1 This was presented as poster in 9th International Symposiaum on Measurement and Quality Control 2007(9th ISMQC) from 21-24th November, 2007 at IIT Madras, India. MICRO-CMMS FOR THE DEVELOPMENT OF MICROSYSTEMS TECHNOLOGY Samik Dutta Scientist-B, Metrology Group, Central Mechanical Engineering Research Institute, Durgapur-713209, India E-mail: s_dutta@cmeri.res.in Ranjan Sen Scientist and Head, Metrology Group, Central Mechanical Engineering Research Institute, Durgapur-713209, India E-mail: rsen@cmeri.res.in Abstract: The recent surge of making engineering components in microscale level has given a new challenge to metrologists to measure in meso and micro scale. Keeping the general advantage of coordinate measuring machine over conventional measuring equipment, worldwide activities are going on to develop micro-CMMs in the range of, say, 252510 mm and the resolution of about 1 nm. This paper deals with the important attributes of a micro-CMM, which is to be capable of measuring sub-micron accuracy intricate parts with minimum settings. Review of several frontier technologies in this field have been made here in order to focus the advantages and disadvantages of the various systems already developed or in the verge of development. Keeping in view the best technology and also the cost involved in such development work CMERI’s choice to embark on this emerging technology has also been discussed. Key words: Micro-CMM, LDGI, Parallel Kinematics , Interferometer. 1. INTRODUCTION: Of late many engineering components are designed and fabricated in miniaturize size in order to get technical benefits like inertia effect, surface tension effect, minimization of energy, accessibility to the intricate locations, minimization of material cost etc. However, the complexity in manufacturing and measuring geometrical and dimensional features of these parts expands exponentially with the reduction of size. One answer to the measurement problem is the development of a micro- CMM which will have all the benefits of a conventional CMM in addition to nano scale resolution both in linear and angular measurements. However, whatever work has been done till date in this nascent machine development field, the main limitation is the machine’s accuracy and repeatability. While scaling down a conventional CMM in design, the three main features of a CMM, viz. the main structure, the probing system and the positioning control system are of vital importance. From plane bridge structure to arch bridge structure have been found most suitable for the present demand. Technology for probing systems has developed from less accuracy touch trigger probing , laser scanning probe, confocal probing, AFM probing in tapping mode, SEM probing, high accuracy capacitance displacement transducer probing system to an autofocus sing probing system. The positioning technique is also improving from parallel kinematics, Laser interferometric, Laser Diffraction Grating interferometric in combination with piezo stage. 2. DIFFERENT BREED OF MICRO-CMMS : 2.1. Non-contact type micro-CMM: A high precision micro-CMM (coordinate measuring machine) is under development by Fan et al [1] with the expected measuring range of 25 mm25 mm10mm and the resolution of 1 nm. To achieve this, an arch-bridge is used instead of the conventional rectangular bridge to get the minimum deflection with the central load of probe. Under the same dimension and the same spindle load, the maximum deflection at the center of the arch-bridge can be reduced by more than two times. It is made of granite material. The total weight is about 40 kg. The spindle adds additional weight of about 3 kg. In the positioning system a co-planar stage is proposed here. The stage is moved along the precision ground rod of the frame in the X- direction, and the frame is moved in the Y-direction along the precision ground rod of the base. Four gliding rods are located in the same plane. The X-table is embodied in the Y-frame and the Y-frame is embodied in the base. Such a design can compress the whole stage into a single layer. It can significantly reduce the Abbe´ error in the vertical direction. Each axis motion is actuated by a motor from one side and its motion is detected by a holographic grating scale from the other side as shown in Fig 1a.