Title :
Parametric finite element analysis of solder joint reliability of flip chip on board
Author_Institution :
Assembly Technol. Dev., Intel Technol. Sdn. Bhd., Penang
Abstract :
Numerous studies have indicated that by encapsulating the solder joint with underfill material, the reliability of flip chip on board (FCOB) assemblies can be effectively enhanced. Typical manufacturing processes for FCOB assembly with underfill, however, involve long throughput time and additional equipment sets which are undesirable for high volume manufacturing environments. Hence, design/process simplifications, if not total elimination of underfill from conventional FCOB assemblies, that can directly result in productivity gain should be considered. A comprehensive parametric finite element analysis has been conducted to assess the feasibility of FCOB structures with partial underfill (i.e. only the peripheral joints are encapsulated with underfill material). The effects of some critical design parameters such as die size, joint height, joint diameter, joint pitch, printed circuit board (PCB) thickness and material properties of underfill on the solder joint reliability of FCOB structures were investigated in this study. Two-dimensional nonlinear plane strain finite element models of FCOB packages are employed. Moire and IR Fizeau interferometry techniques are used to measure the thermal deformation of the FCOB for model validation. Elasto-plastic deformation behaviours of solder were simulated under thermal cyclic loading from -55°C to 125°C. Maximum effective elastic and plastic strains of the solder joint were calculated and used as the indicator for determination of the solder joint reliability
Keywords :
assembling; chip-on-board packaging; elastic deformation; encapsulation; finite element analysis; flip-chip devices; integrated circuit modelling; integrated circuit packaging; light interferometry; moire fringes; plastic deformation; soldering; thermal stresses; -55 to 125 C; 2D nonlinear plane strain finite element models; FCOB assemblies; FCOB assembly; FCOB packages; FCOB structures; IR Fizeau interferometry; PCB thickness; design parameters; design simplification; die size; elasto-plastic deformation; encapsulation; equipment sets; flip chip on board; flip chip on board assemblies; manufacturing processes; material properties; maximum effective elastic strain; maximum effective plastic strain; model validation; moire interferometry; parametric finite element analysis; partial underfill; peripheral joint encapsulation; process simplification; productivity gain; reliability; solder joint; solder joint diameter; solder joint height; solder joint pitch; solder joint reliability; thermal cyclic loading; thermal deformation; throughput time; underfill; underfill material; volume manufacturing; Assembly; Capacitive sensors; Deformable models; Finite element methods; Flip chip; Joining materials; Manufacturing processes; Materials reliability; Soldering; Throughput;
Conference_Titel :
Electronics Packaging Technology Conference, 1998. Proceedings of 2nd
Print_ISBN :
0-7803-5141-X
DOI :
10.1109/EPTC.1998.755979
