Materials and Design of Reliable Seam-Sealable Window Lids

The increasing use of MOEMS (Micro-Optoelectromechanical Systems) in optical transmission systems, such as optical cross connects, wavelength blockers, dynamic gain equalization filters, and 1xK switches, is driving the need for MEMS packages with large optical windows for light transmission through the package. Long-term reliability of MOEMS devices is dependent on package hermeticity, typically in an inert gas, such as nitrogen or argon. Thus, window lid design, hermeticity, and reliability are key to package reliability. This talk will present the material related issues in the design and manufacture of reliable and hermetic window lids used for seamsealing MOEMS packages. The focus will be on window lids with glass soldered to metal frames. A review of the seamsealing process will be presented to determine the parameters for window lid materials selection, such as types of glass and solders. The strength of the glass is a determining factor in overcoming the thermal stresses induced during window lid solder assembly. Also, the solder is critical to prevent reflow due to package heating during the seamsealing process.