Company is very focused on the short-term. In the last four years there have been four rounds of layoffs. Yet I still saw senior managers driving luxury rental cars on the company dime. When someone leaves, their position is often not back-filled, and everyone else has to just do more work to make up for it. Same for laid-off positions.
Forced time off is an annual tradition. Plan on using a large block of your vacation every year around Christmas and New Year's. Additionally, over the past couple of years it has become common for management to require 10 days of vacation time to be used in a quarter, usually in calendar Q1 or Q4, or both. If you want to take vacation in the summer, there's always the option of going unpaid during forced shut downs. And this isn't just manufacturing - all employees are required to take the time off unless they are somehow protected by local law.
Business units are extremely siloed and many managers try to build up their own private fiefdoms. There is little coordination or cooperation between separate groups or business units, even when they're in the same physical location or they report to the same senior manager.
ON Semi's spree of buying companies or parts of companies seems like a good thing, but it just results in more layoffs at both the acquired company and the parent company. Integration generally goes poorly.
The workplace is mostly made up of lifers who have survived round after round of job cuts and consolidation. It can be difficult to fit in if you weren't with the company 15 or more years ago. There are some very good people, but there are also those who seem to be promoted because being a jerk is a desired managerial trait.
Technologically, ON Semi is mid-range at best, a laggard at worst. "Cutting-edge" is a phrase you will likely never hear tied to ON Semiconductor.