Guidelines for Non-standard PCB Form Factor Design

October 2, 2018 , in Blog

Henry Ford, the great industrialist, not only transformed the quality of life for many of his contemporaries by making automobiles affordable but also raised the bar for industrial efficiency with his assembly line. Dividing assembly into a series of precise sub-tasks performed sequentially enabled him to rapidly produce exact replicas of his vehicle. This concept remains the hallmark of manufacturing to this day. Ford’s process had a single drawback, however: inflexibility. As he it put it, “Any customer can have a car painted any color that he wants so long as it is black.” By refusing to adapt to increased customer demand for non-standard colors, Ford opened the door for competitor growth and undoubtedly drove some of his clients to rival manufacturers.

Round PCB with cutout

The usage of electronics in virtually all modern-day products has increased the demand for changes to the standard rectangular PCB form factor. And lest you be like Ford and close the door to these clients, designing boards with a non-standard form factor must be accommodated. Your PCB design process should incorporate the impact of the form factor on all of the manufacturing steps for your board. By understanding the types of non-standard form factors that you may be called upon to design, you can employ the necessary guidelines to support your contract manufacturer (CM) and minimize any turnaround delays or additional costs.

Types of Non-standard PCB Form Factor

For some electronic devices, the mounting of the board along with its enclosure are post-development concerns. However, if you have a module-based design like Raspberry Pi or must fit your board in a predetermined enclosure or case, the form factor may be non-standard and fixed. Each of these types of PCB form factor creates additional issues for the manufacturing of your boards. Generally, non-standard form factors can be classified according to their shape or flexibility.

  • Shapes – This includes any board that is not rectangular. The most used shapes are:
    • Circular
    • Triangle
    • Other polygons
    • Non-geometric shapes

For non-rectangular shapes, a major concern is ensuring that board edge clearance rules are followed. Violations here may present problems for the depanelization of your boards during assembly.

  • Flexibility – This includes any board that is not classified as rigid.
    • Rigid-flex
    • Flex

Flex boards require a coated overlay different from the solder mask that is applied to rigid boards. Flex boards also have to meet bendability requirements as stipulated by standards including IPC-6013C, which may require specific testing by your CM.

Guidelines for Non-standard PCB Form Factor Design

The need to design boards with a non-standard form factor will become more prevalent as new technologies emerge and the sizes, shapes and functionality of electronic products continue to evolve. Therefore, your design tool bag should include best practices that allow for non-standard PCB form factor design and development meeting the same requirements as for rigid boards and include panelization design capability. By following the guidelines below, you can greatly assist your CM in manufacturing your non-standard PCB form factor boards.

  • Choose the proper materials for your flex or rigid-flex design.
  • Ensure that you follow your CM’s DFM tolerances for board edge clearance.
  • Orient your components according to your CM’s DFM tolerances for spacing and clearances for your non-rectangular board design.
  • Provide good, clear reference indicators and other markings to ensure accurate placement of components.
  • Design and provide your CM with a panelization layout that indicates which areas should be scored and routed to save time and possible redesign.
Tempo‘s Custom PCB Manufacturing Service

  • Accurate quote in less than 1 day.
  • Performs entire turnkey process in as fast as 3 days.
  • Emphasizes DFM to eliminate time-consuming back-and-forth design corrections.
  • Sources components from the most reputable suppliers in the industry to reduce procurement time.
  • Performs multiple automated inspections during assembly to ensure PCB quality for prototyping.
  • Provides support throughout the PCB manufacturing process, beginning with design.
  • Smooth transition from prototyping to production.

Tempo Automation is the leading turnkey prototype PCB manufacturer in the industry and committed to providing you with the highest quality PCBs with the fastest turnaround time. We will partner with you from day 1 of design and work with you to accurately incorporate your design intent.

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 PCB form factor, especially regarding how non-standard boards impact your board fabrication and PCB assembly, contact us.

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