Failure Analysis of a MEMS Micro-Injector Printing Head

The failure mechanism of a monolithic MEMS twin-bubble micro-injector failed to eject ink smoothly has been investigated. A model that analyzes the thermal expansion mismatch among the nozzle plate, the silicon substrate, and the PPO housing is proposed to explain the failure mechanism of the MEMS micro-injector printing head. In the proposed model, the thickness of nozzle plate and the width of manifold opening are the key parameters to achieve a robust design. When the gold layer thickness of nozzle plate is increased to 20 um, the robustness of the MEMS structure is improved substantially and no more ink ejection failures related to chamber crack of thermal stress is observed.