Electronic Packaging: Sealing ☆

This article discusses the applications of hermetic seal in electronic packages to prevent the interference of contaminants into the package. A sealed package is hermetic if it fulfills the leak rate specifications as stipulated in MIL-STD-883C. The sealing methods depend on the types of packages (metal or ceramic). Metal packages can be sealed by welding or soldering. Solder sealing may be accomplished by hand, heated platen or furnace; while parallel seam welding and one-shot welding are among the welding techniques for metal packages. Solder sealing is the most common method to seal ceramic packages. Refractory metal/alloy and glass are melted onto the ceramic surface to form hermetic sealing. In addition, a typical parallel seam welding apparatus is presented. Finally, a case study revealed that shorting may occur if a hermetically sealed package contains impurities in its circuit.