Production Resources

What makes it “flex”?

Unlike rigid PCBs (FR-4), flex PCBs use:

• Polyimide film (main material)
• Thin copper layers

This allows the board to bend, twist, and fold without breaking.

Steps in Flex PCB Fabrication

The overall idea is similar to rigid PCB fabrication, but with some key differences:

1. Design

• Circuit designed using tools like Altium Designer or KiCad
• Special care for:
  • Bend areas
  • Stress points

2. Flexible Substrate Preparation

• Base material: Polyimide (flexible plastic)
• Copper foil laminated onto it

3. Photoresist & Imaging

• Same photolithography process as rigid PCB
• Circuit pattern transferred using UV light

4. Etching

• Unwanted copper is removed
• Leaves behind circuit traces

5. Drilling / Laser Cutting

• Holes made for vias or components
• Often uses laser drilling (more precise for thin material)

6. Plating

• Copper plating inside holes (for multilayer connections)

7. Coverlay Application

• Instead of solder mask, flex PCBs use coverlay
• Protects circuits while allowing flexibility

8. Cutting & Shaping

• PCB is cut into final shape
• Designed to fit tight or moving spaces

9. Testing

• Electrical and mechanical testing (important due to bending)

Types of Flex PCBs

• Single-sided flex
• Double-sided flex
• Multilayer flex
• Rigid-Flex (combination of rigid + flexible)

Advantages

• Can bend and fold
• Lightweight and compact
• Ideal for tight spaces (phones, wearables)

Limitations

• More expensive than rigid PCBs
• Complex manufacturing process
• Delicate handling required