Hello,
There is only one Institute in Sikkim which provides Diploma in Mechatronics Engineering course. It is Advanced Technical Training Centre, Sikkim.

Diploma in Mechatronics Engineering is a three-year full-time course offered by the Directorate of Technical Education, Sikkim and approved by All India Council for Technical Education (AICTE).

The eligibility criteria is to be passed 10th Std./ SSC examination and Obtained at least 35% marks in the qualifying examination.

For more details please visit this link https://www.careers360.com/colleges/advanced-technical-training-centre-sikkim/diploma-in-mechatronics-engineering-course

Hope it helps