Micro lens array assembly for optical organic substrate
A polymer lens attach process is developed on Optical Multi-Chip Modules (OMCM) with integrated optical waveguides and tested successfully in Deep Thermal Cycle (DTC) at -40°C/125°C for 1000 cycles. The lens attach is completed in a two step process: UV tack of the lens array using a high precision pick and place tool followed by the dispense of a viscous sidefill material along the lens array's periphery to mechanically secure it to the OMCM laminate. A screening protocol is developed based on manufacturing and reliability criteria for testing lens array UV tacking and sidefill adhesives. Manufacturing selection criteria include good adhesion and low infiltration in small gaps. Low infiltration under the lens array is necessary to prevent contamination of laminate optical features. For testing lens attach reliability, a list of critical process parameters are chosen including silicone and epoxy UV tacking and sidefill adhesives with a wide range of thermo-mechanical properties: Young's Modulus (E), Coefficient of Thermal expansion (CTE), glass transition temperature (Tg). Lens attach reliability performance is assessed by both visual inspection for mechanical integrity failures, and using lens to lens insertion loss optical test read-outs.