Terminal and method for manufacturing terminal

1. A terminal comprising a connecting portion to be connected to a connecting portion of a mating terminal, wherein

the connecting portion includes:

a portion of a base material including iron or an iron-based alloy and having a fine asperity on a surface of the portion of the base material;

a first layer formed on a surface of at least the portion of the base material included in the connecting portion and having a surface formed into a fine asperity pattern; and

a second layer formed on the surface of the first layer, wherein

the first layer is provided for connecting the base material and the second layer to each other, and has higher hardness than the second layer, and

the second layer is provided for enhancing conductivity and lubrication property.

2. The terminal according to claim 1 , wherein

the base material includes stainless steel,

the first layer includes nickel, and

the second layer includes any one of tin, silver, and gold.

3. The terminal according to claim 1 , wherein

the fine asperity extends in a direction orthogonal to a sliding direction of the connecting portion or in a direction intersecting the sliding direction of the connecting portion at an almost right angle.

4. The terminal according to claim 1 , wherein

the connecting portion of the terminal is a tab portion of a male terminal.

5. The terminal according to claim 1 , wherein the fine asperity extends in a direction at an angle of between 60 degrees to 120 degrees relative to a sliding direction of the connecting portion to be connected to a connecting portion of a mating terminal.

6. The terminal according to claim 1 , wherein the fine asperity extends in a direction at an angle of between 0 degrees to 180 degrees relative to a sliding direction of the connecting portion to be connected to a connecting portion of a mating terminal.

7. The terminal according to claim 1 , wherein the fine asperity comprises

projecting portions that extend in an elongated manner in a direction orthogonal to a surface of the connecting portion, and

recessed portions that extend in an elongated manner in the direction orthogonal to the surface of the connecting portion.

8. The terminal according to claim 1 , wherein the fine asperity comprises fine spot-like projecting portions that are spotted at random on the surface of the base material.

9. A method for manufacturing a terminal including a connecting portion to be connected to a connecting portion of a mating terminal, the method comprising:

roughening a surface of a portion of a base material including stainless steel and including the connecting portion to form a fine asperity;

forming a first layer including nickel at least on the surface of the portion of the base material including stainless steel, the first layer including a fine asperity pattern and including the connecting portion; and

forming a second layer including any one of tin, silver, and gold on the surface of the first layer which is formed at least on the surface of the portion including the connecting portion.

10. The method according to claim 9 , wherein

the first layer is integrally formed on the surface of the base material such that the first layer covers the surface of the portion of the base material

the second layer is integrally formed on a surface of the first layer such that the second layer covers the surface of the first layer.

11. The method according to claim 10 , wherein the second layer is formed on the first layer in an overlapping manner by plating.

12. The method according to claim 9 , wherein the roughening the surface comprises roughening the surface by grinding using a grindstone, by transferring a fine asperity formed on a surface of a roller used in rolling the base material, or by a chemical roughening method.

13. The method according to claim 9 , wherein the fine asperity extends in a direction orthogonal to a sliding direction of the connecting portion to be connected to a connecting portion of a mating terminal.

14. The method according to claim 9 , wherein the fine asperity extends in a direction at an angle of between 60 degrees to 120 degrees relative to a sliding direction of the connecting portion to be connected to a connecting portion of a mating terminal.

15. The method according to claim 9 , wherein the fine asperity extends in a direction at an angle of between 0 degrees to 180 degrees relative to a sliding direction of the connecting portion to be connected to a connecting portion of a mating terminal.

16. The method according to claim 9 , wherein the fine asperity is formed before the first layer is formed.

17. The method according to claim 9 , wherein the fine asperity comprises

projecting portions that extend in an elongated manner in a direction orthogonal to a surface of the connecting portion, and

recessed portions that extend in an elongated manner in the direction orthogonal to the surface of the connecting portion.

18. The method according to claim 17 , wherein the first nickel layer enters the inside of the recessed portions of the fine asperity, and covers the recessed portions and projecting portions.

19. The method according to claim 9 , wherein the fine asperity comprises fine spot-like projecting portions that are spotted at random on the surface of the base material.