JP2008112830A - Method of manufacturing magnetic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To divide a thin sheet type magnetic body into a plurality of pieces inexpensively while keeping the initial thickness of the thin sheet type magnetic body and suppressing the generation of a gap between the divided magnetic substances. <P>SOLUTION: The magnetic sheet 4 is manufactured by adhering the thin sheet type magnetic body 3 onto a sheet substrate 1 through a bonding layer 2. An external force is applied to the thin sheet type magnetic body 3 adhered to the sheet substrate 1 to divide the thin sheet type magnetic body 3 into a plurality of pieces while maintaining its adhesion state to the sheet substrate 1. The thin sheet type magnetic body 3 is divided into a plurality of magnetic substance strips 5, for example. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a magnetic sheet used for an inductor, a magnetic shield, and the like.

  With the reduction in size and weight of portable electronic devices typified by mobile phones, a non-contact charging method has attracted attention as a filling method for portable electronic devices and the like. The non-contact charging method is a method in which coils are provided in both the power receiving device and the power feeding device, and charging is performed using electromagnetic induction between these coils. The non-contact charging method has an advantage that the electrodes are not exposed and do not rust because the electrodes are not brought into contact with each other. In the contact-type charging method, connection plugs and chargers having different shapes are used for each device. However, the non-contact-type charging method that does not require an electrode has an advantage that the charger can be shared.

  When the non-contact charging method is applied to a portable electronic device or the like, a resonance circuit is applied to the power receiving device side (the electronic device side to be charged) in order to increase power receiving efficiency and the like. A resonance circuit configured by connecting L and C in series or in parallel has a maximum or minimum current flowing in the circuit at a specific resonance frequency. As an important characteristic for obtaining such sharpness (frequency selectivity) of the resonance circuit, there is a resonance Q value. The Q value is represented by Q = 2πfL / R, and can be increased by increasing the L value or reducing the loss (resistance R).

  By the way, when a resonance circuit is applied to a power receiving device of a portable electronic device, an inductor composed of a thin coil and a magnetic body (magnetic core) is required to be built in the portable electronic device. The magnetic material of the inductor is selected according to the transmission frequency. However, it is difficult to thin the ferrite that is frequently used at a frequency of several tens of kHz or more, and it is cracked due to impact or thermal strain due to rapid power application. It has the difficulty of being easy. On the other hand, silicon steel plates and permalloy, which are metal-based magnetic materials, have the disadvantages that loss is large unless the material is made thin, and the Q value, L value, and magnetic permeability are low. On the other hand, the L value can be improved by using a sheet-like magnetic body made of an amorphous alloy or a microcrystalline alloy.

In order to improve the characteristic of the resonance circuit (resonance impedance Z ₀ ), there is a method of increasing the Q value in addition to increasing the L value. However, in the high frequency range, the metal-based magnetic material increases in loss due to the influence of eddy current and decreases in Q value. As a countermeasure against this, a dust core obtained by solidifying a powdered magnetic material is known. The adaptive frequency of the dust core varies depending on the particle size of the magnetic material. Although the corresponding frequency band increases as the particle size of the magnetic material decreases, there is a problem that the magnetic permeability decreases. On the other hand, power devices such as switching power supplies are operated in the range of several tens of kHz to several hundreds of kHz from the viewpoints of efficiency, noise, manufacturing cost, and the like. In order to obtain an excellent resonance circuit at such a frequency, a method of increasing the Q value by dividing the magnetic sheet is effective.

Further, when the magnetic sheet is used as a magnetic shield or the like, it is effective because the eddy current is suppressed by dividing the magnetic sheet. For example, Patent Document 1 describes a magnetic sheet in which an assembly in which a plurality of magnetic material pieces are laid is held by a sheet base material. Here, a magnetic sheet is used as the magnetic body of the RFID antenna. As described above, when a plurality of magnetic substance pieces are laid, a certain amount of gaps are inevitably generated between adjacent magnetic substance pieces, and the characteristics of the magnetic sheet are likely to deteriorate. In addition, when the magnetic material pieces are arranged in an overlapping manner, electrical conduction is generated and the characteristics are deteriorated, and the thickness of the magnetic material sheet is also increased. The method of laying a plurality of magnetic substance pieces inevitably increases the manufacturing cost.
JP 2006-174223 A

  The object of the present invention is to enable the thin plate-like magnetic body to be divided at a low cost while maintaining the original thickness of the thin plate-like magnetic body (magnetic sheet), and to generate a gap between the divided magnetic bodies. It is in providing the manufacturing method of the magnetic sheet which suppressed the.

  The method for producing a magnetic sheet according to an aspect of the present invention includes a step of forming a magnetic sheet by adhering a thin plate-like magnetic body on a sheet base material via an adhesive layer, and using the thin plate-like magnetic body as the sheet base material. And a step of dividing into a plurality of parts by an external force while maintaining the bonded state.

  According to the method for manufacturing a magnetic sheet according to the aspect of the present invention, it is possible to divide the thin plate-like magnetic body into a plurality of pieces at a low cost while maintaining the original thickness of the thin-plate-like magnetic body, and to divide the magnetic material divided thereon. It becomes possible to suppress generation | occurrence | production of the clearance gap between bodies. Therefore, it is possible to provide a magnetic sheet having excellent characteristics and reliability at a low cost.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 are diagrams showing a manufacturing process of a magnetic sheet according to an embodiment of the present invention. First, as shown in FIG. 1A and FIG. 2A, a sheet base material 1 having an adhesive layer 2 is prepared, and a thin plate-like magnetic body 3 is formed on the sheet base material 1 with the adhesive layer 2 interposed therebetween. The magnetic sheet 4 is formed by bonding. As long as the sheet base material 1 has flexibility and thickness that do not hinder the division of the thin plate-like magnetic body 3, resin films made of various insulating resin materials can be used.

  The sheet substrate 1 is made of, for example, a polyethylene terephthalate (PET) film having a thickness of 1 μm to 100 μm, a polyimide film, a polyester film, a polyphenylene sulfide (PPS) film, a polypropylene (PP) film, and a polytetrafluoroethylene (PTFE). Such a resin film such as a fluororesin film is suitable.

  Although depending on the resin material, when the thickness of the resin film exceeds 100 μm, the use of the sheet base material 1 may hinder the division of the thin plate-like magnetic body 3. On the other hand, when the thickness of the sheet substrate 1 is less than 1 μm, the function of the thin plate-like magnetic body 3 after the division as a support may be lowered. An adhesive made of acrylic resin, silicone resin, butadiene resin, hot melt, or the like can be applied to the adhesive layer 2.

  By applying an adhesive on the surface of the resin film as described above, or by using a resin film with an adhesive in advance, the sheet substrate 1 having the adhesive layer 2 is obtained. A thin plate-like magnetic body 3 is bonded onto such a sheet substrate 1 via an adhesive layer 2. Various magnetic sheets (films) can be used as the thin plate-like magnetic body 3, but it is preferable to use a magnetic alloy such as an amorphous alloy, a microcrystalline alloy, or permalloy. Any of these magnetic alloys can be thinned (rolled thin) by a roll quenching method, a rolling method, or the like, and can be divided by applying an external force in a state of being bonded onto the sheet substrate 1. it can.

  Among the magnetic alloys described above, it is preferable to form the thin plate-like magnetic body 3 with an amorphous alloy or a microcrystalline alloy. As described above, according to the thin plate-like magnetic body 3 made of an amorphous alloy or a microcrystalline alloy, the L value of an inductor using the same can be improved. Table 1 shows the L value and Q value of the inductor based on the magnetic material. Here, a copper wire having a diameter of 0.5 mm is wound into a flat plate to produce a coil having an outer diameter of 30 mm and a thickness of about 1 mm, and sheets (30 × 40 mm) made of various magnetic materials are attached to the coil. The L value and Q value at 500 kHz were measured. These values are shown in Table 1.

As is apparent from Table 1, when an amorphous alloy sheet or a microcrystalline alloy sheet is used, the L value is improved by 30 to 40%, whereas silicon steel sheets and permalloy have large eddy current loss. Both L value and Q value are decreasing. Further, it can be seen that ferrite cannot be reduced in thickness, and that the electromagnetic wave absorbing sheet has a small effect of improving the L value. The composition of Co-based amorphous 1 is Co ₇₀ Fe _4.5 Ni _2.5 Si ₁₃ B ₁₀ , the composition of Co-based amorphous 2 is Co ₆₈ Fe _4.5 Cr _2.5 Si ₁₅ B ₁₀ , the composition of Fe-based amorphous is Fe ₇₈ Si ₁₄ B ₈ , The composition of the crystal alloy is Fe ₇₄ Nb ₂ Cu ₂ Si ₈ B ₁₄ .

The amorphous alloy applied to the thin plate-like magnetic body 3 may be either a Co-based amorphous alloy or a Fe-based amorphous alloy, but a Co-based amorphous alloy is particularly suitable. Specific examples of amorphous alloys include
General formula: (T _1-a M _a ) _100-b X _b (1)
(Wherein T is at least one element selected from Co and Fe, M is Ni, Mn, Cr, Ti, Zr, Hf, Mo, V, Nb, W, Ta, Cu, Ru, Rh, At least one element selected from Pd, Os, Ir, Pt, Re and Sn; X represents at least one element selected from B, Si, C and P; a and b are 0 ≦ a ≦ 0 .3, 10 ≦ b ≦ 35 at%)
What has a composition represented by these is mentioned.

  In the above equation (1), the element T adjusts the composition ratio according to required magnetic properties such as magnetic flux density, magnetostriction value, iron loss and the like. The element M is an element added for thermal stability, corrosion resistance, control of the crystallization temperature, and the like. The amount of M element added is preferably 0.3 or less as the value of a. If the amount of M element added is too large, the amount of T element is relatively reduced, so that the magnetic properties of the amorphous magnetic alloy are deteriorated. In practice, the value of a indicating the amount of M element added is preferably 0.01 or more. The value of a is more preferably 0.15 or less.

  Element X is an essential element for obtaining an amorphous alloy. In particular, B (boron) is an effective element for amorphizing a magnetic alloy. Si (silicon) is an element that assists the formation of an amorphous phase and is effective in raising the crystallization temperature. If the content of the X element is too large, the magnetic permeability is lowered and brittleness occurs. On the other hand, if the content is too small, it becomes difficult to form an amorphous material. For this reason, the content of the X element is preferably in the range of 10 to 35 at%. The X element content is more preferably in the range of 15 to 25 at%.

As a specific example of a microcrystalline alloy,
General _{formula: Fe 100-cdefgh A c D} d E e Si f B g Z h ... (2)
(Wherein A is at least one element selected from Cu and Au, D is at least one element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ni, Co and rare earth elements) The seed element, E represents at least one element selected from Mn, Al, Ga, Ge, In, Sn and platinum group elements, Z represents at least one element selected from C, N and P; c, d, e, f, g, and h are 0.01 ≦ c ≦ 8 at%, 0.01 ≦ d ≦ 10 at%, 0 ≦ e ≦ 10 at%, 10 ≦ f ≦ 25 at%, 3 ≦ g ≦ 12 at%. 15 ≦ f + g + h ≦ 35 at%)
And 20% or more of the structure by area ratio is made of fine crystal grains having a particle size of 50 nm or less.

  In the above formula (2), the element A is an element that enhances corrosion resistance, prevents coarsening of crystal grains, and improves magnetic properties such as iron loss and magnetic permeability. If the content of the element A is too small, the effect of suppressing the coarsening of crystal grains cannot be obtained sufficiently. Conversely, if the content of the element A is too large, the magnetic properties deteriorate. Therefore, the content of element A is preferably in the range of 0.01 to 8 at%. The element D is an element effective for making the crystal grain size uniform and reducing magnetostriction. The content of element D is preferably in the range of 0.01 to 10 at%.

  Element E is an element effective for improving soft magnetic properties and corrosion resistance. The content of element E is preferably 10 at% or less. Si and B are elements that assist the amorphization of the alloy during the production of the ribbon. The Si content is preferably in the range of 10 to 25 at%, and the B content is preferably in the range of 3 to 12 at%. In addition, Z element may be included as an amorphization auxiliary element other than Si and B. In that case, the total content of Si, B and Z elements is preferably in the range of 15 to 35 at%. In particular, the microcrystalline structure preferably has a form in which crystal grains having a grain size of 5 to 30 nm are present in the alloy in an area ratio of 50 to 90%.

  The amorphous alloy ribbon used as the thin plate-like magnetic body 3 can be produced by, for example, a roll quenching method (a molten metal quenching method). Specifically, it is produced by rapidly cooling an alloy material adjusted to a predetermined composition ratio from a molten state. The microcrystalline alloy ribbon is prepared by, for example, an amorphous alloy ribbon by a liquid quenching method, and then subjected to heat treatment at a temperature in the range of −50 to + 120 ° C. for 1 minute to 5 hours with respect to the crystallization temperature. It can be obtained by a method of precipitating fine crystal grains. Alternatively, the microcrystalline alloy ribbon can also be obtained by a method of directly depositing microcrystalline grains by controlling the quenching rate of the liquid quenching method. Permalloy can be thinned by forging, rolling, etc. using a molten ingot or a sintered ingot.

  The thin plate-like magnetic body 3 made of an amorphous alloy or a microcrystalline alloy is preferably subjected to a heat treatment before the dividing step. Amorphous alloys and microcrystalline alloys become brittle when subjected to heat treatment, and therefore can be easily split (divided into a plurality of parts) when an external force is applied in a splitting step described in detail later. The heat treatment is preferably performed before the thin plate-like magnetic body 3 is bonded to the sheet substrate 1. The thin plate-like magnetic body 3 made of an amorphous alloy is preferably subjected to heat treatment at a temperature of 300 to 500 ° C. for 0.1 to 10 hours in an air atmosphere or an atmosphere such as nitrogen or argon. The thin plate-like magnetic body 3 made of a microcrystalline alloy is preferably subjected to heat treatment at a temperature of 550 to 700 ° C. for 0.1 to 10 hours in an atmosphere of nitrogen or argon.

  The thickness of the thin plate-like magnetic body 3 made of the magnetic alloy as described above is preferably in the range of 5 μm to 30 μm. If the thickness of the thin plate-like magnetic body 3 exceeds 30 μm, it becomes difficult to make it amorphous at the time of material preparation, and a thin plate made of an amorphous alloy or a microcrystalline alloy subjected to heat treatment due to generation of partial crystals or increase in internal strain. Even in the shape of the magnetic body 3, non-uniform cracking is likely to occur, and it is difficult to divide into a desired shape. On the other hand, if the thickness of the thin plate-like magnetic body 3 is less than 5 μm, the strength of the material itself is weakened, and non-uniform cracking is likely to occur. The thickness of the thin plate-like magnetic body 3 is more preferably in the range of 10 μm or more and 20 μm or less.

  Next, an external force is applied to the thin plate-shaped magnetic body 3 bonded to the sheet base material 1 to divide the thin plate-shaped magnetic body 3 into a plurality while maintaining the state bonded to the sheet base material 1. Specifically, as shown in FIGS. 1B and 2B, the thin plate-like magnetic body 3 is divided into a plurality of magnetic body pieces 5 by applying an external force. Thus, by dividing the thin plate-like magnetic body 3 into a plurality of magnetic body pieces 5, the Q value can be improved when the magnetic sheet 4 is used as a magnetic body for an inductor, for example. Further, when the magnetic sheet 4 is used as a magnetic body for magnetic shielding, for example, the current path of the thin plate-like magnetic body 3 can be divided to reduce eddy current loss.

  The dividing step of the thin plate-like magnetic body 3 is performed by, for example, directly bending the magnetic sheet 4 and breaking the thin plate-like magnetic body 3. In addition to such a method, for example, a method of bending the magnetic sheet 4 through a rolling roll or pressing and splitting it with a mold can be applied. Furthermore, a method of dividing the thin plate-like magnetic body 3 into a predetermined shape by providing a predetermined uneven pattern on the mold or roll is also applicable. Depending on the material conditions of the sheet base material 1 and the thin plate-like magnetic body 3, a material such as rubber that is easily deformed may be used for one of the pair of molds and rolls. In the case of using a rolling roll, it is effective to provide a difference in peripheral speed between the pair of rolls and to apply a shearing force as well as a simple pressure.

  In order to prevent scattering of the magnetic piece 5 in the step of dividing the thin plate-like magnetic body 3, a protective film with an adhesive or the like can be attached as a cover layer on the thin plate-like magnetic body 3. In addition, the protective film with an adhesive may be attached on the thin plate-like magnetic body 3 after the dividing step in order to prevent the magnetic piece 5 from dropping off during the post-process or during use. In actual use, it is also possible to peel off the sheet base material 1 and the protective film to expose the adhesive layer, and use this adhesive layer to affix it to a coil, various parts, an equipment casing or the like.

  The above-described dividing step not only can divide the thin plate-like magnetic body 3 at a low cost, but also is performed while maintaining the state where the thin-plate-like magnetic body 3 is adhered to the sheet base material 1. The thin plate-like magnetic body 3 can be easily divided without dropping the body piece 5 and maintaining the original thickness of the thin-plate-like magnetic body 3. Therefore, it is possible to obtain the magnetic sheet 4 having the thin plate-like magnetic bodies 3 (the plurality of magnetic body pieces 5) efficiently divided into a plurality of pieces at low cost without deteriorating characteristics and reliability.

  Furthermore, according to the division | segmentation process mentioned above, the thin plate-shaped magnetic body 3 is electrically divided, without producing almost a physical space | gap between the magnetic body pieces 5 (thin plate-shaped magnetic body 3 divided | segmented into plurality). Can do. Specifically, the area ratio of the gap portion (gap between the magnetic pieces 5) to the apparent occupied area of the thin plate-like magnetic body 3 divided into a plurality can be set to 5% or less. The area ratio of the gap is more preferably 3% or less. Here, the apparent occupied area of the thin plate-like magnetic body 3 divided into a plurality corresponds to the area of the original thin-plate-like magnetic body 3. For example, in FIG. The area based on the outermost shape of the aggregate | assembly of 5 is shown.

  In this way, by suppressing the generation of gaps between the magnetic pieces 5 as much as possible (the area ratio of the gaps is 5% or less), it is possible to suppress the deterioration of the magnetic properties of the thin plate-like magnetic body 3, and It becomes possible to suppress noise, magnetic flux leakage, and the like due to the gap (gap). For example, in the conventional method of laying magnetic pieces, it is unavoidable that gaps are generated, for example, in order to prevent the magnetic pieces from overlapping with each other, thereby increasing the area ratio of the gaps (voids). Furthermore, when the magnetic pieces are aligned with a minimum gap, the manufacturing cost is greatly increased. Even in this case, the area ratio of the gap (gap) cannot be sufficiently reduced.

The number of divisions of the thin plate-like magnetic body 3 is not particularly limited, and is appropriately set according to the use and required characteristics of the magnetic sheet 4. For example, when the 30 × 40 mm thin plate-like magnetic body 3 is divided into 64 parts, the average shape of the magnetic piece 5 is about 3.7 × 5 mm, and when divided into 256 parts, it is about 1.8 × 2.5 mm and 1024 parts. In this case, it becomes about 0.9 × 1.2 mm. The area of each magnetic piece 5 is preferably in the range of 0.01 mm ^{2 to} 25 mm ² . Further, by orienting the shape of the magnetic piece as a rectangle, it is possible to improve magnetic characteristics such as magnetic permeability in a specific direction. In this case, it is effective to set the aspect ratio (long side (length) / short side (width)) of the magnetic piece to 2 or more.

When the area of each magnetic piece 5 formed by dividing the thin plate-like magnetic body 3 exceeds 25 mm ² , the effect of dividing the thin plate-like magnetic body 3 into a plurality of parts (Q value improving effect, eddy current loss reducing effect, etc.) May not be sufficient. On the other hand, in order to make the area of the magnetic piece 5 less than 0.01 mm ^{2, the} number of divisions becomes too large, leading to an increase in the cost of the division process and an increase in the area ratio of the gaps. The area of the magnetic piece 5 is more preferably in the range of 0.1 to 10 mm ² .

  However, the divided shape of the thin plate-like magnetic body 3 is not limited to dividing the whole into the magnetic piece 5, and a part of the thin plate-like magnetic body 3 may be the magnetic piece 5. The magnetic piece 5 can be formed on at least a part of the thin plate-like magnetic body 3. For example, as shown in FIG. 3, the vicinity of the center in the vertical and horizontal directions of the thin plate-like magnetic body 3 may be divided into a plurality of pieces, and the magnetic piece 5 may be formed only near the center of the thin plate-like magnetic body 3. In addition, the code | symbol 6 in FIG. 3 has shown the planar type coil (spiral coil) which comprises an inductor.

  That is, when the magnetic sheet 4 is used as a magnetic body for an inductor, the thin plate-like magnetic body is such that the small-area magnetic body piece 5 is positioned at least in a portion corresponding to the central portion of the coil 6 (a portion through which magnetic flux passes). 3 can be divided by external force. Even with the magnetic sheet 4 having such a divided structure of the thin plate-like magnetic body 3, an effect of improving the Q value of the inductor can be obtained. The magnetic sheet 4 having such a structure is also effective when the magnetic sheet 4 as the inductor magnetic body also serves as a magnetic shield function.

  Further, the thin plate-like magnetic body 3 is not limited to being divided into a lattice shape, and may be divided in an oblique direction, or a combination of the lattice-like division and the oblique direction division may be combined. The shape of the magnetic sheet 4 is not limited to a rectangular sheet shape, and can be processed into various sheet shapes such as a round shape and an E shape by punching or the like. Thus, the magnetic sheet 4 having various shapes, that is, the magnetic sheet 4 having various shapes having the thin plate-like magnetic body 3 divided into various shapes can be obtained.

  The magnetic sheet 4 obtained by the manufacturing method of the embodiment described above, that is, the magnetic sheet 4 having the thin plate-like magnetic body 3 divided into, for example, a magnetic body for an inductor or a magnetic body for a magnetic shield (including a noise countermeasure sheet). Used as In particular, it is suitable for a sheet-like magnetic body (thin magnetic body) used in a frequency band of 100 kHz or higher. That is, the effect of improving the Q value, the effect of reducing eddy current loss, and the like based on the thin plate-like magnetic body 3 divided into a plurality of parts are better exhibited in the frequency band of 100 kHz or more. Therefore, the magnetic sheet 4 is suitable as a magnetic body for an inductor or a magnetic body for a magnetic shield used in a frequency band of 100 kHz or higher.

  A specific use of the magnetic sheet 4 is, for example, an inductor magnetic body in a resonance circuit including an inductor having a coil and a magnetic body and a capacitor. The coil constituting the inductor is preferably a planar coil such as a spiral coil. Such an inductor having a magnetic body (magnetic sheet 4) and a coil is suitably used for a resonance circuit or the like provided on the non-contact charging type power receiving device side (for example, the filled electronic device side). The magnetic body (magnetic sheet 4) constituting the inductor of the resonance circuit also functions as a magnetic shield.

  The magnetic sheet 4 is also effective as a magnetic shield provided on the non-contact charging type power receiving device side (for example, the filled electronic device side). Such a magnetic shield (magnetic sheet 4) includes, for example, a secondary battery and a spiral coil (secondary coil), a rectifier and a spiral coil, an electronic device and a spiral coil, a spiral coil and a circuit board. Are arranged in at least one place selected from the above.

  By arranging the magnetic shield (magnetic sheet 4) on the non-contact charging type power receiving device side, it is possible to suppress the generation of eddy currents caused by the magnetic flux interlinked with the spiral coil during charging. Therefore, it is possible to prevent the problem of heat generation due to the generation of eddy currents and the generation of noise. In particular, when large power transmission and rapid charging are performed in response to the increase in capacity of portable electronic devices such as cellular phones, the rechargeable battery is a metal body, and there is a problem that eddy current is generated by magnetic flux and heat is generated. In that case, it is effective to arrange a magnetic sheet between the coil and the rechargeable battery.

  Next, specific examples of the present invention and evaluation results thereof will be described.

(Example 1)
First, an acrylic adhesive was applied to a surface of a PET film having a thickness of 25 μm with a thickness of 10 μm. A Co-based amorphous alloy sheet having a thickness of 18 μm was bonded onto this PET film via an adhesive layer. The composition of the Co-based amorphous alloy sheet was Co ₇₀ Fe _4.5 Cr _1.5 Si ₁₀ B ₁₄ and heat-treated in advance at 430 ° C. × 20 minutes. Such a magnetic sheet was sequentially bent at a predetermined interval to divide the Co-based amorphous alloy sheet, thereby producing a magnetic sheet having a plurality of thin plate-like magnetic bodies.

  By adjusting the bending interval of the Co-based amorphous alloy sheet, magnetic sheets with various changes in the number of divisions of the Co-based amorphous alloy sheet were produced. Each of these magnetic sheets was attached to a planar coil (a copper wire having a diameter of 0.5 mm was wound in a flat plate shape, an outer diameter of 30 mm, a thickness of about 1 mm), and an L value and a Q value at 500 kHz were measured. The result is shown in FIG. As can be seen from FIG. 4, the Q value improves as the number of divisions of the magnetic sheet (here, Co-based amorphous alloy sheet) increases.

  FIG. 6 shows an enlarged photograph of the fine structure of the divided magnetic sheet. FIG. 7 is an enlarged photograph showing the main part of FIG. 6 further enlarged. Although the shapes of the magnetic pieces are slightly different from each other, the boundary interval is 2 to 3 μm, and it can be seen that the magnetic pieces are closely combined as in a jigsaw puzzle. It can be seen that this magnetic sheet (for example, a magnetic sheet for magnetic shielding) has a structure in which the intervals between the magnetic pieces are 10 μm or less, and the magnetic pieces are densely arranged.

  In addition, a magnetic sheet in which the Co-based amorphous alloy sheet is not divided, a magnetic sheet in which the Co-based amorphous alloy sheet is divided into 16 parts, and a magnetic sheet in which the Co-based amorphous alloy sheet is divided into 1024 parts are prepared, and these are attached to the planar coil. In addition, the frequency dependence of the Q value was measured. The result is shown in FIG. As is clear from FIG. 5, it can be seen that the effect of improving the Q value by dividing the magnetic material sheet (here, Co-based amorphous alloy sheet) is more satisfactorily exhibited in a frequency band of 100 kHz or more.

(Example 2)
A heat-treated microcrystalline alloy sheet was bonded onto a 25 μm thick polyimide film with an adhesive to produce a magnetic sheet. The composition of the microcrystalline alloy sheet was Fe ₇₃ Cu ₂ Nb _2.5 Si _12.5 B ₁₀ and the shape was 20 × 40 mm. The magnetic sheet was bent 9 times in the vertical and horizontal directions to divide the microcrystalline alloy sheet into magnetic pieces (100 pieces) having a shape of approximately 2 × 4 mm. The area ratio of the gaps in this magnetic sheet was 0.1%.

  Similarly, the magnetic sheet was bent 19 times vertically and horizontally, and the microcrystalline alloy sheet was divided into magnetic body pieces (400 pieces) having a shape of approximately 1 × 2 mm. The area ratio of the gaps in this magnetic sheet was 0.3%. When the Q value (500 kHz) when these magnetic sheets were used was measured in the same manner as in Example 1, the Q value of the magnetic sheet having 100 magnetic pieces was 13,400 magnetic pieces having magnetic pieces. The Q value of the sheet was 15.

  On the other hand, according to the conventional laying method, the material is first cut into 2 × 4 mm and aligned to prevent deformation during the heat treatment, and then the heat treatment is performed. Although 2 × 4 mm pieces of magnetic material are arranged on the adhesive sheet, a large cost is required to align small magnetic pieces while maintaining a minute gap. Further, for example, even if a device for arranging magnetic substance pieces with an accuracy of 0.1 mm is introduced, the finished size is 21.9 × 41.9 mm, and the area ratio of the gap is 6.4% (the occupation ratio of the magnetic substance) Is 93.6%).

  Further, when the individual piece shape is 1 × 2 mm (400 divisions), the area ratio of the gap portion is 12.8% (the occupation ratio of the magnetic material is 87.2%), and the magnetic characteristics are deteriorated. Become. The conventional laying method not only makes it difficult to produce a split-type sheet, but also reduces the area occupancy of the magnetic material, leading to a decrease in practicality.

(Example 3)
In the same manner as in Example 1, a Co-based amorphous alloy sheet having a thickness of 18 μm and a planar shape of 30 × 40 mm was bonded onto a PET film having a thickness of 25 μm via an adhesive layer. The vicinity of the center of the Co-based amorphous alloy sheet was divided by bending it three times vertically and horizontally with a width of 2.5 mm. In this way, as shown in FIG. 3, a magnetic piece having a shape of approximately 2.5 × 2.5 mm was formed only near the center of the Co-based amorphous alloy sheet. The Q value when this magnetic sheet was used was measured in the same manner as in Example 1. The results are shown in Table 2. Table 2 also shows the Q value when the Co-based amorphous alloy sheet is not divided (comparative example).

  As is apparent from Table 2, even when the magnetic piece is formed in the vicinity of the center of the magnetic sheet (here, the Co-based amorphous alloy sheet), that is, only in the portion corresponding to the center of the coil, the frequency band of 100 kHz or more ( In particular, the Q value at 200 kHz or more can be improved. Thus, when using a magnetic sheet as a magnetic body for inductors, you may form a magnetic body piece only in the part corresponded to the center part of a coil.

It is a top view which shows the manufacturing process of the magnetic sheet by embodiment of this invention. It is a figure which shows the manufacturing process of the magnetic sheet shown in FIG. It is sectional drawing which shows the modification of the division structure of a thin-plate-like magnetic body in the manufacturing process of embodiment of this invention. It is a figure which shows the example of a measurement of L value and Q value at the time of changing the division | segmentation number of a thin-plate-like magnetic body (magnetic material sheet). It is a figure which shows the example of a measurement of the frequency dependence of Q value at the time of dividing | segmenting a thin-plate-like magnetic body (magnetic material sheet). 4 is an enlarged photograph showing a microstructure of a divided part of a magnetic sheet according to Example 1. It is the photograph which expands and shows the principal part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sheet base material, 2 ... Adhesion layer, 3 ... Thin plate-like magnetic body, 4 ... Magnetic sheet, 5 ... Magnetic body piece.

Claims (10)

A step of forming a magnetic sheet by adhering a thin plate-like magnetic body on a sheet substrate via an adhesive layer;
A step of dividing the thin plate-like magnetic body into a plurality by an external force while maintaining the state of being adhered to the sheet base material. In the manufacturing method of the magnetic sheet of Claim 1,
A method for producing a magnetic sheet, wherein the thin plate-like magnetic body is divided into a plurality of pieces so that at least a part of the thin-plate-like magnetic body is a magnetic piece having an area of 0.01 mm ² or more and 25 mm ² or less. . In the manufacturing method of the magnetic sheet of Claim 1 or Claim 2,
The method for producing a magnetic sheet, wherein the thin plate-like magnetic body is made of an amorphous alloy or a microcrystalline alloy. In the manufacturing method of the magnetic sheet of Claim 3,
A method for producing a magnetic sheet, comprising a step of subjecting the thin plate-like magnetic body made of the amorphous alloy or the microcrystalline alloy to a heat treatment before the dividing step. In the manufacturing method of the magnetic sheet according to any one of claims 1 to 4,
The method for producing a magnetic sheet, wherein the thin plate-like magnetic body has a thickness in the range of 5 μm to 30 μm. In the manufacturing method of the magnetic sheet of any one of Claims 1 thru | or 5,
A method for producing a magnetic sheet, wherein an area ratio of a gap portion to an apparent occupied area of the plurality of thin plate-like magnetic bodies is 5% or less. In the manufacturing method of the magnetic sheet according to any one of claims 1 to 6,
The method for producing a magnetic sheet, wherein the magnetic sheet is used in a frequency band of 100 kHz or more. In the manufacturing method of the magnetic sheet according to any one of claims 1 to 7,
The method of manufacturing a magnetic sheet, wherein the magnetic sheet is an inductor magnetic body or a magnetic shield magnetic body. In the manufacturing method of the magnetic sheet of Claim 8,
The magnetic sheet as the magnetic body for an inductor is used for a resonance circuit including an inductor and a capacitor having a coil and a magnetic body, and a method for producing a magnetic sheet. In the manufacturing method of the magnetic sheet according to claim 9,
The magnetic sheet as the inductor magnetic body is divided so that a magnetic piece having an area of 0.01 mm ² or more and 25 mm ² or less is located at least in a portion corresponding to a central portion of the coil. A method for manufacturing a magnetic sheet.