When to Use Flex Circuit vs. Rigid Circuit Boards

Flex circuits offer versatility and other advantages compared to rigid circuit boards; however, the benefits may not outweigh the cost for OEMs with a strict budget or desire to push a reasonably-priced product to market.

Flexible circuits are ideal for medical devices, implants, sensors, and mobile consumer electronics because they fit where space and/or weight is limited. Flexible circuitry is the preferred and recommended solution for products that require:

  • Wiring solutions that fit where rigid boards cannot
  • Thin, lightweight products that are durable
  • Miniaturized versions of existing technologies
  • Three-dimensional packaging geometry
  • A low number of device interconnects
  • Shock and vibration resistance

Flex-circuits support the reduction of an application’s size and weight; and are ideal for high temperature and high-density applications.

High Temperature and High-Density Applications

Flex circuits are preferred by engineers for industrial and manufacturing applications because they are small and durable, capable of withstanding exposure to high heat and resistant to chemicals, radiation and UV exposure. Flex circuits are typically made of polyimide or a similar polymer, that dissipates heat better than the materials used to compose rigid circuit boards. The polyimide or polymer variation allows the flex-circuit to be placed in products that encounter extreme conditions without a negative impact on the product’s performance. For example, industrial sensor technologies.

Will Flex Circuits replace rigid circuit boards for all applications?

No, while flexible circuit boards are useful and grant an array of application uses, they will not replace rigid circuit boards.

The costs associated with the efficiency of implementing an exclusively flexible circuit board design in a consumer product can be high for the manufacturer, trickling down to the consumer. Rigid circuit boards are less expensive to manufacture and install (when using a standard automated high-volume fabricating facility).

A majority of innovative products incorporate flexible circuitry when necessary, and employ solid, reliable rigid circuit boards where possible to keep manufacturing and assembly costs down.

Some manufacturers, like Green Circuits use hybrid rigid-flex printed circuit boards, rigid circuit boards connected to one other using ribbon-like flexible circuits, for product manufacturers. Rigid-flex boards can be compounded and designed to meet any number of engineering needs by focusing on the respective strengths of each circuit board base technology. These boards are commonly used in the manufacturing medical devices and other high reliability products.

We strongly advise that you consult with your PCB and PCBA service provider before starting your project to ensure you are effectively utilizing your provider’s capabilities.


Frequently Asked Questions

What Type of Data Do I Need to Provide for PCB Design (PCB Layout)?

  • Netlist (in the software format desired)
  • Component data sheets (especially for critical parts)
  • PCB Mechanical requirement
  • Schematic with reference designators
  • Keep out area(s)
  • Special routing rules (Impedance control, High speed signals, etc.)
  • PCB stack-up with layer definition

What Type of Data Do I Need to Provide for PCB Manufacturing?

  • Gerber Data (274X format) or ODB++ Files
  • Solder Paste file (in array format if boards are panelized)
  • Fabrication Drawing
  • XY Data
  • Bill of Materials (BOM)
  • Assembly Drawing
  • Mechanical Drawings (If required)
  • Test Procedure (If required)
  • Letters of Authorization for any parts for which you control pricing (if applicable)

What is the Most Common Delay in the PCB Manufacturing Process?

Missing customer-provided data. The BOM with missing reference designators and Assembly Drawings with missing polarity are the most common documents missing in submission with delays often attributing to missing polarity for parts.