How to Select a Tantalum Capacitor?

What is a tantalum capacitor?

At present, the tantalum capacitor is still a kind of charge energy storage device with small volume but high capacity, and the amount of electric energy it can store depends on the thickness and area of the medium. The dielectric capacity of tantalum capacitor’s dielectric layer can reach 120KV/mm, and its relative dielectric constant is 27 times 10-12 farad/meter. Therefore, tantalum capacitors can withstand extremely high field strength in a very thin medium layer, which is the root cause of its small size but high capacity. Tantalum capacitors are not only used in military communications, aerospace and other fields, but also in industrial control, video equipment, communication instruments, electric vehicles, and other products.

Tantalum capacitors are mainly used for filtering, energy storage, and conversion, marking bypass, coupling, and decoupling and acting as the time constant elements. Pay attention to its performance characteristics in the application, and the correct use will help to give full play to its functions.

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How to select appropriate tantalum capacitors?

To choose tantalum capacitors, the first problem is to choose encapsulation, voltage resistance, and capacitance. The capacity determines the size (encapsulation) of tantalum capacitors; on the contrary, what size determines what capacity and pressure tolerance can be achieved. According to the market, the most common problem is that engineers ignore this problem in the design process, and always want to achieve the desired parameters on the smallest device.

For example, the capacity of type A 10UF can be seen to have a withstand voltage of 4v6.3v10v20v, however, if you want to use 25V10UF, only the B type of tantalum capacitor can be used. In addition, since tantalum capacitors are used for derating, generally 70% of the capacitors need to be used, that is, the working voltage is 10V, which should be divided by 0.7. The capacitors can only be used with 16V withstand voltage.

How to purchase the original tantalum capacitors?

Due to the wide variety of electronic components and special uses, the current component market is full of fake products, dismantling and refurbishing products. The choice of a high-quality, long-term cooperation of the business is particularly important.

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Currently, the world mainly has the following five brands of tantalum capacitors: AVX, KEMET, VISHAY, NEC, and NICHICON. Tantalum capacitors on the market are divided into two types: yellow tantalum and black tantalum. In simple terms, the black tantalum is produced by molding tantalum powder into shape, while the yellow tantalum is formed on the surface with polyoxide resin. Due to the production process, the internal space of black tantalum is not utilized most effectively, so the capacity of yellow tantalum is larger than that of black tantalum.

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Why Can the Tantalum Metal be used in Medical Operations?

Since the discovery of tantalum in 1802, the understanding and development of tantalum have a long history. Tantalum metal is characterized by corrosion resistance, hard quality, high melting point, good thermal conductivity, good affinity with the human body and easy processing, which is widely used in the fields of metallurgy, chemical industry, atomic energy, aerospace, electronics, and medical devices.

Biocompatibility test of tantalum metal

Biocompatibility refers to the concept of various biological, physical and chemical reactions resulting from interactions between materials and organisms. Generally speaking, it is the degree of compatibility between the material and human body after implantation, that is, whether it will cause the toxic effect on human tissue.

The principle of biosafety is to eliminate the destructive effect of biological materials on human organs, such as cytotoxicity and carcinogenicity. If biomaterials are to be successful, they must at least be accepted by the host without harmful effects. Therefore, biological safety evaluation, that is, biological evaluation, should be carried out on biological materials.

porous tantalum

Insoluble tantalum salt is not absorbed by the human body through oral or local injection, and the absorption amount of soluble tantalum salt in the gastrointestinal tract is very small. Once tantalum enters the body, the main carrier responsible for the removal of tantalum is phagocytes. In the body, phagocytes can survive and have no cellular degeneration after 1h exposure to tantalum dust, with only a significant increase in glucose oxidation. Under the same conditions, silica dust can cause severe cytoplasmic degeneration and death of phagocytes, indicating that tantalum is non-cytotoxic.

Through abundant domestic and foreign materials, it is found that porous tantalum has the following advantages compared with titanium alloy.

The advantages of porous tantalum nails are one with the advantages of metal materials. After implantation, as the bone tissue grows, the fixation strength of porous tantalum nail will gradually increase. Meanwhile, as the bone tissue grows, blood circulation is also introduced into the nail body, which is conducive to preventing the occurrence of fracture nonunion and femoral head necrosis. The porous tantalum nail has excellent biocompatibility with bone. It does not need to be taken out after implantation, which can effectively prevent the risk of fracture after the removal of internal fixation. Therefore, porous tantalum nail has a good long-term effect in the treatment of femoral neck fracture and has a broad application prospect in other disciplines of orthopedics and medicine.

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Application case of tantalum nail

Porous tantalum nail implantation is an ideal minimally invasive surgical treatment for the treatment of early Avascular Necrosis of Femur Head (ANFH) in adults. It has unique physical and biological advantages and is expected to achieve therapeutic effects that traditional therapies do not, as well as in line with the current concept of minimally invasive. For osteonecrosis in stage Ⅰ and Ⅱ young patients, it can relieve pain and minimize complications, at least slow down or even avoid the joint replacement, but the long-term curative effect is yet to be large sample especially central level and long-term follow-up.

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.

Where Can We Find Tantalum Metal?

Tantalum metal mainly exists in tantalite ore and is symbiotic with niobium. Tantalum is of moderate hardness and ductility and can be drawn into tantalum wire or tantalum foil. Tantalum has a wide range of applications due to its characteristics, and it widely exists in tantalite, tantalum alloy, tantalum powder, tantalum capacitors, etc.

Tantalum alloy is an alloy based on tantalum adding other elements. The tantalum anode oxide film is stable and corrosion resistant. It has excellent dielectric properties and is suitable for making the electrolytic capacitor. Tantalum is highly resistant to chemical corrosion. Except for hydrogen fluoride, sulfur trioxide, hydrofluoric acid, hot concentrated sulfuric acid and alkali, tantalum can resist the corrosion of all organic and inorganic acids. Therefore, it can be used as corrosion resistant materials for chemical industry and medicine.

Tantalum alloy

As tantalum is similar to some rare elements such as uranium, thorium, rare earth, titanium, zirconium, tungsten, and common elements tin, calcium, iron, and manganese in crystalline chemistry, it is easy to have equivalence and heteromorphism.

The compact oxide film formed on the surface of metallic tantalum has the properties of valve metal of unidirectional conduction. The anodic film made of tantalum powder has chemical stability (especially in acidic electrolyte stability), high resistivity (7.5 x 1010 Ω, cm), dielectric constant (27.6) and small leakage current. Tantalum is not only the raw material for the production of pure metal tantalum but also used in the electronics industry. Lithium tantalate monocrystals and special optical glass with high refraction and low dispersion can be used as a catalyst in the chemical industry.

Tantalum oxide is a white powder insoluble in water and acids, but soluble in molten potassium bisulfate and hydrofluoric acid. The minerals containing tantalum and niobium are mainly iron tantalum and calcined greenstone. The ones containing more tantalum are called tantalite, while the ones containing more niobium are called niobite.

tantalum capacitor

The design of tantalum capacitors requires that the product performance parameters of tantalum capacitors can meet the circuit signal characteristics. However, it is often impossible to guarantee that the above two tasks are done well. Therefore, it is inevitable that failures of one kind or another will occur in the process of use. The solid tantalum capacitors were first developed in 1956 by Bell Laboratories in the United States. Tantalum capacitors can easily obtain large capacity, and there are few competitors in power filter, ac bypass, and other applications.

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