Capacitors Blog

Tantalum (atomic number 73) is a dense and ductile metal that is silver-gray in color. It is considered both a refractory metal, due to its high melting point of 5,425 degrees Fahrenheit (2,996 degrees Celsius), and a valve metal, due to its tendency to oxidize, which forms an insulating film. For these reasons, tantalum is commonly used in capacitors, or devices that store electrical charges. Cell phones, computers, mp3 players and many other electronic devices use tantalum capacitors, which have several advantages over other types of capacitors.

Tantalum Capacitors can pack a lot of energy into a very compact package. This is an essential quality when it comes to electronic devices, particularly cell phones, mp3 players and portable computers, which have been persistently getting smaller and smaller. Due to their high energy densities, engineers and designers can easily mount tantalum capacitors into the tiniest of circuits, without having to sacrifice energy output. According to engineersedge.com, a tantalum capacitor rated at 10-microfarads (which are units of capacitance, or the ability of a device to store a charge) can produce the same amount of voltage as a 100-microfarad aluminum capacitor.

This variant of the tantalum capacitor family is also known as the solid tantalum, and it is the variety that is most commonly used. Many millions of them are sued each day, and they can be found in many items of consumer and commercial electronic equipment.

The capacitor was developed by the Bell Telephone Laboratories by using a porous anode and then replacing the liquid electrolyte with a solid semiconductor. This overcome the problem od requiring a vent that is common to all other forms of electrolytic capacitor.

These capacitors are superior to electrolytic capacitors in many ways exhibiting excellent temperature and frequency characteristics. They are also smaller than their aluminium electrolytic counterparts.

The reliability of the solid tantalum capacitor is heavily influenced by environmental conditions such as temperature, humidity, shock, vibration, mechanical stresses, and electric stresses, including applied voltage, current, ripple current, transient current and voltage, and frequency. When using solid tantalum capacitors, therefore, provide enough margin so that the reliability of the capacitors is maintained.

Voltage and temperature are important parameters when estimating the reliability (field failure rate).

Tantalum SMD capacitors are widely used to provide levels of capacitance that are higher than those that can be achieved when using ceramic capacitors. The capacitor technology that is used within SMD tantalum capacitors is based on the solid tantalum capacitor technology. This is robust and enables very small capacitors to be made.
For many years tantalum capacitors were used in SMD applications because electrolytic capacitors were not able to survive the high temperatures of the soldering process. Now that electrolytic capacitor technology has been developed to withstand the soldering process, these capacitors are now also widely used. Despite this, the other advantages of tantalum capacitors are employed in many circuits, and they are still used in vast quantities.
For Suntan TS20 SMD Tantalum Capacitor, It has the following Features:

• Molded case available in six case codes
• Compatible with all popular 'High Volume' automatic pick and equipment
• Optical character recognition qualified

The advantages of Tantalum Capacitors can be summarised:
High reliability: Tantalum Capacitors are more reliable than many other forms of capacitor. Provided they are operated within their ratings they are able to provide an almost unlimited life. Their use is not time limited as in the case of electrolytic capacitors.

Wide operating temperature range: Tantalum Capacitors are able to operate over a very wide temperature range. They are often specified for operating over the range -55℃ to +125℃. This makes them an ideal choice for use in equipment for use in harsh environmental conditions.

Compatibility with modern production methods: Modern production techniques often expose components to high temperatures during soldering as the whole assembly is heated by infra-red heat. Using conventional leaded components only the board surface was heated and the amount of heat conducted by the leads was usually insufficient to damage the components. Tantalum capacitors are able to withstand the temperatures of SMT production and are there fore ideal for use in many new electronics designs.

Tantalum Capacitors offer many advantages over other types of capacitor. This has meant that their use has risen considerably over the years, and now they are widely used in all forms of electronics equipment. The advantages of Tantalum Capacitors can be summarised:

Volumetric efficiency: Tantalum Capacitors offer a very high level of volumetric efficiency - much greater than many other types. In particular they are better than electrolytic capacitors which are their main rival.

Good frequency characteristics: The frequency response of Tantalum Capacitors is superior to that of electrolytic capacitors. This means that they are more suitable for use in a number of applications where electrolytics could not be used.

This form of tantalum capacitor is also known as the wet tantalum capacitor and it was the first form to be introduced. It still offers the best space factor.A variety of electrolytes can be used within this form of tantalum capacitor. Those using sulphuric acid as the electrolyte have excellent electrical characteristics and the maximum working voltages that are manufactured tend to be a maximum of about 70 volts.

Basically this type of capacitor consists of a sintered porous anode of tantalum power. This is housed in a silver or silver plated container. The porous anode is made by pressing high purity tantalum power into a cylindrical body and then sintering in a vacuum at about 2000C.These wet tantalum capacitors are very much more expensive than their newer brothers and as a result they are not as widely used.

Tantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum powder, pressed into a pellet shape, as one "plate" of the capacitor, the oxide as the dielectric, and an electrolytic solution or conductive solid as the other "plate". Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume. Because of the size and weight advantages, tantalum capacitors are attractive for portable telephones, personal computers, and automotive electronics.

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Tantalum bead capacitors are polarised and have low voltage ratings like electrolytic capacitors. They are expensive but very small, so they are used where a large capacitance is needed in a small size.

Modern tantalum bead capacitors are printed with their capacitance, voltage and polarity in full. However older ones use a colour-code system which has two stripes (for the two digits) and a spot of colour for the number of zeros to give the value in µF. The standard colour code is used, but for the spot, grey is used to mean × 0.01 and white means × 0.1 so that values of less than 10µF can be shown. A third colour stripe near the leads shows the voltage (yellow 6.3V, black 10V, green 16V, blue 20V, grey 25V, white 30V, pink 35V). The positive (+) lead is to the right when the spot is facing you: 'when the spot is in sight, the positive is to the right'. 

• For example:   blue, grey, black spot   means 68µF
• For example:   blue, grey, white spot   means 6.8µF
• For example:   blue, grey, grey spot   means 0.68µF

Tantalum capacitor could cost more as raw material prices react to the closure of Australian mines.

"The suspension of tantalum production at the Wodgina mine means that the industry is entering uncertain times for tantalum," said Edmund Coady, sales director of component distributor Charcroft Electronics. "Capacitor manufacturers can renew their contracts with the tantalum powder manufacturers and accept a significant price increase in return for a reliable and continuous source of supply, or they can play a waiting game."