Through-hole mounting uses leads that are inserted into holes drilled on PCBs and are then soldered to pads on the other side of the board by automated insertion machines or by hand placement. The resistors used are plated through-hole (PTH) with long, pliable leads that are either hand-soldered onto a board or inserted into a breadboard. The leads, once placed, are then trimmed. These resistors are made from carbon, metal, or metal-oxide film. Through-hole technology are fit for high-power or high-voltage applications. These resistors feature low cost, high performance and a wide range of resistance values. Some typical examples of them are Microhm Electronics' EE series, NUB series and HPMRY series.
Wirewound resistors have a metal wire wound around a ceramic, plastic, or fiberglass core. The wire ends are soldered or welded to caps at the ends of the core and the resistor assembly is covered with a layer of enamel or paint for protection. The most typical one is the metal clad wirewound resistor, and NUAL series is the model for Microhm Electronics.
Through-hole mounting provides strong mechanical bonds, but the drilling required makes the boards more expensive to produce. When using multi-layered boards, they also limit the available routing area for signal traces below the top layer since the holes need to go through all layers. As a result, through-hole mounting is usually reserved for bulkier or heavier components or those that require great strength in support such as plug connectors.
