Memory budget for a typical firmware load
The STM32F031F4P6: 16 KB Flash and 4 KB SRAM fit a bootloader plus a single application loop.
The 20-TSSOP package with 0.65 mm pitch and 4.4 mm body width is hand-solderable and reflow-friendly at MSL 3. For designs that see sustained junction temperatures above 85°C, step up to the STM32F0 extended-temperature variants or the STM32F051 family with a 105°C rating.
Active lifecycle — no near-term obsolescence concern
The STM32F0 series is a mature, volume-driven platform; PCNs are rare and usually limited to wafer-fab or assembly-site changes.