Developing international specifications to achieve the ultra-high vacuums essential in advanced manufacturing processes
Ultra-high vacuums are essential in many of Europe’s precision manufacturing processes, including micro-electronics, complex coatings, or for the high-energy accelerators important in producing cancer therapies or used for advanced research. Improved vacuums lead to more cost-effective products and processes, thereby increasing EU competitiveness. To achieve the low operating pressures needed it is vital that only extremely clean materials and components are used inside these systems. Outgassed water vapour and hydrocarbon traces originating from component handling during manufacture, or from the packaging used for storage, can cause lingering contamination that damages products or reduces system performance. As components from many different suppliers are used for assembling such ultra-high vacuum systems each supplier is required to provide accurate component specifications. These include the material’s outgassing rate, as these rates influence the ultimate pressure and trace gas composition the vacuum system will achieve. Outgassing rates also effect the selection of vacuum pump size and hence the system’s operational energy requirements. Quadrupole mass spectrometers (QMS) are often used to determine outgassing rates but prior to this project these complex instruments suffered from a lack of characterisation and standardised methods. These methodologies also need to be underpinned by international documentary standards to enable the vacuum component supply chain to have confidence in the performance of new ultra-high vacuum systems so that more cost-effective products and processes can be implemented into the manufacturing industries. The previous EMRP project Vacuum metrology for production environments determined that the mass spectrometers used in high and ultra-high vacuum systems suffered performance changes during transportation between calibration labs and end user vacuum system installation, as well as over time and usage. The project overcame these issues by developing reference outgassing materials suitable for characterising QMS performance in situ along with a specification for calibrating these instruments.
Building on those results this EMPIR project worked closely with the International Standard Organisation (ISO) Technical Committee 11 Working Group 2 as well as the wider community of manufacturers, researchers and users of QMS. This led to the adoption by ISO of two Technical Specifications which have now been published as ISO/TS 20175:2018(E) and ISO/TS 20177:2018(E). These two closely related specifications, developed with the help of this project, will enable the improvement of materials used to create vacuums and make the control of partial pressures in industrial processes more reliable. They will also help manufacturers of QMS to improve the measurement performance of these devices. Extensive field testing will now follow, providing a route for the technical specification on QMS calibration and outgassing rate determination to be rapidly accepted and upgraded to ISO standard status. Project results will impact on the semiconductor and coating industries through improved gas consumption, and increased speed and productivity. Large accelerator and fusion facilities in Europe will also greatly benefit from traceable measurements of residual gases and outgassing of materials.