An electronic product, from idea conceiving to finished marketable product, passes through various iterative steps like requirement specifications, circuit design, bread boarding of critical circuit sections, design reviews etc. . When a hardware or firmware that is built on a prototype PCB the manufacturers or employers do ask to build a prototype of that hardware. This prototyping or experimental work leads to a proof of concept of that hardware. Generally a circuit on a PCB needs enough components functional testing and verification before it is qualified and passed for production.
In PCBs the prototyping occurs at very earlier stages after circuit design, layout and PCB fabrication. The experimentation in prototyping stage assures that the hardware meets the specifications. The goal is to verify that the product will be functional, accurate enough as per specifications, throughput efficient and environment friendly when deployed in the field. This stage may take more than one iteration if the PCB underperforms. The benefit of prototyping is to reveal and remove the shortcomings which may cause product failure, if otherwise, were ignored. The keypoints which are kept in mind during prototyping are under or over designed circuits which effect functionality and cost respectively, overhead of assembly time and cost, practical limitations of components which are not found in simulation, PCB dimensions and bill of material cost, placement inside mechanical enclosure and heat dissipation etc. Another benefit of a prototype PCB mounted inside a prototype mechanical enclosure may be used to get user feedback.
Generally, the large production houses, only a few PCBs are manufactured for prototyping to reduce cost and manufacturing time. This is the final PCB if works in the first run i.e., the same PCB goes for final production. However, if the prototype PCB does not qualify all of the required specifications or is not acceptable, the problem is probed by conducting a detailed design review. After design review, a new iteration starts by doing the necessary amendments in design at the appropriate level i.e. circuit design, PCB layout, PCB material selection etc.
Whereas the small or with low budget constraint setups go towards low cost PCB fabrication either as a single layer or divided and multiple single layer PCBs (ignoring the actual dimensions) and finally interconnecting them with cable and connectors method. This method suits to hobbyists, general household items and gadgets producers. This method provides a low cost solution to product specifications and validation. Once the prototype is built successfully a last iteration goes towards the final PCB with exact dimensions for final testing which is almost the production PCB in many cases.
Figure: A PCB troubleshooting after manufacturing and assembling