Decoupling Sub-micron Resolution and Speed from Sample Size in 3D X-ray Imaging

Abstract

X-ray imaging (2D & 3D) has been one of the primary non-destructive analysis methods for electronic packages and printed circuit boards (PCB) for over three decades. The continually shrinking features and growth of heterogeneous packaging and wafer-level packaging drive urgent demand for even higher resolution but on larger samples, including larger packages and on wafers. Currently, gaps in non-destructive 2D and 3D imaging in failure analysis exist due to lack of resolution to resolve sub-micron defects typically found in most cracks or voids in microbumps less than 30 microns in diameter and on low contrast materials such as defects in organic substrates. The larger form factors of samples including modern heterogeneous packages, PCB, wafers adds yet another layer of difficulty, and submicron lengthscale defects on such samples are far beyond the resolution power of most existing 2D or 3D X-ray tools. Conventional, high resolution 3D X-ray tools are designed to inspect small packages, but as sample size increases, the time to detect small defects in large packages or PCB may run into several hours or days, rendering this application impractical. We describe a novel 3D X-ray tool that overcome the sample size and speed limitation of traditional X-ray imaging systems. Time to obtain a sub-micron resolution imaging on a region of interest in a package, pcb or 300 mm can be completed within a few minutes. The rapid multiresolution capabilities are also well suited for construction analysis or reverse engineering from packages to pcbs.