"The Sun circuit" offers wide variety of PCBs likes Single Sided PCB, Double Sided PCB, Metal Core PCB and Aluminum PCB including specialized high precision, high density and high reliability.
These types of boards have a conductor pattern on both sides of the board. Having two separate Conductor patterns require some kind of electrical connection between them. Such electrical 'bridges' are called 'vias'. A via is simply a hole in the PCB that is filled or plated with metal and touches the conductor pattern on both sides. Since the surface available for the conductor pattern is twice as large compared to a single-side board, and that wires now can cross (by routing them on opposite sides of the board), double sided PCBs are much more suited for complex circuits than the Single-sided.