Flexible PCB Manufacturing & Design Guide

Flexible printed circuit, also known as flexible PCB, is a lightweight and bendable circuit board designed to connect electronic components in limited or dynamic spaces. Compared with rigid PCBs, flexible circuits can fold, twist, and fit into compact electronic designs, making them essential in modern electronic products. At Flex Plus, we provide complete solutions for flexible PCB fabrication, design, and assembly. This page gives you a full overview of flexible PCB structure, materials, manufacturing process, and key applications.

Flex PCB made by laminating a layer of copper foil (usually 17μm, 35μm, 70μm, etc.) to a substrate by hot pressing or chemical deposition, and then etching and other processes. Therefore, the flex PCB does not have a solid rigid support in structure, but relies on its own flexible material to support the layout of the circuit. Flex Plus is able to manufacture ultra-thin flex PCB with a thickness of only 5μm, providing more options for compact, lightweight, and high-performance applications.

What Is a Flexible PCB?

A flexible PCB is a copper circuit laminated on a flexible base film, typically polyimide (PI) or polyester (PET).

This construction allows the circuit to bend or fold without breaking the copper traces.

Flexible PCBs are commonly used in smartphones, medical devices, automotive electronics, and aerospace systems — where space saving and high reliability are required.

See our product types:

Single-Sided Flex PCB

Double-Sided Flex PCB

Multi-Layer Flex PCB

Rigid-flex PCB

Structure and Materials

A flexible PCB is composed of several main layers:

Base Film (PI or PET) – provides flexibility and insulation.
Copper Foil – forms the conductive circuit.
Adhesive (optional) – used in adhesive-based constructions.
Coverlay Film – protects the copper traces while allowing openings for pads.
Stiffener – adds mechanical strength to connector areas or component zones.
PSA (Pressure Sensitive Adhesive) – used when bonding to other parts.

There are two major constructions:

Adhesive type flexible PCB – uses glue between copper and PI layers, lower cost but less heat resistant.

Adhesiveless type flexible PCB – directly laminated without glue, higher performance for fine-pitch or high-temperature designs.

For more design considerations, check our Flexible PCB Design Solutions.

Flexible PCB Manufacturing Process

The flexible PCB manufacturing process requires precision control at every step to ensure dimensional stability and consistent impedance. The general process includes:

Base Material Cutting
CNC Drilling or Laser Drilling
Pattern Imaging and Etching
Plating (Through-hole / Surface)
Coverlay Lamination and Curing
Stiffener or PSA Attachment
Profiling and Punching
Electrical Testing and Visual Inspection

Each step must maintain cleanliness, accuracy, and temperature control to avoid dimensional shift or copper cracking.

Learn more in our Flex PCB Manufacturing Process.

Types of Flexible PCB

Type	Structure	Common Application
Rigid-Flex PCB	Combines rigid and flexible layers in one board	Foldable devices, avionics, compact control units
Multi-Layer Flex PCB	Three or more copper layers	High-end medical, aerospace, or control systems
Double-Sided Flex PCB	Two copper layers connected by plated holes	Automotive sensors, battery packs
Single-Sided Flex PCB	One copper layer, simple structure	Printers, cameras, LED strips

Each structure provides different electrical and mechanical performance. For complex 3D assemblies, rigid-flex PCBs combine flexible and rigid sections in a single board.

Advantages and Limitations

Advantages:

Ultra-thin and lightweight
High flexibility and bend radius
Reduced wiring space and assembly weight
Excellent thermal dissipation
Suitable for dynamic or movable connections

Limitations:

Higher material and tooling cost
Complex manufacturing and assembly process
Requires strict handling to avoid damage

However, with proper design and supplier experience, flexible PCBs can provide unmatched reliability for compact electronics.

Related Resources

Looking for more about flexible PCB manufacturing and applications? Explore these related topics:

TPU Printed Circuit — Stretchable silver circuits for soft robotics and wearables.

FPCB Assembly — SMT and COB assembly for flexible PCBs.

Solid copper vs hatched copper in flex PCB

7 different surface finish types for flex pcb

How to choose a flex PCB substrate PI, PEN or PET?

Need a custom flexible PCB solution?

Our engineering team can help you select materials, optimize stack-up, and provide one-stop manufacturing.

Contact Flex Plus for your next project.

Stiffener Automation onto FPCB, Flex PCB

Sculptured Flex PCB

Sculptured flex PCB is a special type of flexible circuit where the copper thickness varies across different areas. The copper is etched thinner in the bending sections to improve flexibility, while thicker copper is kept at the connector or soldering areas for strength and easy connection. This design reduces the need for connectors or solder joints, making the circuit more reliable and space-saving. It’s commonly used in automotive, medical, and aerospace products that require high reliability.

To learn more about how these circuits are produced, see this guide on sculptured flex PCBs.

Terminology of Flexible PCB Fabrication

Staggered Etchback / Step Etchback

In the context of Rigid Flex PCB manufacturing, "staggered etchback" or "step etchback" refers to a process used to create controlled depth variations in the copper traces or conductive layers of a Rigid-Flex circuit board.

This process involves selectively etching away portions of the conductive layers to achieve different copper thicknesses at different locations on the board.

The purpose of staggered etchback is to optimize the flexibility and bending characteristics of the Rigid-Flex PCB. By varying the copper thickness, the board can have different degrees of flexibility in different regions, allowing it to bend and conform to the desired shape without compromising the electrical performance or mechanical integrity.

Staggered etchback is an essential technique in the fabrication of Rigid-flex circuit board, as it enables the board to accommodate the varying mechanical requirements and fit into complex geometries, common in applications such as aerospace, medical devices, and other electronics where space and weight constraints are critical.