JP2016092096A - Manufacturing method of surface-mounted inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounted inductor in which contact resistance to be generated between a coil and an external terminal is eliminated by reducing a thermal stress/mechanical stress to the coil and the coil is formed symmetric bilaterally, the surface-mounted inductor encapsulating the coil with an encapsulation material including a magnetic powder and a resin, and a manufacturing method of the surface-mounted inductor.SOLUTION: The manufacturing method of the surface-mounted inductor includes the steps of: forming a coil 2 while using a winding machine which includes a pair of winding shafts for winding a lead wire and in which each of the winding shafts includes at least two winding portions with different outer diameters; and fitting a pair of tablets 4a from both ends of the coil 2 and forming a compact 4 incorporating the coil 2 by heating compression. The coil 2 is installed in the compact 4 in such a manner that a winding axis of the coil 2 is parallel with a mounting side 4e of the compact 4 and a surface of a lead-out end 2b is exposed on a surface of the mounting side 4e of the compact 4.SELECTED DRAWING: Figure 5

Description

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

  Conventionally, surface mount inductors in which coils are sealed with a sealing material having magnetic powder and resin 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 drawn end of a coil is welded and joined to a metal piece, and the coil is sealed with a sealing material to obtain a molded body. The metal piece exposed from the molded 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 a molded 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.
In the surface mount inductor disclosed in Patent Document 2, one of the two lead ends of the coil is drawn from the bottom surface of the surface mount inductor toward the bottom surface, and the other lead end is the surface. Since the mounting inductor is drawn from the vicinity of the top surface toward the bottom surface, the length of the leading end is different. For this reason, the shape of the coil is left-right asymmetric. A surface-mount inductor incorporating a left-right asymmetric coil has different electrical characteristics when input to one external terminal and electrical characteristics when input to the other external terminal. Such surface mount inductors often print markings indicating the polarity of the electrical characteristics.

  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, the surface mount inductor of the built-in coil shape is symmetrical. The purpose is to provide a manufacturing method.

  The present invention relates to a method for manufacturing a surface-mount inductor including a coil formed by winding a conductive wire and a molded body in which the coil is sealed with a sealing material including a resin and a filler. Using a winding machine having a pair of winding shafts, each winding shaft having at least two winding portions with different outer diameters, with the tips of the pair of winding shafts in contact with each other. The first winding part in which the middle part of the conducting wire having a flat cross section is brought into contact with the spindle of the winding machine and wound in two stages so that both ends of the conducting wire are located on the outer periphery, and the inner diameter is the first A second winding part wound around the coil winding axis in a direction opposite to each other so that the outer diameter of the winding part is equal to or larger than the outer diameter of the winding part; A step of forming a coil by pulling out the end portion of the coil, and a pair of tabs from both ends of the coil And forming a molded body containing the coil by heating and compressing the coil, the coil, the winding shaft is parallel to the mounting surface of the molded body, and the surface of the lead-out end is the molded body. It is formed so as to be exposed on the surface of the mounting surface.

According to the surface mount inductor manufactured by the present invention, by using the lead end portion of the coil as a terminal, thermal stress and mechanical stress to the coil are reduced, and further, generated between the coil and the external terminal. 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, using a winding machine provided with at least two winding portions each having a different outer diameter on the winding shaft, the second winding portion is coiled so that the inner diameter thereof becomes the outer diameter of the first winding portion. Since the winding is formed by shifting the positions in opposite directions along the winding axis, mechanical stress applied to the conductor can be reduced.
By winding the coil so that the mounting surface of the surface mount inductor and the winding axis direction of the coil are parallel, the shape of the coil can be made symmetrical.
From the above, it is possible to provide a method for manufacturing a surface-mount inductor that reduces thermal stress and mechanical stress on the coil, suppresses the resistance value, and has no polarity of electrical characteristics.

It is a perspective view of the coil used in the Example of the manufacturing method of the surface mount inductor of this invention. It is a figure which shows the winding method of the coil used in the Example of the manufacturing method of the surface mount inductor of this invention. It is a perspective view of the tablet used in the Example of the manufacturing method of the surface mount inductor of this invention. It is a top view of the mounting surface of the tablet used in the Example of the manufacturing method of the surface mount inductor of this invention. It is sectional drawing for demonstrating the Example of the manufacturing method of the surface mount inductor of this invention. It is another sectional view for explaining an example of a manufacturing method of a surface mount inductor of the present invention. It is a perspective view of another coil used in the Example of the manufacturing method of the surface mount inductor of this invention.

  Embodiments of a method for manufacturing a surface mount inductor 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 is an air-core coil having a symmetrical shape formed by winding a flat wire having an insulation coating so that both ends thereof are positioned on the outer periphery. is there. The coil 2 includes a first winding portion 2c wound in two stages so that both ends of the flat wire are positioned on the outer periphery, and a coil having an inner diameter equal to or larger than the outer diameter of the first winding portion 2c. And a second winding part 2d wound in a position opposite to each other along the winding axis, and a lead-out end that is an end of a rectangular wire from the outer periphery of each second winding part 2d 2b is pulled out. 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. 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 of the coil 2 during winding.

A method for winding the coil 2 will be described. The coil 2 is formed by winding a rectangular wire having an insulating coating using a winding machine including a pair of spindles 3 having two winding portions 3a and 3b having different outer diameters.
The pair of spindles 3 has a cylindrical first winding portion 3a and an outer diameter larger than the outer diameter of the first winding portion 3a. A cylindrical second winding portion 3b having a cylindrical shape having an outer diameter larger than the outer diameter of the second winding portion 3b adjacent to the second winding portion 3b with the central axis coinciding with and adjacent to the second winding portion 3b. Each having a wall. The length of each winding portion in the winding axis direction is longer than the length of the width of the rectangular wire used for the coil, and the tip 3c of the spindle 3 is in the direction opposite to the second winding portion 3b. It is an end surface part of the part 3a. As shown in FIG. 2A, the two spindles 3 are arranged so that the tips 3c face each other.

  Next, as shown in FIG. 2B, the wide surface 2a in the middle of the flat wire is brought into contact with the first winding portion 3a, and the outer diameter of the winding is the outer diameter of the second winding portion 3b. The first winding portion 3a is wound in two stages in the winding axis direction so as not to become larger. Thereby, the 1st winding part 2c is formed in the 1st winding part 3a, respectively. Next, both ends of the flat wire are shifted from each other in the opposite direction along the winding axis of the winding portion of the spindle 3 from the first winding portion 3a and wound around the second winding portion 3b. As shown in 2 (c), the second winding portion 2d is formed in the second winding portion 3b. A flat wire is drawn out from the outer periphery of the second winding portion 2b and processed to form a drawing end. 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 (d), the symmetrically shaped coil 2 can be produced by pulling apart the spindles whose tips 3c are in contact with each other.

The molded body 4 will be described. The molded body 4 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.
As shown in FIG. 3, the tablet 4a is a cube having an open end on one side surface, and has a space 4b for accommodating 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, each 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. 5 (b), the other two tablets 4 a are placed 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. Fit together. 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, as shown in FIG. 5C, the lead-out end portion 2b of the coil 2 is exposed to the mounting surface 4e. The two tablets 4a are fixed in an embedded state, and the two tablets 4a are pressed to form a molded body 4 in which the coil 2 is sealed.

Next, a method for processing the leading end portion 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 embedded so that the surface is exposed 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, Sn is sputtered on the lead-out end 2b to form a Sn layer, and then Ni and Cr are simultaneously sputtered at a predetermined ratio to form a Ni—Cu layer. By performing sputtering in this way, the lead end 2b can be processed into the external terminal 5. Since a rectangular wire is used, the fixing strength is higher than that of the round wire, and the terminal flatness is also high.

  In the surface mount inductor 1 manufactured in this way, the shape of the built-in coil 2 is bilaterally symmetric, so that the electrical characteristics are the same regardless of which terminal is used during use, and it has 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.

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. For example, the shape of the tablet of the embodiment is such that the pair of facing sides including the side closest to the opening end is the short side and the other pair of facing sides is the long side, but the short side and the long side are reversed. It may be. The coil may be composed of one layer having the same inner diameter, or may be composed of three or more layers having different inner diameters as shown in FIG.
When the coil is composed of two or more layers having different inner diameters, the first winding part, the second winding part,... Number it. An inner diameter of a winding part (X + 1 winding part) obtained by adding 1 to a certain number X is larger than an outer diameter of a winding part (Xth winding part) with a certain number X. For example, as shown in FIG. 7, the coil 12 composed of three layers having different inner diameters has a larger inner diameter of the second inner winding part than the outer diameter of the first inner winding part. The inner diameter of the third inner winding is larger than the outer diameter of the third inner winding. The outer diameter / inner diameter of the innermost winding part of the coil is the smallest, and the outer diameter / inner diameter becomes larger as the outer winding part is reached.
Each winding part of the coil shown in FIG. 1 has two stages, but is not limited to this, and may be wound in four or more stages.
Further, the second winding portion when there are three winding portions may be inclined obliquely along the winding axis of the coil.

The spindle requires as many winding portions as the number of coil winding portions. When the spindle has a plurality of winding parts having different outer diameters, the winding parts are numbered as a first winding part, a second winding part,... In order from the winding part having the smallest outer diameter. All the winding parts are cylindrical and are adjacent so that the central axes coincide with each other. From the outer diameter of the winding part numbered X (Xth winding part), add 1 to X The outer diameter of the wound portion (X + 1th winding portion) is larger. One winding portion is prepared more than the winding portion of the coil, and the winding portion having the largest outer diameter is not used for winding the coil but is handled as a stopper.
For example, a spindle used for winding a coil having three winding portions with different inner diameters has a cylindrical first winding portion and a central axis adjacent to the first winding portion, A cylindrical second winding portion having an outer diameter larger than the outer diameter of the first winding portion, and a central axis that is adjacent to the second winding portion and is outside the second winding portion. A cylindrical third winding portion having an outer diameter larger than the diameter, and a central axis that is adjacent to the third winding portion and has an outer diameter larger than the outer diameter of the third winding portion And a columnar wall portion.
Moreover, you may have multiple 2nd winding parts, respectively.
Further, the shape of the spindle may be different as long as it is symmetrical and does not hinder winding. For example, each winding portion may be inclined obliquely along the winding axis of the coil, or between each winding portion may be inclined obliquely along the winding axis of the coil instead of a step.

DESCRIPTION OF SYMBOLS 1 Surface mount inductor 2, 12 Coil 2a Wide surface 2b Draw-out edge part 2c 1st winding part 2d 2nd winding part 3 Spindle 3a 1st winding part 3b 2nd winding part 3c Tip 4 Molding body 4a Tablet 4b Space 4c Axis 4d Slit 4e Mounting surface 5 External terminal

Claims (3)

In a method for manufacturing a surface mount inductor comprising a coil formed by winding a conductive wire, and a molded body in which the coil is sealed with a sealing material including a resin and a filler,
A winding machine having a pair of winding shafts for winding a conducting wire and provided with at least two winding portions having different outer diameters on each winding shaft is used. The first winding in which the end of the shaft is in contact with the spindle of the winding machine in the middle of a flat conductor with a flat cross section and wound in two stages so that both ends of the conductor are positioned on the outer periphery And a second winding part that is wound by shifting the position in opposite directions along the winding axis of the coil so that the inner diameter thereof is equal to or larger than the outer diameter of the first winding part, Forming a coil as a lead-out end by pulling out the end of the conducting wire from the outer periphery of the second winding part;
A step of fitting a pair of tablets from both ends of the coil, and heating and compressing to form a molded body containing the coil,
The coil is formed in the molded body so that the winding axis is parallel to the mounting surface of the molded body and the surface of the leading end is exposed on the surface of the mounting surface of the molded body. Manufacturing method of surface mount inductor.   The method for manufacturing a surface-mount inductor according to claim 1, wherein the pair of winding shafts of the winding machine has an outer diameter that increases with distance from the tip.   The method for manufacturing a surface-mount inductor according to claim 1, comprising a plurality of the second winding portions.

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