T-F series is a 3-layer co-extruded (ABA structured) PET film. Layer A is UV-resistant while layer B is hydrolysis resistant. Through series tests of mechanical property, electric property, damp heat aging, and UV aging, its properties of UV resistance and damp heat resistance turn out to be excellent. Exposed in 300kwh/m2 UV radiation, its yellowness index keeps in 4.0. Its elongation at break reaches 69% under the 121℃ damp heat test for 60 hours. Using such PET films in the production of poly-silicon solar cell back sheets, the panel property can be greatly improved. Special requirements on film thickness can be settled upon negotiation. The recommended thickness is 125μm and 150μm.