Hermetic glass frit packaging in air and vacuum with localized laser joining

Abstract

Glass frit packaging is a simple and robust method used for hermetic sealing of micro-devices. Conventional glass frit packaging processes rely on furnace heating where the entire package is heated to elevated temperatures, hence restricting the use of temperature-sensitive materials inside the package and generating problems in multi-stage packaging processes. The use of a laser as an alternative heat source offers the possibility of highly localized heating where the heat-input can be restricted to the joining area only. In this paper the clear benefits of combining glass frit packaging and localized laser heating are demonstrated. Two novel laser-based glass frit packaging processes for sealing of leadless chip carrier (LCC) packages in both air and vacuum have been developed. Full hermetic seals according to MIL-STD-883G are achieved in high yield processes where the temperature in the centre of the device is kept at least 230 °C below the temperature in the joining region.