A POP (Package-On-Package) semiconductor device with encapsulating protection of soldered joints between the external leads, primarily comprises a plurality of stacked semiconductor packages and dielectric coating. Each semiconductor package includes at least a chip, a plurality of external leads of leadframe, and an encapsulant where the external leads are exposed and extended from a plurality of sides of the encapsulant. Terminals of a plurality external leads of a top semiconductor package are soldered to the soldered regions of the corresponding external leads of a bottom semiconductor package. The dielectric coating is disposed along the sides of the encapsulant of the bottom semiconductor package to connect the soldered points between the external leads and to partially or completely encapsulate the soldering materials so that the stresses between the soldered joints can be dispersed and no electrical shorts happen.