From idea to product: how electronic device development works

Every electronic device, from a simple sensor to an industrial controller, goes through similar development phases. The differences lie in the scope, not in the sequence. If you understand these phases, it is easier to plan the budget, deadlines and risks – whether you develop the device yourself, with a partner or commission an external developer. Below we describe a typical project as we run it at Selektronik, pointing out where projects most often get stuck.

Phase 1: Requirements and specification

Everything starts with the question of what the device must do and under what conditions. A good specification is not a long document, but it must answer:

• Function: which inputs, outputs and interfaces (USB, RS-485, Ethernet, Bluetooth, LoRa), what measurement accuracy.
• Power: battery, USB, 24 V industrial, 230 V mains; the expected battery life.
• Environment: temperature range, humidity, dust, vibration, indoor or outdoor use, required IP protection.
• Regulations: CE (EMC, LVD, RED for radio), RoHS, possibly automotive or medical standards.
• Quantities and target price: 20 units for an internal project or 20,000 units for the market means a completely different architecture.
• Deadline: when the first prototype must work and when the product must be on the market.

The mistake we see most often: requirements change after the board has already been made. Every change at this stage costs an hour of discussion; the same change after the prototype costs a new round of board manufacturing.

Phase 2: Architecture and component selection

The requirements produce a block diagram: microcontroller, power section, sensors, communication, protection. Next comes the selection of key components, where we consider:

• availability and life cycle (we do not choose components marked "not recommended for new designs"),
• the price at the target quantity,
• the availability of development tools and libraries,
• the existence of alternatives (second source) for critical parts.

At this stage we also decide on the number of PCB layers, the assembly technology (SMT, THT, mixed) and the type of enclosure. The result is an estimate of the material cost (BOM cost), which we compare with the target price.

Phase 3: Schematic

The schematic is an exact description of every connection. We draw it in a professional tool (KiCad, Altium) with libraries in which every component has a verified symbol, footprint and manufacturer part number. Good practice:

• the schematic is split into several sheets by functional block,
• each block has comments on its purpose and the key calculations (dividers, filters, current limits),
• protection (TVS diodes, fuses, ESD) is provided on all external connections,
• test points and the programming interface are part of the schematic, not an afterthought.

Before the layout we review the schematic with an ERC (Electrical Rules Check) and, ideally, with a colleague who does not know the project.

Phase 4: PCB layout

The layout turns the schematic into a physical board. This is where the EMC behaviour, the thermal conditions and whether the board can be assembled at all are decided. The sequence:

1. Define the outline and the mechanical constraints (screw holes, connector positions, component heights relative to the enclosure).
2. Place the components by functional block: the power supply away from analogue sections, the antenna at the edge, the drivers close to the connectors.
3. Route the critical connections first: power, high-speed signals, differential pairs, analogue signals.
4. Copper pours for ground, thermal vias, a DFM review.
5. DRC and export of the Gerbers, BOM and placement file.

At the same time the 3D model of the enclosure starts to take shape, because board and enclosure adapt to each other: the positions of LEDs, buttons and connectors must match to a tenth of a millimetre.

Phase 5: Prototype

The first prototype is not meant to be perfect; it is meant to reveal errors as quickly as possible. We typically build 3 to 5 boards, assemble them and then:

• check the power supply without the components an error could destroy (staged power-up),
• load basic firmware and check communication with all peripherals,
• measure current consumption, temperatures and signals with an oscilloscope,
• check the mechanical fit in a 3D-printed enclosure.

Almost every first prototype needs a few fixes: a wrong footprint, a swapped connector pin, not enough filtering. That is normal and cheaper than waiting for perfection. It is good practice to plan two board iterations before the series.

Phase 6: Firmware and testing

The firmware is developed in parallel with the board. We plan for updates (a bootloader), safe behaviour during power loss and diagnostics that production can use for testing.

Testing covers:

• Functional testing: every requirement in the specification has a test.
• Environmental testing: operation at the temperature limits, humidity and vibration, in a climate chamber if needed.
• Reliability tests: long-term operation, power cycling, ESD on the connectors.
• EMC pre-compliance measurements: emissions and immunity in a lab or with in-house equipment before the device goes to official testing.

Phase 7: CE marking and EMC

Every device sold in the EU needs the CE marking and a declaration of conformity. For electronics the most important are:

The manufacturer can issue the declaration of conformity itself, based on tests in an accredited laboratory or its own measurements. Using certified radio modules greatly simplifies the RED part. EMC testing costs range from a few hundred to a few thousand euros, depending on the scope; a failed test and a second visit are the reason we take EMC into account already in the layout.

Phase 8: Enclosure and mechanics

For prototypes we 3D print the enclosure (FDM or SLA), which lets us check ergonomics and assembly within a day. For series we choose between:

• 3D printing (up to a few hundred units),
• CNC-machined aluminium (small series, robustness, EMC shielding),
• adapting a standard enclosure (Hammond, Bopla, OKW) with CNC cut-outs and printing,
• plastic injection moulding (from about 1000 units; the tool is an initial investment).

In every case the tolerances, IP protection, connector access and heat dissipation are key; we describe them in detail in a separate article on 3D enclosure design.

Phase 9: Preparing for series production

Before the product goes into series production we prepare the production documentation: final Gerbers, a BOM with alternatives, component placement data, assembly drawings, test instructions and a test fixture (test jig) that checks every unit within seconds. A pilot series (e.g. 20 to 50 units) validates the whole process, and then the series follows.

For the series we also define traceability (serial numbers, revisions), packaging and instructions. Every change to the product after this point goes through change control, so that production always knows which revision is valid.

Typical timeline

In total, from about three months for a simple device to a year for a more complex product with a radio and certification.

Need help?

At Selektronik we take projects through all of the phases described: from specification and schematic, through PCB layout and prototype assembly, to the 3D enclosure, certification preparation and series production. If you have an idea or an existing device you want to improve, write to us at info@selektronik.si or have a look at our product development services; for your prototype boards, the PCB configurator shows a price estimate right away.