Multilayer
For highly complex electronic assemblies, the upper and lower surfaces areas of the pc board often are not sufficient for all the tracks required to connect the components. To overcome this shortage, additional wiring layers are integrated into the pcb. These multilayer pcb’s may have up to 24….32 layers. These layers absorb large amounts of heat, and the soldering system has to be able to supply the necessary amount of heat, if it is to form acceptable top-side fillets.