Effects of Moisture Diffusion on a System-in-Package Module by Moisture–Thermal–Mechanical-Coupled Finite Element Modeling

Abstract

Epoxy molding compounds (EMCs) are commonly used in electronic products for chip encapsulation, but the moisture absorption of EMC can induce significant reliability challenges. In this study, the effects of hygrothermal conditions and structure parameters on moisture diffusion and the consequent influences (such as moisture content on die surfaces and stress distribution) on a system-in-package module have been systematically investigated by moisture–thermal–mechanical-coupled modeling. Hygroscopic tests were carried out on a new commercial EMC at 60 °C/60% RH and 85 °C/85% RH, followed by evaluations of diffusion coefficients by Fick’s law. It was found that the moisture diffusion coefficients and saturation concentrations at 85 °C/85% RH were higher than those at 60 °C/60% RH. From the modeling, it was found that the consequent maximum out-of-plane deformation and stress of the module at 85 °C/85% RH were both higher than those at 60 °C/60% RH. Influences of thicknesses of EMC and PCB on the moisture diffusion behavior have also been studied for design optimization. It was found that the maximum moisture concentration on die surfaces and resultant stress increased notably with thinner PCB, whereas the effects of EMC thickness were limited. This can be attributed to the comparison between the thicknesses of EMC and PCB and the shortest existing diffusion path within the module. These findings can provide helpful insights to the design optimization of electronic modules for hygrothermal conditions.

Delamination of Plasticized Devices in Dynamic Service Environments

“…The non-airtightness of the plastic seal causes the intrusion of a large number of nonpolar molecules and polar molecules along the micropores, including O2, which can undergo oxidation reactions, and H2O, which can undergo corrosion reactions [44,45. One of the well-established mechanisms in the research field is the oxidation of the copper substrate in the plasticized copper substrate or the RDL (ReDistribution Layer) in the presence of O2 and water molecules carrying Na + , Cl − , and other impurity ions through the chip passivation layer, and the metal-layer corrosion reaction [13][14][15][16][17][18][46][47][48], as shown in In 1972, Sharpe proposed the interphase concept to describe the transition regi the interface between two phases of different materials [50]. At the EMC/Cu inte when the oxide thickness of the Cu substrate is in the range of 20-30 nm, the increa surface roughness leads to the enhancement of the binding at the two-phase inte In 1972, Sharpe proposed the interphase concept to describe the transition region at the interface between two phases of different materials [50].…”

“…Explaining the delamination phenomenon from the stress–strain perspective alone, it has been found that, at the delamination interface, mainly due to the interface between the two phases of the material, the plastic deformation of the two-phase material is formed under the action of the alternating shear stress, which ultimately leads to the failure of delamination [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. At the same time, under the intrusion of moisture, ionic contaminants corrode the chip, and moisture thermal expansion is also the main reason for the device to appear to suffer from the “popcorn” effect [ 15 , 16 , 17 , 18 , 19 ]. However, with the continuous development of advanced encapsulation technology, the delamination mechanism of encapsulated devices should be more than limited to the macro-scale, and the micro-delamination mechanism also needs to be gradually improved, with a view to establishing a perfect delamination prevention, identification, and improvement mechanism.…”

“…Chemical Damage by MoistureThe non-airtightness of the plastic seal causes the intrusion of a large number of non-polar molecules and polar molecules along the micropores, including O 2 , which can undergo oxidation reactions, and H 2 O, which can undergo corrosion reactions[44,45]. One of the well-established mechanisms in the research field is the oxidation of the copper substrate in the plasticized copper substrate or the RDL (ReDistribution Layer) in the presence of O 2 and water molecules carrying Na + , Cl − , and other impurity ions through the chip passivation layer, and the metal-layer corrosion reaction[13][14][15][16][17][18][46][47][48], as shown in Figure4. However, the effect of thermal oxidation of epoxy resin in the presence of O 2 and H 2 O on its adhesion is less mentioned.Micromachines 2024, 15, x FOR PEER REVIEW 8…”

Design and Simulation of a System-in-Package Chip for Combined Navigation

“…System-in-package often faces multi-physics and multi-scale problems, which are key issues in their design and simulation [9][10][11][12]. When finite element analysis is performed on components with large size differences, such as chips, packages, and circuit boards, a large number of meshes are generated, which cause difficulty and usually require simplified and reduced-order processing; this problem, however, was not the focus of this study.…”