A prototype that works on the bench is an exciting moment, but it is only half the way. Between a prototype and a product coming off a production line there is a gap that surprises many companies and entrepreneurs. These are the seven mistakes we see most, and how to avoid them.
1. Parts you cannot buy
In a prototype you choose the part that works best. In production you discover it has a 40-week lead time, or that the manufacturer announced end-of-life (EOL). Solution: check availability and life cycle already when selecting components, and define an alternate for every critical part.
2. No production test jig
In the lab the engineer tests every board by hand. In the factory there is no engineer, and there are hundreds of boards. Solution: design test points on the PCB, and build a test jig and test firmware that check every board in seconds.
3. No way to update firmware in the field
A bug found after the product reaches customers means collecting every unit, or visiting every customer. Solution: design a bootloader and an update mechanism from the start: USB, BLE, Wi-Fi or even LoRa. We have seen projects where adding remote updates after the fact, to a network of about 150 units in the field, required complex design because of the limits of the existing hardware.
4. Ignoring certification until the end
Failing an EMC test after the board is already in production means a redesign. Solution: lay out the board to meet EMC requirements from the start, and run a pre-compliance test on the prototype.
5. Component prices not checked at volume
A part that costs a dollar in the prototype can be 30% of the product cost. Solution: a BOM with prices at the expected production volume, and a check of cheaper alternates before freezing the design.
6. A design that doesn't fit the assembly line
Parts placed too densely, parts on both sides of the board for no reason, or through-hole parts that require hand soldering. All of these make every unit more expensive. Solution: a DFM (design for manufacturing) review with the factory before ordering the batch.
7. Skipping the pilot
Going straight from a prototype to a thousand units is a gamble. Solution: a small batch of 10–50 units for real use, where problems of heat, noise, assembly and users show up before they are multiplied by a thousand.
Summary
Most of these mistakes are very cheap to prevent at the design stage, and very expensive to fix after production. It helps a lot when the engineer who designed the prototype also stays with it through production, because they know every decision that was made and why. If you have a working prototype and are heading to production, we'll be happy to go over it with you.
Written by Roman Alperovich, founder and lead engineer at ProtoMakers.