JP4705191B1 - Molded coil manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a method of manufacturing a mold coil that is low in cost and high in characteristics and reliability, in which the mold structure is not complicated, the molding process can be simplified, the mold position and dimension variation of the winding are small. To do.
[Solution]
The mold coil manufacturing method of the present invention is a mold coil manufacturing method in which a coil is sealed with a mold resin in which a resin and a magnetic powder are kneaded using a plastic compression molding method. It is characterized by compression molding after embedding. In addition, the coil terminal is exposed to the outside of the kneading resin at the time of embedding, and presses the mold surface that slides on the exposed portion, and then the kneaded material, the winding exposed portion, and the mold are brought into close contact with each other and then compression molded. To do.
[Selection] Figure 4

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.

  In view of this, the applicant proposed in Japanese Patent Application No. 2009-267350 filed earlier that a high-precision molded coil can be formed at low cost by embedding windings with high precision by a plastic molding method, with less material loss.

JP 2007-49073 A

  In Japanese Patent Application No. 2009-267350 filed earlier, it is a method of manufacturing a coiled integral mold coil using a plastic compression molding method, which comprises a punch sliding with a cavity, FIG. 1 positioning pin 2, support pin 3 and the like. This is a technique in which the mold resin is pressure-molded stepwise after using the formed mold and holding the winding at the position specified by the positioning pin 2 and the support pin 3.

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.

In a method of manufacturing a mold coil in which a coil is sealed with a magnetic mold resin in which a resin and magnetic powder are kneaded, a mold material 4 is placed in a mold 5 shown in FIG. 2, and the winding 6 shown in FIG. A molded coil is manufactured by using a plastic compression molding method of embedding and press molding with a pressure punch 11 in FIG.

FIG. 2 shows a mold coil manufacturing method in which the mold material 4 is formed into a predetermined shape before the winding 6 is embedded.

A method for manufacturing a molded coil, wherein the winding terminal 8 is exposed to the outside of the molding material 4 when the winding 6 is embedded, and is pressed with a pressing die 9, followed by compression molding.

The method for producing a molded coil, wherein the kneaded material contains inorganic powder or the like other than resin in a volume ratio of 65% or more.

  The method for manufacturing a molded coil according to the present invention is a method for manufacturing a molded coil in which a winding 6 is embedded in a mold material 4 that has been previously melted in a clay shape in a cavity, and then plastic compression molding is performed.

In this manufacturing method, it is not necessary to move the positioning pins 2 and the support pins 3 in the pressurized magnetic resin such as the bottom of the mold as in Japanese Patent Application No. 2009-267350. The pressure process can be simplified, which is advantageous in terms of man-hours and machine costs.

Further, in this method, it is possible to eliminate the positioning pin 2 and the support pin 3 at the time of pressure curing, so that a cured resin or the like enters the gap between the positioning pin 2 and the guide of the support pin 3. And distortion of the mold can be suppressed.

  Further, in the step of embedding the winding 6, the winding terminal 8 is pulled out of the melted magnetic resin, and the terminal surface is pressed against the magnetic resin while pressing the pulled terminal surface with the cavity side surface of the drawn surface. It can be located near or outside.

  Since the lead terminal surface can expose the side surface of the wire, for example, when the external electrode is formed of a conductive resin or the like, the contact surface can be increased and the bonding reliability can be increased.

In addition, since the resin flows on the pressing surface 7 is almost formed only at the upper part of the winding 6 embedded therein and molded, the accuracy of the embedded position can be easily obtained with little movement of the winding 6. Therefore, variations in electrical characteristics and defects in appearance are unlikely to occur.

Further, a material containing 65% or more by volume ratio of inorganic powders other than resin in the kneaded material has an appropriate viscosity, and it is difficult for movement of the winding to occur and variations in characteristics are unlikely to occur.

FIG. 1 is a perspective view showing a mold structure used for explaining a conventional construction method. FIG. 2 is a perspective view for explaining the state of the mold and mold material used in the embodiment of the present invention. FIG. 3 is a perspective view for explaining an embedded state of the winding used in the embodiment of the present invention. FIG. 4 is a perspective view for explaining the terminal exposure mechanism used in the embodiment of the present invention. FIG. 5 is a perspective view for explaining the compression molding state of the molded coil used in the embodiment of the present invention.

  The mold coil manufacturing method of the present invention is obtained by filling a mold material 5, which is a magnetic material kneaded material made of a powder additive and a thermosetting resin, into a mold 5 cavity and then winding the winding 6 in the mold material 4. After being buried under pressure, the winding is further molded in the resin by pressurization.

The magnetic mold material kneaded material preferably contains 65% or more by volume ratio of inorganic powder other than resin. This is because a kneaded product of 65% or less has a soft melt viscosity, and it is difficult for the embedded winding to maintain a specified position, and a characteristic defect due to misalignment tends to occur.

It is desirable that the kneaded material to be put in the mold is previously molded into a size that fits in the mold to a specified weight. FIG. 2 shows an example in which the molding material 4 is formed into a rectangular parallelepiped that fits perfectly in the mold. The size of the coil (in the embodiment, the height of the mold coil) can be controlled by adding the specified weight, and when it is molded to a size that fits perfectly into the mold, the side surface of the cavity and the molding material 4 are almost the same when the winding 5 is embedded. It will be in close contact, and there will be little resin flow by subsequent compression molding, and it is possible to reduce the shift | offset | difference of the winding position in a molding body.

It is desirable that the wire to be embedded in the kneaded material is bonded to some extent in advance using a fused wire or the like. This is because it is considered that the shape of the winding is deformed by pressurization at the time of embedding and affects the characteristics.

In addition, the wire is preferably a person who can take many joint surfaces between the wires, such as a flat wire. In addition to strong adhesive strength, the gaps between the windings can be reduced, so that the cavities in the molded body can be reduced, and the electrical characteristics, mechanical characteristics, and environmental resistance characteristics are improved.

  If the molding material 4 is placed at a predetermined position near the center of the pressure punch 11, the embedded winding 6 is less likely to be displaced during pressure molding, and variations in characteristics and the like are reduced. You may provide the mechanism which dents and the other position in a type | mold in order to install in a predetermined position.

The winding 6 is preferably embedded with a pressing mechanism whose position is firmly determined and a mechanism that can hold the winding firmly so that the winding 6 can be embedded in a predetermined position in the molten kneaded resin.

The winding 6 to be molded needs to be electrically connected to the external electrode. When joining with a plate-shaped metal, it is desirable to embed a pre-joined winding wire at a predetermined position and then press the side surface with the pressing die 9 while pressing it with a winding pressing mechanism. This is desirable because the external electrode can be easily exposed to the outside without shifting the winding position, but if it can be embedded at an appropriate position with high accuracy, the kneaded resin will flow toward the mold during embedding and pressure molding. Therefore, it is possible to expose without a presser mold.

Further, in the case of an external electrode made of a conductive resin or the like, there is a high possibility of disconnection or high resistance when only the cross section of the winding is connected. Embedding the wound end face outside the melted kneaded resin, and suppressing the exposed part with the presser mold while pressing with the winding pressing mechanism is desirable because the position of the internal electrode is less likely to be exposed and the side of the winding is easily exposed. However, if the embedding position is appropriate as in the case of the plate-like metal external electrode, the presser mold is not necessary.

Since the device for embedding the winding moves from the mold after the embedding and before the kneading resin is cured, the removal process and wear of the holding portion and the embedding portion are compared with the conventional support pin 3 and positioning pin 2 mechanism shown in FIG. Etc. are reduced.

  Pressurize with a pressure punch 11 to cure. In FIG. 5, the upper kneaded resin is mainly flowed under pressure in the winding embedded during pressurization. Since most of the kneaded resin that flows to mold is in the upper part of the winding, it is difficult for the winding to be misaligned during pressurization.

  When a mold coil is manufactured by such a method, compared with the case where the mold of FIG. 1 is used, it is not necessary to divide the pressure by the mold into several stages, and the mechanism of the molding die can be simplified. Processing costs can be reduced and manufacturing costs can be reduced.

After mixing 8 wt% of an epoxy resin mixture containing 92 wt% of amorphous magnetic powder and an equivalent amount of novolac type epoxy resin and phenol novolak type resin in a kneader at 110 degrees 40 minutes, add 0.1 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 raw material powder was placed in a die so that the mixed powder had an average of about 27 mg in a die shape of 2.30 mm * 1.8 mm square, and a rectangular input material 4 was obtained by powder compression molding.

The input material 4 was placed at a predetermined position in the mold 5 in FIG. 2 preheated to 150 degrees.

A winding 6 wound in advance and externally with a self-bonding rectangular wire having a height of 0.5 mm, a length * width of 2.3 * 1.8 mm and an ellipse at the center was embedded at a predetermined position from the pressing surface 7. At this time, in Example 1, the winding terminal 8 was embedded so as to come out of the mold material 4.

    Next, while pressing the winding 6 to be buried so as not to move upward, the pressing die 9 was moved so that the longitudinal dimension of the cavity was 2.5 mm, and the winding terminal 8 was brought into close contact with the pressing die 9.

A pressure punch 11 preheated to 150 degrees in advance was placed in a cavity surrounded by the mold 5 and the pressing die 9 and cured for 10 minutes while applying pressure, whereby a coil molded article 10 was obtained.

After removing burrs and the like by a predetermined method, the wire covering of the winding terminal 8 was removed, and a conductive resin was applied and cured to obtain a molded coil.

  Winding integral molding mold coil using plastic compression molding does not require a complicated mold structure, can embed the winding with high accuracy, reduce manufacturing costs, and suppress variations in characteristics and reliability. High performance molded coil can be manufactured.

DESCRIPTION OF SYMBOLS 1 Comparison type | mold 2 Positioning pin 3 Support pin 4 Mold material 5 Mold 6 Winding 7 Pressure surface 8 Winding terminal 9 Pushing die 10 Coil molding 11 Pressure punch

Claims (2)

    In a method of manufacturing a mold coil in which a coil is sealed with a mold resin obtained by kneading a resin and a magnetic powder, the kneaded mold resin is pulverized using a plastic compression molding method in which the resin contained is melted and then pressure-molded. Thereafter, a step of powder compression molding to a predetermined size, a step of installing the powder compression molding body at a predetermined position in the cavity, a step of melting the powder compression molding body, and the molten powder compression molding body A method for producing a mold coil, comprising: embedding a winding wire from one direction; and pressurizing the embedded surface to flow the mold resin on the embedded surface. The end of the winding is embedded so that the end of the winding is outside of the kneaded material, and the mold surface of the end exposed surface slides, and the end exposed surface and the kneaded material The method for producing a molded coil according to claim 1, wherein the plastic is compression-molded after adhering.

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