10 major application areas of silicon micropowder
Silica powder is a kind of inorganic non-metallic material with wide applications. Silica powder is a micron-level powder obtained by crushing and pulverizing high-purity quartz ore by physical or chemical methods. Its particle size is generally between 1-100 microns, and the commonly used particle size is about 5 microns. With the advancement of semiconductor manufacturing processes, silica powder below 1 micron has gradually been widely used.
Silica powder has a series of advantages such as excellent dielectric properties, low thermal expansion coefficient, high thermal conductivity, high chemical stability, high temperature resistance, and high hardness. It can be widely used in copper clad laminates, epoxy molding compounds, electrical insulation materials, and adhesives. In addition, it can also be used in coatings, rubber, plastics, cosmetics, and honeycomb ceramics.
1 Copper clad laminate
Adding silicon powder to copper clad laminate for electronic circuits can improve the linear expansion coefficient and thermal conductivity of printed circuit boards, thereby effectively improving the reliability and heat dissipation of electronic products.
2 Epoxy molding compound (EMC)
Filling silicon powder into epoxy molding compound for chip packaging can significantly improve the hardness of epoxy resin, increase thermal conductivity, reduce the exothermic peak temperature of epoxy resin curing reaction, reduce linear expansion coefficient and curing shrinkage, reduce internal stress, and improve the mechanical strength of epoxy molding compound, making it infinitely close to the linear expansion coefficient of the chip.
3 Electrical insulation materials
Silicon powder is used as epoxy resin insulation filler for electrical insulation products. It can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during the curing process, reduce internal stress, and improve the mechanical strength of the insulating material, thereby effectively improving and enhancing the mechanical and electrical properties of the insulating material.
4 Adhesives
Silicon powder, as an inorganic functional filling material, is filled in adhesive resin, which can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during curing, improve the mechanical strength of the adhesive, and improve the heat resistance, anti-permeability and heat dissipation performance, thereby improving the bonding and sealing effect.
5 Plastics
Silicon powder can be used in plastics in products such as polyvinyl chloride (PVC) flooring, polyethylene and polypropylene films, and electrical insulation materials.
6 Coatings
In the coatings industry, the particle size, whiteness, hardness, suspension, dispersibility, low oil absorption, high resistivity and other characteristics of silicon micropowder can improve the corrosion resistance, wear resistance, insulation and high temperature resistance of the coating. Silicon micropowder used in coatings has always played an important role in coating fillers due to its good stability.
Spherical silica powder has good fluidity and large specific surface area, which makes it suitable for cosmetics such as lipstick, powder, foundation cream, etc. In powder products such as powder, it can improve fluidity and storage stability, thereby playing a role in preventing caking; the smaller average particle size determines its good smoothness and fluidity; the larger specific surface area makes it have better adsorption, can absorb sweat, fragrance, nutrients, and make cosmetic formulas more economical; the spherical shape of the powder has good affinity and touch to the skin.
8 Honeycomb ceramics
Automobile exhaust filter DPF made of honeycomb ceramic carrier for automobile exhaust purification and cordierite material for diesel engine exhaust purification is made of alumina, silica powder and other materials through mixing, extrusion molding, drying, sintering and other processing.
9 Rubber
Silicon powder is a reinforcing material for rubber. It can enhance the comprehensive properties of rubber, such as strength, toughness, elongation, wear resistance, finish, anti-aging, heat resistance, anti-slip, tear resistance, acid and alkali resistance, etc. It is indispensable in the production process of rubber products.
10 Artificial quartz
Silicon powder is used as a filler in artificial quartz board, which can not only reduce the consumption of unsaturated resin, but also improve the wear resistance, acid and alkali resistance, mechanical strength and other properties of artificial quartz board. The filling ratio of silicon powder in artificial marble is generally about 30%.
Key raw material for solid electrolytes—Zirconia
ZrO2 is an oxide material with high temperature resistance, high hardness and good chemical stability. It has high melting point and boiling point, so it can maintain stable physical and chemical properties in high temperature environment. In addition, ZrO2 also has a low thermal expansion coefficient and good electrical insulation properties. This makes it one of the preferred raw materials for LLZO solid electrolyte.
High hardness: The hardness of ZrO2 is second only to diamond, and it has high wear resistance.
High melting point: The melting point of ZrO2 is very high (2715℃). The high melting point and chemical inertness make ZrO2 a good refractory material.
Excellent chemical stability: ZrO2 has good resistance to chemicals such as acids and alkalis and is not easily corroded.
Good thermal stability: ZrO2 can still maintain good mechanical properties and chemical stability at high temperatures.
Relatively large strength and toughness: ZrO2, as a ceramic material, has a large strength (up to 1500MPa). Although the toughness is far behind some metals, compared with other ceramic materials, zirconium oxide has a higher fracture toughness and can resist external impact and stress to a certain extent.
There are various preparation processes for ZrO2, including pyrolysis, sol-gel, vapor deposition, etc. Among them, pyrolysis is one of the most commonly used preparation methods. This method reacts zircon and other raw materials with alkali metal or alkaline earth metal oxides at high temperature to generate zirconate, and then obtains ZrO2 powder through acid washing, filtration, drying and other steps. In addition, the performance of ZrO2 can be regulated by doping different elements to meet the needs of different solid-state batteries.
The application of ZrO2 in solid-state batteries is mainly reflected in oxide solid electrolytes, such as lithium lanthanum zirconium oxide (LLZO) and lithium lanthanum zirconium titanium oxide (LLZTO), which exist in garnet-type crystal structures. In these solid electrolytes, ZrO2 occupies a very important proportion. For example, in the mass of LLZO before sintering, ZrO2 accounts for about 25%. In addition, in order to reduce the interface resistance in solid-state batteries and improve the efficiency of lithium ion migration, the positive and negative electrode materials usually need to be coated with materials such as LLZO. At the same time, oxide semi-solid batteries also need to construct a layer of ceramic diaphragm composed of materials such as LLZO, which further increases the amount of ZrO2 used in solid-state batteries.
With the continuous development of solid-state battery technology and the expansion of its application fields, the demand for ZrO2 as a solid electrolyte raw material will continue to grow. In the future, ZrO2 is expected to play a more important role in the field of solid-state batteries by further optimizing the preparation process, regulating performance and reducing costs. At the same time, with the continuous emergence of new solid-state electrolyte materials, ZrO2 will also face more intense competition and challenges. However, with its unique properties and broad application prospects, ZrO2 will still have an irreplaceable position in the field of solid-state batteries.
Inventory of 20 kinds of inorganic powders for plastics
Plastics are important products for production and daily life in today's society. The use of inorganic powders can effectively improve the physical and chemical properties of plastic products and enhance the performance of plastic products.
Wollastonite
Wollastonite is a natural calcium silicate (CaSiO3) with a light white needle-like structure. The aspect ratio (L/D) of processed wollastonite can reach more than 15/1. It is a fibrous inorganic reinforcing filler in plastics.
Talc
Talc has a flaky structure and has a significant reinforcing and modifying effect in plastics and rubber. It can improve the tensile strength, impact performance, creep resistance, heat resistance, tear resistance, etc. of plastic products.
Barium sulfate
The natural ore (barite) is crushed, washed and dried to obtain barite powder (also called heavy barium sulfate). Barium sulfate has excellent properties such as chemical stability, scratch resistance, heat resistance, high refractive index, outstanding sound insulation, heat preservation, and high gloss.
Mica
Mica is a layered aluminum silicate mineral with a unique structure. In addition to its reinforcing effect, it can also improve the air tightness, optical properties, and insulation properties of plastics.
Glass beads
Glass beads have the advantages of high temperature resistance and low thermal conductivity. When used to fill plastics, they can not only increase the wear resistance, pressure resistance, and flame retardancy of the material, but also its special spherical surface can improve the processing fluidity of the material; in addition, it has good surface gloss, which can increase the surface gloss of the product and reduce the adsorption of dirt on the surface.
Magnesium hydroxide
The chemical formula of magnesium hydroxide is Mg(OH)2. It can be prepared by chemical methods or obtained by crushing brucite ore. Magnesium hydroxide has a flame retardant effect. After surface modification, it can be filled into plastics to achieve the effect of smoke suppression.
Aluminum hydroxide
Aluminum hydroxide is a compound with the chemical formula Al(OH)x. It is used as a flame retardant, smoke suppressant and filler in PVC. Since it reduces the mechanical strength of thermoplastics when used in them, it is mostly used in thermosetting plastics.
Zeolite
Zeolite is a framework-shaped, hydrated alkali or alkaline earth metal aluminum silicate mineral. Its specific gravity, nanoporous structure, adsorption and chemical resistance can provide new development space for expanding the application of plastic products.
Kaolin
When used for filling and modification of plastics, it can improve the insulation strength of plastics. Without significantly reducing the elongation and impact strength, it can improve the tensile strength and modulus of thermoplastics with low glass transition temperatures. It can act as a nucleating agent for polypropylene, which is beneficial to improving the rigidity and strength of polypropylene. It has a significant infrared barrier effect.
Glass fiber (GF)
Glass fiber has high mechanical strength, elastic modulus, heat resistance and insulation, and is usually used to reinforce composite materials. GF can effectively make up for the shortcomings of biodegradable plastics, and can also significantly reduce the cost of products and expand the application range of biodegradable plastics.
Montmorillonite
Montmorillonite is a hydrophilic layered silicate material. Because of its nanometer size, it has a nano effect and can effectively improve the performance of polymers. Especially after modification, its application range is wider.
Other inorganic powders
Nano silicon dioxide has relatively stable chemical properties and a large specific surface area, which can effectively improve the strength, wear resistance and aging resistance of resin-based materials.
Rutile titanium dioxide can increase the reflectivity of light as a plastic filler and play the role of a light shielding agent.
Fly ash has the advantages of small specific gravity, high hardness and good fluidity.
Carbon black is generally used in the plastic industry for coloring, UV protection or conductivity.
Black inorganic minerals such as black talc and black calcite can partially replace carbon black. While fully utilizing mineral resources, the production cost has obvious advantages.
Using bentonite as an additive for degradable materials can replace starch and other chemical additives to reduce costs.
Halloysite has unique tubular nanostructures and good water dispersibility, different properties of inner and outer walls, high adsorption, biocompatibility and other unique and excellent physical and chemical properties.
Molybdenum disulfide is an inorganic compound composed of molybdenum and sulfur, and its chemical formula is MoS2.
Application of fumed silica powder materials
Since its introduction, fumed silica has attracted widespread attention due to its excellent properties. It is currently widely used in various industries, such as reinforcing rubber, adding it to plastics as a filler, adding it to inks as a thickener, adding it to cosmetics as a high-grade filler, etc. It is also used in coatings, paints, and adhesives. Fumed silica also shows excellent properties different from other materials in terms of magnetism, catalysis, melting point, etc., so it is also used as a functional additive. In recent years, nanotechnology has developed rapidly and achieved remarkable results. Fumed silica has a nanometer-scale particle size, is non-toxic and has high purity. Therefore, it has attracted the attention of researchers in some emerging fields and has made beneficial progress.
Application of fumed silica in the field of oxidative desulfurization
With the use of fossil fuels, the emission of sulfides is gradually increasing, leading to serious environmental pollution, destroying the ecosystem, and endangering human health. Therefore, deep desulfurization of fuel oil has gradually become an environmental problem that needs to be solved urgently. Hydrodesulfurization is a relatively developed technology that can remove most sulfides. However, the removal effect of heterocyclic sulfides and their derivatives is not good. Therefore, predecessors have studied and developed a variety of desulfurization technologies such as adsorption, extraction, and oxidative desulfurization (ODS). Among them, the ODS method has mild reaction conditions, simple operation process, and efficient desulfurization.
Application of fumed silica in food hygiene
A three-sided filler composed of fumed silica, iron and tea polyphenols, fumed silica fully increases the effective active quantity of iron and tea polyphenols, and significantly reduces Gram-positive Staphylococcus aureus and Gram-negative Staphylococcus. In addition, with the increase of loading, the antioxidant activity is affirmed, reaching a maximum value of 67%, and the specific migration limit of iron is lower than the limit applicable in the current food contact material regulations.
Application of fumed silica in the rubber field
Fumed silica is also commonly used in the preparation of silicone rubber. For room temperature vulcanized silicone rubber, fumed silica can not only improve its tensile strength, but also act as a thickener and thixotropic agent to control the performance of room temperature silicone rubber to a certain extent. Fumed silica can also be used to fill silicone resins, especially those used in the electronics field and silicone rubber mixing.
Application of fumed silica in ink and coating
In industry, people often add fumed silica to ink and coating to improve their rheological properties, and it also acts as a dispersant and anti-settling agent. Fumed silica is also added to some high-end coatings, such as marine ship coatings and industrial repair coatings, mainly due to the thixotropic and matting properties of fumed silica. In some high-solid content coatings with high environmental requirements, fumed silica is usually added to improve the thixotropic and dispersing properties of the coating. In industrial inks, an appropriate amount of fumed silica is generally added to adjust its rheological properties.
Application of fumed silica in the field of lithium batteries
Lithium metal soft-pack batteries have high energy density, light weight, lower cost and are more suitable for large-scale production. However, due to the characteristics of metallic lithium, the uncontrollable growth of Li dendrites during charging and discharging greatly hinders the cycle stability and commercialization of lithium batteries. Based on the nano characteristics and unique dielectric constant of fumed silica, the physical and chemical properties of lithium electrodes can be effectively improved, the growth of Li dendrites can be avoided, and the number of charge and discharge times of lithium batteries can be increased.
Application of fumed silica in mechanical polishing
Chemical mechanical polishing (CMP) is a leading technology for semiconductor device processing at this stage. CMP in the microelectronics field requires high slurry concentration and low impurity ion content. Both precipitated silica and fumed silica can meet this requirement, but precipitated silica is difficult to achieve high purity requirements. Fumed silica is the most ideal choice, and has low impurity ion content. It is easier to make the substrate material in the process flat for easy processing.
High value-added deep processing and utilization of bentonite
At present, the montmorillonite content of industrial bentonite primary processed products is generally 40%-65%, and it also contains certain clays (illite, kaolinite, halloysite, chlorite, allophane, etc.) and non-clays (zeolite, quartz, cristobalite, feldspar, calcite, pyrite, rock debris, iron oxides and organic matter).
The premise of high value-added deep processing and utilization of bentonite is to use mineral processing and purification technology to increase the montmorillonite content to more than 80%. The purified product is called montmorillonite.
Montmorillonite is a natural layered mineral with a huge specific surface area and non-uniform charge distribution. It has good water absorption, dispersion, dissociation, thixotropy, lubrication, adsorption, exchange and other abilities. It can be sold directly as a montmorillonite-based raw material, or it can be further inorganically or organically modified to produce catalyst carriers, inorganic gels, organic bentonite, organic/inorganic nanocomposites, lithium-based bentonite and other high value-added products.
1. Human medicinal montmorillonite
The application of montmorillonite in the pharmaceutical industry can be divided into two categories:
Medicinal raw materials: digestive tract mucosal protective agents, bactericidal and antibacterial agents, etc.
Medicinal excipients: excipients, suspending agents, filter agents, etc.
In medicine, montmorillonite stomach medicines are currently used in large quantities, and their preparations have been widely used in clinical practice. The montmorillonite stomach medicine preparations that have been developed successively include powders (high-purity montmorillonite, excipient-dispersed montmorillonite), granules, gels, suspensions, etc.
2. Montmorillonite for veterinary medicine and animal health care
Before using montmorillonite, it must be confirmed that it is non-toxic (arsenic, mercury, lead, and cristobalite do not exceed the standard). Its mechanism of curing and maintaining health for animals is similar to that of human stomach medicine, but it needs to be specially formulated and used for the prevention and treatment of diarrhea, dysentery, hemostasis, anti-inflammatory and other diseases in animals. It can remove mold and heavy metals in feed without toxic side effects; it also has a strong adsorption effect on heavy metals, harmful gases, bacteria, etc. in the digestive tract, thereby playing a role in animal health care.
3. Montmorillonite for feed ingredient enhancers
Montmorillonite has good adsorption, swelling, dispersion and lubricity, and can be used as an animal feed additive.
4. Montmorillonite for feed mildew inhibitors
Montmorillonite acts as a carrier in feed mildew inhibitors. Montmorillonite (mildew remover) is used to remove mycotoxins from feed and raw materials. Whether it is in vitro evaluation or animal testing, its effect is unquestionable.
5. Montmorillonite for dairy enhancers, etc.
Dairy farming is an important area of feed consumption. After adding montmorillonite to feed, the various macro and trace elements contained in it are components of enzymes, hormones and some bioactive substances in the cow's body, which can activate the activity of enzymes and hormones in the body, improve the function of the body's immune system, reduce feed consumption, enhance disease resistance and improve milk production performance.
6. Montmorillonite for cosmetics
Montmorillonite can effectively remove and absorb residual makeup, dirt impurities and excess oil in the skin texture, tighten overly coarse pores, accelerate the shedding and exfoliation of aging cells, dilute melanocytes, and improve skin color.
Surface modification of ceramic powders
Surface modification of ceramic powders is a key technology used to improve their performance in various applications, such as dispersibility, fluidity, compatibility with binders, and uniformity and density of the final product. Several main surface modification methods and their effects can be summarized.
Organic carboxylic acid esterification reaction
The esterification reaction between organic carboxylic acid and the hydroxyl groups on the surface of powders such as alumina can change the highly polar polyhydroxyl surface structure into a non-polar organic surface structure covered by long hydrocarbon chains, thereby eliminating the hard agglomeration between powders, reducing the internal friction during the pressing process, greatly improving the uniformity and density of ceramic green bodies and products, and significantly improving the strength of products.
Liquid phase chemical coating technology
The surface modification and surface coating of powders are used to improve the dispersibility of powders and change the phase structure and properties of powders. This includes the use of different polymer layers, such as polyethylene, polystyrene, and polymethyl methacrylate, which are polymerized on the surface of ultrafine ZrO2 and SiC powders by low-temperature plasma polymerization.
Use of stearic acid and adipic acid
The carboxyl groups in stearic acid and adipic acid undergo esterification reaction with the hydroxyl groups on the surface of nano zirconium oxide powder particles to form a monomolecular film on their surface, so that the surface-modified nano zirconium oxide powder is converted from polar to non-polar, while showing good flow properties.
Oxidation pretreatment
By oxidizing pretreatment of Si3N4 powder, a coating mainly composed of Si2N2O can be obtained on the surface. This treatment can significantly reduce the viscosity of the slurry, increase the amount of liquid phase during sintering, promote densification, and inhibit the nucleation of b-Si3N4.
High-energy ball milling method
Introducing nano-Al2O3 into ZrB2 through high-energy ball milling to form ZrB2-Al2O3 composite ceramic powder, and then performing organic functional modification can significantly improve the dispersibility of the powder in epoxy resin, and the modified composite material exhibits higher heat resistance.
Barium oxalate coprecipitation method
Selecting BaTiO3 powder produced by barium oxalate coprecipitation method as the matrix raw material, adding MgO to modify the surface of the powder particles can prevent grain growth, increase density, expand the firing temperature range and increase hardness.
Silane coupling agent coating modification
Using silane coupling agent KH-845-4 to coat and modify nano-Si3N4 ceramic powder can significantly improve the suspension stability, thermogravimetric, particle size distribution and other physical properties of the powder in the solvent.
Emulsion polymerization modification
Ultrafine ZrO2 ceramic powder is added to the polymer emulsion of methyl methacrylate (MMA) and styrene (ST) to prepare polymer-coated ceramic powder. This method can significantly improve the ability of powder to avoid agglomeration and is used for injection molding to prepare uniform and fluid ceramic injection materials.
How to crush superhard materials?
Superhard materials mainly refer to materials such as diamond, cubic boron nitride, corundum, silicon carbide, etc., which are much harder than other materials. Superhard materials are suitable for manufacturing tools for processing other materials, especially in processing hard materials. They have incomparable advantages and occupy an irreplaceable important position. For this reason, superhard materials have been widely used in industry. So how to achieve ultrafine grinding of superhard materials?
1. Traditional mechanical crushing method
The earliest crushing method is to crush hard materials into smaller particles through a series of mechanical equipment. The main equipment of this method includes jaw crusher, cone crusher, impact crusher, etc. The advantage of traditional mechanical crushing is that it can be applied to various materials and the cost is relatively low. However, the efficiency of mechanical crushing is not high, the degree of crushing of materials is difficult to accurately control, and it is easy to generate dust and noise.
2. High-pressure grinding method
High-pressure grinding method is a method of crushing hard materials by using high pressure to cause multiple collisions and frictions under the action of abrasive particles. Compared with traditional mechanical crushing methods, high-pressure grinding method can crush hard materials more efficiently, and can accurately control the degree of crushing, and the powder particles produced are uniform and fine. However, the cost of high-pressure grinding method is high, the operation is difficult, and professional technology and equipment are required.
3. Ultrasonic crushing
Ultrasonic crushing is a method of crushing material particles by using high-frequency vibration of ultrasound. This method is suitable for materials with high hardness and easy deformation, and has the advantages of high crushing efficiency, fine and uniform powder particles, and convenient operation. However, the degree of crushing of ultrasonic crushing is difficult to control, and the equipment requirements are very high.
Thoughts on improving grinding efficiency of mill
Factors that affect grinding efficiency include multiple aspects, such as whether the process design, layout, equipment selection, raw materials, process parameter selection, etc. are reasonable, whether the personnel training and operation level, system management are in place, etc. Generally speaking, the process design, layout, and equipment selection are fixed after the factory is built and are difficult to change. To achieve or even exceed the design goals, it depends on the management, operation control, and technical transformation. Such as raw material management; process parameter selection; mill structure adjustment; and the quality of operators, stability of control, etc.
1. Changes and responses to materials entering the mill
1.1 Particle size of materials entering the mill
The company's cement grinding system is a modified open-circuit mill with a pre-mill roller press. Due to the extrusion and crushing of the pre-mill roller press, and then the dispersion and classification, the particle size and grindability of the materials entering the mill have been greatly improved. The original particle size of the materials entering the mill was 20-40 mm, and after the transformation, most of the materials entering the mill were powder.
1.2 Grindability of materials entering the mill
Among the materials entering the mill, the most difficult to grind are clinkers. The clinker has a dense structure, good crystallization, and is not easy to grind.
1.3 Moisture content of materials entering the mill
Combined with expert analysis and multiple tests, our experience is that the comprehensive moisture content of materials entering the mill is controlled at about 2.0%.
1.4 Temperature of materials entering the mill
The temperature of materials entering the mill also has a great influence on the output of the mill and the quality of cement. Appropriate temperature of materials entering the mill plays a good drying role, and can also effectively control the temperature in the mill to ensure good grinding conditions and avoid "ball wrapping" and gypsum dehydration.
2. Adjustment of steel balls and steel forgings
Steel balls and steel forgings are still common in cement production as grinding media. In addition to material requirements, gradation and filling rate are two important indicators. Whether they are reasonable or not not only directly affects the quality of cement production, but also affects the power consumption of cement, which directly leads to changes in costs. With the implementation of new cement standards in my country and the improvement of concrete construction requirements, higher requirements are placed on cement fineness and particle gradation, and thus higher requirements are placed on cement grinding systems. Therefore, in cement production management, these two issues should be paid attention to.
3. Adjustment of mill structure
Cement mills are generally divided into 2 to 3 chambers. According to the company's situation, after adding the pre-mill roller pressing system, the particle size of the mill is greatly reduced, the crushing and coarse grinding functions of the first chamber are weakened, and the length of the second and third chambers is increased to enhance the grinding capacity. At the same time, the lining plate, the partition plate form, and the size of the grate hole are also adjusted accordingly, and a screening device is added inside the mill, which has a good effect. In addition, the mill bearing is changed from a sliding bearing to a rolling bearing, which reduces the starting current and working current, reduces the maintenance amount, and improves the operation rate. Due to the reduction in power usage, a certain amount of steel ball and steel forging load can be added, so the motor efficiency is improved, the useless work is reduced, and the hourly output can be increased, which improves the operation effect of the mill.
High-value application of silicon micro powder
Silicon micropowder is a non-toxic, odorless, pollution-free inorganic non-metallic material, made from natural quartz (SiO2) or fused quartz (amorphous SiO2 after natural quartz is melted at high temperature and cooled) through multiple processes such as crushing, ball milling (or vibration, air flow milling), flotation, acid washing and purification, and high-purity water treatment.
1 Application in copper-clad laminates
Silicon micropowder is a functional filler. When added to copper-clad laminates, it can improve the insulation, thermal conductivity, thermal stability, acid and alkali resistance (except HF), wear resistance, flame retardancy, bending strength and dimensional stability of the laminates, reduce the thermal expansion rate of the laminates, and improve the dielectric constant of the copper-clad laminates. At the same time, due to the abundant raw materials and low prices of silicon micropowder, it can reduce the cost of copper-clad laminates, so its application in the copper-clad laminate industry is becoming more and more extensive.
Ultrafine crystalline silicon powder
The average particle size of ultrafine silicon powder currently used in copper-clad laminates is 1-10 microns. As the substrates of electronic products develop towards ultra-thinness, fillers are required to have smaller particle sizes. In the future, copper-clad laminates will use ultrafine fillers with an average particle size of about 0.5-1 microns.
Fused silicon powder
Fused silicon powder is a powder made of natural quartz, which is melted at high temperature and cooled with amorphous silicon dioxide as the main raw material, and then processed by a unique process. Its molecular structure arrangement changes from ordered arrangement to disordered arrangement. Due to its high purity, it presents stable chemical properties such as extremely low linear expansion coefficient, good electromagnetic radiation, and chemical corrosion resistance, and is often used in the production of high-frequency copper-clad laminates.
Composite silicon micropowder
Composite silicon micropowder is a glass-phase silicon dioxide powder material made from natural quartz and other inorganic non-metallic minerals (such as calcium oxide, boron oxide, magnesium oxide, etc.) through compounding, melting, cooling, crushing, grinding, grading and other processes. The Mohs hardness of composite silicon micropowder is about 5, which is significantly lower than that of pure silicon micropowder.
Spherical silicon micropowder
Spherical silicon micropowder is a spherical silicon micropowder material with uniform particles, no sharp corners, small specific surface area, good fluidity, low stress and small bulk density, which is made of selected irregular angular silicon micropowder as raw material and processed by high temperature near melting and near spherical method.
Active silicon micropowder
Using active treated silicon micropowder as filler can significantly improve the compatibility of silicon micropowder and resin system, and further improve the moisture and heat resistance and reliability of copper clad board. At present, the domestic active silicon micropowder products are not ideal because they are only simply mixed with silicon coupling agents. The powder is easy to agglomerate when mixed with resin. Many foreign patents have proposed active treatment of silicon micropowder.
2 Application in high-end epoxy resin potting materials
Epoxy resin potting materials are widely used in the potting process of electronic device manufacturing. Potting is an operation process that uses potting materials to reasonably arrange, assemble, bond, connect, seal and protect the various parts of the electrical device according to the specified requirements. Its function is to strengthen the integrity of electronic devices, improve their resistance to external impact and vibration, improve the insulation between internal components and circuits of electronic devices, avoid direct exposure of internal components and circuits of electronic devices, and improve the waterproof, dustproof and moisture-proof performance of electronic devices.
3 Application in epoxy molding compound
Epoxy molding compound (EMC), also known as epoxy resin molding compound or epoxy molding compound, is a powder molding compound made of epoxy resin as the base resin, high-performance phenolic resin as the curing agent, silicon micropowder and other fillers, and a variety of additives. 97% of the global integrated circuit (IC) packaging materials use epoxy molding compound (EMC). The molding process is to extrude EMC into a special mold cavity by transfer molding, embed the semiconductor chip in it, and complete cross-linking and curing molding to form a semiconductor device with a certain structural appearance. In the composition of EMC, silicon micropowder is the most used filler, accounting for 70% to 90% of the weight of epoxy molding compound.
Quality requirements for quartz sand for various types of glass
Silicon dioxide is the main structure of glass, which can ensure that the glass has high strength and good chemical stability. Therefore, quartz sand is the most important industrial mineral raw material in the glass industry, including flat glass, daily glass, ultra-white glass, photovoltaic glass, quartz glass, etc.
The quality requirements of quartz sand in the glass industry are mainly reflected in three aspects: chemical composition, stability, and particle size. Different glass products have different quality requirements for quartz sand.
1. Flat glass
Different flat glass downstream markets have different requirements for quartz sand indicators. According to the chemical composition and particle size, the quartz sand used in the entire flat glass industry can be divided into two types: Class I and Class II. Class I has a low Al2O3 content, and Class II has a high Al2O3 content.
2. Daily glass
Daily glass products mainly include bottle glass, utensil glass, instrument glass and pharmaceutical glass, which provide various packaging and meet social consumption needs for industries such as food, brewing, beverages and medicine. Quartz sand is the raw material with the largest amount of daily glass batches. The melting temperature of quartz sand is as high as about 1730℃, and the particle size of quartz has the greatest impact on the formation of glass.
In actual production, quartz particles should be angular in shape, with a large surface area, and the batch is not easy to stratify. The particle size range is 60-140 mesh.
3. Ultra-white glass
Ultra-white glass is a new material glass with extremely high light transmittance (light transmittance ≥ 91.5%), iron impurity content basically controlled between 100~150ppm and extremely transparent appearance. Other names for ultra-white glass are low-iron glass and high-transparency glass.
The raw materials for ultra-white glass production mainly include quartz sand, feldspar, dolomite, limestone, heavy alkali, aluminum hydroxide, sodium sulfate, sodium pyroantimonate and antimony trioxide, etc., and the requirements for the percentage of various raw materials are very strict. In order to meet the use requirements of ultra-white glass, the industry has strict regulations on the composition of ultra-white glass.
4. Photovoltaic glass
Photovoltaic glass is mainly installed on the outermost layer of photovoltaic modules to block the influence of moisture and corrosive gases, and protect the cells and electrodes. Compared with ordinary glass, photovoltaic glass needs to have low iron content, high light transmittance, impact resistance, corrosion resistance, high temperature resistance and other characteristics. Ultra-white float glass and ultra-white rolled glass can meet the above requirements. Among them, ultra-white rolled glass is used for crystalline silicon cells and is the mainstream product of photovoltaic glass, while ultra-white float glass is mostly used for thin-film cells.
The iron ions in quartz sand are easy to dye. In order to ensure the high solar transmittance of the original glass, the iron content of photovoltaic glass is required to be lower than that of ordinary glass. Low-iron quartz sand with high silicon purity and low impurity content must be used.
5. Quartz glass
Quartz glass is known as the "crown" of glass materials. It is a glass with SiO2 as a single component and has superb mechanical, thermal, optical and electrical properties. It plays an irreplaceable role in semiconductors, optical devices, optical communications, solar energy and other industries. High-purity quartz sand is currently the main raw material for replacing crystal ore and melting quartz glass. Quartz glass produced by electric melting process and gas refining process uses high-purity quartz sand as raw material.