Solid place, but watch your team's workload.
Overall, STMicroelectronics is a pretty stable place to work in the semiconductor industry. Work-life balance really depends on your specific project and manager, especially as a Senior Design Engineer.
I've had decent work-life balance for the most part, especially with the hybrid model. It's usually a standard 40-hour week if you're not on a critical project phase. The Santa Clara office has good amenities too.
When deadlines hit, it can get tough. We've had some late nights during tape-out for specific ASIC projects. It's not consistent across all teams; some managers expect more overtime.
Try to standardize expectations around project timelines and overtime. Some teams are much better than others, which creates an imbalance for employees.