A new thermally stable polyimide film for advanced microelectronics packaging

One of the key issues for semiconductor chip packaging in. microelectronics technology is the reliability of the,chip packaging during harsh temperature change in practical use. Typically, a thermal expansion mismatch between a silicon chip and a package substrate causes cracks between interconnecting bumps after the thermal cycling when the wiring pitch becomes fine. To overcome this problem, we have developed a new dielectric film which has extremely. low CTE (Coefficient of Thermal Expansion) with the almost equal value to silicon over a wide range of temperature. The film will realize thermally-reliable interconnection at package substrate fabrication and in high temperature applications.