Tank-Shaped PCB

Circuit Design

The process began with creating a schematic that defines how the circuit functions.
Components used:

• Microcontroller (XIAO RP2040)

• LEDs (output indicators)

• Resistors (current limiting)

Steps involved:

• Defined power connections (VCC and GND)

• Connected LEDs to GPIO pins through resistors

• Ensured correct polarity of LEDs

• Organized schematic for readability

This stage ensured that the circuit logic was correct before moving into physical design.

Component Footprints — Digital to Physical Mapping

Each component in the schematic was assigned a footprint.

This defines:

• pad size and spacing

• exact physical dimensions of components

• soldering contact areas

Care was taken to:

• select correct SMD packages

• match footprint orientation with real components

• avoid mismatches that could cause assembly failure

This step is critical because errors here directly affect fabrication and soldering.

PCB Layout — Tank Form Development

The board was developed in a tank-shaped form, which required careful spatial planning. Components were arranged to fit within the geometry, and traces were manually routed to maintain clear and efficient connections. This stage highlighted the relationship between circuit logic and physical structure, where layout decisions directly affect both performance and form.

• Traces were manually drawn

• Short and direct connections were prioritized

• Crossovers were avoided due to single-layer board constraints

• Trace width and spacing were controlled for milling

Design Rules & Validation

Before fabrication, the design was validated:

• checked connections (DRC)

• ensured trace width and spacing were manufacturable

• exported files for milling

The layout was then exported and converted into toolpaths. Parameters such as tool diameter, cut depth, and offset values were defined to prepare separate operations for trace milling and board cutting. This stage bridged the digital design with machine execution.

File Preparation — Toolpath Generation

Toolpaths were generated considering:

• tool diameter

• cut depth

• minimum trace width and spacing

Separate toolpaths were generated for:

• trace milling

• board outline cutting

CNC Milling — Fabrication

The board was fabricated using a CNC milling machine on a copper-clad board.

Process:

• Board fixed securely to machine bed

• Tool zeroed on X, Y, and Z axes

• Trace milling performed first (shallow cut)

• Outline cut performed after (deeper cut)

Challenges faced:

• incorrect depth could remove traces completely

• insufficient depth could leave copper connections

• alignment had to be precise

The result was a physically milled PCB with exposed copper traces.

Assembly — Soldering Components

Components were assembled onto the PCB using soldering.

• applied solder to pads

• placed components using tweezers

• heated joints to secure components

Important considerations:

• correct orientation of LEDs and microcontroller

• avoiding solder bridges between pads

• maintaining clean joints

This stage required precision and steady control.

Testing & Debugging — Functional Validation

Checked connections and verified that the board functions as intended.