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Measure Thin Gold and Palladium Coatings on Leadframes

As the electronics industry makes use of ever thinner coatings, manufacturers increase their demands on measuring technologies to provide reliable parameters for product monitoring and control. The coating system Au/Pd/Ni is frequently used in the electroplating of leadframes, with CuFe2 (CDA 195) as substrate material. Typical coating thicknesses are between 3-10 nm Au and 10-100 nm Pd. For monitoring the quality of these coating systems, X-ray fluorescence instruments have established themselves as the measurement method of choice.

Comparative Testing to Determine the Capabilities of X-Ray Fluorescence

A series of comparative tests employing other physical measurement methods was used to determine the capabilities of X-ray fluorescence instruments within the mentioned ranges. Sample specimens were measured with the X-ray fluorescence method using the FISCHERSCOPEยฎ X-RAY XDVยฎ-SDD model, Rutherford backscatter and absolute, synchrotron radiation based X-ray.

Measuring Au Coating Thicknesses

For Au coating thicknesses of about 4, 6 and 9 nm, the results from the X-ray fluorescence instruments were all between the two other methods, with deviations in the sub-nm range, confirming not only the low scatter but also the trueness of measurements using X-ray fluorescence instruments. Traceability of the measurement results is ensured by using the FISCHER calibration standards developed specifically for this measuring application. The simple handling of X-ray fluorescence instruments also allows for easy scanning of a specimen to determine the homogeneity of the coating thickness, if required (see Fig. 2).

XRF Film Thickness Measurement, XDV SDD
ProductsXRF Film Thickness Measurement, XDV SDDXRF Film Thickness Measurement, XDV SDD

High-End Coating Thickness Measurement with Fischer Measurement Technology

The combination of state-of-the-art detector technology and the powerful analysis software, WinFTMยฎ, allows for reliable, accurate measurements of coating thicknesses even in ranges below 10 nm. For use on leadframes, the FISCHERSCOPEยฎ X-RAY XDVยฎ-SDD instruments are recommended for relatively normal-sized specimens; for very small structures, the XDVยฎ-ยต model, with its special X-ray optics, ensures a very small measurement spot of only 20 ยตm on the specimen.

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