When sourcing a used SMT (Surface Mount Technology) machine, you must prioritize Placement Accuracy (e.g., ±0.03mm) and CPH (Chips Per Hour) to ensure it meets your production speed requirements. Verify the Component Range, ensuring the machine can handle everything from 01005 components to large ICs or BGA chips. Additionally, check the PCB size compatibility (Max/Min board dimensions) and the number of Feeder Slots available, as these directly impact your production flexibility and line capacity.