Designing a board may be challenging, but even more so getting a product successfully to market. Competition is fierce in any field, and established companies can commit millions to firms that assuage consumers’ interest in features. In the event of competing releases, perhaps there is no more relevant adage than “the early bird gets the worm”: except for drastic performance or price differences, most customers will flock to what’s available when it’s available.
PCB rapid prototyping, therefore, becomes an essential basis for a successful entry into the marketplace. This process is not a simple switch to flip – design teams need to be well aware of how to weave in the best practices relevant at all stages of production.
What Does PCB Rapid Prototyping Look Like in Practice?
For some products, reducing time to market can be the deciding factor between success and failure. To that end, it’s appropriate for all parts of development – engineers, designers, manufacturers, programmers, and others – to act in a way that minimizes turnaround time. “Haste makes waste” is an excellent mindset: the steps outlined should not be employed to race through designs but rather to create consistent and thorough approaches that minimize downtime and time spent within a specific process. Rapid prototyping does not mean simple designs, but it behooves the development team to simplify the design wherever possible. In practice, it may look like some of the following advice:
- Reduce the amount of processing a board has to undergo in the first place. For example, components should be placed on a single side of the board whenever possible to reduce time spent on redundant processes.
- In contrast, designs need not be perfectly optimized: prototyping serves as a proof of concept before scaling up manufacturing. While a large production lot would want to reduce the number of vias wherever possible to reduce cost and processing time, a prototype can route less efficiently (through the scope of manufacturing) to reduce turnaround time.
- The fewer processing steps a board needs to undergo, the better. Although yield and cost prohibitiveness are not exceptionally debilitating with the small number of panels associated with prototyping, simplifying the manufacturing processresults in a quicker turn. Take via design, for instance: blind and buried vias often add significant fabrication work. When designs are flexible enough, it may be worth the extra time in layout to ease downstream production.
There is no hard and fast solution for prototyping as the demands of every board will differ. Still, design teams can implement some general strategies to serve the overall speed of the manufacturing process.
DNI Provides Options and Foresight
Given an ultimatum, most manufacturers would prefer to encounter revisions or correctible production errors during prototyping than mass production. Yet, the time-sensitive requirement for a prototype board complicates this calculus. Rarely will prototyping result in a finalized board – even in instances where layout and production are executed flawlessly, designs evolve. Features once thought extraneous may now be deemed instrumental, and vice versa. Designs need to have some baked-in flexibility that allows for continual development even after the board leaves production. One noteworthy method includes do-not-install (DNI) parts in the schematic. Though it may seem counterintuitive to ask designers and procurement to account for items that do not make it onto the board, there are multiple reasons a schematic may call for DNI:
- DNI allows for modularity as the associated land pattern(s) and routing is laid out as if the part(s) were there. Assemblers need only attach the component(s) to complete the circuit. In essence, it’s a forward-looking expansion that saves tremendous time over a complete board revision.
- In terms of product lines, it is far easier to operate from a single bare board design with overlapping components than multiple bare board designs with overlapping components. More popular models can easily be reconfigured from existing stock without sacrificing future flexibility.
- When calibrating impedance networks, it’s valuable to toggle between different configurations – although modeling provides engineers an accurate target, replicating those values may require some tinkering.
Ultimately, DNI components cannot completely forecast changes a board may encounter before its final revision, but it does offer a degree of latitude in design to respond with greater agility.
Design Documents Play A Valuable Role
For as much time as people spend gazing at them, design documents can be an overlooked source of improvements to reduce turnaround time. As the controlling information is disseminated from the layout designer through CAM and machine operators, steps should be taken to ensure the lack of ambiguity and overall readability. These practices should not extend only to rapid prototyping jobs. They should instead form the basis of any good design documentation. Still, adherence to a mentality of producing high-quality documentation can prevent confusion that can lead to delays in manufacturing:
- When in doubt, call it out: if a feature (especially a less ordinary one) seems particularly open to interpretation, the reasonable solution is to attach a callout that clearly states what the fabricator or assembler needs to do. Board cutouts are a great example — without some signifier, a closed shape within the board perimeters could represent many features.
- Readability and legibility are key. It happens far too often that designers are comfortable with the small fonts or similar keys in a legend because they can blow the image up on a high-DPI screen. Operators may be working off a print of a digital document. A good check: documents in viewers should receive a final review without magnification to determine how easily the most pertinent information jumps off the page.
Your Contract Manufacturer Can Get Your Boards Back Quicker
PCB rapid prototyping requires an approach from the entire development team that embraces modularity, simplicity, and clarity in design. When time-to-market is key, you want a contract manufacturer and partners that are well-versed in all aspects of the design process. Look no further than VSE: we’re a team of engineers eager to build electronics for our customers that exceed expectations. Whether a prototype on a tight schedule or a large production run ready for market, we here at VSE possess the know-how to bring your designs to life with exemplary care.
