Projection welding of TO style packages is a resistance welding process used to join a cap (cover) and stem (package). A local extension (projection) is provided to concentrate the power and heat. The collapse of the projection and increase in bulk resistance leads to a weld along the entire perimeter of the package. MCL’s processing is for Kovar™ with Au on top of Ni plate. The weld is an Au/Ni/Fe/Co alloy passing method 1019 salt atmosphere.
Projection welding of TO Style packages provides precise control over the internal package atmosphere. Prior to the hermetic cover seal, the unsealed package is processed with a deep vacuum bake moisture removal process. Hermetic sealing is then performed in a controlled inert environment including H20 ppm, 02 ppm and 0.1µ particulate filtration.
