A method of fabricating a substrate (200, 300) comprising: forming a first portion (210, 310) of the substrate including forming a first plurality of metal layers (214, 314) comprising a metal layer (214d M4, 314d M4) that is located on a first surface of the first portion (210, 310) of the substrate (200, 300); forming a second portion (250, 350) of the substrate (200, 300) including forming a second plurality of metal layers (254, 354) comprising another metal layer (254d M4, 354d M4) that is located on a second surface of the second portion (250, 350) of the substrate (200, 300); forming a plurality of insulating layers (216, 256, 316, 356) configured to separate the first plurality of metal layers and the second plurality of metal layers; forming a first plurality of pads located on the first metal layer (214d M4, 314d M4), and a second plurality of pads located on the second metal layer (254d M4, 354d M4); forming a first plurality of posts (230, 330) located on the first plurality of pads and a plurality of solder interconnects (234, 368) located on the second plurality of pads; coupling the first plurality of posts to the plurality of solder interconnects such that (i) the first portion of the substrate and the second portion of the substrate are coupled together, and (ii) the first surface of the first portion of the substrate faces the second surface of the second portion of the substrate, wherein coupling the first plurality of posts to the plurality of solder interconnects forms a gap (298, 398) between the first portion of the substrate and the second portion of the substrate; and after coupling the first plurality of posts to the plurality of solder interconnects, filling the gap with a mold, such that the mold fills a gap between the first plurality of pads and between the first plurality of posts (230, 330). forming a first portion (210, 310) of the substrate including forming a first plurality of metal layers (214, 314) comprising a metal layer (214d M4, 314d M4) that is located on a first surface of the first portion (210, 310) of the substrate (200, 300); forming a second portion (250, 350) of the substrate (200, 300) including forming a second plurality of metal layers (254, 354) comprising another metal layer (254d M4, 354d M4) that is located on a second surface of the second portion (250, 350) of the substrate (200, 300); forming a plurality of insulating layers (216, 256, 316, 356) configured to separate the first plurality of metal layers and the second plurality of metal layers; forming a first plurality of pads located on the first metal layer (214d M4, 314d M4), and a second plurality of pads located on the second metal layer (254d M4, 354d M4); forming a first plurality of posts (230, 330) located on the first plurality of pads and a plurality of solder interconnects (234, 368) located on the second plurality of pads; coupling the first plurality of posts to the plurality of solder interconnects such that (i) the first portion of the substrate and the second portion of the substrate are coupled together, and (ii) the first surface of the first portion of the substrate faces the second surface of the second portion of the substrate, wherein coupling the first plurality of posts to the plurality of solder interconnects forms a gap (298, 398) between the first portion of the substrate and the second portion of the substrate; and after coupling the first plurality of posts to the plurality of solder interconnects, filling the gap with a mold, such that the mold fills a gap between the first plurality of pads and between the first plurality of posts (230, 330).