James D. Claverley

Advances in engineering nanometrology at the National Physical Laboratory

The National Physical Laboratory, UK, has been active in the field of engineering nanometrology for a number of years. A summary of progress over the last five years is presented in this paper and the following research projects discussed in detail. (1) Development of an infrastructure for the calibration of instruments for measuring areal surface topography, along with the development of areal software measurement standards. This work comprises the use of the optical transfer function and a technique for the simultaneous measurement of topography and the phase change on reflection, allowing composite materials to be measured. (2) Development of a vibrating micro-CMM probe with isotropic probing reaction and the ability to operate in a non-contact mode. (3) A review of x-ray computed tomography and its use in dimensional metrology. (4) The further development of a metrology infrastructure for atomic force microscopy and the development of an instrument for the measurement of the effect of the probe?surface interaction. (5) Traceable measurement of displacement using optical and x-ray interferometry to picometre accuracy. (6) Development of an infrastructure for low-force metrology, including the development of appropriate transfer artefacts.

Modelling the Interaction Forces between an Ideal Measurement Surface and the Stylus Tip of a Novel Vibrating Micro-scale CMM Probe

This paper describes the development of an analytical model to describe a novel three-axis vibrating micro-scale probe for micro-co-ordinate measuring machines (micro-CMMs). The micro-CMM probe is vibrated in three axes, in order to address the problems inherent with micro- and nano-scale co-ordinate measurements caused by surface interaction forces. These surface forces have been investigated and a mathematical model describing an ideal probing situation has been developed. The vibration amplitude required for the probe to overcome the surface interaction forces has been calculated using this model. The results of initial vibration experiments are reported and the suitability of the probe to counteract the surface interaction forces is confirmed.

Assembly of a novel MEMS-based 3D vibrating micro-scale co-ordinate measuring machine probe using desktop factory automation

In this paper the assembly of a novel micro-scale coordinate measuring machine (CMM) probe is considered. A working micro-scale CMM probe is assembled from a MEMS device and a stylus produced by micro-electro-discharge machining. The production technique of the micro-scale parts is discussed and two methods for assembly are presented.

Semi-automated Assembly of a MEMS-Based Micro-scale CMM Probe and Future Optimization of the Process Chain with a View to Desktop Factory Automation

The assembly process of a novel micro-scale co-ordinate measuring machine probe is presented. The process makes use of a semi-automated miniature robot. The initial tests that led to the full process chain are described, and the full process chain presented. The presented process chain successfully produced four assembled probes. Future work is suggested to augment the presented process chain leading to further automation.

Reduced order modelling for risk mitigation in design of miniaturised/integrated products

A numerical modelling methodology for the embodiment design of three-dimensional miniaturised/integrated products is developed and demonstrated. The focus is on the numerical techniques and methods that underpin the development of reduced order models (ROMs). These models are used together with methods for estimating variations in performance/quality characteristics and probabilistic optimisation to aid sensitivity, product capability and risk mitigation analyses. The numerical techniques comprising the design methodology are demonstrated with examples related to the design of a novel three-dimensional vibrating micro-probe.

Numerical modelling methodology for design of miniaturised integrated products - an application to 3D CMM micro-probe development

This paper presents an integrated numerically-driven modelling methodology for the design of miniaturised/integrated (Mintegrated) products and the selection/control of associated manufacturing processes. The focus is on the numerical techniques and methods that underpin several design procedures aiding the embodiment design stage of product development. A design assistant tool is developed as an end-user navigation interface that captures recommended design activities for the development of novel micro-integrated products and the supporting tools for their realisation. The main focus is placed on those design procedures comprising numerical methods for the simulation and modelling of the performance and behaviour of a product or process, and the analysis of their design in terms of risk of failure, capability of satisfying specification limits and optimality. The methodology enables an efficient and fast design process and can be applied to a wide range of micro-product developments. The applications range from the fabrication of micro- and nano-scale structures and components for heterogeneous systems, to micro-fluidics, metrology and embedded test devices. In this study, a number of design procedures and associated numerical techniques are demonstrated for the design of a new three-dimensional coordinate measuring machine (CMM) micro-probe developed at the National Physical Laboratory (NPL, UK).

Utilisation of FIB/SEM Technology in the Assembly of an Innovative Micro-CMM Probe

The measurement of features from the micro- and precision manufacturing industries requires low uncertainties and nano-scale resolution. These are best delivered through ultra precise co-ordinate measuring machines (CMMs). However, current CMMs are often restricted by the relatively large and insensitive probes used. This paper focuses on the assembly challenges of a novel micro- CMM probe. The probe is comprised of a 70 μm glass sphere, attached to a solid tungsten-carbide shaft of diameter less than 100 μm, joined to a piezoelectric flexure structure. The assembly requirements are for positional accuracy of ±0.5 μm, angle between the shaft and flexure of 90°± 0.29° and that the components be undamaged by the process. A combined Focused Ion Beam and Scanning Electron Microscope machine (FIB/SEM) with integrated nanoresolution manipulators was used. The investigation has evaluated potential assembly and joining solutions, identified modifications to existing equipment and product design and produced a set of prototypes.

Chapter 9 – Coordinate Metrology

This chapter discusses coordinate metrology, both macro-scale and micro-scale. Co-ordinate measuring machines, both mechanical and optical are discussed. Different CMM probing systems are addressed along with CMM software and error sources. CMM calibration, performance verification and traceability are also discussed, along with the latest specification standards in this area, and the difference between prismatic and freeform measurements. Micro-CMMs are addressed next: micro-CMM types, probing systems, performance verification and calibration.

Testing the Mechanical Characteristics and Contacting Behaviour of Novel Manufactured and Assembled Sphere-Tipped Styli for Micro-CMM Probes

The effectiveness and versatility of the probes used on micro-co-ordinate measuring machines is currently limited by the dimensions, geometry and quality of the spherical stylus tips available. A shaft fabrication and gluing process is demonstrated to assemble a sphere-tipped stylus for tactile micro-co-ordinate measuring machine probes. The contact behaviour of the manufactured micro-styli is investigated both in a static and a vibrating mode. The ultimate strength of the glue joint is also investigated. It is concluded that the assembly of styli using the presented method is viable, however, that stylus shafts below 40 μm diameter may require new manufacturing methods.