In view of the increasing demand for increasingly complex electronic components with an increasing integration of more and more functions on chips and other electronic components, the requirements in terms of complexity and miniaturization of conductor tracks, pads and other structures on the circuit board are also growing. For conductor track widths and spacings of less than 50my, the contact exposure technology using exposure masks, which is widespread in the circuit board industry, reaches its limits. Direct imaging by laser (LDI), in which a laser guided by a complex mirror system projects the layout images onto the photosensitive layer of the circuit board, was for a while the only and extremely maintenance-intensive technology to meet these miniaturization requirements. PRECOPLAT is now relying on a more cost-effective and resource-saving direct imaging technology based on ultraviolet LED light, the so-called micromirror digital imaging, developed by the German drilling machine and exposure technology specialist Schmoll Maschinen.
The fully automatic MDI system from Schmoll is characterized by the fact that highly concentrated UV light with a defined wavelength is directed over a microchip equipped with thousands of high-precision micromirrors and the layout is created on the circuit board in a short path with less energy loss than with a laser. Due to the shorter light path and the lower power loss, only LEDs are required as a light source and the interference-prone lasers with a much lower durability can be dispensed with. Thanks to multiple wavelengths, the system can also guarantee a suitable light spectrum for the photosensitive solder mask production. Since the exposure heads can be flexibly aligned in all directions with the mirror systems, it is possible to serve a wide variety of panel formats with little effort and without additional set-up time. As usual, the established use of linear drives and direct position measuring systems ensures reproducible results of the highest precision.
Compared to conventional LDI systems (laser direct imaging), the MDI machines also require significantly less space and have a significantly better overall energy balance. Since the LEDs require less energy to generate the necessary exposure energy, the energy requirements for machine and room cooling are also lower.
The MDI-TTG (Tandem Table) from Schmoll Maschinen used by PRECOPLAT achieves a theoretical resolution of 15my, but finds its practical limitation in the maximum physical performance of the subsequent wet chemical processes such as etching and electroplating at currently 50my. The first fully automatic devices were commissioned in 2022. The systems offer PRECOPLAT customers maximum flexibility for all areas of application, from prototypes to series production.
