Methods for manufacturing thermoplastic liquid crystal polymer film and circuit board

A method for producing a thermoplastic liquid crystal polymer film, as an adhesive film, suitable to be thermo-bonded to a thermoplastic liquid crystal polymer film, as an adherend film, the method comprising:

• preparing a first thermoplastic liquid crystal polymer film, as the adherend film, and a second thermoplastic liquid crystal polymer film, as the adhesive film;
• subjecting each of first and second surface portions to be adhered of the first and second thermoplastic liquid crystal polymer films prepared to X-ray photoelectron spectroscopy (XPS) analysis so as to obtain an XPS spectral profile of the first and second surface portions;
• examining a relative intensity of each of the thermoplastic liquid crystal polymer films prepared, the relative intensity being calculated as a ratio of a sum of peak areas of C—O bond peak and COO bond peak relative to a total area of C is peaks in the XPS spectral profile, as a first relative intensity X in percent, for the adherend film, and a second relative intensity Y in percent, for the adhesive film;
• and
• controlling, by activation treatment, the adhesive film to have the second relative intensity Y such that the first relative intensity and the second relative intensity Y satisfy formulae (1) and (2):
• 38≤X+Y≤65 (1)
• −8.0≤Y−X≤8.0 (2)
• wherein the method further comprises:
• copolymerizing and forming the adhesive film, after the copolymerizing, degassing the adhesive film before or after the controlling of the second relative intensity Y by degassing the second thermoplastic liquid crystal polymer film
• (i) under vacuum of 1500 Pa or lower for 30 minutes or more, or
• (ii) under heating at a temperature in a range of from 100 to 200° C., or
• (iii) under the vacuum (i) and under the heating (ii) simultaneously or separately.