Flex to Install Bare Board or Assembled PCB’s
Made in Europe
Eurocircuits’ PCB SEMI-FLEX pool is a solution for flex to install PCB’s, typically 4 layers, made entirely of FR4.
Unlike conventional flex-rigid PCB’s, the flexing element is not polyamide but a thin FR4 core with two layers of copper specially treated to flex without cracking.
- Bare Board or Assembled PCB’s
- Bare Board PCB’s in 7 Working Days* or Assembled PCB’s in 12 Working Days*
- See Tables Below for Available Specifications
- No Tooling Charges
- No Minimum Order Charge.
- 100% Manufacturability Check Prior to Production
- PCB Configurator to check and upload design parameters before pricing
- PCB Checker to analyses your data before you place your order
- BOM and CPL analysis
What is SEMI-FLEX
SEMI-FLEX is a flex to install PCB, typically 4 layers, made entirely of FR4. Unlike conventional flex-rigid PCB’s, the flexing element is not polyamide but a thin FR4 core with two layers of copper specially treated to flex without cracking.
Why use SEMI-FLEX
SEMI-FLEX is flex to install. Unlike polyamide, the FR4 core is not capable of continuous flexing.
However it will bend a limited number of times (typically 5 – see the technical specification below) at a controlled radius and to any angle.
This makes it an ideal solution where you need to mount two PCB’s in a unit at an angle to each other. Instead of using connectors and cables or a composite flex-rigid PCB, you can design a single FR4 SEMI-FLEX PCB which can be safely bent a sufficient number of times to allow installation and subsequent maintenance as needed
Eurocircuits’ SEMI-FLEX pool
Eurocircuits’ 4-layer SEMI-FLEX PCB’s use a 100 micron central core for the flex area, with 35 micron high-ductility copper foil on each side.
The stack is then made up on each side with a 510 micron FR4 core and two layers of no-flow prepreg (see the full technical specification below).
An alternative technology is to build a 2- or 4-layer PCB and then depth-mill the material away to leave a thin section as the flex area.
We have adopted the core solution even though it needs more operations and so is a little more expensive. It gives a symmetrical build and so a more stable board, while depth-milling is difficult to control meaning that the flex area may have an irregular thickness.
With a core-build we through-mill (rout) the prepreg before pressing. We can then rout the outer layers with any minor variation in cutter depth being absorbed by the void.
|SEMI-FLEX pool Service Parameters|
Minimum Bend Radius
Maximum Bend Angle
Maximum Number of Bends
SEMI-FLEX length Calculator
(2 x pi x bend radius) x (bend angle/360)
For example, bending 5 times over an angle of 180 degree with a radius of 5mm requires a minimum length of the semi-flex part of 15,7mm
Copper thickness on SEMI-FLEX Core
35µm high ductility copper
Highest Pattern Class
Class 6 – 150µm track/gap (to accommodate the bending)
Slots and cut-outs
Corners in SEMI-FLEX Area Profile
Minimum radius 1.00mm
Corner where a Narrow SEMI-FLEX Area Joins Rigid Area
Minimum radius 1.00mm
Use copper on both sides
Use copper pour around tracks where possible
Yes – At each end of the Semi-Flex Material
Width of Semi-Flex Material or 5mm x 5mm whichever is the greater
Material (rigid and semi-flex cores)
Number of Copper Layers
1.55mm (see build map)
SEMI-FLEX Core Thickness
Outer Layer Start Copper Foil
Min. Track Width/Spacing
Min. Finished Hole Size
Pooling – ENIG, IM Ag
Break-routing or V-cut
Slots and Cut-outs (milling)
Tool sizes – 0.5, 1.2, & 2.0mm – in Rigid Area Only
Advanced Technologies Allowed
Pooling – Peelable mask, PTH on board edge, Round edge plating, Copper up to board edge, Heatsink paste, Via filling, Edge Connector Gold
Non-Pooling – Carbon pads
Advanced Technologies Not Allowed
Blind & Buried vias
Not yet available
Preferably delivered in a panel for safe handling
|SEMI-FLEX pool Assembly Service Parameters|
Number of Component Layers
1 or 2
1 PCB and up
12 working days* (7 for manufacture and 5 for assembly)
Minimum PCB Dimensions
Width of Semi-Flex Material or 5mm x 5mm – whichever is the greater
Maximum Customer Panel
326mm x 426mm
SMT – single or double sided
THT – single or double sided
SMT + THT Mixed Technology – single or double sided
Passive Components – 0201 and higher
Active Components – from 0,35mm pitch
BGA – 0,4mm pitch and above
Basis SAC 305 Sn 96,5 Ag3 Cu 0,5 lead-free
Solder Paste Stencil
(included in the assembly cost – not delivered with the assembled boards)
All Components Sourced by Eurocircuits
(Components not sourceable by Eurocircuits can be supplied by the customer)
Solder Paste Inspection (SPI)
- Subject to design meeting our SEMI-FLEX pool manufacturing and assembly specification and component availability.
- The price cannot be automatically calculated for a PCB containing more than 200 BOM lines or 1000 component placements, our engineering department will evaluate and send you an offer usually within 24 hours.
- These conditions are available in our calculator/Visualizer and will only be confirmed in our order confirmation.