JP2011077302A - Coil and transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coil and a transformer that are not easy to get magnetically saturated while made compact and lightweight. <P>SOLUTION: The coil 1 includes a lower magnetic material substrate 2, a looped conductor 3 formed on the lower magnetic material substrate 2, a magnetic material core layer 4 provided at a periphery of the looped conductor 3, and an upper magnetic material substrate 5. Further, an air gap 6 is formed between the looped conductor 3 and magnetic material core layer 4. A gap length of the air gap 6 in a direction perpendicular to the lower magnetic material substrate 2 varies to be larger toward the looped conductor 3 and to be smaller away therefrom, and a thickness of the magnetic material core layer 4 has an in-plane distribution. Consequently, magnetic resistance of a path extending nearby the looped conductor is substantially equal to that of a path passing far away therefrom, so that magnetic flux density in a core part becomes uniform and magnetic saturation is not easily caused. The transformer includes a pair of the coils 1, and is constituted by joining each loop conductor and the core part together opposite each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coil and a transformer formed on a magnetic material substrate.

  In recent years, there has been a demand for miniaturization and weight reduction of power supplies used in small and lightweight electronic devices, and there has been an issue of miniaturization and weight reduction of magnetic elements such as coils and transformers, which are relatively large components in the power supply circuit. It is coming. For this purpose, a magnetic element is known in which a planar coil is formed on a magnetic material substrate, the planar coil is covered with a magnetic resin layer, and sandwiched between upper magnetic material substrates from above (see, for example, Patent Documents). 1).

  However, in such a magnetic element, the magnetic resistance in the path passing through the vicinity of the planar coil is smaller than the magnetic resistance in the path passing through the distance of the planar coil, so that the magnetic flux concentrates near the conductor of the planar coil. For this reason, when a large current flows through the conductor of the planar coil, the magnetic flux density is not so high at a distance from the conductor, but the magnetic flux is high in the vicinity of the conductor and magnetic saturation occurs, so that the inductance decreases. There is a problem.

JP 2007-173384 A

  An object of the present invention is to solve the above-described problems, and to provide a coil and a transformer that are difficult to be magnetically saturated while achieving a reduction in size and weight.

  In order to achieve the above object, the invention according to claim 1 is the magnetic material substrate, the loop conductor formed on the magnetic material substrate, and the loop conductor provided around the loop conductor to energize the loop conductor. A coil made of a magnetic material through which a magnetic flux generated sometimes passes, and the core has an air gap between the loop-shaped conductor, and the air gap is formed on the magnetic material substrate. The gap length in the vertical direction increases so as to approach the loop-shaped conductor and changes so as to decrease as the distance from the loop-shaped conductor increases.

  According to a second aspect of the present invention, in the coil according to the first aspect, the air gap is formed between the core portion and the magnetic material substrate.

  According to a third aspect of the present invention, in the coil according to the first or second aspect, the air gap is replaced with a material having a lower magnetic permeability than materials of the magnetic material substrate and the core portion.

  A fourth aspect of the invention comprises a pair of the coils according to any one of the first to third aspects, wherein each of the pair of coils has each magnetic material substrate positioned outside, and each loop-like conductor and core portion. They are joined so that they face each other.

  According to the first aspect of the present invention, the air gap length varies depending on the position, and the thickness of the core portion in the direction perpendicular to the magnetic material substrate has an in-plane distribution. The magnetoresistance and the magnetoresistance in the path passing through a distance can be made substantially the same. For this reason, the magnetic flux density in the core portion becomes uniform, and magnetic saturation is difficult to occur, and the overall size and weight can be reduced.

  According to the invention of claim 2, since the air gap is located between the magnetic material substrate and the core portion, the air gap is formed by a MEMS (Micro Electro Mechanical System) technology in which materials are stacked on the magnetic material substrate. It becomes easy to make and the coil can be manufactured easily.

  According to the invention of claim 3, since the air gap is replaced with a material having a low magnetic permeability, the trouble of forming the air gap is saved, and the coil can be easily manufactured.

  According to the invention of claim 4, since each coil constituting the transformer is hardly magnetically saturated, the transformer is also hardly magnetically saturated, and the same effect as that of claim 1 can be obtained.

(A) is a disassembled block diagram of the coil which concerns on the 1st Embodiment of this invention, (b) is a perspective view of the same coil. (A) is sectional drawing of the coil, (b) is the elements on larger scale of the sectional view in (a). Sectional drawing of the trans | transformer which concerns on the 2nd Embodiment of this invention.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2. The coil 1 according to the present embodiment includes a lower magnetic material substrate (magnetic material substrate) 2, a loop conductor 3 formed on the lower magnetic material substrate 2, and a loop conductor 3 provided around the loop conductor 3. Are provided with a magnetic material core layer (core portion) 4 made of a magnetic material through which a magnetic flux generated when current is passed through and an upper magnetic material substrate 5 disposed on the loop-shaped conductor 3. An air gap 6 is formed between the loop conductor 3 and the magnetic material core layer 4. The lower magnetic material substrate 2 and the upper magnetic material substrate 5 can use ferrite, the loop conductor 3 can use copper, and the magnetic material core layer 4 can use NiFe.

  The loop-shaped conductor 3, the magnetic material core layer 4, the upper magnetic material substrate 5, and the air gap 6 can be formed on the lower magnetic material substrate 2 by using, for example, a MEMS process. When the lower magnetic material substrate 2, the magnetic material core layer 4 and the upper magnetic material substrate 5 are not insulators, the loop-shaped conductor 3 is insulated and separated by covering the entire surface with an insulating layer such as an oxide film. The magnetic material core layer 4 is provided on the inner peripheral side and the outer peripheral side of the loop conductor 3. In order to make the magnetic flux density passing through the magnetic material core layer 4 uniform, the lower magnetic material in the air gap 6 is set such that the thickness of the magnetic material core layer 4 (thickness in the direction perpendicular to the magnetic material substrate) has an in-plane distribution. The gap length in the direction perpendicular to the substrate 2 is changed so as to be closer to the loop conductor 3 and to be smaller as the distance from the loop conductor 3 is increased.

  The formation of the air gap 6 is performed by once forming a member such as SiO at a position where the air gap 6 is formed and then removing the formed member. The position of the air gap 6 in the direction perpendicular to the lower magnetic material substrate 2 may be formed at any position between the lower magnetic material substrate 2 and the upper magnetic material substrate 5. However, when the air gap 6 is formed on the upper magnetic material substrate 5 side of the magnetic material core layer 4, the air is bonded by an adhesive or the like when the upper magnetic material substrate 5 is joined to the magnetic material core layer 4 after the air gap 6 is formed. There is a possibility that the gap 6 is filled. Therefore, since the loop conductor 3 and the magnetic material core layer 4 are formed on the lower magnetic material substrate 2 by the MEMS process, an air gap 6 is formed between the lower magnetic material substrate 2 and the magnetic material core layer 4. By providing, it becomes easy to manufacture the coil 1.

  Next, the function and effect of the coil 1 configured as described above will be described with reference to FIG. When the loop conductor 3 is energized, the generated magnetic flux passes through the lower magnetic material substrate 2, the magnetic material core layer 4, the upper magnetic material substrate 5, and the air gap 6. At this time, the respective magnetic resistances in the path I passing through the position close to the loop-shaped conductor 3 and the path II passing through the position away from the loop-shaped conductor 3 are simply compared with the case where there is no air gap 6. Ask. Here, the relative magnetic permeability μ1 = 1000 of the lower magnetic material substrate 2 and the upper magnetic material substrate 5, the relative magnetic permeability μ2 = 500 of the magnetic material core layer 4, and the relative magnetic permeability μ3 = 1 of the air gap 6 are set. In the path I, the length corresponding to the path passing through the lower magnetic material substrate 2 and the upper magnetic material substrate 5 is d2, and the gap length is h1, and in the path II, the lower magnetic material substrate 2 and the upper magnetic material substrate 5 are passed. The distance corresponding to the difference between the route I and the route II is d1, and the gap length is h2.

If there is no air gap 6,
Magnetoresistance HI of path I = 2 × d2 / μ1 + 2 × h3 / μ2
Magnetoresistance HII of path II = 2 × (d2 + 2 × d1) / μ1 + 2 × h3 / μ2 = 2 × d2 / μ1 + 4 × d1 / μ1 + 2 × h3 / μ2
Thus, the magnetic resistance of the path I is smaller than the magnetic resistance of the path II by (4 × d1 / μ1). Thus, when there is no air gap 6, the magnetic resistance is smaller in the path passing through the position close to the loop conductor 3 than in the path passing through the far position, so that the magnetic flux is closer to the loop conductor 3. concentrate.

If there is an air gap 6,
Magnetic resistance HI of path I = 2 × d2 / μ1 + 2 × (h3−h1) / μ2 + 2 × h1 / μ3 = 2 × d2 / μ1 + 2 × h3 / μ2 + 2 × h1 (1 / μ3-1 / μ2)
Magnetoresistance HII of path II = 2 × (d2 + 2 × d1) / μ1 + 2 × (h3-h2) / μ2 + 2 × h2 / μ3 = 2 × d2 / μ1 + 2 × h3 / μ2 + 2 × h2 (1 / μ3-1 / μ2) +4 × d1 / μ1
It becomes.
Where d1 = (h1-h2) × (1 / μ3-1 / μ2) × μ1 / 2 = 499 × Δh (where Δh = h1-h2)
If so, the magnetic resistance HI of the path I and the magnetic resistance HII of the path II are the same. For example, if d1 = 1 mm and h2 = 0 μm, the magnetic resistance HI and the magnetic resistance HII are the same when h1 = 1000 / 499≈2 μm. Therefore, when the cross section of the air gap 6 is a right triangle having a base of 1 mm and a height of 2 μm, the magnetic resistance at the position from the loop conductor 3 to a distance of 1 mm is substantially the same, so the magnetic flux density in that range is uniform. Become.

  In this way, by changing the air gap length and giving the thickness of the magnetic material core layer 4 an in-plane distribution, the magnetic resistance in the path passing near the loop-like conductor 3 and the path passing far is substantially the same. As a result, the magnetic flux density in the magnetic material core layer 4 becomes uniform and magnetic saturation is difficult, and the coil 1 can be easily reduced in size and weight.

  In addition, the formation of the air gap 6 requires a thickness control in units of μm. However, the cross section shown in FIGS. 2A and 2B is not a right triangle, and the cross section of the hypotenuse is a stepped shape. Even if it is a shape, if the relationship between the base and the height is maintained, substantially the same effect can be obtained.

  In the present embodiment, the configuration in which the loop-shaped conductor 3 and the magnetic material core layer 4 are sandwiched between the pair of the lower magnetic material substrate 2 and the upper magnetic material substrate 5 is shown. If it is good, the upper magnetic material substrate 5 can be omitted.

  Next, a modification of this embodiment will be described. In the above embodiment, the air gap 6 is an example of the air gap itself. However, the air gap 6 has a permeability higher than that of the material of the lower magnetic material substrate 2, the upper magnetic material substrate 5, and the magnetic material core layer 4. A gap that is replaced with air by forming, for example, SiO, which is a low material, may be used. The relative magnetic permeability of the material having low magnetic permeability is preferably in the range of 1 to 10. By adjusting the length of the gap, the magnetic resistance in the magnetic material core layer 4 becomes substantially the same, so that the magnetic flux density becomes uniform. As described above, by replacing the air gap 6 with a member having a low magnetic permeability, the trouble of forming the air gap 6 can be saved and the coil 1 can be easily manufactured.

(Second Embodiment)
A second embodiment will be described with reference to FIG. In the present embodiment, a transformer is configured using the coil 1 according to the first embodiment. The transformer 7 includes a pair of coils 1 and 1. Each coil 1 has a configuration excluding the upper magnetic material substrate 5, and the transformer 7 has the lower magnetic material substrate 2 of each coil 1 positioned outside, and the loop conductor 3 and the magnetic material core layer 4 face each other. Are joined together. With such a configuration, each coil 1 is magnetically coupled to operate as a transformer 7, and each coil 1 is hardly magnetically saturated, and the transformer 7 is also difficult to be magnetically saturated.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, the loop conductor 3 may have a plurality of turns instead of one turn.

1 Coil 2 Lower magnetic material substrate (magnetic material substrate)
3 Loop conductor 4 Magnetic material core layer (core part)
5 Upper magnetic material substrate 6 Air gap 7 Transformer

Claims (4)

A magnetic material substrate; a loop-shaped conductor formed on the magnetic material substrate; and a core portion made of a magnetic material provided around the loop-shaped conductor and through which a magnetic flux generated when the loop-shaped conductor is energized passes. In a coil comprising
The core portion has an air gap between the loop-shaped conductor,
The coil is characterized in that the air gap changes such that a gap length in a direction perpendicular to the magnetic material substrate increases as it approaches the loop conductor and decreases as it moves away from the loop conductor.   The coil according to claim 1, wherein the air gap is formed between the core portion and the magnetic material substrate.   The coil according to claim 1 or 2, wherein the air gap is replaced with a material having a lower magnetic permeability than materials of the magnetic material substrate and the core portion. A pair of the coils according to any one of claims 1 to 3,
The transformer is characterized in that the pair of coils are joined such that each magnetic material substrate is located outside and each loop-shaped conductor and the core portion face each other.

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