The use of tungsten metal: the world's exploitation of tungsten ore, about 50% for high-quality steel smelting, about 35% for the production of hard steel, about 10% for tungsten filament, Tungsten Metals about 5% other for other use. According to tungsten waste recycling experts understand that tungsten can make firearms, rocket push, into the nozzle, cutting metal blade, drill, super hard mold, drawing die, etc., tungsten is widely used, involving mining, metallurgy, Construction, transportation, electronics, chemicals, light industry, textile, military, aerospace, science and technology, various industrial fields.
Tungsten metal main purposes:
1, processing with a knife head, lighting equipment with a variety of tungsten wire and thermal conductivity;
2, manufacturing high-level car crankshaft, cylinder of the ingredients, casting a variety of special steel ingredients;
3, widely used in firearms, artillery, rockets, satellites, aircraft, ship manufacturing.
Tungsten is a non-ferrous metal and is also an important strategic metal, tungsten ore in ancient times known as "heavy stone". The content of tungsten in the crust is 0.001%. Tungsten Metals There are 20 kinds of tungsten-containing minerals found. The tungsten deposits are generally formed by the activity of the granitic magma. After smelting the tungsten is silver and shiny metal, melting point is extremely high hardness. Tungsten Metals Tungsten is a rare, high melting point metal belonging to the VIB family of the sixth cycle (second long period) in the periodic table. Tungsten is a silver-white metal, shape like steel.
The high melting point of tungsten, the vapor pressure is very low, the evaporation rate is also small. Tungsten chemical properties are very stable, at room temperature does not react with air and water, insoluble in hydrochloric acid, sulfuric acid, nitric acid and alkaline solution. Tungsten Metals Wang water can only make its surface oxidation, soluble in nitric acid and hydrofluoric acid mixture. High temperature with chlorine, bromine, iodine, carbon, nitrogen, sulfur and other combinations, but not with hydrogen.
Tungsten metal other alloys - tungsten titanium alloy, tungsten chromium cobalt alloy, etc., are also well-known carbide. The chemical properties of tungsten is very stable, Tungsten Metals even in the case of heating, it will not with hydrochloric acid, sulfuric acid, or even not dissolved in the water - in the aqua regia, tungsten is just slow oxidation of the surface only. Only corrosive strong hydrofluoric acid and nitric acid mixture, can dissolve tungsten. Tungsten has many compounds, of which tungsten iodide, tungsten bromide can be used to make new light source; Tungsten Metals sodium tungstate can be used to make fire cloth; lead tungstate can be used as white pigment, tungsten oxide is yellow pigment. In the crust, the tungsten content is four hundred thousandths. China's tungsten reserves, accounting for the world's first! Which in Jiangxi Geshan mountains possession of the most, in addition to Guangxi, Guangdong, Hunan and other places are also rich in tungsten.
Tungsten metal is the highest melting point of metal (3410 ° C), at the same time with high strength, high hardness, low resistivity characteristics. Tungsten metal high temperature, impact resistance, wear resistance, good thermal stability, to ensure the stability of the device under high temperature conditions, MEMS devices are well-made processing and manufacturing materials, Tungsten Metals especially for high temperature and other harsh or extreme surroundings. Traditional tungsten materials use physical or chemical deposition method to form thin films, but due to process constraints and stress and other reasons, the film thickness is generally not more than 2 microns, affecting the device design and manufacturing. If devices such as MEMS switches, MEMS resonators, MEMS probes, micro EDM electrodes can be fabricated using tungsten metal materials as structural materials instead of conventional monocrystalline silicon materials, these devices will have more Superior electrical, mechanical and high temperature and other characteristics. Tungsten Metals Tungsten metal is the main material of microelectronics chip test probe. With the reduction of chip pitch, the probe and probe card also need to be miniaturized by the new micro-processing method, compared with the current single-crystal silicon microprobe Card), tungsten metal material formed micro-probe (card) with high hardness, low wear rate, low resistance, Tungsten Metals high reliability advantages. Due to the high density and high hardness of tungsten metal, the traditional reactive ion etching process has very low etch rate and lateral erosion. It can not realize the deep depth and high aspect ratio in relatively short time. Corrosion, can not meet the manufacturing requirements of MEMS devices. Therefore, Tungsten Metals the current application of tungsten metal is in the integrated circuit process, through physical or chemical deposition method to prepare a layer of less than 2 microns thin film, and then use the traditional reactive ion etching process to process them to prepare the device Such as metal grids, metal interconnections, metal diodes, etc., the use of etching gas or gas combination involving CF4, CF4 + 02, Cl2, Cl2 + 02, SF6, SF6 + 02, NF3, CCl4 + 02, etc. (PEI), reactive plasma etching (RIE), electron cyclotron resonance plasma etching (ECR), etc., due to the relatively low plasma density (less than IOici-IO12cnT3), low energy, The resulting etch rate is generally much less than 1 micron per minute. At present, there are no related reports using tungsten metal materials as the main structure of the preparation of MEMS devices, and the existing thin film tungsten material etching process rate is generally low, anisotropy is poor, Tungsten Metals become the main bottleneck. Applicable to the processing of tungsten metal materials, can achieve high rate, high aspect ratio of the etching process has not been reported.