Why is serpentining used? This process is used in order to meet the target lengths for traces that are determined during the simulation process. This is also used in order to make sure that when the signals travel down the traces, they will meet up at the device in unison. Each signal takes a finite amount of time to travel between the source and destination, called the propagation delay, and therefore, varying trace lengths are needed if one signal needs to arrive at the destination at the same time as another.