Novel Low Df Thermosetting Film and Photo Imageable Film

Abstract

There are various demands for interlayer insulation film. One typical demand is to interlayer insulation film with low Df for substrate to decrease transmission loss, and another typical demand is to low warpage, fine via type photo imageable interlayer insulation film for RDL. We have developed two types of the novel interlayer insulation films, one was low Dk/Df thermosetting film and another was fine via type photo imageable film. Epoxy based interlayer insulation film, which was mainly used for substrate, showed high transmission loss at mm wavelength due to its high Df, especially at high temperature. But it showed good processability and reliability due to its thermosetting property. PPE was known as low Df resin, but it had poor processability and reliability due to its thermoplastic property. Thus we have synthesized the novel curable PPE resin, and by using the resin, we have developed the novel thermosetting PPE based interlayer insulation film for substrate. It showed far lower Df and far lower transmission loss compared to the low Df type epoxy based interlayer insulation film. We have developed the novel photo imageable interlayer insulation film for RDL. Ordinally photo imageable PI solution was used for RDL, but it showed high CTE, which caused warpage and reliability issue, high surface roughness, which required post processing process, and high curing temperature. We have used the novel epoxy acrylate and developed the novel photo imageable film, which showed low CTE, low surface roughness and low curing temperature.