You want just the bare chips? If yes I would say you are probably going to have to salvage them from usb miners 5 at a time... I looked on alibaba for a while it might have the ic you need but i don't know i think it would be more fruitful and cheaper to buy used usb 5 chip miners and carefully remove them than find the chips. But even if you made a custom board with 1000s of those chips they would use more power than they generate in coin...