Micro Co-ordinate Metrolology

NPL is developing probes and probing strategies for use with small-scale or micro co-ordinate measuring machines (CMMs).

Overview

A consequence of the modern trend towards ever more miniaturisation is that the shape of key components, features on these components and assemblies of such components will need to be measured in three-dimensions. The development of probes and probing systems capable of making accurate, 3D measurements of micro-components and micro-structures with, in many cases, high-aspect-ratio features will be of vital importance to a significant number of firms in the micro-circuit fabrication and advanced sensor business sectors to enhance product quality and manufacturing process control.

To address the above metrological requirements NPL is developing a high accuracy 3D micro-probing system capable of incorporation into a commercial CMM. The work is being undertaken as part of a larger research theme aimed at overcoming the challenges arising in specialised areas where the metrology of small dimensions, masses and/or forces is key to the successful manufacture of innovative products.

Research

The current research project will develop a micro-probe system capable of making 3D measurements on miniature components with high aspect ratio features such as those typically found on MEMS or micro-fluidic devices. The probe element will consist of a flexure structure with integrated sensing and actuating elements, supporting a ball ended probe stylus. To overcome potential problems with surface adhesion that can restrict the performance of small contact probes the new micro-probe will be designed to vibrate. Dimensional constraints mean that the probe system is likely to be manufactured using microfabrication techniques.

The project work will be separated into three main stages:

1. Modelling and optimisation of the concept probe design
2. Micro-fabrication of a prototype concept probe
3. Evaluation of the prototype probe characteristics

The probe system will be packaged in such a way so as to be capable of integration into a Zeiss F25 CMM purchased a part of the CEMMNT Project

Links

• CEMMNT website
• High-accuracy co-ordinate metrology of small components

Publications

• Leach, R K, Chetwynd, D*, Blunt, L*, Haycocks, J, Harris, P M, Jackson, K, Oldfield, S, Reilly, S Recent advances in traceable nanoscale dimension and force metrology in the UK. Meas. Sci. Technol., 2006, 17, 467-476
• Leach, R K, Murphy, J The design of co-ordinate measuring probe for characterising truly three-dimensional micro-structures. 4th euspen International Conference, Glasgow, UK, 31 May 2004 - 2 June 2004, 230-231

Collaboration

• This project has support from the EPSRC-funded Grand Challenge Project (EP/E001904/1)
• University of Greenwich – probe system modelling and design optimisation (www.gre.ac.uk)
• University of Cambridge – micromachining of flexure component manufacture (www.cam.ac.uk)
• Cranfield University – piezoelectric deposition on flexure component (www.cranfield.ac.uk)
• University of Nottingham – micromanipulation/assembly of the microprobe components (www.nottingham.ac.uk)
• NPL is also collaborating with the University of Taipei on ball and stem manufacture
• Zeiss are also supplying the F25 CMM and will be collaborating on probe development
• DMAC/EMAN |  MNT Measurement Club