Spherical alumina (Al2O3) nanoparticles were incorporated into diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The objective of this study is to investigate the effect of water absorption on the mechanical and dielectric properties of the Al2O3/epoxy nanocomposites. The results from tensile tests indicate that the incorporation of the Al2O3 nanoparticles into the epoxy can improve the stiffness of the matrix. DMA results show that the stiffness improvement is more pronounced at the rubbery state of the matrix. The Al2O3 nanoparticles can increase the dielectric constant of the epoxy resin due to the increase in the total interfacial area. Upon water absorption, the mechanical properties of the Al2O3/epoxy nanocomposites decrease evidently, because of the damage of water on the epoxy resin. However, the ductility can be improved by the water absorption process. In addition, both dielectric constant and dielectric loss of the Al2O3/epoxy nanocomposites increases greatly after water absorption treatment.

Effect of water absorption on the mechanical and dielectric properties of nano-alumina filled epoxy nanocomposites

Growth, structure, dielectric and AC conduction properties of solution grown PVA films

Dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis (DEA) were conducted for three thermoset resin systems: bismaleimide, epoxy, and vinyl ester. The resin samples were subjected to various degrees of thermal exposure (400, 270, and 330°C for 5–150 min). Dielectric constants were measured along with the thermomechanical properties. The glass-transition temperature, modulus, and weight loss were important parameters for correlating the material property changes with the heat exposure. A linear relation was determined between the thermomechanical properties and the dielectric properties of the resins under the selected exposure conditions. Therefore, DEA can be introduced as a significant technique for evaluating thermally exposed polymer materials. Interestingly, it is a nondestructive evaluation process. In the future, it could be used for onsite health monitoring of thermally exposed polymer matrix composite structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Thermal degradation analysis of thermoset resins

We report on the effects of hydrothermal ageing on the dielectric properties of epoxy-silica composites used for microelectronic packaging. The study was carried out for samples with various degrees of curing. Epoxy compounds were subjected to moisture exposure (standard JEDEC procedures) and consecutive thermal stress (240°C). Changes in the dielectric constant and in the loss factor were measured in the 100 Hz–100 kHz frequency range. It is found that water absorption increases with curing. After ageing the dielectric constant is decreased and the loss factor increased. Cured materials have a higher resistance against hydrothermal ageing.

Combined effects of humidity and thermal stress on the dielectric properties of epoxy-silica composites

Absorption of water in epoxy adhesives containing different types of fillers was studied after immersion in distilled water and in NaCl solutions during several periods of time The amount of water uptake in the adhesives was found to increase with the concentration of water-soluble fillers incorporated in the adhesive matrix The water absorption behaviour of the adhesives investigated was found to be non-Fickian Owing to reverse osmosis, the amount of water absorbed in the adhesives decreases with the concentration of the bulk NaCl solution

Effect of fillers on the degradation of automotive epoxy adhesives in aqueous solutions

The temperature dependence of the d.c. conductivity of epoxy laminate has been studied before and after exposing the samples to moisture (relative humidity 70 to 95%) and various exhalates (HCl, HNO3, HCOOH, CH3COOH, NH3 and SO2 vapours) which are generally released by electronic packaging materials. The d.c. conductivity increases with increase of temperature. At a particular temperature the d.c. conductivity increases after exposing the samples to moisture and exhalates, the increase being more at higher exposure times. The results have been explained on the basis of Fickian adsorption of moisture and consequent dissolution of the exhalate vapours in it, which possibly increases the conductivity due to ion formation.

Effect of moisture and electronic packaging exhalates on the electrical conductivity of epoxy laminate

The dielectric behaviour of epoxy and polyester laminates has been studied before and after exposing the samples to moisture (relative humidity 60 to 95%) and various exhalates (HCl, HNO3, HCOOH, CH3COOH, NH3 and SO2 vapours) which are normally released by electronic packaging materials. A strong dielectric dispersion at room temperature is observed after exposing the samples to moisture and various exhalates. The dissipation factor also increases quite appreciably, the increase being more at higher exposure times. The results have been explained in terms of the ionic conductivity due to the dissociation of the exhalates. Recovery studies have also been made and it was found that the changes were reversible except in the case of HCOOH and CH3COOH, for epoxy and in the case of NH3 for polyester. These results indicate some chemical changes in these cases.

Dielectric behaviour of epoxy and polyester laminates in moisture and electronic packaging exhalates

The performance of some commercial P-N Junction diodes, some ceramic capacitors and some resistors has been tested under moisture (RH 60% to 95%) and various exhalate vapours (HCl, HNO3., HCOOH, CH3 COOH, NH3 and SO2) which are generally released by the electronic packaging materials. The ideality factor of the diode changes after exposure, the change being more at higher exposure times. The organic acid vapours degrade the devices the most. Silicon diodes, in general, are found to be less sensitive to the humidity and exhalate vapours as compared to Germanium and Indium Antimonide diodes. The presence of oxide layer on the surface of silicon diodes may be responsible for the smaller degradation effect.

D. B. Singh

Papers

Effect of moisture and electronic packaging exhalates on the electrical conductivity of epoxy laminate

Dielectric behaviour of epoxy and polyester laminates in moisture and electronic packaging exhalates

Effect of Humidity and Electronic Packaging Exhalates on the Performance of some Active and Passive Components used in an Electronic Equipment