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Since the array of wafer-level packages formed by bonding of a cap wafer to a substrate wafer, how to well encapsulate the intricate sensor devices in wafer-level is the critical issue in the development of image sensor products. This paper presents an analytical model for design and fabrication of wafer-level adhesive bonding. A novel mechanical approach is proposed, which considers each layer in bonded wafer as a beam-type plate with effective material properties. Based on this mathematical modeling, the wafer warpage under thermal loading is predicted and compared to the experimental measurements. It is shown that our newly developed wafer warpage modeling offers simple and precise evaluation of wafer-level adhesive bonding process.

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This paper presents a failure analysis result for enhancing the reliability of thermal inkjet printhead. A novel inkjet printhead is fabricated using MEMS process, and we analyze the failure mechanism of inkjet head based on detailed experimental observations. The design modification of micro heater to avoid an early stage of failure yields the reliability enhancement of printhead.

This work presents an experimental study to analyze the performance of thermal actuators to generate bubble. The heaters are debigned to have different current density distributions based on numerical analysis. The bubbles generated by heaters are compared to each other by visualization techniques. It is shown that the geometries and driving conditions of heater strongly affect the bubble behaviors. The geometries like arc or trapezoid-shape induce the non-uniform current densities and therefore change the driving conditions for generating bubbles. The experimental result reveals that the proper considerations on heater geometry are required to use the heater as a thermal actuator.