Why LSR Is A Leading Material For Optical Micro Molding

In the realm of optical micro molding, Liquid Silicone Rubber (LSR) is emerging as a transformative material—offering a unique balance of optical clarity, durability, and design freedom. While thermoplastics like PMMA, COP, and polycarbonate have long dominated optical manufacturing, LSR’s thermal endurance, geometric flexibility, and mechanical resilience position it as an advanced alternative for demanding environments and intricate component designs.

Unlike thermoplastics, LSR is a thermoset elastomer that cures through a cross-linking process, allowing molding at lower injection pressures and gentler processing conditions—critical advantages when working with micron-scale geometries. This makes LSR particularly valuable for preserving delicate mold features while ensuring consistent optical quality. According to Jake Steinbrecher, Senior TS&D Scientist at DOW Performance Silicones, “Optical LSR is unique in that it can withstand a wide range of environmental conditions in which traditional optical plastics may struggle. Think UV, high temp, etc.”

Post-molding, LSR optics deliver exceptional transparency and toughness, making them ideal for sectors like wearable medtech and automotive sensing—applications where reliability under heat, UV exposure, or mechanical stress is essential. Furthermore, LSR’s elasticity enables molding of complex optical geometries, including undercuts and abrupt thickness transitions, that are difficult or impossible with rigid plastics.

As Steinbrecher notes, “LSR should help engineers think outside the box.” Its low viscosity, thermal stability, and tunable mechanical properties are driving innovation in optical and hybrid optical-mechanical components—heralding a new era of micro-molded optics that combine performance, resilience, and design freedom.