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Types of Flex Circuits

Flex and rigid-flex circuits are available in a variety of configurations to meet a broad range of application requirements. Below you will find information regarding the different types of flexible circuits available from a single- or double-sided design to multi-layer technologies, including rigid-flex circuit design specifications.

See our technical article for more information on flex circuit material and construction methods or see our past flex circuit technical webinar to better help you design your next flexible PCB.

Single-Layer Flex Circuit

  • IPC 6013 - Type 1
  • Description:
    • One conductive copper layer bonded between two insulating polyimide layers
    • Example construction: coverlay/copper/flex core
  • Configurations:
    • Single-sided access, dual-sided access, unsupported fingers
  • Flex Core Materials:
    • Standard thickness: 1/2 mil to 3 mil in either adhesive or adhesiveless constructions
    • Standard copper thicknesses: 1/3 oz to 2 oz in rolled annealed or electro deposited formats
  • Coverlays:
    • Standard thickness: 1/2 mil to 2 mil polyimide, with 1/2 mil to 2 mil epoxy or acrylic adhesive
  • Stiffeners:
    • Component support or ZIF connector thickness requirements
    • Materials: polyimide, FR4, stainless steel, aluminum
  • PSA (pressure sensitive adhesives) available for attachment purposes
  • EMI/RF shielding films available
  • Applications:
    • Suitable for either bend to fit or dynamic flex applications
Single-Layer Flex Circuit

Double-Sided Flex Circuit

  • IPC 6013 - Type 2
  • Description:
    • Two conductive copper layers with an insulating polyimide between and external polyimide insulating layers
    • Plated through-holes provide circuit connection between layers
    • Example construction: coverlay/copper/flex core/copper/coverlay
  • Configurations:
    • Single-sided access, two-sided access, castellated holes
  • Flex Core Materials:
    • Standard thickness: 1/2 mil to 4 mil in either adhesive or adhesiveless construction
    • Standard copper thicknesses: 1/3 oz to 2 oz in rolled annealed or electro deposited formats
  • Coverlays:
    • Standard thickness: 1/2 mil to 2 mil polyimide with 1/2 mil to 2 mil epoxy or acrylic adhesive
  • Stiffeners:
    • Component support or ZIF connector thickness requirements
    • Materials: polyimide, FR4, stainless steel, aluminum
  • PSA (pressure sensitive adhesives) available for attachment purposes
  • EMI/RF shielding films available
  • Applications:
    • Bend to fit and dynamic flex applications (construction dependent)
    • High-speed controlled impedance in surface micro strip configuration
Double-Sided Flex Circuit

Multi-Layer Flex Circuit

  • IPC 6013 - Type 3
  • Description:
    • Three or more flexible conductive layers with flexible insulating layers between each one and external polyimide insulating layers
    • Plated through-holes provide circuit connection between layers
    • Example construction: coverlay/copper/flex core/copper/adhesive/flex core/copper/coverlay
  • Configurations:
    • Single-sided access, two-sided access, castellated holes
  • Flex Core Materials:
    • Standard thickness: 1/2 mil to 4 mil in either adhesive or adhesiveless construction
    • Standard copper thicknesses: 1/3 oz to 2 oz in rolled annealed or electro deposited formats
  • Coverlays:
    • Standard thickness: 1/2 mil to 2 mil polyimide with 1/2 mil to 2 mil epoxy or acrylic adhesive
  • Stiffeners:
    • Component support or ZIF connector thickness requirements
    • Materials: polyimide, FR4, stainless steel, aluminum
  • PSA (pressure sensitive adhesives) available for attachment purposes
  • EMI/RF shielding films available
  • Applications:
    • Bend to fit only
    • High-speed controlled impedance in surface micro strip or stripline configurations
Multi-Layer Flex Circuit

Rigid-Flex Circuit

  • IPC 6013 - Type 4
  • Description:
    • Two or more conductive copper layers with either flexible or rigid insulation material as insulators between each layer
    • Plated through-holes extend through both rigid and flexible layers
    • Coverlay selectively applied to flex layers in flexible areas only
    • Blind and buried vias available
    • Example construction: Soldermask/copper/FR4/copper/flex core/copper/FR4/copper/soldermask
  • Configurations:
    • 1 or more flexible layers; multiple flex layers in either bonded or air gap configuration
    • 1 or more rigid layers
  • Flex Core Materials:
    • Standard thickness: 1/2 mil to 4 mil in either adhesive or adhesiveless constructions
    • Standard copper thickness: 1/3 oz to 2 oz in rolled annealed or electro deposited formats
  • Coverlays:
    • Standard thickness: 1/2 mil to 2 mil polyimide, with 1/2 mil to 2 mil epoxy or acrylic adhesive
  • Stiffeners:
    • Component support or ZIF connector thickness requirements
    • Materials: polyimide, FR4, stainless steel, aluminum
  • Rigid Materials:
    • 180 TG FR4, low flow prepreg
  • EMI/RF shielding films available
  • Applications:
    • Suitable for either bend to fit or dynamic flex applications (1-2 flex layers only)
    • High-speed controlled impedance in surface micro strip or stripline configurations
Rigid-Flex Circuit

The Perfect Fit for Your Application

From single-layer to multi-layer flex circuits, we've got configurations to meet your most complex design needs. Whether you're engineering next-generation medical devices, aerospace avionics, military communications equipment, automotive control systems, or consumer electronics, Epec delivers precision, durability, and performance in every flex or rigid-flex PCB we build.

Our experience supporting applications across industrial automation, IoT, and wearable technologies ensures that your design will be ready to meet both performance and regulatory standards. Act now for precise, reliable, and cost-effective solutions for your next PCB design!

Explore more, Common Flex and Rigid-Flex Printed Circuit Board Material Stack-Up.

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