Simulation Methodologies for Acoustic Noise Induced by Multilayer Ceramic Capacitors of Power Distribution Network in Mobile Systems

In this article, multilayer ceramic capacitors (MLCCs) induced acoustic noise is studied through simulation investigation of the vibration behavior of the printed circuit board (PCB). The board vibration theory is briefly summarized to understand the key parameters influencing intrinsic board vibration properties. The identified key parameters are the thickness, mass density, and Young's modulus of each board layer. To accommodate the parameter variations in real board fabrication process, a statistical simulation model for PCB vibration modal response is proposed. The simulation results have shown good correlation with the measurement. The sensitivity analysis of board vibration properties to the identified parameters of each layer has also been conducted through simulation. Based on the derived intrinsic board vibration properties, the PCB vibration behavior with capacitor as forced excitation is further analyzed through modal superposition. The simulated results also exhibit good correlation with measurement. With the proposed simulation methods, engineers can evaluate the board vibration behavior at early design stage and some design guidelines for placing MLCCs can be derived to reduce acoustic noise.