JP2016025328A - Shunt resistor and mounting method thereof - Google Patents

Abstract

A shunt resistor that correctly recognizes a bonding position of a wire by a wire bonder and a mounting method thereof are provided. A shunt resistor bridges two electrodes 200 and is connected with a bonding wire for detecting a current value flowing between the electrodes based on a voltage between the electrodes. A pair of current terminals 10 that are electrically connected to the electrodes via the conductive adhesive 300 to input / output current and a bridge that extends between the two current terminals in a plate shape and crosslinks. Unit 20. Further, when one surface to which the bonding wire is connected is viewed from the front, and taken as a still image, at least one edge side 40a to 40c serving as the edge of the image is provided at a position where it does not overlap with the conductive adhesive in the bridge portion. As described above, the edge on the edge side has a larger edge strength than the edge generated between the current terminal and the conductive adhesive. [Selection] Figure 1

Description

  The present invention relates to a shunt resistor to which a bonding wire for detecting a current value flowing between electrodes is connected.

  Conventionally, when connecting a bonding wire to a shunt resistor, the connection position is determined after photographing one surface to which the bonding wire is connected with a camera or the like. Specifically, as described in Patent Document 1, based on a photographed image, an edge of a boundary line between one surface to which a bonding wire is connected and solder located thereunder is detected, and a shunt resistance is applied to the wire bonder. Recognize the position of the vessel. The wire bonder determines the position at which the wire is bonded with one point of the boundary line where the edge is detected as the origin.

JP 2014-78538 A

  However, when the reflectance of light of the solder and a part of the shunt resistor in contact with the solder (the first connection part in Patent Document 1) is close to each other or close to each other, the solder There is a possibility that the contrast between the first connection portion and the first connection portion is not sufficiently obtained, and the edge detection is not performed correctly. If the edge detection is insufficient, the wire bonder cannot correctly recognize the position of the shunt resistor, and there is a possibility that the origin necessary for determining the bonding position of the wire is wrong.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a shunt resistor in which a wire bonder can correctly recognize a bonding position of a wire, and a mounting method thereof.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

  In order to achieve the above-described object, the present invention is configured such that a bonding wire (400) for detecting a current value flowing between electrodes based on a voltage between the electrodes is connected by bridging the two electrodes (200). A shunt resistor, which is electrically connected to the electrode through a conductive adhesive (300), and is connected between a pair of current terminals (10) for inputting and outputting a current, and the two current terminals And a bridging part (20) extending in a plate shape and bridging, and when viewed as a still image when viewed from the front side to which the bonding wire is connected, does not overlap with the conductive adhesive in the bridging part At least one or more edge sides (40a to 40c, 50a to 50c, 60a) serving as the edges of the image are provided at the positions, and the edges on the edge sides are compared to the edges generated between the bridging portion and the conductive adhesive. The It is characterized in that the strength of the edge is large.

  According to this, the edge side is located at a position where it does not overlap with the conductive adhesive, and the edge strength of the edge side is larger than the edge generated between the current terminal and the conductive adhesive. Therefore, the position of the edge can be correctly recognized with respect to the wire bonder. Therefore, the wire bonder can correctly recognize the position of the origin necessary for determining the connection position of the bonding wire.

It is a perspective view which shows schematic structure of the shunt resistor concerning 1st Embodiment. It is a top view which shows a soldering process. It is a top view which shows an origin determination process and a 1st / 2nd coordinate determination process. It is a top view which shows a wire connection process. It is a perspective view which shows schematic structure of the shunt resistor concerning a modification. It is a top view which shows schematic structure of the shunt resistor concerning 2nd Embodiment. It is a perspective view which shows schematic structure of the shunt resistor concerning 3rd Embodiment. It is sectional drawing which shows the light source position at the time of imaging, and the position of a shadow. It is a perspective view which shows schematic structure of the shunt resistor concerning other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts. Further, the x direction, the y direction orthogonal to the x direction, and the z direction orthogonal to the xy plane defined by the x direction and the y direction are defined as directions. That is, the x direction, the y direction, and the z direction are linearly independent from each other.

(First embodiment)
First, a schematic configuration of the shunt resistor according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, this shunt resistor 100 has a surface along the xy plane, and electrically connects two electrodes 200 arranged in the x direction. The shunt resistor 100 described here connects one first electrode 200a and the other second electrode 200b.

  The shunt resistor 100 includes a pair of current terminals 10 connected to the electrode 200 via a solder 300 as a conductive adhesive, a bridging portion 20 that bridges between the current terminals 10, and a bridge between the current terminal 10 and the shunt resistor 100. An intermediary unit 30 that connects the unit 20 is provided.

  As shown in FIG. 1, the current terminal 10 includes a first terminal 10a connected to the first electrode 200a and a second terminal 10b connected to the second electrode 200b. The current terminal 10 has a planar shape along the xy plane, and a bonding wire (not shown) can be connected to the surface 11 opposite to the surface in contact with the solder 300. In addition, this surface may be described as one surface 11 to which a bonding wire is connected.

  The bridging portion 20 is a plate-like member along the xy plane, and extends in the x direction to electrically connect the first terminal 10a and the second terminal 10b. The bridging portion 20 is formed at a position higher than the current terminal 10 in the z direction. The bridging portion 20 and the current terminal 10 are integrally formed via the mediating portion 30. That is, the bridging part 20 and the first terminal 10a are connected via the first mediating part 30a, and the bridging part 20 and the second terminal 10b are connected via the first mediating part 30b. When the shunt resistor 100 is viewed from the front in the y direction, the shape thereof is substantially trapezoidal with the bridging portion 20 as an upper base and the mediating portion 30 as legs.

  The bridging portion 20 has an extending direction (x direction) of the bridging portion 20 in the bridging portion 20 when the one surface 11 to which the bonding wire is connected is viewed from the front, that is, when the shunt resistor 100 is viewed from the z direction. ) And at least one corner at a position where the solder 300 does not overlap. The corner portion in the present embodiment is a rectangular convex portion 40 protruding from the side portion 20a of the bridging portion 20 in the y direction.

  The convex portion 40 is composed of three sides. Specifically, it is composed of two sides 40a and 40b perpendicular to the side portion 20a of the bridging portion 20 and extending along the y direction, and a side 40c extending along the x direction. The intersection of the side 40a and the side 40c forms a corner (specifically 90 degrees) vertex A, and the intersection of the side 40b and side 40c forms a corner vertex B. The sides 40a, 40b, and 40c described here correspond to the edge sides described in the claims, and the points A and B correspond to the end points on the edge sides.

  In addition, this shunt resistor 100 is integrally formed with the current terminal 10, the bridging portion 20, the mediating portion 30, and the convex portion 40, and can be molded by a general method such as press working. .

  A wire bonder (not shown) is installed on the opposite side of the electrode 200 with respect to the shunt resistor 100. The wire bonder images the shunt resistor 100 from the z direction, determines the connection position of the bonding wire based on a still image obtained by imaging, and connects the bonding wire to the surface along the xy plane of the current terminal 10.

  Next, the effect of the shunt resistor 100 according to the present embodiment will be described.

  By the way, since the solder 300 forms a so-called fillet shape, the solder 300 and the current terminal 10 are imaged adjacently in a plane in a still image taken from the z direction by a wire bonder. Therefore, when the reflectances of the solder 300 and the current terminal 10 are close to each other, the boundary line between the solder 300 and the current terminal 10 cannot be ensured. For this reason, it is difficult to detect an edge at the boundary line between the solder 300 and the current terminal 10, and there is a possibility that the origin necessary for determining the bonding wire connection position is erroneous.

  On the other hand, the shunt resistor 100 has a convex portion 40. The convex portion 40 is formed at a position in the bridging portion 20 that does not overlap the solder 300. For this reason, in the still image image | photographed from the z direction with the wire bonder, the solder 300 and the convex part 40 do not adjoin. Therefore, even if the reflectance of the solder 300 and the shunt resistor 100, and thus the convex portion 40, are close to each other, the sides 40a, 40b, and 40c can be edge sides that form the edge of the image. That is, the edges of the sides 40 a, 40 b, and 40 c are edges that have a greater edge strength than the edge that occurs between the current terminal 10 and the solder 300. Therefore, the wire bonder can correctly recognize one of the end points of the edge side as an origin necessary for determining the connection position of the bonding wire. Note that the edge strength indicates the magnitude of a change in the value of two pixel outputs across the boundary at the boundary between two adjacent regions. A high edge strength indicates that the difference between the two pixel outputs is large and the output gradient between the pixels is large. The greater the gradient, the greater the contrast.

  Furthermore, the bridging portion 20 in the present embodiment is formed at a position higher than the current terminal 10 in the z direction. In other words, the bridging portion 20 is located closer to the wire bonder than the current terminal 10. If the depth of field of the imaging device mounted on the wire bonder is adjusted to the convex portion 40 and the rear of the convex portion 40 is outside the depth of field when viewed from the wire bonder, the convex portion 40 is focused and convex. The back of the part 40 is in a blurred state. As a result, the sides 40a, 40b, and 40c become edge sides that form the edges of the image. Therefore, the wire bonder can correctly recognize one of the end points of the edge side as an origin necessary for determining the connection position of the bonding wire.

  Next, a mounting method of the shunt resistor 100 according to the present embodiment will be described with reference to FIGS.

  First, a soldering process is performed. The soldering process is a process of electrically connecting the shunt resistor 100 to the electrode 200 via the solder 300. As shown in FIG. 2, the first terminal 10 a of the shunt resistor 100 and the first electrode 200 a are welded with the solder 300 interposed therebetween. Further, the second terminal 10b of the shunt resistor 100 and the second electrode 200b are welded with the solder 300 interposed therebetween.

  Next, a bonding process is performed. This is a step of connecting the bonding wire 400 to the shunt resistor 100. The bonding process includes an origin determination process, a first coordinate determination process, a second coordinate determination process, and a wire connection process.

  The origin determining step is a step of determining the reference position for determining the connection position of the bonding wire 400, that is, the coordinates. In this step, first, the wire bonder photographs the shunt resistor 100 as a still image so that the one surface 11 connecting the bonding wires 400 can be seen from the z direction. Then, image processing is performed on the photographed still image. Specifically, edge detection is performed. The specific method of edge detection is not particularly limited, but the Canny method or the second order differential method is generally used. As described above, the edge detection process strongly detects edges in the sides 40a, 40b, and 40c corresponding to the edge sides. As shown in FIG. 3, the wire bonder determines, for example, the vertex A, which is the end point of the side 40a and the end point of the side 40c, as the origin.

  Next, a first coordinate determination step is performed. In this step, based on the coordinates of the origin A, the connection position P (first coordinate) of the first bonding wire 400a in the bonding wire 400 is stored in the wire bonder. In the present embodiment, as shown in FIG. 3, a point on the one surface 11 of the first terminal 10a is a first bonding wire at a position away from the origin A by a distance a in the y direction and a distance b in the x direction. The first coordinate P that is the connection position of 400a is determined.

  Next, a second coordinate determination step is performed. In this step, the connection position Q (second coordinate) of the second bonding wire 400b is stored in the wire bonder based on the coordinate of the first coordinate P. In the present embodiment, as shown in FIG. 3, a position that is a predetermined distance c away from the first coordinate P is determined as the second coordinate Q with the first coordinate P as a reference.

  Next, a wire connection process is performed. As shown in FIG. 4, based on the first coordinate P and the second coordinate Q stored in the wire bonder, the bonding wire 400 is electrically connected to each coordinate position.

  Through the above steps, the bonding wire 400 can be connected to the shunt resistor 100 connected to the electrode 200 at an accurate position.

  Note that the point selected as the origin is not limited to the point A, and the point B may be set as the origin. Further, the intersection of the side part 20a and the side 40a or the intersection of the side part 20a and the side 40b also corresponds to the end point of the edge side, and these points may be selected as the origin.

(Modification)
In the above embodiment, the configuration having the convex portions 40 as the corner portions has been described. However, the shape of the corner is not limited to a convex shape such as the convex portion 40, and a part of the corner is configured as an edge, and an end point on the edge is recognized as the origin. It only has to be.

  For example, as shown in FIG. 5, the corner may be a notch-shaped recess 50 formed in the side portion 20 a of the bridging portion 20. The concave portion 50 in this example is rectangular and is composed of three sides. Specifically, it is composed of two sides 50a and 50b perpendicular to the side portion 20a of the bridging portion 20 and extending along the y direction, and a side 50c extending along the x direction. The intersection of the side 50a and the side 50c forms a cornered vertex (specifically 270 degrees) C, and the intersection of the side 50b and the side 50c forms a cornered vertex D. The sides 50a, 50b, and 50c described here correspond to the edge sides described in the claims, and the points C and D correspond to the end points on the edge sides.

(Second Embodiment)
In 1st Embodiment and its modification, the corner | angular part demonstrated the example formed only in one side part 20a of the bridge | crosslinking part 20. As shown in FIG. However, the corner portion may be formed on the side portion 20b opposite to the side portion 20a, or may be formed on either the side portion 20a or the side portion 20b.

  In particular, in the present embodiment, as shown in FIG. 6, an example will be described in which corner portions are formed line-symmetrically with a virtual line L penetrating the bridging portion 20 in the x direction as an axis of symmetry. In the shunt resistor 110 according to the present embodiment, the convex portion 41 having the same shape as that of the first embodiment is formed on the side portion 20a, and the convex portion 42 is further formed on the opposite side portion 20b across the virtual line L. Is formed. The convex portion 41 and the convex portion 42 have a line-symmetric shape with respect to the virtual line L.

  Also in this embodiment, as in the first embodiment, the convex portion 41 or the convex portion 42 has an edge side and a cornered vertex, so that the origin for wire bonding is detected by edge detection. Can be determined. Further, since the shunt resistor 110 is symmetric with respect to the virtual line L, the shape of the shunt resistor 110 during imaging is greatly changed before and after the rotation even if the shunt resistor 110 is rotated 180 degrees in the xy plane. The shunt resistor 110 can be mounted without any problem. That is, the restriction on the direction of the shunt resistor 110 at the time of mounting can be relaxed.

(Third embodiment)
In 1st Embodiment and 2nd Embodiment, although the structure which has a corner | angular part (40,41,42,50) as an element which comprises a shunt resistor (100,110) edge side was demonstrated, an edge side is comprised. The element is not limited to being a corner. For example, as shown in FIG. 7, the shunt resistor 120 may have a hole 60 in the bridging portion 20.

  In such a configuration, the outline 60a that forms the open end of the hole 60 is an edge side. Specifically, in the outline 60 a of the hole 60, the orientation of the surface constituting the bridging portion 20 is discontinuous, and the strength of the edge is generated between the current terminal 10 and the solder 300. It can be larger than the edge.

  In particular, as shown in FIG. 8, if light from the light source 500 is applied obliquely with respect to the z direction, a shadow 60b can be generated in the bridging portion 20 by the hole 60, and the shadow 60b causes contrast. Can be emphasized. Therefore, the strength of the edge of the outline 60a in the hole 60 can be further increased.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the above-described embodiments, when the shunt resistors 100, 110, 120 are viewed from the front in the y direction, the shape forms a substantially trapezoidal shape with the bridging portion 20 as an upper base and the mediation portion 30 as legs. An example is shown. However, the present invention is not limited to this. For example, as illustrated in FIG. 9, the shunt resistor 130 may have a flat plate shape that does not include the mediation unit 30. The shunt resistor 130 in this example has a convex portion 43 that protrudes in the y direction from the side portion 20a of the bridging portion 20 as a corner portion.

  Moreover, in 1st Embodiment and 2nd Embodiment, although it showed about the structure which has the rectangular convex part 40,41,42 or the rectangular recessed part 50 as a corner | angular part, it does not need to be a rectangle. For example, the corner portion may protrude in a triangular shape from the side portion 20a of the bridging portion 20, or a notch may be formed in a wedge shape. In the third embodiment, an example in which the outline 60a of the hole 60 is the edge side is shown. However, it is not always necessary to have a hole, and the edge side may be drawn by laser printing. The edge side may be formed by applying a resist film. That is, at the bridging portion 20, there is at least one edge side that is an edge of the image at a position that does not overlap the solder 300, and the edge at the edge side is generated between the current terminal 10 and the solder 300. It is only necessary that the strength of the edge is larger than that of the edge.

DESCRIPTION OF SYMBOLS 10 ... Current terminal, 20 ... Bridge part, 30 ... Intermediary part, 40 ... Convex part (corner part), 40a-40c ... Edge side, 200 ... Electrode, 300 ... Solder (conductive adhesive)

Claims (8)

A shunt resistor to which a bonding wire (400) for detecting a current value flowing between the electrodes based on a voltage between the electrodes is connected by bridging between two electrodes (200),
A pair of current terminals (10) electrically connected to the electrodes via a conductive adhesive (300) for inputting and outputting current;
A bridging portion (20) extending between the two current terminals in a plate shape and bridging,
When one surface to which the bonding wire is connected is viewed from the front and taken as a still image,
At least one or more edge sides (40a to 40c, 50a to 50c, 60a) serving as image edges at positions where the cross-linking portion does not overlap with the conductive adhesive,
The shunt resistor according to claim 1, wherein an edge of the edge side has a larger edge strength than an edge generated between the current terminal and the conductive adhesive. When one side to which the bonding wire is connected is viewed from the front,
It is a side surface along the extending direction of the bridging portion in the bridging portion, and has at least one corner (40, 50) at a position where it does not overlap with the conductive adhesive,
The shunt resistor according to claim 1, wherein a cornered vertex of the corner portion is an end point of the edge side. When one side to which the bonding wire is connected is viewed from the front,
The shunt resistor according to claim 2, wherein the corner portion is formed in line symmetry with respect to the extending direction of the bridging portion.   The shunt resistor according to claim 2 or 3, wherein the corner portion is a rectangular convex portion (40) protruding from a side portion of the bridging portion.   The shunt resistor according to claim 2 or 3, wherein the corner portion is a notch-shaped recess (50) formed in a side portion of the bridging portion. When one side to which the bonding wire is connected is viewed from the front,
In the plane of the bridging portion that does not overlap with the conductive adhesive, it has at least one hole (60),
2. The shunt resistor according to claim 1, wherein a contour line (60 a) constituting an open end of the hole portion is the edge side. A mounting method of the shunt resistor according to any one of claims 1 to 6,
A soldering step of soldering the current terminals to the electrodes;
A bonding step of electrically connecting a first bonding wire and a second bonding wire of the bonding wires to the shunt resistor after the soldering step;
The bonding process includes:
An origin determining step for determining an origin for determining a first coordinate to which the first bonding wire is connected among the one surface to which the bonding wire is connected;
A first coordinate determination step for determining the first coordinate based on the origin after the origin determination step;
After the first coordinate determining step, a second coordinate determining step of determining a second coordinate having a predetermined distance from the first coordinate and connected to the second bonding wire;
A wire connecting step of connecting the first bonding wire to the position of the first coordinate and connecting the second bonding wire to the second coordinate after the second coordinate determining step;
The method of mounting a shunt resistor, wherein the origin is an end point of the edge side when one surface to which the bonding wire is connected is viewed from the front.   The shunt resistor mounting method according to claim 7, wherein the edge side is detected by edge detection in image processing.

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