Effect of spin coating on the curing rate of epoxy adhesive for the fabrication of a polymer optical waveguide

Abstract

Spin coating is a simple process for rapidly depositing thin, solid polymeric films onto relatively flat substrates. Evaporation occurs during spinning of the relatively volatile species in any solution. The curing behavior of spin-coated polymeric film is influenced by the evaporation of any reactive component. An investigation was carried out on a silicon substrate to study the effects of spin coating on the curing behavior of the epoxy adhesive. The degree of curing for both spin and without spin-coated epoxy adhesive was measured by Fourier-transform infrared spectroscopy (FTIR). A slower curing reaction rate was observed for the spin-coated epoxy adhesive. The composition gradient established by solvent evaporation during spinning is responsible for the slower curing reaction rate of the spin-coated epoxy adhesive. From this study, it is proposed to use solvents that are less volatile and allow a greater part of the thinning behavior to occur without significant changes in the fluid properties during the spinning process.

Interfacial adhesion of spin-coated thin adhesive film on silicon substrate for the fabrication of polymer optical waveguide

“…The slower reaction rate is due mainly to the material properties changing during spinning. 3 In another study, the lower thermal and chemical stabilities for spin-coated adhesive were also observed due to rapid fluid flow and convectively driven evaporation that occur during spinning. It was also lower at the border side of the spincoated polymer layer due to the spinning force experienced there being highest, the greater number of voids, and the low cross-link density.…”

“…Throughout this investigation, 2 cm 3 2 cm square edge silicon wafers were used to avoid the radial nonsymmetry in rectangular substrates that causes larger corner build-up effects on spincoated polymer films. 3 After standard cleaning, sample types 3-5 were plasma-etched with sulfur hexafluoride (SF 6 ) and the oxygen mixture (SF 6 1 O 2 ) of process gas. The etching was done in a reactive ion-etching plasma chamber (PlasmaTherm 790 Series).…”

“…Cross-linked polymer chains are also chemically bound together to give a three-dimensional ''chicken wire'' molecular structure or chemical network. 3 The higher the curing degree, the stronger the chemical bonding and the better adhesion strength at the adhesive interface. Because the curing degree and stability of adhesive are higher at the center and lower at the border side, 3,5 consequently, the adhesion strength is also higher at the center and lower at the border side of the spincoated adhesive.…”

“…2 Due to the complexity of common spin coating solutions, the behavior of mixed solutions should be understood for the conditions of rapid fluid flow and convectively driven evaporation that occur during spin coating. 3 The critical issues of spin-coated adhesives in these applications are film thickness and adhesion strength. Many studies have been directed to predict the final film thickness, but no attempt has been paid to the interfacial adhesion induced by the spinning process.…”

Investigation of the optical properties of ZnO/epoxy resin nanocomposite: Application in the LED

“…Volatile solvent evaporates during spinning in any solution. It is the most common technique of coating thin films onto wafers because of that it makes uniform films with well-controlled thickness [20].…”