Surface-mount device refers to any individual part packaged with flat contacts or short leads that sit directly on top of the copper pads. Unlike older through-hole parts, SMDs do not require holes drilled through the board, allowing for much higher component density and automated assembly.
We need to swap out the through-hole resistors for 0402 SMDs to save board space.
Do not mix it up with
- SMT: SMD refers to the physical component itself, while SMT (surface-mount technology) is the manufacturing process used to assemble them.
Related terms
SMT
Surface mount technology: soldering components onto pads on the board surface instead of through holes.
Pad
Exposed copper area on a board where a component lead or terminal is soldered.
Pick-and-place
Automated machine that picks surface mount parts from reels and trays and sets them on a pasted board.
Through-hole
Mounting method where component leads pass through plated holes and are soldered on the far side.