Just wrapped up one of my PCB design — a 4-layer STM32H743VIT6 baord built around a high pin-count MCU (LQFP-100, 80+ pins used).

Key Features:
• 20+ GPIOs with ADC & DAC (interrupt-driven)
• Dedicated RC filtering for analog signals
• CAN, 2× UART, 2× I²C, 2× SPI
• External crystal + external flash
• USB Type-C with protection & impedance-controlled routing (~90Ω)
• Onboard sensors: IMU + environmental (ICM-30002, BME280)
• SWD debugging interface

PCB Stackup:
• 4-layer design: Signal / GND / Power / GND
• Controlled impedance routing for high-speed lines

This board isn’t perfect — and that’s where most of the learning came from.
• Some ADC traces ended up longer than ideal
• SWD routing had to be pushed to bottom layer due to placement mistakes
• Bottom ground plane got fragmented because of routing decisions
• A few filters and decoupling caps were placed sub-optimally

A Good PCB design is 70% placement, 30% routing

It will be helpful if you share your thoughts and feedback for further improvement.