Through holes are an essential component of printed circuit boards and play a crucial role in the design, manufacturing, and assembly processes. These holes are divided into PTH and N-PTH, this article TechSparks will discuss the basic concept of PTH and its role!
What is PTH in PCB and Its Purpose?
The full form of a PTH is a plated through hole, designed to accommodate through-hole components. As we all know, the PCB board does not function as a supply, but as a carrier for components, which means that we need to insert the pins of the components into the holes. However, after the drilling process, the inner walls of these holes consist of a non-conductive insulating material. This means that even if the pins are inserted, no electrical connection can be established.
Plated through-holes solve this problem by depositing a continuous layer of metallic copper on the inside wall of the hole. The copper layer adheres to the hole walls and extends throughout the entire depth of the hole. When the pins of the through-hole components or connecting wires are inserted into the plated through-holes, the metallic copper layer ensures a secure electrical connection, enabling the normal transmission of signals and currents.
How to Make Plated Through Hole PCB Boards
The process of creating plated through-holes begins with drilling, where holes are punched into the circuit board using a drill press or laser drilling machine based on the specifications in the design drawing. This drilling process generates waste and residues, which need to be cleaned to ensure the integrity of the holes.
To enhance the conductivity of the through-holes, a thin conductive layer can be applied to the walls before electroplating. This conductive layer serves as a base for the subsequent plating process. Now start electroplating, where the circuit board is immersed in an electrolyte solution containing metal ions. Under the influence of an electric current, the metal ions are deposited onto the conductive layer within the holes. If a specific copper thickness is required, the electroplating process may be repeated multiple times.
Once the plating process is complete, the plated through-holes undergo a cleaning and polishing step. This step is crucial to remove any impurities or excess plating material, ensuring the quality and flatness of the through-holes.