Silver-tin coating for electrical connectors, and electrical connectors with siliver-tin coatings
View Patent ↗A copper alloy electrical connector component has a coating thereon formed by applying a nickel layer of between about 5 μin and about 20 μin over the copper alloy; applying a copper layer of between about 7 μin and about 18 μin over the nickel layer; applying a total of between about 5 μin and about 15 μin silver layers and about 40 μin and about 80 μin of tin layers over the copper layer: and heating to the coated copper alloy electrical connector component to cause mixing of the silver and tin layers and formation of at least 8 vol % of an Ag3Sn intermetallic.
1 . A copper alloy electrical connector component having a coating thereon comprising a nickel layer of between about 5 μin and about 20 μin over the copper alloy;
applying a copper layer of between about 7 μin and about 18 μin over the nickel layer; a total of between about 5 μin and about 15 μin of one or more silver layers and a total of between about 40 μin and about 80 μin of one or more tin layers over the copper layer, wherein subsequent reflow heating of the connector will cause mixing of the silver and tin layers and formation of between about 8 vol % and about 45 vol % of an Ag 3 Sn intermetallic.
2 . The copper alloy electrical connector component according to claim 1 wherein the one or more silver layers are applied as a single layer over the copper layer, and the one or more tin layers are applied as a single layer over the silver layer.
3 . The copper alloy electrical connector component according to claim 1 wherein the one or more silver layers and the one or more tin layers are applied as a plurality of alternating layers of silver and of tin.
4 . The copper alloy electrical connector component according to claim 1 wherein after reflow heating the coating gives the connector component an R/N of between about 0.20 and about 0.13.
5 . The copper alloy electrical connector component according to claim 4 wherein after reflow heating the coating gives the connector component an R/N of between about 0.19 and about 0.135.
6 . The copper alloy electrical connector component according to claim 1 wherein there is a total of between about 5 μin and about 10 μin of one or more silver layers.
7 . A copper alloy electrical connector component having a coating thereon formed by applying a nickel layer of between about 5 μin and about 20 μin over the copper alloy; applying a copper layer of between about 7 μin and about 18 μin over the nickel layer; applying a silver layer of between 5 μin and about 15 μin; and applying between about 40 μin and about 80 μin of tin; and reflow heating the coated copper alloy electrical connector component to cause mixing of the silver and tin layers and formation of a silver tin layer including between about 8 vol % and about 45 vol % of an Ag 3 Sn intermetallic.
8 . The copper alloy electrical connector component according to claim 7 wherein the coating gives the connector component an R/N of between about 0.20 and about 0.13.
9 . The copper alloy electrical connector component according to claim 8 wherein after reflow heating the coating gives the connector component an R/N of between about 0.19 and about 0.135.
10 . The copper alloy electrical connector component according to claim 7 wherein there is a total of between about 5 μin and about 10 μin of one or more silver layers applied before reflow heating.
11 . A coating over a copper alloy electrical connector component, the coating formed by applying a nickel layer of between about 5 μin and about 20 μin over the copper alloy; applying a copper layer of between about 7 μin and about 18 μin over the nickel layer; applying a total of between 5 μin and about 15 μin silver layers and about 40 μin and about 80 μin of tin layers over the copper layer; and reflow heating the coated copper alloy electrical connector component to cause mixing of the silver and tin layers and formation of a silver tin layer including between 8 vol % and 45 vol % of an Ag 3 Sn intermetallic.
12 . The coating on a copper alloy electrical connector component according to claim 11 wherein the coating gives the connector component an R/N of between about 0.20 and about 0.13.
13 . The coating on a copper alloy electrical connector component according to claim 12 wherein after reflow heating the coating gives the connector component an R/N of between about 0.19 and about 0.135.
14 . The coating on a copper alloy electrical connector component according to claim 11 wherein there is a total of between about 5 μin and about 10 μin of one or more silver layers applied before reflow heating.
15 . A method of forming a coating on a copper alloy electrical connector component, the method comprising:
applying a nickel layer of between about 5 μin and about 20 μin over the copper alloy; applying a copper layer of between about 7 μin and about 18 μin over the nickel layer; applying a total of between about 5 μin and about 15 μin of silver layers and about 40 μin and about 80 μin of tin layers over the copper layer; and reflow heating the coating to cause mixing of the silver and tin layers and formation of between 8 vol % and about 45 vol % of an Ag 3 Sn intermetallic in the resulting silver tin layer.
16 . The method according to claim 15 wherein the silver layers are applied as a single layer over the copper layer, and the tin layers are applied as a single layer over the silver layer.
17 . The method according to claim 15 wherein the silver layers and the tin layers are applied as a plurality of alternating layers of silver and of tin.
18 . The method according to claim 15 wherein the coating gives the connector component an R/N of between about 0.20 and about 0.13.
19 . The method according to claim 18 wherein after reflow heating the coating gives the connector component an R/N of between about 0.19 and about 0.135.
20 . The method according to claim 18 wherein there is a total of between about 5 μin and about 10 μin of one or more silver layers applied before reflow heating.
21 . A copper alloy electrical connector component according to claim 7 wherein the silver layer is disposed between the copper layer and the tin.
22 . A coating over a copper alloy electrical connector component according to claim 11 , wherein at least one of said silver layers is disposed between the copper layer and one of the tin layers.
23 . A coating over a copper alloy electrical connector component according to claim 11 , wherein the layers of silver and the layers of tin are interleaved over the copper layer.