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Thin film coating

Edwards vacuum solutions for innovative thin film technologies

Thin film coating technology has become a very important part of our lives in every aspect be it in consumer applications like spectacle glasses or frames, mobile phones, camera lens, food serving metallised sachets, doorknobs, decorative figurines or in industry applications for solar panels to retain the light energy as well as in manufacture of electronic circuits. The usage is widespread and is supporting feature for many everyday objects. 

Thin film coating

The list is endless with new processes being discovered on a regular basis for deposition of metals, compounds, or oxides on to substrates like, metals, plastics or ceramics and modifying the surface characteristics of these substrates, and changing the properties like transmission, reflection, hardness, resistance, absorption, corrosion, and electrical behavior. Some few examples include improved accuracy and sensitivity of medical and environmental sensors, low emissivity glasses, eyeglasses with antireflection coatings, anti-fingerprint coatings for touch screen, protective (DLC) coatings for car cameras, diffusion barrier for food packages, water repellent surfaces, tribological coating for protheses, vivid colors and graphics on smartphones and higher efficiency yield for solar panels. 

How does thin film coating work?

Thin film deposition techniques can be in simple terms divided between Physical and Chemical processes. 

Physical Vapour Deposition and Chemical Vapour Deposition

Physical Vapour Deposition (PVD)

This involves vaporisation of a material from the solid state and condensation on to substrate at a lower temperature. These processes typically take place under high vacuum environment. In a nutshell, there are various PVD processes mainly depending on vaporisation technique:

  • Resistive heat source
  • Electron beam
  • Electrical arc discharge
  • Magnetron plasma sputtering
  • Ion beam sputtering

PVD coaters can also be segmented according to their construction design:

  • Batch coaters or box coaters: products are loaded and unloaded after each deposition process.
  • Roll to roll coater: a source flexible rolled substrate is continuously fed into the coating process chamber and then rewound on a separate roll before being taken out when process is complete.
  • In-line coaters: True continuous coaters for high throughput requirements, where product is loaded into the entry chamber also called as the loading chamber and goes out through the exit chamber also called as unloading chambers.

Chemical Vapour Deposition (CVD)

This is a deposition technique where the source material, or precursor, is introduced into the chamber or reactor in the gaseous phase, usually chemically reacting with other gases before condensation on the substrate. These processes typically take place at 10-3 mbar and above. Chemical deposition processes depend on how the reaction is enabled, simple thermal reaction or with assistance of a reduced pressure (LPCVD) or with a plasma assistance (PECVD or PACVD). Recent advancements in Atomic Layer Deposition (ALD) and Liquid Phase Epitaxy processes have been gaining momentum in the electronics sector.

The role of vacuum technology for thin film coating

Vacuum technology is critical to these processes as the vapours of these materials are required to flow unhindered without impurities in low pressure atmospheres on to the substrates, or just to enable process conditions like with a plasma. Therefore, creation of vacuum and monitoring the pressures are extremely important to these processes.

Edwards has been forefront in the thin film industry by continuously developing broad range of vacuum solutions - primary vacuum pumping systems, secondary vacuum pumps, vacuum instrumentation, and control systems over the years to meet the stringent requirements of diverse coating processes. Whether it is managing fast pumping cycles demanded by glass and solar coating process or managing the harsh processes in ALD or LPE applications, we have optimised vacuum solutions to meet your requirements.

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