Calcutta University is not very good for BTech. Academics is good there but you won't see good placements there. They have got different departments but they are not very good 

Moreover if you have options you should look for the top colleges in West Bengal like

• Jadavpur University 
• IIEST Shibpur 
• WBUT 
• Heritage Institute of Technology 
• IEM Kolkata 
• Jalpaiguri Government Engineering college and the like. These are good colleges for BTech. 

Good luck