Characterisation and modification of optoelectronic substrate surfaces for enhanced adhesive flow control

Optoelectronics manufacturers are under continuous pressure for miniaturisation of optoelectronic modules. One route to further miniaturisation is to reduce the spacing between the optical and optoelectronic components in the optical path adhesively mounted to ceramic carriers. Flow control of the adhesives over the ceramic surface is then imperative. Uncontrolled wetting can lead to an excessive adhesive footprint which interferes in the application of other adhesives for subsequent components. However, insufficient wetting can lead to low strength bonds vulnerable to thermal fatigue and shear failure. The goal of the work was to minimise the potential for uncontrolled wetting while maintaining unmodified bond properties. In addition positional stability of adhered parts on cure and in-service must not be detrimentally affected. [Continues.]