It is a mix of conventional rigid PCB with flex added able to make connections between other rigid PCB. The flex part can have 1 or several layers like the flex PCB described above. So, it can be used for static or dynamic bending applications. Even if it is the most expensive solution, its advantages are decreasing the weight, offering the best reliable connection without connectors, and resisting harsh environments like vibration or acceleration.
| Feature | Technical specification for Rigid flex PCBs |
| Number of layers | 4-16 layers |
| Technology highlights | Mixed materials including RF and high speed, standard FR-4, polyimide flex. Adhesiveless or adhesive based polyimide flex constructions, with cover coat or flexible solder mask materials. |
| Bending performance | Based on the specific design, the bend performance can range from a basic 90 °bend to fit to a full dynamic flex with 360° range of motion in the flex tail that will withstand continuous cycles throughout the product life. |
| Bend features | Bend radius controls the flexibility of the flex portion of the board. The thinner the material the lower the bend radius and the more flexible the flex section. |
| Materials | RA copper, HTE copper, FR-4, polyimide, adhesive |
| Copper weights (finished) | ½ ounce, 1 ounce, 2 ounce, 3 ounce |
| Minimum track and gap | 0.075mm / 0.075mm |
| PCB thickness | 0.4mm to 3mm |
| PCB thickness in flex section | 0.05mm to 0.8mm |
| Maxmimum dimensions | 457mm to 610mm |
| Surface finishes available | ENIG, OSP Immersion tin, Immersion silver |
| Minimum mechanical drill | 0.20mm |
| Minimum laser drill | 0.10mm standard, 0.075mm advanced |
Rigid-flex PCBs integrate rigid FR-4 sections and flexible polyimide sections into a single interconnected board. The rigid areas carry components and provide structural strength; the flex areas fold or bend to connect rigid zones in 3D space.
Compared with a design that uses separate rigid boards plus FPC cables or wires, rigid-flex solutions remove connectors and manual interconnect steps, reduce assembly risk, and enable more compact layouts. If your product needs smaller volume, lower weight, or higher interconnect reliability, rigid-flex is often the cleanest architecture.
