Hii Uma mam,

You just need to know that many students join diploma in mechanical engineering after 10th. After completing their 3 year diploma you can get direct admission in b. tech 2nd year through lateral entry . ... Admission will be based on state entrance examination or college have their own examination for this.

Mam after diploma he'll be able to choose other branch but it'll be more worth if he chooses from the stream he pursued diploma:

1. mechatronics engineering
2. auto mobile engineering
3. mechanical engineering
4. production engineering

I hope this helps you mam.

Best of luck for son's future endeavours.