Essemtec's New Screen Printing Process Prints Fine Structures With High Cross Sections

OLEDs, organic FETs, organic batteries, plasma displays or fuel cells: All these products require multi-layer high precision printing processes for their manufacturing. Until now these applications have been limited due to the printing processes used that only allowed thin layers. This is now changing. With nano pastes and a new printing process, micro structures also can be produced using screen printing and can be built into multiple layers up to very high layer thickness.



“Screen printing now enters completely new applications,” said Joachim Biegel, product manager at Essemtec. During the last few years he worked with the PV Lab of the EPFL Neuchâtel to develop a process and machine. PV Lab (Photovoltaic and thin film electronics laboratory) researches and develops Heterojunction Solar Cells. Using the new printing process and printing machine, these cells are now more efficient than others by several percentage points. However, the innovation from the solar industry can also bring new wind into the thick film technologies.



50 µm wide structures with 40 µm thickness

Conductor lines with widths from 100 to 150 µm and a height of approx. 12 µm have been state of the art for a long time when using screen and stencil printers. However, Essemtec’s SP900-S can print structures that are only 50 µm in width and 40 µm or more in height. The PV Lab in Neuchâtel uses this machine to produce its Heterojunction Solar Cells. These cells now belong to the best cells in the world and the most promising future technologies.



The efficiency of many products depends on the optimal design of the conductors, as do solar cells. The traces on these cells are called bus bars and fingers. They should be as thin as possible to maximize the active area. The cross section also should be as big as possible to minimize the inner resistance of the cell.



Using the SP900-S, solar cell manufacturers can maximize the height/width ratio of the conducting traces. No other printing machine allow such a high layer thickness to be produced and such high cross sections to be achieved. This is advantageous not only in the solar industry but also in other products that require thin lines with high electrical current capacity.