Draw the installed system boundary

Specify the sensor cables, power source, enclosure material, mounting method and intended antenna arrangement. A bench powered wireless node and one installed inside a metal machine cabinet are different systems even when they share a schematic.

Analog Devices' MAXREFDES9001 illustrates a sensor node, gateway and cloud architecture. The board review should therefore distinguish local measurement quality, radio connectivity and upstream service behavior rather than interpreting every missing reading as a PCB fault.

Assign space according to interface risk

Keep cable entry and protection placement visible before packing the processor region. Show how disturbance current is intended to return, and review connectors with the mechanical team for strain relief and tool access. HDI routing should not consume reserved separation or service space.

For a battery node, make a current measurement plan that can capture sleep and transmit activity. For a powered gateway, evaluate simultaneous interface traffic and processing load. These two products may require very different power and thermal priorities.

Choose a maintainable compact layout

Compare replacing a large package with a dense package against the resulting via construction and inspection burden. A few millimeters of board reduction may not help if the terminal block or antenna already defines the enclosure size. State the actual enclosure or performance benefit before increasing process complexity.

  • Identify field accessible connectors and programming recovery paths.
  • Review antenna behavior in the intended cabinet and mounting position.
  • Document sensor reference and shielding connections.
  • Record permitted material and component substitutions for long service programs.

Prototype the installation, not just the board

Build an installation representative setup with cable lengths, power source and enclosure. Capture baseline sensor readings before switching radios, outputs or nearby equipment. Where environmental testing is required, agree on its conditions and acceptance criteria through the product's engineering process.

Plan how firmware and board revisions will be identified after deployment. A service team should be able to distinguish a changed sensor calibration, a new radio layout and a revised connector pinout without opening an undocumented hardware mystery.

DESIGN NOTE / SCHEMATIC

Adjacent-layer access, one connection at a time

Signal copper

Dielectric · geometry + material

Reference copper

Core or build-up dielectric

Signal copper

Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.

Real smartphone circuit board illustrating compact component placement
Illustrative compact electronics example; not a product-specific manufacturing sample. © Raimond Spekking / CC BY-SA 4.0. Credits & license.

Common questions

Is HDI necessary for a simple wireless sensor?

Often it is not. Confirm whether package escape or enclosure geometry requires it. Standard routing can be preferable when connectors or the antenna dominate size.

Should radio tests use an open board?

Use open board measurements for diagnosis, then test the intended enclosure and installation. Mounting metal, cables and nearby equipment are part of the practical RF environment.

References & further reading

Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.