CIRCUIT DESIGN
• Input devices (sensors, switches)
• Output devices (relay contacts, LEDs, RS-232 line)
• Power source(s) available
• Block diagram of system
• Functions to be preformed
• Operating range of device
• Cost target
• Processor or analog control

SCHEMATIC
• Bill of Material
• Specification Sheets

PCB LAYOUT
• Density of circuit board
• Thru hole, surface mount components, or both
• Single or double sided component placement
• Special routing requirements (high voltage, current)
• Specific component placements (switches, sinks, lights)
• Number of circuit layers
• Silkscreen, soldermask layers required
• Thickness of board material
• Rigid or flex board required
• Overall board size and dimensions
• Slots, cutouts, or tabs in board outline
• Mounting hole sizes and locations
• Panelized or multiple board layout
• Unique components used (ICs, sensors, heatsinks)

BARE CIRCUIT BOARDS
• Number of boards required
• Delivery time
• Electrical testing required

POPULATED CIRCUIT BOARDS
• Are components supplied or purchased
• Overage on parts
• Spare boards, (bare or stuffed)
• Is testing of boards required

SYSTEM DESIGN
• Case size and ergonomic considerations
• Material, (metal case, molded plastic, open frame)
• Environmental requirements (ambient temp, waterproof)
• Safety issues (interlocks, hot surfaces, voltage)
• Power requirements
• Customer interface (switches, lights, communications)
• Agency approvals (UL, CE)