120 MHz Cortex-M4 with 2 MB Flash — the high-density STM32L4R flagship
This is the top-end density option in the STM32L4R family, targeting applications that need both the M4 DSP/FPU throughput and the large code store — think advanced sensor fusion, graphics-capable HMI panels, or multi-protocol IoT gateways running at industrial temperature (-40°C to 85°C).
WLCSP package — what it means for assembly and rework
The 144-WLCSP (wafer-level chip-scale package) is a bare-die footprint with solder balls directly on the silicon — no plastic overmold. The 5.24x5.24 mm body saves board area but demands tighter PCB registration and a reflow profile tuned for lead-free solder. MSL is typically 3 for this package class; if the moisture-barrier bag has been open beyond the floor-life window, a bake at 125°C for 48 hours is needed before reflow. The fine ball pitch (0.4 mm nominal) rules out hand-soldering; X-ray inspection of the BGA joints is the standard post-reflow check. For a rework lab, hot-air rework with a bottom preheat zone keeps the adjacent balls from cold-jointing.
The base product number is STM32L4R9, and the series STM32L4R remains an active ST portfolio line. ROHS3 compliance is confirmed.
Supply voltage and temperature — industrial-grade margin
The 120 MHz core speed holds across the full temperature range as long as the Flash wait states are configured per the datasheet (one wait state at 120 MHz).