TWI523954B - A method for making electromagnetic wave shielding material - Google Patents

Description

Method for manufacturing electromagnetic wave shielding material

The invention relates to electromagnetic wave absorption technology, in particular to a method for manufacturing electromagnetic wave shielding material.

The waveforms and energy required by the system and the line can be called "signals". The signals that are not required by the system and the line are called "noise." When the noise energy is too large or the system function is damaged, it can be called interference. If the form of interference is electromagnetic energy or waveform, it is called electromagnetic interference (EMI), and the protection system or circuit to prevent EMI acts or devices is called electromagnetic shielding (EMS), when the system or line When there is no EMI problem through EMS protection, it can be called Electromagnetic Compatibility (EMC).

In recent years, with the rapid development of wireless communications, the regulatory standards of countries around the world have become increasingly strict. As modern electronic products become more powerful and faster, and electronic circuits are becoming more dense and complex, EMI and EMC issues have become major design challenges, such as Bluetooth, GPS, and RFID. Key technologies in class applications. At present, electromagnetic wave shielding materials mainly include metal plates, foamed metals, metal conductive coatings, metal amorphous materials, metal-filled composite materials and the like.

Sheet metal shielding materials are generally divided into two categories: 1. Good conductor type shielding materials, which are commonly used for electrostatic fields and shielding of high and low frequency electromagnetic fields, such as copper, aluminum, nickel, etc. due to their high electrical conductivity; Ferromagnetic shielding materials, which are commonly used for shielding of low frequency fields due to their high magnetic permeability, such as iron and niobium steel alloys, but have low electrical conductivity and are not suitable for shielding of high frequency electromagnetic fields.

The foamed metal is a porous material composed of a metal skeleton and a connected air, such as a foamed metal nickel, a foamed metal copper nickel, and a foamed metal aluminum. Foamed metal is used in the manufacture of precision instruments due to its light weight, high specific strength and good electromagnetic shielding performance. For the thermal structural member, the shielding mechanism is mainly the multiple reflection attenuation and absorption attenuation of the electromagnetic wave by the cavity. However, it has the following disadvantages: 1. Once the bulk density of the foamed metal exceeds a certain critical value, it has little effect on the electromagnetic shielding performance of the material; 2. The smaller the pore size of the foamed metal, the better the shielding performance, but To achieve a good pore size, the preparation of the material becomes more complicated; 3. The mechanical properties of the foamed metal are poor and cannot be used alone as a structural material.

The metal conductive coating is a material prepared by mixing and dispersing metal fine powder having good electrical conductivity. Commonly used metal conductive coatings are silver, nickel and copper. Silver coatings have good electrical conductivity but are expensive. Copper-based coatings have good electrical conductivity and moderate price, but their chemical properties are active and the surface is easily oxidized to make them poor in electrical conductivity. The nickel-based coating has better shielding effect in the frequency band, but the low frequency and high frequency band are poor. The research indicates the electromagnetic shielding performance of micron-nickel powder coatings doped with metal fibers. If a small amount of metal fibers are added to the micron nickel powder material, the shielding effectiveness of the material in the low frequency range (9 kHz to 500 MHz) is better.

Metal-filled composite materials, filled composite materials are generally composed of a polymer substrate and a conductive filler with excellent electrical conductivity and certain additives, and are processed by extrusion molding, injection molding or compression molding. The effect of the filled composite on the electromagnetic shielding mainly depends on the conductivity of the conductive filler and the degree of mutual overlap between the fillers. Commonly used conductive fillers are metal-based metal sheets, metal fibers or powders, metal-plated glass fibers, carbon fibers, carbon, and the like. After the metal-based conductive filler reaches a certain filling amount in the polymer, a conductive network of a certain structure can be formed to form an effective electromagnetic shielding.

The metal fiber has a larger aspect ratio and contact area than the metal powder, so in the case of the same filling amount, the metal fiber is more likely to form a conductive network, and the electrical conductivity is high, and the electromagnetic shielding effect is better. After the metal-based conductive filler reaches a certain filling amount in the polymer, a conductive network of a certain structure can be formed to achieve effective electromagnetic shielding. Due to the high filling amount of powder conductive filler, the mechanical properties of the plastic are degraded. Therefore, fibrous, spherical, mesh, dendritic or sheet-like fillers are generally used to manufacture conductive plastics, but the disadvantage is that the shielding effect is susceptible to mixing uniformity. Impact.

Amorphous alloys have made great progress in the application of magnetic devices such as transformers, switching power supplies, precision measuring instruments, and magnetic heads. Its shielding performance is superior to conventional materials because it utilizes the magnetic bypass principle to direct the electromagnetic energy generated by the field source so that it does not enter the protection zone. Amorphous alloy mask materials can be divided into amorphous structural shielding materials and amorphous screens according to their application forms. Cover paint. The alloys commonly used in amorphous structural materials are mainly iron-based, iron-nickel-based, cobalt-based, etc., due to the high initial permeability and low high-frequency loss, high strength and wear resistance of the cobalt-based materials. widely used. In addition, the addition of magnetic elements (such as iron cobalt nickel) can increase the product of the relative conductivity and magnetic permeability of the amorphous alloy, which is beneficial to absorb electromagnetic waves. Amorphous mask coatings mainly use thermal spraying technology to form a certain thickness of coating on the surface of plastic, steel plate, permalloy, etc., in order to achieve the purpose of electromagnetic shielding, and overcome the shortcomings of traditional ferromagnetic materials during processing and high cost. Therefore, the amorphous alloy has high strength, high hardness, good corrosion resistance, excellent soft magnetic properties and magnetic mask properties, but its disadvantage is that the conductivity is not good, and the electromagnetic shielding function is not as good as the absorbing effect.

In order to improve the electromagnetic shielding effect of the amorphous shielding material in different frequency regions, the present invention discloses a novel preparation method, which has the characteristics of amorphous, conductive and magnetic conductive, and can be used as a novel electromagnetic shielding material.

In view of the shortcomings of the conventional technology, the present invention provides a method for fabricating an electromagnetic wave shielding material by using a microwave rapid displacement reaction to prepare a quaternary alloy of copper, iron, aluminum and tantalum powder, the principle of which is mainly for the surface of the iron-aluminum-niobium alloy, the dissolved portion. The iron ion and the copper atom generate a displacement reaction, and a method for producing an electromagnetic wave shielding material having different iron/copper ratios can be obtained.

The invention provides a method for manufacturing an electromagnetic wave shielding material, which comprises the steps of: mixing a ternary alloy iron-aluminum lanthanum powder with a solvent to prepare an iron-aluminum lanthanum solution; adding an acid to the iron-aluminum lanthanum solution to generate a dissolution reaction to cause iron Ion release; adding a copper chloride powder to the iron-aluminum solution; adding an alkali solution to the iron-aluminum solution, causing a displacement reaction; and adding a decane coupling agent to the iron-aluminum solution; The iron-aluminum solution is placed in a microwave reactor for microwave reaction to accelerate the displacement reaction; the iron-aluminum solution is subjected to a displacement reaction to form a quaternary alloy copper, iron, aluminum and tantalum to form a quaternary alloy copper, iron, aluminum and lanthanum solution. The quaternary alloy copper iron aluminum crucible solution is subjected to solid-liquid separation and drying treatment to obtain a solid powder electromagnetic wave shielding material.

The invention provides a method for manufacturing an electromagnetic wave shielding material, which differs in the conventional technology in that the conventional method directly mixes different proportions or different kinds of solid powders, and the powder quality generated by the method and the added raw materials and stirring methods thereof There is a great relationship that makes the uniformity and quality of the powders of various ingredients difficult to control. In addition, the powders of various components prepared by the conventional method are susceptible to the uneven proportion, which affects the reproducibility of the electromagnetic shielding function. This hair An electromagnetic wave shielding material is produced by using a copper-iron reduction potential difference, first dissolving the surface of the original iron-aluminum-bismuth alloy substrate with an acid, so that some iron ions are eluted on the surface of the alloy, and then the dissolved iron ions are The copper atom undergoes a displacement reaction, and the reaction time is accelerated by a microwave reaction to reduce the operation cost. The copper element can be precipitated on the surface of the iron-aluminum crucible to form a copper-iron-aluminum tantalum powder, and a uniform quaternary alloy powder can be obtained, which can effectively solve the uneven powder composition. The problem. In the present invention, a decane coupling agent is further added during the reaction, and an anti-oxidation layer is formed on the surface of the copper-iron-aluminum cerium powder, which has better corrosion resistance. The quaternary alloy copper, iron, aluminum and tantalum powder produced by the invention has magnetic permeability characteristics, and can be used for absorbing applications in addition to electromagnetic shielding requirements.

The above summary, the following detailed description and the accompanying drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

S1~S7‧‧‧ Process steps

1 is a flow chart showing the steps of a method for fabricating an electromagnetic wave shielding material according to the present invention.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate other advantages and functions of the present invention from the disclosure herein.

A flow chart of a method for fabricating an electromagnetic wave shielding material according to the present invention is shown in FIG. 1. The manufacturing method comprises the following steps: (a) mixing a ternary alloy iron-aluminum lanthanum powder with a solvent to prepare an iron-aluminum lanthanum solution S1, wherein The ternary alloy iron-aluminum tantalum powder type may be in the form of flakes, irregulars or granules, and the particle size ranges from 1 to 100 micrometers. The solvent may be pure water, and the solid content ratio of the iron-aluminum lanthanum solution is 60 to 100%; (b) adding an acid to the iron-aluminum solution, causing a dissolution reaction to release iron ions from S2, the principle of which is to dissolve the iron-aluminum-lanthanum surface alloy component by an acid, further generating a dissolution reaction to release the iron ion The weight ratio of the acid to the iron-aluminum solution is 1:1 to 1:100. The acid to be added may be one or a mixture of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, and the concentration of the acid may be 10% to 90%; (c) adding copper chloride powder S3 to the iron-aluminum solution For performing a chemical reaction, the copper chloride powder may be one or a mixture of monovalent copper or divalent copper, and the weight ratio of the copper chloride powder to the iron-aluminum solution is 1:50 to 1: 100; (d) adding an alkali solution to the iron-aluminum solution, such that the iron-aluminum solution produces a displacement reaction S4, which is one or a mixture of ammonia water or sodium hydroxide, and the iron-aluminum solution The Ph value after the addition of the lye is in the range of 5 to 11; (e) adding the decane coupling agent S5 as the interface modifier, which may be 10% to 90% by mass. a decane coupling agent which uses vinyltriethoxysilane (VTEO) or 3-methacryloxy-propyl-trimethoxysilane (abbreviated as 3-methacryloxy-propyl-trimethoxysilane). MEMO) One or two of the compounds, the chemical formula of the decane coupling agent is:

Wherein R is CH ₃ , C ₂ H ₅ or (CH ₂ ) ₂ OCH ₃ , Y is an organofunctional group, and n is 0 or 3, and the Y functional group may be CH=CH ₂ (vinyl group), H ₂ N (amino group), CH ₂ =CHCH ₃ COO (methacryloxy group); (f) the iron-aluminum solution is placed in a microwave reactor for microwave reaction to accelerate the displacement reaction S6, the microwave reaction time can be For 1 to 60 minutes, the microwave power may be 50 to 300 W; (g) the iron-aluminum lanthanum solution is subjected to a displacement reaction to form a quaternary alloy copper-iron-aluminum lanthanum to form a quaternary alloy copper-iron-aluminum lanthanum solution, the quaternary alloy The copper-iron-aluminum lanthanum solution is subjected to centrifugal washing to separate the solid and liquid, and the separated quaternary alloy copper-iron-aluminum lanthanum solid powder is taken out, and the solid powder is dried to obtain a solid powder electromagnetic wave shielding material S7. The step of the centrifugal washing is performed by using a centrifuge, and the drying step is vacuum drying. The ratio of the mass percentage of the quaternary alloy copper, iron, aluminum and tantalum is: aluminum 5~7%, 矽5~7%, Iron 60~76%, copper 10~30%.

The invention provides a method for preparing an electromagnetic wave shielding material, which adopts a microwave reactor to perform a displacement reaction, in addition to greatly reducing the production time, by controlling the parameters of the microwave reactor and adjusting various parameters in the process, including adding different acids. Liquid, lye, pH adjustment, iron The ratio of aluminum strontium powder and copper chloride can control the different powder types, composition ratios and particle size of the output.

The invention provides a method for fabricating an electromagnetic wave shielding material. The preferred embodiment of the present invention has the following steps: firstly, 15 g of iron-aluminum tantalum powder is used, wherein the proportion of aluminum barium iron mass percentage is 7~9% of aluminum, 矽6~ 8%, iron 82~88%, dissolved in 50g concentrated hydrochloric acid pre-stirred treatment, slowly pour copper chloride into the above solution, add ammonia water to cause displacement reaction in the iron-aluminum solution and stir for 30~60 minutes, then add 10 A milliliter of 5% decane coupling agent solution was placed in a microwave reactor and the model was a Discover microwave reactor for microwave reaction treatment. The iron-aluminum solution before the reaction was a black aqueous solution. The solution was poured into a 100 mL round bottom flask, placed in a microwave reactor and connected to a condenser tube for microwave reaction. The microwave reaction conditions and parameters were as follows: the microwave wattage was fixed at 150 W, the reaction temperature was 75 ° C, the reaction time was 5 minutes, and air cooling (PowerMAX) was initiated. After the reaction is completed, the microwave reactor cools the reactants to 50 ° C by the air of the air pump to obtain a quaternary alloy copper iron aluminum crucible solution. The function of air cooling (PowerMAX) is to continuously cool the reaction vessel by means of a cooling gas and simultaneously perform microwave irradiation. Since the conventional microwave reactor automatically reduces or completely shuts down the microwave power when the temperature reaches the set temperature, the conventional thermochemical action will replace the microwave heating chemistry. However, if the air cooling (PowerMAX) function is used, the reaction is continuously performed. The introduction of high-pressure air to cool the reactants confirmed that the microwave heating chemistry was performed during the reaction.

In this embodiment, in order to verify the quality of the quaternary alloy copper, iron, aluminum and tantalum obtained by the microwave reaction, the present invention may further comprise the following steps: placing the quaternary alloy copper, iron, aluminum and lanthanum solution into the centrifuge cup, after passing through four The mixture was washed by centrifugation, and the solute was vacuum dried at 80 ° C for 5 hours to form a dry quaternary alloy copper iron aluminum crucible powder.

In summary, the present invention provides a method for fabricating an electromagnetic wave shielding material, which can easily produce a quaternary alloy copper, iron, aluminum, tantalum powder having better electromagnetic wave shielding performance than the conventional technology, and has the characteristics of rapid reaction and easy process. It is suitable for commercial 3C product shielding materials used in mass production and cost control.

The above-described embodiments are merely illustrative of the features and functions of the present invention, and are not intended to limit the scope of the technical scope of the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, this issue The scope of protection of the rights of Ming Dynasty shall be as listed in the scope of application for patents mentioned later.

S1~S7‧‧‧ Process steps

Claims (12)

A method for manufacturing an electromagnetic wave shielding material, comprising the steps of: mixing a ternary alloy iron-aluminum lanthanum powder with a solvent to prepare an iron-aluminum lanthanum solution; adding an acid to the iron-aluminum lanthanum solution to generate a dissolution reaction to release the iron ions; Adding a copper chloride powder to the iron-aluminum solution; adding an alkali solution to the iron-aluminum solution to cause a displacement reaction; adding a decane coupling agent to the iron-aluminum solution; The ruthenium solution is placed in a microwave reactor for microwave reaction to accelerate the displacement reaction; the iron-aluminum lanthanum solution is subjected to a displacement reaction to form a quaternary alloy copper-iron-aluminum lanthanum to form a quaternary alloy copper-iron-aluminum lanthanum solution, and the quaternary alloy is formed. The alloy copper, iron, aluminum and lanthanum solution is subjected to solid-liquid separation and drying treatment to obtain a solid powder electromagnetic wave shielding material; wherein the ratio of the mass percentage component of the quaternary alloy copper, iron, aluminum and tantalum is: aluminum 5~7%, 矽5~ 7%, iron 60~76%, copper 10~30%. The method for producing an electromagnetic wave shielding material according to claim 1, wherein the solvent is pure water. The method for producing an electromagnetic wave shielding material according to claim 1, wherein the iron-aluminum solution has a solid content ratio of 60 to 100%. The method for producing an electromagnetic wave shielding material according to claim 1 or 2, wherein the weight ratio of the acid to the iron-aluminum solution is 1:1 to 1:100. The method for producing an electromagnetic wave shielding material according to claim 1, wherein the acid is one or a mixture of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, and the concentration percentage of the acid is 10% to 90%. . The method for producing an electromagnetic wave shielding material according to claim 1, wherein the weight ratio of the copper chloride powder to the iron-aluminum solution is 1:50 to 1:100. The method for producing an electromagnetic wave shielding material according to claim 1, wherein the microwave reaction time is from 1 to 60 minutes. The method for fabricating an electromagnetic wave shielding material according to claim 1, wherein the microwave power is 50 to 300 W. A method for fabricating an electromagnetic wave shielding material according to claim 1, wherein the method The lye is one of or a mixture of ammonia water or sodium hydroxide. The method for fabricating an electromagnetic wave shielding material according to the first aspect of the invention, wherein the Ph-value of the iron-aluminum solution after adding the alkali solution is in the range of 5 to 11. The method for producing an electromagnetic wave shielding material according to claim 1, wherein the ratio of the decane coupling agent is 10% to 90% by mass. The method for producing an electromagnetic wave shielding material according to the first aspect of the invention, wherein the drying treatment is vacuum drying.