Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/33—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B13/00—Burglar, theft or intruder alarms
  • G08B13/22—Electrical actuation
  • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
  • G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0206—Manufacturing of magnetic cores by mechanical means
  • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
  • H01F41/041—Printed circuit coils
  • H01F41/046—Printed circuit coils structurally combined with ferromagnetic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type 
  • H01F17/04—Fixed inductances of the signal type  with magnetic core

Definitions

• the invention relates to an inductive component with at least one winding and a soft magnetic core made of a ferromagnetic material.
• the invention relates to inductive components with a soft magnetic core consisting of a powder composite material.
• pressed powder composites made of iron powder are known.
• the permeability range from approx. 10 to 300 can be covered well with these magnetic cores.
• the saturation inductances that can be achieved with these magnetic cores are around 1.6 Tesla.
• the application frequencies are typically below 50 kHz due to the comparatively low specific resistance and the size of the iron particles.
• Pressed powder composites made of soft magnetic crystalline iron-aluminum-silicon alloys are also known. With these, application frequencies up to over 100 kHz can be achieved due to the comparatively higher specific resistance.
• Both the injection molding process and the casting process with casting resins have the disadvantage that only packing densities in the powder composite materials of approximately a maximum of 55% by volume are achieved in relation to the processed alloy powders. This limits the total permeability of the inductive component that can be achieved. Furthermore, the achievable saturation induction of the powder composite is limited. Limiting the overall permeability and the saturation induction in turn limits the component properties, in particular in the case of storage chokes. Furthermore, the large internal shear of these powder composite materials causes an additional increase in the magnetic reversal losses due to stray field losses, which is also disadvantageous.
• the object of the present invention is therefore to achieve an increase in the packing density within the powder composite material. Associated with this is the task of increasing the effective permeabilities and the achievable saturation to achieve induction induction as well as the reduction of magnetic reversal losses in the resulting inductive components.
• Component with at least one winding and a soft magnetic core made of a ferromagnetic powder composite material, which consists of a ferromagnetic alloy powder made of an amorphous or nanocrystalline alloy and a ferromagnetic dielectric powder and a thermoplastic or thermosetting polymer.
• dielectric ferromagnetic powders as an admixture, the remaining “spaces” between the individual alloy particles can be “filled”, since such powders can be produced in much finer grains.
• inorganic powders for example ferrite powders
• ferrite powders are used as ferromagnetic dielectric powders.
• the ferrite powders are typically made from sintered ferrite parts by grinding in suitable mills. posed. Mn-Zn ferrites in particular (e.g. ferrite N 27) have proven to be particularly suitable due to their high saturation induction.
• surface-insulated metallic powders are used. Ferromagnetic carbonyl metal powders in particular have proven to be extremely suitable. The use of carbonyl iron powder, carbonyl nickel powder or carbonyl cobalt powder and mixtures of these carbonyl powders are conceivable.
• the carbonyl iron powders are high-purity iron powders which are produced using the "carbonyl process". Iron powders and carbon monoxide are produced under high pressure and at high temperatures from iron pentacarbonyl. The iron carbonyl thus produced is then separated from impurities by vacuum distillation and then specifically decomposes carbon monoxide and iron into its starting substances.
• the grain size can be set within certain limits by the targeted setting of the thermodynamic decomposition parameters.
• the resulting high-purity fine-grained iron powder naturally has a very low electrical resistance which is customary for metals, which is undesirable when the iron powder is used according to the invention.
• the powder is then surface-insulated, for example surface-phosphated.
• Both the ferrite powders and the surface-insulated metal powders are based on the commonality, unproblematic be able to be produced in powder particle sizes that are smaller than 10 ⁇ m. Particularly good results are achieved with dielectric ferromagnetic powders, the powder particles of which are smaller than 5 ⁇ m.
• the powders used according to the present invention are accordingly dielectric, which means here that they have no appreciable electrical volume or surface conductivity. This avoids the creation of additional eddy current paths from the outset.
• the powders used preferably have a density which corresponds approximately to the density of the amorphous or nanocrystalline alloys used. This avoids the occurrence of separation effects when mixing the powders with the alloy powders. However, it is also possible to use powders which have a very different density compared to the alloy powders used. Then, however, special care must be taken when compacting the mixture.
• Nanocrystalline alloys are preferably used for the alloy powders, as are described in detail, for example, in EP 0 271 657 A2 or in EP 0 455 113 A2. Such alloys are typically produced in the form of thin alloy strips, which are initially amorphous, using the melt spin technology described there, and are then subjected to a heat treatment in order to achieve the nanocrystalline structure. However, amorphous cobalt-based alloys can also be used.
• the alloys are ground to alloy powders with an average particle size ⁇ 2mm. Thicknesses from 0.01 to 0.04 mm and dimensions in the other two dimensions from 0.04 to 1.0 mm are optimal.
• the alloy particles are surface-oxidized for electrical insulation of the alloy particles from one another. On the one hand, this can be achieved by oxidizing the ground alloy particles in an oxygen-containing atmosphere. However, the surface oxidation can also be produced by oxidation of the alloy strip before grinding to an alloy powder.
• the alloy particles can be coated with a plastic, for example a silane or metal alkyl compound, the coating being carried out at temperatures between 80 ° C. and 200 ° C. for a period of 0.1 to 3 hours becomes. This procedure "burns" the coating into the alloy particles.
• a plastic for example a silane or metal alkyl compound
• the alloy powder prepared in this way is then mixed in a first embodiment of the present invention with the dielectric ferromagnetic powder in the desired ratio and then mixed in a heatable paddle mixer with an injection molding polymer as a binder.
• Polyamide 11 eg Rilsan
• the recipe can be added by other additives such as. B. flow improvers or antioxidants can be varied within the framework recommended by the manufacturer of the respective product.
• the material is melted, homogenized and then granulated with cooling.
• the mass prepared in this way can then be processed on the customary injection molding machines designed for processing masses filled with metal particles.
• the spray parameters are set depending on the type of machine used and the molding to be manufactured.
• the mixture is made of alloy powder and dielectric ferromagnetic powder cast with a resin.
• a polyamide or polyacrylate is particularly suitable.
• Powder and the cast resin formulation to form a cast resin powder formulation; c) filling the cast resin powder formulation into the mold; and d) curing the cast resin powder formulation.
• the alloy particles are not exposed to any mechanical stress during the manufacturing process. Furthermore, in particular when using a mold equipped with prefabricated windings, the insulation layer applied to the winding wires is not damaged, since by filling the casting resin formulation or casting resin powder formulation with the lowest possible viscosity into the mold due to the gentle introduction of the formulations, these applied insulation layers are not damaged , Cast resin formulations with viscosities of a few millipascal seconds are particularly preferred.
• Polymer building blocks which are mixed with a polymerization initiator are typically used as cast resin formulations.
• methacrylic acid methyl esters come into consideration as polymer building blocks.
• other polymer building blocks are also conceivable, for example lactams.
• the methacrylic acid methyl esters are then polymerized to polyacrylic during curing.
• the lactams are polymerized to polyamides via a polyaddition reaction.
• Possible polymerization initiators are dibenzoyl peroxide or, for example, 2,2 ⁇ - azo-isobutyric acid dinitryl.
• polymerization processes of the known casting resins are also possible, for example polymerizations which are triggered by light or UV radiation, that is to say largely without polymerization initiators.
• the mixtures of the ferromagnetic alloy powder and the dielectric powder are aligned during and / or after the mold has been filled with the powder mixture by applying a magnetic field.
• a magnetic field This can be done in particular when using molds which are already equipped with a winding by passing a current through the winding and the associated magnetic field.
• This application of magnetic fields which expediently have field strengths of more than 10 A / cm, aligns both the ferromagnetic alloy articles and the ferromagnetic dielectric powder particles.
• the losses can be greatly reduced and the permeability of the soft magnetic core and thus the inductance of the inductive component can be increased.
• a cast resin powder formulation is used, to achieve higher permeabilities of the soft magnetic core, it is advantageous to generate a magnetic field with the coil lying in the mold as soon as the cast resin powder formulation is filled, which leads to an orientation of the alloy particles and the dielectric powder particles in the direction of the magnetic flux causes.
• the mold After the mold is completely filled, it is first set to vibrate, which in turn can be done, for example, by the compressed air vibrator mentioned above and then the magnetizing current is switched off. After the casting resin formulation has finally hardened, the resulting inductive component is then removed from the mold.
• the figure shows an inductive component according to the present invention in cross section.
• the figure shows an inductive component 10.
• the inductive component 10 consists of a soft magnetic core 11 and a winding 12, which consists of relatively thick copper wire with few turns.
• the figure shows the component 10 during manufacture.
• the component 10 is introduced into a mold 1, which here consists of aluminum.
• the winding 12 is a layer winding bobbin, at the winding ends of which are connected with pins 13.
• the pins 13 protrude from the soft magnetic core 11 and are used for connection to a base plate, for example a printed circuit board.
• Form 1 shown also serves as housing 14.
• Starting material for the powder composite material is an initially amorphous alloy of the composition F ⁇ 73, 5 u l Nl:> 3 s IL5, 5 B 7 'which has been using the technology Rascherstarrungs- in the form of thin metal strips prepared. It is once again expressly noted that these production processes are explained in detail, for example, in EP 0 241 657 A2.
• alloy strips are then subjected to a heat treatment under hydrogen or in a vacuum at a temperature of approximately 560 ° C. in order to set a nanocrystalline structure.
• a heat treatment under hydrogen or in a vacuum at a temperature of approximately 560 ° C. in order to set a nanocrystalline structure.
• the alloy strips were crushed to the desired final fineness using a mill.
• the resulting alloy particle sizes typical for these processes were approximately between 0.01 and 0.04 mm in thickness and between 0.04 and 1.0 mm in dimension in the other two dimensions.
• the alloy particles thus produced which are also called flakes, have now been provided with a surface coating in order to improve their dynamic magnetic properties.
• a targeted surface oxidation of the alloy particles is first carried out by a heat treatment in the
• a HQi-quality carbonyl iron powder was then provided by BASF.
• the carbonyl iron powder had a grain size of less than 5 ⁇ m.
• the surface oxidized alloy powder and carbonyl iron powder were then mixed together in a weight ratio of approximately 7: 3, i.e. about 7 kg of alloy powder was blended with about 3 kg of carbonyl iron powder.
• the two powders were homogenized in a suitable mixer and then filled into the desired shape.
• Form 1 which was made of aluminum, had a suitable separating coating on its inner wall, so that it was not possible for the inductive component 10 to be demolded more difficultly.
• An electrical current was then passed through the winding 12, so that the ferromagnetic alloy particles and the ferromagnetic dielectric powder particles were aligned with their “long axes” parallel to the resulting magnetic field, which was approximately 12 A / cm.
• a cast resin formulation was then poured into the filled mold.
• the cast resin formulation used consisted of a thermoplastic methacrylate formulation with a silane coupling agent.
• This thermoplastic methacrylate formulation had the following composition: 100 g methyl methacrylate 2 g methacryl trimethoxysilane 6 g dibenzoyl peroxide and 4.5 g N, N-dimethyl-p-toluidine
• the chemical components were dissolved one after the other in methacrylic ether.
• the finished mixture was water-clear and was poured into Form 1.
• the cast resin formulation cured at room temperature in about 60 minutes. Then it was post-cured at about 150 ° C for another hour.
• a magnetic core was achieved with a packing density of ferromagnetic material in the range of approximately 65 vol%.

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• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Soft Magnetic Materials (AREA)

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• 2001
  • 2001-06-08 DE DE10128004A patent/DE10128004A1/de not_active Withdrawn
• 2002
  • 2002-04-26 JP JP2003504422A patent/JP2004529508A/ja active Pending
  • 2002-04-26 US US10/476,901 patent/US7532099B2/en not_active Expired - Fee Related
  • 2002-04-26 WO PCT/EP2002/004644 patent/WO2002101763A1/de active Application Filing
  • 2002-04-26 EP EP02742919A patent/EP1393330A1/de not_active Withdrawn

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