Lattice Boltzmann Method of Different BGA Orientations on I-Type Dispensing Method

Abstract

This paper studies the three dimensional (3D) simulation of fluid flows through the ball grid array (BGA) to replicate the real underfill encapsulation process. The effect of different solder bump arrangements of BGA on the flow front, pressure and velocity of the fluid is investigated. The flow front, pressure and velocity for different time intervals are determined and analyzed for potential problems relating to solder bump damage. The simulation results from Lattice Boltzmann Method (LBM) code will be validated with experimental findings as well as the conventional Finite Volume Method (FVM) code to ensure highly accurate simulation setup. Based on the findings, good agreement can be seen between LBM and FVM simulations as well as the experimental observations. It was shown that only LBM is capable of capturing the micro-voids formation. This study also shows an increasing trend in fluid filling time for BGA with perimeter, middle empty and full orientations. The perimeter orientation has a higher pressure fluid at the middle region of BGA surface compared to middle empty and full orientation. This research would shed new light for a highly accurate simulation of encapsulation process using LBM and help to further increase the reliability of the package produced.

Effect of hourglass shape solder joints on underfill encapsulation process: numerical and experimental studies

“…In a separate study, LBM simulation of capillary underfill was compared with results obtained using FVM. Results from the LBM simulation showed finer details compared to those from FVM simulation, allowing for the formation of voids to be shown within the simulation (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016c. LBM outshines finite volume in terms of its simplicity of formulation and its capability to capture finer details due to its particle nature.…”

“…Ball grid arrays (BGA), being a type of SMT, use small solder balls to form connections between the electronic components and the PCB. BGA technology outshines other SMT counterparts like pin grid array (PGA), as it allows for higher interconnection density, better performance due to shorter leads, and better heat conduction (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016cGan et al, 2019).…”

“…A smaller gap height between the chip and substrate will lead to longer filling times (Khor et al, 2012), larger pitch size on the bump array reduces the filling time (Yao et al, 2014), and with the solder bump arrangement, a perimeter array is reported to have faster filling flow compared to the middle-empty and full arrays (Khor et al, 2010;Abas et al, 2016aAbas et al, , 2016bAbas et al, , 2016c. Additionally, a Ushaped dispensing method has achieved the shortest filling time compared to I-shaped and L-shaped methods (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016c. A force-induced process such as pressurized underfill is also reported to have a faster filling time compared to the conventional capillary method (Gan et al, 2019).…”

“…LBM's best feature, compared to other approaches, is its ability to take into account the microscopic particle to particle interaction forces (Gan et al, 2019). Although simulation results obtained from finite volume method (FVM) simulations are in close agreement with experimental results in most cases, visualization details like void formation cannot be accurately predicted due to the complicated particle interactions that occur during underfill flow (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016c. The use of LBM, which belongs to the particle-based methods, in the field of electronic packaging represents a possible solution to this problem.…”

Investigation of Nano-Reinforced Lead-Free Solder During Reflow Soldering-A Molecular Dynamic Approach

“…This approaches also demonstrating the reaction of the solder in a particular condition, clearly and accurately. Over the years, there are lots of numerical approaches used to simulate the reflow soldering process, including Finite Element Method (FEM) [26], Finite Volume Method (FVM) [27], Lattice Boltzmann Method (LBM) [28], Discrete Phase Method (DPM) [29] and Molecular Dynamics (MD) [30].…”