JP2014130879A - Manufacturing method of coil-embedded magnetic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method capable of forming plural coil-embedded magnetic elements at the same time while preventing displacement of winding coils.SOLUTION: The manufacturing method of a coil-embedded magnetic element includes at least: a first step to form a primary molding having plural protrusions the cross sectional area of which gets smaller in a projection direction on the upper face of a plate-like molding which contains a first magnetic material and a first resin; a second step to insert an air core for a winding core to each of the plural protrusions to fix the winding coil to the protrusion; a third step to form a secondary molding containing a second magnetic material and a second resin on the upper face of the primary molding on which the winding coils are fixed to the respective protrusions to form a molded-coil molding in which the winding coil is embedded; a fourth step to separate the molded-coil molding for each of the winding coils to form pieces of the molded-coil molding; and a fifth step to provide a terminal electrode which is electrically connected to a piece of the winding coil.

Description

  The present invention relates to a method for manufacturing a coil-embedded magnetic element in which a coil is embedded in a magnetic material among inductance components such as an inductor, a choke coil, and a transformer.

  With the recent downsizing and higher functionality of electronic devices, there are increasing demands for electronic components that are small, low profile, and have a minimal mounting area. For inductor components, various products and manufacturing methods have been proposed in order to realize these requirements.

  As an example of such an inductor component, a coil embedded type inductance component in which a coil is embedded in a mixture of metal magnetic powder and resin has been proposed. An example of a method for manufacturing such an inductor component is Patent Document 1.

  In Patent Document 1, in a method for manufacturing a wound-integrated mold coil capable of taking a large number of pieces, a molded body is divided into two, and a wound coil is arranged on the upper surface of one molded body. After the portion is melted and the wound coil is embedded under pressure, the other molded body is similarly partially melted to substantially embed the coil, thereby preventing misalignment when the wound coil is disposed. Technology is disclosed.

JP 2011-3761 A

  However, in the manufacturing method of Patent Document 1, a process for melting a part of the molded body is essential, and therefore the number of steps in the manufacturing process increases, leading to an increase in product cost.

  Further, since the winding coil is arranged by embedding the winding coil in the molten compact, the positional deviation of the winding coil particularly in the vertical position becomes a problem.

  In order to solve the above-described problems, a method for manufacturing a coil-embedded magnetic element according to the present invention includes a plurality of protrusions whose cross-sectional area decreases on the upper surface of a plate-like molded body including a first magnetic material and a first resin. A first step of producing a primary molded body having a portion; and a second step of inserting an air core of a winding coil into each of the plurality of convex portions and fixing the winding coil to the convex portion. And a secondary molded body including a second magnetic material and a second resin is provided on the upper surface of the primary molded body having the winding coil fixed to the convex portion, and the wound coil is embedded. A third step of producing a molded coil molded body, a fourth step of separating the molded coil molded body for each of the winding coils into individual pieces, and an electrical connection between the wound coil and the individual pieces. A fifth step of providing a terminal electrode to be connected to It provided even without.

  According to the present invention, a coil-embedded magnetic element can be efficiently manufactured by separating a molded coil molded body in which a plurality of wound coils are embedded in a molded body for each coil. Since the positional deviation at the time of arranging the winding coil can be solved by a simple method, a coil-embedded magnetic element with few defects and excellent magnetic characteristics can be realized.

The perspective view of the coil embedding type | mold magnetic element in one Example of this invention Sectional drawing of the coil-embedded magnetic element in one Example of this invention The schematic diagram which shows the manufacturing process of the coil embedding type magnetic element in one Example of this invention. The top view and side view of the primary molded object after the winding coil mounting process in one Example of this invention The side view of the primary molded object after the winding coil mounting process in one Example of this invention

  Hereinafter, the coil-embedded magnetic element 4 according to the present invention will be described.

  FIG. 1 is a perspective view of a coil-embedded magnetic element 4 according to the present invention, and FIG. 2 is a sectional view thereof.

  The coil-embedded magnetic element 4 of the present invention includes a composite magnetic material 1 containing magnetic powder and resin, a wound coil 3 embedded in the composite magnetic material 1, and a terminal that is electrically connected to the wound coil 3. And at least an electrode 2.

  Magnetic materials used for the coil-embedded magnetic element 4 of the present invention include crystalline materials such as Fe, Fe—Si—Cr, Fe—Si—Al, Fe—Si, Fe—Ni, or non-crystalline materials. Fe-Si-Cr-B system, Fe-Si-NB-B system, nano-crystalline alloy, Fe- (Al, Ga) -PCB system, Fe- (Zr) , Hf, NB, Ta) -B-based, Fe-Co-Ln-B-based metallic glass, or the like can be used. These magnetic materials can be used in combination of one kind or two or more kinds of magnetic materials. Among the above magnetic materials, Fe-based metal magnetic powder has a high saturation magnetic flux density, and thus is useful for use at a large current.

  When the Fe-Si-Cr system is used among the crystalline materials, the Si ratio is 1 wt% or more and 8 wt% or less, the Cr ratio is 2 wt% or more and 8 wt% or less, and the rest is Fe and It is desirable to consist of inevitable impurities. Examples of inevitable impurities include Mn, Cr, Ni, P, S, and C.

  Inclusion of Si has the effect of reducing magnetic anisotropy and magnetostriction constant, increasing electric resistance, and reducing eddy current loss. When the content is 1% by weight or more, an effect of improving soft magnetic characteristics can be obtained, and when the content is 8% by weight or less, a decrease in saturation magnetization can be suppressed and a decrease in DC superimposition characteristics can be suppressed.

  Moreover, there exists an effect which improves a weather resistance by containing Cr. By making it 2% by weight or more, it is possible to obtain a weather resistance improving effect, and by making it 8% by weight or less, it is possible to suppress the deterioration of soft magnetic properties.

  In the case of using an Fe-based metal magnetic powder, it is desirable that it consists of Fe as a main component element and inevitable impurities. Examples of inevitable impurities include Mn, Cr, Ni, P, S, and C. A high saturation magnetic flux density can be obtained by increasing the purity of Fe.

  When Fe-Si-Al-based metal magnetic powder is used, the ratio is as follows: Si is 8 wt% or more and 12 wt% or less, Al content is 4 wt% or more and 6 wt% or less, and the balance is Fe and It is desirable to consist of inevitable impurities. Examples of inevitable impurities include Mn, Cr, Ni, P, S, and C. This is because high magnetic permeability and low coercive force can be obtained by setting the content of each constituent element within the above composition range.

  In the case of using an Fe—Si based metal magnetic powder, it is desirable that Si is 1% by weight or more and 8% by weight or less, with the balance being Fe and inevitable impurities. Examples of inevitable impurities include Mn, Cr, Ni, P, S, and C. Inclusion of Si has the effect of reducing magnetic anisotropy and magnetostriction constant, increasing electric resistance, and reducing eddy current loss. When the content is 1% by weight or more, an effect of improving soft magnetic characteristics can be obtained, and when the content is 8% by weight or less, a decrease in saturation magnetization can be suppressed and a decrease in DC superimposition characteristics can be suppressed.

  In the case of using Fe—Ni-based metal magnetic powder, the ratio is preferably such that the Ni content is 40% by weight or more and 90% by weight or less, and the remainder is made of Fe and inevitable impurities. Examples of inevitable impurities include Mn, Cr, Ni, P, S, and C. The role of Ni in the present invention is that when the Ni content is less than 40% by weight, the effect of improving the soft magnetic properties is poor, and when it is more than 90% by weight, the saturation magnetization is greatly reduced and the DC superposition characteristics are deteriorated. Further, it is possible to contain 1 to 6% by weight of Mo in order to improve the magnetic permeability.

  The average particle size of the metal magnetic powder used in the coil-embedded magnetic element 4 of the present invention is preferably 1 to 100 μm. By setting the average particle diameter to 1.0 μm or more, a high filling rate can be obtained, and a decrease in magnetic permeability can be suppressed. Further, by setting the average particle diameter to 100 μm or less, it is possible to suppress an increase in eddy current loss in the high frequency region. More preferably, it is the range of 5-30 micrometers.

  Examples of the resin used for the coil-embedded magnetic element 4 of the present invention include a thermosetting resin and a thermoplastic resin. In addition, in the composite magnetic material 1 that is a mixture of a magnetic material and a resin, when a metal magnetic powder is used, a small amount of a coupling agent may be added as an additive in consideration of the adhesion between the metal magnetic powder and the resin. . In addition, in the composite magnetic material 1, a small amount of release agent is used for the purpose of improving the fluidity when melted by applying heat at the time of molding, and for providing the mold material and mold release properties. It may be added.

  When a thermosetting resin is used for the coil-embedded magnetic element 4 of the present invention, for example, an epoxy resin, a phenol resin, an unsaturated polyester resin, a silicone resin, and the like can be given.

  When an epoxy resin is used as the thermosetting resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, Naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin and the like can be mentioned. These resins may be used alone or in combination of two or more materials.

  As a thermosetting resin, as a hardening | curing agent required when using an epoxy resin, a novolak-type phenol resin, a dicyandiamide, an acid anhydride etc. can be mentioned, for example. One of these may be used alone, or two or more materials may be used in combination. Examples of the curing catalyst required when using an epoxy resin as the thermosetting resin include imidazoles such as 2-methylimidazole and 2-phenylimidazole, organic phosphines such as triphenylphosphine, tributylphosphine, and trimethylphosphine, Tertiary amines such as triethanolamine and benzylmethylamine can be used.

  When a thermoplastic resin is used for the coil-embedded magnetic element 4 of the present invention, polyphenylene sulfide resin, polyamide resin, polyester resin, polypropylene resin, liquid crystal polymer and the like can be mentioned.

  Examples of the coupling agent used for the coil-embedded magnetic element 4 of the present invention include a silane coupling agent or a titanate coupling agent.

  Examples of the mold release agent used in the coil-embedded magnetic element 4 of the present invention include carnauba wax and carboxyl group-containing polyolefin, which are substances composed of higher fatty acids or fatty acid esters or fatty acid amides thereof. One of these may be used alone, or two or more materials may be used in combination. This higher fatty acid is a saturated fatty acid having 12 or more carbon atoms or an unsaturated fatty acid. Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, salaric acid, behenic acid, lignoceric acid, and montanic acid. As unsaturated fatty acids, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, oleic acid, elaidic acid, erucic acid, nervonic acid, etc. Can be mentioned.

  Below, the manufacturing method of the coil embedding type | mold magnetic element 4 of this invention demonstrates the case where a metal magnetic powder is used as magnetic powder, and a thermosetting resin is used as resin.

  As the thermosetting resin, a resin that is solid at around room temperature, reaches a softening point temperature by heating, melts, and further heats by causing a crosslinking reaction by heating.

  First, the magnetic metal powder and thermosetting resin are mixed uniformly using a mixer or blender, and the kneader, planetary mixer, and mixing are applied while applying a temperature higher than the softening point of the thermosetting resin. A kneaded product is obtained by melt-kneading using a roll or the like.

  Here, the thermosetting resin needs to be melted at a temperature at which a crosslinking reaction (thermosetting) does not occur in consideration of a subsequent curing step.

  Examples of the molding method of the primary molded body 5 and the secondary molded body 6 formed of the metal magnetic powder and the thermosetting resin by molding the kneaded product include granulated powders such as injection molding, transfer molding, and compression molding. There are two methods, plastic molding method in which resin components are heated and melted and injected into the mold, or powder molding method in which granulated powder is directly supplied to the mold and pressed. May be.

  FIG. 3 is a schematic diagram of the manufacturing process showing from the molding process to the separation process of the molded coil molded body 9 in the method for manufacturing the coil-embedded magnetic element 4 of the present invention.

  Hereinafter, the molding of the primary molded body 5 and the secondary molded body 6 will be described in detail by taking an injection molding method as an example.

  First, the process from the forming process of the primary molded body 5 to the mounting process of the wound coil 3 will be described with reference to FIGS. When the primary molded body 5 is injection-molded (as is the secondary molded body 6) as shown in FIG. 3 (a), a kneaded product composed of a thermosetting resin in a molten state higher than the softening point temperature and a metal magnetic powder is used. The thermosetting resin is cured by injecting and filling the mold and applying heat to the resin component inside the mold. Here, the thermosetting resin is not completely cross-linked, and remains in a semi-cured state, thereby improving the adhesion with the secondary molded body 6 and increasing the mechanical strength of the coil-embedded magnetic element 4. Can do.

  Moreover, the filling rate of the metal magnetic powder can be increased by applying pressure to the cured primary molded body 5 in the mold for a certain period of time.

  In addition, since the molding method of the primary molded body 5 is a compacting method, it can be pressure-molded at a high pressure, so the filling rate of the metal magnetic powder can be increased compared to the plastic molding method, and a high ratio. Magnetic permeability can be obtained.

  Next, the convex part 7 formed on the upper surface of the primary molded body 5 will be described in detail.

  As shown in FIG. 3 (b), a convex portion 7 is formed on the upper surface of the primary molded body 5, and the shape of the convex portion 7 is changed to a shape in which the cross-sectional area becomes smaller in accordance with the convex direction. In the mounting step, it is possible to easily fit the air core portion of the winding coil 3 into the convex portion 7. This is effective when the second molded body is formed by a plastic molding method in a later step, and can prevent displacement of the winding coil 3 caused by the pressure for injecting the kneaded material.

  In addition, the cross-sectional area refers to a cross section in a plane parallel to the planar direction of the primary molded body 5.

  Further, as shown in FIGS. 4A and 4B, it is necessary to fix the lead-out position of the winding coil 3 in advance in consideration of the connection between the winding coil 3 and the terminal electrode 2 electrically connected. In some cases, it is more effective, and it is possible to prevent the displacement of the winding coil 3 that occurs when the winding coil 3 rotates around the convex portion 7.

  Further, by making the cross-sectional shape of the convex portion 7 the same as the air core shape of the winding coil 3, it becomes easier to mount the winding coil 3, and to suppress the positional variation of the plurality of winding coils 3. it can. For example, for the winding coil 3 having a substantially circular air core shape, it is preferable that the cross section is a convex portion 7 having a substantially circular shape.

  Further, as described above, the cross-sectional shape of the convex portion 7 and the air-core shape of the winding coil 3 are the same, and the cross-sectional area at the tip of the convex portion 7 is S, and the cross-sectional area at the end of the convex portion 7 is P. When the winding coil 3 is disposed on the primary molded body 5 by satisfying the relationship of S <D ≦ P when the area of the air core is D, winding is performed at a certain height of the convex portion 7. Since the coil 3 is fixed, it is possible to prevent the vertical position variation among the plurality of winding coils 3.

  Although D = P is satisfied, the diameter of the air core of the winding coil 3 may vary even if there is a variation in the diameter of the air core of the winding coil 3 and the diameter of the end of the projection 7. On the other hand, if the diameter of the end of the convex portion 7 is within 10%, the magnetic characteristics are not affected in product design.

  Moreover, as shown in FIG. 5, the winding coil 3 can be more easily inserted into the convex portion 7 by making the tip portion of the convex portion 7 a curved surface.

  As described above, by forming the convex portion 7, the winding coil 3 can be easily arranged and fixed.

  Next, as shown in FIG.3 (c), the formation process of the secondary molded object 6 is demonstrated. The molding of the secondary molded body 6 is carried out in the same manner as the molding process of the primary molded body 5 described above, and a kneaded material made of a metal magnetic powder and a molten thermosetting resin is filled in the mold and thermoset in the mold. As a result, the primary molded body 5 and the secondary molded body 6 are integrated into the composite magnetic material 1, and a molded coil molded body 9 in which a plurality of wound coils 3 are embedded is produced.

  In addition, when manufacturing the coil embedded type magnetic element 4 of 2016 size or less, since it is necessary to fill a narrow space between the primary molded body 5 and the coil with a magnetic material, for example, injection molding, transfer molding, compression molding, etc. It is preferable that molding is performed by a plastic molding method in which a resin component of a mixture of a magnetic material and a resin is heated and melted to perform molding so that the magnetic material can easily enter the narrow space.

  In addition, although Fig.4 (a) has taken out the drawing position used as the pair of the winding coil 3 in the respectively opposite direction, this drawing position is not specifically limited, It can also draw out from a side surface or an upper surface.

  Next, as shown in FIG. 3 (d), the molded coil molded body 9 is removed from the mold and divided into pieces with a predetermined dimension for each coil to obtain individual pieces 8. Examples of the dividing method include a dicing method, a braking method after forming the dividing groove, and a cutting method using a laser. About the said division | segmentation groove | channel, you may shape | mold so that a groove | channel may enter into the molded coil molded object 9 with a metal mold | die shape.

  Next, the terminal electrode 2 is formed on the divided pieces 8 so as to be electrically connected to the winding coil 3. As a method for forming the terminal electrode 2, for example, a method of performing nickel-tin plating after applying a conductive adhesive can be cited. However, as long as conduction with the winding coil 3 can be ensured, other methods are used. You may do it.

  According to the present invention, it is possible to manufacture a highly reliable coil-embedded magnetic element that is small and excellent in mass productivity.

DESCRIPTION OF SYMBOLS 1 Composite magnetic material 2 Terminal electrode 3 Winding coil 4 Coil embedding type | mold magnetic element 5 Primary molded object 6 Secondary molded object 7 Convex part 8 Piece 9 Mold coil molded object

Claims (4)

A first step of producing a primary molded body having a plurality of convex portions whose cross-sectional area is reduced along the convex direction on the upper surface of the plate-shaped molded body including the first magnetic material and the first resin;
A second step of inserting an air core of a winding coil into each of the plurality of convex portions and fixing the winding coil to the convex portion;
A molded coil in which a secondary molded body including a second magnetic material and a second resin is provided on an upper surface of the primary molded body in which the wound coil is fixed to the convex portion, and the wound coil is embedded. A third step of producing a molded body;
A fourth step in which the molded coil molded body is separated for each of the winding coils to form individual pieces;
And a fifth step of providing a terminal electrode electrically connected to the wound coil on the individual piece. The method for manufacturing a coil-embedded magnetic element according to claim 1, wherein a cross section of the convex portion and a shape of the air core of the wound coil are substantially circular. The coil embedding according to claim 2, wherein S <D ≦ P is satisfied, where S is a cross-sectional area at the tip of the convex portion, P is a cross-sectional area at the end of the convex portion, and D is an area of the air core. Method for manufacturing a mold magnetic element. The method for manufacturing a coil-embedded magnetic element according to claim 1, wherein a tip of the convex portion is a curved surface.

Images