Flexible laminated board and multilayer circuit board

Abstract

A flexible laminated sheet manufacturing method includes thermocompression-bonding an insulation film formed of a liquid crystal polymer onto a metal foil between endless belts to form a flexible laminated sheet. The thermocompression bonding includes heating the flexible laminated sheet so that the maximum temperature of the sheet is in the range from a temperature that is 45° C. lower than the melting point of the liquid crystal polymer to a temperature that is 5° C. lower than the melting point. The thermocompression bonding also includes slowly cooling the flexible laminated sheet so that an exit temperature, which is a temperature of the sheet when transferred out of the endless belts, is in the range from a temperature that is 235° C. lower than the melting point of the liquid crystal polymer to a temperature that is 100° C. lower than the melting point.

2 . A method for manufacturing a flexible laminated sheet, the method comprising steps of:
 continuously feeding an insulation film formed of a liquid crystal polymer and a metal foil between a pair of two endless belts; and   thermocompression-bonding the insulation film onto the metal foil between the endless belts to form a flexible laminated sheet, wherein   the step of thermocompression bonding includes   heating the flexible laminated sheet so that the maximum temperature of the flexible laminated sheet is in the range from a temperature that is 45° C. lower than the melting point of the liquid crystal polymer of the insulation film to a temperature that is 5° C. lower than the melting point, and   slowly cooling the flexible laminated sheet so that an exit temperature, which is a temperature of the flexible laminated sheet when transferred out of the endless belts, is in the range from a temperature that is 235° C. lower than the melting point of the liquid crystal polymer of the insulation film to a temperature that is 100° C. lower than the melting point.   
     
     
         3 . The method for manufacturing a flexible laminated sheet according to  claim 2 , wherein the insulation film is formed of a liquid crystal polymer containing as constituent units 6-hydroxy-2-naphthoic acid and para-hydroxybenzoic acid and having a melting point in excess of 250° C. 
     
     
         4 . The method for manufacturing a flexible laminated sheet according to  claim 2 , wherein the metal foil is at least one selected from the group consisting of a copper foil, an aluminum foil, a stainless steel foil, and a foil formed of an alloy of copper and aluminum. 
     
     
         5 . 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.   
     
     
         6 . A multilayer circuit board formed by laminating a plurality of pattern films into a multilayer, wherein each pattern film is formed by circuit-processing the laminated sheet obtained through the method for manufacturing a laminated sheet according to  claim 5 , and wherein the insulation film contained in each of the pattern films includes a via hole filled with an interlayer connection material.