JP2003007540A - Thin magnetic core and magnetic part using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve production yield after resin coating by keeping the shape of a wound body in high reproducibility and prevent degrading of characteristic accompanied with welding, in a magnetic core using a thin wound body. SOLUTION: This thin core is formed by winding a magnetic thin band around a core and applying insulation coating thereto. The inner diameter side thin band and outer diameter side thin band are welded over a plurality of layers. In this case, the welding depth (b) is 30 μm or more, the percentage ([(a×b)/V]×100(%)) of a product of a total area of welded part (a) and the welding depth (b) to a volume(V) of the magnetic thin band is 5% or less, and the percentage ((a1 /S)×100(%)) of a total area of welded part on inner diameter side (a1 ) to an area of core inner diameter side(S) is 15% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and thin magnetic core used for pulse transformers and the like, and a magnetic component using the magnetic core.

[0002]

2. Description of the Related Art In recent years, as a constituent material for transformer cores and choke coil cores used in various electric and electronic parts such as power supply circuits and communication circuits, high permeability and loss in high frequency range have been achieved. Amorphous magnetic alloys have come to be widely used because of their characteristics such as small magnetic flux density and high saturation magnetic flux density.

In the case of forming a magnetic component with the above-mentioned amorphous magnetic alloy, first, the thinned amorphous magnetic alloy is wound to form a magnetic core, and the magnetic core is wound to produce a magnetic component. Is common. At this time, since the amorphous magnetic alloy ribbon has conductivity, the winding is performed after the surface (outer peripheral surface) of the core is insulation-coated.

The insulating coating of the magnetic core is carried out by applying a resin coating on the surface of the core or by housing the core in a resin case. The resin coating of the magnetic core is performed by, for example, applying resin powder for coating on the surface of the winding body of the amorphous magnetic alloy ribbon by spraying, or by dipping it in a resin impregnating solution and then applying the resin by thermosetting. It is carried out by

By the way, the magnetic core and the magnetic parts using the magnetic core are required to be further reduced in size and thickness in order to enable high-density mounting. For example, PC cards for personal computers and portable information terminals (PD
A) In addition, it is strongly required to reduce the thickness of magnetic parts used in mobile communication devices. For example, the height (width of the magnetic alloy ribbon) is 5 mm or less, and A thin magnetic core (rolled body) having an outer diameter ratio of more than 2 has come to be used as a pulse transformer or the like.

Thin magnetic core (rolled body) as described above
Then, since the shape easily collapses from the end, when winding a soft magnetic alloy ribbon such as an amorphous magnetic alloy ribbon,
First, after end welding to the two layers of magnetic ribbon on the inner diameter side,
The magnetic ribbon is wound so as to have a desired core shape, and finally two layers of the magnetic ribbon on the outer diameter side are welded or taped.

[0007]

By the way, in the conventional thin magnetic core as described above, when the outer surface of the wound body is coated with resin, the end is welded even though the end is welded. Peeling may occur from the part.
It is considered that this is due to stress or the like generated during resin coating, and in the thin magnetic core as described above, the stress during coating acts in the direction of peeling the welded portion.

Due to the peeling from the end portion as described above, the conventional thin magnetic core has a problem that the manufacturing yield is low. Therefore, it has been strongly desired to improve the manufacturing yield of the thin magnetic core by preventing the thin magnetic core from peeling off. Further, if such welding stoppers are frequently used to improve the manufacturing yield, the characteristics such as iron loss may be significantly deteriorated.

The present invention has been made to address such a problem, and enables the shape of the wound body to be maintained with good reproducibility even when a thin wound body is used. The purpose of the present invention is to provide a thin magnetic core with improved manufacturing yield and suppressed deterioration of characteristics such as iron loss. Furthermore, by using such a magnetic core, it is possible to make it smaller and thinner. The purpose is to provide a magnetic component with improved reliability and characteristics.

[0010]

A thin magnetic core of the present invention is a thin core in which an insulating coating is applied to a core around which a magnetic ribbon is wound. It is characterized by being welded over multiple layers.

By welding the inner-diameter ribbon and the outer-diameter ribbon of the core over a plurality of layers, it is possible to effectively prevent the wound magnetic ribbon from peeling off due to stress or the like generated during resin coating. can do.

The depth (b) of the welded portion is preferably 30 μm or more, and the percentage of the product of the total area (a) of the welded portion and the welded depth (b) with respect to the volume (V) of the core. ([(A × b) / V] × 100 (%)) is 5%
The following is preferable.

Welding to a depth of at least 30 μm or more, and the total area (a) of the welded portion with respect to the volume (V) of the magnetic ribbon
By setting the percentage of the product of the welding depth (b) and the welding depth (b) to 5% or less, it is possible to effectively suppress the peeling of the magnetic ribbon and the like, and also suppress the deterioration of the characteristics such as the iron loss due to the welding. You can

Further, the percentage ((a ₁ / S) × 1) of the total area (a ₁ ) of the welded portion on the inner diameter side with respect to the area (S) on the inner diameter side of the core.
00 (%)) is preferably 15% or less. The area of each weld is preferably 0.2 mm ² or less, and the total number of these welds is preferably 2 to 20.

The thickness of the magnetic ribbon used in such a thin magnetic core is preferably 30 μm or less, and the material thereof is preferably an amorphous alloy or a fine crystal alloy.

The width of the core wound with such a magnetic ribbon is preferably 5 mm or less, and the core is preferably provided with an insulating coating made of, for example, a fluorine resin.

The magnetic component of the present invention is characterized by including the thin magnetic core as described above and the windings formed on the magnetic core.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Modes for carrying out the present invention will be described below. FIG. 1 is a perspective view showing a main part (core body 1) of a thin magnetic core according to an embodiment of the present invention. FIG. 2 is a sectional view showing the overall structure of the thin magnetic core 2.

The core body 1 used for the thin magnetic core 2 of the present invention is manufactured by winding the magnetic ribbon 3 and the plurality of magnetic ribbons 3 on the inner diameter side and the outer diameter side of the core body 1 are formed. It is fixed by terminal welding (welds 4, 5) across the layers.

As shown in FIG. 2, a resin coating layer 6 made of a thermosetting insulating resin such as a fluororesin or an epoxy resin is formed on the outer peripheral surface of the core body 1, whereby the thin magnetic core 2 is formed. Is configured.

As shown in FIG. 3, the end welding of the end portion of the core body 1 on the inner diameter side is performed by a welding portion 4 so as to cover a plurality of layers of magnetic ribbons 3. For example, assuming that the innermost magnetic ribbon 3a is the first layer, the welded portion 4 is formed so as to reach the second layer magnetic ribbon 3b and the third layer magnetic ribbon 3c wound thereon. Is provided. Similarly, the outer diameter side end portion is also provided with the welded portion 5 so as to extend over a plurality of layers of the magnetic ribbon 3.

In this way, end welding is performed over a plurality of magnetic ribbons, in other words, end welding is performed on the inner and outer magnetic ribbons over two or more magnetic ribbons. Thus, the fixed state of the wound body can be made strong and stable.

Therefore, even if stress is generated when the resin coating layer 6 is formed on the outer surface of the wound body, it is possible to prevent peeling from the inner diameter side end portion and the outer diameter side end portion, and the thin magnetic layer is formed. The manufacturing yield of the core 2 can be significantly increased. Specifically, stress is applied to the magnetic core such as coating method using resin powder such as spray coating of resin powder, resin impregnation by dipping core in resin solution, or heat shrinkage of resin by heat treatment. Peeling (splitting) of magnetic ribbon even if an easy method is applied
It becomes difficult for problems such as

When the welding depth of the welded portions 4 and 5 is b, the welding depth b is preferably 30 μm or more, for example. The welding depth b depends on the thickness of the magnetic ribbon, but by setting it to at least 30 μm or more, the magnetic ribbon can be effectively fixed. The welding depth b is the average value of the welding depth of each welded portion. Regarding the individual welding depth, the deepest position in each weld is treated as the depth of the weld.

In the present invention, in such a case, the percentage of the product of the total weld area a and the welding depth b (hereinafter referred to as the weld volume ratio) to the core volume V may be 5% or less. preferable. The formula is as follows. [(A × b) / V] × 100 ≦ 5

When the amorphous alloy ribbon is wound to form the core and then the ends of the amorphous alloy ribbon are fixed by welding, the welded portion may be crystallized by the heat of welding. is there. Therefore, the characteristics of the welded portion are lower than those of the non-welded portion, and if the welded portion is too much, the characteristics of the entire core deteriorate.
In the present invention, the welding volume ratio is set to a certain value or less, so that the deterioration of the core characteristics due to such welding can be suppressed.

That is, the product of the total weld area a and the welding depth b indicates the volume of the substantially welded portion, and the percentage of this weld volume to the core volume is set to a certain value or less, thereby It is possible to suppress deterioration of characteristics, for example, increase of iron loss.

The weld volume ratio is more preferably 1% or less. With such a welding volume ratio, it is possible to further suppress deterioration of characteristics, for example, increase of iron loss.

The core volume V represents the volume of the magnetic ribbon forming the core, and the total weld area a is the area of each weld formed on the inner diameter side surface and the outer diameter side surface of the core body. Is the sum of. As the welded portion, the recess formed by welding may be regarded as the welded portion,
The portion crystallized by welding may be regarded as a welded portion.

The area of the portion thus considered to be the welded portion may be directly obtained by using an electron microscope or the like, or for simplicity, the individual welded portions may be regarded as circular,
The maximum diameter may be used as the diameter R, and may be calculated from an equation for calculating the area of a circle. For example, it is calculated by the following formula. Welded part total area a = (R / 2) ² × 3.14 × (number of welded parts)

Further, in the present invention, the inner diameter side surface of the core
Let S be the product, and let the total area of the weld on the inner diameter side of the core be a₁And
In this case, the total surface of the welded part on the core inner diameter side with respect to the area S on the core inner diameter side
Product a ₁It is preferable to keep the percentage of
Good The formula is as follows. (A₁/ S) × 100 ≦ 15

As described above, the percentage of the total area a ₁ of the core inner diameter side welded portion with respect to the area S of the core inner diameter side is set to a fixed value or less, so that the strength of the fixed portion of the magnetic ribbon on the core inner diameter side is secured and the welding is performed. It is also possible to suppress a partial deterioration in characteristics caused by the concentration of the portions on the inner diameter side of the core.

The number of welded portions as described above is preferably within 20 on the inner diameter side and the outer diameter side in total.
The larger the number of welded portions, the more reliably the magnetic ribbons can be fixed to each other, but if the number of welded portions is too large, a decrease in characteristics such as an increase in iron loss occurs.

As the magnetic ribbon 3 used in the present invention,
Examples thereof include Co-based and Fe-based amorphous magnetic alloy ribbons, Fe-based soft magnetic alloy ribbons having fine crystal grains (hereinafter referred to as Fe-based microcrystalline alloy) ribbons, and the like.

[0035] As the above-mentioned amorphous magnetic alloy thin ribbons, for example, the general _{formula: (M 1-a M '} a) 100-b X b ( wherein, at least 1 M is selected from Fe and Co
Seed elements, M'is Ti, V, Cr, Mn, Ni, C
u, Zr, Nb, Mo, Ta, W and the like, at least one element is selected, X is at least one element selected from B, Si, C, P and the like, and a and b are each 0 ≦ a ≦ 0.15, 10 ≦ b ≦ 35 atomic% are satisfied) and the composition is substantially represented.

Further, as the Fe-based fine crystal alloy ribbon,
General _{formula: Fe 100-c-d-} e-f-g-h A c D d
E _e Si _f B _g Z _h (wherein A is at least one element selected from Cu and Au, D is a 4A group element, 5A
E is Mn, Al, Ga, Ge or I, and at least one element selected from Group 6 elements, Group 6A elements and rare earth elements is used.
n, Sn and at least one element selected from platinum group elements, and Z is at least selected from C, N and P
Represents one element, and c, d, e, f, g and h are 0
≤c≤8, 0.1≤d≤15, 0≤e≤10, 0≤f≤
25, 1 ≦ g ≦ 12, 0 ≦ h ≦ 10, 1 ≦ f + g + h ≦
It is a number that satisfies each expression of 30. However, all the numbers in the above formula indicate atomic%), and the composition is substantially represented by an area ratio of fine crystal grains having an average grain size of, for example, 50 nm or less.
Those having 0% or more are mentioned. When such a fine crystal alloy is welded, it is possible to identify the welded portion because the crystal grains are larger than the average crystal grains other than the welded portion due to heat during welding.

The composition of the amorphous magnetic alloy ribbon or the Fe-based fine crystal alloy ribbon as described above is appropriately selected according to the intended use of the magnetic component formed by using the thin magnetic core of the present invention. For example, when used as a component such as a transformer, it is preferable to use a Co-based amorphous magnetic alloy or a Fe-based fine crystal alloy. Further, when applied to an inductance coil (saturable inductor) for filters, resonance, magamplifiers, etc., it is preferable to use a Co-based amorphous magnetic alloy having a high squareness ratio, and when applied to a choke coil, It is preferable to use an Fe-based amorphous magnetic alloy having excellent DC superposition characteristics.

The magnetic ribbon used in the present invention does not always exclude the use of a crystalline magnetic alloy ribbon such as permalloy or sendust, but in order to achieve a compact and thin magnetic component, It is preferable to use such an amorphous magnetic alloy ribbon or an Fe-based microcrystalline alloy ribbon (particularly, an amorphous magnetic alloy ribbon).

Such a magnetic ribbon has a thickness T of 30 μm.
The following is preferable. The width W is preferably 5 mm or less, and more preferably 2 mm or less. If the thickness T exceeds 30 μm, the iron loss of the magnetic ribbon itself becomes large, so that it is difficult to sufficiently obtain the effect of the present invention such as preventing the iron loss from rising by controlling the welded portion to a predetermined value or less. Further, if the thickness T exceeds 30 μm, the energy during welding must be increased, and from this point as well, the characteristics may be deteriorated.

The effect of fixing the magnetic ribbon end portion according to the present invention is as follows.
This is remarkable for a thin magnetic core using a magnetic ribbon having a width W of 5 mm or less. When the width W of the magnetic ribbon is 2 mm or less, a particularly remarkable effect is exhibited. This is because when the width W becomes smaller, the core is likely to come apart due to the stress during resin coating.

Furthermore, the present invention is particularly effective for thin magnetic cores having a ratio (D / W) of the outer diameter D of the core body to the width W of the magnetic ribbon of 3 or more. The present invention is particularly effective when using a core body having a large number of windings of the magnetic ribbon of 50 or more, further 100 or more.

Such a thin magnetic core having a large outer diameter to thin ribbon width having a D / W ratio of 3 or more, and a winding number of 50.
In the thin magnetic core having a core body with more than one winding, the core body is likely to disperse due to the stress when the resin coating is applied, so that the effect of the present invention can be more effectively obtained.

Further, the present invention is more effective when a magnetic ribbon having a high surface property is used. That is, when a magnetic ribbon having a high surface property is used, the end portion of the magnetic ribbon is easily peeled off. When the core body wound with such a magnetic ribbon is subjected to end welding over a plurality of layers of the magnetic ribbon, it becomes possible to enhance the shape maintaining ability of the core body.
The magnetic ribbon having a high surface property as used herein refers to a ribbon having a Ks value (= micro plate thickness / weight plate thickness) of 1.2 or less.

Examples of such welding of the magnetic ribbon include spot welding (current welding). If a similar fixing structure can be obtained, other welding methods such as laser welding can be applied. Moreover, it is preferable to carry out the terminal welding at a plurality of locations (for example, 2 to 20 locations) on the inner diameter side and the outer diameter side. Thereby, the fixed state of the magnetic ribbon end portion can be further stabilized.
At this time, the welding points may be concentrated near the ends or may be dispersed over the entire circumference.

The area of each weld is preferably 0.2 mm ² or less. By making the area of each welded portion equal to or smaller than such an area and dispersing a plurality of such areas, it is possible to suppress a local characteristic deterioration in the core and obtain a core having uniform characteristics.

In the present invention, the resin coating layer formed on the outer peripheral surface of the core body may be made of a thermosetting insulating resin such as a fluorine resin or an epoxy resin. In particular, it is preferable to use a fluorine resin represented by polytetrafluoroethylene (PTFE) for this resin coating layer. With this fluorine-based resin, the entire outer peripheral surface of the core body can be uniformly coated even when the thickness of the resin coating layer is reduced.

The method for producing the thin magnetic core of the present invention will be described below. First, a magnetic ribbon is wound around the surface of a winding core or the like, and when the number of turns is 2 to 5 layers, for example, spot welding is performed to end-weld the inner diameter side end portion. The specific conditions for terminal welding are as described above.

Next, starting from the end welding on the inner diameter side end, the magnetic ribbon is wound until the desired number of turns is obtained, and then the outer diameter side end is end welded by spot welding, for example. The number of turns of the magnetic ribbon is set appropriately according to the required characteristics of the intended magnetic component.

After that, the outer surface of the obtained core body is coated with a resin to form an outer package, whereby a desired thin magnetic core is obtained. The resin coating is performed, for example, by applying a powder resin, thermosetting, impregnating a resin liquid, thermosetting, or the like. The resin used for the resin coating is as described above.

The thin magnetic core having the toroidal shape as described above is provided with a winding on the resin coating layer, and a current path is provided so as to be substantially orthogonal to the magnetic path of the core body, whereby a transformer or a choke is provided. It can be used as a magnetic component such as a coil. Such a magnetic component of the present invention is a transformer for power supply or oscillation,
It can also be used as a pulse transformer for communication circuits. Also, depending on the case, it can be used as a choke coil or an inductance coil. Then, according to the magnetic component of the present invention, it is possible to achieve the reduction in size and thickness of the pulse transformer or the like based on the above-mentioned thin magnetic core.

[0051]

EXAMPLES Examples of the present invention will be described below. (Examples 1 to 6 and Comparative Example 1) As a magnetic ribbon, a width of 2 m
A Co-based amorphous alloy ribbon having a thickness of m and a thickness of 18 μm was used and wound into a toroidal shape having an outer diameter of 10 mm and an inner diameter of 5 mm. Then, the number of welds, the total area a of the welded portion, and the welding depth b were changed as shown in Table 1 to weld the magnetic ribbons on the inner diameter side and the outer diameter side to produce a thin magnetic core.

The shape of each thin magnetic core is the same,
The core volume V (volume of magnetic ribbon) was 88.3 mm ³ , and the core inner diameter side area S was 31.4 mm ² . Further, the maximum diameter R of the welded portion of each thin magnetic core was set to 0.2 mm or less.

In addition, as a comparative example, a thin magnetic core was produced by winding a magnetic ribbon made of Fe-based amorphous or fine crystal and then tape-fixing the outer diameter side end.

Next, the magnetic characteristics of these thin magnetic cores were measured. The iron loss was measured as the magnetic property, and the measurement conditions were 100 kHz and 200 mT. The results are shown in Table 1.

[Table 1]

As shown in Table 1, Examples 1 to 6 in which the magnetic ribbons on the inner diameter side and the outer diameter side were welded over a plurality of layers
It was confirmed that each of the thin magnetic cores of 1) had a high yield and was excellent in the fixing strength of the magnetic ribbon. In particular, the welding volume ratio ([(a × b) / V] × 100 (%)) is 5
It was confirmed that in Examples 1 to 3 in which the iron content was not more than%, the iron loss was suppressed to the same low level as that of the thin magnetic core produced by tape fixing.

(Examples 7 to 12, Comparative Examples 2 and 3) Fe-based amorphous, Co-based amorphous or fine crystals were used as the material for the magnetic ribbons, and they were wound into a toroidal shape.
Then, the number of welds, the total area a of the welded portion, and the welding depth b were changed as shown in Table 2 to weld the inner diameter side and the outer diameter side to produce a thin magnetic core. The maximum diameter R of the welded portion of each thin magnetic core was 0.2 mm or less.

In addition, as a comparative example, a thin magnetic core was produced by winding a magnetic ribbon made of Fe-based amorphous or fine crystal and then tape-fixing the end portion on the outer diameter side.

Next, the magnetic characteristics of these thin magnetic cores were measured. The iron loss was measured as the magnetic property, and the measurement conditions were 100 kHz and 200 mT. The results are shown in Tables 2 and 3.

[Table 2]

[Table 3]

As shown in Tables 2 and 3, in the thin magnetic cores of Examples 7 to 12 in which the magnetic ribbons on the inner diameter side and the outer diameter side were welded over a plurality of layers, the yield was high and the magnetic ribbons It was confirmed that the fixing strength was excellent regardless of the type. Further, as is clear from a comparison with a comparative example in which the same material and core width are used, it was confirmed that the thin magnetic core of the present invention suppressed the deterioration of the characteristics and significantly improved the yield. .

(Examples 13 to 16) Total area of welded part a =
3.92 mm ² , welding depth b = 0.1 mm, [(ax
b) / V] × 100 (%) = 4.44%, (a ₁ / S)
× 100 (%) = 6.3% was unified, and the maximum diameter R of the welded part was changed as shown in Table 4 while changing the number of welded parts to produce a thin magnetic core. The width of the magnetic ribbon is 2 mm,
A Co-based amorphous alloy ribbon having a thickness of 18 μm was used and wound into a toroidal shape having an outer diameter of 10 mm and an inner diameter of 5 mm.

Next, the iron loss of each thin magnetic core thus manufactured was measured. The iron loss is 100
It was performed at 200 mT at kHz.

[Table 4]

As shown in Table 4, the maximum diameter R is 0.2 mm.
It was confirmed that the properties exceeding 1.0 were deteriorated. It is considered that this is because the volume of the welded portion at one location becomes large and the influence is large. On the other hand, the maximum diameter R
No decrease in iron loss was confirmed for those having a thickness of 0.2 mm or less.

[0063]

As described above, according to the present invention, the shape of a wound body can be maintained with good reproducibility even when a thin wound body is used, which significantly increases the manufacturing yield and reliability. It is possible to improve. Further, in such a case, by defining the volume of the welded portion with respect to the volume of the core, it is possible to suppress the characteristic deterioration due to welding.

Furthermore, by using such a thin magnetic core, it is possible to provide a magnetic component that is compatible with miniaturization and thinning and has improved reliability and characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part (core body) of a thin magnetic core according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a thin magnetic core according to an embodiment of the present invention.

FIG. 3 is a sectional view schematically showing a welded state of the inner diameter side end portion of the thin magnetic core.

FIG. 4 is a plan view schematically showing a welded state of the inner diameter side end portion of the thin magnetic core.

[Explanation of symbols]

1 ... Core body 2 ... Thin magnetic core 3 ... Magnetic ribbon 4 ... Inner diameter side weld 5: Outer diameter side weld 6 ... Resin coating layer

Claims (10)

[Claims] 1. A thin core in which an insulating coating is applied to a core wound with a magnetic ribbon, wherein the inner-diameter ribbon and the outer-diameter ribbon are welded over a plurality of layers. Thin magnetic core. 2. The welding depth (b) is 30 μm or more, and the total area (a) of the welded portion with respect to the volume (V) of the core.
And the welding depth (b) as a percentage ([(a × b)
/ V] × 100 (%)) is 5% or less, The thin magnetic core according to claim 1. 3. The percentage ((a ₁ / S) × 100) of the total area (a ₁ ) of the inner diameter side welded portion to the area (S) of the core inner diameter side.
(%)) Is 15% or less.
The thin magnetic core described. 4. The thin magnetic core according to claim 1, wherein the area of each weld is 0.2 mm ² or less. 5. The thin magnetic core according to claim 1, wherein the total number of the welded portions is 2 to 20. 6. The magnetic ribbon is made of an amorphous alloy or a fine crystal alloy.
The thin magnetic core according to any one of 1. 7. The thin magnetic core according to claim 1, wherein the width of the core is 5 mm or less. 8. The thin magnetic core according to claim 1, wherein the insulating coating is made of a fluororesin. 9. The thin magnetic core according to claim 1, wherein the magnetic ribbon has a thickness of 30 μm or less. 10. A magnetic component comprising: the magnetic core according to claim 1; and a winding wire formed on the magnetic core.