In addition to wired LEDs, SMD LEDs (Surface Mounted Device LEDs) can also be used. Being fixed directly on the solder pad of the printed circuit board they provide significantly better heat dissipation and the LEDs can be assembled more densely on the board. Thus a higher light intensity and homogeneity can be achieved. Another development is the chip-on-board technology (COB) where different light emitting chips (dyes) are densely bonded on the LED pad, so that the fill factor of the LED (ratio between luminous area and total area) is increased. These modules reach the highest light intensity, but such multi- chip LEDs also require more effort to dissipate the heat.