Ald
Atomic Layer Deposition (ALD) is a vapor-phase thin-film process that deposits material one atomic layer at a time using sequential, self-limiting surface reactions. Precursor gases pulse alternately and purge between pulses, so film growth is controlled by cycle count rather than line-of-sight exposure. This yields exceptionally uniform, conformal coatings on complex, high-aspect-ratio geometries.
On the shop floor, ALD is not a material-removal step but a post-process coating technology for parts requiring ultra-thin, conformal films over edges, channels, recesses, or high-aspect-ratio features. Where spray, plating, or CVD leave shadowing or thickness variation, ALD deposits uniformly because each precursor pulse reacts only with available surface sites before being purged. Operators run the system like precision metrology: they control cycle count, precursor chemistry, purge timing, temperature window, and surface readiness. Part cleanliness is critical; residual coolant, oil, fingerprints, or oxide can block nucleation and produce patchy films. ALD can deposit oxides, metal nitrides, and metals at low temperatures, which helps when substrates are thermally sensitive or dimensional stability matters. In CNC work, tolerances remain relevant because even nanometre-scale films affect fits, clearances, seals, electrical performance, or tribology. For millwork and architectural fabrication, ALD is niche and unsupported for routine cabinetry operations.
What makes ALD different from CVD?
ALD alternates precursor pulses with purge steps so the reactants never meet in the gas phase, while CVD relies on concurrent precursor availability. This sequential, self-limiting chemistry gives ALD atomic-scale control and high conformality.
Why is ALD valuable on complex parts?
Because the reactions are self-limiting, the film coats deeply recessed or high-aspect-ratio surfaces more uniformly than line-of-sight processes such as evaporation or sputtering. ALD therefore covers edges, pores, channels, and trenches evenly without shadowing.
What determines final film thickness?
Primarily the number of ALD cycles, with film growth per cycle governed by precursor chemistry and surface saturation behavior. Operators control thickness by setting cycle count while optimizing purge timing, temperature, and surface readiness.