Special Processes for Flexible PCB

There are many types of PCB boards used in the electronics industry and projects. The PCB board is considered the backbone of any electronic device. It has a conductive layer where components are connected to current flow and circuits. Electrical components are fixed on conductive pads on external layers in a shape designed to get component terminals through soldering. Here we discuss the flexible PCB and its special manufacturing process introduced by PCBWAY. So let’s get started.

Table of Contents

What is Flexible PCB?

Flexible circuits, also known as flexible printed circuit boards, flexi-circuits, and flex print, are used for the interconnection of components.
They typically have a thin polymer coating to preserve circuits and a thin insulating polymer layer with a conductive circuit pattern for component connection.
This process has been used since 1950 for the interconnection of electronic devices.
The use of flexible boards has revolutionized the electrical interconnection process.

Structure of a flexible PCB

The main components of a single-layer flexible PCB board are

Dielectric substrate film: The base material of the PCB board commonly used is polyimide, which has high resistance to traction and temperature.
Electrical conductors: They are made with copper and are shown as traces of circuits.
Protective finish, It is made with an overcoat.
Adhesive material (polyethylene or epoxy resin) is used for the connection of many parts of the board with each other.

Advantages of flexible PCBs

Since these boards are flexible, they can easily bend and flex, making the design and working of them easy.
Flexible circuits are also converted into small or irregularly shaped spaces; this feature is not found in rigid boards.
These boards take up less space and reduce weight on the motherboard..
Optimal use of existing spaces is good for thermal management because it reduces heat dissipation.
As compared to rigid boards, these boards provide reliable and long-lasting operation, especially for applications where the circuits are facing vibration and mechanical stress.
The standard interconnection process based on soldered wires and hand-wired connectors is replaced by flexible boards that have low weight and thickness.
They also have high mechanical resistance, and high-temperature resistance, and can handle EMI.

Disadvantages of flexible PCBs

As compared to rigid boards, FPCs have high one-time starting costs. As flexible boards are made for certain uses, the starting cost related to board and prototype design is higher than that of rigid boards.
If the cost factor is important for the use of FPC, then use it for larger production, not for smaller production.
It is difficult to repair or modify these boards. In this condition, first remove the protective layer that wraps the circuit, operate the intervention, and then restore protection.
Flexible boards are a new technology, and not all PCB suppliers and manufacturers support this feature.
During the assembly process, it needed proper care since it could be damaged if not handled accurately.

New Parameters and Special Processes for Flexible PCBs

PCBWAY is the best PCB service provider in China. They not only provide PCB services but also have PCBA on a single platform.

PCBWAY manufactures flexible boards for customers with great quality and according to their requirements. They use the latest machines and have expert staff to handle any type of board.

Here you can see the details of PCBWay Flex PCB manufacturing capabilities.

Item	Capability
Layer	1-12
Board thickness (without stiffener)	4-40 mil
Tolerance of single layer	±1.0 mil
Tolerance of double‐layer (≤12mil)	± 1.2 mil
Tolerance of multi‐layer (≤12mil)	± 1.2 mil
Tolerance of multi‐layer (12mil‐32mil)	±5%
Tolerance of board thickness (including PI stiffener)	±8%
Min. board size	0.0788” 0.1576” (without bridge) 0.3152” 0.3152” (with bridge)
Max. board size	8.668” * 27.5”
Impedance control tolerance	±5Ω (≤50Ω), ±7% (>50Ω)
Min. coverlay bridge	6 mil
Min. bend radius of single layer	3‐6 times of board thickness
Min. bend radius of double‐layer	7‐10 times of board thickness
Min. bend radius of multi‐layer	10‐15 times of board thickness
Min. mechanical drill hole	4 mil
Inner Layer Trace / Space	2 / 2 mil
Outer Layer Trace / Space	2 / 2 mil
Solder mask color	Green / Black
Surface treatment	HASL, ENIG, ENEPIG, Electrolytic Nickel Gold, Soft gold, Hard gold, Immersion silver and OSP, Immersion tin
Laser accuracy (Routing)	±2 mil
Punching accuracy (Routing)	±2 mil ‐ ±6 mil