From Prototype to Series Production: How to Prepare Your Device So It Doesn’t Get Stuck Along the Way

The prototype works, the investor is happy, the first customers are waiting. This is the moment when many teams assume the hardest part is behind them. Yet between a working prototype and a device that can be produced repeatably in thousands of units there is still a considerable way to go. After thirty years of launching production for a range of industries, we know where that road most often gives way. This article is about how to avoid those spots.

Why a prototype is not yet a product

A prototype is built to prove that an idea works. Nobody building one is thinking about whether the components will still be available in two years, whether a machine will be able to place the parts without collisions, or how many seconds it will take to test a single unit. And rightly so; at that stage other things matter.

The problem begins when the prototype documentation goes to production without any changes. A hand-soldered board forgives things a production line will not: components placed too close together, no fiducial marks for the machines, parts available only from a single seller on an auction site. That is why the first step should always be a thorough review of the documentation from a manufacturing perspective, known in the industry as DFM (Design for Manufacturing).

Documentation review: where the biggest savings are made

As part of preparing a design for production, we review the schematic, the board layout and the bill of materials before anything reaches the shop floor. We look for answers to a few questions. Can the board be assembled automatically, quickly and without operations that require acrobatics? Is any component over-specified for the job it performs? Does the design contain parts the manufacturer is no longer developing?

The result is often changes that seem minor but have major consequences: a different package for the same IC, a surface-mount connector instead of a through-hole one, additional test points that later shorten the inspection of every unit. The cost of such corrections before a series starts is small. The same corrections introduced after the first batch has been produced cost many times more.

Components: availability can matter more than price

The semiconductor shortages taught the industry humility. A design based on a component that will disappear from the market in a year is a time bomb, which is why when reviewing a bill of materials we look not only at price but also at the life cycle of the parts and possible substitutes. It is good practice to specify alternatives for key ICs already at the design stage, so that a potential swap does not require redesigning the board.

We work with a network of distributors, so as part of our component sourcing service we handle purchasing and keep track of delivery dates, and we record the origin of every component batch in our ERP system. For printed circuit boards we additionally offer storage, so you can order a larger, cheaper batch of PCBs and draw on it from stock for subsequent assembly runs.

Firmware ready for production, not just for a demo

Embedded software also has its “prototype” and “production” versions. In production, firmware must be quick and automatic to flash, the device should be able to report on its own that something is wrong with it, and software versions must be unambiguously linked to device batches. Our team writes embedded software for STM32, AVR, Nordic and ESP32 platforms and designs it from the outset with these requirements in mind.

On top of that come functional tests: every unit coming off the line should be checked according to a repeatable procedure, and the test result recorded. A well-designed test procedure is often the difference between a return rate of a fraction of a percent and a wave of returns that eats up the entire margin.

Pilot run: the dress rehearsal before launch

Even after the best review, it is worth starting with a short pilot run of a few dozen or a few hundred units, produced exactly as the target production will be. The pilot verifies everything at once: documentation, the assembly process, test procedures and packaging. The lessons learned are fed back into the documentation, and only then does full-scale production begin.

It is also a good moment to establish a realistic delivery rhythm. Series production is not a single order but a process that should keep pace with sales without tying up cash in excessive inventory.

Documentation that lives alongside the product

Finally, the least glamorous and most notoriously neglected point: the documentation must be kept up to date. Every component change, board layout revision or new firmware version should have its own number, date and reason. When, two years down the line, you need to explain a difference in behaviour between devices from different batches, a proper change history is priceless. At Convel this is enforced by a system in which every production batch is linked to a specific version of the documentation.

If you have a working prototype and are wondering about the next step, get in touch with us. We will review the documentation, tell you honestly what is ready and what is worth improving, and help you plan the move into production. And for how to evaluate contract manufacturers in general, see our separate guide on choosing an EMS partner.