JP6287819B2 - 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, a coil drawing end portion is welded and joined to a metal piece, and the coil is sealed with a sealing material containing a magnetic body and a 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 pulled out from the vicinity of the top surface of the surface mount inductor toward the bottom surface of the element body, the distance from the lead-out position of the lead-out end portion to the external terminal is different on the left and right. Such a surface-mount inductor with a built-in coil has different electrical characteristics when input to one external terminal and electrical characteristics when input to the other external terminal. In particular, when used in a high-frequency circuit, the electrical characteristics may be significantly different depending on whether the coil drawing end is close to or far from the mounting substrate, so a marking indicating polarity is printed on the surface.

  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 and an element body incorporating the coil, and the coil includes a first winding portion in which a conducting wire having a flat cross section is wound, and a first winding along the winding axis. The second winding part wound at a position adjacent to the turning part and the second winding part in a direction opposite to the first winding part along the winding axis so as to partially overlap the second winding part A third winding part wound at a different position, and pulling out the end of the conducting wire from the outer periphery of the first winding part and the outer periphery of the third winding part to form a lead-out end, The shaft 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.

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 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.

  Embodiments of a surface-mount inductor and a manufacturing method thereof according to the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the coil 2 used for the surface mount inductor includes a first winding portion 2c wound in a single step with a flat wire having an insulating coating, and a first winding along the winding axis. A second winding portion 2d wound at a position adjacent to the portion 2c, and the first winding portion 2c along the winding axis so as to partially overlap the second winding portion 2d. And a third winding portion 2e wound with the position shifted in the opposite direction. From the outer periphery of the first winding part 2d and the outer periphery of the third winding part 2e, the lead-out end part 2b is drawn out, respectively, and the lead-out end part 2b is perpendicular to the winding axis of the coil 2 and is mutually It is pulled out in the opposite direction 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 wound in one step along the winding axis at a position adjacent to the first winding portion 2c, and the second winding portion 2d is 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 each pulled out from the outer periphery of the 1st winding part 2c, and the outer periphery of 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 shape of the jig is not limited to the C shape, and any other shape may be used as long as the flat wire cannot be wound around the portion in contact with the jig.
Further, by changing the thickness of the jig, the distance between the first winding portion and the third winding portion can be changed, and the length of the coil in the winding axis direction can also be changed. In order to easily adjust the thickness of the jig, a plurality of jigs of the same shape with a predetermined thickness may be prepared and used in a stacked manner. For example, when the distance between the second winding parts is set to 3 mm, the thickness of the jig can be easily adjusted without changing the process by using three jigs having a thickness of 1 mm. be able to. The jigs may be shaped so that the jigs fit each other so that they can be easily stacked and not easily displaced.

The element body used in the first embodiment will be described. The element body is formed by combining two tablets 4a as shown in FIG. 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 to Fig.5 (a), the tablet 4a is arrange | positioned so that an opening end may face both sides of the coil 2. As shown in FIG. At this time, the tablet shaft 4c is inserted into the winding shaft of the coil 2 in one tablet 4a, and the coil lead-out end 2b 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 coil 2 is stored inside the two tablets 4a. The lead-out end 2b of the coil 2 is drawn out from one slit 4d in parallel with the short side of the mounting surface, and is 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. The two tablets 4a are pressed and solidified to form the element body 4 in which the coil 2 is sealed.

Next, a method for processing the drawn end portion 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 and 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 the leading 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. It may be used as an external terminal as it is, or a metal body may be attached and used 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 second winding portions and the distance between the external terminals can be shortened, and the surface mount inductor can be reduced in size.

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. The pair of bottomed magnetic cores 6a and 6b are 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 2 and inserting the leading end portion 2b into the slit S. It is attached to the coil 2.
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.
The element body may be attached with a pair of metal bodies. 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 the coil, the coil includes a first winding portion wound with a conductive wire having a flat cross section, and a winding shaft. Along the winding axis so that a part of the second winding part overlaps with the second winding part and the second winding part wound at a position adjacent to the first winding part along the winding axis. And a third winding portion wound in a direction opposite to the winding portion of the first winding portion, and each of the conductors from the outer periphery of the first winding portion and the outer periphery of the third winding portion. The surface mount inductor is characterized in that the end of the lead is pulled out to be a lead end, the winding axis is parallel to the mounting surface of the element body, and the lead end extends to the surface of the mounting surface of the element body   About the manufacturing method of the surface mount inductor provided with the coil formed by winding conducting wire, and the element which built in the coil, the middle of the conducting wire having a flat cross section is wound in 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 part side on the part, and the position is shifted in the opposite direction to the first winding part so that a part of the jig overlaps the second winding part. A third winding part is formed by winding the jig on the opposite side of the first winding part, and the conductors are respectively connected from the outer circumferences of the first winding part and the third winding part. A coil is formed by pulling out the end of the coil, and a coil is built in the element. The coil is wound around the element and the winding shaft is included in the element. Mounting surface parallel to and manufacturing method of the surface mount inductor, characterized in that the withdrawal end portion is formed so as to extend to the surface of the mounting surface of the plain body.   In a method of manufacturing a surface-mount inductor comprising a coil formed by winding a conducting wire and an element body incorporating the coil, the middle of the conducting wire having a flat cross section is wound by contacting the middle of the conducting wire with the spindle of the winding machine. After forming the first winding portion and the second winding portion wound and shifted to a position adjacent to the first winding portion along the winding axis, the second winding portion on the second winding portion is formed. A jig is arranged on the side of the first winding part, and a third winding part is formed by overlapping and winding on the second winding part on the side opposite to the first winding part of the jig. A step of forming a coil as a lead end by pulling out the end of the conducting wire from the outer periphery of the first winding portion and the third winding portion, and a step of incorporating the coil in the element body, The coil is formed in the element body such that the winding axis is parallel to the mounting surface of the element body and the leading end extends to the surface of the element mounting surface. Method of manufacturing a surface mount inductor in symptoms.

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