Investigation of moisture-induced crack propagation in the soft-termination multi-layer ceramic capacitor during thermal reflow process

Abstract

Purpose This study aims to investigate crack propagation in a moisture-preconditioned soft-termination multi-layer ceramic capacitor (MLCC) during thermal reflow process. Design/methodology/approach Experimental and extended finite element method (X-FEM) numerical analyses were used to analyse the soft-termination MLCC during thermal reflow. A cross-sectional field emission scanning electron microscope image of an actual MLCC’s crack was used to validate the accuracy of the simulation results generated in the study. Findings At 270°C, micro-voids between the copper-electrode and copper-epoxy layers absorbed 284.2 mm/mg3 of moisture, which generated 6.29 MPa of vapour pressure and caused a crack to propagate. Moisture that rapidly vaporises during reflow can cause stresses that exceed the adhesive/substrate interface’s adhesion strength of 6 MPa. Higher vapour pressure reduces crack development resistance. Thus, the maximum crack propagation between the copper-electrode and copper-epoxy layers at high reflow temperature was 0.077 mm. The numerical model was well-validated, as the maximum crack propagation discrepancy was 2.6%. Practical implications This research holds significant implications for the industry by providing valuable insights into the moisture-induced crack propagation mechanisms in soft-termination MLCCs during the reflow process. The findings can be used to optimise the design, manufacturing and assembly processes, ultimately leading to enhanced product quality, improved performance and increased reliability in various electronic applications. Moreover, while the study focused on a specific type of soft-termination MLCC in the reflow process, the methodologies and principles used in this research can be extended to other types of MLCC packages. The fundamental understanding gained from this study can be extrapolated to similar structures, enabling manufacturers to implement effective strategies for crack reduction across a wider range of MLCC applications. Originality/value The moisture-induced crack propagation in the soft-termination MLCC during thermal reflow process has not been reported to date. X-FEM numerical analysis on crack propagation have never been researched on the soft-termination MLCC.

Deformation and crack growth in multilayered ceramic capacitor during thermal reflow process: numerical and experimental investigation

“…The vapor pressure generated induces stresses that reduce the fracture toughness of the device (Kastratović et al , 2020). The reduced fracture toughness due to the induced pressure can aid the formation of structural defects (Cheng and Guo, 2003; Bachok et al , 2023). MLCC solder joint can also be impacted when subjected to vacuum and hot air reflow processes (Hong et al , 2021).…”

“…Despite the notable contributions in the literature on fracture mechanics of electronic packages, a few research studies (Ahmar and Wiese, 2017; Ng et al , 2022; Bachok et al , 2023; Jin Kim et al , 2007; Tao et al , 2017; Apalowo et al , 2023) exist on the experimental study of thermally reflowed ceramic capacitors. Furthermore, a limited number of works (Ng et al , 2022; Bachok et al , 2023; Apalowo et al , 2023) considered the fracture growth phenomenon during thermal reflow of soft-termination MLCCs. Also, only one (Apalowo et al , 2023) of the limited studies subjected the soft-termination MLCC to multiple (accelerated) thermal reflow.…”

“…Considering the significant impact of subjecting the MLCC to an accelerated thermal reflow on its thermal reliability (IPC/JEDEC, 2023), the current work investigates fracture deformation and delamination cracks in soft-termination MLCC when subjected to an accelerated thermal reflow. The current work also examines the growth mechanism of the interfacial crack; this was not considered in the previous works (Ng et al , 2022; Bachok et al , 2023; Apalowo et al , 2023) on the subject matter.…”