A negative working photosensitive polyimide (PSPI) for use as a semiconductor surface coating material has been developed.This material has been widely used as a buffer coating to protect electrical circuitry on IC chips in the semiconductor market.We have now developed a new negative working photosensitive polynorbornene (PSPNB) for Wafer Level Packaging (WLP).These cured PSPNB films have very low water absorption and low dielectric constant in addition to high adhesion to a wide range of substrates including SiO2,etc.The polymer has attractive processing properties,such as a low cure temperature,excellent dielectric properties,and desirable mechanical properties,most notably,low residual stress after cure.A discussion of the polymer properties,processing conditions and the results of the adhesion to a wide range of substrates will be presented.
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