PCB Design

From Bespoke Robot Society
Jump to navigation Jump to search
PCB Design
Expressing electronics knowledge into custom circuit boards for professional, integrated robot designs
Difficulty Range Beginner to Advanced
Time to Basic 3-6 weeks
Essential Tools KiCad (free), PCB manufacturer account (JLCPCB, PCBWay)
Optional Tools Caliper for component measurements, PCB design rule checker
Get Started KiCad Tutorial
Unlocks (Basic) Custom sensor breakout boards, simple robot PCBs
Unlocks (Advanced) Multi-layer integrated robot boards, motor controllers, high-speed designs

PCB Design is the competency of translating circuit schematics and electronics knowledge into manufacturable printed circuit boards (PCBs). In robotics, custom PCBs transform breadboard prototypes into durable, compact, and professional designs. This competency specifically covers expressing goals and comprehension from Electronics into new custom boards and getting them assembled by a board house.

PCB design is distinct from Electronics (understanding how circuits work) and Soldering (assembling components onto boards). This competency focuses on designing the board itself: creating schematics, laying out traces, selecting footprints, and generating manufacturing files.

Why PCB Design Matters for Robotics

Custom PCBs elevate your robot from prototype to production:

  • Integration - Combine sensors, motor drivers, and microcontroller on one board
  • Reliability - No loose breadboard connections or flying wires
  • Compactness - Shrink your electronics to fit tight spaces
  • Reproducibility - Order 5, 10, or 100 identical boards from manufacturers
  • Professionalism - Clean, documented designs you can share or sell

Without PCB design skills, you're limited to pre-made modules and breadboards. With PCB design, you can create exactly the board your robot needs.

Skill Progression

Beginner (First PCB)

Skills you need to design and order your first PCB:

  • Schematic capture - Draw circuit diagrams in KiCad
  • Component symbols - Find or create schematic symbols for parts
  • Footprint assignment - Match components to their physical footprints
  • PCB layout basics - Place components and route traces
  • Design rules - Set trace width, clearance, via size
  • Gerber generation - Export manufacturing files
  • Ordering from manufacturers - Upload to JLCPCB/PCBWay, select options

Unlocks:

  • Simple breakout boards (sensor modules, connector adapters)
  • Through-hole robot PCBs (like SimpleBot main board)
  • LED circuits and indicator panels

Tutorials: KiCad Tutorial

At this level you can:

  • Design simple 2-layer through-hole PCBs
  • Order boards from online manufacturers
  • Create breakout boards for sensors and modules
  • Understand SimpleBot's PCB design

Intermediate (Production-Ready Designs)

Skills for designing robust, manufacturable PCBs:

  • 4-layer boards - Add internal power and ground planes
  • SMD components - Use surface-mount devices for compact designs
  • Trace width calculations - Calculate trace width for current capacity
  • Component library management - Create custom symbols and footprints
  • Design rule checks (DRC) - Catch errors before manufacturing
  • Silkscreen design - Add labels, logos, version numbers
  • Bill of Materials (BOM) - Generate parts lists for assembly
  • PCB panelization - Arrange multiple boards on one panel

Unlocks:

  • Integrated robot main boards (MCU + sensors + motor drivers)
  • Custom motor controller PCBs
  • Power distribution boards with multiple voltage rails
  • Compact sensor arrays

Tutorials: Advanced KiCad techniques, PCB layout best practices

At this level you can:

  • Design compact, reliable robot PCBs
  • Use SMD components to reduce board size
  • Create production-ready designs with proper documentation
  • Work with PCB assembly services (PCBA)

Advanced (High-Performance Designs)

Skills for specialized and high-performance PCBs:

  • High-speed design - Controlled impedance, differential pairs, length matching
  • Thermal management - Heat dissipation, thermal vias, copper pours
  • EMI/EMC design - Shielding, filtering, grounding strategies
  • RF design - Antenna design, impedance matching, transmission lines
  • Flex and rigid-flex PCBs - Flexible circuits for moving parts
  • PCB assembly optimization - Design for manufacturability (DFM)
  • Multi-board systems - Stackable boards, connectors, modularity

Unlocks:

At this level you can:

  • Design high-speed communication boards
  • Create custom motor controllers with current sensing
  • Design RF and antenna boards
  • Optimize designs for cost-effective mass production

Learning Paths

Path 1: First PCB Designer (Beginner)

  1. Complete Electronics Fundamentals - Understand circuits before designing PCBs
  2. Start with KiCad Tutorial - Design a simple LED or sensor breakout board
  3. Order your first PCB from JLCPCB (5 boards for $2 + shipping)
  4. Assemble and test your board

Result: You can design simple 2-layer PCBs and order them from manufacturers.

Path 2: Robot PCB Designer (Intermediate)

  1. Complete Path 1 (First PCB Designer)
  2. Study SimpleBot PCB design (schematic and layout files)
  3. Design a custom breakout board for a sensor or module
  4. Learn SMD component soldering (Soldering)
  5. Design a robot main board integrating MCU, sensors, and motor driver

Result: You can design integrated robot PCBs with SMD components.

Path 3: Advanced PCB Designer

  1. Complete Path 2 (Robot PCB Designer)
  2. Study high-speed design principles (impedance control, signal integrity)
  3. Design a 4-layer board with internal power/ground planes
  4. Use PCB assembly services (PCBA) for SMD assembly
  5. Design a specialized board (motor controller, camera interface, RF module)

Result: You can design production-ready, high-performance PCBs for any robot application.

Essential Concepts

PCB Layers

PCBs are built from copper layers separated by insulating material:

  • 2-layer - Top and bottom copper (beginner level)
  • 4-layer - Top, bottom, and two internal layers (typically power and ground)
  • 6+ layers - High-speed designs, dense routing

Why more layers?

  • Better power distribution (dedicated power planes)
  • Reduced noise (solid ground plane)
  • More routing space for complex designs

Trace Width and Current Capacity

Trace width determines how much current a trace can carry:

  • Thin traces (0.2mm) - Signal traces, low current (<100mA)
  • Medium traces (0.5mm) - General purpose (100mA - 500mA)
  • Thick traces (1-2mm) - High current (1A - 3A)
  • Copper pours - Very high current (5A+), heat dissipation

Rule of thumb: 1mm trace width per 1A of current (for 1oz copper, typical PCB)

Vias

Vias are holes that connect copper layers:

  • Through-hole vias - Connect all layers (most common)
  • Blind vias - Connect outer layer to internal layer
  • Buried vias - Connect internal layers only

Use vias to:

  • Route traces to other layers
  • Connect component pads to internal planes
  • Improve heat dissipation (thermal vias)

Design Rules

Design rules ensure manufacturability:

  • Minimum trace width - Typically 0.15mm - 0.2mm
  • Minimum clearance - Gap between traces (typically 0.15mm - 0.2mm)
  • Minimum via size - Drill diameter (typically 0.3mm)
  • Soldermask expansion - Gap around pads for solder mask

Violating design rules = manufacturing errors or rejected boards

Footprints

Footprint = physical pad layout for a component:

  • Through-hole - Holes for component leads (resistors, DIP ICs)
  • SMD - Surface pads for surface-mount components (0805 resistors, QFN ICs)

Getting footprints right is critical:

  • Wrong footprint = component doesn't fit
  • Check datasheets for recommended footprints
  • Test footprints with calipers before ordering

PCB Design Workflow

Step 1: Schematic Design

  1. Start with a tested breadboard prototype
  2. Draw schematic in KiCad schematic editor
  3. Add component symbols from libraries
  4. Connect components with wires (nets)
  5. Add power symbols (VCC, GND)
  6. Annotate components (assign reference designators: R1, C2, U3)
  7. Run electrical rules check (ERC)

Step 2: Footprint Assignment

  1. Assign footprints to all components
  2. Verify footprints match physical parts (check datasheets)
  3. Create custom footprints if needed
  4. Generate netlist (connects schematic to PCB layout)

Step 3: PCB Layout

  1. Import netlist into PCB editor
  2. Define board outline (cut shape)
  3. Place components logically (MCU in center, connectors on edges)
  4. Route power traces first (wide traces for high current)
  5. Route signal traces
  6. Add ground plane (copper pour connected to GND)
  7. Add mounting holes for screws
  8. Design silkscreen labels (component names, polarity markers)

Step 4: Design Rule Check and Export

  1. Run design rule check (DRC) to find errors
  2. Fix all violations (spacing, trace width, unconnected nets)
  3. Generate Gerber files (manufacturing files)
  4. Generate drill files
  5. Optionally generate assembly files (BOM, pick-and-place)

Step 5: Manufacturing

  1. Upload Gerber files to manufacturer website
  2. Select options (board size, quantity, color, finish)
  3. Review preview and pricing
  4. Place order
  5. Wait 1-2 weeks for delivery

Tools and Equipment

Essential Software

  • KiCad (Free, open-source) - Full-featured PCB design suite
    • Schematic editor
    • PCB layout editor
    • Footprint editor
    • 3D viewer
    • Available for Windows, Mac, Linux

Alternative Software

  • Eagle (Free for hobbyists, limited board size) - Popular alternative
  • EasyEDA (Free, web-based) - Integrated with JLCPCB ordering
  • Altium Designer ($$$$) - Professional industry standard
  • Fusion 360 Electronics (Subscription) - Integrated with CAD

BRS recommendation: Use KiCad (free, powerful, no limitations)

Online PCB Manufacturers

  • JLCPCB - $2 for 5 boards (100mm × 100mm), fast shipping, PCBA services
  • PCBWay - Similar pricing, good quality, responsive support
  • OSH Park - USA-based, purple boards, slower but high quality
  • Seeed Studio - Fusion PCB service, good for prototypes

Physical Tools

  • Caliper ($15-30) - Measure component dimensions for footprint verification
  • PCB ruler ($5-10) - Check trace width and component spacing
  • Magnifying glass ($10-20) - Inspect SMD pads and trace spacing

Common Pitfalls

  • Wrong footprints - Always verify footprints with datasheets and calipers before ordering
  • Insufficient trace width - Narrow traces overheat and fail under high current
  • Missing ground plane - Increases noise, poor power distribution
  • No silkscreen labels - Difficult to assemble and debug without labels
  • Ignoring DRC errors - "It'll probably work" usually means it won't
  • Placing components too close - Difficult or impossible to solder
  • Forgetting mounting holes - Can't attach board to robot chassis
  • No decoupling capacitors - ICs behave erratically without local power filtering

SimpleBot PCB Example

The SimpleBot main board is an excellent beginner-level PCB design:

  • 2-layer through-hole design - Easy to assemble with basic soldering skills
  • Clear component layout - Components labeled and logically placed
  • Designed in KiCad - Source files available in repository
  • Motor driver integration - TB6612FNG motor driver IC
  • Sensor headers - Connectors for line sensors and encoders
  • Power regulation - MP1584 buck converter footprint

Study the SimpleBot PCB files to learn:

  • How to layout a robot main board
  • Component placement strategy
  • Trace routing for power and signals
  • Silkscreen labeling best practices

Files available at: `./simplebot/kicad/` (schematic and PCB layout)

First PCB Project Ideas

Start with simple projects to build confidence:

Beginner Projects

  • LED circuit board - Power LED, resistor, battery connector (learn basics)
  • Sensor breakout board - IR sensor, headers, mounting holes (learn footprints)
  • Power distribution board - Voltage regulator, capacitors, terminal blocks (learn power design)

Intermediate Projects

  • Motor controller board - H-bridge IC, terminal blocks, logic inputs
  • Sensor array board - Multiple IR sensors, multiplexer, single I2C output
  • Robot main board - MCU, sensors, motor driver, power regulation (like SimpleBot)

Advanced Projects

  • Custom IMU board - Accelerometer/gyro IC, level shifters, SMD components
  • Camera interface board - High-speed serial, MIPI interface, impedance control
  • Wireless module board - ESP32, antenna, RF design considerations

Design for Manufacturing (DFM)

Make your boards easier to manufacture and assemble:

  • Use standard components - Common resistor values, standard ICs
  • Add test points - Pads for probing signals with multimeter/oscilloscope
  • Label polarity - Mark + and - for electrolytic capacitors, diodes, connectors
  • Add version number - Silkscreen text with version/date
  • Include fiducial marks - Alignment marks for automated assembly
  • Add mounting holes - 3mm or M3 holes in corners
  • Keep components on one side - Easier assembly (both sides only if necessary)

PCB Assembly Options

Hand Assembly (DIY)

  • Solder components yourself
  • Requires Soldering skills
  • Cost: $0 (just your time)
  • Best for: Through-hole, small quantities, learning

PCB Assembly Services (PCBA)

  • Manufacturer assembles components onto PCB
  • Requires BOM (bill of materials) and pick-and-place files
  • Cost: Setup fee + component cost (economical for >10 boards)
  • Best for: SMD components, production runs

Popular PCBA services:

  • JLCPCB Assembly - Large component library, economical for prototypes
  • PCBWay Assembly - Good for custom components
  • Seeed Studio - Fusion PCBA service

Tutorials and Resources

BRS Tutorials

  • KiCad Tutorial (Beginner) - Complete first PCB design walkthrough
  • Electronics (Beginner to Advanced) - Understand circuits before designing PCBs
  • Soldering (Beginner) - Assemble your PCBs after manufacturing

Component and Robot Pages

  • SimpleBot - Study the PCB design (files in `./simplebot/kicad/`)
  • TB6612FNG - Motor driver IC used in SimpleBot PCB
  • Raspberry Pi Pico - Microcontroller footprint and pinout
  • MP1584 - Buck converter module for power regulation

External Resources

Related Competencies

  • Electronics - Understand circuits before designing PCBs
  • Soldering - Assemble components onto PCBs
  • Software - Program the microcontrollers on your PCBs
  • 3D Printing - Design enclosures and mounts for your PCBs
  • Mechanics - Integrate PCBs into robot chassis

See Also

Retrieved from "https://wiki.bespokerobotsociety.org/index.php?title=PCB_Design&oldid=79"