UV LED is a kind of LED, which is single-wavelength invisible light, generally below 400 nm. There are mainly 365 and 395 nm. UV curing usually uses 365 nm wavelength. Through special design, the UV LED can emit a complete continuous ultraviolet band to meet the production needs in the fields of edge sealing, printing and so on. Linear light source has long life, cold light source, no heat radiation, life is not affected by the number of times of opening and closing, high energy, uniform irradiation to improve production efficiency, no toxic substances than traditional light source is safer and more environmentally friendly.
Ultraviolet LED (UVLED) consists of one or more InGaN quantum wells sandwiched in a thin GaN sandwich structure. The active region formed is the cladding layer. By changing the relative ratio of InN-GaN in InGaN quantum wells, the emission wavelength can be changed from violet light to other light. AlGaN can be used to fabricate cladding and quantum well layers in UV LED by changing the proportion of AlN, but these devices have poor efficiency and maturity. If the active quantum well layer is GaN, as opposed to InGaN or AlGaN alloy, the emission spectrum of the device ranges from 350 to 370 nm.
Ultraviolet radiation is produced when the short electron pulse at the pump of the blue InGaN light emitting diode is applied. Nitrides containing aluminium, especially AlGaN and AlGaInN, can be used to fabricate shorter wavelength devices to obtain a series of UV LEDs. Diodes with wavelength up to 247 nm have been commercialized, LED based on aluminum nitride and capable of emitting 210 nm ultraviolet radiation has been successfully developed, and UV LED in 250-270 nm band is also being vigorously developed.
Semiconductors based on III-V metal nitrides are very suitable for making ultraviolet radiation sources. Taking AlGaInN as an example, at room temperature, the energy radiated by electrons and holes during recombination ranges from 1.89 eV to 6.2 eV with the change of the proportion of each component. If the active layer of LED is composed of GaN or AlGaN, its ultraviolet radiation efficiency is very low, because the recombination between electrons and holes is non-radiative. If a small amount of metal In is doped in the layer, the local energy level of the active layer will change, and then the electron and hole will radiate recombination. Therefore, when indium is doped in the active layer, the radiation efficiency at 380 nm is about 19 times higher than that without doping.
1. Cold light source, no thermal radiation, suitable for bonding of thermal sensitive materials
2. Open and close immediately, without preheating, the irradiation intensity can reach 500 mw/cm_-12 000 mw/c_or more.
3. The compact shape makes it easy to integrate the equipment into the fully automatic production line and equipment.
4. UV LED has no infrared radiation and harmful gases, which meets the ROHS standard. Compared with traditional mercury lamps, they are safer and more environmentally friendly.
5. Life of more than 20,000 hours, can significantly reduce operating costs and maintenance hours
6. The connection line is bending-resistant cable, which can be installed in movable part at will to meet the needs of repeated movement.
Cold light source, non-thermal radiation, low surface temperature rise of illuminated objects, solve the long-standing thermal damage problems in optical communication, liquid crystal production, especially suitable for liquid crystal edge sealing, thin film printing and other occasions requiring low temperature rise. Small calorific value can solve the problems of high calorific value of mercury lamp spraying equipment and unbearable worker. Moreover, the LED-UV light source emits high-purity single-band ultraviolet light with almost no infrared output. It belongs to the cold light source, and the workpiece will not be deformed by heating.
Efficiency: The light energy of LED-UV is highly concentrated in a certain UV spectral band with effective curing effect. The actual application effect and the curing effect of the traditional high-pressure mercury lamp UV light source with light intensity of 1000-2000mW/cm2 are comparable, thus shortening the curing time. Traditional mercury lamps have high brightness but high calorific value because of their wide spectrum. Ultraviolet spectra, which are really effective curing, only account for a part of the energy. A considerable part of the energy is in the visible (stray) and infrared (resulting in heat generation). The damage to the operator's eyes is serious and tolerant. It is easy to cause thermal deformation of workpiece.
(1) Extra-long life: The service life of LED-UV lamp is more than 10 times that of traditional mercury lamp, and the service life is not affected by the number of switches.
(2) Instantaneous switch can achieve maximum power ultraviolet output without preheating, and can be restarted instantaneously after closing.
(3) High energy, stable light output, good uniform effect of irradiation, improve production efficiency.
(4) The effective irradiation area can be customized from 20 mm to 1000 mm in length.
(5) Without mercury or ozone, it is a safer and more environmentally friendly alternative to traditional light source technology.
(6) Low energy consumption, power consumption is only 10% of the traditional mercury lamp curing machine, can save 90% of the electricity.
(7) Maintenance cost is almost zero, using UV-LED curing equipment saves at least 10,000 yuan per unit of consumables per year.
(8) Because the ultraviolet irradiation device and the related supporting devices are very compact, there is no need for the larger mechanical installation space and pipeline construction in the past, and the installation is simple and easy. It can be said that LED-UV curing system has further enhanced the environmental coordination of traditional UV curing system. LED-UV technology is an upgrade of the original UV technology.
Different application areas need different sizes of UV-LED light source, which can be generally divided into UV-LED point source, UV-LED line source and UV-LED surface light source. In terms of light intensity, the three are decreasing in turn.
1. UV LED spot light source: divided into UV LED fan point light source and UV LED pen point light source, spot diameter can be divided into 3 mm, 4 mm, 6 mm, 8 mm and 12 mm.
2. UV LED Linear Light Source: The shape of the light source is linear, and the length of the line can be customized.
3. UV LED surface light source: the light source is flat, the area of light source can be customized, and it is widely used.
According to industry: electronic field, such as optical, mobile phone, touch screen, hard disk, encoder and other components of the bonding, etc.
Printing field, such as printing of electronic components, flat printing and other arts and crafts fields, such as crystal, glass and other transparent products bonding, etc.
Medical field, needle bonding, etc.
Usage: UV glue, UV ink, UV resin hardening, etc.