Curing resin with UV light is employed in various industries. Generally heat-curing is employed for polymerization but it can damage the subjects to be cured. On the other hand, using UV light at 200-400nm wavelengths can help to shorten the time to cure without the subjects damaged. As the light source for curing, mercury lamps are generally used but it difficult to control the temperature and the heat that mercury lamps generates. Short life mercury lamps cost for the replacement. On the contrary, longer life UV LEDs have no variation of light density and makes easier to control the temperature and the heat. Beside no mercury or any other harmful material is used, UV LEDs are good for environment. The compactness of UV LEDs are also good for curing in integrated circuits and any other applications which requires fine processing.