Thermal and Chemical Stability of a Spin-Coated Epoxy Adhesive for the Fabrication of a Polymer Optical Waveguide

Abstract

Spin coating is a common method for depositing very thin polymeric film across a planar surface in a short period of time. Thinning occurs due to the combined effects of centrifugal spin-off and evaporation. The evaporation of any reactive component during spinning plays an important role on the stability of spin-coated polymeric film. An investigation was carried out to study the effects of spinning on the thermal and chemical stability of the epoxy adhesive. The thermal stability of both spin-coated and without spin-coated epoxy adhesive was measured by thermogravimetric analysis (TGA) at heating rate of 10 °C/min in an inert environment. A lower thermal stability was observed for the spin-coated epoxy adhesive. At the center of the substrate it is more stable than the other locations. Thermal stability greatly deviates at the border side of the spin-coated substrate. Higher chemical stability was also observed at the center than the other locations of the spin-coated layer when immersed in the metal (nickel) etchant chemical solution. The lower thermal and chemical stability is mainly due to changes in the material properties during the spinning process. From this study it is proposed to use the reactive components that are less volatile, having higher intermolecular forces, and allow a greater part of the thinning behavior to occur without significant changes in the fluid properties during the spinning process. Lower spin speed also suggested to reduce the mechanical degradation of the polymeric adhesive for the fabrication of a polymer optical waveguide.

Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR

“…Critical properties such as the chemical resistance, 12 corrosion resistance 13,14,15 thermal stability 16,17 and mechanical strength 18 offered by these materials are well known to depend on the network structure of the supporting resin. A highly desirable goal in formulation is therefore the controlled synthesis of well-defined network structures, yet the macromolecular architecture underpinning the performance of these materials remains largely unresolved.…”

Adhesive technology for photonics

“…Therefore, there is a major need for practical as well as scientific information about the proper handling and properties of polymeric materials for the fabrication of reliable photonics products. Recent studies 38,43,53 have focused mainly on proper polymer processing and the fabrication of reliable photonics devices. The challenges are to achieve compatibility with other electro-optic systems and processes, end-use reliability, reproducibility, stability, acceptable performance, and cost, commensurate with added value.…”

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

“…at 120°C) curing on a hot plate. 5 Heat Exposure of the Cured Adhesive Film Figure 3 shows the overview of a typical photolithography process for the fabrication of an inverted rib polymeric optical waveguide using benzocyclobutane (BCB) as the core and epoxy as cladding material. In this application, after deposition of the initial cladding layer, an additional heating step is required in subsequent steps for fabrication of waveguide devices.…”

“…Therefore, the polymeric material should be sufficiently reliable to withstand typical fabrication processing and operation conditions with good performances. 5 To evaluate the reliability of the spin-coated lower cladding layer of such a polymeric optical waveguide, the cured and deposited thin adhesive film in the untreated substrate (sample 2) was subjected to heat-resistance testing. To take into account curing of the subsequent BCB core layer at high temperature, testing was carried out at 250°C for 30 min.…”