Process for the correction of curls of flexible metal clad laminate and for the improvement of its dimensional stability

Claim 1

A process for the correction of curls of a long flexible metal clad laminate, which has a thin aromatic polyimide film formed directly on a long metal foil without any adhesive interposed therebetween, and for the improvement of the dimensional stability thereof, characterized in that said process comprises the steps, performed at least once per step in any arbitrary order, of (1) causing the laminate to slide under tension, along the length thereof, on a curved surface of a first bar arranged at an angle of 30-60 degrees relative to the width of the laminate with the metal foil inside so that the metal foil faces said first bar; (2) causing the laminate to slide under tension, along the length thereof, with the metal foil inside, on a curved surface of a second bar arranged at an angle of 60-120 degrees relative to the first bar; (3) causing the laminate to slide under tension, along the length thereof, with the polyimide film inside, on a curved surface of a third bar or first rotating roll arranged at an angle of 30-60 degrees relative to the width of the laminate; and (4) causing the laminate to slide under tension, along the length thereof, with the polyimide film inside, on a curved surface of a fourth bar or second rotating roll arranged at an angle of 60-120 degrees relative to the third bar or first rotating roll.