Varied ball ball-grid-array (BGA) packages

An electronic system, comprising:

• a first substrate;
• a second substrate;
• first solder balls coupling the first substrate to the second substrate, the first solder balls having a first total chemical composition;
• a third substrate;
• and
• second solder balls coupling the second substrate to the third substrate, the second solder balls having a second total chemical composition different than the first total chemical composition of the first solder balls, and the second solder balls comprising a metallic core surrounded by a solder, a first portion of the first solder balls aligned in a row proximate to a first edge of the second substrate, and a second portion of the first solder balls aligned in a row proximate to a second edge of the second substrate, the second opposite the first edge.

A package comprising:

• a first substrate;
• a second substrate;
• an array of interconnects between the first substrate and the second substrate, the array of interconnects including a plurality of first interconnects and a plurality of second interconnects, each of the first interconnects including a first solder comprising tin, and each of the second interconnects comprising a copper core and a second solder surrounding the copper core, the second solder comprising tin, wherein each of the plurality of first interconnects has a first total chemical composition, and each of the plurality of second interconnects has a second total chemical composition different than the first total chemical composition;
• and
• wherein the array of interconnects includes corner regions and a middle, at least one of the second interconnects located in one of the corner regions and at least one of the first interconnects located in the middle.

A packaging, comprising:

• a first substrate;
• a second substrate;
• an array of interconnects between the first substrate and the second substrate, the array of interconnects including a first interconnect, a second interconnect, a third interconnect, and a fourth interconnect, wherein each of the first interconnect and the second interconnect includes a first solder, and each of the third interconnect and the fourth interconnect includes a copper core having a diameter of 250 um or less, and a second solder surrounding the copper core, the second solder having a thickness approximately 1 um or greater, wherein each of the first interconnect and the second interconnect has a first total chemical composition, and each of the third interconnect and the fourth interconnect has a second total chemical composition different than the first total chemical composition;
• and
• wherein at least one of the third interconnect and the fourth interconnect is located at a perimeter of the array of interconnects, wherein at least one of the first interconnect and the second interconnect is located at a middle of the array of interconnects, and wherein at least one of the third interconnect and the fourth interconnect is located at a corner region of the array of interconnects.

A packaging, comprising:

• a first substrate;
• a second substrate;
• an array of interconnects between the first substrate and the second substrate, the array of interconnects including a plurality of first interconnects and a plurality of second interconnects, each of the first interconnects including tin, and each of the second interconnects comprising a copper core having a diameter of 250 um or less, and tin surrounding the copper core, wherein each of the plurality of first interconnects has a first total chemical composition, and each of the plurality of second interconnects has a second total chemical composition different than the first total chemical composition;
• and
• wherein a height between the first substrate and the second substrate is at least the diameter of the copper core, wherein the array comprises:
• a corner region, wherein at least one of the second interconnects is located in the corner region;
• and
• a middle, wherein at least one of the first interconnects is located in the middle.