What is the Trend of Ta & Nb Market?

The atomic sequences of tantalum (Ta) and niobium (Nb) are 73 and 41, respectively, both of which are located in the VB family of excessive elements. They are often symbiotic in nature and are important refractory rare metals. They look like steel, with off-white luster, and the powder is dark gray. They have excellent properties, including a high melting point, high boiling point, low vapor pressure, good cold workability, high chemical stability, strong resistance to liquid metal and acid and alkali corrosion, and high dielectric constant of the surface oxide film, etc.

ta trend

Tantalum and niobium metals and their compounds and alloys are important functional materials, which has important applications in the technical fields of electronics, steel, metallurgy, chemicals, hard alloys, atomic energy, aerospace, and other industrial sectors as well as strategic weapons, superconducting technology, scientific research, medical devices and so on.

Applications of tantalum and niobium

Tantalum and niobium are similar in nature and can be replaced in many application areas. However, their respective characteristics have led to the use of tantalum in industries such as electronics, metallurgy, chemicals, and hard alloys.

Electrolytic capacitors made of tantalum metals in the electronics industry have outstanding characteristics such as large capacitance, small leakage current, good stability, high reliability, good pressure resistance, long life, and small volume. They are widely used in national defense, aviation and aerospace, electronic computers, high-end civilian electrical appliances, and electronic circuits of various electronic instruments. Niobium is used in industrial-grade superconducting technology such as steel, ceramics, and nuclear energy.

In today’s world, about 65% of the total tantalum is used in the electronics industry, and about 87% of the total niobium is used in the steel industry. With the advancement of technology, the application fields of tantalum and niobium and their alloys and processed materials will continue to expand.

Tantalum can store and release energy, which is indispensable in the electronics industry, so tantalum capacitors consume more than half of the world’s mine production.

The tantalum-based components can be made very small, and other chemical elements cannot be used as substitutes without degrading the performance of the electronic device, so tantalum is almost ubiquitous as a component application, such as mobile phones, a hard disks, and a hearing aid.

In the chemical industry, the corrosion resistance of tantalum is very good and it is used as a lining for pipelines and tanks. Tantalum carbide has a high hardness and is an ideal material for manufacturing cutting tools, and tantalum oxide can increase the refractive index of glass lenses.

Current supply and demand situation

Before the end of 2011, the industry was generally operating in a benign environment. The front end of tantalum niobium production has a large space, the intermediate wet smelting and fire smelting also have a certain profit, and the back end high specific volume of tantalum powder and tantalum wire production and sales market also has a large operation space. However, since the second half of 2012, with the emergence of the global financial crisis, such applications as tantalum niobium are relatively narrow and the consumer sector has been greatly affected by the high-end electronic products industry.

The trend of the tantalum niobium market

At present, the production in the tantalum niobium industry is mainly based on wet smelting and pyrometallurgical smelting. The products produced are mainly potassium fluoroantimonate, antimony oxide, antimony oxide, antimony carbide, antimony wire, metallurgical grade tantalum powder, and some coffin materials.

At present, the domestic demand for tantalum niobium is 800~1000 tons, and the national production capacity is about 140~150 tons. Most of the rest of the raw materials are all dependent on African imports.

Most of the exported antimony mines in Africa are also known as “African blood mines”, which refer to war-plunging low-cost minerals that are arbitrarily harvested and dug in the African region at the expense of polluting the environment and destroying resources. African mines are affected by the instability of the regional political and economic environment and have greater volatility. Its products contain high levels of unfavorable elements such as antimony, uranium, and thorium, which have certain adverse effects on product quality and environmental protection requirements of downstream products; Moreover, the delivery period of the mine is long and the safety cannot be fully guaranteed. To this end, the International Electron Association has classified it as a source of minerals that are not allowed to enter the normal market.

Stanford Advanced Materials supplies high-quality tantalum niobium products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

Is tantalum Toxic?

Tantalum is a shiny, silvery metal that is soft when is pure. It is almost immune to chemical attacks at temperatures below 150℃. Tantalum is virtually resistant to corrosion due to an oxide film on its surface.

Applications of tantalum

Tantalum is used to manufacture surgical implants, capacitors, aircraft engines, and alloys. It is used to produce high-temperature devices because of its high melting point. The element also has application in the chemical industry because of its good corrosion resistance. It is used to manufacture refractive index glass, electron tubes, and alloys for missiles, nuclear reactors, chemical equipment, and jet engines.

However, the element is rarely added to alloys because it makes some metals more brittle. Tantalum is used to manufacture tubes because it forms oxides and nitrides that create the vacuum. In addition, it is used to manufacture special optical glasses, non-ferrous alloys for aerospace and nuclear applications, metallurgical and chemical processing equipment, high-voltage surge arresters, and more. It is also used to make circuitry for devices and computers, electrolytic capacitors, and tantalum compounds and alloys. Glass-line equipment is also manufactured. Its compounds are used to produce clips, mesh, surgical equipment, and machinery.

solid tantalum chip capacitors

The harm of tantalum

Tantalum powder is not as serious as other metals (zirconium, titanium, etc.), but it has the risk of fire and explosion.

Tantalum-related jobs often carry the risk of burns, electric shocks, eyes, and trauma. The refining process involves toxic and dangerous chemicals such as hydrogen fluoride, sodium, and organic solvents.

Toxicity

Both tantalum oxide and tantalum metal have low systemic toxicity, which may be due to their poor solubility. However, there are also skin, eye, and respiratory hazards. In alloys of cobalt, tungsten, and niobium, tantalum is considered to be the cause of pneumoconiosis and skin damage caused by hard metal dust.

Tantalum hydroxide has no toxic effect on chicken embryo, and intraperitoneal injection of tantalum oxide has no toxic effect on rats. However, when tantalum chloride has an LD50 of 38mg/kg(Ta), the compound salt K2TaF7 is about one-fourth toxic.

Safety precautions

In most operations, general ventilation can maintain the dust concentration of tantalum and its compounds below the exposure limit. Flame, arc, and spark should be avoided in the area where tantalum powder is handled. If workers are regularly exposed to dust concentrations close to the critical value, regular physical examinations should be conducted, with emphasis on lung function. For operations containing tantalum fluoride and hydrogen fluoride, precautions applicable to these compounds should be followed.

Tantalum bromide (TaBr5), tantalum chloride (TaCl5), and tantalum fluoride (TaF5) shall be stored in a clearly labeled and cool, ventilated place away from compounds affected by acid or acid smoke, and the persons concerned should be reminded of the danger.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

Overview of the Properties of Tantalum Compounds

Tantalum oxide

The most useful tantalum oxide is tantalum pentaoxide (Ta2O5). Ta2O5 is white fine crystal powder, tasteless and odorless, with a specific gravity of 8.71g/cm3 and a melting point of 1870℃. Tantalum is amphoteric but apparently acidic, insoluble in water, most acids, and bases, but slowly dissolved in hot hydrofluoric and peroxy acids.

tantalum oxide

Ta2O5 has both α and βvariants, and its transition temperature is 1320℃, beyond which Ta2O5 turns white to gray. Different oxides have different crystal structures, so their lattice constants, densities, and other properties are obviously different. It is known that amorphous Ta2O5 begins to crystallize at 500℃ to form a low-temperature crystal (T type), converts to a temperature crystal (M type) at 830℃, and forms a high-temperature crystal (H type) at more than 830℃.

Tantalum halide

In tantalum halides, halogens in high-priced pentahalides are more easily replaced by oxygen to form stable halogen oxides. Most of the halogens of tantalum are volatile compounds, among which fluoride is well soluble in water and only partially hydrolyzed.

Tantalum(V) chloride (TaCl5) is a white powder and yellow when it is not pure. It has a melting point of 220℃, a boiling point of 223℃-239℃, and a specific gravity of 3.68g/cm3. It is volatile and has strong moisture absorption. It is unstable at high temperatures and decomposes to form metal tantalum at vacuum temperatures above 800℃. In addition to the high-priced TaCl5, the low-priced chlorides of tantalum include TaCl4, TaCl3, and TaCl2, which are volatile substances.

Tantalum bromide (TaBr5) is an orange crystal, soluble in water and hydrolyzed, soluble in methanol, ethanol, and CCl4, and soluble in aniline and liquid ammonia for reactions. Tantalum iodide (TaI5) is a black crystal that can be heated to sublimate without decomposition and readily hydrolyzes in moist air, releasing hydrogen iodide.

Tantalum carbide

Ta2C and tantalum carbide (TaC) are the main carbides of tantalum, and Ta2C has both alpha -Ta2C and beta -Ta2C isomers. TaC is a dark brown powder with a melting point of 3880℃, a boiling point of 5500℃ and a density of 14.4g/cm3. It has good chemical stability and can only be dissolved in mixed solutions of nitric acid and hydrofluoric acid. The carbide of tantalum is not easy to be oxidized in the air when the temperature is lower than 1000 ~ 1100℃. Nitrogen compounds are readily formed by the action of nitrogen or ammonia.

Tantalum hydride

Tantalum hydrides are very stable at room temperature in the air. Hydrogen is released by decomposition when heated to 1000 ~ 1200℃ under a high vacuum. Below 350℃, tantalum almost has no interaction with hydrogen, and the reaction speed increases with the increase of temperature. At a certain temperature and pressure, the maximum hydrogen content in tantalum hydride corresponds to H/Ta of 0.02 ~ 0.08(TaH0.2 ~ TaH0.8).

Tantalum nitride

There are three kinds of tantalum nitride: TaN, Ta2N, and Ta3N5. Tantalum nitrite is a bluish-gray powder with a melting point of 2980 ~ 3090℃ and a density of 14.4g/cm3. It is insoluble in nitric acid, hydrofluoric acid, and sulfuric acid, but soluble in hot alkaline solution and releases ammonia or nitrogen. Tantalum nitride generates oxides when heated in air, releasing nitrogen.

Tantalum selenite

TaSe2, its resistivity is 2.23 x 10-3 Ω. Cm, with the relative friction coefficient of 0.08 in the air at room temperature, the oxidation temperature of 600 ℃ in air, and the decomposition temperature of 900 ℃ in a vacuum.

Tantalum silicone

The main silicide of tantalum is TaSi2, and there are also some other compounds such as Ta2Si and Ta5Si3. Ta2Si has a melting point of 2200 ℃, a density of 8.83 g/cm3 and a resistance of 8.5 Ω. Cm. It is not eroded by mineral acids, but can be decomposed by hydrofluoric acid, and can be completely decomposed by molten Na2CO3 and NaOH.

Tantalate

Ta2O5 can be fused with oxides, hydroxides, or carbonates of more than 50 elements from all 8 groups in the periodic table of chemical elements to form various complex types of tantalates, which may be expressed in the following general formula: xMeO•yTa2O5 (Me = alkali metal).

Almost all alkali tantalates have a high degree of polymerization in aqueous solution and are insoluble compounds in water solution. Alkali tantalate can be reduced by hydrogen: 2MeTaO3+H2=Me2O+2TaO2+H2O, with a reaction temperature of 600~700℃. Except for alkali tantalates, most tantalates are insoluble in water.

Most tantalate crystals (such as lithium tantalate) are ferroelectric. They belong to the category of thermoelectric devices that have spontaneous polarization. Their polarization value is related to electric field voltage and has Curie temperature. Tantalum ferroelectric materials also have the characteristics of voltage, electro-optic and nonlinear optics. Some tantalates are semiconductor materials with narrow channels and are important materials for manufacturing electronic industrial components.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Why Do Electrolytic Capacitors Explode?

If you want to know why the electrolytic capacitor explodes, first you have to know what the electrolytic capacitor is. An electrolytic capacitor is a kind of capacitance. The metal foil is the positive electrode (aluminum foil or tantalum foil), and the oxide film (aluminum oxide or tantalum oxide), which is closely attached to the metal, is the dielectric. The cathode consists of conductive material, electrolyte (which can be liquid or solid), and other materials. Because the electrolyte is the main part of the cathode, the electrolytic capacitor is hence named. At the same time, the capacitance of the electrolytic capacitor cannot be connected wrongly.

capacitors explode

Tantalum electrolytic capacitor mainly consists of sintering solid, foil winding solid, sintering liquid, and so on. The sintered solids account for more than 95% of the current production and are mainly composed of non-metallic sealed resin.

The aluminum electrolytic capacitor can be divided into four types: the lead type aluminum electrolytic capacitor; Horn type aluminum electrolytic capacitor; Bolted aluminum electrolytic capacitor; Solid aluminum electrolytic capacitor.

The possible reasons for the capacitor explosion are as follows:

  1. The breakdown of the internal components of the capacitor is mainly due to the poor manufacturing process.
  2. The capacitor is damaged by insulation to the shell. The high voltage side of the capacitor is made of a thin steel sheet. If the manufacturing process is poor, the edge is uneven with burr or serious bend. The tip is prone to corona, and the corona causes the breakdown of oil, the expansion of the case and the drop of oil. In addition, when the cover is closed, if the welding time is too long, the internal insulation burns and produces oil and gas, causing the voltage to drop greatly and damage.
  3. Poor sealing and oil leakage. The insulation resistance is reduced due to the poor sealing of the assembly casing. Or the oil spill caused the oil surface to drop, resulting in the extreme shell direction discharge or component breakdown.
  4. The belly and the inside dissociate. Due to the internal corona, breakdown discharge, and serious dissociation, under the action of overvoltage, the starting free voltage of the element is reduced to the working electric field intensity. This causes the physical, chemical and electrical effects to accelerate the aging and decomposition of the insulation, producing gas and forming a vicious circle, the pressure of the case is increased, causing the drum to explode
  5. A capacitor explodes with an electric charge. All capacitors with rated voltages are forbidden to be charged. Each time the capacitor bank recloses, the capacitor must be discharged for 3min after the switch is disconnected. Otherwise, the voltage polarity of the closing moment may be caused by the opposite polarity of the residual charge on the capacitor. For this purpose, a capacitor bank with a capacity of more than 160kvar is generally required, and automatic tripping device should be installed when there is no pressure. And the capacitor bank switches are not allowed to install automatic reclosing.

In addition, it may be caused by high temperature, poor ventilation, high operating voltage, excessive voltage harmonic component or operating overvoltage, etc.

Stanford Advanced Materials (SAM) is a leading supplier and manufacturer of high-quality capacitor grade tantalum powder and tantalum wire with competitive price and great delivery time. Please visit http://www.samaterials.com for more information.

Protective Coatings Application of Tantalum Oxide

Tantalum oxide is shown to be chemically very robust. Reactively sputtered tantalum oxide thin films have been investigated as a protective coating for aggressive media exposed sensors.

The step coverage of the sputter-deposited amorphous tantalum oxide is reasonable, but metallization lines are hard to cover. Sputtered tantalum oxide exhibits high dielectric strength and the pinhole density for 0.5 pm thick films is below 3 cm.

tantalum oxide

Applying protective coatings as a solution to this sensor concept requires a number of properties for the coating to fulfill, a short list includes:

  1. Corrosion resistance: the maximum allowable thickness of the coating and minimum required lifetime sets the upper limit of the etch rate in the media of interest.
  2. Low residual stress in small thickness: to limit the reduction of sensitivity due to stiffness changes in the membrane.
  3. Step coverage: poor coverage over interconnects and contact windows are sites where degradation of the sensor will initiate.
  4. Pinhole density: usually no pinholes are allowed in the exposed area of the sensor. Etchants will penetrate the coating and degrade electrically active components or under etch, eventually resulting in an undesired lift-off of the coating. In case the pinholes are due to particulate contamination, the pinholes may be eliminated by growing thicker films.
  5. Electrical properties: a dielectric film is required to insulate electrical components on the sensor from electrically conducting media.
  6. Patternable: in many cases, it is desired to pattern the protective coating for access to bond pads. Patterning in a batch process, such as wet etching, is preferred.
  7. Double-sided deposition for protection of both sides of the differential pressure sensor.
  8. Coverage of sharp corners: a conformal coating is required.
  9. Coverage of deep cavities: a conformal coating is required down to the bottom of the cavity.

The use of tantalum, tantalum alloys, and tantalum oxide has already been suggested for sensor purposes. Besides, tantalum is used in chemical processing equipment because it is extremely stable. The reason for this is the formation of a thin amorphous tantalum oxide layer at the surface, which is chemically very inert.

Deposition of tantalum and its oxides and nitrides can be done by physical vapor deposition, chemical vapor deposition, or by thermal oxidation. This makes the use of these materials very flexible.

Please visit http://www.samaterials.com for more information.

What Are the Advantages of Tantalum Electrolytic Capacitors

Tantalum electrolytic capacitors are widely used in communications, computers, aerospace, and military, as well as advanced electronic systems, portable digital products, and other fields.

tantalum electrolytic capacitors

Tantalum electrolytic capacitor is made of tantalum (Ta) metal as anode material, which can be divided into foil type and tantalum powder sintered type according to different anode structures. Among tantalum powder sintered tantalum capacitors, there are tantalum capacitors with solid electrolytes and tantalum capacitors with non-solid electrolytes due to different electrolytes. The shell of tantalum electrolytic capacitors is marked with CA, but the symbol in the circuit is the same as that of other electrolytic capacitors. Compared with aluminum electrolytic capacitors, tantalum electrolytic capacitors have the following advantages.

Tantalum-Electrolytic-Capacitors
Tantalum-Electrolytic-Capacitors

Small volume

Because tantalum electrolytic capacitors are made of very fine tantalum powder, and the dielectric constant of the tantalum oxide film is higher than that of the alumina oxide film, the capacitance per unit volume of tantalum electrolytic capacitors is large.

Wide temperature range for use

Tantalum electrolytic capacitors commonly can work normally at the temperature of -50 ℃~100 ℃. Although the aluminum electrolytic capacitor can also work in this range, its electrical performance is not as good as that of the tantalum electrolytic capacitor.

Long life, high insulation resistance, and small leakage current

Tantalum oxide film in tantalum electrolytic capacitors is not only corrosion-resistant but also can maintain good performance for a long time.

Good impedance frequency

For capacitors with poor frequency characteristics, the capacitance will drop sharply and the loss (tg delta) will also rise sharply when the working frequency is high. However, solid tantalum electrolytic capacitors can operate above 50kHz. When the frequency of the tantalum electrolytic capacitor increases, the capacity will also decrease but by a small margin. The data show that the tantalum electrolytic capacitor capacity decreases by less than 20% at 10kHz, while the aluminum electrolytic capacitor capacity decreases by more than 40%.

capacitor-tantalum

High reliability

Tantalum oxide film has stable chemical properties. In addition, Ta2O5 anode substrate of tantalum can withstand strong acid and pressure, so it can use a liquid electrolyte with low resistivity of solid or acid. In this way, tantalum electrolytic capacitors have less loss than aluminum electrolytic capacitors and have good temperature stability.

Chip tantalum electrolytic capacitors are made of highly pure and extremely small homogeneous particles, which are characterized by small size, large capacity, and high frequency. In recent years, chip tantalum electrolytic capacitors have been widely used in mobile phones, DVDs and other consumer electronic products.

Please visit http://www.samaterials.com for more information.

How is Tantalum Metal Used in Various Industries Made?

Tantalum is a metal element with the element symbol of Ta, an atomic number of 73, a density of 16.68g/cm, and a melting point of 2980 DEG C. Pure tantalum with blue color and excellent ductility can be rolled into a very thin plate in the cold state without intermediate annealing.

tantalum powder

Tantalum has a series of excellent properties such as high melting point, low vapor pressure, and cold processing performance, high chemical stability, anti-corrosion ability, constant liquid metal oxide film, which has important applications in electronics, metallurgy, chemical industry, aerospace, medical health, and scientific research and other high-tech fields.

Discovery history

In the middle of the Seventeenth Century, a heavy black mineral was found in North America and was sent to the British Museum. After about 150 years, until 1801, the British chemist C.Hatchett accepted the analysis task of the ore in the British Museum, discovered a new element, and named it columbium, which is to commemorate the earliest discovered mineral areas — Columbia.

In 1802, when the Swedish chemist A.G.Ekaberg analyzed a mineral in Scandinavia, making their acid fluoride salt after recrystallization, leading to the discovery of the new element, he named the element tantalum referred to in Greek mythology, Jose Tantalus, the son of God’s name.

Due to the nature of columbium and tantalum being very similar, people once thought that they are the same kind of elements. In 1809, the British chemist William Hyde Wollaston compared tantalum and Columbium oxide, although different density value, he believes that the two are identical materials.

In 1844, the German chemist Heinrich Rose dismissed the conclusion that tantalum and Columbium are the same element, and identified that they are two different elements by chemical methods. He named them “Niobium” and “Pelopium”.

In 1864, Christian Wilhelm Blomstrand, and Louis Joseph Troost clearly demonstrated that tantalum and niobium are two different chemical elements, and determine the chemical formula of some related compounds. The early tantalum metal has more impurities. Werner von Bolton was first made pure tantalum metal in 1903.

Scientists first extract tantalum from niobium with the method of hierarchical crystallization, which is found by de Marinilla in 1866. Today, scientists are using a solvent extraction method for the solution containing fluoride.

Preparation technology

The preparation of tantalum is the process of reducing pure tantalum compounds to metal tantalum. The raw materials are five tantalum oxide, tantalum chloride, five tantalum fluoride, and fluoride (such as K2TaF7,). The reducing agent is sodium, magnesium, other active metals, and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so it is powder or spongy metal after reduction. It is necessary to further smelting or refining, in order to get dense metal.

The tantalum preparation methods are sodium thermal reduction, carbon thermal reduction, and molten salt electrolysis. Sodium thermal reduction of potassium tantalate is the most widely used method of tantalum production in the world.

The tantalum powder has a complex shape and a large specific surface area. Carbon thermal reduction of five oxidation of tantalum has been an industrial method for the production of tantalum, but because the purity of the product is not high enough, is not as widely used as the sodium reduction method. The molten salt electrolysis method is divided into two ways: electrolyte electrolysis and oxygen-free electrolyte electrolysis. Molten salt electrolysis can only produce metallurgical grade tantalum powder. Five hydrogen fluoride reduction is considered to be one of the most promising methods for tantalum production, but it has not been used in industrial production because of the high requirements of equipment material and environmental protection.

The majority of tantalum powder is directly used for tantalum capacitors in the electronic manufacturing industry, so the tantalum milling process, such as the preparation of tantalum metal is also from tantalum and tantalum powder by vacuum heat treatment, capacitor grade tantalum powder hydrogenation method category.

Tantalum-Powder
Tantalum-Powder

Production of tantalum powder

Sodium metal thermal reduction method is an important method for the production of tantalum powder, which is the main method of industrial production of tantalum powder (including metallurgical Ta powder). The particle shape of metal tantalum powder with the large surface area is complex, which is suitable for anode material for tantalum electrolytic capacitors by electron beam melting and vacuum arc melting of tantalum or tantalum sintered in vacuum refining, then the high purity tantalum rod made and then processed into a variety of tantalum.

Since the 1970s, it has been widely used to increase the specific capacitance of tantalum powder. The commonly used doping agent is phosphate, which can be mixed before or after the crystallization of potassium fluoride and can be added before the vacuum heat treatment of tantalum powder. The doping can prevent the sintering of tantalum powder during the sintering of the tantalum anode block, thus avoiding the reduction of the specific surface area of the tantalum anode block. We can remove oxides from metal sodium with the metal-ceramic filter or cold trap method.

The process of reduction of potassium and sodium fluoride in an inert atmosphere at 1153 ~ 1173K temperature and the reduction products are metal tantalum powder, potassium fluoride, sodium fluoride, and diluent which are not involved in the reaction.

Before the 1950s, the solid metal sodium and potassium fluorotantalate layer was placed in the reactor of bomb explosion reduction reaction, although the product of tantalum powder is fine particle size, large surface area, oxygen, and carbon content is high, no practical value.

With tantalum capacitors being small and micro, the corresponding need to adopt more surface area tantalum powder, mainly used in the liquid reduction, mainly supplemented by mixing sodium, doping technology, the volume rate of tantalum powder increased to 1000uF – V yield every year.

tantalum-capacitors
tantalum-capacitors

The fluoride was removed by dipping, and then washed with HCl18% and HF1% solution at 1 2H for 363K, then washed with pure water and dried at 353K temperature. For the preparation of capacitor grade tantalum powder, tantalum powder should be the original size distribution, vacuum heat treatment (see tantalum powder vacuum heat treatment), crushing and screening and modulation post-processing, if necessary, will also increase the magnesium reduction deoxygenation, pickling, washing and plastic processing, in order to obtain high quality and low and high specific capacitance of capacitor grade tantalum powder.

It is expected that the continuous improvement and development of tantalum powder produced by sodium reduction is the result of the miniaturization, miniaturization, and cost reduction of electronic products. Since the 1960s, the specific capacitance of tantalum powder has been increasing, and the capacitance ratio of tantalum powder has reached 22000~26000uF•V/g in the United States, Japan, Germany, and other countries.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

An Overview of Tantalum Sputtering Target Material

Tantalum sputtering target material is a chip of tantalum obtained by pressure processing. It has high chemical purity, small grain size, as well as good recrystallized structure and consistency of three axes. Tantalum sputtering target is mainly used in optical fiber, the semiconductor chip and integrated circuit sputtering deposition film, as well as in cathode sputtering coating, high vacuum suction active material, etc., which is an important material for thin film technology.

Classification of the tantalum target

According to the application field, it can be divided into optical tantalum target and semiconductor tantalum target.

Tantalum-Sputtering-Target
Tantalum-Sputtering-Target

The performance index of the tantalum target

  • Purity

Metal impurities do not affect the sputtering process but affect the life of tantalum film, and the purity of the target material is different in different application fields. The impurities U, Th, and other radioactive elements have a negative impact on MOS, while K, Na and other alkali metals have a negative impact on MOS interface performance. In addition, transition metals such as Fe, Ni, Cr and refractory metals such as W, Mo, and Nb generate leakage current at the interface. Therefore, the content of the above impurity elements should be strictly controlled.

  • Porosity

The target material should be dense enough. If there are pores in the target material, the gas in the pores will be released in the sputtering process, and an arc will be generated, causing tiny particles to sputter out of the target and generating uneven points on the film.

  • Grain size

The size of grain affects sputtering uniformity and sputtering speed. Typically, the grain size is required to be less than 100 microns, since the large grain size causes uneven sputtering and irregular nodules on the target. Meanwhile, no crystal band is allowed and the grains should be uniform on the whole target surface.

  • Texture

The texture difference has a great influence on sputtering speed, and (100) texture is usually required.

  • Surface finishingment

If the surface finish of the target material is not high enough, it is easy to form small bumps in the sputtering process.

  • Uniformity

Uniformity should be consistent in all directions of the target and between each target.

Tantalum-target
Tantalum-target

Applications of the tantalum target

In recent years, with the rapid development of semiconductor technology, electronic devices are becoming more and more miniaturized and integrated, and the thin film technology is used in the manufacturing process.

Tantalum target is mainly used for sputtering coating. Tantalum film, tantalum alloy film, silicon tantalum oxide film, tantalum nitride film, and tantalum oxide film have a wide range of applications. Tantalum oxide is used in the resistance and capacitance of integrated circuits and the resistance of hybrid circuits; tantalum film forms a barrier layer to prevent corrosion when spraying printed circuit; tantalum film is also used as seed in magnetic resonance devices. The total global demand in these areas is about 30t annually.

Another major use of tantalum is as a diffusion barrier between silicon and copper conductors in integrated circuits. Compared with other metals, tantalum, as a barrier layer of copper, has a lower diffusion rate, higher interlayer bonding strength, and heat resistance. The global demand for sputtering targets in this application field is expected to increase to 200t.

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Applications of Tantalum in the Electronic Industry

Tantalum and its alloy have a high melting point, corrosion resistance, excellent high-temperature strength, and are free of radioactive, etc, are widely used in the electronics industry, chemical industry, aerospace, weapon system, the medical field, etc. Applications of tantalum materials in the electronic industry mainly include tantalum capacitors, integrated circuits, electron tubes, storage devices, and passive devices.

tantalum

Tantalum Capacitors

Tantalum capacitors have strong corrosion resistance and can maintain stable electrical and physical and chemical properties under various environmental conditions. In addition, it also has a high resistance rate (7.5 x 1012 Ω cm), a large dielectric constant (27.6), and a small leakage current.

Tantalum Capacitors
Tantalum Capacitors

Tantalum has the characteristics of a valve metal, and the dense oxide film generated on its surface has unidirectional conductivity, which is suitable for capacitors. Tantalum capacitors are large in capacity and small in volume. Their capacitance is three times that of aluminum capacitors, while their volume is much smaller than that of aluminum capacitors. The tantalum capacitor has a working temperature range of 80 ~ 200 ℃, so it can meet the demand of different temperatures. In addition, tantalum capacitors also have strong stability and heat resistance, which makes them highly reliable materials in the electronics industry, as well as widely used in military and high-tech fields that need to ensure high reliability.

Integrated circuit

Tantalum has been introduced into the semiconductor industry as a barrier layer film material to prevent the diffusion of copper atoms to silicon wafers. Copper does not form a compound with tantalum and nitrogen, so tantalum and tantalum base films are used as a barrier layer to prevent the diffusion of copper. In order to prevent copper atoms from diffusing into silicon matrix, tantalum nitride, tantalum silicide, tantalum carbide, tantalum nitride silicide, tantalum nitride carbide, and other tantalum base films are used as barrier layers with good effects.

Tantalum-based films have high conductivity, high thermal stability, and excellent corrosion resistance, which are highly resistant to foreign atoms.

Tantalum
Tantalum in Semiconductor Chips

Memory device

Tantalum oxide based resistance variable memory (RRAM) has the advantages of simple structure, fast reading and writing speed, strong miniaturization and compatibility with the CMOS process. Tantalum oxide material has good thermal stability that can reach 1100 ℃. There are only two stable phases between the tantalum and oxygen, namely Ta2O5 and TaO2, which also have two very high oxygen capacity ratio under the high temperature of 1000 ℃.

Passive device

When tantalum nitride film is exposed to air, an oxide layer will naturally form on the surface to protect the film from erosion in the presence of water vapor and voltage. Tantalum nitride chip resistors do not cause catastrophic failure of the device due to poor package or protective coating integrity.

At present, the application field of capacitor grade tantalum wire is further expanded with the rapid development of the electronic market. However, the development of tantalum capacitors has been greatly restricted due to various reasons, such as the increase in production cost, the further consumption of resources, and the intensified competition among ceramic capacitors.

Please visit http://www.samaterials.com for more information.

Why is Tantalum Widely Used in Electronic Industry?

Since the 1950s, TZM alloy (Mo-0.5 Ti-0.1 Zr-0.02 C) has been developed to meet the needs of the nuclear power system, aviation, and aerospace industry. It is the most widely used molybdenum alloy in the industry and the earliest refractory alloy used as a high-temperature structural material. However, the low-temperature brittleness of molybdenum alloy greatly limits its application.

tantalum metal

Tantalum metal has a lower plastic brittle transition temperature (196 ℃) and has better performance on the workability, weldability, ductility, and oxidation resistance at room temperature than that of molybdenum and tungsten in refractory metals. In addition, tantalum and its alloys with high melting point (2996 ℃), corrosion resistance, excellent high-temperature strength, and free of radioactive, etc, are widely used in the electronics industry, chemical industry, aerospace, weapon system, and the medical field, etc.

Tantalum metal
Tantalum metal

The applications of tantalum materials in the electronics industry mainly include tantalum capacitors, integrated circuits, electron tubes, memory devices, and passive devices.

Tantalum capacitor

Tantalum has the metal property of a valve, and the compact oxide film formed on its surface has unidirectional conductivity, which is suitable for making capacitors. Tantalum capacitors have a large capacity and small volume, and their capacitance is three times that of aluminum capacitors, but their volume is much smaller than that of aluminum capacitors. The working temperature of the tantalum capacitor ranges from -80 to 200 ℃, which can meet the demand of different temperatures. Besides, tantalum capacitors have strong stability and heat resistance performance and become a kind of material with high reliability in the electronics industry, which is widely used in military and high-tech fields that need to ensure high reliability.

Tantalum capacitor
Tantalum capacitor

Integrated circuit

Tantalum material is introduced into the semiconductor industry as a barrier layer thin-film material used to prevent the diffusion of copper atoms to silicon wafers. There are no compounds are formed between copper and tantalum, and copper and nitride, so tantalum and tantalum base membranes are used as barrier layers to prevent copper diffusion, and the typical thickness of the barrier layer is 0.005 ~ 0.01μm. In order to prevent the diffusion of copper atoms into the silicon matrix, tantalum nitride, tantalum silicide, tantalum carbide, and silicon nitride are used as barrier layers.

Memory device

Tantalum oxide matrix resistive memory (RRAM) has the advantages of simple structure, fast read and write speed, strong instability, and compatibility with the CMOS process. The permittivity of tantalum oxide material is very high, which is about 25. Moreover, there are only two stable phases between ta-O, Ta2O5 and TaO2, which have high oxygen capacity ratio under the high temperature of 1000 ℃.

Passive device

When tantalum nitride film is exposed to air, the surface will naturally form a layer of the oxide layer to protect the film from erosion in the presence of water vapor and voltage. The chip resistance of tantalum nitride will not cause catastrophic failure of the device due to the poor integrity of the package or protective coating.

RRAM
RRAM

When researchers discovered tantalum’s high-temperature resistance, good ductility, and corrosion resistance, the research on tantalum metal began. At present, the application field of capacitor grade tantalum wire is further expanded with the rapid development of the electronic market. However, the development of tantalum capacitors is greatly restricted due to various reasons, such as the increase in production cost, the further consumption of resources, and the intensification of the competition between ceramic and other capacitors.

In recent years, the market consumption of capacitor tantalum wire has been maintained at about 160 tons per year. With the development and use of military capacitors and the miniaturization and chip type of capacitors, the capacitor-grade tantalum wire gradually develops toward the thick and thin poles.

Please visit http://www.samaterials.com for more information.