The world is a large place. There are so many places to explore and so many wonders to see. Of course, I may never be able to experience everything I would like to, but I still travel every chance I get. Whenever I visit a new city or town, I find myself confronted with the same choice: follow the crowd and explore all of the touristic sights or discover something different. Sometimes when designing PCBs, we are confronted with a similar choice: use a module-based design where much of the work is already done or create a custom one. As with most design choices, manufacturing time and cost tradeoffs need to be considered. By analyzing how custom PCB manufacturing and the module-based alternative affect the product development cycle, we can better decide which path to pursue.
Custom PCB Design and Development
Most electronic circuit development involves designing and developing a custom PCB. This is due to the unavailability of a module-based design that meets the functionality, capability, integration needs or size and shape requirements for the planned deployment. Moreover, if the circuit or system is a part of an invention and needs to be patented, it must be custom-made. Design and development can take substantial time, as the PCB is designed from scratch, with all components freshly selected and sourced and the board individually tested to verify operation and performance. However, after the board prototype has been vetted, the transition to production can quick and easy. Custom PCB design and development offers the following attributes:
- Component selection can be optimized
- Unit cost can be minimized
- Maximum control over changes
- Performance tailored to the application
- Specific look and feel can be created for the PCB
The above attributes starkly contrast with the module-based PCB design and development process, as discussed below.
Module-Based PCB Design and Development
Module-based PCB designs are only available for limited types of electronic circuits. Some notable designs are Arduino, Raspberry Pi, Electric Imp’s imp modules, SiFive’s HiFive and BeagleBoard. These boards all include processors, multiple I/O ports, signal processing circuitry and on-board storage. Although modules are intended to be generic, they do have fixed layouts and components. Utilizing them typically involves connecting the right inputs and outputs to the rest of the system, as well as programming the embedded controllers. There is a wide range of adaptations for specific implementations that include additional integrated components, such as displays and WiFi or Bluetooth modules. Module-based PCB designs greatly reduce the time required to design the board and lend themselves to modular design, where multiple specific function boards are interconnected to form a complete electronic product. This may present some size problems as you have to build your system around the dimensions of the module. The design and development cycle using module-based PCBs have the following attributes:
- Minimal design and prototype testing time
- No control over component obsolescence
- A wide range of choices for configuration
- Most likely offer more capability than needed
Obviously, the use of a module-based PCB design has the advantage of reducing prototyping time, while limiting your ability to make changes, if they become necessary. Before deciding between a custom or module-based PCB design, however, we need to examine the implications for the manufacturing process.
Custom PCB Manufacturing or Module-Based PCB Manufacturing?
The process that completes the design and development cycle is the manufacturing of the PCB. Therefore, the impact of PCB manufacturing must be taken into consideration when deciding whether to use a module-based design or create a custom PCB. This manufacturing choice can best be quantified through the time and cost tradeoffs between the two options. For example, module-based designs usually have low initial non-recurring engineering (NRE) costs. These are one-time costs for the research, design, development and testing of the PCB or product, which—aside from the add-on components—have already been completed for module-based boards. For custom boards, initial NRE costs are always required. The time and costs directly relate to the number of manufacturing cycles required to correct any errors or achieve the desired performance.
Understanding PCBA Complexity: Designing for Trouble Free Manufacturing
This situation may be reversed once prototyping is completed and manufacturing moves to production. For custom PCBs, this transition is straightforward and final NRE costs should be minimal. For module-based PCBs, however, a number of issues may arise during the transition. A major problem occurs if the form factor has to be modified, as this requires a new design. In this case, new boards have to be manufactured and tested, which prolongs the process and raises overall cost. Another potential issue is the need to replace components due to obsolescence, as module-based designs aren’t necessarily designed with the lifetime of components as a priority. Either of these issues can substantially increase the time and cost to manufacture the PCBs. These tradeoffs are compared and summarized for module-based versus custom PCB design in the table below:
|Manufacturing Time and Costs||Module-based PCB Design||Custom PCB Design|
Initial NRE Costs
(Lower for module-based
Higher for Custom)
|The fact that the PCB design is established and will not require many, if any, modifications to meet DFM requirements of the contract manufacturer (CM).||New designs typically require adjustments to meet the DFM requirements of the CM. Depending upon the extent of the changes needed, this can add days or weeks to the manufacturing process.|
(Faster for Module-Based
Slower for Custom)
|Typically, prototyping can be done quickly, as minimal vetting is required.||Typically, prototyping will require multiple cycles to completely vet the board’s operation and performance.|
Final NRE Costs
(Higher for Module-Based
Lower for Custom)
|Module-based designs have inherent waste, such as extra components and higher BOM cost, larger form factor and material cost and potentially lower performance.||Transition to higher volume or production runs should require no changes.|
Occasionally, the design requirements for your PCB may provide the option to use a module-based PCB design instead of creating a design from scratch. While this may initially seem attractive and cost-effective, you should consider the entire design and development cycle before choosing an option.
Based on the significant time and cost tradeoffs involved, you may opt for a custom PCB design instead. It's much like the decision you face when visiting a new city on your worldwide adventures: sometimes it’s better to create your own custom path than follow the crowd.
At Tempo Automation, we specialize in minimizing the turnaround time that can sometimes accompany custom PCB manufacturing. Our fast, precise and transparent turnkey process enables us to collaborate with you to move your design and development forward at your pace. We work with you to ensure that DFM requirements are met and eliminate the need for time-consuming back and forth to build your boards. We also employ a patented BOM verification tool to minimize unforeseen NRE costs that typically accompany module-based design transitions to higher volume production.
|Tempo‘s Custom PCB Manufacturing Service
For your custom PCB design, we will employ our custom PCB manufacturing process to ensure you receive high-quality boards that are built quickly and precisely. As part of our comprehensive service, we will furnish you with the necessary 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 the tradeoffs between module-based and custom PCB manufacturing, or have other questions about your design, contact us.