Measurements of surface deformations and strains using an AFM moiré method

Abstract

An AFM (atomic force microscope) moiré method has been developed to measure surface deformations and strains. The scanning lines in the AFM monitor are used as the reference grating. The reference grating interferes with the specimen grating and forms a moiré pattern on the monitor. The condition of forming scanning moiré with an AFM is described. The deformation measurement principle using AFM moiré is discussed in detail. The AFM moiré method was used to measure the thermal deformations in QFP (quad flat pack) and BGA (ball grid array) packages. The experiment results verify the feasibility of the AFM moiré method and show its ability to measure the in-plane deformations and strains.

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“…Also, one challenge that remains in thin film technology, and more generally in microfabrication of components, is the characterization of performances (usually microstructural) at reduced scales. In this context, Moiré techniques combined with AFM have shown some results [30]; however, the experimental setup is quite cumbersome and the requirement of a fine grating leads to difficulties in the fabrication process and high costs. In addition, this method is not adapted for thin films studies.…”