JP6287820B2 - Surface mount inductor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surface mount inductor and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, surface mount inductors in which a coil is incorporated in an element containing a magnetic material have been widely used. For example, Patent Document 1 discloses a method for manufacturing a surface-mount inductor using a metal piece as an external terminal. In this method, the lead end of the coil is welded and joined to a metal piece, and the coil is sealed with a sealing material containing magnetic powder and resin to obtain an element body. The metal piece exposed from the element body was processed to form an external terminal.

  Patent Document 2 discloses a method for manufacturing a surface-mount inductor that does not use a lead frame but processes a lead end portion of a coil as an external terminal. In this method, a coil formed by winding a conducting wire having a flat cross section (hereinafter referred to as a flat wire) is sealed with a sealing material to obtain an element body.

JP 2003-290992 A JP 2004-193215 A

  Since the surface mount inductor disclosed in Patent Document 1 welds and joins the coil and the external terminal, mechanical stress and thermal stress are applied to the joint between the coil and the external terminal. Further, contact resistance is generated at the joint between the coil and the external terminal.

In the surface mount inductor disclosed in Patent Document 2, since the winding axis direction of the coil and the wide surface of the rectangular wire are perpendicular to each other, mechanical stress is applied to the inner and outer diameter portions of the coil when the coil is wound.
Further, in the surface mount inductor of Patent Document 2, one of the two lead ends of the coil is drawn from the bottom of the surface mount inductor toward the bottom of the element body, and the other lead end. Since the portion is drawn from the vicinity of the top surface of the surface mount inductor toward the bottom surface of the element body, the length of the lead end portion is different. Since the surface mount inductor with a built-in coil has different electrical characteristics when it is input to one external terminal and the electrical characteristic when it is input to the other external terminal, the marking indicating the polarity is printed on the surface. There are many cases to do.

  Therefore, the present invention reduces the thermal stress and mechanical stress on the coil, eliminates the contact resistance generated between the coil and the external terminal, and further has an electrical characteristic regardless of the input to any external terminal. An object of the present invention is to provide a surface-mount inductor and a method for manufacturing the same that do not change.

  The surface-mount inductor of the present invention includes a coil formed by winding a conductive wire, and an element body including two coils, and the coil includes a first winding portion in which a conductive wire having a flat rectangular cross section is wound; The second winding part wound and shifted to a position adjacent to the first winding part along the winding axis, and the second winding part so as to partially overlap the second winding part. And a third winding part wound at a position opposite to that of the first winding part, and pulling out the end of the conducting wire from the outer periphery of the first winding part and the third winding part The two coils built into the element body are characterized by the winding axis being parallel to the mounting surface of the element body and the surface of the pulling end part extending to the surface of the element mounting surface. It was.

According to the surface mount inductor and the manufacturing method thereof of the present invention, by using the lead end of the coil as an external terminal, thermal stress and mechanical stress on the coil are reduced, and further, between the coil and the external terminal. The generated contact resistance can be eliminated. In addition, since the winding axis direction of the coil and the wide surface of the coil are parallel, mechanical stress applied to the inner diameter portion and the outer diameter portion during winding can be reduced. Furthermore, since the distance from the lead-out position of the lead-out end of the built-in coil to the external terminal is the same on the left and right, the electrical characteristics remain the same regardless of which external terminal is used.
As described above, it is possible to provide a method for manufacturing a surface-mount inductor and a surface-mount inductor that reduce thermal stress and mechanical stress on the coil, suppress resistance, and have no polarity.

It is a perspective view of the coil used in the 1st example of the present invention. It is a figure which shows the winding method of the coil used in the 1st Example of this invention. It is a perspective view of the tablet used in the 1st example of the present invention. It is a top view of the mounting surface of the tablet used in the 1st example of the present invention. It is sectional drawing for demonstrating the manufacturing method of the surface mount inductor of the 1st Example of this invention. It is another sectional view for explaining the surface mount inductor manufacturing method according to the first embodiment of the present invention. It is a perspective view of the magnetic body core used in the 2nd Example of this invention. It is a perspective view which shows the surface mount inductor of the 2nd Example of this invention.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the coil 2 used for the surface-mount inductor of the first embodiment includes a first winding portion 2c wound in a single stage by a flat wire having an insulating coating, and a winding axis. Along the winding axis, the second winding portion 2d wound in one step while being shifted to a position adjacent to the first winding portion 2c and the second winding portion 2d partially overlaps with each other. And a third winding portion 2e wound in a single stage while shifting the position in the opposite direction to the first winding portion 2c. From the outer periphery of the first winding part 2d and the third winding part 2e, the lead-out end part 2b is drawn out, and the lead-out end parts 2b are perpendicular to the winding axis of the coil 2 and opposite to each other. And the end is bent. Since the coil 2 formed in this way is parallel to the winding axis direction and the wide surface 2a of the flat wire, no mechanical stress is applied to the inner and outer diameter portions during winding.

A winding method of the coil 2 will be described with reference to FIG. For winding the coil 2, a cylindrical winding portion 3a, a cylindrical wall portion 3b having a larger radius than the winding portion 3a, which is coaxially adjacent to the winding portion 3a, and a winding portion 3a, A rectangular wire having an insulation coating using a winding machine having a spindle 3 having a tip 3c which is a bottom surface opposite to the wall 3b and a jig 3d having a C-shaped opening at the tip. It is formed by winding.
As shown in FIG. 2A, the pair of spindles 3 are arranged in a state where the tip portions 3c face each other and contact each other. Next, as shown in FIG. 2 (b), the wide surface in the middle of the flat wire is brought into contact with the winding part 3a, and one end of the flat wire is wound as shown in FIG. 2 (c). A first winding portion 2c wound in one step is formed on the portion 3a. Next, as shown in FIG. 2 (d), the other end of the flat wire is shifted along the winding axis to a position adjacent to the first winding portion 2c, and the flat wire is wound in one step. 2 winding portions 2d are formed. Next, as shown in FIG. 2 (e), a jig 3d having a C-shaped opening is disposed on the end of the first winding part 2c on the second winding part 2d. In this state, the jig 3d is wound at a position opposite to the first winding part 2c so as to partially overlap the second winding part 2d, and the third winding part 2e is wound. Form. And the drawer | drawing-out edge part 2b is pulled out from the outer periphery of the 1st winding part 2c and the 3rd winding part 2e. The lead-out end portions 2b are each pulled out in the direction perpendicular to the winding axis of the coil 2 and opposite to each other, and the ends are bent. In this state, the coil 2 is heated, and as shown in FIG. 2 (f), the coil 2 can be manufactured by pulling apart the spindle 3 with the tips 3c in contact with each other.
The coil 2 is formed by winding in the order of the first winding portion → second winding portion → third winding portion, but is not limited to this. You may wind in order of 2nd winding part-> 3rd winding part-> 1st winding part, and wind the 2nd winding part after winding the 1st winding part to the middle. The order may be reversed, for example, by turning and then winding the first winding part and the third winding part.

The element body used in the first embodiment will be described. As shown in FIG. 3, the element body is formed by combining two tablets 4a. The tablet 4a is formed from a sealing material including a filler having metal magnetic powder and an epoxy resin.
The tablet 4a is a cube having an open end on one side surface, and has a space 4b for storing the coil 2 therein. A shaft 4c for insertion into the winding shaft of the coil 2 protrudes from the center portion of the inner wall of the surface facing the surface having the open end toward the surface having the open end. A shaft 4c inserted into the winding shaft of the coil 2 is formed in a cylindrical shape.
The upper surface or the bottom surface of the tablet 4a is the mounting surface 4e. As shown in FIG. 4, the mounting surface 4e has a rectangular shape. Of the four sides constituting the rectangle, a pair of facing sides including the side closest to the opening end is a short side, and the other side faces each other. A pair of sides is a long side. At both ends in the short side direction of the mounting surface 4e, elongated slits 4d for pulling out the lead-out end 2b of the coil 2 are provided.

Next, a method for sealing a coil will be described with reference to FIGS.
5A and 5B are cross-sectional views taken along the line AA of FIG. 4, and FIG. 5C is a plan view of the mounting surface 4e.
As shown in FIG. 5A, two coils 2 are arranged so that the first winding portions 2c face each other and become concentric shafts, and further, tablets 4a are arranged on both sides of the two coils 2, Arrange them so that the open ends face each other. At this time, the winding shaft of one coil 2 is inserted into the shaft 4c of one tablet 4a, and the leading end 2b of the coil 2 is pulled out in advance from the slit 4d of the mounting surface 4e. Next, as shown in FIG. 5B, the other tablet 4 a is fitted so that the tablet shaft 4 c is inserted into the air core of the coil 2 from the remaining end in the winding axis direction of the coil 2. . A space 4b for storing the coil 2 is provided inside the tablet 4a, and the two coils 2 are stored inside the two tablets 4a. The lead-out end portions 2b of the two coils 2 are each drawn out from one slit 4d in parallel with the short side of the mounting surface and inserted into the other slit 4d. Further, in this state, by heating and compressing them using a molding die, the surface of the lead-out end 2b of the coil 2 is exposed to the surface of the mounting surface 4e as shown in FIG. Then, the two tablets 4a are fixed in an embedded state, and the two coils 4 are pressed to form an element body 4 in which the two coils 2 are sealed.

Next, a method for processing the lead-out end 2b into an external terminal will be described with reference to FIG. FIG. 6 is a cross-sectional view taken along the line BB in FIG.
The leading end 2b whose surface is exposed / extended on the mounting surface 4e is irradiated with a laser on the wide surface 2a, and the insulating coating is peeled off. Since a rectangular wire is used, laser peeling conditions can be easily set, and all the external terminals are formed on the same surface, so that the process can be completed in one step. Next, Ni and Cr are simultaneously sputtered at a predetermined ratio on each lead-out end 2b to form a Ni—Cu layer, and then Sn is sputtered to form a Sn layer. Since a rectangular wire is used, the fixing strength is higher than that of the round wire, and the terminal flatness is also high. Further, from this state, the first winding portions are electrically connected to each other by sputtering Sn into a region including both the leading end portions 2b drawn from the first winding portions of the two coils 2. . Each sputtered lead end 2b may be used as an external terminal as it is, or a metal body may be further attached to serve as an external terminal.

Since the surface mount inductor manufactured in this way has the same distance from the left and right of the built-in coil lead-out end to the external terminal, the electrical characteristics are the same no matter which external terminal is used during use. Yes, no polarity. Therefore, it is not necessary to print markings indicating polarity, and one manufacturing process can be omitted, so that manufacturing costs can be reduced.
When the width of the jig is shortened, the distance between the first winding portion and the third winding portion is also shortened, so that the surface mount inductor can be reduced in size.
Further, a surface mount inductor having a high L value can be manufactured by electrically connecting two coils in series.
The arrangement of the two coils is not limited to the first embodiment, and the third winding portions may be adjacent to each other, or the first winding portion and the third winding portion are adjacent to each other. You may do it. Further, when the two coils are arranged adjacent to each other between the first winding parts or the third winding parts and connected in series, the shape of the winding part of the coil built in the element body is set. It can be left-right symmetric and magnetically left-right symmetric.
The coil is wound in the order of the first winding portion, the second winding portion, and the third winding portion, and then the drawing end portions are connected to each other, but is not limited thereto. After each winding part is wound individually, the respective leading ends may be electrically connected.

With reference to FIGS. 7 and 8, the surface-mount inductor of the second embodiment and the manufacturing method thereof will be described. Example 2 is a surface-mount inductor in which a coil is incorporated in an element body made of a magnetic core and a sealing material.
First, the coil 2 is formed by the same method as in the first embodiment. Thereafter, as shown in FIG. 7, a convex portion T to be inserted into the winding shaft of the coil 2, a slit S for pulling out the leading end portion 2b on the mounting surface, and an opening end side of the surface facing the mounting surface are provided. A pair of bottomed magnetic cores 6 a and 6 b having a hole H and a recess M formed in a surface adjacent to the mounting surface are attached to the coil 2. This pair of bottomed magnetic cores 6a and 6b is formed by inserting convex portions T into the winding shaft of the coil 2 from both sides in the winding axis direction of the coil and inserting the leading end portion 2b into the slit S. 2 is attached.
Further, the lead-out end 2b of the coil 2 housed in the pair of bottomed magnetic cores 6a, 6b is mounted on the mounting surface of the pair of bottomed magnetic cores 6a, 6b as shown in FIG. And it is bent along the magnetic cores 6a and 6b so as to extend to the surface adjacent to the mounting surface. The portion of the lead-out end 2b that extends to the surface adjacent to the mounting surface of the magnetic cores 6a and 6b is bent upward from the mounting surface of the magnetic cores 6a and 6b, and is formed on the mounting surface of the magnetic cores 6a and 6b. It arrange | positions in the dent M formed in the adjacent surface.
Subsequently, as shown in FIG. 8, the end of the lead-out end of the coil 2 disposed in the recess M formed on the surface adjacent to the mounting surface of the magnetic cores 6a and 6b is bonded to the adhesive B as shown in FIG. Fixed.
Furthermore, the magnetic cores 6a and 6b incorporating the coil 2 are arranged in a molding die with the mounting surfaces of the magnetic cores 6a and 6b facing upward, and a molding resin is placed in the molding die. Is filled. The mold resin is filled in the molding die so that the mounting surfaces of the magnetic cores 6a and 6b are exposed. At this time, since the magnetic cores 6a and 6b have the slits S and the holes H, the magnetic cores 6a and 6b can be sufficiently filled with the mold resin, and the slits of the magnetic cores 6a and 6b can be filled. The mold resin is filled up to the same plane as the mounting surface of the magnetic cores 6a and 6b in S.
Next, the mold resin is cured and taken out from the molding die so that the coil 2 is built in so that the winding axis is parallel to the mounting surface, and the lead-out end of the coil 2 is the mounting surface and mounting surface of the magnetic core. The entire surface is sealed with mold resin so that the mounting surface of the magnetic core is exposed, and the lead-out end of the coil extending to the surface adjacent to the mounting surface is sealed with mold resin. A stopped element is formed.
Then, the insulator coating of the portion extending on the mounting surface of the element body constituted by the mounting surface of the magnetic core is removed and used as an external terminal. At this time, an electrode is formed so as to cover a portion of the lead-out end portion of the coil 2 that extends to the mounting surface of the element body to constitute an external terminal.

As mentioned above, although the Example of the surface mount inductor of this invention and its manufacturing method was described, this invention is not limited to this Example. A part of the tablet may be replaced with a magnetic core, or a part of the magnetic core may be replaced with a tablet. The mounting surface of the magnetic core may be coated with a mold resin so that the surface of the coil drawing end is exposed. Furthermore, ferrite powder may be mixed with the mold resin.
In addition, a pair of metal bodies may be attached to the element body. The pair of metal bodies are formed so as to cover the upper surface and end surfaces of the element body and the side surfaces adjacent to both, and the lower end reaches the same surface as the surface of the external terminal formed on the mounting surface of the element body. The The pair of metal bodies are attached to both end faces of the element body so as to have a gap between the metal body and the surface of the external terminal. At this time, the metal body and the metal body are attached so as not to contact each other. The surface-mount inductor formed in this way can intrude the solder fillet into the gap formed between the metal body and the external terminal when mounted on the substrate and connected to the wiring pattern with solder, The surface mount inductor can be firmly fixed to the substrate. In addition, noise from the outside can be blocked.
Furthermore, in the second embodiment, the mounting surface of the magnetic core may be covered with a mold resin so that the surface of the lead-out end portion of the coil is exposed.

DESCRIPTION OF SYMBOLS 1 Surface mount inductor 2 Coil 2a Wide surface 2b Draw-out edge part 2c 1st winding part 2d 2nd winding part 2e 3rd winding part 3 Spindle 3a Winding part 3b Wall part 3c Tip 3d Jig 4 Element Body 4a Tablet 4b Space 4c Axis 4d Slit 4e Mounting surface 5 External terminals 6a, 6b Magnetic core T Protrusion S Slit H Hole M Recess B Adhesive

Claims (3)

  In a surface mount inductor including a coil formed by winding a conductive wire and an element body incorporating two of the coils, the coil includes a first winding portion wound with a conductive wire having a flat cross section, and a winding. Along the winding axis, a second winding portion wound and shifted to a position adjacent to the first winding portion along the axis, and a part of the second winding portion overlaps the second winding portion. A third winding portion wound in a position opposite to that of the first winding portion, the outer circumference of the first winding portion and the outer circumference of the third winding portion, respectively. The two coils incorporated in the element body are drawn out by pulling out the end of the conducting wire, and the winding axis is parallel to the mounting surface of the element body, and the surface of the lead end part is the surface of the element body. A surface-mount inductor characterized by extending to a surface of a mounting surface.   About the manufacturing method of the surface mount inductor provided with the coil formed by winding the conducting wire and the element body incorporating the two coils, the middle of the conducting wire having a flat cross section is brought into contact with the spindle of the winding machine. After forming the first winding portion, the second winding portion is formed by shifting the winding portion to a position adjacent to the first winding portion along the winding axis, and further forming the second winding portion. A jig is arranged on the first winding portion side on the winding portion, and the position is shifted in the opposite direction to the first winding portion so that a part of the jig overlaps with the second winding portion. Then, the jig is wound on the opposite side of the first winding portion to form a third winding portion, from the outer periphery of the first winding portion and the third winding portion, respectively. A step of drawing out two ends of the conductive wire to form a lead end, and a step of incorporating two of the coils into the element body. The surface mounting inductor is characterized in that the winding axis is parallel to the mounting surface of the element body and the surface of the leading end extends to the surface of the mounting surface of the element body. Method.   In a method of manufacturing a surface-mount inductor comprising a coil formed by winding a conductive wire and an element body incorporating two of the coils, winding is performed by bringing the middle of the flat conductive wire into contact with the spindle of the winding machine On the second winding part after forming the first winding part and the second winding part wound and shifted to a position adjacent to the first winding part along the winding axis. A jig is arranged on the first winding portion side of the first winding portion, and the third winding portion is wound on the second winding portion on the opposite side of the first winding portion of the jig. Forming a coil formed by pulling out the end portion of the conducting wire from the outer circumference of the first winding portion and the third winding portion to form a drawing end portion; and two coils, the first winding A step of incorporating the element into the element body in a state where the parts are opposed to each other, wherein the coil is disposed in the element body, the winding axis is parallel to the mounting surface of the element element, and the drawer is provided. Method for producing a surface-mount inductor, characterized in that the surface parts are formed so as to extend to the surface of the mounting surface of the plain body.

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