I don't think there should be any custom duty for ASICs(max 7.5%) here's why:
https://flic[dot]kr/p/XwT4G3
From the PDF of chapter 85 from 8542 31 00:
Electronic integrated circuits:
8542 31 00 -- Processors and controllers, whether u Free -
or not combined with memories,
converters, logic circuits, amplifiers,
clock and timing circuits, or other circuits
8542 32 00 -- Memories u Free -
8542 33 00 -- Amplifiers u Free -
8542 39 00 -- Other u 7.5% -
8542 90 00 - Parts kg. Free
Link:
http://www.cbec.gov.in/htdocs-cbec/customs/cst1617-300616/cst1617-3006-idx