Application and evaluation of AL-X polymer dielectric for flip chip and wafer level package bumping

In this paper we present the results of a study done to compare and contrast BCB and ALX polymers in typical WLP structures fabricated at RTI. Based on initial studies of the materials vendor, Asahi Glass Corp, AGC, we have examined the processing parameter space of ALX-211, in order to develop scalable manufacturing processes for these films. We present process flow and photo property data on ALX-211, including spin speed curves and resolution plots. We also present data on the planarization capability of AL polymer, the adhesion of ALX-211 to metals and inorganic dielectric materials as evaluated using polymer bump shear structures. We have incorporated the ALX-211 polymer into a typical bump-on-polymer process flow, with eutectic Sn/Pb solder bumps, to compare its performance to that of BCB through solder bump shear testing.