Market / Customer Need
What it is, what it does, why initiated.
|
Aerojet Ordnance are in business of producing kinetic energy projectiles for the US military. Part of the manufacturing process requires the application of a sputtered coating for corrosion resistance. This is created by sputtering from an alloy target onto the charges as they rotate past two magnetrons. The existing sputter cathodes had deteriorated and required replacing.
|
|
Project Details
What project involves R&D, design, testing ….
|
Gencoa were contracted to provide a ‘drop-in’ cathode design that would use all their existing connections for sealing and mounting and also enhance the target lifetime whilst maintain the coating performance to prevent corrosion of the substrates.
|
Initial Requirements
Materials, performance specs, standards, testing..
Aerojet had an established process and a requirement from their customer for the coating properties and the need to pass a quality assurance check via a salt-fog test. The time between target changes was to be increased by improving the target utilization and target width. By inspection of the chamber design it was apparent that the target width could be increased to 127mm (5”).
|
|
|
The maximum target thickness for a High Yield type of magnetic design of 15mm was adopted. The current design of target was directly water cooled, hence a water seal was broken during each target change. The new magnetrons were designed to use a thin cooling diaphragm that maintained the required power levels and avoided the need to break a water seal. Another aspect was to maintain a similar plasma impedance such that the existing power supplies were within the same operating voltage and power. This required measuring and matching the magnetic strength of the old cathodes with the new cathodes.
|
Difficulties Experienced
What uncertainty, materials, process, testing, cost implications
|
To make a full assessment of the system layout a Gencoa design engineer travelled to Aerojet to take measurements and check all the functions and water / power utilities. The main challenges related to the fit of the magnetrons to maintain the target position and use the existing connection ports (different for each magnetron). Also, the geometry of the substrate holder and the in-situ shuttering system meant that one magnetron required a different design of anode to prevent a clash with the shutters.
|
|
As there was a pre-qualified processes, the magnetics and plasma properties had to largely mimic the current environment around the substrates. This required magnetic modelling of the two magnetrons within the system to ensure that no plasma aberrations were caused.
|
Innovation
New innovative features – over state of the art for Gencoa / industry
|
The resulting products were much more user friendly than the older cathodes in that the target change frequency was double to previous and also the risk of a water leak had been removed during the target changeover. The time invested in carefully defining the system layout meant that the delivered magnetrons fitted well without any problems. The old magnetrons had suffered corrosion as the magnets were located in the cooling water. The new Gencoa cathodes located the magnetics in atmosphere and hence had no water contact.
|
|
|
|
Technology Improvement
How project has advanced tech / scientific knowledge
The project showed that an existing process can be successfully ‘copied’ when new cathodes are retro-fitted. This meant that the customer was straight back into production without the need to re-develop the process in anyway and that the risks were minimized. The doubling of the target life illustrated the improvement that can be made by the more complicated High Yield type magnetics when compared to the two pole magnetic designs.
|
|
Print