Thermoplastic liquid crystal polymer film, circuit board, and methods respectively for manufacturing said film and said circuit board

A circuit board, comprising a plurality of circuit board materials and having a predetermined structure, wherein:

• the circuit board materials are at least one member selected from the group consisting of an insulating substrate having a conductor layer on at least one surface, a bonding sheet, and a coverlay;
• at least one of the circuit board materials comprises a thermoplastic liquid crystal polymer film in contact with a circuit board material;
• the circuit board shows solder heat resistance when the circuit board is placed in a solder bath at a temperature of 290° C. for 60 seconds in accordance with a method of JIS C 5012;
• and
• where the thermoplastic liquid crystal polymer film and the circuit board material are peeled off along a first direction (A direction) or along a second direction (B direction) perpendicular to the first direction to measure the bonding strength between the thermoplastic liquid crystal polymer film and the circuit board material in accordance with JIS C5016-1994, the minimum value of bonding strength in four directions of a forward A direction, an adverse A direction, a forward B direction, and an adverse B direction is:
• (i) 0.5 kN/m or higher where the circuit board material is an insulating substrate material, or
• (ii) 0.25 kN/m or higher where the circuit board material is a conductor layer,
• wherein the thermoplastic liquid crystal polymer film has a segment orientation ratio SOR of 0.8 to 1.4 and a moisture content of 300 ppm or less, and the thermoplastic liquid crystal polymer film has been subjected to at least one degassing process:
• (i) by degassing the thermoplastic liquid crystal polymer film under vacuum of 1500 Pa or lower for 30 minutes or more,
• (ii) by degassing the thermoplastic liquid crystal polymer film under heating at a temperature ranging from 100° C. to 200° C., or
• (iii) by degassing the thermoplastic liquid crystal polymer film under the degassing processes (i) and (ii) simultaneously or separately.