Flexible printed circuit boards

Smartphones and other mobile electronics not only have to be powerful but also very lightweight and small. Printed circuit boards are needed, as always, to connect all sensors, microphones, cameras, speakers and computing units together in a tight space. These modern devices require printed circuit boards in the form of thin films because they are small and lightweight and can also adapt to the shapes in the housing rather than dictating that shape. The components need to be soldered onto the circuit boards. These solder joints need to hold, and the tracks need to adhere to the film, reliably - even in the smallest structures.

The production system needs to coat up to 5 km long and 1600 mm wide film in a roll-to-roll process with copper in a thickness of only 12.5 μm over its entire surface. The galvanic reinforcement and structuring of the copper layer are downstream processes. The system firstly needs to remove any residual water from the film by heating it under vacuum. Then an adhesion coating needs to be applied, which must be free of chromium for environmental reasons. Last comes the over 100 nm thick copper layer. The system needs to be able to be quickly evacuated again after changing the coils in order to lose as little time as possible.