As a branch of digital fabrication, it is used in producing passive and active electronics, in biomedicine, pharmacology, micro-optics, and stereolithography, and in many other applications. In electronics, it is used in the production of rigid and flexible printed circuits, for printing legends, and for applying solder masks. It's even being used with conductive 'inks' to create lines, pads, and interconnects for short-run-production and prototype electronics.

For working with rigid or flexible substrates, the development system of choice is the printing and deposition system, used to develop production processes and produce sample output for evaluating fluid and substrate properties. Precise motion control of components is necessary to isolate characteristics of print head, fluid, and substrate dependencies.

Imaging Technology International (iTi) designs and builds all three types of development systems, production ink jet systems, and related material handling equipment, and provides integration services.

The main printing and deposition system is the XY Materials Deposition System (XYMDS, see photo), used by industrial users, ink developers, and print head suppliers for developing ink-jet-based production processes and jet-able fluids, and analyzing the interaction between fluids and solid substrates. In XYMDS, a rigid or flexible substrate is scanned under a stationary set of print heads. The system produces samples for studying process speed, order of lay-down, resolution, and fluid-to-fluid and fluid-to-substrate interaction.

In developing an XYMDS, iTi engineers needed to integrate a controller from National Instruments and other motion control functions into a high-level software architecture. They then presented XYMDS as a network device in a production and laboratory environment, using the encoder as a synchronizing data clock for position- and velocity-specific processes and using the stages in a vector trajectory for ink-jet material deposition.

At the heart of the XYMDS is an X-Y stage that provides speeds to 1.0 m/sec, acceleration of 5 G, positional repeatability of ±1.0 µm and positional accuracy of 8 µm over 150 mm and 14 µm over 300 mm. The system uses stacked axes; one version also includes a rotary stage, so driven mass is approximately 25 kg. National Instruments' PCI 7342 two-axis servo-motor controller provides linear interpolation for multi-axis movement; it also features 32 bits of digital I/O capability for high-speed capture and RTSI bus for real-time synchronization.

For XYMDS axis-drives, Mark Einarson, territory manager at Western Technology, local distributor for Parker Daedal, helped choose a pair of Parker Daedal Aries drives.

With a Parker Daedal 406LXR linear-servo-motor table for the X axis and a 404LXR for the Y axis. These are slotless, brushless linear-servo motor/ square-rail bearing-positioners with high strength, extruded aluminum bodies with magnetically retained protective seals. They are powered by one rail of high-energy rare-earth magnets. Load bearing members provide heavy load and moment capacity, dynamic stiffness and precise straightness and flatness of travel. An integral linear encoder provides non-contact positional feedback with selectable resolutions from 0.1-5.0 µm and acts as a synchronizing data clock for position- and velocity-specific processes.

Einarson says the application required positioning accuracy and repeatability, which the 400LXR series provides.

System software runs on a standard PC running in a Microsoft Windows environment. iTi developed the software for the motion control, interfaced that with the nozzle layout geometry of the print heads, and coordinated the two, to put each droplet in the right place at the right time. iTi also provided a user interface to make it convenient for process development, writing most of it in C++, with a few parts in N400LXR series NI LabView.

iTi's 2.0 version of XYMDS uses lighter platens to allow higher speeds and better acceleration. This unit uses a Parker 6K multiaxis motion controller.

A redesigned platen removed some weight to boost speed and eliminate errors caused by vibration or motion; part of the challenge was to provide a mechanical platform stable enough for these stages. Isolating electronics below the granite has reduced the possibility of vibration and prevented unwanted movement. With several hours of running, some systems with X-Y tables actually can vibrate across a room.