New SEMI-FLEX pool: 6-layer Flex to install PCBs

Eurocircuits expands their SEMI-FLEX pool: In addition to 4-layer designs, we now offer 6-layer flex to install PCBs. This smart solution is perfect when your board only needs to bend during assembly to fit into a housing. It enables compact hardware integration without connectors or cables, while still relying on familiar and cost-efficient FR-4 technology.

What does SEMI-FLEX mean?

The term SEMI-FLEX can sometimes be misleading. A more accurate description is flex to install. These PCBs are designed to bend during assembly. For example, when electronics need to be mounted inside a housing.

Unlike conventional rigid-flex boards that rely on polyimide layers, Eurocircuits’ SEMI-FLEX PCBs are made entirely from FR-4, the standard base material for most PCBs. This makes them easier and more economical to produce, while eliminating the need for cables or connectors.

The Benefits

• Lower cost – standard FR-4 instead of expensive polyimide
• Higher reliability – fewer transitions, no impedance mismatch issues
• Simplified workflow – design with familiar FR-4, verify in our Visualizer

The SEMI-FLEX Buildup

Eurocircuits’ SEMI-FLEX technology uses a 100 µm FR-4 central core of the bendable section. On each side, a 35 µm high-ductility copper foil is applied, specially treated to withstand bending without cracking.

The buildup is reinforced with a 510 µm FR-4 core and two layers of no-flow prepreg, resulting in a symmetrical and stable buildup that can be bent in any direction.

Key specifications:

• Layers: 4 or 6 layers in the rigid sections
• Copper thickness: 35 µm in the flex section
• Bending radius: depends on thickness and bend angle; typically, up to 5 bends
• Application: flex-to-install – bent once during assembly, stable in operation

Why choose SEMI-FLEX?

SEMI-FLEX PCBs are the ideal choice when you need to fit electronics into tight spaces without adding design complexity. By bending the PCB only during assembly, you achieve compact 3D integration while avoiding the cost and reliability risks of connectors and cables.

With the new 6-layer option, PCB designers gain more routing flexibility and improved signal integrity, while offering cost efficiency, proven materials, and the security of Eurocircuits’ pooling service.

Check your design today

Explore detailed specifications and design guidelines on our SEMI-FLEX pool page.

Ready to try it out? Upload your layout in the Eurocircuits Visualizer to check manufacturability, calculate costs, and validate your stackup instantly.