JP2007095882A - Manufacturing method of choke coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a manufacturing method of a surface-mounting choke coil having all-out crack solution even in a structure with little magnetic leakage as parts used for a high-density integrated circuit, with a small shape adopted in the drive circuit for the latest low voltage and large current as a choke coil for a personal computer. <P>SOLUTION: A coil having 3.5 Ts winding with a straight-angle wire (copper wire) of 1.8 mm of width×0.5 mm of thickness is applied with epoxy resin XA-1189-2BK (brand name) according to the coil adhesion securing conditions concerning the number of adhesion parts, or adhesion width. Then, simultaneous embedding molding is performed to the coils which are hardened by adhesion securing for 30 minutes at 120°C, so that the coil having the length of 10 mm, the side of 10 mm and the height of 4 mm may carry out the embedding compression molding at the molding pressure of 5 ton/cm<SP>2</SP>, so as to manufacture a core and a coil integral choke coil by hardening, sequentially, for 30 minutes at curing temperature 70°C, for 20 minutes at 150°C and for 10 minutes at 170°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a rectangular coil-embedded power choke coil using pure iron, an iron-based alloy, an amorphous alloy, and a metal magnetic material manufactured by other metallurgical methods.

Power choke coils used in recent low-voltage, large-current drive circuits are used for high-density mounting, so they have a structure with little magnetic leakage, a small inductance change rate with respect to DC current, and small size A shape with a length of 15 mm, a width of 15 mm, and a height of 6 mm or less is highly demanded by the market.
On the other hand, ferrite has a low saturation magnetization characteristic of 0.4 to 0.5 Tessler, and iron, amorphous, and other metallic magnetic materials used in the present invention have a high saturation magnetization of 1.0 Tessler. However, it is being adopted instead of ferrite.
However, metal-based magnetic material powders have low insulation resistance, and due to eddy current loss at high frequencies, the magnetic properties other than direct current superposition characteristics of inductance are not as good as those of ferrite. Insulating treatment is performed using various methods and various insulating materials in order to subject the material powder to insulation treatment.
A large current choke coil mainly composed of a personal computer used in a high-density integrated circuit has a structure with little magnetic leakage and is required to be small.
In order to cope with a large current, the conventional copper wire having a round cross-sectional area has been changed to the use of a copper wire (square wire) having a square cross-sectional area and a large surface area.
When a flat wire is wound in a coil shape and embedded in a metal powder and molded integrally, the surface-coated resin to obtain high insulation is cured after molding, and the coil springback As a result, there are many phenomena that cause cracks on the product surface.
Conventionally, as a solution to this, in order to cope with a large stress change that occurs in the shape due to the springback when the metal powder is embedded and simultaneously molded and cured, the powder is uniformly distributed between the layers of the coil that is wound several turns at the time of molding. In general, manufacturing is performed such that cracking is prevented by forming the material into a mold and dispersing the generated stress between metal powders.
In this method, the inner surface of the molding cannot be seen, the powder is evenly distributed between the coils, or it is necessary to devise some sort of molding machine or mold at the time of molding, and there is a problem in reproducibility. Even with a structure that minimizes the stress of the coil at the time of molding, no complete crack solution has been reached.
In addition, even when an impact is applied to the drum core or a reduction in height is achieved, a choke coil in which the drum core is hardly cracked is known (see Patent Documents 1 and 2).

JP 2002-64023 A JP 2002-64024 A

  Therefore, the present invention is entirely applicable to a choke coil for a personal computer having a small shape employed in a recent low voltage and large current drive circuit and a structure having little magnetic leakage as a component used in a high density integrated circuit. It is an object of the present invention to obtain a method for manufacturing a surface mount type choke coil having a crack solution.

The choke coil manufacturing method of the present invention is a choke coil manufactured by solidifying a pure iron, iron alloy, amorphous alloy and other alloy magnetic material powder in which the coil is embedded, and the coil is preliminarily provided at two or more locations through the entire coil turn. The choke coil molding method is characterized in that a width of 1 mm / location or more and a gap of 2 mm or more between the fixing resins are opened and fixed with an epoxy resin, and then embedded and simultaneously molded.
Furthermore, in the choke coil having a coil of 15 mm in length, 15 mm in width, and 6 mm or less in height, the coil is a flat wire with several turns, molded at an embedding pressure of ² to 5 ton / cm ² and having an inductance of 1.5 μH It is as follows.

  According to the choke coil manufacturing method of the present invention, the coil spring back is substantially cracked by the coil spring back after being hardened by embedding it in a metal powder by containing stress from the beginning with an epoxy resin. And a good quality choke coil was obtained.

Hereinafter, specific examples of the method for manufacturing the surface mount type choke coil of the present invention will be described in detail with reference to the drawings.
In the present invention, pure iron, iron-based alloy, amorphous alloy, and other alloy-based powders are added with high-temperature heat-resistant epoxy resin, and further subjected to surface insulation treatment, and the metal magnetic material powder is produced by a powder metallurgical manufacturing method. In this case, a rectangular coil is embedded, and an epoxy resin is cured at 70 ° C. to 170 ° C. to produce a small-sized power choke with little leakage magnetic flux that meets market requirements.
At that time, the embedded 1-5 Ts rectangular coil is sealed in the insulated metal magnetic material powder at a molding pressure of 2-5 ton / cm ² , but when the surface-coated epoxy resin is cured, the coil springback Cracks will appear on many product surfaces.
Until now, to solve this crack, a special molding method such as inserting metal-based magnetic material powder between uniform coils in the range of several μm to several tens of μm during molding for the purpose of buffering stress between coils as described above. It has been solved.
According to the present invention, the coil springback is cracked due to the coil springback also by the epoxy resin (adhesive) containing the stress from the beginning and embedding it in the metal magnetic material powder and curing the epoxy resin. It is possible to greatly improve the problem caused by.

First, an iron (Fe) -silicon (Si) -aluminum (Al) -based sendust atomized alloy powder having a ratio of powder having protrusions with a radius of curvature equal to or less than one-half of the grain radius is reduced to 600% in the atmosphere. C. and 1 Hr firing.
A surface coating solution in which 2.4 kg of insulating layer forming treatment liquid (1.2 kg of epoxy resin, 1.2 kg of methyl ethyl ketone) is sprayed on a state where 30 kg of the obtained alloy powder is floated and stirred with warm air to coat the surface of the alloy powder. To do.
Furthermore, granulation was performed while spraying the insulating layer forming treatment solution continuously, and methyl ethyl ketone was completely evaporated by natural drying, and granules were produced through a 355 μm net (355 μm under sieve).
Next, 300 g of talc was added in order to prevent agglomeration of the granule having an insulating layer formed on the surface thereof to improve the moldability and the epoxy resin coated with the granule surface, thereby producing a mixed molding powder.
An epoxy resin XA-1189-2BK (product name) under a coil bonding and fixing condition of the number of bonding points and the bonding width of a coil wound with 3.5 Ts with a flat wire (copper wire) of 1.8 mm width × 0.5 mm thickness ), And the coil fixed at 120 ° C for 30 minutes is embedded and embedded, and the coil is compression-molded with a molding pressure of 5 ton / cm ² and 10 mm in length, 10 mm in width, and 4 mm in height. Curing was performed for 30 minutes, 150 ° C. for 20 minutes, and 170 ° C. for 10 minutes to produce a choke coil integrated with a core and a coil.

The coil bonding and fixing conditions of the choke coil manufactured as described above are shown in the bonding location of FIG. 1 and the bonding width of FIG.
1 are linear and have a width of 1 mm, a total of two locations, one on each of the A direction side and the B direction side, two on each of the A direction side and the B direction side, and the A direction side. 2 and 3 in each of the B direction sides, the adhesive width of FIG. 2 is 5 patterns of adhesive widths of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm on the A direction side and B direction side (2 places) in the middle of the lead ends. Glued with.
In FIG. 1 and FIG. 2, (a) and (b) are common bonding portions of the terminal lead bent portion, and (c) is a coil.
FIG. 3 is a graph showing the relationship between the yield of cracks after curing under the bonding conditions shown in FIG.
From FIG. 3, it can be seen that there are slight cracks occurring at the four adhesion points, and no cracks after curing are obtained, and the yield is 100%, and the yield is improved by 30% at the two points. There was only a 10% improvement at one location on one side. It can be seen that the effect is obtained in two or more places.
FIG. 4 is a graph showing the relationship between the yield of cracks after curing under the bonding conditions shown in FIG.
As shown in FIG. 4, the adhesive width is 4 mm or more, and there is no generation of cracks after curing, and the yield of cracks is 100%. The adhesive width is 3 mm, 90%, the width is 2 mm, 60%, and the width is 1 mm. You can see the effect.
In FIG. 1, if the gap between the bonded portions, that is, the gap between the fixed resins is less than 2 mm, workability is poor and 2 mm or more is preferable. Further, since the length of the outer periphery of the rectangular wire coil is finite, the number of bonding points is also limited.

5 (1) to (4) show the bonding location, the coil bonding fixing condition of the bonding width, and the occurrence of cracks from the left.
In FIG. 5 (1), 100% cracks occur horizontally at the core center position without adhesive fixing.
Fig. 5 (2) shows the occurrence of cracks when there is one piece each for the A direction side and the B direction side having a width of 1 to 2 mm, and one place for each of the adhering part A direction side and the B direction side with an adhesive width of 1 mm. Indicates.
Fig. 5 (3) shows the occurrence of cracks when there are two adhesive points A direction side and B direction side each having a width of 1 to 2 mm, and when the adhesive width is 3 mm and there is one point each on the adhesive portion A direction side and B direction side. Indicates.
Fig. 5 (4) shows the occurrence of cracks when there are 3 pieces each on the A direction side and the B direction side with a width of 1 to 2 mm, and one place each on the A direction side and the B direction side with a bonding width of 4 mm. Indicates.
There is no crack at all.
As an example, an example of an iron-silicon-aluminum alloy was given. However, cracks were generated using powders such as pure iron, iron-based alloys, amorphous alloys, and alloy-based magnetic materials (for example, permalloy) as metal magnetic materials. But the same effect was obtained.

It is explanatory drawing which shows the adhesion | attachment method of a linear adhesion | attachment location change. It is explanatory drawing which shows the adhesion | attachment method of a linear adhesion | attachment width change. It is a graph which shows the relationship with the yield of a crack of a linear adhesion part change. It is a graph which shows the relationship with the yield of a crack of a linear adhesive width change. (1) It is explanatory drawing which shows the generation | occurrence | production state of a crack when there is no adhesion part and no adhesion width. (2) It is explanatory drawing which shows the generation | occurrence | production state of a crack when the adhesion location A direction side and the B direction side are each one location and the adhesion width is 1 mm. (3) It is explanatory drawing which shows the generation | occurrence | production state of a crack when the adhesion location A direction side and the B direction side are each 2 locations and the adhesion width is 3 mm. (4) It is explanatory drawing which shows the generation | occurrence | production state of a crack when the adhesion location A direction side and the B direction side are each 4 locations and the adhesion width is 4 mm.

Explanation of symbols

B Lead bonding area B Lead bonding area C Coil

Claims (1)

In choke coils made by solidifying solid iron, iron-based alloy, amorphous alloy and other alloy-based magnetic powder, rectangular wire coils are preliminarily placed in two or more locations throughout the entire turn, width 1mm / location, A method for manufacturing a choke coil, comprising: fixing with a gap of 2 mm or more between fixed resins, and then simultaneously embedding.

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