Kazuhiro Ikemura

Solid type cavity fill and under fill materials for new IC packaging applications

IC packaging methods are diversified drastically today, because of the requirement for the package to perform the IC characteristics itself. The majority of encapsulating material in the IC packaging market is transfer molding. However, the transfer molding method is hard to apply to some new applications such as flip chip, cavity fill type PPGA (plastic pin grid arrays), BGA (ball grid arrays), and tape carrier packages. Liquid type resins are mainly used for these new applications in the current market. However, there are several serious disadvantages to using liquid type resins. The problems are poor processability and reliability. Under these circumstances, we focused on the improvement of the two disadvantages for liquid resin applications on flip chip and cavity fill type PPGA and BGA. Our newly developed materials are solid compounds at room temperature. These compounds are designed based on the study of reliability and processability. The base resin systems are selected by moisture performance and fluidity characteristics.

Multi layer film adhesive for IC packaging applications

The adhesives have important functions in the recent IC packaging. The packages are more complex because of the trend of IC integration. For example, high thermal conductive adhesives are used for high power ULSIs. Stress insulating adhesives are used between two materials which have big difference in thermal expansion coefficient such as between metal heat sink and ceramics. From the general technical standpoint, in almost all cases, thermal conductivity and stress insulation are trade-off factors. Additionally, the adhesion strength and processability are also discussed as important functions. To develop materials which have high performance such as stress insulation with good thermal conductivity, multi layer functional film adhesives have been studied. The multilayer structure has made it possible to get high thermal conductive and low stress characteristics simultaneously with high adhesion.

Improving Releasability of Mold Materials for IC Encapsulation Using Epoxy Compounds

The effect of dopants such as zirconium and nitrogen on the releasability of Y2O3-based ceramics from molds was investigated for integrated circuit packaging using epoxy molding compounds (EMCs). Co-doping of these elements was carried out by annealing the surfaces of 5mol% ZrO2-Y2O3 samples under a N2 flow at 1100-1300 °C, resulting in concentration of nitrogen near the surfaces of the samples. The adhesion strength was minimized by exposure at about 1200-1250 °C, which was less than half the value for the undoped Y2O3. The co-doping remarkably decreased the polar part of the surface energy and consequently hydrophobicity of the ceramic surfaces increased. The excellent releasability characteristics were likely related to the depression of dissociative adsorption of water molecules, which are considered to act as active sites for the adhesion of EMCs.