PCB with depth-milled bending area


In many applications, miniaturisation is a must. With the FR4 Flex Board, SCHWEIZER has a sophisticated solution for realising "3D PCBs" with a bending angle of up to 180°. Thanks to the bending areas, an assembled PCB can be tailored to complicated installation conditions. FR4 Flex does this without special materials such as polyamide and without jumpers, cables, or plugs. A standard PCB is depth-milled in the bending areas and can be structured with a pattern of up to three layers in these areas.


  • All applications with restricted installation options along with high reliability requirements
  • In control devices, the contacting of multi-pin connector plugs is moved into the third dimension with the FR4 Flex PCB


  • Significant cost advantages in comparison with today's flex-rigid circuits with special materials
  • Assembly of depth-milled PCB possible when flat
  • Coverage of conductor lines in bending area of outer layer with flexible solder mask

Special features

The FR4 Flex PCBs are designed for one time bending. However, in order to demonstrate reliability if rework is indeed necessary, ten bends have been performed at the approved bending angles. Bending angles between 0° and 180° can be achieved depending on the lay-up.

Design rules


Here you will find current information about our design rules and our PCB standards.

SCHWEIZER has developed dedicated testing equipment for the qualification of the FR4 Flex technology. Extensive load tests were used to specify the maximum bending angle and the maximum permitted number of bending cycles. The values differ depending on the base material, prepreg type, thickness of the copper cladding, and temperature load profile. Please contact us! We'll find the perfect solution for your 3D challenge.

Schematic layout of an FR4 Flex PCB with three layers in the bending area

Cross section of an FR4 Flex PCB:

Contact info

Rainer Jäckle

Telefon: +49 7422 512-291


Rainer Jäckle