No abstract

The Lead-Free (LF) and Halogen-Free (HF) "green" initiatives are driving the advanced packaging manufacturers to develop new generation materials and assembly technologies. However, the moisture related reliability issues become the significant technical challenge to meet stringent reliability and quality standards comparing to the previous Lead and Halogen technology. In this study, the moisture absorption and desorption performance of Halogen Free and Lead Free material were investigated. The experimental data revealed that after fully baked process there was still some resident moisture which was mainly contained at substrate level. The modeling data of moisture absorption and desorption behavior with 125°C bake comparison was discussed and was fully aligned with experimental data. Moreover, a 'soft bake' method via Nitrogen and dry air was introduced. In low RH effect test, under 25°C / 60%RH precondition process, all the moisture absorbed for 1100 hours can be removed by 'soft' bake. This indicates that not only no moisture absorption in low RH environment, but also an additional 'soft bake' process occurring during the storage time. The results demonstrated that the storage of moisturesensitive material in the optimized environment is an attractive facility solution which can reduce the risk of popcorn and cracking problems.

Nanocrystalline diamond (NCD) films were synthesized by hot-filament chemical vapor deposition (HFCVD) method at different temperatures (600 °C, 620°C, 640°C and 660°C). The AFM and Raman analyses demonstrated that deposition temperature has a great effect on the surface roughness and quality of NCD films and 620°C is the temperature to grow NCD films with smooth surfaces.

A newly developed nano/microcrystalline diamond composite film for thermal applications was prepared in this investigation. A microcrystalline diamond (MCD) film was deposited onto silicon substrate by hot filament chemical vapor deposition (HFCVD) method, and then a nanocrystalline diamond (NCD) film was grown onto this MCD film to obtain a NCD/MCD composite film. The root-mean-square (RMS) value of surface roughness for the composite film estimated from the atomic force microscope image was 42.7nm. Compared with 85.9nm for the MCD film. And it was also found that the thermal diffusivity increased from 32.61mm2/s to 37.63mm2/s by further growing a NCD film. Results indicated that the deposition of NCD film reduced the rough surface of the MCD film with grain sizes of the order of microns, and thus increased the efficiency of diamond films as thermal spreading device. It was found that the NCD/MCD composite film had a smoother surface and a higher thermal diffusivity compared with MCD film.