JP6332159B2 - Surface mount inductor and manufacturing method thereof - Google Patents

Description

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

  2. Description of the Related Art Conventionally, surface mount inductors in which a coil is incorporated in a body having magnetic powder have been widely used. For example, Patent Document 1 discloses a method of manufacturing a surface-mount inductor that processes a lead end portion of a coil as an external terminal. This method obtains an element body by sealing a coil formed by winding a conducting wire having a rectangular cross section (hereinafter referred to as a flat wire) with a sealing material having magnetic powder.

JP 2004-193215 A

  Since the surface-mount inductor of Patent Document 1 seals the coil with a sealing material having magnetic powder, there is a problem in that the magnetic powder enters between the conductors constituting the coil and the electrical breakdown voltage is reduced.

  Accordingly, an object of the present invention is to provide a surface-mount inductor having a high electrical breakdown voltage while using magnetic powder, and a method for manufacturing the same.

  A surface-mount inductor according to the present invention includes a coil including a winding portion and a lead-out end portion, an insulator including the coil, and an element body including the insulator and containing magnetic powder. In the inductor, the insulator seals the winding part.

  According to the surface mount inductor and the manufacturing method thereof of the present invention, since magnetic powder does not enter between the conducting wires constituting the coil, the electrical withstand voltage does not decrease.

It is a perspective view of the coil used in Example 1 of the present invention. It is a perspective view of the magnetic body core used in Example 1 of this invention. It is a perspective view of the tablet used in Example 1 of the present invention. It is a top view of the mounting surface of the tablet used in Example 1 of the present invention. It is AA sectional drawing for demonstrating the process of inserting a magnetic body core in the coil of the surface mount inductor of Example 1 of this invention. It is AA sectional drawing for demonstrating the process of sealing a coil and a magnetic body core with an insulator of the surface mount inductor of Example 1 of this invention. It is AA sectional drawing for demonstrating the process of sealing an insulator with a tablet of the surface mount inductor of Example 1 of this invention. It is AA sectional drawing for demonstrating the process of compressing and heating a tablet of the surface mount inductor of Example 1 of this invention, and forming an element | base_body. It is a top view of the mounting surface of an element | base_body for demonstrating the process of forming the external terminal of the surface mount inductor of the 1st Example of this invention. It is the perspective view which looked at the surface mount inductor of Example 1 of this invention from the mounting surface side. It is AA sectional drawing for demonstrating the process of sealing a coil and a magnetic body core with an insulator of the surface mount inductor of Example 2 of this invention. It is AA sectional drawing for demonstrating the process of sealing an insulator with a tablet of the surface mount inductor of Example 2 of this invention. It is AA sectional drawing for demonstrating the process of compressing and heating a tablet of the surface mount inductor of Example 2 of this invention, and forming an element | base_body. It is the perspective view which looked at the surface mount inductor of Example 2 of this invention from the mounting surface side.

  Hereinafter, a first embodiment of a surface mount inductor and a manufacturing method thereof according to the present invention will be described with reference to FIGS.

  The coil used in Example 1 will be described. As shown in FIG. 1, the coil 2 is a left-right symmetrical air core coil formed by winding a rectangular wire having an insulating coating so that both ends thereof are positioned on the outer periphery. The coil 2 is wound with the first winding part 2a wound in two steps so that both ends of the flat wire are positioned on the outer periphery, and shifted in opposite directions along the winding axis of the coil 2. A second winding part 2b, and a leading end 2c is drawn from the outer periphery of each second winding part 2b. The lead-out end portions 2c are each drawn perpendicularly 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 of the flat wire, no mechanical stress is applied to the flat wire.

  The magnetic core used in Example 1 will be described. As shown in FIG. 2, the magnetic core 3 has a shape in which the bottom surfaces of two cylinders having different diameters are concentrically connected. When manufacturing the surface mount inductor, the magnetic core 3 is inserted into the air core portion of the coil 2.

The element body used in Example 1 will be described. The element body 4 is formed by combining two tablets 4a as shown in FIG. The tablet 4a is formed from a sealing material including a filler having magnetic powder and an epoxy resin.
The tablet 4a is a cube having an open end on one side surface, and has a space for storing the coil 2 therein. The upper surface and the bottom surface of the tablet 4a have the same shape, and are processed into a mounting surface through a manufacturing process. As shown in FIG. 4, the outer shape of the mounting surface is a rectangle. Of the four sides constituting this rectangle, the side closest to the opening end is the short side, and the side adjacent to the short side is the long side. The mounting surface includes protrusions 4c that protrude perpendicularly to the mounting surface at both ends in the short-side direction, and includes elongated slits 4b at positions adjacent to the protrusions 4c. The leading end 2c of the coil 2 is pulled out from the slit 4b.

  A method for manufacturing a surface-mount inductor will be described with reference to FIGS. 5 to 8 are AA cross-sectional views for explaining the manufacturing method, and FIG. 9 is a plan view of the mounting surface of the element body.

  As shown in FIG. 5A, the magnetic cores 3 are inserted from both sides of the winding axis of the coil 2, respectively. As shown in FIG. 5B, a gap is provided between the magnetic core 3 and the coil 2.

  Next, a mold for forming the insulator is prepared. As shown in FIG. 6A, the mold 6a is a cube having an open end on one surface, and has a space for accommodating the coil 2 and the magnetic core 3 therein. The coil 2 in which two magnetic cores 3 are inserted is placed in the mold 6a. The leading end of the coil 2 is pulled out from the coil 2 in a direction toward the opening end of the mold 6a. As shown in FIG. 6B, an insulating resin is injected. The insulating resin seals the magnetic core 3 and the coil 2. The insulating resin enters a gap provided between the magnetic core 3 and the coil 2. In this state, the insulator 5 containing the coil 2 and the magnetic core 3 can be obtained by degassing the insulating resin. Since the insulator 5 seals the coil 2 with respect to the magnetic core 3, the coil 2 and the magnetic core 3 are not in contact with each other.

  The insulator 5 is taken out from the mold 6a, and as shown in FIG. 7A, the tablets 4a are arranged on both sides of the insulator 5 so that the open ends face each other. As shown in FIG. 7B, each tablet 4a is moved so that the two tablets 4a contain the insulator 5 in which the coil 2 and the magnetic core 3 are sealed. Thereafter, the drawer end 2c of the coil 2 is pulled out from one slit 4b of the tablet 4a. The drawer end 2c extends to the mounting surface of the tablet 4a and is put into the other slit 4b.

  Next, a mold for forming the element body is prepared. As shown in FIG. 8 (a), the mold 6b is a cube having an open end on one surface, and accommodates the coil 2, the magnetic core 3, the tablet 4a, and the insulator 5 therein. Has a space. A tablet 4a in which the coil 2, the magnetic core 3 and the insulator 5 are incorporated is placed in the mold 6b. The leading end of the coil 2 is pulled out from the coil 2 in a direction toward the opening end of the mold 6b. Thereafter, the lid 6c is placed over the opening surface of the mold 6b. Next, as shown in FIG. 8B, by heating and compressing the two tablets 4a, the element body 4 including the coil 2, the magnetic core 3, and the insulator 5 can be obtained. The drawer end 2c is fixed in an embedded state so as to be exposed on the surface of the mounting surface.

Next, a method for processing the leading end 2c into an external terminal will be described.
The leading end 2c exposed / extended on the mounting surface of the element body 4 is irradiated with laser to peel off the insulating coating. Since a flat wire is used, it is easy to set conditions for laser peeling. Next, Ni and Cr are simultaneously sputtered on the lead-out end 2c at a predetermined ratio to form a Ni-Cu layer, and then Sn is sputtered to form a Sn layer, as shown in FIG. The external terminal 7 can be formed.
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 further attached as necessary to serve as an external terminal.

  From the above, a surface mount inductor can be manufactured. As shown in FIG. 10, the surface-mount inductor 1 is sealed with the tablet 4a because the first winding portion 2a and the second winding portion 2b of the coil are hermetically covered with the insulator 5 and covered. At this time, the magnetic powder does not enter between the conductive wires constituting the coil 2, and the electrical withstand voltage does not decrease.

In the surface mount inductor of Example 1, since the coil winding portion was hermetically covered with an insulator with respect to the magnetic core, a magnetic core made of the same material as the tablet or a conductive magnetic core was used. Even in this case, the electrical breakdown voltage does not decrease.
Moreover, since the shape of the built-in coil is bilaterally symmetric and the distance from the drawing position of each drawing end to the external terminal is the same, it has no polarity. A surface mount inductor having no polarity has the same electrical characteristics regardless of whether it is input from any external terminal at the time of use, and therefore there is no need to print markings indicating polarity. Since there is no need to print markings, manufacturing costs can be reduced.

  Hereinafter, a second embodiment of the surface mount inductor and the manufacturing method thereof according to the present invention will be described with reference to FIGS. When using the same thing as Example 1, the same number as Example 1 is attached.

  As shown in FIG. 11, a mold 6a for forming an insulator is prepared. The coil 2 incorporating the magnetic core 3 is placed in the mold 6a. The leading end of the coil 2 is pulled out from the coil 2 in a direction toward the opening end of the mold 6a. As shown in FIG. 11B, the insulator 5 is injected, and the coil 2 and the magnetic core 3 are sealed. At this time, the insulating resin does not enter between the magnetic core 3 and the coil 2. Thereafter, the insulator 5 containing the coil 2 and the magnetic core 3 can be formed by degassing the insulating resin. Since the insulator 5 does not seal the coil 2 with respect to the magnetic core 3, the inside of the coil 2 and the magnetic core 3 are in contact with each other.

  The insulator 5 is taken out from the mold 6a, and as shown in FIG. 12A, the tablets 4a are arranged on both sides of the insulator 5 so that the open ends face each other. As shown in FIG. 12B, each tablet 4a is moved such that the two tablets 4a contain the insulator 5 in which the coil 2 and the magnetic core 3 are sealed. Thereafter, the drawer end 2c of the coil 2 is pulled out from one slit 4b of the tablet 4a. The drawer end 2c extends to the mounting surface of the tablet 4a and is put into the other slit 4b.

  As shown in FIG. 13A, a mold 6b for forming an element body is prepared, and two tablets 4a incorporating the coil 2 and the magnetic core 3 are inserted. The leading end of the coil 2 is pulled out from the coil 2 in a direction toward the opening end of the mold 6b. Thereafter, the lid 6c is placed over the opening surface of the mold 6b. Next, as shown in FIG. 13B, the element body 4 including the coil 2, the magnetic core 3, and the insulator 5 can be obtained by heating and compressing the two tablets 4 a. The drawer end 2c is fixed in a state of being embedded such that the surface thereof is exposed on the surface of the mounting surface.

  Thereafter, similarly to the first embodiment, the surface-mount inductor can be manufactured by processing the lead-out end portion 2 c into the external terminal 7. As shown in FIG. 14, in the surface mount inductor 11, the first winding portion 2a and the second winding portion 2b of the coil are hermetically sealed with the insulator 5, so that the magnetic wire is formed between the conductors constituting the coil. Powder does not enter and electrical withstand voltage does not decrease.

  In the surface mount inductor according to the second embodiment, the core is inserted into the air-core coil, but the coil may be formed by winding a conductive wire directly around the magnetic core. Since the distance between the coil and the magnetic core is short, a surface mount inductor having a high inductance value can be manufactured.

  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. The material of the magnetic core may be ferrite or may contain magnetic powder. 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. Moreover, it is not necessary to use a magnetic core. The conductor wire forming the coil is a rectangular wire, but it may be a round wire or a wire having another cross-sectional shape. The lead end of the coil is used as an external electrode, but a conductor electrically connected to both ends of the coil may be used instead of the external electrode.

DESCRIPTION OF SYMBOLS 1, 11 Surface mount inductor 2 Coil 2a 1st winding part 2b 2nd winding part 2c Lead end part 3 Magnetic body 4 Element body 4a Tablet 4b Slit 4c Projection part 5 Insulators 6a, 6b Mold 6c Lid 7 External electrode

Claims (10)

A coil composed of a winding part and a lead-out end part, a magnetic core, an insulator containing the winding part of the coil and the magnetic core, and an element body containing the insulator and containing magnetic powder; In surface mount inductors with
It has external terminals that extend on the mounting surface and are electrically connected to both ends of the coil.
The element body is a compression molded body of a sealing material containing magnetic powder and resin,
The surface mount inductor, wherein the insulator seals the magnetic core and the winding portion.   The surface mount inductor according to claim 1, wherein the insulator covers the winding portion so that the magnetic core and the coil do not contact each other.   The winding terminal of the coil 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 to constitute the external terminal. Alternatively, the surface mount inductor according to claim 2.   The surface-mount inductor according to claim 1, wherein the external terminal is made of a conductor electrically connected to the lead-out end portion.   The coil is shifted in a direction opposite to each other along the winding axis of the first winding part wound in two stages so that both ends of a rectangular wire having an insulating coating are positioned on the outer periphery. The surface mount inductor according to any one of claims 1 to 4, further comprising a wound second wound portion. A method for manufacturing a surface-mount inductor comprising: a coil composed of a winding part and a lead-out end part; an insulator including the winding part of the coil; and an element including the insulator and including magnetic powder. In
Forming the coil;
Sealing the coil winding with the insulator;
A step of forming the element body by compressing and molding a sealing material that includes magnetic powder and a resin so as to incorporate the insulator in the element body and that surrounds the insulator; and
A method for manufacturing a surface mount inductor, comprising: A surface provided with a coil composed of a winding part and a lead-out end part, a magnetic core, an insulator containing the winding part of the coil, and an element body containing the insulator and containing magnetic powder In the manufacturing method of the mounted inductor,
Forming the coil;
Sealing the winding portion of the coil and the magnetic core with the insulator;
A step of forming the element body by compressing and molding a sealing material that includes magnetic powder and a resin so as to incorporate the insulator in the element body and that surrounds the insulator; and
A method for manufacturing a surface mount inductor, comprising: In the step of sealing the coil and the magnetic core with the insulator,
The method of manufacturing a surface mount inductor according to claim 7, wherein the insulator covers the coil so that the magnetic core and the coil do not contact each other.   9. The method according to claim 6, further comprising a step of forming an external terminal on the mounting surface such that a surface of the lead-out end portion extends to a surface of the mounting surface of the element body. A method for manufacturing the surface mount inductor according to claim 1. Further comprising: a step of forming an external terminal on the mounting surface of the conductor to be connected before and electrically end out come Ki引, according to claim 6 of claim 8 Manufacturing method of surface mount inductor.

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