Finite element analysis (FEA) modelling and experimental verification to optimise flexible electronic packaging for e-textiles

Abstract

In this paper a three-dimensional model of a novel electronic package has been developed using Finite element analysis to evaluate the shear load, tensile, bending and thermal stresses. Simulations of a complete flexible flip chip electronic packaging method are performed to minimize stresses on the packaged electronic device to improve robustness and reliability. Three component under-fill adhesives (Loctite 4860, Loctite 480 and Loctite 4902) and three circuit substrate materials (Kapton, Mylar and PEEK) are compared and the optimal thickness of each is found by shear load, tensile load, bending test and thermal expansion simulations. A fixed die size of 3.5 mm 9 8 mm 9 0.53 mm has been simulated and evaluated experimentally under shear and bending load. The shear and bending experimental results show good agreement with the simulation results and verify the simulated optimal thickness of the adhesive layer. The Kapton substrate together with the Loctite 4902 adhesive were identified as the optimum in the simulation. The simulation of under-fill adhesive and substrate thickness identified an optimum configuration of a 0.045-0.052 mm thick substrate layer and a 0.042-0.045 mm thickness of the Loctite 4902 adhesive. The bending simulation has also been used to determine the neutral axis of the encapsulated electronic package in this paper, thus identifying the optimal material and thickness for the encapsulation layer of the package.

Integration and Testing of a Three-Axis Accelerometer in a Woven E-Textile Sleeve for Wearable Movement Monitoring

“…Once the circuit was etched, the components were soldered to the copper using lead free solder paste (LFS-UFP, BLT Circuits) at 230 °C for 60 s on a hot plate. An additional underfill adhesive (Loctite 4902, Henkel Adhesives) was used to improve the adhesion and peel strength of the components [ 34 ]. For the external connections, a multi-strand copper Litz wire of 350 µm total diameter was soldered to the respective pads on the strip.…”

FEM Analysis of Buckled Dielectric Thin-Film Packaging Based on 3D Direct Numerical Simulation

“…Various packaging cap materials such as metal, polymer, and Si materials can be transferred to the target device wafer by metallic or polymeric bonding techniques and debonding of the temporary carrier wafer. Because there are lots of materials associated with electronic packaging, FEM (Finite Element Method) simulations have been frequently used to find mechanical stress, strain, and reliability parameters of the electronic packages [ 8 , 9 , 10 ]. For example, FEM simulations of MEMS packaging and BCB (Benzocyclobutene) bonding have been presented with experimental verifications [ 11 , 12 ].…”