The creation of a device prototype is a very important and, oftentimes, necessary stage of electronic product development. Methods and approaches employed in the electronic prototyping process depend heavily on resources provided by a client; as well as on particular tasks to be solved with the help of a prototype.
When we say resources, we mean time and money. Everything’s quite clear in this aspect: if the resources are scarce (which is, usually, the case), one should try to create an electronic prototype that would resemble the end product as closely as possible. In fact, in such a case, a prototype would serve as an alpha-version of the end product which a designer develops for the sake of their own peace of mind. Sometimes, a client wishing to save money on product design and electronics prototyping services, sets such limits that the timeframe/budget become insufficient. What they don’t realize is that they might even lose more due to such a decision.
Obviously, a prototype very similar to the end product is a great thing, but it’s also time-consuming. Therefore, a balance between quality and a projecting timeframe should be achieved. For instance, a project can involve software development, which can take a lot of time. In this case, it only makes sense to develop a core system, which includes a microcontroller featuring a sufficient number of inputs/outputs, analog signals, and particular integrated circuits for interaction. In such a manner, the acceleration of the development process is achieved by neglecting (to an adequate extent) miniaturization and simplifying circuit board routing. Of course, it is likely not a good thing to neglect the quality of the arrangement while working on the prototype electronics that involve DDR3 or antennae. That’s why one must assess beforehand in what way any employed simplifications would influence the performance capabilities of the prototype.
The crucial element of prototype manufacturing and electronic device design as a whole includes the printed circuit board. The best option here is the plant-manufacturing method, with the obvious advantage of this approach being quality, while the downside includes time expenditures and high costs. Alternatives include the photoresist or toner transfer methods. The latter technique is cheap and fast but is limited in a bunch of aspects.
Firstly, only a single or double-sided board can be created via this method. Secondly, it features more demanding requirements as to clearances, tracking widths, via diameter, etc. Speaking from experience, we can say that the toner transfer method makes it possible to create a board with a 0.2mm track width, 0.2mm clearance, and 1.0mm microvias diameter. Boards that are more complex can also be manufactured, but the process would be very difficult - and you should forget about BGA entirely. Lastly, one must keep in mind that the microvias would be produced by an all-around soldering of the conductor passing through an aperture, not galvanically. These limitations bring us to the conclusion that only very simple boards can be manufactured via the discussed method.
Another thing to keep in mind when designing an electronic prototype is the ability to use the selected components in the serial product. Let’s consider the following case to give you an example: the manufactured prototype passes the test but certain components featured by it cannot be identified or bought in large numbers. Some components purchased from local distributors are cheaper versions of brand products with just slight distinctions. This includes cheap Chinese buttons, batteries, passive components, etc. At times, this isn’t critical, as the replacement can still take place - but not always. So, when employing the capacities of another component, ask yourself: will I be able to purchase this particular component in the future?
In addition to all the above-mentioned specifics, notice also that it’s useful and convenient to have separate libraries of components for plant-manufacturing and prototyping. The plant-manufacturing library components must feature layers covered with solder mask, solder paste, and, as a whole, should preferably correspond with the IPC-7351 standard. Toner transfer method components mustn’t have microvias in pads under the components. Clearances and the size of pads must correspond to the manufacturing capabilities. The same goes for the DRC rules. It is preferable to have several files with different rule configurations. In conclusion, we must note that, when creating a prototype, a developer must clearly realize what kind of goal they strive to achieve and, on that basis, decide what’s worth sacrificing in order to save, in the end. In such a manner, one can effectively build an electronic device that would function properly, while saving on the process of hardware prototype development.