Liquid crystal polymer film, laminate, method of making them and multi-layered parts-mounted circuit board

A method of making a liquid crystal polymer film in which a film comprising a polymer capable of forming an optically anisotropic melt phase (which polymer is hereinafter referred to as a liquid crystal polymer) is, after having been laminated on a base material capable of supporting a shape of the film during heat treatment, heat-treated a number of times in the following manner and the base material is subsequently removed to provide the liquid crystal polymer film:

• First Heat Treatment:
• This first heat treatment is carried out at a temperature range of from the thermal deformation temperature Tdef of the polymer film to a temperature lower by α° C. than the melting point Tm of the polymer film before the heat treatment (i.e., Tdef˜(Tm−α° C.)), until the fusion peak temperature TA of the polymer film being heat-treated, which temperature TA is measured by the use of a differential scanning calorimeter under the atmosphere of nitrogen with temperature increased at a speed of 5° C. per minute, attains a temperature TA1 which is higher by β° C. than the melting point Tm of the polymer film before the heat treatment, wherein α represents 10 to 35° C. and β represents 5 to 30° C.
• Second Heat Treatment:
• This second heat treatment is carried out at a temperature range of from a temperature not lower than the melting point Tm of the polymer film before the heat-treatment to a temperature lower than the fusion peak temperature TA1 until the fusion peak temperature TA1 attains a temperature TA2 that is increased γ° C. from the fusion peak temperature TA1, wherein γ represents 5to 20° C.
• n-th Heat Treatment:
• This n-th heat treatment is carried out at a temperature range of from the fission peak temperature TAn−2 to a temperature lower than the fission peak temperature TAn−1 until the fusion peak temperature TAn−1 attains a temperature TAn that is increased γ° C. from the fuision peak temperature TAn−1, wherein n represents an integer equal to or larger than 3 and γ represents 5 to 20° C.