Low internal temperature technique for hermetic sealing of microelectronic enclosures

摘要

A technique for enclosing microelectronic circuit elements in hermetically sealed packages comprising a planar ceramic substrate with a box-like ceramic cover sealed thereto by a fused glass coating. The glass sealant is applied to the substrate in the form of a paste which thereafter is fired at high temperature and cooled to produce a smooth glass coating. With the cover in place on the substrate, the glass coating is remelted by heat developed by infra-red radiation developed by four line-focussed radiant heaters at the four sides of the package. The radiation of each heater is focussed at the interface line between the cover and the substrate. Because the radiant heat is concentrated along the interface line, unwanted heat transfer into the package is minimized, and the temperature is prevented from rising sufficiently to damage heat- sensitive elements. Upon removal of the radiant heat, the glass hardens in a condition of fusion and/or chemical bonding with the cover and substrate providing true hermetic sealing.