Hello dear student, 

There are criterias for placement, every company have it's own criteria. But don't worry there are very less companies who ask for the 12th marks . Maximum companies ask for the students with more than 60% in 12th while your marks in the graduation matters . Try to keep them above 70 even if you have 60% then also its not a big deal as marks do not tell your potential may be your concepts are good . And may be you perform well in front of them. 

I hope this is helpful

Best wishes