Jakub CZAJKOWSKI^*, Tuukka PRYKÄRI, Erkki ALAROUSU, Jaakko PALOSAARI¹, and Risto MYLLYLÄ

Optoelectronics and Measurement Techniques Laboratory, University of Oulu, P. O. Box 4500, 90014 University of Oulu, Finland
¹Microelectronics and Materials Physics Laboratory, University of Oulu, P. O. Box 4500, 90014 University of Oulu, Finland

(Received September 17, 2009; Accepted January 3, 2010)

Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in printed electronics products' quality inspection is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, photonic crystal fibre and modified, free-space Michelson interferometer. Possibilities of the technique are demonstrated by analysis of an RF antenna — example of printed electronics products. Measurements were done with submicron axial resolution, offered by UHR-OCT system developed in our laboratory. Such high resolution is necessary due to the thickness of material layers used in printed electronics. In addition to tomography imaging, numerical results were compared with data provided by two commercially available measurement devices: Wyko NT3300 optical profiler and Dektak 8 stylus profiler (both Veeco). Comparison of profile heights and their spatial correlation is presented. Ability for full volumetric reconstruction and accuracy justified with reference measurements prove OCT to be a reliable tool in printed electronics product testing.

Key words: optical measurement, low coherence interferometry, non-invasive, imaging, printed electronics

^*E-mail address: jakub.czajkowski@ee.oulu.fi