Known for innovation, Swiss firm Schneeberger AG Lineartechnik is currently developing a new positioning and movement system that will bear the name Double Gantry. Initial tests and analyses prove that speed of positioning can be almost doubled in applications such as wafer production. The Double Gantry should be on the market from mid-2014.
Mobile telephones, tablets, laptops and many other, routine electronic products are becoming ever more efficient and/or smaller. This is due to the semiconductor chips, miniaturisation of which seems to be endless. Inserting and testing structures (data highways) in these tiny electronic parts requires systems whose accuracy of movement has to be within micrometres and nanometres. The major chip manufacturers also expect optimum speed, as this has a direct impact on profit. In addition to the optical system, in order to best satisfy the requirements efficient positioning units are in great demand in production and test facilities. They ensure that the wafers dotted with hundreds of chips are quickly and accurately positioned.
Schneeberger AG is a leading provider of such movement systems. Markus Kindler, the company’s Engineering Systems Manager, explains: “There are major differences between the precision requirements of our customers and end users. Ever greater positioning accuracy, which falls within tolerances of tens or hundreds of nanometres for a movement area of 250,000 mm2 is, however, expected with progressive miniaturisation.” To explain: the ratio between a nanometre and a metre is roughly equivalent to the difference between the size of a hazelnut and the Earth.
Double Gantry: less weight, more speed
With their sights on greater efficiency, Schneeberger’s engineers are currently developing a new positioning system, which has already been comprehensively tested. The initial results are a reason for Markus Kindler to expect a real quantum jump in terms of increased performance: “We are assuming that the Double Gantry will double positioning speed in semiconductor chip testing, which will ultimately considerably increase productivity.”
The name Double Gantry reflects the decisive technical principle: two gantry axes are used. The X and Y axes are uncoupled. This is possible by arranging them in a cross and achieving independent movement through multiple guide rails. This innovative structure means the lower axis does not have to bear the weight of the upper axis, which massively reduces the lower axis’s speed in the usual stacked configuration. In the Double Gantry, the X and Y axes each bear their own weight, as well as that of the axis of rotation, the wafer and the clamp system.
Best values in terms of speed to precision
Speed and precision are equally important for achieving a high production speed. In the final analysis it’s a question of approaching clearly defined structures as quickly and accurately as possible. Production speed suffers if a positioning system moves quickly to a defined position, but has to be adjusted there for a long time due to lack of precision. It is therefore worth approaching the predefined structures quickly and accurately.