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Carboxylic functional groups were introduced on multi-walled carbon nanotubes (MWCNTs) using the Ultraviolet (UV) Ozone treatment. Three melt spinning process parameters (spinning temperature, spinning distance, and the number of spinning revolutions) were evaluated by robust design (Taguchi’s method) for a composite of fibers with the objective of enhancing the mechanical strength. The optimized melt spinning parameters were obtained. The predicted strength value of CNTs–PE fibers was determined using statistical analysis, and this value is close to the verification experiment value. Thus, robust design was successfully applied in this study. The crystallization of bulk pure PE was significantly increased by the formation of fibers through mechanical drawing of the melt spinning. The addition of CNTs in the polymer matrix accelerates the nucleation and crystal growth of the polymer. No CNT alignment in the PE matrix was observed on the sectioned surface of the fiber using Scanning Electron Microscopy (SEM). The degree of crystallization of the PE polymer plays an important role in the mechanical strength enhancement.

Excessive heat and temperature gradient may introduce failures in the components, such as cracking, delamination and warpage, eventually causing device failure. While there has been significant research toward understanding the thermal performance of many different electronic packages, the majority of these studies do not take into account the combined effects of thermal and mechanical interactions. This paper evaluates the thermal performance of flip chip packages based on the couple-field elements available in a numerical code, ANSYS, to study the interactions between temperature and stresses generated during the manufacturing process, where both two dimensional (2D) plane strain and three dimensional (3D) models of the flip chip package are considered. Compared with the model assuming uniform temperature distribution over the entire package, the model with temperature gradient provided more accurate stress profiles in the solder interconnections and underfill fillet. Further finite element studies based on the 2D model are conducted to evaluate the effects of thermal conductivity and substrate board configuration on the overall temperature and stress distribution in the package.

The reliability and mechanical performance of electronic integrated circuit (IC) package is studied based on the finite element analysis. The flip chip on board (FCOB) package – one of the most current plastic encapsulated IC packages – consists of a die, solders, a printed circuit board and underfill resin encapsulated between the die and PCB, which is subjected to a typical thermal cycle experienced during the manufacturing process. The effects of viscoelastic properties of underfill resin on mechanical responses and residual stresses of FCOB packages are specifically studied and the results are compared with those obtained for a thermoelastic underfill resin. The viscoelastic properties of underfill resin are characterized using the time–temperature superposition (TTS) technique. Both the rigid and flexible PCB substrates are considered. It is found that the elastic model underestimates significantly both the thermal stress and the strain level in the solder joints, whereas it overestimates the stress concentrations in the underfill fillet around the die corner than the viscoelastic model. When the package is subjected to an extended dwell time at an elevated temperature, a moderate loss of mechanical coupling between the die and organic substrate is expected due to the relaxation of underfill resin. The implication is that the viscoelastic nature of underfill material should be properly taken into account if the failure of solder joints and the lifetime of the package are to be accurately estimated.

A gyroscope-free inertial measurement unit (GF-IMU) uses only accelerometers to compute specific force and angular rate. It is a low-cost inertial system, but its measurement error diverges at a rate that is an order faster than that of a conventional inertial system equipped with gyroscopes. In this paper, a redundant accelerometer-aided gyroscope-free IMU is designed to achieve a stable and bounded system. In this system, a three-axis accelerometer is used in addition to a set of six accelerometers that is typical in a conventional gyroscope-free IMU. The linear error dynamics of this aided gyroscope-free IMU is derived, and the effects of accelerometer errors are analyzed.

A numerical analysis was conducted for the resin film infusion (RFI) process using semi-cured thermosetting resin films. Mathematical models were developed for the compression of fiber and the viscosity of resin. The force balance between the fiber preform and the resin was considered to account for the deformation of fiber preform and the swell of fiber during the infusion. In an effort to locate the optimal process conditions such as the mold temperature, the fiber volume fraction, and the infusion pressure, a parametric study was carried out for the progression of resin and the infusion time for different process conditions. The numerical code developed in this study was found to be useful in determining the maximum height of vertical sections that can be infused by squeezing the liquefied resin film from the base panel.