Method for manufacturing substrate for flexible printed wiring board, and substrate for flexible printed wiring board

A method for manufacturing a substrate for flexible printed wiring board, comprising

• a laminated body forming step and an integration step, wherein
• in the laminated body forming step,
• on an upper surface and a lower surface of a fluororesin layer having a modified surface, a first and second reinforcing resin layers having a coefficient of thermal expansion smaller than that of the fluororesin layer are respectively stacked through a first thermosetting adhesive,
• on the first reinforcing resin layer and/or the second reinforcing resin layer, a single-sided conductor-clad laminate including a conductor layer and a third reinforcing resin layer stacked on one surface of the conductor layer is stacked through a second thermosetting adhesive so that the conductor layer faces outward, to form a laminated body, and
• in the integration step,
• the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer.

A method for manufacturing a substrate for flexible printed wiring board, comprising:

• preparing a fluororesin layer having a modified surface;
• preparing a first single-sided conductor-clad laminate including a first conductor layer and a first reinforcing resin layer stacked on one surface of the first conductor layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• preparing a second single-sided conductor-clad laminate including a second conductor layer and a second reinforcing resin layer stacked on one surface of the second conductor layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• and
• a laminated body forming step and an integration step, wherein
• in the laminated body forming step,
• on an upper surface of the fluororesin layer, the first single-sided conductor-clad laminate is stacked through a first thermosetting adhesive so that the first conductor layer faces outward,
• on a lower surface of the fluororesin layer, the second single-sided conductor-clad laminate is stacked through a second thermosetting adhesive so that the second conductor layer faces outward, to form a laminated body, and
• in the integration step,
• the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer,
• wherein the first thermosetting adhesive is formed over an entire surface of the fluororesin layer.

A substrate for flexible printed wiring board, comprising:

• a fluororesin layer having a modified surface;
• a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• and
• a conductor layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer through a third cured adhesive layer,
• wherein the first cured adhesive layer is formed over an entire surface of the fluororesin layer.

A substrate for flexible printed wiring board, comprising:

• a fluororesin layer having a modified surface;
• a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• a third reinforcing resin layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer through a third cured adhesive layer;
• and
• a conductor layer stacked on the third reinforcing resin layer.

A substrate for flexible printed wiring board, comprising:

• a fluororesin layer having a modified surface;
• a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer;
• and
• a conductor layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer,
• wherein the first cured adhesive layer is formed over an entire surface of the fluororesin layer.