Multi-physics Domain Optimization Design For 28nm IC Package System

As the demand of micro-electronic package system for package miniaturization, high performance and multi-function, the corresponding thermo-mechanical reliability, thermal and electrical performance related issues are become more and more serious. Moreover, thermo-mechanical reliability, thermal and electrical performance of micro-electronic package system are easily affected by external environmental factors simultaneously, showing obvious multi-physics characteristic. Therefore, the research on multi-physics optimization design is widely carried out and becomes the hotspot and difficulty in the micro-electronic package industry.n this thesis, thermo-mechanical reliability, thermal and electrical performance of FCCSP(Flip Chip-Chip Scale Package) based on advanced 28 nm Si process technology are investigated by using numerical simulation method. Moreover, multi-physics co-design and simulation is carried out. Simulation analysis technology is actually applied into each stages of product design, helping to promote designing ability, product performance and reliability. The main contents and results are as follows.(1) Based on thermo-mechanical reliability simulation platform ANSYS Workbench, warpage and stress study of FCCSP package is carried out by finite element method. The influences of structural geometries and material properties are evaluated, including molding compound thickness, die thickness, substrate thickness and molding compound type. Results indicate that different packaging solutions show obvious different package warpage but little difference of die stress. Optimization design of packaging solution,to minimize the package warpage and die stress, effectively improve the thermo-mechanical reliability.(2) Thermal simulation software Flotherm based on computational fluid dynamics(CFD) is employed to investigate heat dissipation and thermal performance of FCCSP package. Junction temperature and thermal resistance are calculated. The influences of package size, die size, substrate inner copper layer thickness, the thermal conductivity of substrate BT material and substrate solder mask opening size on package level thermal performance are analyzed. Moreover, the effects of heat sink fin number along PCB direction and molding compound direction respectively on system level thermal performance are analyzed. The proper fin number and layout of heat sink is obtained. By simulation analysis, thermal performance design of FCCSP package is optimized, and a best thermal solution of package level and system level are reached.(3) Based on frequency-domain method,signal integrity and power integrity studies of FCCSP package were done using ANSYS electrical simulation platform. The influences of passive channels to the quality of signals are also studied,combined with the signal integrity modeling research. According to the simulation results,reliability,IR-drop and current density issues could be solved by increasing the power plane area.