PBO PI：Polyimides (PI) & Polybenzoxazoles (PBO)

Fan-Out Wafer Level Packaging Process Flow ( Source - Yole Development)

Polyimide (PI) and Polybenzoxazole (PBO) products are typically used as a stress relief and protective insulating layer before packaging or redistribution layer (RDL).

PI and PBO plays a critical role in advanced microelectronic packaging as an insulating material and can be processed as a standard photolithography process. Conventionally, photoresist was used on top of the PI/PBO polymer to develop the etching pattern, but to simplify the manufacturing process & cost, photosensitive PI/PBO polymer were developed later on. These polymers possess several outstanding features such as high thermal stability, chemical resistance, low flammability & low dielectric constant for the use in advanced packaging technology. Relatively, PBO’s has lower dielectric constant and lower moisture absorption due to the absence of carbonyl group in their polymer backbone.

Chemical structure of PBO & PI ...