A warpage measurement system with large dynamic range for boards with components

摘要

A new algorithm for carrier removal, a key step in the Fourier transform method of fringe pattern analysis, is presented in this paper. The accuracy of frequency estimations is critical to carrier removal to avoid potential significant errors in the recovered phase. A new algorithm on Fourier transform and curve fitting technique is developed. To avoid an ill-conditioned result in solving the least-square problem, an orthogonal polynomial curve fitting algorithm is developed. A new system that combines projected grating moir, (PM) with shadow moir*(SM), recently designed and built with large dynamic range for both component level and board level warpage measurement for the reliability study of electronic packaging materials and structures, is presented and demonstrated.