Application of highly focused, high frequency transducers for evaluation of near-surface flawsand thin packages: Smart cards, flip chip, flex circuits and thick films

摘要

Recently microelectronic components have become smaller, the internal alyers have become thinner and the details that need to be betected are minute. In order to achieve higher resolution in the acoustic images there has been a shift to higher frequencies (for applications such as flip chip interconnect). Conventional transducers are designed for penetration through relatively thick materials. However, when these are used to inspect near surface flaws or thin samples the ultimate resolution in the acoustic images is compromised due to attenuation of the signal in the fluid couplant path. Therefore, detectability of the pertinent details in thin samples with very small structures would not be optimum. However, the besign of the transducer can be altered and optimized for application to thin layer samples. This combined with a high acoustic frequency will produce very high definition acoustic images capable of detecting the defects of interest in thin layer devices. Illustrative example applications will be discussed in failure analysis of thin layer samples.