Looking for a non-conductive heat resistant tape to fill gap in PC

Hi,
I have a notebook, and there is a flaw in the design. there is quite a big gap between the Heatsink and the fans.
where can I find a shop that sells reliable duct tape that is 100% non-conductive and heat resistant
I asked the nearby shops but the best they had was the regular electrical tape " shertaton "


Thanks,