Before delivery to the manufacturer, a Design Rule Check (DRC) must be performed to verify the PCB layout design; once the PCB is approved,
the deliverables can be released by the manufacturer.
Once the PCB has passed the final DRC check, a design file must be created for the manufacturer.The design file must contain all the information and data required to manufacture the PCB. It also includes notes and special requirements so that the manufacturer knows exactly what your needs are. The following are the files that need to be created:
1. Manufacturing files such as Gerber.
- TOP – Top copper layer (extension: board.gtl) Specifies the copper trace for the top layer of the PCB.
- SMT – Top layer of solder mask (extension: board.gts) The solder mask is used to prevent oxidation and the formation of solder bridges during the soldering process.
- SPT – top layer of solder paste (extension: board.gtp). Solder paste is used to bond surface mount components to pads on printed circuit boards. The paste is applied by nozzle, stencil printing or syringe.
- SST – Silkscreen Topcoat (extension: board.gto). Silkscreen is a layer of paint used to mark components, brands, logos, etc.
- BOT – Bottom layer of copper (extension: board.gbl). Marks the copper traces on the underside of the board.
- SMB – Solder Mask Bottom Layer (extension: board.gbs).
- SPB – Solder Paste Bottom Layer (extension: board.gbp).
- SSB – Silk Screen Bottom (extension: board.ghbo).
- Inner layer for signals and currents.
2. NC drill file: orientation of the drill holes on the board (extension: board.txt).
3. File for selection and placement.
4. IPC 356 netlist file.
5. The ODB++ file (opens database). Information exchange between the design phase and the manufacturing phase.
6. PDF file with schematics and layout.
7. PDF file with assembly drawings.
A Good PCB layout design process transforms your circuit idea into a manufacturable physical board. From the initial schematic to final Gerber files,
each step requires attention to detail, design tools, and engineering insight. Below is a breakdown of the typical PCB layout design steps used by professionals and teams across industries.
1. Schematic Reception
The process begins by receiving the validated circuit schematic. This file defines the logical electrical connectivity and component relationships that will drive the layout.
2. CAD Library Setup
Designers import or build CAD libraries that include footprints, pad stacks, 3D models, and electrical constraints. These are assigned to the components in the schematic.
3. Component Placement
Components are physically arranged on the PCB outline. Placement considers functionality, electrical performance, manufacturability, and heat zones.
4. Routing Traces
Electrical connections (nets) are routed as copper traces. Designers optimize path lengths, avoid interference, and manage signal integrity during this phase.
5. Design Rule Check (DRC)
A critical validation step where the CAD tool checks all nets, clearances, trace widths, and component distances against design rules and constraints.
6. Generate Gerber Files
Once layout is complete and validated, the board is exported into Gerber files—standard manufacturing outputs that define each layer of the PCB for fabrication.
When your design is complete, your fabrication files must be sent to DFM for review and quotation before proceeding to fabrication and assembly.
Complete and clear manufacturing instructions will help ensure that this PCB design can be produced anywhere.
