CN100481277C - Diffluence resistor and making method thereof - Google Patents

Abstract

The present invention provides a shunt resistor that can suppress the rise in surface temperature of a resistor and can be easily manufactured with a small number of parts. An insulating layer (3) is formed covering the upper surface (1a) of the resistor body (1). The two electrodes (5, 5) respectively have: a connecting portion (11) along the back side (1b) of the resistor body (1) and connected to the back side (1b); along the side of the resistor body (1) and along the insulating An extension (13) for heat dissipation extending from the surface of the layer (3). The ends of the extension parts (13) for heat dissipation of the two electrodes (5, 5) face each other on the insulating layer (3) with a gap (G) for trimming formed therebetween.

Description

Shunt resistor and manufacturing method thereof

technical field

The invention relates to a shunt resistor with large calorific value and a manufacturing method thereof.

Background technique

Patent Document 1 JP-A-2001-93701 Gazette (page 4, FIG. 1 )

As resistors that handle relatively large powers such as 1W and 2W, shunt resistors are known. For example, in the shunt resistor disclosed in Japanese Unexamined Patent Application Publication No. 2001-93701, a resistor main body having two electrodes at both ends of a plate-shaped metal resistor body is arranged in a ceramic case.

However, such a shunt resistor has a problem that when the surface temperature of the resistor body rises, the high-frequency characteristics of the shunt resistor are degraded, which affects the electrical characteristics of the shunt resistor.

Contents of the invention

An object of the present invention is to provide a shunt resistor capable of suppressing a rise in surface temperature of a resistor and easily manufactured with a small number of parts.

Another object of the present invention is to provide a method of manufacturing a shunt resistor that can easily mass-produce a shunt resistor that suppresses a rise in surface temperature of a resistor body using a small number of parts.

A shunt resistor to be improved by the present invention includes: a plate-shaped metal resistor body having an upper surface and a back surface; and at least two metal electrodes connected to the resistor body. In the present invention, the shunt resistor has an insulating layer covering the upper surface of the resistor, and at least one electrode has: a connection portion along the back surface of the resistor and connected to the back surface; Extended part for heat dissipation on the surface. In the present invention, the heat of the resistor is dissipated by the extended portion for heat dissipation, thereby suppressing a rise in the surface temperature of the resistor. Therefore, it is possible to prevent the occurrence of a situation affecting the electrical characteristics of the shunt resistor, such as a decrease in high-frequency characteristics. In particular, in the present invention, since part of the electrode is used to form the extended part for heat dissipation, it is possible to obtain a shunt resistor capable of suppressing an increase in the surface temperature of the resistor without increasing the number of components or increasing the number of work steps.

The number of electrodes, the number of electrodes forming the extended part for heat dissipation, and the size of the extended part for heat dissipation are arbitrary, but when the number of electrodes is two, it is preferable to respectively form the extended part for heat dissipation on the two electrodes so that the two heat dissipation The ends of the extended parts face each other on the insulating layer with a gap for trimming formed therebetween. In this way, the trimmed portion is formed by the gap between the ends of the heat dissipation extensions of the two electrodes, and the resistance value of the resistor can be easily adjusted. The trimmed portion can be formed by cutting with a grinding blade, irradiating a laser beam, or the like.

The shunt resistor of the present invention preferably further has a cover that covers the heat dissipation extension and is not electrically connected to the heat dissipation extension. In this way, the shunt resistor can be prevented from leaking by the cover. Of course, it is preferable to use a component that does not interfere with the heat dissipation effect of the heat dissipation extension part for such a cover. In addition, the cover may be provided in such a state that at least the back surface of the electrode is exposed. Specifically, the cover may have a shape that covers the extended portions for heat dissipation of the two electrodes and exposes the back surfaces of the two electrodes. Such a cover can be fixed on at least the heat dissipation extensions of the two electrodes using an adhesive.

The shunt resistor of the present invention preferably further has an insulating coating layer covering the back surface of the resistor body in a state where the connecting portion of the two electrodes is exposed. With such an insulating coating layer, it is possible to prevent the melting and diffusion of the semiconductor on the land pattern to come into contact with the resistor.

The shunt resistor of the present invention can be produced, for example, in the following steps. First, a pair of plate-shaped portions for forming electrodes are connected to both ends of the back surface of the resistor by welding (connection step), and the upper surface of the resistor is covered with an insulating layer before or after welding (insulation covering step). Then, the pair of electrode-forming plate-shaped portions are bent along the side surfaces of both end portions of the resistor and along the surface of the insulating layer (bending step). In this case, it is preferable to form a groove on the surface portion of the pair of plate-shaped portions for forming electrodes connected to the back surface of the resistor, the groove being located outside the corresponding side surface of the resistor, adjacent to the side surface and extending along the side surface. . If such grooves are formed, bending along the grooves in the bending step can be easily performed without damaging the pair of electrode-forming plate-shaped portions.

Description of drawings

1(A) and (B) are a top view and a right side view of a shunt resistor according to one embodiment of the present invention.

Fig. 2 is a sectional view along line II-II of Fig. 1(A).

3(A) to (G) are diagrams illustrating a method of manufacturing the shunt resistor shown in FIG. 1 .

FIG. 4 is a perspective view illustrating a test form of the shunt resistor shown in FIG. 1 .

5 is a cross-sectional view of a shunt resistor according to another embodiment of the present invention.

Symbol Description

1: Resistor; 3: Insulating layer; 5: Electrode; 7: Cover; 9: Insulating coating layer; 11: Connecting part; 13: Extended part for heat dissipation 101: Plate-shaped part for forming electrode; 102: Hoop ( hoop) component; 103: frame part; 105: insulating support part; G: gap.

Detailed ways

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

1(A) and (B) are a top view and a right side view of a shunt resistor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view along line II-II of FIG. 1(A). As shown in the drawings, the shunt resistor of this example has: a resistor body 1 ; an insulating layer 3 ; two electrodes 5 , 5 connected to the resistor body 1 ; a cover 7 and an insulating coating layer 9 . Resistor 1 has a rectangular plate shape having a surface (ie, upper surface) 1 a and a rear surface 1 b, and is formed of a copper alloy. The resistor body 1 of this example has a resistance value of 10 mΩ. The surface 1a of the resistor body 1 is covered with an insulating layer 3 made of a heat-resistant epoxy resin and having a thickness of about 0.05 mm or more. The two electrodes 5 , 5 are formed by nickel-plating copper plates, and are bent so as to each have a connection portion 11 and a heat dissipation extension portion 13 integrally formed with the connection portion 11 . Respective connection portions 11 , 11 of the two electrodes 5 , 5 are connected to the back surface 1 b of the resistor body 1 along the back surface 1 b of the resistor body 1 near two opposing sides of the rectangular resistor body 1 . In this example, as shown by the dotted line in Fig. 1, at five positions S ... arranged in a row along two opposite sides of the resistor body 1, the connection parts 11, 11 and the resistor body 1 are respectively connected by spot welding. The back side 1b is connected. The extended portion 13 for heat dissipation is bent to form a heat dissipation portion 15 extending along the surface of the insulating layer 3 and a side wall portion 17 along a pair of side surfaces of the insulating layer 3 and the resistor 1 . On the insulating layer 3 , respective ends of the two heat dissipation portions 15 , 15 are arranged facing each other with a gap G therebetween. In this way, the two heat sinks 15 , 15 face most of the surface 1 a of the resistor body 1 through the insulating layer 3 . The gap G has a width dimension through which the grinding blade for dressing can pass, and the resistor body 1 is trimmed by cutting with the grinding blade through the gap G in the manufacturing process. In addition, the gap G is filled with an adhesive 18 to be described later for fixing the cover 7 to the heat dissipation extension 13 .

The cover 7 is integrally formed of LPC liquid crystal resin, has a U-shaped cross section, and has a cover main body 19 and a pair of side walls 21, 21 standing from the edge portions of two opposing sides of the cover main body 19. The cover body 19 has a rectangular shape, covers the heat dissipation extension 13 and the adhesive 18 in the gap G, and is not electrically connected to the heat dissipation extension 13 . In addition, a protruding portion 19 a having a triangular cross-sectional shape protruding into the gap G between the heat dissipation portions 15 and 15 is formed on the back surface of the cover main body 19 . The pair of side walls 21 , 21 each have a rectangular shape and cover the two heat dissipation extensions 13 , 13 and the other pair of side surfaces of the insulating layer 3 and the resistor 1 . In this way, the cover 7 has a shape in which at least the rear surfaces of the connection parts 11 and 11 are exposed. The cover 7 is fixed to the extension part 13 for heat dissipation using an epoxy-based adhesive.

The insulating coating layer 9 is formed by coating an insulating paint made of epoxy resin with strong heat resistance, so that the two connecting parts 11, 11 are exposed and cover the back surface 1b of the resistor body 1, and then buried The concave portion between the two connection portions 11 , 11 and the back surface 1 b covering the resistor body 1 . In the shunt resistor of this example, the heat of the resistor body 1 is dissipated by the extension part 13 for heat radiation, and the rise of the surface temperature of the resistor body 1 can be suppressed. Therefore, it is possible to prevent the occurrence of a situation affecting the electrical characteristics of the shunt resistor, such as a decrease in high-frequency characteristics. In particular, in the shunt resistor of this example, a part of the electrode 5 is used to form the extension part 13 for heat dissipation, so it is possible to obtain a surface temperature capable of suppressing the resistor body 1 without increasing the number of components and without increasing the number of work steps. rising shunt resistor.

The shunt resistor for this example is fabricated in the following steps. First, as shown in FIG. 3(A), a metal hoop member 102 having a plurality of electrode-forming plate-like portion pairs 101, 101 is prepared. The hoop member 102 integrally includes at least a continuous frame portion 103 and a plurality of pairs of connection portions 104, 104 for connecting a plurality of pairs of electrode-forming plate portions 101, 101 to the frame portion 103. The frame part 103 has: a main part 103a connecting the pair of electrode plate parts 101, 101; an auxiliary part 103b extending parallel to the main part 103a; and a connecting part 103c connecting the main part 103a and the auxiliary part 103b. Furthermore, the electrode-forming plate-shaped portion pairs 101, 101 are arranged in a region surrounded by the main portion 103a, the auxiliary portion 103b, and the connection portion 103c. In addition, grooves 101a... are formed on the surface portions where the pair of plate-shaped portions for electrodes 101, 101 are to be bent in a later process. In addition, protruding portions 101b and 103d that are close to each other through a gap are formed on the electrode-forming plate-like portion 101 and the main portion 103a, respectively. In addition, in this figure, only a part of the metal hoop member 102 is shown (two sets of plate-like portion pairs 101, 101 for forming electrodes), but a plurality of sets of forming electrodes can be formed on this metal hoop member 102. Pair 101, 101 with plate-shaped parts.

Then, as shown in FIG. 3(B), in a state where the pair of plate-like portions 101 and 101 for forming electrodes are electrically insulated, insulating support portions 105 supported by the frame portion 103 are respectively formed to cover the protruding portions 101b and 103d. Then, as shown in FIG. 3(C) , the resistor 1 is arranged to straddle between a pair of opposite end portions of the electrode-forming plate-shaped portion pair 101 , 101 . A pair of end portions and the back surface of the resistor body 1 are joined together by spot welding.

Then, as shown in FIG. 3(D), an insulating paint is applied to the surface of the resistor 1 to form an insulating layer 3 . Then, as shown in FIG. 3(E), the electrode-forming plate-shaped portion pair 101,101 is cut away from the pair of connection portions 104,104. Then, the auxiliary portion 103b is removed from the frame portion 103 . Afterwards, the pair of plate-shaped portions 101, 101 for forming electrodes is bent along the grooves 101a, 101a so as to be along the side surface of the resistor 1 and the surface of the insulating layer 3, and the pair of plate-shaped portions 101, 101 for forming electrodes is bent. The ends of the two face each other with a gap G formed (FIG. 3(F)).

Then, as shown in FIG. 3(G), using a grinding blade, start from the upper surface of a part of the insulating layer 3 exposed between a pair of ends of the bent plate-like portion for forming electrodes 101, 101, and grind the insulating layer 3. The layer 3 and the resistor body 1 below the insulating layer 3 are cut, and trimming grooves 1c are formed on the resistor body 1 to adjust the resistance value. In this example, the pair of electrode-forming plate parts 101 and 101 are supported by the frame part 103 in an insulated state via the insulating support part 105 , so that resistance value adjustment can be performed while the frame part 103 supports the resistor. Then, the protruding portion 101b is cut off, and the support of the pair of electrode-forming plate-shaped portions by the insulating support portion 105 is released. Next, after fixing the cover 7 to the extension part 13 for heat dissipation with an adhesive, the insulating coating layer 9 is formed on a predetermined position on the back surface 1b of the resistor body 1, and the manufacture of the shunt resistor is completed.

Then, a shunt resistor (Example) of this example and a shunt resistor (Comparative Example) having the same structure as the shunt resistor of this example without the heat dissipation extension and the insulating layer were manufactured and tested. Specifically, as shown in Figure 4, in order to connect the copper patterns C1 and C2, each shunt resistor R is connected to the copper patterns C1 and C2 with solder, and the surface of the central part P of each shunt resistor after being energized at various powers is measured. Surface temperature at which the temperature is stable. Table 1 shows the measurement results.

Table 1

As can be seen from Table 1, the shunt resistor of this example can lower the surface temperature of the central portion compared to the shunt resistor of the comparative example.

In addition, in the shunt resistor shown in FIG. 1 , heat dissipation extensions 13 having approximately the same length are respectively formed on the two electrodes 5 and 5 , but the length dimensions of the respective heat dissipation extensions of the two electrodes are arbitrary. . In addition, of course, as shown in FIG. 5 , only one electrode 35B of the two electrodes 35A, 35B may be formed with the extended portion 43 for heat dissipation covering almost completely the resistor body 1 and the insulating layer 3 .

According to the present invention, the heat of the resistor body can be dissipated by the extended portion for heat dissipation, so that the rise in the surface temperature of the resistor body can be suppressed. Therefore, it is possible to prevent the occurrence of a situation affecting the electrical characteristics of the shunt resistor, such as a decrease in high-frequency characteristics. In particular, in the present invention, part of the electrode is used to form the extended portion for heat dissipation, so that a shunt resistor capable of suppressing the rise in surface temperature of the resistor body can be obtained without increasing the number of components and without increasing the work steps.

Claims (9)

1. A shunt resistor comprising: a plate-shaped metal resistor with an upper surface and a back surface; at least two metal electrodes connected to the resistor, characterized in that, having an insulating layer covering the upper surface of the resistor, At least one of the electrodes has: a connection portion along the back surface of the resistor and connected to the back surface; and an extension portion for heat dissipation extending along the side surface of the resistor and along the surface of the insulating layer. . 2. A shunt resistor comprising: a plate-shaped metal resistor with an upper surface and a back surface; at least two metal electrodes connected to the resistor, characterized in that, having an insulating layer covering the upper surface of the resistor, The two electrodes each have: a connection portion along the back surface of the resistor and connected to the back surface; a heat dissipation extension extending along the side surface of the resistor and along the surface of the insulating layer. department. 3. A shunt resistor comprising: a plate-shaped metal resistor with an upper surface and a back surface; at least two metal electrodes connected to the resistor, characterized in that, having an insulating layer covering the upper surface of the resistor, The two electrodes each have: a connection portion along the back surface of the resistor and connected to the back surface; a heat dissipation extension extending along the side surface of the resistor and along the surface of the insulating layer. department, Ends of the heat dissipation extensions of the two electrodes face each other on the insulating layer with a trimming gap formed therebetween. 4. The shunt resistor as claimed in claim 1, 2 or 3, characterized in that, A cover is further provided which covers the heat dissipation extension and is not electrically connected to the heat dissipation extension. 5. The shunt resistor of claim 4, wherein The cover is provided in such a state that at least the back surface of the electrode is exposed. 6. shunt resistor as claimed in claim 2 or 3, is characterized in that, It further has a cover having a shape that covers the extended portion for heat dissipation of the two electrodes and exposes the back surfaces of the two electrodes, The cover is fixed to at least the heat dissipation extensions of the two electrodes using an adhesive. 7. The shunt resistor as claimed in claim 2 or 3, characterized in that, It also has an insulating coating layer that covers the rear surface of the resistor in a state where the connecting portion of the two electrodes is exposed. 8. A method of manufacturing a shunt resistor, the shunt resistor comprising: a plate-shaped metal resistor body having an upper surface and a back surface; a pair of metal electrodes connected to the resistor body, the manufacturing method is characterized in that Has the following procedures: A connecting step: connecting a pair of electrode-forming plate-like portions to both ends of the back surface of the resistor by soldering; Insulation covering process: before or after the welding, covering the upper surface of the resistor with an insulating layer; Bending step: bending the pair of electrode-forming plate-shaped portions along the side surfaces of both end portions of the resistor and along the surface of the insulating layer. 9. the manufacture method of shunt resistor as claimed in claim 8 is characterized in that, Grooves are formed on the surface portions of the pair of plate-shaped portions for forming electrodes connected to the back surface of the resistor body, and the grooves are located outside the corresponding side surfaces of the resistor body and are separated from the resistor body. flanked by and extending along said sides, In the bending step, bending is performed along the groove.

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