- What is an electrical product design and how does it begin?
- The prototype space of design has one foot in concept and another in practicality.
- The final revision must take into account the economics of mass production.
Electrical product design begins on something simple like perfboard, but quickly builds in complexity.
Product design is a complex field, and electrical product design is no exception. A litany of professionals across a spectrum of fields needs to lend their expertise to design aspects that most people would be unaware of, not to mention the sheer depth of the topics. From initial inception to creation, approval, prototype, and beyond, a team must work in lockstep to ensure a project meets its stated goals and functionality without sacrificing performance.
As an overarching interdisciplinary combination of fields, electrical product design can quickly be bogged down by industry jargon or kept at a high level of abstraction that can also be somewhat confusing to those unfamiliar with the process. Overall, designers must remain cognizant of how different features and parameters affect aspects of board design that can seem completely removed.
How Does Electrical Product Design Begin?
Electrical product design is a vast topic that spans multiple disciplines. For any product, it's paramount to begin with the scope of its function – what it does and how it does it. The genesis of any great product can start with a simple idea by a creative team, feedback shaped by market research, or a further refinement or reimagining of an existing design. One of the greatest challenges in product development is deciding upon a scope – without setting some hard limits as to what a device intends to target, feature inclusion can lead to bloat and an overall unfocused design that can only be resolved with longer lead times or a later jettisoning of features. However, future-proofing designs rely on ensuring that a project is able to adeptly handle current needs as well as reasonably anticipate trends to come. These countervailing inputs drive product design and significant resources are dedicated to hitting the sweet spot.
After some formulation by the design team, a rough build will be mocked up to provide the earliest level of proof-of-concept. Performance is not the goal, but functionality: designers want to provide a tangible item that shows that stated goals and benchmarks are realizable. To achieve this, a simple build is utilized to show only the bare features of the board divorced from most material and signal integrity practices that aim to mitigate the deleterious effects of poor interconnect technology. A perfboard or stripboard design will be highly unoptimized in a number of facets, with component selection being the most readily obvious drawback, due to through-hole being the only acceptable technology for this stage of design (not including breakout boards).
Cost analysis will be another important stage of pre-planning. Especially in larger companies, this will arguably be the most important stage prior to design, functioning as a determining factor in the economic feasibility of the product. A successful product launch and life cycle will look considerably different depending on the targeted market, class of electronic, and service life. Marketing and analysis can help determine the price point, the size of the initial production run, and other critical financial components that will shape the goals of product launch and lifetime success.
Procurement will be necessary for any level of production, but exceptionally so in the case of boards ticketed for large production runs. With current chip supplies on massive backorder as the semiconductor industry moves to address shortages due to the global supply chain disruption of the past couple of years, it is more important than ever that component selection is provided early enough to teams to meet limited supply quantities. There is always some wiggle room, as teams need to bake in a minimum level of flexibility in procurement due to some extensive delays, but the earlier a list is submitted, the quicker the design team can build land patterns and prepare the design.
The Role of Prototyping in Development
A design is now ready to enter its second major phase: prototyping. The importance of prototyping cannot be overstated, as its flexibility and cost convenience allow the design teams a reasonable pivot point without sacrificing development time. The prototype serves to rubber stamp the design (by confirming the logic) as well as the manufacturing work (by confirming device functionality). Importantly, it serves as a proof-of-concept, bringing drawings and simulations to a tangible product that can provide instantaneous feedback.
Design flexibility is key at this point, from the schematic all the way through the manufactured board. With the complexities and intricacies of PCB design, it’s nearly universal that boards will require additional revisions. The design team’s approach should be to minimize the number of revisions while still allowing for ample experimentation in the build.
Although the time spent in manufacturing is likely a fraction compared to the time spent on development and testing, manufacturing processes are far more liable to bottlenecking, especially for out–of-house productions. While prototyping needs to winnow down a build that takes in mind design-for-manufacture, there is significant leniency in how designers and fabricators can approach this. To that end, here is a list of some common design tenets that can be employed during the prototyping stage of design:
- Simplicity over-optimization - Low production quantities mean unoptimized boards can focus on the task at hand: building a reasonable approximation of the final design in a short timeframe. A relaxation of overall fabrication time and labor means designers can take a less exacting approach (within specifications and reason) to interconnects and other PCB features that would otherwise favor manufacturability.
- Decision fluidity - It’s unlikely that a board would change significantly between the prototype and final product – there is not enough technical knowledge to be gleaned by altering features, materials, or structure to the point where the two design stages differ significantly. However, it may come in the course of development that the prototype stage serves as a low-risk environment to tinker significantly with designs, provided that these changes do not upset any other parameters or specifications. In a more general sense, this allows design elements of the board to optimize over time, allotting a range of acceptable options that reduce overall turnaround time.
- Future expandability - Designs by nature need to expand, contract, fit new functions, and excise unnecessary ones; very rarely does the final product perfectly represent its initial prototype with a healthy dose of optimization design. A few small design choices–such as switching to smaller packages to accommodate a repetition of a circuit or allowing testers to swap out impedance factors to fine-tune parameters without the need for small and hard-to-solder SMT parts–can make a difference.
While all levels of prototyping must keep design-for-manufacture practices in mind, there is still a wide latitude as to how a build may be approached. An initial prototype revision may be nothing more than a relatively simple turn job in order to test material parameters combined with a generalized layout. Software compatibility with on-board hardware will represent an important point of testing, and developers will want to implement their code at the earliest opportunity to optimize alongside physical characteristics (e.g., skew, rise/fall times, etc.). There may also be a matter of stress testing for strenuous field deployments. Whatever that may entail, the earlier a testing group can begin work on a fabricated product, the earlier important operating specifications and response to external factors (such as heat and humidity) can be assuaged for field condition operation.
A board is only as good as the sum of its processes – it’s a good idea to test these before ramping up production!
Finalizing Designs for Mass Production
If prototyping serves as the proof of concept, mass production is the set revision to prepare for the market. While there is much room for tinkering during prototyping and revisions, the design at this point should be set in stone, minus any small optimizations that will enhance performance or reduce cost. Small changes, say minimizing the through-hole count, can yield substantial savings over large production lots. The design must balance producibility and yield against best performance, which can clash at times. Designers will want to make sure that rigorous fabrication processes or specialty materials are truly required by the design, lest the cost of their inclusion be multiplied several times over.
Beyond tidying up the design and tying any loose ends, there are a handful of optimization tweaks to incorporate that ensure the design is produced to maximize space and performance. Some of those are listed below:
- Design for manufacturability - Transitioning from the prototype stage of development to the final product involves analyzing the design for any inefficiency when it comes to fabrication and assembly. Even moderate production lots are likely to see significant cost reductions and performance increases when the design is viewed in this light. In effect, a DfM board is not only an optimization of the design but an optimization of what machinery and technology are available for the various manufacturing processes.
- Design for testing - Testing and quality assurance can come in many forms, but it is imperative that a board’s test functionality is both easily accessible via edge connector and test point placement on the top and bottom sides. Depending on the exact cutoff of production, certain testing methods will be far better suited for high volume throughput than others, with a bed-of-nails test fixture over a flying probe system an obvious example. While the bed-of-nails is much slower than a flying probe machine when production quantities are low due to the design and fabrication time of a fixture, the test itself is far more expeditious, making designing to the former test method more beneficial in reducing turn times during quality control.
A high-level, general flowchart of electrical product design.
Electrical product design invokes a large host of topics, acting as the fruition of multiple professional fields. While design in an abstract sense may be complex, PCB design tools can simplify the process. With OrCAD PCB designer, it’s easy to integrate design workflows from the schematic level and up to design boards that excel in performance while meeting all necessary engineering requirements. The intuitive user interface and powerful toolset grant designers a wealth of options to approach PCB layout design. For additional functionality, users can explor Cadence’s PCB design and analysis software for even greater levels of simulation, diagnosis, modeling, and more.