When it comes to cooking and baking, one often hears the delineation: the former is an art, while the latter is a science. If that’s true, consider me a jazz musician in the kitchen – I work from mental fragments of recipes, adjusting the quantity based on what’s on hand and substituting items with impunity. This strategy allows for significant tinkering with cooking time, spices, and ingredients, allowing me to construct a dish as I see fit and as tastes evolve.
The essence of my kitchen approach applies to PCB prototype design. Design and fabrication, using the above comparison, is cooking and baking simultaneously – the process from beginning to end is highly involved with many factors to weigh and processes to incorporate. Similar to choosing a recipe before determining the necessary portions, design teams must build a board that meets all necessary evaluators while minimizing cost.
The Steps to Prototype Production
PCB prototype design is essential in any design as the bridge between concept and finished product. Before entering any large-scale production, design teams will want to ensure that the board is firstly feasible. This process will begin before any layout work for the sake of efficiency. Designers will want to insert themselves between the engineering team’s requests and the realities of the materials and fabricator’s technology. Following a mutual agreement between all parties, the design first sets out with an initial board that meets the basic structure (both figuratively and literally) set out by the engineering team. The layout will want to begin with a feasibility study to determine if the density of the components can operate within the provided dimensions.
Following this, the layout needs to decide upon an initial prototype build that successfully captures the criteria set out by the engineering team. Core functionality such as the board dimensions, via structure or structures, impedance profiles, and the stackup will need to accommodate design expertise and physical limitations, be it the raw materials or machinery. The board’s main features drive the design ruleset and features that need to be most exemplified, such as power performance, signal integrity, RF design, and other major factors that determine operation.
A basic layout checklist might go as follows:
- Collaborate with fabricators to build out design ruleset and stackup.
- Create land patterns and assign them to the schematic.
- Export netlist from schematic to board file.
- Group component placement by function and schematic file association.
- Fan out power/ground pins first, then signals.
- Design power/ground planes.
- Critical routing (clock signals, differential pairs, etc.)
- General routing.
- Documentation design and file output.
In particular, the design rule parameters may be the most invaluable to the initial prototype build. Although there is no reason to encourage poor layout processes, proof-of-concept regarding a physical board is of the utmost importance at the outset to determine the interplay between the design and fabrication. A failure at this stage represents a significant cause for reevaluation of both design and manufacturing processes to ensure the build’s stability.
PCB Prototype Design is Refined Through Revisions
Final approved PCB designs don’t happen overnight. Revisions, beginning with prototyping, is a highly iterative process that, through some bounded trial and error, helps optimize and refine the design. Following a successful prototype build that meets initial requirements, production revision can fork along two paths:
- Design can remain in the realm of pure prototyping. Production quantities remain small, sometimes on the order of 10 or less. There is a reduced emphasis on eliminating redundant features such as total via count that could comprise high cost in scale.
- Prototyping could progress to a board intended for mass production runs. While the exact number may differ, reducing machining processes wherever possible will influence attributes of the economy of scale, primarily total turnaround time and cost.
Regardless of its ultimate destination, a feedback loop among designers, developers, testers, and manufacturing will be the guiding principle behind updates to the design. The best way to approach revisions is to ask what aspect it intends to improve in the design: performance, functionality, or ease of manufacturability. Prototype boards will want to contain significant latitude in the customization of particular circuit characteristics; by allowing testers and engineers to adjust performance on-the-fly, revisions can be kept to a minimum. This step helps maximize the return on money and time spent within fabrication processes.
Your Contract Manufacturer Is Committed to Performance in Production
PCB prototype design serves an essential role in any design as the bridge between concept and finished product. It is highly collaborative and iterative between design team members, and the overarching prototyping process can extend across dozens of revisions. To that end, the quicker the design team can build the initial prototype, the faster the product can pass through revisions and reach end users. A contract manufacturer like VSE can take all of the guesswork out of the design and fabrication of your board. At VSE, we have a simple approach: our team of engineers designs electronics for customers. Coupled with our excellent manufacturing partners, you can rest assured that your design is in the best hands.
