Microelectronic die packages, stacked systems of die packages, and methods of manufacturing thereof are disclosed herein. In one embodiment, a method of manufacturing a microelectronic device includes stacking a first die package having a first dielectric casing on top of a second die package having a second dielectric casing, aligning first metal leads at a lateral surface of the first casing with second metal leads at a second lateral surface of the second casing, and forming metal solder connectors that couple individual first leads to individual second leads. In another embodiment, the method of manufacturing the microelectronic device may further include forming the connectors by applying metal solder to a portion of the first lateral surface, to a portion of the second lateral surface, and across a gap between the first die package and the second die package so that the connectors are formed by the metal solder wetting to the individual first leads and the individual second leads.