The major interest presented by a Scanning Acoustic Microscope (SAM) for microassembling technologies is to characterize system integrity without alteration in internal structures of the different samples. But ultrasonic waves nature, propagation diversity and spatial resolution obtained close to optical one, induce instructive information contained into images. So the interpretation quality images will be directly linked with samples nature, used tool thorough and spatial ultrasonic probe resolution. In this paper, we present first an analytical approach of spatial resolution of SAM. Moreover, we propose calculations about field depth within media. Then, we correlate theoretical results by performing tests on special calibrated samples with two microscopes: commercial one and specific acoustic system developed in IXL Laboratory. In a second time, we characterize few microassembling technologies with two techniques: A-SCAN and C-SCAN analysis modes. Both methods highlight some differences in ability detection of weak defects due to highest interface view (best resolution and contrast) in particular with the C-SCAN mode. In fine, we show typical microassembling technologies analysis and we conclude about the place of SAM in failure control and reliability analysis.