Few, if any, societies have produced as many scientific, architectural and engineering achievements as the ancient Romans. One of their greatest contributions is the Coliseum, which contained a retractable awning, velarium, to shade spectators. This is a feature that many of our present-day arenas do not possess. However, my favorite survivor from that age is the idiom, “When in Rome, Do as the Romans do.” A useful translation of this philosophical advice is to choose the course of action or solution that best fits the situation.
Applying this advice can greatly benefit your PCB development process. For example, there are differences between prototyping and production that can be leveraged to save you both time and cost for your board’s fabrication and PCB assembly. Making design choices to match the current goals of your board manufacturing level begins with understanding the steps of PCB manufacturing and the range of options that can be altered to match your design objectives. Equipped with this information, you can maximize the efficiency of your low volume production development. Let’s first look at the different PCB manufacturing levels and then define PCB design guidelines to maximize low volume production.
PCB Manufacturing Levels
It is common to define the PCB manufacturing level based on the design objective or quantity of boards produced. Often, only two levels, prototyping and production, are differentiated. These distinctions provide a simplistic overview that classifies all of PCB manufacturing as design and testing or distribution. Actually, we can expand the manufacturing landscape to be more accurately defined by the following levels:
- Proof of concept
Most PCB designs begin at this level of board manufacturing. At this level, it may be unclear whether any further development will actually take place; therefore, only a single board or a very small number will be produced to provide a proof of concept.
Prototypes are produced for designs that have been proven, or at least deemed, to be pursuable. At this level, the objective is to refine the design to achieve optimal performance and remove any potential flaws or errors. Typically, there are multiple cycles of design or redesign and manufacture for PCB prototyping. Board numbers may range from a handful to the low hundreds.
- Low volume production
At low volume production, the design has been tested and finalized. Therefore, the objective is to create boards to use in end-user systems and products. PCBs manufactured at this production level may be highly complex or intended for deployment in specialized systems, such as satellites, medical devices or other critical system equipment. At this stage, board numbers may be in the hundreds.
- High volume production
This level is most often associated with commercial products that are mass-produced and distributed. A major concern here is component and per unit costs, as board numbers may be in the tens to hundreds of thousands or even millions.
All designs may not progress through all of the above levels, but it is common to have a prototyping level followed by a transition to either low volume or high volume production. Although some considerations are applicable to both, there are guidelines that should be included in your PCB design for low volume production.
PCB Design Guidelines for Low Volume Production
Production PCB manufacturing, whether for low volume or high board counts, is quite different from prototyping. During prototyping, it is almost expected that there will be issues requiring redesign before a final or production ready design can be achieved. This view of prototyping is not cynicism. Instead, it is the sober realization that you will likely need several design-manufacture-redesign cycles to perfect your design. Far from being a discouragement, prototyping provides the flexibility to simplify board verification and testing. If utilized properly, this can lower your overall development costs. For example, board material and component selections may be relaxed to expedite the prototyping stage.
Unlike prototyping, flexibility is minimal for high volume and low volume production as the design is finalized. At these levels, there are specific guidelines that you should employ, as listed below:
PCB Design Guidelines
|Prototyping||Low Volume Production||
High Volume Production
|Apply component optimization to guard against component shortages and production delays||NO||YES||YES|
|Select the best PCB materials based on your design’s application||YES||YES||YES|
|Design for device reliability to prevent product failures in the field||YES||YES||YES|
|All aspects of design should be optimized for per-unit cost.||NO||NO||YES|
|Include design for testing (DFT), if warranted, to ensure board performance||NO||YES||YES|
|Ensure that your CM’s manufacturing process includes good quality control (QC) techniques and methods||YES||YES||YES|
All of the guidelines listed above are required for PCB volume production. However, some may be relaxed or omitted to expedite prototyping, as indicated by the ‘NO’ entries, prior to production level manufacturing. For high volume production, it is critical to maintain performance and reliability standards while minimizing component and material costs because a single penny’s difference can translate into substantial additional costs. Low volume production, on the other hand, is more flexible. In some cases, design parameters may be relaxed, especially if it is anticipated that client feedback or field results may necessitate design modifications. In other cases, low volume production may be more rigid and prioritize cost considerations as high volume production does. The best and most efficient way to implement these guidelines is collaborating with your CM to employ design for manufacturing (DFM) principles that incorporate your design intent.
Tempo Automation is the industry leader in fast, high-quality PCB manufacturing for the crucial design-test-redesign prototyping level and low volume production. We will partner with you early in your development process and provide support to assist you in the optimization of your boards’ manufacture.
|Tempo‘s Custom PCB Manufacturing Service
And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on low volume production or how to make design choices to maximize the efficiency of your manufacturing level, contact us.