Flexible laminated board and multilayer circuit board

A method for manufacturing a laminated sheet that is formed by laminating an insulation film formed of a polymer of 6-hydroxy-2-naphthoic acid and 4-hydroxybenzoic acid and a metal foil together and used to manufacture a multilayer circuit board, the method comprising steps of:

• drying the insulation film by heating the insulation film at a temperature of 120° C. to 250° C. for 20 seconds or longer;
• and
• thermocompression-bonding the dried insulation film onto the metal foil to form a laminated sheet by pressing the dried insulation film and the metal foil against each other with a pressure of 0.5 MPa to 10 MPa for 10 seconds to 600 seconds while heating the dried insulation film and the metal foil at a temperature of 250° C. to 330° C., wherein
• the insulation film obtained by removing the metal foil from the laminated sheet after the step of thermocompression bonding has a maximum deformation rate of less than or equal to 0.85% at 250° C. to 300° C. measured with a dynamic viscoelasticity measurement device under the conditions in which the dynamic load is 15 g, the frequency is 1 Hz, and the rate of temperature increase is 5° C./min while controlling the dynamic stress and the static load in a dynamic stress control mode and an automatic static load mode.