| Read Access Memory (RAM): Memory that offers access to storage locations within it by means of X and Y coordinates. |
| Read Only Memory (ROM): Random access storage that is unchangeable after manufacture. |
| Reflow Oven: An oven used to heat SMT boards to harden the solder paste and form strong, reliable joints between components and the board surface. |
| Reflow Soldering: Applying heat to a PCB with the purpose of melting existing solder paste and rejoining metal layers. |
| Registration: Location of a circuit with reference to fixed points. |
| Resist: Material used to mask or to protect certain areas of a pattern from etching, solder, or plating. |
| Resistance: A measure of the difficulty of moving an electrical current through a material when voltage is applied. |
| Rework: Repeating on or more manufacturing operations to bring a non-conforming item into conformance. |
| Robber: An area designed around a printed circuit board to absorb unevenly distributed current. |
| Route (or Track): The layout or wiring of an electrical connection. |
