MTech placements for the ECE branch at IIT Kharagpur depend a lot on your specialization. 

Those under VLSI and VIPES get placed with great packages and there are almost cent percent placements for them. VLSI students are usually offered core jobs in contrast to VIPES which offers both core and non-core jobs. There are a lot of software profiles offered to VIPES students. 

Communication also has decent placements but not the same certainty as VLSI. Here companies like Qualcomm come for placements and some even are offered software profilers