The technology of fan-out wafer level packaging (FOWLP) has been widely adopted for millimeter wave antenna-in-package (AiP) system integration with low interconnection parasitic parameters. Present AiP solutions using FOWLP technology generally form antenna pattern on redistribution layer, which brings design inconvenience. In our work, a low-cost printed circuit board RO4350B laminate for substrate-integrated waveguide (SIW) antenna with a relatively large size is integrated, forms a three-dimensional stacked structure. The AiP employs a right-angle transition board embedded in epoxy molding compound (EMC), which transmits millimeter-wave signal to the SIW antenna stacked on the backside of EMC. The SIW antenna consists of 4 × 4 radiation slots with modified magneto-electric dipole for bandwidth enhancement. The measured gain is 14dBi at 60 GHz with bandwidth beyond 55–65 GHz. The three-dimensional AiP structure improves heat dissipation, no extra thermal design is needed for applications under 0.5 W mm-wave chip power consumption. The AiP module is manufactured and measured on the test board. The proposed approach is a convenient solution for wide band and high gain millimeter wave AiP system integration.