Why is Tantalum Widely Used in Electronic Industry?

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.

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Tantalum Processing Materials used in the Electronics Industry

Tantalum Processing Materials used in the Electronics Industry

With the advent of the era of big data, the storage of big data has become a matter of concern. Tantalum materials are developing at an amazing speed in today’s rapid development of the electronics industry.

tantalum target

Tantalum capacitors

Tantalum capacitors are one the indispensable electronic components for radar, aerospace aircraft, and missiles, and are widely used in civil applications, such as mobile communication, electronic equipment, instruments, and other aspects. On the contrary, the development of the electronic industry requires more and more stringent miniaturization and high reliability of tantalum capacitors.

Tantalum capacitors
Tantalum capacitors

Capacitor grade tantalum wire

Capacitor grade tantalum wire is used to make anode lead of tantalum electrolytic capacitor, and its advantages are high permittivity of the oxide film and high reliability. Compared with metallurgical tantalum wire, capacitor grade tantalum wire has high chemical purity, good surface finish, and anti-oxygen brittleness. Using tantalum powder as raw material, capacitor tantalum wire is made by powder metallurgy method after forming tantalum bar, and then through rolling, drawing, and other metal plastic processing. As a result, its surface is smooth and clean, and no grooves, burrs or other defects.

Capacitor grade tantalum wire
Capacitor grade tantalum wire

The important performance indexes of capacitor-grade tantalum wire include tensile strength, linearity, chemical composition, leakage current, etc. The diameter of the capacitor-grade tantalum is generally between Φ0.15 mm to Φ1.0 mm, and the tensile strength is between 400mpa and 1700mpa.

Tantalum target

The purity of the tantalum target is 99.95%, the surface is smooth, the grain diameter is less than 100μm, and the grain texture is mainly [111] type texture. Because of its high conductivity, high thermal stability, and barrier to foreign atoms, tantalum can be used as a barrier layer to prevent copper from diffusing into silicon. As electrode materials and surface engineering materials, tantalum target has been widely used in liquid crystal display (LCD) and heat-resistant, corrosion-resistant, and highly conductive coating industries.

Tantalum target
Tantalum target

Tantalum sputtering target material has become a key raw material in the semiconductor industry, which is irreplaceable and has a broad application prospect. The tantalum sputtering target is completed by physical vapor deposition. The specific process includes high-pressure accelerated gaseous ions bombarding the tantalum target surface, enabling the atoms on the target surface to get enough energy and break free, sputtering on the silicon chip, and finally forming the precise wiring structure in the semiconductor chip with photolithography, corrosion, and other processes. Tantalum material can be used for various thin-film applications, as diffusion barrier material applied to memory devices, such as gate electrodes of MOSFET devices and protective coating on printing head devices.

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What are the Medical Applications of Tantalum?

What are the Medical Applications of Tantalum?

Metal materials have excellent comprehensive mechanical properties and anti-fatigue properties and are especially suitable for bone replacement implantation of human-bearing parts. Therefore, many kinds of metal materials such as stainless steel, titanium alloy, and cobalt-base alloy have been widely used in the clinic as biomedical materials and have achieved a good therapeutic effect.

tantalum stents

However, the complex human body environment will lead to corrosion of materials and the release of toxic elements, which will lead to the reduced biocompatibility of metal materials. In addition, the elastic modulus of the metal material is too different from human bone tissue, and it is easy to produce a stress shielding effect, which is not conducive to the growth and remodeling of new bone and even leads to secondary fracture.

At present, tantalum metal attracts the attention of medical workers and materials researchers with its unique advantages and is widely used in the following aspects.

biomedical materials
Biomedical materials

Tantalum wire

Tantalum is so malleable that it can be made into even finer strands of hair. As a surgical suture, tantalum wire has the advantages of simple sterilization, less stimulation, and high tensile strength, but it also has the disadvantages of not easy knotting. Tantalum wire can be used to suture bone, tendon, and fascia, as well as reduce suture or internal dental fixation. It can also be used as a suture line for internal surgery or embedded in artificial eyeballs. Moreover, tantalum wire can even replace tendons and nerve fibers.

Tantalum sheet

Tantalum metal can be made into tantalum sheets of various shapes and sizes and implanted according to the needs of various parts of the human body, such as repairing and sealing the cracks and defects of broken skull bones and limbs fractures. An artificial ear made from tantalum sheets is attached to the head before the skin is transplanted. After a while, the new skin grew so well that it was barely visible as an artificial tantalum ear.

Tantalum stents

Tantalum wire can be used to weave the reticulocytes stent. Tantalum stent can be clearly seen under X-ray, which is very convenient for monitoring and follow-up, and there is no fracture and corrosion in the body for a long time. Tantalum has good flexibility, so the stents can better adapt to the normal pulse of arteries and can be released quickly and accurately.

Tantalum stents

Porous tantalum rod

Porous tantalum rod is a kind of honeycomb three-dimensional rod-shaped structure with characteristics of the human cancellous bone structure, with an average porosity of 430~m and a porosity of 75 ~ 80. The elastic modulus of the porous tantalum rod is about 3GPa, which is between the cancellous bone (about 1GPa) and cortical bone (about 15GPa), far lower than the commonly used titanium alloy implanted human material (about 11OGPa), thus avoiding the stress shielding effect.

Porous tantalum rod implantation is mainly used for the treatment of avascular necrosis of the femoral head in the early and middle stages. Femoral head necrosis is a kind of functional disease caused by the destruction of the blood circulation of the femoral head. It may affect the function at any age, but it usually occurs in young people. For the treatment of early femoral head necrosis, the main methods include reducing the internal pressure of the femoral head, increasing the blood supply of the femoral head, and preventing or slowing the deformation of the femoral head. The porous tantalum rod has a good supporting effect on the necrotic area of the femoral head, avoids the collapse of the femoral head, and has the potential for revascularization in the necrotic area of the femoral head.

Porous tantalum artificial joint

As an artificial joint material, the porous tantalum also has obvious advantages. The porous tantalum has a certain elasticity. When it interacts with the cortical bone with a relatively large elastic modulus, it will produce slight deformation in a certain range without fracture. This property allows the porous tantalum acetabular cover to better match the bone acetabular, improving the initial stability of the implant and reducing the possibility of acetabular fractures.

The results of the clinical experiment of total knee replacement with porous tantalum showed that the structure of porous tantalum provided sufficient support, and the patient’s bone healed well. In addition, the reduction of bone mineral salt density in patients using tantalum total knee replacement is smaller than that in patients using the cobalt-chromium alloy, but the long-term clinical effect remains to be further studied. Due to the inertia of tantalum itself and the appropriate mechanical properties and good biocompatibility of porous tantalum with the human body, porous tantalum will play a greater role in the field of artificial joints.

Porous tantalum artificial joint
Porous tantalum artificial joint

Porous tantalum filler material

Porous tantalum can also be used as filling material for all parts of the human body, such as tissue reconstruction after tumor resection, dissolving filling of the neck and lumbar spine, and vertebral arch replacement. Because of the nearly perfect fusion of porous tantalum in mechanical properties, tissue growth, and processing properties, it provides a wide design space for the molding of porous tantalum.

Tantalum coating

Tantalum metal has been used for its excellent corrosion resistance, and it is coated on the surface of some medical metal materials to prevent the release of toxic elements and improve the biocompatibility of the metal materials, as well as the visibility of materials in the human body. In addition to metallic materials, tantalum can be coated on non-metallic materials such as carbon cage surface tantalum for spinal fusion, the tantalum coating increases the strength and toughness of the carbon cage to fit the spine and better meet the requirements of the surgical process. Tantalum can also be coated on the surface of materials with some polymer composites to improve the visibility and biocompatibility of materials.

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How do tantalum products work in modern industry?

How do tantalum products work in modern industry?

Capacitor tantalum powder

Tantalum electrolytic capacitor is an electronic device that takes tantalum as a metal anode and generates dielectric oxide film on the tantalum surface by anodic oxidation. The most important difference between tantalum capacitors and other types of capacitors is the quality of the tantalum oxide dielectric film, which has a high dielectric constant and breakdown voltage.

Generally speaking, the higher the purity of tantalum powder, the higher the breakdown voltage of the tantalum capacitor anode film. The tantalum powder has a high specific surface area, which can be remained even after compaction and sintering due to its special pore structure.

tantalum powder

Apart from the tantalum powder, tantalum foil is also used in foil capacitors, and tantalum wire is used as capacitor anode lead. In 2000, the annual output of tantalum capacitors reached 25 billion tons, requiring 800 tons of tantalum powder and nearly 150 tons of tantalum wire. Excellent performance such as high reliability and compactness, high efficiency, and long shelving time make tantalum capacitors be used in the instrument and control system of computers, communication systems, aircraft, missiles, ships, and weapon systems.

Tantalum and its alloys

The alloying of tantalum or tantalum-based alloy is usually carried out in the electron beam furnace. In order to obtain the ingot with uniform composition, vacuum arc remelting (VAR) is required after the smelting and purification in the electron beam furnace. All tantalum and tantalum alloy products are processed by electronic beam casting, and the use of vacuum arc remelting depends on the use of the product.

Tantalum alloy has the lowest ductile-brittle transition temperature, good low-temperature ductility, small work hardening coefficient, and excellent high-temperature strength, which is an ideal structural material for working under 1600-1800 ℃. At present, Ta-W and Ta-Nb alloy materials are mainly used in the manufacture of aerospace industry and space nuclear power system components.

Tantalum alloys

Other applications of tantalum

At present, the global annual consumption of tantalum is about 900 tons. The electronics industry is the largest and most promising application of tantalum, accounting for an estimated 66% of total consumption; the second application of tantalum is in the cutting tool industry, which accounts for 22 percent of total consumption; tantalum, as a superalloy high temperature strengthening additive, accounts for 6% of the total consumption; tantalum and tantalum alloy account for 3% of total consumption in valves, heat exchangers and plug-in heaters of chemical industries. As a biological material, tantalum is highly compatible with body fluids. In thoracic surgery, tantalum U nail is used to close vessels and arteries without an allergic reaction, and medical fields such as holes used to seal the skull during craniotomy account for about 1% of tantalum use. The other 2% of tantalum is used for military purposes.

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.

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