiated to the mounting substrate through the pair of end face electrodes 16 and the plating layer.

  A part of the heat generated by the second resistor 13 is also transmitted to the first resistor 12 and can be radiated to the mounting substrate via the first resistor 12.

  Therefore, it is preferable to use the insulating layer 14 between the lower surface of the first resistor 12 and the upper surface of the second resistor 13 that has good thermal conductivity.

  At this time, the insulating layer 14a formed between the first resistor 12 and the second resistor 13 is a highly thermally conductive insulating layer 14a having higher thermal conductivity than the other insulating layers 14, and the second The heat generated in the resistor 13 is effectively dissipated to the first resistor 12. The high thermal conductive insulating layer 14a is made of a resin and a filler, and an alumina having a good metal thermal conductivity or a metal such as copper or silver can be used as the filler.

When a metal is used as the filler, it is preferable to use a metal whose surface is covered with an oxide film to enhance insulation. This suppresses a change in resistance value due to contact between the metals and contact between the metal and the first and second resistors 12 and 13, and the pair of electrode terminals 11a and 11b.
This is to prevent a short circuit between the first resistor 12 and the second resistor 13.

  If the particle size of the filler is made smaller than the width of the slit 15, the filler enters the inside of the slit 15, so that the heat dissipation can be further improved.

  Here, it is preferable that the content of the filler contained in the high thermal conductive insulating layer 14a is 10 to 70% by volume. If it is less than 10% by volume, the effect of dissipating the heat generated in the first resistor 12 cannot be obtained. When it is more than 70% by volume, the viscosity of the high thermal conductive insulating layer 14a becomes too high, and workability deteriorates.

  In the above-described chip resistor according to the embodiment of the present invention, since the two resistors (the first resistor 12 and the second resistor 13) are connected in parallel vertically, the first resistor 12. The resistance value of the entire resistor can be lowered without increasing the thickness of the second resistor 13. Furthermore, since it is not necessary to increase the thickness of the first resistor 12 and the second resistor 13, the slit 15 can be easily formed, whereby the resistance value accuracy can be easily improved. It is obtained.

  In addition, since more current flows through the second resistor 13 closer to the mounting substrate than the first resistor 12 and heat is generated more, the heat generated by the second resistor 13 is It becomes easy to dissipate heat to the mounting board.

  Further, as shown in FIG. 3, for the pair of end surface electrodes 16, the insulation of the lower surface of the second resistor 13 is obtained from the length of the pair of end surface electrodes 16 a located on the upper surface of the insulating layer 14 on the upper surface of the first resistor 12. By increasing the length of the pair of end surface electrodes 16b located on the lower surface of the layer 14, the heat generated by the second resistor 13 can be easily dissipated by the mounting substrate.

  Furthermore, as shown in FIG. 4, a metal layer 17 may be formed below the second resistor 13. Further, the heat generated by the second resistor 13 by the metal layer 17 can be easily radiated by the mounting substrate.

  The metal layer 17 is formed on the lower surface of the insulating layer 14 on the lower surface of the second resistor 13, and the periphery of the metal layer 17 is covered with another insulating layer 14b. The metal layer 17 is formed in a plate shape with a material such as copper having good thermal conductivity. The metal layer 17 is not connected to the pair of end face electrodes 16.

  The chip resistor according to the present invention has an effect that the resistance value accuracy can be improved while obtaining a lower resistance value, and particularly resists a metal plate used for current value detection of various electronic devices. It is useful when applied to a chip resistor or the like as a body.

11a, 11b A pair of electrode terminals 12 First resistor 13 Second resistor 14 Insulating layer 14a Insulating layer (high thermal conductive insulating layer)
15 Slit 16 A pair of end face electrodes

Claims (11)

A pair of electrode terminals; a first resistor that bridges between the pair of electrode terminals; a second resistor; and an insulating layer that covers the first resistor and the second resistor; A chip resistor in which a first resistor is connected to the upper surfaces of the pair of electrode terminals, and the second resistor is connected to the lower surfaces of the pair of electrode terminals. The chip resistor according to claim 1, wherein a resistance value of the first resistor between the pair of electrode terminals is different from a resistance value of the second resistor. The chip resistor according to claim 1, wherein a slit is formed in at least one of the first resistor and the second resistor. The slit is formed in the first resistor and the second resistor, and the slit formed in the first resistor and the slit formed in the second resistor are viewed from above. 4. The chip resistor according to claim 3, wherein the chip resistor is provided at different positions. The chip resistor according to claim 2, wherein a slit is formed only in the first resistor. A pair of end surface electrodes are formed on end surfaces of the first resistor, the second resistor, and the insulating layer, and the pair of end surface electrodes are formed on the upper surface of the first resistor and the second resistor. 2. The chip resistor according to claim 1, wherein the chip resistor is directly connected to both end portions of the lower surface. 2. The chip resistor according to claim 1, wherein the insulating layer formed between the first resistor and the second resistor is a high thermal conductive insulating layer having better thermal conductivity than the other insulating layers. vessel. The chip resistor according to claim 7, wherein the high thermal conductive insulating layer is made of resin and alumina or metal. The chip resistor according to claim 8, wherein the surface of the metal is oxidized. A pair of end surface electrodes are formed on end surfaces of the first resistor, the second resistor, and the insulating layer, and the pair of end surface electrodes positioned on the upper surface of the insulating layer on the upper surface of the first resistor. 2. The chip resistor according to claim 1, wherein a length of the pair of end surface electrodes positioned on a lower surface of the insulating layer on a lower surface of the second resistor is made longer than a length thereof. The chip resistor according to claim 1, wherein a metal layer is formed below the second resistor.