Effect of coupling agents on thermal, flow, and adhesion properties of epoxy/silica compounds for capillary underfill applications

In this study, the different silane coupling agents were added to epoxy/silica systems. The effects of the type of silane coupling agent in the epoxy/silica compounds on the thermal, flow and adhesion properties were investigated. The curing behavior was examined by differential scanning calorimetry (DSC), and the flow properties of the epoxy compounds were evaluated from penetration rate measurements. The adhesion strength as a mechanical property was determined by die shear strength testing. The silane coupling agent type had a significant effect on the thermal, flow and adhesion properties. The coefficients of thermal expansion (CTE) and adhesion of the DGEBF epoxy/SiO2 systems could be enhanced by the addition of silane coupling agents. In addition, the penetration rate was increased by the addition of a coupling agent except for the CA-A coupling agent. This was interpreted in terms of the reactive functional groups and dispersion forces resulting in coupling agents on the interfaces between the DGEBF epoxy resin and silica.

Penetration rate of CA-M coupling agent was higher than that of other coupling agent. High penetration rate of CA-M coupling agent was due to the relatively strongly repulsive force of the CA-M in DGEBF/SiO2, which is due to the hydrogen groups of the CA-M in dispersion phases with the DGEBF.Figure optionsDownload as PowerPoint slideHighlights
► Improvement of dispersion force for epoxy/silica compounds as a capillary underfill.
► Selection of coupling agent for excellent thermal, flow, and adhesion properties.
► Repulsive force of coupling agent has an effect on penetration rate and shear strength.
► Reactive groups in coupling agent lead to bad flow properties in capillary underfill.