There are known a laminator that pressure-bonds a film containing a photosensitive material (a photoresist) onto one side or each of both sides of a substrate with use of a pair of pressure-bonding rolls. The laminator supplies the substrate into between the pair of pressure-bonding rolls and also supplies the film onto at least one surface of the substrate, sandwiches the substrate and the film between the pair of pressure-bonding rolls, and heats the substrate while causing the pair of pressure-bonding rolls to apply a predetermined pressing force toward a substrate side, thereby pressure-bonding the film onto the substrate. The substrate with the film pressure-bonded thereon in this manner is exposed to light, by which a conductive pattern or the like is formed on this substrate.
Generally, a pressing force to the pressure-bonding rolls is applied to bearing housings that support bearings provided at both ends of the pressure-bonding rolls, with use of an actuator, such as an air cylinder. This commonly used laminator leads to application of the pressing force to the both ends of the pair of pressure-bonding rolls toward the substrate side. Therefore, when a relatively thick substrate is processed, a bending moment (hereinafter referred to as a first bending moment) is generated on the pair of pressure-bonding rolls with edges of both ends of the substrate serving as supports As a result, the pressure-bonding rolls are each deformed into such an arch shape that a center thereof is distanced farther away from the substrate than the both ends thereof. This deformation results in uneven application of the pressing force from the pressure-bonding rolls to the substrate and the film in a direction in which the pressure-bonding rolls extend.
Under such environments, there is developed a technique that allows the pressure-bonding rolls to apply the pressing force so as to generate a second bending moment in an opposite direction from the first bending moment at the same time as generating the first bending moment (for example, the following patent literatures, PTLs 1 and 2). According to this technique, the first bending moment and the second bending moment cancel out each other's influence causing the bending of the pressure-bonding rolls, which can reduce the deformation of the pressure-bonding rolls to thereby improve the unevenness of the pressing force. Further, another possible method is to form each of the pressure-bonding rolls in such a manner that an outer diameter thereof is increasing from the both ends toward the center, thereby establishing even contact between a shape of the arched deformed pressure-bonding roll and shapes of the substrate and the film to improve the unevenness of the pressing force. The roll shaped in this manner is called a crown roll.