Magnetic polymer composition for electronic products

 

(57) Abstract:

The invention relates to electrical engineering, in particular to magnetic polymer compositions intended for use in high frequency and microwave radio devices. The material is a thermoplastic polymer matrix containing uniformly distributed magnetically ordered single-domain particles of nanometric size from 1 to 30 nm with a concentration of up to 50 wt.%, chemically bonded with the matrix material. Particles are formed in a matrix in the process of obtaining material in thermal decomposition of metal-containing compounds. Magnetic properties of the material can be controlled by choice of the matrix, particle composition, and technological modes of production of the material. Products material can be manufactured using plastics technology. The technical result of the invention is to simplify the technology of magnetic material and providing a low loss switching of magnetization in the material in the field of high and ultrahigh frequencies. 3 C.p. f-crystals.

The invention relates to compositions and may be used as the magnetic components in the radio I currently widely used in radio engineering [1-3]. They are used as cores in transformers, inductors, such high frequency devices, such as resonators, phasers, valves, circulators, antennas. Ferrites are made in ceramic technology from the oxides of the respective metals by thermal decomposition of metal salts and method of joint precipitation of hydroxides or carbonate salts of metals [2, 3]. All of these methods are quite complex multistage processes, including operations such as obtaining powders by grinding, calcining, roasting and sintering at high temperatures (up to 1300 C), pressing under high pressure. The presence of difficult-to-control physico-chemical processes at different stages of the technological process, as well as the difficulty of ensuring tight control of process parameters do not allow for sustainable reproducibility of properties of ferrites and products from them. In particular, an important parameter of the ferrite obtained by ceramic technology is the grain size, which determines such characteristics as speed and magnetic susceptibility. However, this option may change in the process termoobrabotka has an activity of oxide, heavily dependent on the method and temperature conditions of its production, as well as the degree of grinding of oxide and the presence of impurities. It should be noted the fragility of ferrites and arise from the difficulty in handling and application. In addition, the ferrite is difficult to obtain products of complex shapes, products with tight tolerances on dimensions, thin films, and it is difficult to cause the ferrite coating on the surface of a complex configuration. Thin ferrite film (thickness of 10 to several hundred microns) is obtained by rolling a mixture of ferrite powder and various plasticizers with subsequent sintering at high temperatures [7], which hampers their use in a single technological process with semiconductor elements. There are methods of deposition of ferrite films as high-frequency sputtering ferrite targets in vacuum [8], pulsed laser evaporation [9], chemical vapor deposition [10]. However, obtained in this way film does not have a high quality and used equipment is expensive. In addition, these methods are unsuitable for film deposition on large surfaces.

Closest to the proposed invention is Aut a composition, consisting of a magnetic powder and a polymer binder. As the magnetic powder used ferromagnetic alloys of alsever, permalloy, and carbonyl iron. It should be noted the necessity of preliminary manufacturing powder or alloy powder carbonyl iron. As polymer binders are used bakelite, polystyrene, liquid glass, stekloemali. Thus, the ferrites is a mechanical mixture of magnetic powder and a polymer. Such materials are characterized by high stability of the magnetic properties. In addition, the use of ferrites allows to obtain products higher than in ceramic technology, accuracy classes, because it uses the same technology as in the manufacture of plastics. The disadvantages of ferrites should include the difficulty of adjusting the grain size of the magnetic powder, particularly of harvest less than 1 μm, which is important for producing high-frequency materials, as well as some complicated process, requiring pre-fabrication of the magnetic powder.

The present invention can simplify the manufacturing technology of mechanically durable vyskytla complex shape and magnetic layers on surfaces of complex shape, and regulation of the magnetic properties of the material within wide limits.

This task is solved in that as the material is a composition containing uniformly distributed in the polymer matrix of magnetically ordered single-domain particles of nanometric size (nanoparticles) formed in the matrix during the manufacturing process of the material and having a chemical bond with the matrix material.

The polymer matrix has a crystalline and an amorphous portion and a crystalline portion is from 60 to 80% of the volume of the matrix. The nanoparticles are formed in the cavities located in the amorphous part. As the polymer matrix are polymers, razmyagchayuschiesya when heated and hardens when cooled, such as polyethylene, polypropylene, polycarbonate, polystyrene, polyethylene, polyamide, nylon, nitrile, sulfochlorinated polyethylene.

Magnetic nanoparticles may have a size of from 1 nm to 30 nm and consist of 3d transition metals Fe, Co, Ni, Mn, CR, and rare earth metals (subgroup lanthanum), their oxides, or a combination of these metals or oxides, and carbon, nitrogen, silicon, germanium, and boron. Concentration of the nanoparticles in the matrix can be up to 50 wt.%. Material neocatechumenal condition.

The material is produced by a method of high thermal decomposition of compounds containing metal. For this purpose in the appropriate polymer melt is introduced containing the metal compound, combination of compounds or their solutions, which result in exposure to high temperatures decompose with the release of metal or metal oxide and the subsequent formation of particles of nanometric size in the cavities of the amorphous part of the polymer during cooling of the polymer mass.

Formed in the polymer particles are associated chemically with the matrix material. The metal particles are in the composition of the surface layer of a carbide of the metal. The resulting nanoparticles can contain one metal, several metals, carbon, silicon, germanium, boron, oxygen. As containing the metal of the substances used in the method of thermal decomposition, are used CARBONYLS, acetate, formate, ORGANOMETALLIC compounds of the form RnMM'Xm(where R is an organic radical, M is Fe, Co, MP, SG; M’ is a rare earth metal, C, Xm- volatile organic radical).

Magnetic properties of the material can be controlled by selection of the modes of its receipt (the temperature is x parameters can change the size of the particles, their anisotropy, the magnetic state of the system of particles (superparamagnetism or blocked state), magnetic susceptibility, magnetization and other magnetic parameters. Because of the small particle size (30 nm) possible rapid change of the magnetization in an external field due to the rotation vector of the magnetic moment of a single particle. This provides a low loss switching of magnetization in the material in the field of high and ultrahigh frequencies. It should be noted that such a small grain size cannot be obtained in any ferrites produced by ceramic technology, nor in magnetic dielectrics, where the grinding below a certain particle size are observed processes of agglomeration. Good dielectric properties of polymers and the absence of electrical contact between the nanoparticles provides a low dielectric loss and high voltage dielectric breakdown of the material.

The resulting process described above thermal decomposition of metal-containing compounds in the melt polymer material is a powder, from which you can obtain products of the desired configuration, using the technology of production plastmasine lower temperatures (several hundred degrees Celsius), than the temperature used in ceramic technology for ferrites. For the manufacture of magnetic films of polymeric material of a specified thickness can be used, for example, calendering method, representing a multi-step rolling material.

The following example illustrates but does not limit the essence of the invention.

Sample containing 45 wt.% Fe in the polyamide matrix was obtained by thermal decomposition of PENTACARBONYL iron Fe(CO)5in the melt of the polyamide at a temperature of 320 C in the following reactions

Fe(CO)5=Fe+CO.

X-ray small-angle scattering, transmission electron microscopy and mössbauer studies have shown the presence in the sample to a particle size of 5 nm, which consists of 90% of iron, and containing the oxide and iron carbide. For carrying out magnetic measurements by pressing under a pressure of 100 atmospheres at a temperature of 150 were obtained With a plate thickness of 5 mm and a diameter of 30 mm, and the ring height of 5 mm, an outer diameter of 20 mm and an inner diameter of 10 mm magnetization Measurements showed that at room temperature the sample is superparamagnetic particles in the state with much of the curve and the dependence of the magnetization on the field was not observed. The initial relative magnetic permeability of the sample, measured at a frequency of 100 Hz in a field amplitude of 1 e, $ 3. Elastic relative magnetic permeability (real component of the complex relative magnetic permeability), defined on the annular core at a frequency of 100 MHz was 17 when the total loss tangent in the sample of 0.05. These options allow you to use this material as the magnetic components in the radio devices in the field of high frequencies.

Sources of information

1. Rabkin L. I. high-Frequency ferromagnetic. Moscow, 1960, 528 S.

2. Mishin, D. D. Magnetic materials. M: The High. HQ., 1991, 384 S.

3. Transfiguration A. A., Richard E., Magnetic materials and elements. M: The High. HQ., 1986, 352 S.

4. U.S. patent No. 4247500, January 27, 1981

5. U.S. patent No. 4719027, January 12, 1988

6. U.S. patent No. 5120366, June 9, 1992

7. U.S. patent No. 5772820, June 30, 1998

8. U.S. patent No. 5460704, October 24, 1995

9. U.S. patent No. 5320881, July 14, 1994

10. U.S. patent No. 6030454, February 29, 2000

1. Magnetic polymer composition for electronic products, characterized in that it contains uniformly distributed in the polymer will matricul communication with the matrix material and formed in the matrix during the manufacturing process of the magnetic composition by high-speed thermal decomposition in the melt polymer matrix compounds, containing the metal in the form of solutions.

2. The composition according to p. 1, wherein the magnetic nanoparticles comprise transition metals: Fe, Co, Ni, Mn, CR, and rare earth metals of subgroups of lanthanum, oxides, or combinations of these metals or oxides, and carbon, nitrogen, silicon, germanium and boron.

3. The composition according to p. 1, characterized in that the polymer matrix are polymers, razmyagchayuschiesya when heated and hardens when cooled, such as polyethylene, polypropylene, polycarbonate, polystyrene, polyethylene, polyamide, nylon, nitrile, sulfochlorinated polyethylene.

4. The composition according to p. 1, characterized in that its manufacturing method is used, high-speed thermal decomposition in the melt polymer compounds containing metal, such as CARBONYLS, acetate, formate metals, ORGANOMETALLIC compounds of the form RnMM'Xmwhere R is an organic radical, M is Fe, Co, MP, SG; M’ is a rare earth metal; C, Xm- volatile organic radical, solutions or combinations.

 

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