Unveiling 3D Morphology of Multiscale Micro‐Nanosilver Sintering for Advanced Electronics Manufacturing by Ptychographic X‐ray Nanotomography

Abstract

The sintering processing–structure–property relationship of a multiscale silver materials is investigated: microparticles with nanofeatures, particularly on their three‐dimensional (3D) morphology. The target application is to replace conventional lead‐based solders in advanced electronic manufacturing. Unlike lead‐based solders, silver powders are suited to satisfy increasingly demanding mechanical, electrical, and thermal requirements, meanwhile being free of health effect. Sintering the material at a low temperature and without applied pressure are desirable conditions, which results in a preferred use of silver nanoparticles, as nanofeatures have higher driving force to sinter with the decrease in particle size. However, nanosized powders present potential health/environmental effects. To address the trade‐off between the benefits and shortcomings of nano‐ versus microparticles, this work studies a novel multiscale silver paste, namely micron‐sized powders with nanosized features. To get quantitative 3D visualization of micro‐ and nanoscale features, ptychographic X‐ray computed nanotomography is applied. The correlations between conditions (thermal aging, pressure, and substrate metallization), mechanical properties, and morphological parameters are established. Using novel 3D X‐ray nanoimaging technique, it is demonstrated that one can design multiscale materials while balancing complex demands required in advanced electronics manufacturing and research directions in materials design and characterization.

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

“…A densification process can occur at the same time due to the relatively high dealloying temperature of 800 °C, which corresponds to a homologous temperature ~0.57 for Ni− x Cr ( x < 20). Densification has also been observed in other porous metals’ coarsening processes at elevated temperatures 13 , 77 . Surface diffusion can only lead to morphological rearrangement and not a densification process, therefore other mechanisms must be considered here.…”

Environmental control for X-ray nanotomography

“…At SLS it is predominantly used for tomography of samples up to 150 mm in diameter with nanometric spatial resolution in the tender and hard X-ray regime, i.e. from 4.7 to 12.4 keV (Holler, Guizar-Sicairos et al, 2017;De Angelis et al, 2017;Lin et al, 2020). The acquisition of a single projection via X-ray ptychography can be as short as 10 s, but can also require up to 120 s depending on the experimental requirements.…”

“…This ensures a fair measurement comparison in terms of positioning and sample stability at low and high temperature. Future experiments will aim to study coarsening dynamics with nanoscale resolution (De Angelis et al, 2017;Furlan et al, 2018;Lin et al, 2020). The pore diameter in the nanoporous gold sample was determined to be $ 10 nm on average using electron microscopy, shown in Fig.…”

State-of-the-Art High-Resolution 3D X-ray Microscopy for Imaging of Integrated Circuits

“…The combination of volume and high resolution reachable via PXCT allowed understanding correlations between mechanical properties and morphological parameters to improve the designs of the material. [24] 3D PTYCHOGRAPHY WITH ZOOMING A clear disadvantage of PXCT for imaging parts of an integrated circuit is the e ortful sample preparation. A region of interest, limited in size, has to be selected prior to the measurement and extracted from the flat chip.…”