Report on Molecular Structures of Buried Interface of New Packaging Materials
Research Report Highlight
Plasma treatment effects on polymer surfaces in flip-chip processes were studied, as well as buried polymer/epoxy interfaces and the correlation of adhesion strength to molecular disorder – the more disorder, the higher the adhesion strength.
In this document we will report on our current progress on the project titled Nonlinear Optical Spectroscopic and Imaging Studies on Surfaces and Buried Interfaces in Packaging in Situ. We selectively probed buried interfaces and looked at plasma effects with a cover. We have focused on two polymers, PS and PI (PMDA-ODA), and looked at a BADGE type commercial epoxy to serve as a model underfill material. We have utilized various plasmas and determined what effect they can have on polymer surfaces and how this affects the buried polymer/epoxy interface. We have also investigated real flip-chip devices, provided by Texas Instruments (TI). The nonlinear optical technique sum frequency generation (SFG) spectroscopy was the primary method of investigation and it was supplemented with FT-IR and lap shear analysis. SFG gives information on the surface or buried interface, FT-IR shows the bulk structure, and lap shear analysis yields mechanical properties. Three projects will be outlined in this report: 1. Cover effect, for plasma, to simulate plasma treating conditions in industry; 2. Molecular level study of plasma-induced adhesion promotion, the interface of polymer with and without plasma is very different and this leads to different adhesion strength; 3. Apply developed methodology to probe TI samples, by milling down we can look at the buried interface, this is a new project but it is working and we will have complete results soon.