Tall solders for through-mold interconnect

A system, comprising:

• a first microelectronic chip package including a first die situated on an upper surface of a first substrate and a solder ball situated on a lower surface of the first substrate;
• a second microelectronic chip package situated below the lower surface of the first substrate, the second microelectronic package including:
• a second die situated on a top surface of a second substrate,
• a molding disposed over the upper surface of the second substrate, the molding extending over the circuit and including an opening extending from an upper surface of the molding towards an upper surface of the second substrate, wherein the opening is configured to admit at least a portion of the solder ball and wherein the opening defines a cylindrical portion extending down to the upper surface of the second substrate and a frustoconical portion coextensive with the cylinder, opening away from the cylinder and extending to the upper surface of the molding, and
• a solder column mechanically coupled to the second substrate, situated in the opening, conforming to the cylinder, and extending above the upper surface of the second substrate to a height sufficient to electrically couple with the solder ball when the solder ball is at least partially situated in the opening and reflowed, wherein the solder column conforms to the cylindrical portion and to at least a portion of the frustoconical portion, wherein the solder column includes at least two layers of solder with flux therebetween, a first layer of solder of the at least two layers of solder conforming to the cylindrical portion of the opening and a second layer of solder of the at least two layers of solder conforming to the frustoconical portion of the opening;
• and
• a printed circuit board electrically and mechanically coupled to a second solder ball on the lower surface of the second substrate.