Multilayer wiring board and manufacturing method for the multilayer wiring board

1. A manufacturing method for a multilayer wiring board, the manufacturing method comprising:

forming a groove on a surface of a first thermoplastic resin board;

forming a modified layer made of resin having a melting point lower than a melting point of resin constituting the first thermoplastic resin board, by applying light to a region of the surface of the first thermoplastic resin board other than a region around the groove;

filling the groove of the first thermoplastic resin board with conductive material having fluidity; and

bonding a second thermoplastic resin board to the surface of the first thermoplastic resin board, on which the modified layer is formed, by thermocompression bonding,

wherein a width in plan view of the region around the groove between the groove and the region of the surface of the first thermoplastic resin board other than the region around the groove is 10 μm or more.

2. The manufacturing method according to claim 1 , wherein the second thermoplastic resin board is heated to a temperature that is higher than the melting point of the resin constituting the modified layer and that is lower than the melting point of the resin constituting the first thermoplastic resin board, in the thermocompression bonding.

3. The manufacturing method according to claim 1 , wherein the groove is formed by repeatedly applying ultraviolet laser light having a wavelength of 250 nm or less and having power of 1 W or less per appliance of light.

4. The manufacturing method according to claim 3 , wherein the modified layer is formed by applying the ultraviolet laser light used as the light.

5. The manufacturing method according to claim 4 , wherein the modified layer is formed by applying the ultraviolet laser light used as the light only once.

6. The manufacturing method according to claim 1 , wherein a distance between the groove and the modified layer is 10 μm or more.

7. The manufacturing method according to claim 1 , wherein a width in plan view of the region around the groove between the groove and the region of the surface of the first thermoplastic resin board other than the region around the groove is 10 μm or more and 50 μm or less.