Inductor

1. An inductor comprising:

a main body having a bottom surface, a top surface positioned opposite to the bottom surface, four side surfaces connected to the bottom surface and the top surface;

a metal body that includes a first metal portion buried in the main body and second metal portions extending outward from respective opposite longitudinal ends of the first metal portion, the second metal portions being exposed from respective opposite side surfaces of the main body, wherein

each of the second metal portion being a plate-like shape has a first surface with a plating layer and a second surface opposite to the first surface,

each of the second metal portion defines an external terminal, includes a first bend that is formed by bending the second metal portion such that the second surface opposes a corresponding one of the opposite side surfaces of the main body, and includes a second bend that is formed by bending the second metal portion such that the second surface opposes the bottom surface of the main body,

when R1 denotes a curvature radius of an inner peripheral surface of the second bend, t denotes a thickness of each second metal portion at the second bend, and λ denotes a value determined based on the ratio R1 to t, such that λ is 0.3 in a case of R1/t being less than 0.5, or λ is 0.35 in a case of R1/t being in the range of 0.5 to less than 1.5, or λ is 0.43 in a case of R1/t being in the range of 1.5 to less than 3.0, or λ is 0.5 in a case of R1/t being 5.0 or more,

a curvature radius R2 of a neutral surface of bending of the second bend is obtained from an equation R2=R1+λ×t, and

a curvature radius R3 of an outer peripheral surface of the second bend is obtained from an equation R3=R1+t,

when a first distance A is defined as a distance between an end of the first bend that is closer to a tip of each second metal portion and an end of the second bend that is closer to the first metal portion, and when a second distance B is defined as a distance between the tip of each second metal portion and an end of the second bend that is closer to the tip of each second metal portion,

a length of the neutral surface is obtained by A+B+R2×2×π×90°/360°, and

a total length of the first distance A, the second distance B, and the outer peripheral surface of the second bend is obtained by A+B+R3×2×π×90°/360°, and

when an elongation percentage ε of the outer peripheral surface is defined as {(the length of the outer peripheral surface−the length of the neutral surface)/the length of the outer peripheral surface}×100, the first distance A is set to be shorter than a height of the corresponding one of the side surfaces of the main body, and the second distance B is set to be shorter than a half of a distance between the opposite side surfaces of the main body,

the elongation percentage ε of the outer peripheral surface is 13% or less.

2. The inductor according to claim 1 , wherein

the plating layer includes a first layer of nickel plating formed on a surface of a base metal made of copper and a second layer of tin plating formed on the first layer.

3. The inductor according to claim 1 , wherein

the first metal portion having a plate-like shape has a first surface with a plating layer and a second surface opposite to the first surface,

the first metal portion is buried in the main body such that the second surface is substantially parallel to the bottom surface of the main body, and

the plating layer is disposed at an opposite side to the bottom surface of the main body.

4. The inductor according to claim 1 , wherein

the first metal portion is shaped like a coil having one or more turns.

5. The inductor according to claim 3 , wherein

a lateral length of each second metal portion at the first bend is substantially the same as a lateral length of the first metal portion,

a lateral length of each second metal portion at a position other than the first bend is longer than the lateral length of the first metal portion, and

the lateral length of each second metal portion at a position other than the first bend is substantially the same as or smaller than a lateral length of the main body.

6. The inductor according to claim 5 , wherein

the main body has an approximate size of 2.5 mm by 2.0 mm by 1.0 mm.

7. The inductor according to claim 2 , wherein

the first metal portion having a plate-like shape has a first surface with a plating layer and a second surface opposite to the first surface,

the first metal portion is buried in the main body such that the second surface is substantially parallel to the bottom surface of the main body, and

the plating layer is disposed at an opposite side to the bottom surface of the main body.

8. The inductor according to claim 7 , wherein

a lateral length of each second metal portion at the first bend is substantially the same as a lateral length of the first metal portion,

a lateral length of each second metal portion at a position other than the first bend is longer than the lateral length of the first metal portion, and

the lateral length of each second metal portion at a position other than the first bend is substantially the same as or smaller than a lateral length of the main body.

9. The inductor according to claim 8 , wherein

the main body has an approximate size of 2.5 mm by 2.0 mm by 1.0 mm.

10. The inductor according to claim 2 , wherein

the first metal portion is shaped like a coil having one or more turns.