Improving the Uniformity of Cu Deposition in Fanout Panel Level Package with FEM Simulation Model

In the packaging industry, Fan-out Panel Level Packaging (FOPLP) is recognized as an advanced technology. Compared to Fan-out Wafer Level Packaging (FOWLP), FOPLP offers significant advantages, including higher production capacity and reduced costs. Within the package structure, the copper redistribution layer (RDL) serves not only as an interconnection platform but also plays a key role in influencing the electrical and mechanical performance of the system. However, as the panel size and processing area increase, stable and uniform electrical and fluidic distributions need to be controlled during the electroplating process, otherwise the thickness of the RDL will be non-uniform. The uniformity of electroplating serves as a crucial metric for assessing plating performance, with the specification for manufacturing non-uniformity ($\text{NU} \%$) defined by a stringent threshold of less than 10 %. This study utilized the finite element method (FEM) in COMSOL Multiphysics ${ }^{(8)}$ to predict and analyze the thickness trends of plating copper, thereby saving both time and money. The kinetic parameters corresponding to the electroplating solution formulation used in simulation were obtained using a potentiostat. During the electroplating process, the contact pins on the holder make contact with the seedlayer of the cathode and apply a voltage to facilitate the reduction of metal ions, resulting in the deposition of a metal layer. The external potential is a critical factor that influences the electroplating process, as it can be adjusted to control both the thickness and uniformity of the plating copper layer. The study aimed to address the issue of plating non-uniformity in Fan-out Panel Level Packaging through simulation. This is the detailed discussion on how pattern firewall design, seedlayer, and contact pin influence plating uniformity. The findings of this research can be directly applied to solve manufacturing challenges.