(1) The thickness of the composite film is not consistent.
(2) Heat sealing temperature is too high or heat sealing time is too long.
(3) In the longitudinal heat sealing knife part, the running track of the composite film is not straight.
(4) Insufficient cooling.
(5) The maturation time is not enough.
(6) The heat resistance of the surface substrate film is poor.
(7) Improper tension matching control of composite substrate in the composite process leads to residual stress after its ripening and shaping, especially when the composite film thickness is thin, such failure is more likely to occur.
