Novel exposure system using light-emitting diodes and an optical fiber array for printing code marks

The feasibility of a novel economical and environmentally friendly exposure system using a light-emitting diode (LED) array as a light source was demonstrated. Such an exposure system is especially useful for printing two-dimensional code marks for the production management of semiconductor devices and liquid crystal display panels. The new system also uses an optical fiber matrix array connected to the LED array. The tips of the plastic optical fibers of 1mm diameter are heated and deformed into a square shape, and the square fiber ends are projected by a 1/10 reduction lens. Using LEDs with a central wavelength of 405 nm and an output power of 40mW/cm², quasi-square code mark patterns are printed with good size repeatability in a practically feasible short time of less than 2 s.