Technical Papers

A System Solution for High-precision Direct Imaging of PCBs

Drive Technology Including Control System and Imaging Heads

Modern digital direct imagers based on LED (light emitting diodes) technology enable to project the strip conductors by means of UV LEDs onto the board material. The faster and more precise the direct imaging of the machines, the better the production process. This objective can be reached by an optimal synchronization between control system, drive system and the direct imaging unit. This is why Schmoll Maschinen GmbH chose the complete solution by SIEB & MEYER and VISITECH. The system solution consisting of a drive system and imaging heads provides the direct imagers of series MDI with a reliable and highly precise control system for complex exposure processes.

For more than sixty years Schmoll Maschinen GmbH has manufactured production machines for electronic mass production and micro processing applications. The portfolio covers all relevant process steps for mechanical and optical micro machining. "Customers in the PCB industry and related markets appreciate our comprehensive experience in highly demanding technology areas. The main focus during development is on functionality, precision and reliability," Dennis Pusch, project manager and technical sales representative DI at Schmoll Maschinen GmbH, explains. The product range in the optical system applications also covers direct imagers - which were based on laser technology with one wavelength to start with. Then, a few years ago Schmoll Maschinen switched to the LED-based technology with multiple wavelengths.

A Complete Solution with Imaging Heads and Drive System

In cooperation with VISITECH, a Norwegian specialist, Schmoll decided to equip its direct imaging machine with imaging heads based on UV LED technology. In 2014, the two companies started the development of this new machine. Included was also the drive technology by the Lueneburg-based company SIEB & MEYER. "VISITECH recommended the drive technology. Both partners had already implemented several projects in the field of direct imaging and hence could guarantee perfectly synchronized systems," Dennis Pusch remembers. "We also had good experiences with SIEB & MEYER in the past – primarily in the area of CNC applications."

A precise and quick axis control is extremely important for direct imagers. The series MDI has an X-axis with imaging heads and a Y-axis with a movable machine table. The work piece is placed on the table and exposed to the direct imager in a stripe motion. The specialists call it "stitching" because the stripes are placed side by side. "Needless to say that gaps, axial offsets or overlaps must not occur in such an exposure process," Dennis Pusch points out. "Of course, this means that the control must be highly precise." However, not only precision, but also speed is one of the requirements, since the customer wants to achieve a good throughput with its machines.

Synchronized Technologies for the Best Machine Performance

The mentioned requirements can be fully met by the technology provided by SIEB & MEYER and VISITECH. By now the partners offer their products as a system solution, as the combined technologies have proved themselves well in different applications. The system consists of the LUXBEAM Lithography System LLS with UV imaging heads by VISITECH combined with the motion controller MC2 and the servo amplifier SD2S by SIEB & MEYER. VISITECH realized the LUXBEAM Lithography System LLS with UV imaging heads based on the DLP™ technology (Digital Light Processing), high-precision optics, a powerful UV light source and the corresponding image processing software.

The system communicates via Ethernet with the motion controller MC2. The system by SIEB & MEYER provides a nanometer accurate position signal required for synchronizing the exposure process to the relative movement of the axes. Non-linearities or mechanical tolerances of the real machine can be compensated with the help of the motion controller MC2 and the servo amplifiers SD2S. "The result is a perfectly aligned system solution which ensures an optimal machine performance," Norbert Bajon, sales representative at SIEB & MEYER AG, says. "Moreover, the users benefit from a reduction of the development time and the time to market (TTM) when launching the machine – after all we have already done the work regarding the core system."

With the motion controller MC2 and the associated servo amplifiers SD2S SIEB & MEYER provides a powerful system for high-precision and dynamic movements. Fields of application are not only the direct imagers for PCBs, but also machines for ultrasonic and optical scanners, printers and X-ray processes. "The quality of the machining process for all these applications depends on the precise synchronization of the processing head to the axes movements," Norbert Bajon explains. In case of Schmoll's direct imaging machines the technology by SIEB & MEYER has proven perfectly effective. The machines work as fast and precise as the manufacturer and the customer imagined. And if an error should occur, it can be easily identified and corrected. "The solution by SIEB & MEYER enables to read out errors which is of big help for the service technicians," Dennis Pusch concludes.


More information about: Schmoll MDI Direct Imaging Machine

The series MDI convinces by its extremely compact design and flexibility in oder to process a vast range of resist and ink types, both Standard and LDI versions. Based on the field-proven light engine with over 2 million individually addressable micromirrors and powerful UV LEDs the MDI achieves best quality and optimized cycle times. With the combination of a multiple wavelength system and precise registration accuracy the MDI offers a powerful system for direct imaging and covers a wide production scope starting from prototyping up to series production.


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