Define each board's task
Separate the flight controller, electronic speed controller, radio, navigation and payload functions in the initial block diagram. Decide which belong together based on packaging and noise relationships. A compact connector between boards may be preferable to forcing incompatible thermal and sensor constraints into one layout.
ST's drone ESC reference design illustrates a distinct motor drive assembly that communicates with a flight control unit. Treat this as an architecture example, not a universal power rating or construction specification for another design.
Place the sensors with the mechanics
Show sensor axes, mounting points and expected board support in mechanical CAD. Review cable and connector forces near the sensing region. Preserve the physical orientation in documentation so calibration and firmware teams are working from the same coordinate system.
Reserve space around navigation and radio circuitry according to the selected device and antenna guidance. Stacking another board above the controller can change the surroundings substantially; include that board, its cables and any shields in prototype measurements.
Compare integration against observability
Combining functions can reduce mass and connectors while making diagnosis harder. Provide accessible measurements for supply behavior and critical interfaces during early builds. If production packaging removes those points, specify a fixture or staged test that preserves the needed evidence.
- Map motor and battery current paths independently of signal escape.
- Record sensor orientation and mounting arrangement.
- Check antenna and navigation regions in the complete board stack.
- Retain programming, recovery and configuration identification access.
Validate with representative electrical activity
Compare sensor readings and communications under controlled changes in power conversion and motor electronics activity, using the project's approved test setup. Keep propulsive testing within the team's established procedures. The PCB review should identify what must be measured without assuming a bench connectivity check proves flight readiness.
Track assembly weight, cable arrangement, board revision and firmware settings with results. A later mass reduction can change mechanical support or thermal behavior even when the electrical schematic remains the same.
Adjacent-layer access, one connection at a time
Dielectric · geometry + material
Core or build-up dielectric
Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.
Common questions
Does HDI make a drone board more reliable?
It can solve routing constraints, but reliability depends on the actual construction, assembly, environment and verification. Density alone is not evidence of reliability.
Should an IMU be placed wherever routing is easiest?
No. Its orientation, mounting environment and relationship to board strain and heat belong in the placement review alongside electrical routing.
References & further reading
Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.