Direct-drive positioning stages combine high-throughput production with outstanding precision to meet the rigorous demands of semiconductor inspection systems and laser machining
Aerotech's WaferMax direct-drive positioning stages, available in vertical (Z) and rotary (theta) versions, combine high-throughput production performance with outstanding precision in a compact and low-height design to meet the rigorous demands of rotary alignment and focus related applications, such as semiconductor inspection systems and laser machining.
The WaferMax-Z vertical lift motorised positioning stage has a 5mm travel range with a certified straightness/flatness accuracy of +/-2um.
The WaferMax-T rotary stage has full 360deg rotation and a certified accuracy of +/-5arc sec.
When combined for rotary alignment and vertical focussing applications, both stages share an overall working footprint of less than 210x250mm and a maximum height of less than 105mm.
They are said to be ideally suited to applications where the overall stack height of positioning systems needs to be kept at a minimum to reduce unwanted moment related compound positioning errors.
WaferMax-T and -Z stages employ direct-drive, brushless slotless servo motors to maximise positioning performance.
In direct direct-drive motor systems, the motor is directly coupled to the moving carriage or platen and the feedback encoder system with no backlash or wind-up as found with mechanical coupling based power transmission systems such as ballscrews or gearboxes.
The ironless motor design ensures that unlike iron cored motors, there is zero cogging; this exceptionally smooth operation eliminates torque ripple and ensures that the stage positions its load with extremely high precision and much improved repeatability, says the company.
WaferMax stages are well matched to applications requiring very tightly synchronised axis-to-axis and axis-to-sensor motion and where very accurate incremental steps must be combined with precise speed such as optical line scanning.
Direct-drive technology also allows high speed slewing for higher throughput, so that components may be rapidly pre-positioned before machining or that high speed precision contouring can be realised.
The WaferMax-Z vertical stage features a low profile wedge and base design secured in a preloaded cross roller bearing system with a lateral stiffness device used to minimise angular deviation during motion.
The 5mm travel range has almost perfect parallel motion and boasts impressive figures of 20arc-sec for pitch, roll and yaw with a positioning resolution of up to 0.83nm and calibrated bi-directional repeatability of +/-0.3um.
Stage speeds of up to 4mm per second and achievable with loading of up to 10kg with an integral pneumatic counterbalance.
The WaferMax-T rotary stage has a thick-walled, precision ground shaft and high-stiffness angular contact bearings for excellent wobble performance, high moment rigidity and reduced friction.
With its directly coupled, high-accuracy rotary encoder, the stage will provide a working resolution of up to 0.065arc-sec with the 10,000 line per revolution encoder option.
A 2048 line encoder option is also available.
The table top includes a standard mounting pattern for wafer-chuck mounting and its 25mm aperture allows product feed through or vacuum supply; an optional rotary union is available for applications where full rotation in combination with vacuum is required.
Specifications for wobble (20arc sec) and runout (5um - both axial and radial) are impressive and the maximum speed of 400rpm and 3kg axial loading figures all add up to make the WaferMax-T a very useable rotary positioning solution.
Both WaferMax stages have integral motor power and feedback connectors, making cable management very simple with easy integration into multi-axis stacked stages by either a service loop cabling arrangement or through an Aerotech cable management system (CMS) for a highly reliable solution.
WaferMax stages may be used on their own or in combination with other Aerotech sub-micron, linear X and Y stages along with associated drives and motion controls.
Combined load rating for WaferMax Z-Theta solutions is around 3kg and for applications beyond the recommended load, there are a number of vertical and rotary stage options that can be used.
For instance, the AVL 1000 series lift stages have direct-drive technology and comparable specifications to the -Z and can provide 50kg loading with up to 2mm of vertical travel.
Aerotech's largest direct-drive rotary stage, the ADRT series, has a similar specification to the -T and will position loads up to 173kg.
Aerotech's range of motion and automation control systems extend to software based solutions for complete machine control with up to 32 axis of motion with decentralised drives interfaced via an IEEE-1394 Firewire network with linked machine control function modules for HMI, PLC and Vision.
Typical systems are supplied complete and fully tested to the customer's specification with product training available and full pre- and post-sale technical support.
Along with motor power and encoder cables, all performance and calibration related documents are included, and a CD with full interconnection drawings helps system integrators with their own system documentation.
Also included is all set-up data for system configuration including servo tuning parameters, making system commissioning straightforward, requiring little more than connecting cables and applying power before programming application software.
These features are standard for every Aerotech product, ensuring that the true cost of ownership is extremely competitive, it says.
