Residual stress and thermally induced warpage are critical reliability concerns in power electronic packaging, particularly when employing sintered copper nanoparticle (Cu NP) interconnects. While these interconnects provide high thermal and electrical performance, they also introduce significant interfacial stresses during bonding that alter mechanical behavior during service. This study develops an integrated confocal Raman–analytical modeling framework to directly quantify and mechanistically interpret these stresses in a representative SiC/Sintered Cu NPs/Active Metal Brazing ceramic substrate (AMB) stack. Raman spectroscopy reveals a compressive interfacial stress field peaking at −334 MPa near the chip center with localized hotspots linked to microporosity. Complementary in-situ Moiré interferometry tracked warpage evolution during thermal cycle (30–310°C). Coupling this stress measurement with a three-dimensional thermoelastic model, and explicitly assigning the bonding temperature as the stress-free reference, enables accurate reproduction of the temperature-dependent warpage trajectory. The model predictions align with experimental interferometry within < 5% deviation. These results demonstrate that incorporating residual stress is essential to realistically capture thermo-mechanical evolution. The proposed Raman–model paradigm advances beyond prior purely numerical or purely experimental efforts by bridging quantitative stress mapping with predictive warpage modeling. This methodology provides essential insights for thermal-induced residual stress and warpage managements in high-temperature power electronics packaging, providing a stress-informed foundation for reliability assessment and design optimization.

Pressureless sintered silver paste is widely used in SiC power electronic packaging for its superior thermal and electrical properties, enabling efficient heat dissipation and improved device reliability. Current thermal conductivity models frequently assume isotropic thermal behavior to simplify heat transfer calculations, yet these models neglect the inherent anisotropic porosity of sintered silver materials. This omission introduces errors in the characterization of these materials' thermal performance. This research investigates how the spatial anisotropic distribution of pressureless sintered silver's microstructure impacts QFN packaging's overall thermal conduction performance. This investigation is achieved by comparing lateral/vertical porosity differences between two materials and applying multidimensional thermal conductivity modeling. Two types of pressureless sintered silver were employed as die-attach materials to fabricate SiC MOSFET-based QFN packaging. The sintered microstructures' lateral and vertical cross-sections were characterized using scanning electron microscopy (SEM), enabling quantitative extraction of anisotropic porosity distributions. Subsequently, a numerical model was developed using the extracted porosity data to enhance the accuracy of heat transfer predictions in sintered silver layers while considering anisotropic thermal conductivity. Thermal resistance characterization was conducted on two QFN packages, and the accuracy of the proposed modeling methodology was validated by establishing the interrelation between experimental thermal resistance measurements and theoretical thermal conductivity predictions. This study demonstrates a refined approach to evaluating and optimizing sintered silver materials, providing a more accurate and application-driven thermal management strategy for SiC MOSFET power packaging.

In harsh offshore environments, large-area sintered nano-copper (Cu) interconnections, which serve as die attachment material or thermal interface material (TIM), are prone to degradation from hydrogen sulfide (H2S) corrosion. This study introduced a film-forming technique based on atmospheric pressure plasma jet (APPJ) to improve the corrosion resistance of large-area sintered nanoCu joint. The corrosion protection mechanism against H2S-containing atmospheric corrosion was investigated using both experimental methods and density functional theory (DFT) simulations. The key findings were as follows: (1) The deposition film, primarily composed of a Si-O3 network, effectively protected sintered Cu plate from corrosion by H2S gas, and maintaining the mechanical performance of sintered Cu joint after 384 h of H2S testing. (2) The dissociation products of the APPJ-treated precursor hexamethyldisiloxane (HMDSO), −OSiCH3 and −OSi(CH3)3, formed stable chemical bonds on the sintered nanoCu surface, resulting in the formation of −OSiCH3(O-CH3)2 fragments. (3) The −OSiCH3(O-CH3)2 fragments were unreactive toward to corrosion agents such as H2S, O2, and H2O, and also serving as a barrier to block their access to the sintered nanoCu surface. This study provided a comprehensive understanding of the corrosion protection mechanism of sintered nanoCu using APPJ-deposited films, offering valuable insights for improving the reliability of power electronics.