Photopatternable silicone compositions for electronics packaging applications

Development of the next generation of electronics devices is creating a need for new specialized materials, application and integration processes for building reliable yet sophisticated packaging architectures. Key physical property attributes of these new materials include flexibility, low stress, and high thermal stability. To meet these needs Dow Corning is developing a family of spin coatable photopatternable silicone materials, application processes, as well as integration know-how to assist device manufactures in building the next generation of devices enabled by silicone based material technologies. These new materials can be easily coated onto electronics substrates and have been patterned using a commercially available stepper from Ultratech Inc. Films with a thickness ranging from 6 to 50 /spl mu/m have been demonstrated with patterned features resolved to 20 /spl mu/m dimensions in 20 /spl mu/m thick films. The etched regions provide a shallow sidewall slope and smooth curved surfaces that facilitate direct on silicone metallisation. After patterning the films can be cured at low temperatures (150 to 250/spl deg/C) to provide modulus values in the range of 150 to 500 MPa. These materials are inherently hydrophobic and are based on a cure System that is acid free and delivers highly thermally stable crosslinks without the need to outgas photocatalysts or ancillary chemicals. As a result, the films show very little shrinkage during thermal cure (/spl sim/2%), do not require extended high temperature processing, and provide a very low stress (<5 MPa). Yet in spite of their low temperature cure capability these materials show excellent thermal stability and mechanical integrity when exposed to high temperatures.