ISO 18452:2005

Overview

ISO 18452:2005 specifies a standardized method to determine the thickness of fine ceramic films and ceramic coatings using a contact‑probe profilometer (stylus profilometer). The method is intended for thin films in the nominal range 10 nm to 10 000 nm, requiring a clearly defined boundary between coated and uncoated substrate areas. The standard defines measurement principle, apparatus requirements, specimen preparation, test procedure, calculation method and reporting.

Key Topics and Requirements

• Measurement principle: Step‑height measurement by scanning a stylus across the coating edge and calculating the vertical difference at the inflection point of the profile.
• Measurement range: Suitable for 10–10 000 nm film thicknesses; under optimal conditions profilometers may resolve steps of only a few nanometres, though accuracy degrades at very small thicknesses.
• Apparatus:
  • Contact‑probe profilometer conforming to ISO 3274.
  • Diamond stylus with conical tip (vertical angles 60° or 90°) and tip radii typically 2 µm, 5 µm, 10 µm or 12.5 µm.
  • Instrument calibration using step‑height calibration standards; calibration conditions should match measurement conditions.
• Test specimen & surface:
  • Distinct coated/uncoated boundary required.
  • Surface roughness (Ra) of substrate and coating should be ≤ 1/5 of the step height.
  • Average roughness wavelength should be < 10% of the measured sampling lengths on each side of the step.
  • Minimum of three test pieces; perform five scans per piece (15 values total).
• Procedure:
  • Level the sample (avoid levelling errors that bias thickness - Annex A discusses amplification and tilt effects).
  • Use low stylus loading (0.05 mN to 0.3 mN), scan perpendicular to the step from coated to uncoated side.
  • Calculate thickness by fitting least‑squares lines to representative regions and taking the vertical difference at the inflection x‑position.
• Reporting: Include calibration materials, stylus radius and loading, measurement length/magnification, individual measurements (≥5 per specimen), average thickness and optional standard deviation, and any test comments.

Applications

ISO 18452 is essential for:

• Quality control of thin ceramic coatings (oxides, carbides, nitrides) in electronics, optics and wear‑resistant surfaces.
• Metrology laboratories performing film thickness measurement and certification.
• R&D and process control in PVD/CVD sputtering processes where accurate coating thickness and step‑height data are required.
• Manufacturers of advanced ceramics and coated components needing reproducible, traceable profilometric data.

Related Standards

• ISO 3274 - Geometrical Product Specifications (GPS) - Surface texture: profile method - contact stylus instrument nominal characteristics (referenced for profilometer specifications and calibration).