Abstract
In spite of a high market share of plastic IC packaging, there are still reliability issues, especially for the effects of moisture. The mechanism between moisture and epoxy polymer is still obscure. A multi-step cross-linking approach was used to mimic the cross-linking process between the DGEBA resin and JEFFAMINE®-D230 agent. Based on the molecular dynamics method, the thermo-mechanical properties and microstructure of epoxy polymer were analyzed. In this paper, the degree of cross-linking ranged from 0% to 85.4% and the moisture concentration ranged from 0 wt.% to 12 wt.%. The hydrogen bonds were investigated in the moisture invaded epoxy polymer. Although most of the hydrogen bonds were related to water molecules, the hydrogen bonds between the inside of epoxy polymer were reduced only a little as the concentration of moisture increased. The diffusion coefficient of the water molecules was found to increase with the increase of moisture concentration. When the moisture concentration was larger than 12 wt.% or smaller than 1.6 wt.%, the diffusion coefficient was less affected by the epoxy polymer. In addition, the free volume and the thermal conductivity of the epoxy polymer were considered. It was found that the moisture could increase the thermal conductivity from 0.24 to 0.31 W/m/K, identifying a coupling relationship between moisture and thermal properties. Finally, the mechanical properties of epoxy polymer were analyzed by uniaxial tensile simulation. The COMPASS and DREIDING force fields were used during the uniaxial tensile simulation. A better result was achieved from the DREIDING force field compared with the experiment. The degree of cross-linking was positively correlated with mechanical properties. For the system with the largest degree of cross-linking of 85.4%, the Young’s modulus was 2.134 ± 0.522 GPa and the yield strength was 0.081 ± 0.01 GPa. There were both plasticizing and anti-plasticizing effects when the water molecules entered the epoxy polymer. Both the Young’s moduli and yield strength varied in a large range from 1.38 to 2.344 GPa and from 0.062 to 0.128 GPa, respectively.
Highlights
As the golden rule facilitating the progress of semiconductor industry, Moore’s Law has guided the industry’s long-term strategy, cost control, and R&D target over the past50 years
The structure and thermal-mechanical properties of the moisture-invaded epoxy polymer were studied by molecular dynamics simulation
The free free volume volume and free volumethe is depicted in Figure where to thetotal black represents decreased as the moisture concentration increased, which means more space was occuthe green lines represent the proportion of free volume to total volume
Summary
As the golden rule facilitating the progress of semiconductor industry, Moore’s Law has guided the industry’s long-term strategy, cost control, and R&D target over the past. Srebnik et al [25] used united-atom molecular dynamics to predict the thermodynamic and mechanical properties of industrial epoxy resins Their results were in agreement with the experimental measurements. The thermal-mechanical properties and structure of epoxy vary greatly due to the differences of epoxy matrix, hardener, filler, degree of cross-linking, and moisture concentration. The structure and thermal-mechanical properties of the moisture-invaded epoxy polymer were studied by molecular dynamics simulation. The thermal-mechanical properties and structures of the epoxy polymer were analyzed, including the hydrogen bonds, the free volume, the diffusion coefficient of water molecules, and the thermal conductivity coefficient. The influence of degree of cross-linking and moisture concentration on the mechanical properties of epoxy polymer was analyzed
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