Inductor built-in substrate
An inductor built-in substrate includes a core substrate having an opening and a first through hole formed therein, a magnetic resin filling the opening and having a second through hole formed therein, a first through-hole conductor including a metal film formed in the first through hole, and a second through-hole conductor including a metal film formed in the second through hole. The core substrate and the magnetic resin are formed such that a surface in the first through hole has a roughness that is larger than a roughness of a surface in the second through hole.
1. An inductor built-in substrate, comprising:
a core substrate having an opening and a first through hole formed therein;
a magnetic resin filling the opening and having a second through hole formed therein;
a first through-hole conductor comprising a metal film formed in the first through hole; and
a second through-hole conductor comprising a metal film formed in the second through hole,
wherein the core substrate and the magnetic resin are formed such that a surface in the first through hole has a roughness that is larger than a roughness of a surface in the second through hole.
2. The inductor built-in substrate according to claim 1 , wherein the core substrate is a resin substrate having a core material.
3. The inductor built-in substrate according to claim 1 , wherein the magnetic resin includes iron oxide filler in an amount of 60% by weight or more.
4. The inductor built-in substrate according to claim 3 , wherein the iron oxide filler is in a form of particles such that cut end surfaces of the particles are exposed on the surface of the second through hole.
5. The inductor built-in substrate according to claim 1 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.
6. The inductor built-in substrate according to claim 1 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
7. The inductor built-in substrate according to claim 2 , wherein the magnetic resin includes iron oxide filler in an amount of 60% by weight or more.
8. The inductor built-in substrate according to claim 7 , wherein the iron oxide filler is in a form of particles such that cut end surfaces of the particles are exposed on the surface of the second through hole.
9. The inductor built-in substrate according to claim 2 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.
10. The inductor built-in substrate according to claim 2 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
11. The inductor built-in substrate according to claim 3 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.
12. The inductor built-in substrate according to claim 3 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
13. The inductor built-in substrate according to claim 4 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.
14. The inductor built-in substrate according to claim 4 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
15. The inductor built-in substrate according to claim 5 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
16. The inductor built-in substrate according to claim 9 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
17. The inductor built-in substrate according to claim 11 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
18. The inductor built-in substrate according to claim 7 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.
19. The inductor built-in substrate according to claim 7 , further comprising:
a plurality of conductor layers formed on sides of the core substrate respectively such that the conductor layers and the second through-hole conductor form a helical inductor.
20. The inductor built-in substrate according to claim 8 , wherein the core substrate is formed such that the surface of the first through hole has a ten-point average roughness Rz in a range of 2.3 to 12.3 μm, and the magnetic resin is formed such that the surface of the second through hole has a ten-point average roughness Rz in a range of 0.1 to 2.2 μm.