Single Layer PCB vs. Double Layer PCB
In generally, FR4 PCB, Aluminum PCB, Copper PCB and Ceramic PCB all can be made into single layer PCB or double layer PCB.
Single Layer PCB
Single layer PCB is the most commonly used because it is easy to design and practice. This PCB covered a conducting material on the one side of the board. Single layer PCB with a good heat dissipation, each chip dissipates heat on one PCB, the LED headlight can be in a high lumen. But the width of two chip of two single layer PCB is too wide that is over 3mm. Limited by the width, it can not simulate the halogen bulb tungsten wire, the light beam is not clear with a dark area.
Double Layer PCB
This PCB covered two conducting material on both sides of the board. It provides a closer distance between the two sides of the chips, which is similar to the thickness of halogen bulb tungsten wire. For this result, it imitates the halogen bulb light-emitting forms, the light beam is better. However, both side of chips dissipate heat on one PCB, the heat cannot be too high, so it limits the lumen for LED headlight.
It does not rely on the area of PCB about the PCB heat dissipation problem. Thermal Management technology is another core part of PCB application.