Through-hole technology inserts component leads into plated holes and solders them by wave, selective soldering or hand. It gives strong mechanical joints, which is why connectors, transformers, big capacitors and parts that take physical stress use it. It costs more board area and assembly time than surface mount, and its holes block routing on every layer they pass through.
Keep the power connector through-hole, it gets yanked on and SMT pads would peel right off.
Also heard as
- THT
- through-hole technology
- TH
Do not mix it up with
- PTH: A PTH is the plated hole itself; through-hole is the mounting technology that puts leads in it.
Related terms
PTH
Plated through-hole: a drilled hole whose walls are copper-plated to connect every layer it passes through.
Wave soldering
Soldering through-hole parts by passing the board over a standing wave of molten solder.
SMT
Surface mount technology: soldering components onto pads on the board surface instead of through holes.
Thermal relief
Spoked connection between a pad and a copper plane that limits heat flow so the joint can be soldered.