Electronic device having a soldered joint between a metal region of a semiconductor die and a metal region of a substrate

An electronic device, comprising:

• a first semiconductor die having a metal region;
• a substrate comprising a ceramic and a metal layer directly attached to the ceramic, wherein a plurality of metal regions is patterned into the metal layer;
• a first soldered joint between the metal region of the first semiconductor die and the metal layer directly attached to the ceramic, the first soldered joint having one or more intermetallic phases throughout the entire soldered joint, each of the one or more intermetallic phases formed from a solder preform diffused into the metal region of the first semiconductor die and the metal layer directly attached to the ceramic, at least one of the intermetallic phases comprising metal consumed from the metal region of the first semiconductor die and at least one of the intermetallic phases comprising metal consumed from the metal layer directly attached to the ceramic, each of the intermetallic phases having a melting point above both a melting point of the solder preform and a soldering temperature at which the solder preform diffused into the metal region of the first semiconductor die and the metal layer directly attached to the ceramic;
• and
• a second semiconductor die soldered to the metal layer directly attached to the ceramic.