Laser sintered interconnections between die

A method for fabricating a microelectronic packaged device, the method comprising:

• depositing nanoparticle paste in an area over a face-up surface of a system package, wherein
• the system package includes at least a first die and a second die having minor sidewall surfaces surrounded by mold compound, the first and second die are laterally positioned to one another, the first die and the second die each have an exposed major surface at the face-up surface of the system package, and
• the area includes a target path between a first conductive surface on the exposed major surface of the first die and a second conductive surface on the exposed major surface of the second die, the target path crosses a face-up surface of a portion of the mold compound located between the first and second die;
• locating a position of the first and second conductive surfaces relative to one another using fiducial marks on the exposed major surfaces of the first and second die;
• and
• forming a conductive trace along the target path between the first and second conductive surfaces, wherein the conductive trace is laser sintered directly on the first conductive surface, directly on the exposed major surface of the first die, directly on the face-up surface of the portion of the mold compound, directly on the exposed major surface of the second die, and directly on the second conductive surface, wherein the exposed major surface of the first die comprises a backside surface of the first die, and wherein the first die comprises an active surface opposite the backside surface.