JP4908640B1 - Molded coil manufacturing method - Google Patents

Abstract

The mold structure is not complicated, the molding process can be simplified, the winding mold position and dimensional variation are small, and the characteristics and reliability are high at low cost, especially in surface mount parts that are strict in the thickness direction. It aims at providing the manufacturing method of a mold coil.
[Solution]
The method for producing a molded coil according to the present invention is a method for producing a molded coil in which a coil is sealed with a mold resin obtained by kneading a resin and a magnetic powder using a plastic compression molding method. After embedding in the molten mold material, fluid pressure is applied from a surface direction different from the embedding direction, so that the embedding position is easily fixed, the thickness in the embedding direction is defined by a mold, and a precise thickness shape is obtained. A coil-integrated mold coil is manufactured.
[Selection] Figure 3

Description

  The present invention relates to a method for manufacturing a molded coil using a plastic compression molding method.

  Conventionally, a molded coil in which a coil is wound around a core such as a ferrite core and sealed with a magnetic molding material has been widely used. Conventional mold coil molding methods are performed using transfer molding (transfer molding) or injection molding (injection molding).

  Conventional molding materials using transfer molding and injection molding have not been able to produce a material with sufficiently high relative permeability while maintaining fluidity, so there are a lot of monolithic molding coils that do not use a magnetic material as a core to obtain inductance. The number of windings is required and the DC resistance becomes very high, and the winding volume tends to increase, so the cross-sectional area of the magnetic material is limited and the DC superimposition characteristics are also very low, which satisfies the characteristics as a power inductor I couldn't.

On the other hand, an inductor in which a granulated powder such as a binder, a magnetic powder, and a winding are integrated by powder compression molding is disclosed (for example, see Patent Document 1). Furthermore, a metal iron-based magnetic power inductor using this method has been highly evaluated.

  However, since the powder compaction method integrates the powder by pressurization, a large pressure is required, which causes a large damage to the wound winding. Further, since the volume of the filled powder is greatly changed by compression, a variation in molding density or the like occurs depending on the presence or absence of an internal winding. Usually, in order to alleviate this, the volume of the portion without winding is more than necessary on the magnetic circuit.

  Therefore, the applicant proposed in Japanese Patent Application No. 2008-4005 filed earlier that a winding method is embedded with high accuracy by a plastic molding method, a material loss is small, and a low-cost production method for a high-performance molded coil is proposed.

Further, the applicant Japanese Open 2009-267350 has filed previously, without separating the feed material, can be further embedded winding with high precision, less material loss method forming a low-cost high-performance molded coil Proposed.

JP 2007-49073 A Japanese Patent Application No. 2008-4005 JP 2009-267350 A

  In Japanese Patent Application No. 2008-4005 filed earlier, the method for defining the winding position is a mold, so that the mold is complicated, and in the case of supplying powder-type material, it is easy for air bubbles to be entrained inside the molded body. It was.

Further, in JP-open 2009-267350 filed previously, a winding method for producing an integrated molded coil using a plastic compression molding, Figure 1 compares cavity 1 and the sliding punch, slidable alone respectively A method in which the mold resin is formed in stages after holding the winding at the position specified by the positioning pin 2 and the support pin 3 using a mold constituted by the positioning pin 2 and the support pin 3. It is.

The mold resin is pressurized in several stages, and usually after one stage of pressurization, the positioning pin 2 is moved to a predetermined position, and the second stage of pressurization is performed. Finally, the support pin 3 is moved to a predetermined position, and the third stage pressurization is performed.

  In this way, the pressurization divided into several degrees complicates the process, which increases the equipment cost and man-hours.Since the support pins and positioning pins slide while in direct contact with the mold resin, the pins and guides wear. There is a severe problem with mold life.

In addition, since resin and kneaded material flow into and adhere to the gap between each pin and the pin guide, man-hours are required for the peeling process, cleaning and removal of foreign matter, etc., and the mold structure becomes large due to mold wear and backlash. Therefore, it is necessary to use a high-hardness material with little wear and the cost is high.

Furthermore, in the conventional method, the compression direction is the thickness direction, and the end point of the compression direction is determined at the point where the pressure is applied, so the thickness varies depending on the amount of material input, and the surface mount part has strict specifications in the thickness direction. Then it was easy for defects to occur.

In addition, since the conventional method is pressurization on the entire surface of the molded body, it is disadvantageous in terms of cost because measures such as cutting the entire surface are required for a defective size.

In a method of manufacturing a mold coil in which an air core coil is sealed with a magnetic mold resin in which a resin and a magnetic powder are kneaded, a step of embedding at least a part of the air core coil in a molten mold material, and an embedding direction An object of the present invention is to manufacture an integral mold coil that is molded by flowing and pressurizing mold resin in a cavity from a different direction.

A mold coil manufacturing method, wherein a gap 5 through which a large amount of resin is selectively discharged is intentionally provided in a mold.

A method for producing a mold coil, characterized in that burrs are punched out by a punch 15 attached to a molding die and a suitable die jig 18.

  In the method for producing a molded coil according to the present invention, the molding material is supplied in two or more, and the embedding material 7 is smaller than the embedding material cavity 9 in advance by a powder compression molding method or the like, and the shape is approximated. After the burying material 7 is melted, the burying position is defined by burying the air-core coil 10. Next, by completely molding the air-core coil by flow pressurization of mold resin from a direction different from the embedding direction, the thickness in the embedding direction can be determined at a specified position such as a mold. This is particularly effective for improving the characteristics of surface mount mold coils whose specifications in the thickness direction are strict and for improving the yield rate.

In this manufacturing method, it is possible to control a plurality of pressurizations in one place, and the apparatus, mold cost, and productivity can be improved.

In this manufacturing method, since the pressurization is performed from a part from the prescribed size of the mold coil, an excess portion (in this manufacturing method, by using the punching punch 15 and the punching die jig 18 having an appropriate shape) is used. The burr 16) can be easily removed and the shape defects can be reduced.

FIG. 1 is a perspective view showing a positioning pin support pin structure of a mold used for explaining a conventional construction method. FIG. 2 is a transparent perspective view showing an image for explaining the manufacturing method of the present invention. FIG. 3 is a cross-sectional view for explaining the manufacturing method of the present invention and the first embodiment.

  The method for producing a molded coil according to the present invention is such that the mold material, which is a magnetic material kneaded material composed of magnetic powder and thermosetting resin, is pulverized and then subjected to powder compression molding or the like to form the desired shape of the coil molded body 17. The shape is smaller than the coil molded body 17 and does not become excessive from the upper surface of the embedding pressure when the air core coil 10 is buried under pressure, and the portion other than the air core coil pressure embedding surface enters the embedding material 7. It is preferable to mold the embedded material 7.

This is because the excess material adheres to the embedded jig or the like of the air-core coil 10 and may contaminate the jig, fluctuation of the material amount due to the attachment of the jig, stress on the embedded air-core coil 10, etc. The problem is likely to occur. Moreover, when parts other than a pressure embedding surface are not embed | buried completely, there exists a possibility that a winding position may shift | deviate by the resin flow orthogonal to an embedding direction, or winding itself may deform | transform.

The air core coil 10 is embedded from the winding core direction after the embedded material 7 is melted. By doing so, the embedding material 7 is filled in the winding core portion, and displacement and deformation of the air core coil 10 can be prevented. The melting temperature is determined so that the viscosity is such that there is little stress during embedding and the embedding position can be maintained. In general, when the melting temperature is high, the viscosity decreases and the embedding stress is reduced, but the embedding position is easy to move. Further, when the volume ratio of the magnetic powder is higher than that of the thermosetting resin, the viscosity increases, and the phenomenon reverse to the above occurs.

The air-core coil 10 uses a fused wire so that it will not be deformed by stress during embedment, and in particular, edgewise winding using a rectangular wire and outer and outer windings can be densely wound and are effective in terms of characteristics.

The winding terminal 11 is processed into an appropriate shape, inserted into the gap between the embedded material cavity 9 and the embedded material 7, and then embedded with the air core coil 10 in the embedded material 7, the winding terminal 11 becomes embedded in the embedded material cavity 9. Between the embedded material 7 and the terminal is easily exposed. Further, the side of the buried material cavity on the terminal surface is made movable, the winding terminal is exposed and the air-core coil 10 is buried, and then the movable cavity side surface is moved to move the winding terminal 11 between the cavity side surface and the buried material 7. You may make it easy to expose.

The step of embedding the air-core coil may be once cooled and taken out, and then set again in the mold. In some cases, such as when the mold temperature conditions differ greatly between the embedding temperature and the curing temperature, it may be more efficient to solidify the molten resin and then take it out and set it again in the hot mold as shown in FIG. .

The sealing material 12 may be set so as to cover the embedded surface as shown in FIG. 3 (c ′) sealing material set, or an appropriate amount that enters the female part of the pressure punch 14 is introduced. Also good. When the embedded surface is covered as shown in FIG. 3 (c ′), the amount may be excessive or less than the cavity that is pushed out to the female part of the pressure punch 14 when the upper die is clamped in FIG. 3 (d ′) . good.

The upper die clamping in FIG 3 (d'), the thickness of the coil molded product is defined. Defining the thickness direction of the coil molded body as shown in FIG. 3D 'is effective when the standard of the thickness direction is strict. Since the thickness direction can be determined by the accuracy of the mold, the effective design thickness can be increased, and the characteristic specifications can be increased.

The side surface flow pressurization in FIG. 2 (e) can be shared when the sealing material is connected to an adjacent molded body as shown in FIG. It is necessary to apply pressure. When controlling individually, since an apparatus and a metal mold become complicated, it becomes disadvantageous in cost.

Fig. 2 (e) The mold temperature at the time of side surface flow pressurization is preferably high as long as there is no damage or malfunction so that the resin flows sufficiently and cures quickly.

FIG. 2 (e) Side flow pressurization aims to mold the coil molded body 17 into a prescribed shape, and the mold material containing a large amount of the resin component is discharged from the gap 5 by pressurization, and the volume ratio of the magnetic body is set. Pressurize to raise. When an excessive sealing material 12 is added as shown in FIG. 3 (d ′), it is possible to form an approximate shape by the upper mold clamping shown in FIG. 3 (d ′), but shape defects tend to occur. In addition, it is not possible to improve the characteristics by discharging a material that selectively contains a large amount of resin components.

After heating and curing for a predetermined time, the coil molded body 17 may be taken out and removed with a predetermined cutting tool. However, after removing the upper mold 13 and the pressure punch 14, the die mold 18 is set and the coil molded body is set. It is effective to extrude 17 and remove the burrs 16 because the burrs 16 can be accurately removed at a time. In FIG. 3 (f ′), the punch 15 that has been manufactured in advance is extruded into the mold. The punching die jig may be a separate part from the molding die, but may be crafted into an upper die.

After mixing 8 wt% of epoxy resin mixture of 92 wt% amorphous magnetic powder and novolak type epoxy resin and phenol novolak type resin at 110 degrees 40 minutes in a kneader, add 0.05 wt% of TPP to the epoxy resin mixture. Further, after kneading for 3 minutes, the material was taken out from the kneader and cooled to obtain a plurality of kneaded masses having a diameter of about 8 cm.

The kneaded mass was coarsely pulverized to a particle size of about 2 mm with a crusher mill, finely pulverized with a hammer mill (using a 2 mmφ mesh), and passed through a sieve with an opening of 0.5 mm to obtain the raw material powder.

The mixed powder uses a 2.2 mm * 1.9 mm square die, and about 20 mg of material is powder compression molded to create an embedded material 7, which is similarly sealed at about 5 mm * 2.4 mm * 0.5 mm. Material 12 was made.

The terminal surface of the winding terminal 11 is made by making an air core coil 10 wound in front and outside with a self-bonding rectangular wire having a height of 0.5 mm, a length * width of 2.3 * 1.8 mm and an elliptical winding core. Was bent to about 70 degrees.

Use a middle mold 6 that has a cavity shape (embedded material cavity 9) of 2.5 mm * 2.0 mm * 0.9 mm, and mold a gap of 540 μm on the surface that extends perpendicularly from all sides of the cavity to the lower mold. Formed with. The mold assembled in the state of FIG. 3 (a ′) was preheated to 100 ° C., and the embedding material 7 was set so as to be positioned substantially at the center of the middle mold 6 cavity.

    After the embedded material was melted, the air-core coil 10 was set. The winding terminal 11 was inserted from a slight angle so as to enter the gap between the embedded material 7 and the embedded material cavity, and finally pressed to a predetermined position so as to be perpendicular to the mold surface.

The embedded material 12 was placed in the embedded material cavity 9 having a size of 7 mm * 2.5 mm * 0.3 mm so that the embedded material 12 substantially entered the center. The mold temperature was raised to 150 degrees, and the upper die 13 pressed and fixed as in FIG. 3 (d').

The pressure punch 14 preheated to 150 ° C. was set, pressurized with 30 kg for 5 minutes, and held for 5 minutes with the load applied to cure the resin.

After removing the upper die 13 and the pressure punch 14, set the punching die jig 18 with a 2.5mm * 2.0mm square window as well as the shape of the buried cavity, and then slide the punching punch 15 after fixing. Thus, the burr 16 and the coil molded body 17 were separated, and the coil molded body 17 was obtained.

After removing the coating of the winding terminal 11 with a cutter, a conductive resin was applied and cured at 150 degrees for 30 minutes to obtain a molded coil.

DESCRIPTION OF SYMBOLS 1 Comparison type | mold cavity 2 Positioning pin 3 Support pin 4 Lower mold | type 5 Crevice 6 Medium mold | type 7 Embedded material 8 Sealing material cavity 9 Embedded material cavity 10 Air core coil 11 Winding terminal 12 Sealing material 13 Upper mold | type 14 Pressure punch 15 Punch 16 Burr 17 Coil molded body 18 Die tool

Claims (1)

In a method of manufacturing a mold coil in which an air-core coil is sealed with a magnetic mold resin in which a resin and magnetic powder are kneaded, the mold material is divided into two or more, one mold material is set in a cavity, A step of embedding at least a part of the air-core coil in a state where one mold material is melted, and after the embedding step, the other mold material is supplied to the sealing material cavity and the embedding material cavity, and the coil molded body is clamped Sealing is performed by fluidly pressing the magnetic mold resin in the cavity from a direction different from the embedding direction by pressing at least a part of the other mold material with a pressure punch in a state where the thickness is specified. A method for producing an integral mold coil, which is characterized.

Images