Manufacturing method of resistance

Abstract

To provide a manufacturing method of a resistance for detecting a current with a small size and a high dimension accuracy.SOLUTION: A manufacturing method of a resistance for detecting a current, in which a resister body is laminated so as to be nipped by an electrode, and which has a structure where a pair of connection surfaces 202a and 203a that is connected to a circuit board, includes: steps 1 to 3 of nipping a resistance material 210 with an electrode material 200, and preparing a plate-like clad material having a lamination structure laminated to a height direction to one part or a whole part; a step 4 of forming a plurality of connection surfaces 202a and 203a by forming a slit 220 reached to the resistance material of the clad material by a rotational blade CT such as an abrasive wheel; and a step 5 of obtaining a plurality of shunt resistances having first to third electrode portions 201 to 203 from a clad material in which the slit 220 is formed by being cut into a one piece, and which includes an electrode material and the resistance material.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a resistor. [Background technology]

[0002] Resistors used for current detection are manufactured with a low resistance value (for example, 1 mΩ or less) in order to reduce power loss in the resistor. As a method for achieving a low resistance value, a structure in which a resistor is sandwiched between electrodes has been proposed (for example, see Patent Document 1). Also, a current detection resistor with a vertical structure used for detecting a relatively large current has been proposed (for example, see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-227360 A [Patent Document 2] JP 2020-178014 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to realize such a structure, Patent Documents 1 and 2 propose a method of joining the electrodes and the resistor with welding or a joining material, but these methods make it difficult to provide a small resistor with high dimensional accuracy.

[0005] Patent Document 1 discloses that in order to fabricate a resistor having a structure in which a resistive body is sandwiched between electrodes, a welding method is used to join each of flat surfaces 11a and 11b of resistive body 11 to electrodes 12 and 13, respectively. However, in the welding method, a welded portion called a bead is formed at the joining interface. Therefore, if resistive body 11 is not thick, it is difficult to join, and it is difficult to realize a miniaturized resistor.

[0006] Furthermore, in Patent Document 1, electrode 13 has a shape that extends in one longitudinal direction beyond resistor 11, and electrode 12 has a shape that extends in the other longitudinal direction while bending. With such a shape, it is difficult to realize a miniaturized resistor.

[0007] Patent Document 2 discloses a shunt resistor with a vertical structure that dissipates heat from a resistor to a wiring pattern on a circuit board via electrodes. However, in Patent Document 2, the shunt resistor is formed by joining a resistor 11 and an L-shaped electrode block 13, and therefore the smaller the size, the more difficult the joining becomes, making it difficult to realize miniaturization.

[0008] Furthermore, Patent Document 2 discloses a method of joining resistor 11 and electrode blocks 12, 13 by pressure welding or by using a bonding layer, but with such a joining method, it is difficult to join resistor 11 and electrode blocks 12, 13 with high dimensional accuracy while achieving miniaturization of the resistor.

[0009] A resistor having such a structure is mounted on a wiring pattern of a circuit board by soldering. Therefore, it is required that the joint surfaces 12a, 15a of the electrode blocks 12, 13 with the wiring pattern are at the same height. Therefore, it is necessary to increase the dimensional accuracy of not only the resistor 11 and the electrode blocks 12, 13, but also the dimensional accuracy of the joint between the resistor 11 and the electrode blocks 12, 13. However, it is difficult to increase the dimensional accuracy while miniaturizing the resistor.

[0010] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a method for manufacturing a resistor that is small and has high dimensional accuracy. [Means for solving the problem]

[0011] In one aspect, a method for manufacturing a resistor is provided, the resistor comprising an electrode and a resistive element, a laminated portion in which the resistive element is sandwiched between the electrodes, and a pair of connection surfaces for connection to a circuit board are provided on one side of the lamination direction. The method for manufacturing a resistor includes the steps of: preparing a plate-shaped clad material comprising an electrode material that becomes the electrode and a resistive material that becomes the resistive element, the plate-shaped clad material having a laminated structure in part or all of which is formed by sandwiching the resistive material between the electrode materials and stacking them in the height direction; and forming a slit that reaches the resistive material from one side of the height direction of the clad material to form the pair of connection surfaces.

[0012] In one embodiment, the process of preparing the clad material includes a process of preparing a plate-shaped electrode material having a recess and a plate-shaped resistive material that can be fitted into the recess, and a process of fitting the resistive material into the recess to join the electrode material and the resistive material. In one embodiment, the step of preparing the clad material includes the steps of preparing three or more plate-shaped electrode materials and a plate-shaped resistive material, and joining the electrode materials and the resistive materials.

[0013] In one embodiment, the step of preparing the clad material includes the steps of preparing two plate-shaped electrode materials and a plate-shaped resistive material, and joining the electrode materials and the resistive material. In one embodiment, the method for manufacturing a resistor further includes, after the step of preparing the clad material, a step of cutting the clad material into individual pieces. Effect of the Invention

[0014] Resistors are manufactured using clad materials having a laminated structure in which a resistive material is sandwiched between electrode materials. This manufacturing method allows for miniaturization of resistors while improving dimensional accuracy. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 illustrates one embodiment of a current sensing resistor mounted on a circuit board. [Diagram 2]FIG. 2 illustrates an embodiment of a shunt resistor. [Diagram 3] 1A-1D illustrate an embodiment of a method for manufacturing a shunt resistor. [Figure 4] 4(a) and 4(b) are diagrams showing other embodiments of the electrode material. [Diagram 5] 5(a) to 5(d) are diagrams showing an example of a process for forming slits. [Figure 6] 6(a) to 6(c) are diagrams showing other embodiments of the shunt resistor. [Figure 7] FIG. 4 is a diagram showing an example of forming a clad material by heating and pressing the plate materials before joining with a roller (step 3 in FIG. 3). [Figure 8] FIG. 4 is a diagram showing an example of forming a clad material by heating and pressing the plate materials before joining with a roller (step 3 in FIG. 3). [Figure 9] FIG. 1 illustrates a laser trimmed shunt resistor. [Figure 10] 11A to 11C are diagrams illustrating another embodiment of a method for manufacturing a shunt resistor. [Figure 11] 11A to 11C are diagrams illustrating another embodiment of a method for manufacturing a shunt resistor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and duplicated descriptions will be omitted. In the multiple embodiments described below, the configuration of one embodiment that is not particularly described is the same as the other embodiments, so duplicated descriptions will be omitted.

[0017] Fig. 1 is a diagram showing one embodiment of a current detection resistor mounted on a circuit board. As shown in Fig. 1, a current detection resistor 10 is mounted on a circuit board 30. A combination of the circuit board 30 and the current detection resistor 10 mounted on the circuit board 30 constitutes a mounting structure 100.

[0018] The current sensing resistor 10 is a resistor used to detect a current, and may be called a shunt resistor 10. Hereinafter, in this specification, the current sensing resistor 10 may be called a shunt resistor 10.

[0019] The circuit board 30 has a substrate 31 (e.g., a glass epoxy substrate, a ceramic substrate, a metal core substrate, etc.) and a first wiring pattern 32 and a second wiring pattern 33 as wiring (e.g., a conductive pattern such as copper foil) formed on one surface of the substrate 31. The first wiring pattern 32 and the second wiring pattern 33 extend in directions facing each other with a predetermined gap therebetween.

[0020] The shunt resistor 10 is connected to the first wiring pattern 32 and the second wiring pattern 33. In this state, a current flows through the circuit board 30 (see the arrows in FIG. 1). The direction of the current flow is not limited to the embodiment shown in FIG. 1. The current may flow in the opposite direction to the arrows in FIG. 1.

[0021] 1, the shunt resistor 10 is molded from an insulating material 19 such as resin. If the shunt resistor 10 has a vertical structure, there is a risk that the upper and lower electrodes may be short-circuited due to a solder fillet that occurs when the shunt resistor 10 is mounted.

[0022] In this embodiment, the insulating material 19 covering the side surfaces of the shunt resistor 10 prevents the formation of solder fillets, and as a result, can prevent short-circuiting between the upper and lower electrodes.

[0023] The shunt resistor 10 has a plating layer 18. In the embodiment shown in Fig. 1, the plating layer 18 is formed on the upper surface of the shunt resistor 10 exposed from the insulating material 19. Examples of plating that forms the plating layer 18 include Ni plating, Ag plating, Au plating, and Al plating. By forming such a plating layer 18, the shunt resistor 10 has a surface that is easy to wire bond.

[0024] 1, the mounting structure 100 has a connection wire 36 connected to the top surface of the shunt resistor 10 by wire bonding. A downstream potential for detecting the voltage at the shunt resistor 10 is output via the connection wire 36.

[0025] The mounting structure 100 has a first voltage terminal 34 and a second voltage terminal 35 formed on the substrate 31 of the circuit board 30. In order to detect the voltage across the shunt resistor 10, the first voltage terminal 34 is configured to lead the potential on the upstream side of the shunt resistor 10, and the second voltage terminal 35 is configured to lead the potential on the downstream side of the shunt resistor 10.

[0026] The first voltage terminal 34 is disposed with a predetermined gap between it and the second wiring pattern 33, and is connected to the first wiring pattern 32 via a connection wire 34a extending diagonally from the first voltage terminal 34. The second voltage terminal 35 is disposed with a predetermined gap between it and the first wiring pattern 32, and is connected to the plating layer 18 of the shunt resistor 10 via a connection wire 36.

[0027] The mounting structure 100 includes a current detection device (not shown) that calculates the value of a current flowing through the shunt resistor 10. The current detection device is configured to detect the voltage of the shunt resistor 10 based on the potentials output from the first voltage terminal 34 and the second voltage terminal 35, and to calculate the value of a current flowing through the shunt resistor 10 based on the detected voltage.

[0028] Fig. 2 is a diagram showing one embodiment of a shunt resistor. As shown in Fig. 2, the shunt resistor 10 includes an electrode 200 and a resistor 210. The electrode 200 is made of a highly conductive metal material such as copper (Cu). The resistor 210 is made of a metal material suitable for current detection such as a Cu-Ni type, a Cu-Mn type, or a Ni-Cr type.

[0029] The electrode 200 has a first electrode portion 201 and a second electrode portion 202 extending in the length direction of the shunt resistor 10, and a third electrode portion 203 connected to the first electrode portion 201 and extending in the height direction of the shunt resistor 10. The resistor 210 extends in the length direction of the shunt resistor 10 and is sandwiched between the first electrode portion 201 and the second electrode portion 202.

[0030] With such a structure, the shunt resistor 10 has a laminated portion 300 in which the electrode portions 201, 202 and the resistor 210 are laminated. More specifically, the first electrode portion 201 (or the second electrode portion 202), the resistor 210, and the second electrode portion 202 (or the first electrode portion 201) are laminated in this order in the height direction.

[0031] The shunt resistor 10 has a slit 220 formed between the laminated portion 300 and the third electrode portion 203. Therefore, the third electrode portion 203 is disposed adjacent to the laminated portion 300 with the slit 220 interposed therebetween.

[0032] The lower surfaces of the laminated portion 300 and the third electrode portion 203 are located at the same height. More specifically, the connection surface 202a of the second electrode portion 202 and the connection surface 203a of the third electrode portion 203 constituting the laminated portion 300 are disposed on the same plane.

[0033] The connection surface 202a is connected to the first wiring pattern 32, and the connection surface 203a is connected to the second wiring pattern 33 (see FIG. 1). In this manner, the shunt resistor 10 has a structure in which a pair of connection surfaces 202a, 203a for connection to the circuit board 30 are provided on one side in the stacking direction.

[0034] The shunt resistor 10 has connection surfaces 202a, 203a arranged on the same plane. Therefore, such a configuration allows the shunt resistor 10 to be mounted on the circuit board 30 with high precision, and improves the mountability of the shunt resistor 10.

[0035] The resistor 210 is disposed adjacent to the circuit board 30 (see FIG. 1) via the second electrode portion 202. Therefore, such a configuration allows the heat generated in the resistor 210 to be efficiently transferred to the board 30. The shunt resistor 10 having such a vertical structure has excellent heat dissipation performance.

[0036] 2, the symbols indicating the length of each portion of the shunt resistor 10 are as follows: The length of the second electrode portion 202 in the longitudinal direction is represented by symbol 1a. The length of the third electrode portion 203 in the longitudinal direction is represented by symbol 1b. The length (width) of the slit 220 in the longitudinal direction is represented by symbol 1d. Therefore, the sum of the electrode lengths 1a, 1b and the slit width 1d corresponds to the entire length of the shunt resistor 10.

[0037] The length of the third electrode portion 203 in the width direction is represented by the reference symbol 3g. The length of the width 3g of the third electrode portion 203 corresponds to the entire width of the shunt resistor 10.

[0038] The length (thickness) of the resistor 210 in the height direction is represented by the reference symbol 2c. The length (thickness) of the first electrode portion 201 in the height direction is represented by the reference symbol 2h. The length (depth) of the slit 220 in the height direction is represented by the reference symbol 2e. Therefore, in this embodiment, the sum of the electrode length 2h and the slit depth 2e corresponds to the overall height of the shunt resistor 10. The overall height of the shunt resistor 10 is represented by the reference symbol 2f.

[0039] For example, when the length (reference symbol 1a) of the second electrode portion 202 in the longitudinal direction is 2 mm, the length of a bead (that is, a welded portion) produced by general welding is about 0.2 to 0.5 mm in the height direction.

[0040] The welds are formed on the top and bottom surfaces of the resistor 210 (i.e., the joint surface 210a of the resistor 210 with the first electrode portion 201 and the joint surface 210b of the resistor 210 with the second electrode portion 202). Therefore, the thickness 2c of the resistor 210 including the welds is 1.0 mm or more. As a result, it is difficult to realize a miniaturized shunt resistor 10 with such a manufacturing method.

[0041] In this embodiment, the resistor 210 and the electrode 200 (more specifically, the electrode parts 201, 202) are bonded by thermal diffusion. Bonding by thermal diffusion is a technique in which the resistor 210 and the electrode 200 are brought into close contact with each other while applying pressure and heat, and the bonded parts are diffused to bond them. This type of bonding technique is called thermal diffusion bonding.

[0042] In this way, the resistor 210 and the electrode 200 are joined by thermal diffusion, so the shunt resistor 10 does not have a joining layer such as a welding bead, solder, or adhesive. Therefore, the thickness 2c of the resistor 210 (i.e., the overall height 2f of the shunt resistor 10) can be made thin. As a result, the shunt resistor 10 can be made compact.

[0043] Furthermore, in this embodiment, the shunt resistor 10 is manufactured by using a clad material having a laminated structure formed by thermal diffusion bonding of a resistance material and an electrode material. Therefore, unlike a method of bonding the electrode 200 and the resistor 210 with welding or a bonding material (see, for example, Patent Documents 1 and 2), the shunt resistor 10 can be manufactured with high dimensional accuracy. As a result, a shunt resistor 10 that is small and has high dimensional accuracy can be provided. Hereinafter, a method of manufacturing the shunt resistor 10 will be described with reference to the drawings.

[0044] Fig. 3 is a diagram showing one embodiment of a method for manufacturing a shunt resistor. As shown in step 1 of Fig. 3, a rectangular electrode material that becomes the electrode 200 (more specifically, the electrode portions 201, 202, and 203) and a plate-shaped resistive material that becomes the resistor 210 are prepared. In the embodiment shown in Fig. 3, the electrode portions 201, 202, and 203 are integrally molded members.

[0045] The electrode 200 as an electrode material has a recess 230 extending in the width direction of the shunt resistor 10 (see FIG. 2). The direction in which the recess 230 is formed corresponds to the long side direction of the rectangular electrode material (i.e., the electrode 200) (see FIG. 3). The resistor 210 as a resistive material has a shape that matches the shape of the recess 230 of the electrode material. The resistor 210 as a resistive material has a first bonding surface 210a bonded to the first electrode portion 201 and a second bonding surface 210b bonded to the second electrode portion 202. The first bonding surface 210a and the second bonding surface 210b are disposed on opposite sides to each other.

[0046] 3, a resistor 210 serving as a resistive material is fitted into a recess 230 of an electrode 200 serving as an electrode material. By fitting the resistive material into the recess 230, the first bonding surface 210a is brought into close contact with the first electrode portion 201, and the second bonding surface 210b is brought into close contact with the second electrode portion 202.

[0047] For example, a frame material (hoop material) is used for the electrode material and the resistor material. Examples of methods for forming the electrode material include wire drawing using a die and cutting using a rotary blade. The thickness of the electrode material (length in the stacking direction) corresponds to the overall height 2f of the shunt resistor 10. The length of the recess 230 in the stacking direction corresponds to the thickness 2c of the resistor 210. When the difference between the height 2f of the electrode material and the length 2c of the recess 230 in the stacking direction is small (for example, 2f / 2c≦2), or when the length 2c is short and the electrode length 1a is long (1a / 2c≧2), a method of cutting the electrode material is effective.

[0048] 4(a) and 4(b) are diagrams showing other embodiments of the electrode material. As shown in FIG. 4(a), the electrode 200 as the electrode material may be composed of two plate-shaped electrode materials. In the embodiment shown in FIG. 4(a), the electrode parts 202 and 203 are integrally molded members and constitute a single electrode material. The electrode 200 as the electrode material has an electrode member 201A different from the electrode parts 202 and 203.

[0049] In this way, the electrode 200 may be composed of an electrode material corresponding to the electrode portions 202 and 203, and an electrode material corresponding to the electrode portion 201. In one embodiment, the electrode portion 201 and a portion 203X of the electrode portion 203 are integrally molded members, and the electrode portion 202 and a portion 203Y other than the portion 203X of the electrode portion 203 are another integrally molded member, and may be composed of different members. In this way, the electrode portion 203 is composed of two separate, separate integrally molded members (203X, 203Y).

[0050] As shown in Fig. 4(b), the electrode 200 as an electrode material may be composed of three (or four or more) plate-shaped electrode materials. In the embodiment shown in Fig. 4(b), the electrode 200 has an electrode member 201A corresponding to the first electrode portion 201, an electrode member 202A corresponding to the second electrode portion 202 and the other portion 203Y of the third electrode portion 203, and an electrode member 203A corresponding to a portion 203X of the third electrode portion 203 other than the other portion 203Y.

[0051] In general, in butt welding methods such as laser welding, the joint surfaces of the resistor and the electrode need to be flattened so that they can be in close contact with each other. In other words, in commonly used slit processing and round wire crushing processing, the joint surfaces of the resistor and the electrode are cut surfaces and do not form a strict flat surface, so the joint surfaces need to be flattened. Such flattening is an additional process and is a factor in increasing manufacturing costs.

[0052] On the other hand, in this embodiment, the bonding surfaces 210a, 210b of the resistor 210 are rolled surfaces formed when manufacturing the resistance material. In other words, the bonding surfaces 210a, 210b are not cut surfaces formed by metal processing such as slit processing or round wire crushing, and therefore have strict flat surfaces. Therefore, the resistor 210 can be bonded to the electrode 200 without performing additional processing on the resistance material.

[0053] In this way, without performing additional processing on the resistive material, the bonding surfaces 210a and 210b of the resistor 210 can be brought into close contact with the first electrode portion 201 and the second electrode portion 202, respectively. Therefore, the manufacturing cost of the shunt resistor 10 can be reduced.

[0054] Furthermore, by fitting the resistor 210 into the recess 230 of the electrode 200, a laminated section 300 is formed in which the resistor 210 is sandwiched and laminated between the electrodes 200 (more specifically, the first electrode portion 201 and the second electrode portion 202). In this embodiment, since the electrode 200 has a third electrode portion 203, the laminated section 300 is not formed over the entire shunt resistor 10 in the longitudinal direction of the shunt resistor 10, but is formed only over a portion of the shunt resistor 10.

[0055] In this embodiment, the shunt resistor 10 has a laminated structure as the laminated portion 300 in a part of the electrode 200 in the length direction. In one embodiment, the shunt resistor 10 may have a laminated structure as the laminated portion 300 in the entire electrode 200 in the length direction. A method for manufacturing the shunt resistor 10 having such a structure will be described later.

[0056] In this manner, by performing steps 1 and 2 in Fig. 3, a plate material before bonding is prepared, which has a laminated structure in part in which the resistor material is sandwiched between the electrode materials and the resistor 210 and the electrode 200 are laminated in the lamination direction (i.e., the height direction of the shunt resistor 10 in Fig. 2). Thereafter, as shown in step 3, the plate material before bonding is sandwiched between rollers R1 and R2. Thereafter, the plate material before bonding is pressed from above and below while being heated using rollers R1 and R2, thereby thermally diffusing and bonding the resistor 210 and the electrode 200. At this time, the plate material before bonding is pressed so that the deformation amount of the electrode material is 5% or less, for example.

[0057] The plate material before bonding is sandwiched between rollers R1 and R2, and while the rollers R1 and R2 are rotating, each of bonding surfaces 210a and 210b of resistor 210 is thermally diffusion bonded to each of electrode parts 201 and 202. For example, when the electrode material is copper, the plate material before bonding is heated to 750 to 900 degrees in a reducing or inert atmosphere to thermally diffuse bond the resistor material and the electrode material. In this manner, a thermally diffusion bonded clad material is prepared.

[0058] As a method for manufacturing the shunt resistor 10, the entire surface of the thermal diffusion bonded clad material may be surface-treated (for example, plating with Ni, Ni-P, Ni-PW, etc.). Such surface treatment can easily ensure that the shunt resistor 10 can be mounted on the circuit board 30 (for example, solder mounting or wire bonding). It is preferable to perform such surface treatment after step 3 and before step 4.

[0059] As shown in step 4 of FIG. 3, for example, a slit 220 is formed in the clad material using a rotary blade CT such as a grindstone, the slit 220 extending from one side of the height direction (the connection surface side as a shunt resistor) of the electrode 200 as the electrode material to the resistor 210 as the resistive material, thereby forming a pair of connection surfaces 202a, 203a.

[0060] In this way, by applying pressure and heat to the plate materials before joining with the rollers R1 and R2, it is possible to form a precise flat surface on the outer surfaces (the upper surface and connection surface as a shunt resistor) of the electrode parts 201 and 202 in the height direction. Furthermore, by forming a slit 220 in the clad material using the rotary blade CT, it is possible to form the connection surfaces 202a and 203a arranged on the same plane.

[0061] In step 4, the slit 220 is formed by cutting using a rotary blade CT so that the slit width 1d is shorter than the electrode lengths 1a, 1b (for example, electrode length 1a / slit width 1d≧1 (preferably about 2)).

[0062] In one embodiment, the slit 220 is formed so that the slit depth 2e is 4 / 5 or less of the height 2f of the shunt resistor 10. If the slit depth 2e exceeds 4 / 5 of the height 2f of the shunt resistor 10, the heat dissipation performance may decrease, and the current detection accuracy may decrease due to the temperature rise. Furthermore, in this case, the shunt resistor 10 has a structure that is vulnerable to pressure from above (for example, the pick-up pressure of the shunt resistor 10 when mounting the shunt resistor 10 on the circuit board 30). As a result, the reliability of the shunt resistor 10 may be impaired.

[0063] Thereafter, as shown in step 5 of Fig. 3, the clad material with the slits 220 formed therein is cut into individual pieces by means of pressing or the like. In this manner, by performing steps 1 to 5, a plurality of shunt resistors 10 are manufactured from the clad material having the electrode material and the resistive material. Note that the order of steps 4 and 5 may be such that step 5 comes first (step 4 comes later). In other words, the slits may be formed (step 4) after cutting into individual pieces (step 5).

[0064] The manufacturing method of the shunt resistor 10 including steps 1 to 5 can achieve the following effects. If the shunt resistor 10 having the connection surfaces 202a, 203a arranged at different heights is mounted on the circuit board 30, the connection between the connection surfaces 202a, 203a and the wiring patterns 32, 33 of the circuit board 30 may become unstable, and the shunt resistor 10 may not be able to fully perform its functions. As a result, the reliability of the shunt resistor 10 may be impaired.

[0065] According to this embodiment, the shunt resistor 10 is manufactured by using a clad material having a laminated structure in which a resistive material is sandwiched between electrode materials. This manufacturing method allows the shunt resistor 10 to be manufactured with high dimensional accuracy without using a large-scale construction method. As a result, the shunt resistor 10 can be made smaller and have improved dimensional accuracy.

[0066] As described above, the size of a welded portion by general welding is about 0.2 to 0.5 mm in the height direction, which is not suitable for resistor 210 having thickness 2c of 1.0 mm or less as in this embodiment. On the other hand, in the manufacturing method according to this embodiment, thickness 2c of resistor 210 can be made 1.0 mm or less, and thickness 2c of resistor 210 can be made, for example, about 0.1 to 1.0 mm.

[0067] In one embodiment, the shunt resistor 10 may have a second electrode site 202 with an electrode length 1a of 2 mm and a width 3g of 2 mm, a third electrode site 203 with an electrode length 1b of 1.5 mm and a width 3g of 2 mm, a slit width 1d of 1 mm, and a height 2f of 1.5 mm, which is the sum of the thickness of the first electrode site 201 of 0.35 mm, the thickness of the resistor 210 of 0.8 mm, and the thickness of the second electrode site 202 of 0.35 mm.

[0068] When a nichrome alloy (140 μΩ·cm) is used as the material of the resistor 210 and copper is used as the material of the electrode 200, the shunt resistor 10 may have the following dimensions: resistor 210 thickness 2c: 0.8 mm, second electrode portion thickness: 0.1 mm, electrode length 1a, 1b: 2.0 mm, slit width 1d: 1.0 mm, slit depth 2e: 0.9 mm, overall height 2f of the shunt resistor 10: 1.5 mm, overall width 3g of the shunt resistor 10: 2.5 mm

[0069] The shunt resistor 10 having such dimensions can obtain a resistance value of 200 μΩ. This shunt resistor 10 exhibits a thermal resistance of 2.0° C. / W or less, and even if a current of 200 A is applied, the temperature rise of the connection surface 202a can be suppressed to about 16° C. above the reference temperature.

[0070] The manufacturing method of the shunt resistor 10 in this embodiment includes many cutting steps. Such cutting steps are very effective when processing a small clad material, and allow the manufacture of a small (e.g., 2 to 5 mm) shunt resistor 10 with good dimensional accuracy and at low cost.

[0071] Figures 5(a) to 5(d) are diagrams showing an example of a process for forming a slit. The process for forming a slit 220 in a clad material by a rotary blade CT is called a dicing process (see step 4 in Figure 3). As shown in Figures 5(a) to 5(d), by using rotary blades CT having different sizes during the dicing process, slits 220 having different sizes can be formed, and the slit width 1d and / or slit depth 2e can be adjusted as desired.

[0072] The slit 220 according to the embodiment shown in Fig. 5(b) has a slit width 1d narrower than the slit width 1d shown in Fig. 5(a). The slit 220 according to the embodiment shown in Fig. 5(d) has a slit depth 2e deeper than the slit depth 2e shown in Fig. 5(c). In particular, in the embodiment shown in Fig. 5(d), the first electrode portion 201 has a depression 201a formed by the rotary blade CT. The depression 201a constitutes a part of the slit 220.

[0073] In this manner, by adjusting the slit width 1d and / or the slit depth 2e, the size of the electrode 200 (particularly, the electrode portions 202, 203) can be easily changed. Therefore, the shunt resistor 10 can easily correspond to the shapes of the wiring patterns 32, 33 of the circuit board 30.

[0074] Furthermore, the temperature coefficient of resistance (TCR), which is an index showing the rate of change in resistance value due to temperature, varies depending on the size of the slit 220. For example, if the slit depth 2e is deep, the TCR increases, and if the slit depth 2e is shallow, the TCR decreases. In this way, the TCR can be adjusted by adjusting the slit depth 2e.

[0075] 6(a) to 6(c) are diagrams showing other embodiments of the shunt resistor. As shown in FIG. 6(a), when performing step 4 of FIG. 3, a part of the resistor 210 may be cut by a rotary blade CT. In the embodiment shown in FIG. 6(a), the resistor 210 has a step 210c formed by the rotary blade CT. In this way, by cutting the resistor 210, the resistance value and TCR can be adjusted.

[0076] 6(b), the shunt resistor 10 has, as the slit 220, a first slit portion 220A and a second slit portion 220B connected to the first slit portion 220A. The first slit portion 220A is formed between the second electrode portion 202 and the third electrode portion 203. The second slit portion 220B is formed between the resistor 210 and the third electrode portion 203.

[0077] The second slit portion 220B has a slit width 1d wider than the slit width 1d of the first slit portion 220A. By forming the slit portions 220A and 220B in this manner, the resistance value and TCR can be adjusted.

[0078] An example of a method for forming the slit 220 having such a shape is as follows: First, when performing steps 1 and 2 in Fig. 3, the resistor 210 is loosely fitted into the recess 230 of the electrode 200 so that a gap wider than the thickness of the rotary blade is formed between the resistor 210 and the electrode 200.

[0079] In this state, the unbonded plate materials are thermally diffusion bonded to form a clad material (see step 3 in FIG. 3), and then the rotary blade CT is pressed against the clad material toward the gap between the resistor 210 and the electrode 200 to form a slit 220 (see step 4 in FIG. 3). By carrying out such a process, it is possible to form slits 220 (more specifically, slit portions 220A, 220B) having different slit widths 1d.

[0080] 6(c), the shunt resistor 10 has a first resistor portion 210A and a second resistor portion 210B adjacent to the first resistor portion 210A as the resistor 210. The slit 220 is formed between the first resistor portion 210A and the second resistor portion 210B.

[0081] The resistor parts 210A and 210B are formed by cutting the resistor part 210 with a rotary blade CT. The resistor 210 is completely divided by the rotary blade CT, and the slits 220 reach the first electrode part 201. By forming such resistor parts 210A and 210B, the resistance value and TCR can be adjusted.

[0082] Fig. 7 is a diagram showing an example of forming the clad material by heating and pressing the plate materials before bonding with rollers (step 3 in Fig. 3). As shown in Fig. 7, in a state in which the cross section of resistor 210 is arranged on the same plane as the cross section of electrode 200, the plate materials before bonding are pressed and heated with rollers R1 and R2, whereby each of electrode parts 201 and 202 is slightly crushed.

[0083] When the electrode portions 201, 202 are crushed, protruding portions 240A, 240B are formed on the electrode portions 201, 202, respectively. The protruding portions 240A, 240B are close to each other. Therefore, the distance between the first electrode portion 201 and the second electrode portion 202 is narrowed by the protruding portions 240A, 240B. In this case, when the shunt resistor 10 is mounted, there is a risk that a short circuit due to soldering will be caused by the protruding portions 240A, 240B.

[0084] Fig. 8 is a diagram showing an example of forming the clad material by heating and pressing the plate materials before joining with rollers (step 3 in Fig. 3). As described above, the clad material is pressed with rollers R1 and R2 so that the deformation amount of the electrode material becomes a predetermined amount (for example, 5% or less). Therefore, as shown in Fig. 8, it is preferable to make resistor 210 protrude from electrode 200 according to the deformation amount of the electrode material.

[0085] With this configuration, even if the electrode portions 201, 202 are crushed, the protruding portion 210d of the resistor 210 prevents the protruding portions 240A, 240B from approaching each other. As a result, the protruding portion 210b can ensure a space between the first electrode portion 201 and the second electrode portion 202, and can prevent a short circuit caused by soldering when the shunt resistor 10 is mounted.

[0086] On the other hand, if the amount of extension of the extension portion 210b is large, it increases the overall size of the shunt resistor 10. Therefore, it is preferable to keep the amount of extension of the extension portion 210b to 10% or less of the electrode length 1a.

[0087] 9 is a diagram showing a shunt resistor to be laser trimmed. As shown in FIG 9, the manufacturing method of the shunt resistor 10 may include a laser trimming process in which the side surface of the resistor 210 and the top surface or side surface of the electrode 200 are trimmed with a laser LZ.

[0088] For example, when a laser LZ is applied to a copper electrode material, the copper has a low laser absorption rate, so trimming may not be performed easily. Therefore, in order to facilitate trimming with the laser LZ, a protruding portion 210b that protrudes from the side of the resistor 210 may be formed. With this method, the protruding portion 210b formed on the resistor 210 can be irradiated with the laser LZ, and trimming can be performed easily.

[0089] As described above, the manufacturing method of the shunt resistor 10 may include a surface treatment step of the clad material. The surface treatment step of the clad material is preferably performed between step 3 and step 4 in FIG. 3. In this case, it is preferable to remove all of the plating film applied to the side surface of the resistor 210. With the plating film removed, the side surface of the resistor 210 is trimmed by a laser LZ, whereby the shunt resistor 10 can have a more stable resistance value.

[0090] Fig. 10 is a diagram showing another embodiment of a method for manufacturing a shunt resistor. In the embodiment shown in Fig. 10, the clad material has a sheet-shaped resistor 290 and a sheet-shaped electrode 200. The sheet-shaped electrode 200 is composed of a sheet-shaped first electrode member 260 and a sheet-shaped second electrode member 270. By sandwiching the resistor 290 between the electrode members 260 and 270, the clad material has a three-layer structure.

[0091] The sheet-like clad material having such a laminated structure is bonded by, for example, a fine clad bonding method. The fine clad bonding method is an example of thermal diffusion bonding. Unlike the cold pressure welding clad method, the fine clad bonding method is a method of bonding the clean surfaces of the resistor 290 and the electrode 200 by thermal energy without deforming the clad material. By using such a manufacturing method, a small shunt resistor 10 that requires high processing accuracy can be easily manufactured.

[0092] In the embodiment shown in FIG. 10, the manufacturing method of the shunt resistor 10 includes a step of dividing a clad material having a three-layer structure into the required size by a rotary blade CT (division step), and a step of forming a slit 220 by the rotary blade CT (slit formation step).

[0093] The order of the dividing step and the slit forming step is not particularly limited. The dividing step may be followed by the slit forming step, or the dividing step may be followed by the slit forming step. In the slit forming step, the resistance value or the TCR may be adjusted by adjusting the slit width 1d and / or the slit depth 2e, as in the above-mentioned embodiment.

[0094] Fig. 11 is a diagram showing another embodiment of a method for manufacturing a shunt resistor. In the embodiment shown in Fig. 11, the clad material includes a sheet-shaped electrode 200 (more specifically, a sheet-shaped first electrode member 260 and a sheet-shaped second electrode member 270), a plurality of plate-shaped resistors 290A, 290B, 290C, and 290D arranged between the first electrode member 260 and the second electrode member 270, and a plurality of plate-shaped electrode members 280A, 280B, 280C, and 280D.

[0095] Hereinafter, the plurality of resistors 290A to 290D may be referred to simply as resistors 290 without distinction. Similarly, the plurality of electrode members 280A to 280D may be referred to simply as electrode members 280 without distinction.

[0096] The resistors 290A-290D and the electrode members 280A-280D are arranged alternately in the length direction. The method for manufacturing the shunt resistor 10 includes a step of dividing the clad material by a rotary blade CT (division step) so as to form a pair of combinations having adjacent resistors 290 and electrode members 280, and a step of forming slits 220 by the rotary blade CT (slit forming step). In this embodiment, the order of the division step and the slit forming step is not particularly limited.

[0097] In the embodiment shown in Fig. 10, the clad material has a laminated structure as laminated section 300 having electrode 200 and resistor 210 over the entire electrode 200 in the length direction. In the embodiment shown in Fig. 11, the clad material has a laminated structure as laminated section 300 over a portion of electrode 200 in the length direction.

[0098] 10 and 11, the manufacturing method of the shunt resistor 10 may also include a step (surface treatment step) of performing surface treatment on both sides of the clad material (more specifically, the electrodes 200). By performing the surface treatment step, it is possible to easily perform surface treatment processing suited to the mounting method of the shunt resistor, such as wire bonding (Ni plating, Al plating), solder mounting (Sn plating), and sinter bonding (Au plating, Ni plating).

[0099] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0100] 10 Current sensing resistor (shunt resistor) 18 Plating layer 19 Insulation materials 30 Circuit Board 31 Substrate 32 First wiring pattern 33 Second wiring pattern 34 First voltage terminal 34a Connection wiring 35 Second voltage terminal 36 Connecting Wires 100 Mounting structure 200 electrodes 201 1st electrode part 201a Depression 202 2nd electrode part 202a Connection surface 203 3rd electrode part 203a Connection surface 203X Partial 203Y Other parts 210 Resistor 210a,210b joint surface 210c Stepped section 210d overhang 220 Slit 220A First slit section 220B Second slit section 230 Recess 300 Laminated section CT Rotary Blade LZ Laser

Claims

1. A method for manufacturing a resistor, comprising: an electrode; a resistor; a laminated portion in which the resistor is sandwiched between the electrodes; and a pair of connection surfaces for connection to a circuit board are provided on one side of the laminated portion, the method comprising the steps of: A step of preparing a plate-shaped clad material including an electrode material that becomes the electrode and a resistive material that becomes the resistor, the resistive material being sandwiched between the electrode materials and stacked in a height direction in a part or all of the plate-shaped clad material; and forming a slit extending from one side in a height direction of the clad material to the resistive material, thereby forming a pair of connection surfaces.

2. The step of preparing the clad material includes: A step of preparing the electrode material in a plate shape having a recess and the resistor material in a plate shape that can be fitted into the recess; The method for manufacturing a resistor according to claim 1 , further comprising the step of: fitting the resistive material into the recess to bond the electrode material and the resistive material to each other.

3. The step of preparing the clad material includes: A step of preparing three or more plate-shaped electrode materials and a plate-shaped resistance material; and joining the electrode material and the resistive material.

4. The step of preparing the clad material includes: A step of preparing two plate-shaped electrode materials and a plate-shaped resistor material; and joining the electrode material and the resistive material.

5. The method for producing a resistor according to claim 1 , further comprising the step of cutting the clad material into individual pieces after the step of preparing the clad material.

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