LED phenomena were noticed by man for the first time 90 years ago. This happened in Russia in 1923, when Oleg Losev in the radio engineering laboratory of Nizhny Novgorod first observed the glow of silicon carbide. Scientific articles on this topic were published in the 30s of the last century, and the first developments appeared only in the 70s. in Leningrad, Zelenograd and Kaluga. The active development of these techniques is associated with orders from the traffic police for the manufacture of 1000 traffic lights for the 850th anniversary of the capital, in which brighter green LEDs were used instead of incandescent lamps.
The LED is a semiconductor crystal attached to an aluminum or copper substrate and designed with an optical system and contact outputs. The SMD (surface montage details) LED differs from other types in that the parts in it are mounted directly on the surface. Crystal structures for this technology are grown by metal-organic epitaxy. During this process, within one day, it is possible to grow the required structures (chips) by a maximum of 12substrates.
Further, the obtained crystals are processed using high technologies: cases are mounted to them, exits are made, additional substances are applied, heat removal and the necessary focusing are organized. This stage is very expensive, so SMD LEDs are much more expensive than conventional lamps. It is believed that the cost of one lumen generated by an LED is 100 times higher than the same unit generated by a halogen lamp.
The positive characteristics of these systems include low heat, high color purity, the absence of infrared and ultraviolet radiation, sufficient strength, durability and safety. Today, Japan is the leading country for producing SMD LEDs.
When working with these elements, the following characteristics are usually considered:
- light that can be white (warm or cold), blue, green, yellow or red. SMD LEDs produce white light in many ways, including the RGB method, when different colors are mixed using a lens or other optical system;
- country of origin of the chip (usually Taiwan);
- luminous flux (in lumens);
- required voltage;
- number of crystals (chips);
- required current strength;
- glow angle (from 45 to 140 degrees);
- the presence or absence of a substrate, which is often paid extra.
SMD LEDs are widely used for lighting in a wide variety of fields. They are loved by designers for their high quality of light and electrical safety, and by utility workers for their low energy consumption and high vandal resistance. The only exception to the use of these technologies today is the availability of large areas, so they are not used in production. LED strips today can be seen in apartments, cafes and offices, including in rooms with a humid environment, because. there are certain types of diodes that are not afraid of water.
The service life of these devices is long enough (up to 50,000 hours for high-power samples), so we can say that SMD LEDs are the best way to illuminate in the future.
