Patent Publication Number: US-2023146171-A1

Title: Manufacturing method of resistor and resistor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage of PCT/JP2020/048953 filed on Dec. 25, 2020, which claims priority of Japanese Patent Application No. JP 2020-011192 filed on Jan. 27, 2020, the contents of which are incorporated herein. 
     TECHNICAL FIELD 
     The present disclosure relates to a manufacturing method of a resistor, as well as to the resistor. 
     BACKGROUND 
     As resistors to be mounted on a substrate board, a resistor having a low resistance and a current path that is suitable for a high current measurement has been proposed (see JP2002-57009A). 
     SUMMARY 
     In recent year, as electronic devices are highly functionalized, there are increasing demands for a high-density mounting for circuit boards on which electronic components are to be mounted. However, in the resistor described in JP2002-57009A, it is difficult to further reduce its size while maintaining the dimensional accuracy, and so, there has been still a possibility for an improvement. 
     The present disclosure has been conceived in light of the above-described problem, and an object thereof is to reduce size of a resistor while ensuring a dimensional accuracy. 
     A manufacturing method of a resistor as an aspect of the present disclosure is a manufacturing method including: a step of forming a resistor base material by stacking an electrode material, a resistive material, and an electrode material in this order and by bonding the electrode material, the resistive material, and the electrode material by applying pressure in the stacked direction; a step of passing the resistor base material through a die, the die being formed with an opening portion having a dimension smaller than an outer dimension of the resistor base material; and a step of obtaining an individual resistor from the resistor base material passed through the die. 
     In addition, the resistor as an aspect of the present disclosure is the resistor to be mounted on a circuit board, and the resistor is provided with the resistive material, a first electrode material that is bonded to a first end surface of the resistive material, and a second electrode material that is bonded to a second end surface of the resistive material, wherein a surface of the resistor is formed with stripe-patterned grooves and ridges that extend in the direction orthogonal to the bonding direction in which the first electrode material, the resistive material, and the second electrode material are arranged. 
     According to these aspects, it is possible to reduce the size of the resistor while ensuring the dimensional accuracy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view for explaining a resistor according to a first embodiment of the present disclosure. 
         FIG.  2    is a perspective view for explaining the resistor according to a second embodiment of the present disclosure. 
         FIG.  3    is a perspective view of the resistor according to the second embodiment viewed from the side of a mounting surface for a circuit board. 
         FIG.  4    is a side view for explaining the resistor according to a first modification of the present disclosure. 
         FIG.  5    is a side view for explaining the resistor according to a second modification of the present disclosure. 
         FIG.  6    is a perspective view for explaining the resistor according to a third modification of the present disclosure. 
         FIG.  7    is a sectional view for explaining a state in which the resistor according to the third modification is mounted on the circuit board. 
         FIG.  8    is a schematic view for explaining a manufacturing method of the resistor according to the embodiment of the present disclosure. 
         FIG.  9 A  is a front view of a die used in Step (c) shown in  FIG.  8   , viewed from the upstream side in the drawing direction F. 
         FIG.  9 B  is a schematic view for explaining a step of processing a shape in the manufacturing method of the resistor according to the present embodiment. 
         FIG.  10    is a schematic view for explaining a step of adjusting size of a resistor base material to the size that allows insertion into the die in the manufacturing method of the resistor according to the present embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Explanation of Resistor 
     First Embodiment 
     A resistor  1  of a first embodiment according to the present disclosure will be described in detail with reference to  FIG.  1   .  FIG.  1    is a perspective view for explaining a structure of the resistor  1  according to the present embodiment. 
     The resistor  1  is provided with a resistive material  10 , a first electrode material  11 , and a second electrode material  12  and is formed by bonding the first electrode material  11 , the resistive material  10 , and the second electrode material  12  in this order. The resistor  1  is mounted on a circuit board, etc., which is not shown in  FIG.  1   . For example, the resistor  1  is arranged on a pair of electrodes that are formed on a land pattern of the circuit board. In the present embodiment, the resistor  1  is used as a current sensing resistor (a shunt resistor). 
     In the present embodiment, the direction in which the first electrode material  11  and the second electrode material  12  are arranged (the longitudinal direction of the resistor  1 ) is referred to as the X direction (the direction towards the first electrode material  11  is referred to as the +X direction, and the direction towards the second electrode material  12  is referred to as the −X direction). The width direction of the resistor  1  is referred to as the Y direction (the front side with respect to the plane of  FIG.  1    is referred to as the +Y direction, and the back side with respect to the plane of  FIG.  1    is referred to as the −Y direction), and the thickness direction of the resistor  1  is referred to as the Z direction. The X direction, the Y direction, and the Z direction are orthogonal with each other. 
     For the resistive material  10 , it is possible to use materials having low to high resistances according to the application. In the present embodiment, from the view point of sensing a large current at a high accuracy, it is preferable that the resistive material  10  be formed of a resistance body material having a low specific resistance and a small temperature coefficient of resistance (TCR). As examples, a copper-manganese-nickel alloy, a copper-manganese-tin alloy, a nickel-chromium alloy, a copper-nickel alloy, and so forth can be used. 
     In the present embodiment, although the resistive material  10  is formed to have a square shape from the view point of achieving a high-density mounting, the shape of the resistive material  10  may be a trapezoid shape. 
     The first electrode material  11  and the second electrode material  12  are preferably be formed of an electrically conductive material having a good electrical conductivity and thermal conductivity from the view point of ensuring a stable sensing accuracy. As one example, copper, a copper alloy, and so forth may be used as the first electrode material  11  and the second electrode material  12 . An oxygen-free copper (C1020) may preferably be used as the copper. The same material can be used for the first electrode material  11  and the second electrode material  12 . 
     The first electrode material  11  has an end surface having substantially the same shape as a first end surface of the resistive material  10 , and the first electrode material  11  is bonded to the first end surface of the resistive material  10  at this end surface. In addition, the second electrode material  12  has an end surface having substantially the same shape as a second end surface of the resistive material  10  that is on the opposite of the first end surface, and the second electrode material  12  is bonded to the second end surface of the resistive material  10  at this end surface. 
     In the present embodiment, a bonded portion  13  between the resistive material  10  and the first electrode material  11  and a bonded portion  14  between the resistive material  10  and the second electrode material  12  are both mutually bonded by a cladding (a solid phase bonding). In other words, bonded surfaces at the bonded portions  13  and  14  are respectively diffusion bonded surfaces in which metal atoms from both of the resistive material  10  and the respective electrode materials  11  and  12  are diffused to each other. 
     At the bonded portion  13  between the resistive material  10  and the first electrode material  11 , a boundary between the resistive material  10  and the first electrode material  11  has no step and is flat. In other words, the resistive material  10  and the first electrode material  11  form a smooth continuous surface. Similarly, also at the bonded portion  14  between the resistive material  10  and the second electrode material  12 , a boundary between the resistive material  10  and the second electrode material  12  has no step and is flat, and so, the resistive material  10  and the second electrode material  12  form a smooth continuous surface. In other words, the surfaces of the bonded portions  13  and  14  are formed so as to be flat over the entire circumference of the resistor  1  (the state in which the step is not formed). 
     From the view point of reducing the resistance value while ensuring the TCR (the temperature coefficient of resistance [ppm/° C.]), the ratio of a length LO of the resistive material  10 , the length L 1  of the first electrode material  11 , and a length L 2  of the second electrode material  12  in the length direction of the resistive material  10  can be set arbitrarily, and as one example, the ratio can be set so as to be L 1 :L 0 :L 2 =1:2:1. 
     Furthermore, from the view point of reducing the resistance value, the ratio of the length LO of the resistive material  10  relative to a length L of the resistor  1  (=L 1 +L 0 +L 2 ) can be equal to or less than 50%. 
     In the present embodiment, the resistor  1  has, on its surface, stripe-patterned grooves and ridges  15 . In the present embodiment, the stripe-patterned grooves and ridges  15  are formed on a mounting surface  16  of the resistor  1  for the circuit board and on an opposite surface  17  on the opposite side of the mounting surface  16 . In addition, the stripe-patterned grooves and ridges  15  are formed so as to extend over the width direction Y. The mounting surface  16  of the resistor  1  means an entire surface of the resistor  1  facing the circuit board. 
     In addition, the stripe-patterned grooves and ridges  15  are respectively formed, so as to extend over the width direction Y, on an opposite surface  11   a  on the opposite side relative to the bonded surface between the first electrode material  11  and the resistive material  10  and on an opposite surface  12   a  on the opposite side relative to the bonded surface between the second electrode material  12  and the resistive material  10 . 
     The surface roughness caused by the groove portions and the ridge portions of the stripe-patterned grooves and ridges  15  can be about from 0.2 to 0.3 μm in terms of arithmetic average roughness (Ra). 
     In the present embodiment, from the view point of adapting the resistor  1  to a high-density circuit board, the length L of the resistor  1  in the X direction can be equal to or shorter than 3.2 mm, and a length W of the resistor  1  in the Y direction can be equal to or shorter than 1.6 mm (product standard 3126 size or smaller). In addition, from the view point of achieving a handling property in a manufacturing method, which will be described below, for example, from the view point of preventing failure of a resistor base material forming a base of the resistor  1 , etc., the length L of the resistor  1  in the X direction can be equal to or larger 1.0 mm, and the length W of the resistor  1  in the Y direction can be equal to or larger 0.5 mm (product standard 1005 size or larger). 
     In addition, in the present embodiment, from the view point of achieving the low resistance, the resistance value of the resistor  1  is adjusted so as to be equal to or lower than 2 mΩ. In the above, the low resistance is a concept including the resistance value that is lower than the resistance value of general resistors. 
     In the present embodiment, all edge side portions P of the resistor  1  extending in the Y direction have chamfered shapes. In the present embodiment, from the view point of suppressing an electromigration caused at the edge side portions P and improving a heat cycle resistance, it is preferred that a radius of curvature of each edge side portion P be set so as to be R=0.1 mm or less. 
     Actions and Effects 
     Next, actions and effects in the first embodiment will be described. 
     In the present embodiment, the bonded portion  13  between the resistive material  10  and the first electrode material  11  and the bonded portion  14  between the resistive material  10  and the second electrode material  12  are respectively formed with the diffusion bonded surfaces in which metal atoms from both of the resistive material  10  and the respective electrode materials  11  and  12  are diffused to each other. With such a configuration, the resistive material  10  and the first electrode material  11  are firmly bonded with each other, and the resistive material  10  and the second electrode material  12  are firmly bonded with each other, and therefore, a good electrical property can be obtained. 
     In the present embodiment, the resistor  1  is formed to have the square shape. When the resistive material  10  has the square shape, the first electrode material  11  and the second electrode material  12  are respectively formed to have substantially the same shapes as the end surfaces of the resistive material  10  and respectively bonded to the end surfaces of the resistive material  10 , and a path of the current flowing from the first electrode material  11  and the second electrode material  12  through the resistive material  10  is formed linearly, and therefore, it is possible to stabilize the resistance value. In addition, in the resistor  1 , because the resistive material  10  is bonded between the electrode materials  11  and  12 , it is possible to adjust the resistance value while setting the volume of the resistive material  10  to the minimum required volume. 
     In addition, in the resistor  1 , the electron beam welding, for example, is not used for the bonding between the resistive material  10  and the first electrode material  11  and the bonding between the resistive material  10  and the second electrode material  12 , and therefore, the bonded portions  13  and  14  do not have beads (a welding mark having an irregular shape). Therefore, a bondability is not deteriorated even in a case in which wire bonding, etc. is performed on the surface of the resistor  1 . 
     In addition, in the present embodiment, surfaces of the bonded portions  13  and  14  are each formed so as to be flat over the entire circumference of the resistor  1 . Thus, at the time when the resistor  1  is to be mounted on the circuit board, etc., a capability to be sucked by a nozzle is increased for an operation of picking up the resistor  1  by suction by using the nozzle. Therefore, workability upon the mounting of the resistor  1  onto the circuit board is improved. 
     In the present embodiment, the stripe-patterned grooves and ridges  15  are formed so as to extend over the width direction Y on the mounting surface  16 , the opposite surface  17  on the opposite side of the mounting surface  16 , the opposite surface  11  a on the opposite side of the surface of the first electrode material  11  bonded to the resistive material  10 , and the opposite surface  12   a  on the opposite side of the surface of the second electrode material  12  bonded to the resistive material  10 . Therefore, a good viewability for the attachment direction and the attachment orientation for the resistor  1  is ensured for an operator handling the resistor  1  during the mounting on the circuit board. 
     The stripe-patterned grooves and ridges  15  are smoother than irregularities formed by the beads, and the deterioration of the bondability during the wire bonding is not caused. 
     In the present embodiment, the length L of the resistor  1  in the bonding direction (the X direction) is formed so as to be equal to or shorter than 3.2 mm, and the length W thereof in in the Y direction is formed so as to be equal to or shorter than 1.6 mm. In addition, the lengths are adjusted such that the resistance value of the resistor  1  is equal to or lower than 2 mΩ. 
     At this size, with general resistors in which the resistive material is welded with the electrode material, from the view point of ensuring the dimensional accuracy, for example, it is required to consider influences of the beads caused by the electron beam welding. However, the resistor  1  according to the present embodiment is formed by bonding the resistive material  10  with the electrode materials  11  and  12  by the diffusion bonding, and so, it is possible to design the resistor  1  so as to have the small size and the low resistance as described above. 
     In the present embodiment, the edge side portions P of the resistor  1  each has the chamfered shape. In general resistors, the resistors tend to be damaged due to occurrence of a phenomenon called the electromigration that is caused as a current density is increased in a non-chamfered corner portion, or due to concentration of thermal stress to such a corner portion in a similar manner. In addition, because the electromigration has a non-negligible influence as the circuit size is decreased, there was a concern that the smaller the resistor is, the more pronounced the electromigration becomes. 
     In contrast, in the resistor  1  according to the present embodiment, because the edge side portions P are chamfered, deviation of the current density in the edge side portions P is reduced. Thus, it is possible to suppress occurrence of the electromigration. In addition, in a similar manner, because the concentration of the thermal stress can be reduced, it is possible to improve the heat cycle resistance. 
     Therefore, with the resistor  1 , it is possible to reduce the size of the resistor while ensuring the dimensional accuracy. Thus, the resistor  1  can satisfy a demand in recent years for a high density to the circuit board, on which electronic components are to be mounted. In addition, because the beads are not formed on the bonded portions  13  and  14  between the electrode materials  11  and  12  and the resistive material  10 , it is easy to ensure a distance between the electrodes, and so, it is easy to reduce the resistance value. Therefore, the resistor  1  can also satisfy a demand for a high electric power. 
     Second Embodiment 
       FIG.  2    is a perspective view for explaining a resistor  2  according to a second embodiment of the present disclosure, and  FIG.  3    is a perspective view of the resistor  2  according to the second embodiment viewed from the side of the mounting surface for the circuit board. 
     The resistor  2  is provided with the resistive material  10 , a first electrode material  21 , and a second electrode material  22 . The resistive material  10 , the first electrode material  21 , and the second electrode material  22  are cladded with each other at bonded portions  23  and  24 . The resistor  2  has the first electrode material  21  and the second electrode material  22  with different shapes from those in the resistor  1  according to the first embodiment. 
     The first electrode material  21  is provided with a main body portion  31  that is bonded to the resistive material  10  and an extended portion  32  that extends from the main body portion  31  in the −Z direction. In addition, the second electrode material  22  is provided with a main body portion  41  that is bonded to the resistive material  10  and an extended portion  42  that is formed integrally with the main body portion  41  and that extends from the main body portion  41  in the −Z direction. 
     The main body portion  31  is provided with a protruded portion  311  that protrudes towards the resistive material  10  and that has an end surface with substantially the same shape as the first end surface of the resistive material  10  (on the +X direction side). In the main body portion  31 , the protruded portion  311  is bonded with the end surface of the resistive material  10  on the +X direction side so as to be abutted thereto. At the bonded portion  23  between the main body portion  31  and the resistive material  10 , the boundary between the resistive material  10  and the protruded portion  311  of the main body portion  31  has no step and is flat, and so, the resistive material  10  and the main body portion  31  form a smooth continuous surface. In other words, a surface of the bonded portion  23  is formed so as to be flat over the entire circumference of the boundary between the resistive material  10  and the main body portion  31  (the state in which the step is not formed). 
     The main body portion  41  of the second electrode material  22  is also configured in a similar manner as the main body portion  31 . In the main body portion  41 , a protruded portion  411  is bonded to the end surface of the resistive material  10  on the −X direction side so as to be abutted thereto. 
     Because the extended portion  32  extending in the Z direction is formed on the main body portion  31 , when the resistor  2  is to be mounted on the circuit board, it is possible to configure a leg portion, at which the extended portion  32  is bonded to the circuit board, by directing the extended portion  32  towards the circuit board. The extended portion  42  is also configured in a similar manner as the extended portion  32 . 
     In addition, in the present embodiment, in the resistor  2 , a mounting surface  51  of the resistor  2  for the circuit board, an opposite surface  52  on the opposite side of the mounting surface  51 , an opposite surface  21   a  on the opposite side of the surface of the first electrode material  21  bonded to the resistive material  10 , and an opposite surface  22   a  on the opposite side of the surface of the second electrode material  22  bonded to the resistive material  10  respectively have stripe-patterned grooves and ridges  50  extending over the Y direction that is orthogonal to the X direction. In the above, the mounting surface  51  means an entire surface facing the circuit board, and the mounting surface  51  includes not only the surfaces of the extended portions  32  and  42  on the circuit board side, but also the surface of the resistive material  10  on the circuit board side. 
     Actions and Effects 
     Next, actions and effects in the second embodiment will be described. 
     The bonded surfaces at the bonded portion  23  are respectively the diffusion bonded surfaces in which the metal atoms from the resistive material  10  and the electrode material  21  are diffused to each other. Therefore, even if the resistive material  10  and the first electrode material  21  are not welded by using the electron beam, they are firmly bonded with each other. In addition, the same applies to the resistive material  10  and the second electrode material  22 . Thus, it is possible to obtain the good electrical property for the resistor  2 . 
     In addition, with the resistor  2 , the following effects are afforded in addition to the viewability, the bondability, the capability to be sucked by the nozzle, the suppression of the electromigration, and the heat cycle resistance, which have been described as the effects afforded with the resistor  1  shown in  FIG.  1   . 
     In other words, because the first electrode material  21  and the second electrode material  22  respectively have the extended portions  32  and  42 , when the resistor  2  is to be mounted on the circuit board, the extended portions  32  and  42  can respectively configure the leg portions. Thus, when the resistor  2  is to be mounted on the circuit board, there is no need to provide an insulation configuration between the circuit board and the resistive material  10  in order to avoid contact between the resistive material  10  and the circuit board. 
     Modification 
     Next, a modification of the second embodiment will be described. 
     First Modification 
       FIG.  4    is a side view for explaining a resistor  3  according to a first modification of the present embodiment. 
     The resistor  3  is provided with a first electrode material  61  and a second electrode material  62  that are respectively bonded to the resistive material  10 . The first electrode material  61  is provided with a main body portion  63  that is bonded to the resistive material  10  and an extended portion  64  that is formed integrally with the main body portion  63  and that extends from the main body portion  63  in the −Z direction. In addition, the second electrode material  62  is provided with a main body portion  65  that is bonded to the resistive material  10  and an extended portion  66  that is formed integrally with the main body portion  65  and that extends from the main body portion  65  in the −Z direction. 
     The main body portion  63  is provided with a protruded portion  631  that protrudes towards the resistive material  10  and that has an end surface with substantially the same shape as the first end surface of the resistive material  10  (on the +X direction side). In the main body portion  63 , the protruded portion  631  is bonded with the end surface of the resistive material  10  on the +X direction side so as to be abutted thereto. In addition, the main body portion  65  is provided with a protruded portion  651  that protrudes towards the resistive material  10  and that has an end surface with substantially the same shape as the second end surface of the resistive material  10  (on the −X direction side). In the main body portion  65 , the protruded portion  651  is bonded with the end surface of the resistive material  10  on the −X direction side so as to be abutted thereto. 
     Although not shown in  FIG.  4   , an outer circumferential surface of the resistor  3  is also formed with the stripe-patterned grooves and ridges that extend over the Y direction. 
     In the first modification, the length L 0  of the resistive material  10  in the X direction is formed so as to be shorter than the length L 1  of the first electrode material  61  and the length L 2  of the second electrode material  62 . 
     In addition, a length dr of the resistive material  10  in the Z direction, the length dr of the main body portion  63  of the first electrode material  61 , and the length dr of the main body portion  65  of the second electrode material  62  in the resistor  3  are formed so as to be larger than the length dr of the resistive material  10 , the length dr of the main body portion  31  of the first electrode material  21 , and the length dr of the main body portion  41  of the second electrode material  22  in the Z direction of the resistor  2  of the second embodiment. 
     In addition, the length dl of the extended portions  64  and  66  in the Z direction is formed so as to be smaller, in other words, shorter than the length dr of the resistive material  10 , the main body portion  63 , and the main body portion  65  of the resistor  3 . 
     In addition, in the X direction, the length L 11  of the main body portion  63  of the first electrode material  61  and a length L 21  of the main body portion  65  of the second electrode material  62  are formed so as to be shorter than the length of each main body portion  31 ,  41  of the resistor  2  in the X direction. 
     By having such a configuration, even in a case in which the length L 0  of the resistance body is made shorter compared with the case in the second embodiment, because the first electrode material  61 , the resistive material  10 , and the second electrode material  62  are stacked in this order, and because the bonded surfaces are formed by a parallel bonding, it is possible to ensure the distance between the electrodes. Therefore, it is possible to achieve the resistor  3  with the low resistance while ensuring the distance between the circuit board and the mounting surface of the resistive material  10 . In addition, it is possible to improve a design flexibility of the circuit board on which the resistor  3  is to be mounted. 
     Second Modification 
       FIG.  5    is a side view for explaining a resistor  4  according to a second modification of the present embodiment. The resistor  4  is provided with a first electrode material  71  and the second electrode material  22  that are respectively bonded to the resistive material  10 . The first electrode material  71  is provided with a main body portion  73  that is bonded to the resistive material  10  and an extended portion  74 . In addition, a second electrode material  72  is provided with a main body portion  75  that is bonded to the resistive material  10  and an extended portion  76 . 
     The main body portion  73  is provided with a protruded portion  731  that has an end surface with substantially the same shape as the first end surface of the resistive material  10  (the +X direction side). In the main body portion  73 , the protruded portion  731  is bonded with the end surface of the resistive material  10  so as to be abutted thereto. In addition, the main body portion  75  is provided with a protruded portion  751  that has an end surface with substantially the same shape as the second end surface of the resistive material  10  (the −X direction side), and the protruded portion  751  is bonded with the end surface of the resistive material  10  so as to be abutted thereto. 
     Although not shown in  FIG.  5   , an outer circumferential surface of the resistor  4  is also formed with the stripe-patterned grooves and ridges that extend over the Y direction. 
     In the resistor  4 , the length of the extended portions  74  and  76  in the Z direction dl is formed so as to be larger than the length dr of the resistive material  10 , the length dr of the main body portion  73  of the first electrode material  71 , and the length dr of the main body portion of the second electrode material  72 . With such a configuration, compared with the first modification, it is possible to achieve the resistor  4  with the low resistance while increasing the gap between the circuit board and the mounting surface of the resistive material  10 . In addition, similarly to the first modification, it is possible to improve a design flexibility of the circuit board on which the resistor  4  is to be mounted. In this modification, it is possible to determine the length dl of the extended portions  64  and  66  in the Z direction by considering a TCR property and a high frequency property of the resistor  4 . 
     Third Modification 
       FIG.  6    is a perspective view for explaining a resistor  5  according to a third modification of the present embodiment. In addition,  FIG.  7    is a sectional view for explaining a state in which the resistor  5  is mounted on the circuit board. 
     The resistor  5  is provided with a first electrode material  81  and a second electrode material  82  that are respectively bonded to the resistive material  10 . The first electrode material  81  is provided with a main body portion  83  that is bonded to the resistive material  10  and an extended portion  84 . In addition, the second electrode material  82  is provided with a main body portion  85  that is bonded to the resistive material  10  and an extended portion  86 . 
     The main body portion  83  is provided with a protruded portion  831  that is bonded to the resistive material  10 . In addition, the main body portion  85  is provided with a protruded portion  851  that is bonded to the resistive material  10 . 
     Although the stripe-patterned grooves and ridges are also formed on an outer circumferential surface of the resistor  5  so as to extend over the Y direction, for the sake of simplification of the description, illustration thereof is omitted in  FIG.  6   . 
     In the resistor  5  according to this modification, in the Z direction, the length dl of the first electrode material  81  is larger than the length d 2  of the second electrode material  82  (d 1 &gt;d 2 ). 
     According to this modification, as shown in  FIG.  7   , in a case in which another semiconductor  93  is to be mounted between a land pattern  91 ,  92  formed on the circuit board and the extended portion  86  of the resistor  5  on one side, it is possible to design the resistor  5  such that the length dl of the first electrode material  81  is larger than the length d 2  of the second electrode material  82  in the Z direction. Thus, it is possible to compensate the thickness of the semiconductor  93  that is interposed between the resistor  5  and the circuit board, and it is possible to allow the protruded amount of the resistor  5  from the circuit board to fall into a predetermined value. In the resistor  5 , another semiconductor having a different thickness from the semiconductor  93  may be interposed between the extended portion  86  and the circuit board. 
     Explanation of Manufacturing Method of Resistor 
     Next, the manufacturing method of the resistors  1  to  5  according to the above-described embodiments will be described in detail with reference to  FIG.  8   . Because basic configurations of the manufacturing methods of the resistors  1  and  2  according to the above-described embodiments and the resistors  3 ,  4 , and  5  according to the modifications are the same, the manufacturing method of the resistor  2  will be described below. 
       FIG.  8    is a schematic view for explaining the manufacturing method of the resistor  2  according to the second embodiment. 
     The manufacturing method of the resistor  2  according to the second embodiment includes: Step (a) of preparing materials; Step (b) of bonding the materials; Step (c) of processing the shape; Step (d) of cutting out individual resistor; and Step (e) of adjusting the resistance value of the resistor by using a laser. 
     In Step (a) of preparing the materials, the resistive material  10  and the electrode materials  21  and  22  are prepared. The resistive material  10  and the electrode materials  21  and  22  are each a long wire rod having a flat rectangular shape. In the present embodiment, from the view point of the size, the resistance value, and a processability of the resistor, it is preferable to use a copper-manganese-nickel alloy and a copper-manganese-tin alloy as the material of the resistive material  10  and to use the oxygen-free copper (C1020) as the material of the electrode materials  21  and  22 . 
     In Step (b) of bonding the materials, the first electrode material  21 , the resistive material  10 , and the second electrode material  22  are stacked in this order, and the materials are bonded by applying pressure in the stacked direction, and thereby, a resistor base material  100  is formed. 
     In other words, in Step (b), a so-called cladding between dissimilar metal materials is performed. The bonded surface between the first electrode material  21  and the resistive material  10  subjected to the cladding and the bonded surface between the second electrode material  22  and the resistive material  10  subjected to the cladding are each the diffusion bonded surface in which metal atoms from both materials are diffused to each other. 
     Thus, it is possible to perform firm mutual bonding at the bonded surface between the resistive material  10  and the first electrode material  21  and at the bonded surface between the resistive material  10  and the second electrode material  22 , without performing the common electron beam welding. In addition, a good electrical property is obtained at the bonded surface between the resistive material  10  and the first electrode material  21  and at the bonded surface between the resistive material  10  and the second electrode material  22 . 
       FIG.  9 A  is a front view of a die  110  used in Step (c) shown in  FIG.  8    viewed from the upstream side in the drawing direction F. In addition,  FIG.  9 B  is a schematic view for explaining Step (c) of processing the shape in the manufacturing method of the resistor  2 . In  FIG.  9 B , the die  110  is shown in a sectional view taken along line B-B in  FIG.  9 A , and the resistor member  100  is shown in a side view. 
     In Step (c), the resistor base material  100  obtained by the cladding is passed through the die  110 . When the resistor  2  is to be manufactured, as one example, it is possible to use the die  110  shown in  FIG.  9 A . 
     An opening portion  111  is formed in the die  110 . The opening portion  111  has an inlet opening  112  that is set to have the dimension that allows the insertion of the resistor base material  100 , an outlet opening  113  that is set to have the dimension smaller than the outer dimension of the resistor base material  100 , and an insertion portion  114  that is formed to have a tapered shape from the inlet opening  112  towards the outlet opening  113 . In the present embodiment, the opening portion  111  is formed to have a rectangular shape in which corner portions are processed to have the chamfered shapes. 
     In addition, the die  110  having a protruded shape  110   a,  which protrudes towards the center of the opening on a part of any sides of the opening portion  111 , is applied. 
     By passing the resistor base material  100  through the die  110  having such a shape, it is possible to compressively deform the resistor base material  100  from all directions, and a groove  101  that continuously extends in the drawing direction F is formed in the resistor base material  100  by the protruded shape  110   a..    
     In addition, in the present embodiment, in Step (c), when the resistor base material  100  is passed through the die  110 , a drawing method in which the resistor base material  100  is drawn out by a holding tool  120  is applied. At this time, the stripe-patterned grooves and ridges are formed on the surfaces of the resistor base material  100  as sliding marks. 
     In Step (c), instead of employing the drawing processing in which the forming is completed by performing the drawing once, it may be possible to employ the drawing processing in which a plurality of dies respectively having the opening portions  111  with different sizes are prepared and the resistor base material  100  is passed through the plurality of dies in a consecutive manner. 
     In addition, in Step (c), by changing the shape of the opening portion  111  of the die  110 , it is possible to manufacture, for example, the resistor  1  without the extended portion, the resistors  3 ,  4 , and  5  respectively shown as the modifications, and so forth. 
     When the resistor  2  is to be manufactured, as one example, the die  110 , which has the shape protruding towards the center of the opening on a part of one side of the opening portion  111 , is applied. In the resistor base material  100 , the groove  101  that continuously extends in the drawing direction F is formed by the protruded shape  110   a  that is provided in the die  110 . 
     As the resistor base material  100  is cut into separate pieces, the groove  101  forms a recessed portion that is surrounded by the resistive material  10 , the main body portion  31  and the extended portion  32  of the first electrode material  21 , and the main body portion  41  and the extended portion  42  of the second electrode material  22 . 
     In Step (d) following Step (c), the resistor is cut out from the resistor base material  100  so as to achieve the size W in the width direction as designed. In addition, in the present embodiment, in Step (d), it is preferred that, the resistor base material  100  be cut from a surface  100   a  of the resistor base material  100 , in which the groove  101  is formed, towards an opposite surface  100   b.    
     Finally, in Step (e), the resistance value is adjusted as necessary by forming a cut out portion in a predetermined portion of the resistive material  10  of the resistor  2  by using the laser. 
     By following Steps (a) to (e) as described above, it is possible to obtain an individual piece of the resistor  1  from the resistor base material  100 . 
     Actions and Effects 
     Next, actions and effects in the present embodiment will be described. 
     With the manufacturing method according to the present embodiment, the first electrode material  21 , the resistive material  10 , and the second electrode material  22  are integrated by performing the cladding by stacking them and applying the pressure. By doing so, for example, it is possible to increase a bonding strength between the resistive material  10  and the respective electrode materials  21  and  22  without using the electron beam welding. 
     In addition, according to the manufacturing method according to the present embodiment, by compressing the resistor base material  100  from all directions by passing it through the die  110 , it is possible to form the external shape of the resistor base material  100  while ensuring the dimensional accuracy. Therefore, after the resistor base material  100  is formed, it is possible to manufacture the individual resistor  2  only by performing Step (d) shown in  FIG.  8   . 
     Therefore, it is possible to suppress individual differences caused when the resistor is manufactured by performing a plurality of processing steps. In addition, in the present embodiment, by passing the resistor base material  100 , which has been subjected to the cladding, through the die  110  to compress it from all directions, it is possible to further increase the bonding strength between the resistive material  10  and the respective electrode materials  11  and  12 . 
     As a method to compress the resistor base material from all directions, if the resistor base material is of a square shape, for example, there has been a method in which the resistor base material is subjected to a first pressure welding by using a pair of rollers that apply the pressure in the thickness direction Z, and thereafter, the resistor base material is subjected to a second pressure welding by using a pair of rollers that apply the pressure in the width direction (the Y direction). 
     However, with such a method, in the first pressure welding step, although the resistor base material is compressed in the thickness direction Z, the resistor base material is expanded in the width direction Y. In addition, in the following second pressure welding step, although the resistor base material is compressed in the width direction Y, the resistor base material is expanded in the thickness direction Z. As manufacturing errors are accumulated as described above, the dimensional accuracy is deteriorated, and individual variation for the resistor, variation in a temperature distribution when power is applied to the resistor, and so forth are increased. 
     In contrast, according to the manufacturing method in the present embodiment, by performing the drawing step in which the resistor base material  100  is passed through the die  110 , it is possible to uniformly compress the resistor base material  100  in the length-wise direction X and in the thickness direction Z. 
     Therefore, compared with a resistor base material obtained by repeating the compression from one direction and the compression from the other direction by using the rollers, it is considered that an electrically advantageous bonding interface is formed in the resistor base material  100 . Therefore, it is possible to ensure a reliability of the properties for the resistor  2  as an end product. 
     With the manufacturing method according to the present embodiment, especially, by using the plurality of dies  110  respectively having the opening portions  111  of different types in a consecutive manner, a compression forming is performed such that the size of the resistor base material  100  is reduced in a consecutive manner. Thereby, it is possible to uniformly compress the resistor base material  100  in the length direction X and in the thickness direction Z while reducing the load to the resistor base material  100  and the die  110 . Thus, it is possible to suppress differences in properties for the resistor  2  as the end product. 
     In addition, according to the manufacturing method according to the present embodiment, in Step (c) in which the resistor base material  100  is passed through the die  110 , by applying the drawing step, it is possible to increase the accuracy of the end product compared with an extruding method. By using this manufacturing method, it is possible to achieve a stabilization of the properties as the resistor  1 . 
     Especially, at least the outlet opening  113  of the opening portion  111  of the die  110  is formed with continuous curves. With such a configuration, it is possible to relieve a stress imparted while the resistor base material  100  is being passed through the opening, and so, it is possible to reduce the load to the resistor base material  100  and the die  110 . Thus, it is possible to suppress differences in properties for the resistor  1  as the end product. 
     In addition, because at least the outlet opening  113  is formed with the continuous curves, the corner portion of the resistor  1 , which is obtained by being passed through the die  110 , is rounded. Thus, it is possible to suppress the electromigration caused in the resistor  1  at the edge side portion P. In addition, it is possible to increase the heat cycle resistance of the resistor  1 . 
     In addition, according to the manufacturing method according to the present embodiment, because the first electrode material  21 , the resistive material  10 , and the second electrode material  22  are bonded with each other by the diffusion bonding, the welding beads are not formed. With the conventional bonding performed by the welding, as the size of the resistor is reduced, the non-negligible influence may be imparted to the resistance value by the welding beads. However, there is no such a concern for the resistors  1  to  5  obtained by the manufacturing method according to the present embodiment. 
     As described above, in the manufacturing method according to the present embodiment, the resistor base material  100  is obtained by cladding the resistive material  10  and the respective electrode materials  21  and  22 , and the resistor base material  100  is passed through the die  110  to perform the forming, and therefore, for example, it is possible to increase the bonding strength between the materials without using the electron beam welding, and it is possible to ensure a high dimensional accuracy. Thus, the manufacturing method is suitable for the manufacture of the resistors  1  to  5  having the small size. 
     When the resistor  2  is to be manufactured, in Step (d) shown in  FIG.  8   , it is preferred that the resistor base material  100  be cut from the surface  100   a  of the resistor base material  100 , in which the groove  101  is formed, towards the opposite surface  100   b.  By doing so, it is possible to cause the burr formed during the cutting to be received in a space within a groove (a recessed portion) on the mounting surface side. 
     In addition, in the manufacturing method according to the present embodiment, before performing Step (c) of processing the shape, a step of adjusting the size of the resistor base material  100 , which has been subjected to the cladding, to the size that allows the insertion thereof into the die  110  may be performed. 
       FIG.  10    is a schematic view for explaining the step of adjusting the size of the resistor base material  100  that is performed prior to Step (c). 
     In this step, as one example, as shown in  FIG.  10    (a), in order to make the resistor base material  100 , which has obtained through Step (b) of bonding the materials, insertable into the inlet opening  112  of the die  110 , both end portions of the resistor base material  100  at the direction orthogonal to the drawing direction F, in other words, portions outside dotted lines shown in  FIG.  10    (b) are cut off along the drawing direction F. 
     Next, as shown in  FIG.  10    (c), the resistor base material  100  is inserted to the die  110  after being processed to the size that is adapted to the inlet opening  112  of the die  110 . 
     As described above, by adding the step of adjusting the size of the resistor base material  100  before Step (c) of processing the shape, it is possible to prevent deviation of compressive stress applied to the resistor base material  100  that is caused when the resistor base material  100  is passed through the die  110 . In addition, thus, it is possible to suppress differences in properties for the resistor  1  as the end product. 
     Other Embodiments 
     The embodiments of the present disclosure as described above merely illustrate a part of application examples of the present disclosure, and the technical scope of the present disclosure is not intended to be limited to the specific configurations of the above-described embodiments. 
     For example, in  FIG.  2   , the end surfaces of the resistor  2  in the Y direction (the end surfaces of the electrode materials  21  and  22  in the Y direction) and the respective bonded surfaces between the resistive material  10  and the respective electrode materials  21  and  22  are shown so as to substantially orthogonally intersect with each other in the drawings. In addition, the side surface of the resistor  2  along the Y direction (the opposite surface  22   a  relative to the bonded surface between the resistive material  10  and the electrode material  21 ,  22 ) and the respective bonded surfaces between the resistive material  10  and the electrode materials  21  and  22  are shown so as to be parallel with each other. However, the relationships between the respective surfaces are not limited thereto. 
     In addition, the bonded surfaces between the resistive material  10  and the respective electrode materials  11  and  22  are shown with straight lines in  FIGS.  2  and  3   . However, because the bonded surfaces between the resistive material  10  and the respective electrode materials  11  and  22  are the diffusion bonded surfaces, in a microscopic scale, the resistive material  10  is not in close contact with each of the electrode materials  11 ,  11 ,  12  at a flat end surface. 
     In addition, in  FIG.  2   , the area of the resistive material  10  on the mounting surface  51  side may be larger than the area of the opposite surface  52  on the opposite side relative to the mounting surface  51 . In addition, Conversely, the area of the resistive material  10  on the mounting surface  51  side may be smaller than the area of the opposite surface  52  on the opposite side relative to the mounting surface  51 . In the side surface of the resistor  2  (in other words, a cross-section of the resistor base material  100 ), the bonded surfaces between the resistive material  10  and the respective electrode materials  21  and  22  may vary depending on the cross-sectional shape of the electrode material or the resistance body material prior to the cladding. 
     In the present embodiment, as the material of the resistive material  10  that is applied to the resistors  1  to  5 , a resistive material with high resistance may be used. By doing so, it is possible to reduce the size of the resistor while ensuring the resistance value of the resistor. 
     The present application claims a priority based on Japanese Patent Application No. 2020-011192 filed on Jan. 27, 2020 in the Japan Patent Office, the entire contents of which are incorporated herein by reference.