Selective Chemical Stripping for Thin Metallic Finish Isolation
Selective finish stripping isolates thin gold or tin layers using ligand-accelerated redox baths while protecting nickel barriers through passivating inhibitors.
XRF Thickness Mapping
Metallic Measurement
X-ray fluorescence provides a non-destructive method for quantifying the elemental composition and depth of metallic layers deposited on electronic substrates. Technicians apply xrf thickness mapping to establish the spatial distribution of plated films across complex geometries such as printed circuit board pads or connector pins. It operates by directing a high-energy primary x-ray beam onto a target zone, which excites inner-shell electrons within the constituent atoms.
These atoms emit secondary photons at energies characteristic of their specific elements during the relaxation process. A semiconductor detector records these signals to calculate the mass per unit area. This technology applies exclusively to conductive materials and ceases to provide reliable data when film composition varies unknown.
Spatial Distribution
The process utilizes a motorized sample stage to move the board under a focused collimated x-ray beam at predefined coordinates. Software compiles the detected intensity counts from every point into a two-dimensional grid to visualize the topography of the deposition. Xrf thickness mapping detects plating nonuniformities caused by current density variations in electroplating baths.
The system resolution depends on the spot size of the beam and the counting duration at every location. Larger apertures allow for shorter collection times but forfeit the ability to resolve features on micro-vias or narrow traces. Operators correlate raw intensity values against calibration standards containing known layer thicknesses of equivalent materials to produce quantitative maps.
This technique identifies manufacturing defects like edge effect buildup or localized thinning before the assembly reaches the reflow oven where such variations affect solder wetting or joint strength.
Verification Protocol
Finished boards undergo this analysis to verify adherence to fabrication specifications for gold or nickel layers. Xrf thickness mapping confirms the uniformity of surface finishes across the entire surface area of a panel. Proper calibration ensures that the measurement remains independent of base metal substrate interference.
These data points provide objective evidence for process control within the plating line. Consistent application of this inspection method reduces the risk of intermittent connection failures at the component level. Proper control of this process ensures the reliability of every finished circuit.