Powder magnetic core with terminal and method for manufacturing the same

1. A powder magnetic core with terminal comprising:

a powder magnetic core composed of Fe-based alloy particles including Fe and an element M (M is at least one of Cr or Al) which is more easily oxidizable than Fe; and

at least two terminals formed at an interval on a surface of the powder magnetic core,

wherein,

the powder magnetic core includes

the Fe-based alloy particles, and

an underlayer including the element M (M is at least one of Cr or Al), Fe and O formed on a surface of the Fe-based alloy particles;

a first layer consisting essentially of at least one of Cr or Al and O, and the first layer being essentially free of Fe, is formed on a surface including a region in which the terminals of the powder magnetic core are formed;

the terminals are formed on a surface of the first layer; and

each of the terminals includes a second layer including one of Au, Ag, Cu, Ti or Cr.

2. The powder magnetic core with terminal according to claim 1 , wherein the terminal further includes a third layer including one of Ni, Au, Ag or Sn formed on a surface of the second layer.

3. The powder magnetic core with terminal of claim 1 , wherein a thickness tu of the underlayer, a thickness t1 of the first layer, and a thickness t2 of the second layer have a relationship of tu<t1<t2.

4. The powder magnetic core with terminal according to claim 1 , wherein the first layer is composed of a Cr oxide or an Al oxide.

5. The powder magnetic core with terminal according to claim 1 ,

wherein:

the Fe-based alloy includes Fe, Al and Cr;

the underlayer includes Fe, Al, Cr and O; and

the first layer consists essentially of Al or Cr and O.

6. The powder magnetic core with terminal according to claim 1 ,

wherein:

two terminals are formed side by side on one surface of the powder magnetic core; and

the underlayer is formed on the entire one surface of the powder magnetic core including at least between the terminals.

7. A method for manufacturing a powder magnetic core with terminal according to claim 1 ,

the method comprising:

producing the powder magnetic core including an underlayer formed on a surface of the Fe-based alloy particles, the underlayer including the element M (M is at least one of Cr or Al), and Fe and O;

forming a first layer consisting essentially of at least one of Cr or Al and O, and the first layer being essentially free of Fe, on a surface including a region in which the terminals of the powder magnetic core are formed; and

forming a second layer including one of Au, Ag, Cu, Ti, Fe or Cr on a surface of the first layer,

wherein the first layer and the second layer are each formed by a sputtering method or a vapor deposition method.

8. The method for manufacturing a powder magnetic core with terminal of claim 7 , further comprising forming a third layer including one of Ni, Au, Ag or Sn on a surface of the second layer.

9. The method for manufacturing a powder magnetic core with terminal according to claim 7 ,

wherein the first layer is composed of a Cr oxide or an Al oxide.

10. The method for manufacturing a powder magnetic core with terminal according to claim 7 , further comprising:

pressing a mixed powder including the Fe-based alloy particles into a predetermined shape to obtain a green compact; and

heat-treating the green compact obtained by the pressing in an oxygen-containing atmosphere to oxidize the Fe-based alloy particles at high temperature, thereby forming the underlayer on the surface of the Fe-based alloy particles.

11. The method for manufacturing a powder magnetic core with terminal according to claim 7 ,

wherein:

a thickness of the underlayer is 50 nm or more and 100 nm or less;

a thickness of the first layer is more than 50 nm; and

a total thickness of the underlayer and the first layer is 150 nm or more.