Through-hole technology (also spelled "thru-hole"), refers to the mounting scheme used for electronic components that involve the use of leads on the components that are inserted into holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side either by the manual assembly (hand placement) or by the use of automated insertion mount machines.

The quality of the solder joint is important for several reasons. The solder joint is the actual connection between the component and the board. The quality of the solder joint is equivalent to the quality of the connection. The "look" of the solder joint is less important but is usually indicative of the quality of the solder joint.

Benefits of Through hole Assembly :

• It is used for high reliability products that require stronger connections between layers i.e it is commonly used in military and aerospace products.
• It is used for heavier components such as electrolytic capacitors or semi-conductors in large packages such as TO-220.
• For components like plug connectors or electromechanical relays that require great strength in support.