Terminal structure, printed wiring board, module substrate, and electronic device
View Patent ↗The present invention relates to a terminal structure and an electronic device having the terminal structure. The terminal structure includes: a terminal having: a conductor layer containing at least one metal selected from gold, silver, and copper; a first layer containing nickel and phosphorus, laid on the conductor layer; a second layer having a smaller atomic ratio of nickel to phosphorus than the first layer and containing Ni 3 P, laid on the first layer; and a third layer containing a first intermetallic compound of an Ni—Cu—Sn type, laid on the second layer; and a solder layer on the third layer of the terminal. A second intermetallic compound of an Ni—P—Sn type partly covers a surface of the second layer on the third layer side and a maximum thickness of the second intermetallic compound in a lamination direction is from 0.05 to 0.7 μm.
1. A terminal structure comprising:
a terminal having:
a conductor layer containing at least one metal selected from gold, silver, and copper;
a first layer containing nickel and phosphorus, laid on the conductor layer;
a second layer having a smaller atomic ratio of nickel to phosphorus than the first layer and containing Ni 3 P, laid on the first layer;
a third layer containing a first intermetallic compound of an Ni—Cu—Sn type, laid on the second layer; and
a solder layer on the third layer of the terminal,
wherein a second intermetallic compound of an Ni—P—Sn type partly covers discontinuously a surface of the second layer on the third layer side and a maximum thickness of the second intermetallic compound in a lamination direction is from 0.05 to 0.7 μm, and
wherein the second intermetallic compound is not in contact with the solder layer.
2. The terminal structure according to claim 1 , wherein in a cross section along the lamination direction, a linear coverage over the surface of the second layer by the second intermetallic compound is from 5 to 50%.
3. The terminal structure according to claim 2 , wherein in a cross section along the lamination direction, the second intermetallic compound has a convex shape protruding from the third layer toward the second layer.
4. The terminal structure according to claim 1 , wherein in a cross section along the lamination direction, the second intermetallic compound has a convex shape protruding from the third layer toward the second layer.
5. A printed wiring board comprising the terminal structure as set forth in claim 1 .
6. An electronic device on which at least one printed wiring board as set forth in claim 5 , and a module substrate comprising the terminal structure and an electronic instrument electrically connected to the conductor layer in the terminal structure, is mounted.
7. A module substrate comprising the terminal structure as set forth in claim 1 , and an electronic instrument electrically connected to the conductor layer in the terminal structure.