1 – Price is important since it is an intermediate step and does not have any value once the process is important. For these reasons, look for a a polyester instead of a polyimide. Polyester is good for intermittent (5 mins or so) at 180°C and are much less expensive than a polyimide film.

2 – No adhesive residue after removal. You didn’t apply the masking tape only to have it leave an adhesive layer after removal. For this reason, look for a low-adhesion bonding material.

3 – Backing thickness. For handling these materials, 1mil thickness may (but is not always) be too thin. You want to choose a thickness that meets your needs without going any thicker. Extra thickness means extra cost that you will just throw away once the process is complete.

CAPLINQ recommends three potential materials, listed in order of recommendation (links are to the products technical datasheets):
a) PET1.5A-ULA-RL: 1.5-mil polyester film backing with an ultra-low-adhesion pressure sensitive acrylic adhesive on a paper release liner. It is designed to be a temporary bonding or masking tape for use in a wide range of applications.

b) PET2SG: Difference with the one above is that it is not on a release liner, is 2mil thick (instead of 1.5mil) and uses a silicone adhesive. Designed for applications that need slightly higher adhesion and temperature resistance and do not want a release liner.

c) PET1S: Difference with first one is that it is only 1mil thick and uses silicone and no release liner.