Body with magnetic film attached and manufacturing method thereof

Abstract

A fabrication method for fabricating a magnetic film provided body includes preparing a base body and forming a magnetic film on the base body. The magnetic film includes organic film(s) and ferrite film(s) alternately layered. The formation of the magnetic film alternately includes forming a ferrite film through a ferrite plating method, the ferrite film having a thickness of 20 m or less and forming an organic film having a thickness of 0.1 m to 20 m, both inclusive, and a ratio t/E of 0.025 m/GPa or more, where t indicates the thickness of the organic film while E indicates Young's modulus of the organic film.

Claims

1. A fabrication method of a magnetic film provided body comprising: preparing a base body; and forming a magnetic film on the base body, the magnetic film comprising a first ferrite film, an organic film, and a second ferrite film, with the organic film layered between the first and second ferrite films, wherein the formation of the magnetic film comprises: forming the first ferrite film through a ferrite plating method, the first ferrite film having a thickness of 20 m or less; forming the organic film, the organic film having a thickness of 0.1 m to 20 m, and the organic film having a ratio t/E of 0.025 m/GPa or more, where t indicates the thickness of the organic film, and E indicates Young's modulus of the organic film; and forming the second ferrite film through the ferrite plating method, the second ferrite film having a thickness of 20 m or less.

2. The fabrication method as recited in claim 1, wherein the formation of the magnetic film further comprises: forming another organic film directly on the base body, wherein the first ferrite film is formed on said another organic film.

3. The fabrication method as recited in claim 1, wherein the formation of the magnetic film comprises forming the first ferrite film directly on the base body.

4. A fabrication method of a magnetic film provided body comprising: preparing a base body; and forming a magnetic film on the base body, the magnetic film comprising at least two organic films and at least two ferrite films alternately layered, wherein the formation of the magnetic film comprises: forming a first organic film directly on the base body; forming a first ferrite film through a ferrite plating method directly on the first organic film; forming a second organic film directly on the first ferrite film; and forming a second ferrite film through the ferrite plating method directly on the second organic film, wherein each of the first and second organic films has a thickness of 0.1 m to 20 m, and each of the first and second organic films has a ratio t/E of 0.025 m/GPa or more, where t indicates the thickness of the organic film, and E indicates Young's modulus of the organic film, and wherein each of the first and second ferrite films has a thickness of 20 m or less.

5. The fabrication method as recited in claim 4, wherein the first and second organic films are polyimide films.

6. The fabrication method as recited in claim 5, wherein the first and second organic films have a Young's modulus of 4 GPa.

7. The fabrication method as recited in claim 5, wherein the first and second organic films have a Young's modulus of 3 GPa.

8. A fabrication method of a magnetic film provided body comprising: preparing a base body; and forming a magnetic film on the base body, the magnetic film comprising an organic film and two ferrite films alternately layered, with the organic film between the two ferrite films, wherein the formation of the magnetic film comprises: forming a first ferrite film through a ferrite plating method directly on the base body; forming an organic film directly on the first ferrite film; and forming a second ferrite film through the ferrite plating method directly on the organic film, wherein the organic film has a thickness of 0.1 m to 20 m, both inclusive, and the organic film has a ratio t/E of 0.025 m/GPa or more, where t indicates the thickness of the organic film, and E indicates Young's modulus of the organic film, and wherein each of the first and second ferrite films has a thickness of 20 m or less.

9. The fabrication method as recited in claim 8, wherein the base body is made of an organic material.

10. The fabrication method as recited in claim 9, wherein the base body has a ratio t/E of 0.025 m/GPa or more, where t indicates a thickness of the base body, and E indicates Young's modulus of the base body.

11. The fabrication method as recited in claim 8, wherein the organic film is a polyimide film.

12. The fabrication method as recited in claim 8, wherein the organic film comprises epoxy resin and Fe.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross-sectional view schematically showing a magnetic film provided body according to an embodiment of the present invention.

(2) FIG. 2 is a view schematically showing a film formation apparatus which is used in a fabrication method of the magnetic provided body according to an embodiment of the present invention.

(3) FIG. 3 is a cross-sectional view schematically showing a variation example of the magnetic film provided body of FIG. 1.

(4) FIG. 4 is a view schematically showing an examination method of adhesive strength.

(5) FIG. 5 is a view schematically showing an examination method of flexibility.

DESCRIPTION OF NUMERALS

(6) 1 Reaction Solution Nozzle 2 Oxidizing Solution Nozzle 3 Base body 4 Turn Table 5, 5a Magnetic Film 6 Organic Film 7 Ferrite Film 10, 10a Magnetic Film Provided Body 20 Stage 22 Double-sided Tape 24 PET Film 30 Mount Plate 32 Vibration Plate R Bending Radius

BEST MODE FOR CARRYING OUT INVENTION

(7) As shown in FIG. 1, a magnetic film provided body 10 according to an embodiment of the present invention comprises a base body 3 and a magnetic film 5 provided on the base body 3. The magnetic film 3 comprises organic films 6 and ferrite films 7 alternately layered. An adhesive strength between the organic film 6 and the ferrite film 7 is 0.1 kN/m or more. Especially, in the magnetic film provided body 10 of the present embodiment, it is not the ferrite film 7 but the organic film 6 which is formed directly on the base body 3. An adhesive strength between the directly-formed organic film 6 and the base body 3 is 0.1 kN/m or more, too. In the present embodiment, the adhesive strength between the base body 3 and the organic film 6 as well as each adhesive strength between the organic film 6 and the ferrite film 7 is 0.1 kN/m or more so that an exfoliation problem may not occur. The adhesive strength in the embodiment is examined by the exfoliation test in conformance with JIS C5016 (test methods for flexible printed wiring boards).

(8) In order that the adhesive strength between the layers to be 0.1 kN/m or more, in the embodiment, optimum conditions of a thickness of the ferrite film, a thickness of the organic film, and a ratio t/E are defined as follows, where t indicates the thickness of the organic film 6, and E indicates Young's modulus of the organic film 6. First, the ratio of t/E of each organic film 6 is defined to be 0.025 m/GPa or more. By the use of the organic film 6 which satisfies the condition, a sufficient stress relaxation effect can be obtained. In addition, the thickness of each ferrite film 7 is defined to be 20 m or less, and the organic film 6 which has a thickness of 0.1 m or more is interposed between the ferrite films 7. Therefore, the above-mentioned adhesive strength of 0.1 kN/m or more can be obtained. In consideration of productivity, the ratio of t/E is preferred to be 1000 m/GPa or less. A total thickness of the ferrite films 7 included in the magnetic film 5 is defined to be 1 m or more so that the magnetic film 5 which produces a high electromagnetic effect can be obtained. The thickness of each organic film 6 is defined to be 20 m or less so that a device which uses the magnetic film provided body of the embodiment can be miniaturized.

(9) There is no limitation for a material of the base body 3, provided that the material has tolerance to the solution. For example, the material of the base body 3 may be selected from a group consisting of: various kinds of plastics such as polyimide sheet, polyethylene terephthalate and so on; various kinds of metals such as copper, nickel, silver, gold, tungsten, molybdenum, platinum, palladium, iron, iron alloy and so on; various kinds of organic layered sheets, in other words, various kinds of layered sheets such as paper epoxy, glass epoxy, grass polyester and so on; various kinds of glass; ceramics; and so on.

(10) In the embodiment, a purpose of using the organic film 6 is not to insulate between the ferrite films 7 nor between the ferrite film 7 and an external member. As for a material of the organic film 6, a material having any specific electrical resistance may be used. For example, the organic film 6 may be made of resin selected from a group consisting of phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, polyimide, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, ABS resin, acrylic resin, polyamide, nylon, polyacetal, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, polymer liquid crystal, polyamide-imide and one of these resin including metal powder. The organic film 6 may be made of resin which includes magnetic powder. For example, a material of the magnetic powder may be selected from a group consisting of ferrite, Fe. FeCo alloy, FeSi alloy, Fe system alloy such as FeSiAl, Ni system alloy such as NiFe alloy and so on. Furthermore, the organic film 6 may be a high dielectric constant material made of resin which includes carbon or metal powder.

(11) In the embodiment, there is no limitation to a film formation method of the organic film 6. For example, the organic film 6 may be formed by applying a resin which has moderate fluidity by an applying apparatus such as a spin coater, or the organic film 6 may be formed by a film formation apparatus such as sputtering and so on.

(12) In the embodiment, the ferrite film(s) 7 is formed through the ferrite plating method. A film formation apparatus, for example as shown in FIG. 2, may be used for forming a ferrite plate. The illustrated film formation apparatus is an apparatus for forming a ferrite film on the base body 3 and comprises a reaction solution nozzle 1, an oxidizing solution nozzle 2 and a turn table 4. The turn table 4 is a table turnable around its axis. The base body 3 moves in response to the turning of the turn table 4. The reaction solution nozzle 1 is configured to supply a reaction solution for the turn table 4, wherein the reaction solution contains at least ferrous ions/Fe.sup.2+ ions). The reaction solution nozzle 1 is fixed above the turn table 4. The oxidizing solution nozzle 2 is configured to supply an oxidizing solution for the turn table 4, wherein the oxidizing solution contains at least an oxidizing agent. The oxidizing solution nozzle 2 is fixed above the turn table 4. In the illustrated film formation apparatus, the reaction solution nozzle 1 is positioned above one of half regions of the turn table 4 stopped, while the oxidizing solution nozzle 2 is positioned above the other half region of the turn table 4 stopped. When the turn table 4 is turned with the reaction solution and the oxidizing solution respectively supplied from the reaction solution nozzle 1 and the oxidizing solution nozzle 2, the reaction solution and the oxidizing solution are alternately supplied for the base body 3, and excess reaction solution and oxidizing solution are removed by centrifugal force. As a result, the ferrite film based on the ferrite plating method is formed on the base body 3. Compositions of the ferrite films 7 may be different from each other.

(13) In the embodiment, it is not the ferrite film 7 which is formed directly on the base body 3. However, for example, a magnetic film provided body 10a may comprise a magnetic film 5a formed by forming the ferrite film 7 directly on the base body 3, as shown in FIG. 3. In this case, the base body 3 may be made of an organic material. Similarly to the organic film 6, the organic material in this case is preferred to have a ratio t/E of 0.025 m/GPa or more. In this manner, the adhesive strength between the base body 3 made of the organic material and the organic film 7 directly formed thereon can be 0.1 kN/m or more. Furthermore, it is preferable to maintain a ratio of t/E of the organic material of the base body 3 to be 1000 /GPa or less.

(14) For a property examination of the magnetic film provided body, various magnetic film provided bodies were formed, as listed in the following table. In the table, each of concrete examples 15 is a magnetic film provided body which satisfies a condition according to the present embodiment, while each of comparative examples 15 is a magnetic film provided body which does not satisfy the condition according to the present embodiment.

(15) TABLE-US-00001 TABLE 1 Concrete Concrete Concrete Concrete Concrete Compar- Compar- Compar- Compar- Example Example Example Example Example ative Ex- ative Ex- ative Ex- ative Ex- 1 2 3 4 5 ample 1 ample 2 ample-3 ample 4 Material Fer- 2 Fer- 1 and Thick- rite rite ness (m) of 6th Layer Material Poly- 1 Poly- 0.1 and Thick- imide imide ness (m) B A of 5th Layer Material Fer- 2 Fer- 1 Fer- 0.5 and Thick- rite rite rite ness (m) of 4th Layer Material Poly- 1 Poly- 0.1 Poly- 20 Fer- 3 Fer- 3 and Thick- imide imide imide rite rite ness (m) B A B of 3rd Layer Material Fer- 2 Fer- 1 Fer- 0.5 Poly- 6 Epoxy + 20 Fer- 25 Fer- 18 and Thick- rite rite rite imide Fe rite rite ness (m) A of 2nd Layer Material Poly- 1 Poly- 0.1 Poly- 20 Fer- 3 Fer- 3 Poly- 2 Fer- 5 Poly- 0.05 Fer- 6 and Thick- imide imide imide rite rite imide rite imide rite ness (m) B A B A A of 1st Layer Material Glass 1000 Glass 1000 Glass 1000 Poly- 25 Poly- 25 Glass 1000 Glass 1000 Glass 1000 Poly- 25 and Thick- imide imide imide ness (m) of Base Body Total 6 3 1 6 6 25 5 18 6 Thickness (m) of the Ferrite Film Position between between between between between between between between between of the PET PET PET PET PET 1st Base Base Base Existence and and and and and layer Body Body Body of Ex- Double- Double- Double- Double- Double- and and and and foliation sided sided sided sided sided 2nd 1st 1st 1st tape tape tape tape tape layer layer layer layer Adhesive >2.0 >2.0 >2.0 >2.0 >2.0 0.05 Exfoli- 0.09 1 Strength ation between Occurs the Layers before (kN/m) the Test Young's 3 4 3 4 4 4 4 Modulus E GPa) of the Organic Film Film 1 0.1 20 6 20 2 4 Thickness t(m)of the Or- ganic Film t/E 0.33 0.025 6.67 1.5 5 0.5 0.01 (m/GPa) Occur- No Ex- No Ex- Exfoliation rence of foliation foliation Occurs the Ex- foliation after Bending Test (100,000 times)

(16) Hereinafter, a supplemental explanation will be made about a size and a fabrication condition of each of the examples listed in the table.

(17) A size of the base body 3 made of the glass substrate is 50 mm50 mm1 mm. A size of the base body 3 made of the polyimide sheet is 50 mm50 mm25 mm. The former corresponds to the concrete example 13 and the comparative example 13. The latter corresponds to the concrete example 4 and and the comparative example 4.

(18) In the above-mentioned examples of the organic films 6, Polyimide A is a polyimide film which has relatively high Young's modulus (Young's modulus of 4 GPa), and Polyimide B is a polyimide film which has relatively low Young's modulus (Young's modulus of 3 GPa). An explanation will be made for a forming method of the polyimide film with taking an example where the polyimide film is formed on a glass substrate. First, a dilute agent was added into and mixed with polyamic acid of a precursor of polyimide. Secondly, the aforementioned mixture was applied on a surface of the glass substrate by a spin coater. An application thickness was adjusted by viscosity of a solution, the number of revolutions of the spin coater, and so on. After that, the glass substrate applied with the solution was heated at 90 C. for 5 minutes, followed by heated at 320 C. for 60 minutes. Thus, the polyimide film was formed on the glass substrate. By adjusting the formation conditions, the organic films 6 can be obtained wherein the organic films 6 is made of the polyimide A of high Young's modulus (4 GPa) or the polyimide B of low Young's modulus (4 GPa).

(19) The organic film 6 of the concrete example 5 is a mixture of epoxy resin and Fe. As for the organic film 6. Fe particle was mixed into pre-polymer of epoxy resin, wherein Fe particle has an average particle diameter of 3 m and the Fe content was 45 vol %, and thereafter a curing agent was mixed. Next, the mixture was applied so that an average thickness is 2 m. Furthermore, the applied film was maintained at 100 C. for 6 hours and cured. A specific resistance of the mixture of epoxy resin and Fe formed in the above-described manner was 100 cm.

(20) The ferrite film 7 was formed as follows. As a pre-treatment, a turn table 4 was turned after the base body 3 was disposed on the turn table 4, while deoxidized ion-exchange water was provided on the base body 3 under a heat treatment up to 90 C. Next, nitrogen gas was introduced into the film formation apparatus so that deoxide atmosphere was prepared in the apparatus. Then, the step of supplying the reaction solution for the base body 3 from the reaction solution nozzle 1 and the step of supplying the oxidizing solution for the base body 3 from the oxidizing solution nozzle 2 were carried out while the turn table 4 was turned. In other words, the step of supplying the reaction solution and the step of supplying the oxidizing solution were carried out alternately and repeatedly. Here, flow rate upon the supply of each of the reaction solution and the oxidizing solution was set to 40 ml/min. The reaction solution was prepared by dissolving FeCl.sub.2-4H.sub.2O, NiCl.sub.2-6H.sub.2O and ZnCl.sub.2 into deoxidized ion-exchange water. The oxidizing solution was prepared by dissolving NaNO.sub.2 and CH.sub.3COONH.sub.4 into deoxidized ion-exchange water. The reaction solution and the oxidizing solution may be formed with reference to, for example, U.S. 2009-0047507A1, U.S. 2007-0231614A1, or other materials. Here, the explanation was made with taking an example where the ferrite film 7 was formed on the base body 3. Similar method was carried out for a case where the ferrite film 7 was formed on the organic film 6.

(21) Chemical composition of each ferrite film of the concrete example 15 and the comparative example 14 as listed on the table was examined by an inductively coupled plasma spectroscopy (ICPS) method. As a result, each of the ferrite films has an average composition of Ni.sub.0.2Zn.sub.0.3Fe.sub.2.5O.sub.4. A scanning electron microscope (SEM) was used for a configuration analysis such as measurement of film thickness.

(22) An examination of the adhesive strengths was carried out in conformance with JIS C5016 (test methods for flexible printed wiring boards). Peel strength was taken as the adhesive strength. In detail, as shown in FIG. 4, the obtained magnetic film provided body 10 was fixed on a stage 20 with a double-sided tape 22. A PET film 24 was stuck to the top layer of the ferrite film 7 by a double sided tape 22. In this state, the PET film was peeled off in the 90 direction. By recording a position of exfoliation occurred between the layers and the scale on a force gages at that time, the value of the scale was taken as the adhesive strength.

(23) An examination of the flexibility was carried out in conformance with JIS C5016 (a test method for flexible printed wiring boards). In detail, as shown in FIG. 5, the obtained magnetic film provided body 10 was bent, where the bending radius R was 3 mm. End portions of the magnetic film provided body 10 was fixed to a mount plate 30 and a vibration plate 32, respectively. In this state, a bending test was carried out for the vibration plate 32 which was subjected to the reciprocating motion for a hundred-thousand times, where each stroke is 30 mm and each reciprocate cycle is twice per second. After the bending test of the reciprocating motion for 100 thousand times, a visual examination was carried out to check the occurrence of the exfoliation between any layers. When there was no exfoliation as a result of the examination, flexibility was judged to be fine. The bending test was carried out only for the magnetic film provided body of which the base body is polyimide, as the glass substrate cannot be bent. The results of the examinations are also listed on the aforementioned tables.

(24) It is obvious from the tables that for the magnetic film provided bodies of the concrete examples 15, each adhesive strength between the organic film 6 and the ferrite film 7 is 0.1 kN/m or more because each organic film 6 has a thickness of 0.1 m to 20 m, both inclusive; each ferrite film(s) 7 has a thickness of 20 m or less; and a ratio t/E is of 0.025 m/GPa or more, where t indicates the thickness of the organic film, and E indicates Young's modulus of the organic film. Accordingly, no exfoliation occurs in the magnetic film provided body 10.

(25) On the other hand, for the magnetic film provided bodies of comparative examples 13, each adhesive strength in the magnetic film provided bodies are 0.1 kN/m or less because the condition such as thickness of the organic films, Young's modulus and thickness of the ferrite are not satisfied. This results in occurrence of the exfoliation between any layers of the magnetic film provided body 10. In the comparative example 4, exfoliation occurred after the 100 thousand times of the bending test. This is caused by the single layered ferrite film 7 formed on the base body 3 made of the organic material.

INDUSTRIAL APPLICABILITY

(26) A ferrite provided body according to the present invention can be used in an inductance element, an impedance element, a magnetic head, a microwave element, a magnetostriction element and a high-frequency magnetic device such as an electromagnetic interference suppressor. Especially, it is suitable in the case where the magnetic film including the ferrite film is required to be relatively thick. The electromagnetic interference suppressor is for suppressing electromagnetic problems caused by interferences of undesired electromagnetic waves in a high frequency region.