How are Tantalum Capacitors used in Audio and Microphone Industry?

As tantalum capacitors have become more widely used in the market, their models and supply volumes have increased and prices have started to fall. Nowadays, aluminum electrolytic capacitors are replaced by tantalum capacitors in many industries. Of course, tantalum capacitors also have their own defects, such as not high enough pressure, which greatly limits its use area.

Tantalum is easily oxidized in the air. The tantalum capacitors made by using its oxide film as the medium have the function of repairing wound automatically, so they are durable and reliable. The tantalum oxide film is very thin, so the distance between two plates of tantalum capacitors is very close, and the reaction is very sensitive, so the charging and discharging speed is fast. These characteristics determine that tantalum capacitors are suitable for high-frequency, low-current and fast reactive circuits. Therefore, tantalum capacitors are widely used in satellites and other circuits requiring fast response and high reliability.

Tantalum capacitors are often used in advanced audio circuits, mainly high audio circuits, due to their high sensitivity and fast charge-discharge. As the loss of weak current to high audio is reduced, the relatively high pitch and sound quality are improved. In short, the tantalum capacitive microphone has the following advantages.

Capacitive Microphone
Capacitive Microphone

Broad frequency response

The vibrating membrane is the main component of the microphone which induces sound and converts it into the electrical signal, and the material and mechanism design of the vibrating film is an important factor to determine the sound quality of the microphone. The vibrating membrane of a capacitive microphone can be made of extremely thin material and the induced sound pressure is converted directly into an audio signal, so the bass of frequency response can extend to the ultra-low frequency below 10Hz, and the high tone can easily reach the ultrasonic waves of dozens of KHz, showing very broad frequency response characteristics.

Hypersensitivity

Because there is no load on the diaphragm, the diaphragm can be designed in such a light and thin way that the frequency response is superior and the sensitivity is excellent. It can sense extremely weak sound waves, output the clearest, delicate and accurate original sound.

Fast transient response

In addition to the characteristics that determine the frequency response and sensitivity of the microphone, the ability of the vibrating membrane to react quickly to sound waves, namely the “instantaneous response” characteristic, is one of the most important factors that affect the microphone’s timbre. The speed of the instantaneous response of the microphone depends on the weight of the whole vibrating membrane. The lighter the vibrating membrane, and the faster the reaction speed. The extremely thin vibrating film of capacitive voice head has the extremely fast transient response, so it can show clear, energetic and accurate timbre.

Capacitor microphone

Resistance to fall and impact

In general, the use of microphones can be caused by accidental fall and collision. Since the capacitive head is made up of lighter plastic parts and a sturdy light metal case, the impact force on falling ground is small and the failure rate of damage is low.

Small size and lightweight

The capacitive microphone has the advantages of small volume, light weight, high sensitivity and superior frequency response due to its ultra-thin vibrating membrane, so it can be designed into subminiature microphones (commonly known as small bees and small ants) and widely used.

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Tantalum Capacitors VS Ceramic Capacitors

The function of capacitors is to remove the crosstalk of various high-frequency signals generated by the chip itself to other chips so that each chip module can work normally without interference. In the high frequency electronic oscillating circuit, the SMT capacitance and crystal oscillator together form an oscillating circuit to provide the required clock frequency. Its main chemical components are nickel and chromium, and the shape is filamentous, so it is called nickel-chromium wire.

Ceramic capacitors

Ceramic capacitors are made by high dielectric constant capacitor ceramics, which are extruded into tubes, wafers or disks as the medium. It is divided into two types: high-frequency porcelain medium and low-frequency porcelain medium. Low-frequency ceramic dielectric vessels are limited to those occasions where they are used as by-passes or dc insulation in circuits with lower operating frequencies, or where stability and loss requirements are not high. Such capacitors are not suitable for use in pulse circuits because they are vulnerable to breakdown by impulse voltage.

Ceramic Capacitors

Tantalum Capacitors

Tantalum capacitors are characterized by long life, high-temperature resistance, high accuracy and excellent performance of the high-frequency filter. Tantalum capacitors can generally withstand high temperature and voltage and are often used for high-frequency filtering. Ceramic capacitors look a bit like patch resistors, but they are smaller in capacity and more expensive than aluminum capacitors and have relatively low voltage and current resistance.

Compared with ceramic capacitors, tantalum capacitors on SMT are labeled with capacitance and pressure resistance, and the surface color is usually yellow and black. SMT aluminum electrolytic capacitors have a larger capacity than SMT tantalum capacitors, which is more commonly seen on the display card, with a capacity between 300 VPS F and 1,500 VPS F.

Tantalum_capacitors
Tantalum Capacitors

The difference between tantalum capacitors and ceramic capacitors

They are made of different materials. As the name implies, tantalum capacitors use tantalum as the medium, while ceramic capacitors use ceramics as the medium. The capacitance of ceramic capacitors is much smaller than that of tantalum capacitors. Tantalum electrolytic capacitors can achieve a small capacitance, while the ceramic capacitor can hardly achieve the ideal performance when the capacitance is large.

Tantalum capacitors and ceramic capacitors also have different uses. Tantalum capacitors can be used as coupling, and the frequency range of such circuits as filter oscillatory bypass is large, while ceramic capacitors are mostly used in high-frequency circuits. Since tantalum capacitors are mainly made of tantalum, a very rare metal, so the capacitor grade tantalum powder is very expensive, while tantalum capacitors are sold at a high price and generally used only in high-end products that are not price-sensitive.

Multilayer ceramic capacitors are now the most widely used in almost all electronic products. In recent years, the capacity of ceramic capacitors has become larger and larger with the continuous progress of technology, and 47UF multi-layer ceramic capacitors have emerged. However, the large-capacity ceramic capacitors can only be made by a few big Japanese brands, so the price is still more expensive, which is similar to the price of tantalum capacitors.

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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 the good therapeutic effect. However, the complex human body environment will lead to corrosion of materials and 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 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 the 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, fascia, as well as reduction 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 limb 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 femoral head in the early and middle stage. 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 femoral head, increasing blood supply of femoral head, 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 of 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 the certain elasticity. When it interacts with the cortical bone with 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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