CN117089838A - Layered plating stack for improved contact resistance in corrosive environments - Google Patents
Layered plating stack for improved contact resistance in corrosive environments Download PDFInfo
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- CN117089838A CN117089838A CN202310552605.0A CN202310552605A CN117089838A CN 117089838 A CN117089838 A CN 117089838A CN 202310552605 A CN202310552605 A CN 202310552605A CN 117089838 A CN117089838 A CN 117089838A
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- 238000007747 plating Methods 0.000 title claims abstract description 217
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 16
- 239000000758 substrate Substances 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 53
- 229910052763 palladium Inorganic materials 0.000 claims description 24
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 23
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 15
- 229910052709 silver Inorganic materials 0.000 claims description 15
- 239000004332 silver Substances 0.000 claims description 15
- 239000010931 gold Substances 0.000 claims description 13
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 10
- 229910052737 gold Inorganic materials 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- SWELZOZIOHGSPA-UHFFFAOYSA-N palladium silver Chemical compound [Pd].[Ag] SWELZOZIOHGSPA-UHFFFAOYSA-N 0.000 claims description 8
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 4
- 239000010970 precious metal Substances 0.000 abstract description 4
- 239000007864 aqueous solution Substances 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 208
- 239000000463 material Substances 0.000 description 28
- 238000012360 testing method Methods 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 4
- 230000013011 mating Effects 0.000 description 4
- 229910001020 Au alloy Inorganic materials 0.000 description 3
- 239000003353 gold alloy Substances 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 239000000356 contaminant Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- -1 but not limited to Chemical compound 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 239000002346 layers by function Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
A layered plating stack comprising: a bottom plating layer formed on the substrate; an intermediate plating layer; an outer plating layer; and at least one strike layer of noble metal. The precious metal of the strike layer is different from the metal of the intermediate plating layer. Upon exposure to an aqueous solution containing Cl 2 、NO 2 And SO 2 After 1 day or more, the layered plating stack with the strike layer maintains a contact resistance of less than 25 milliohms when tested under a load of at least about 30 grams. Upon exposure to a composition comprising H 2 S、Cl 2 、NO 2 And SO 2 After being tested under a load of at least about 30 grams and with a wipe of at least about 0.1mm, the layered plating stack with the strike layer maintains a contact resistance of less than 25 milliohms.
Description
Technical Field
The present invention relates to a layered plating stack for improved contact resistance in a corrosive environment. In particular, the present invention relates to strike layers comprising noble metals such as palladium to improve low level contact resistance after exposure to corrosive environments.
Background
It is known to use strike layers between two layers of material. The strike layer generally forms a very thin (typically less than 0.5 microns thick) layer, has high quality and has good adhesion to adjacent layers of different metals. If it is desired to plate a material having a desired property or attribute to another substrate material or another plating material, but the material having the desired property has inherently poor adhesion to the substrate material or other plating material, a strike layer may be deposited between the layers that is compatible with both the material having the desired property or attribute and the plating substrate material. An example of this is an electrolytic silver palladium material that has poor adhesion when applied directly to a nickel material, in which case a strike (e.g., a silver strike) may be used that has good adhesion to both.
In a corrosive environment, the impact of strike layers buried under the functional layer is not typically seen when the final plated article is exposed to the corrosive environment. Any effect of the strike layer on the corrosion performance of the final plated article is not desired.
Thus, when the final article is exposed to a corrosive environment, it would be beneficial to provide strike layers made of materials that enhance the contact resistance of the final article.
Disclosure of Invention
It is an object of the present invention to provide a strike layer for use between layers of plating material that enhances contact resistance when exposed to a corrosive environment.
The object of the present invention is to provide a layered plating stack with at least one precious metal strike layer that is better subjected to corrosion testing than a plating stack with a silver strike layer. The noble metal may be, but is not limited to, palladium. The low level contact resistance is maintained at a significantly lower level for the layered plating stack with the noble metal strike layer than for the layered plating stack with the silver strike layer. The results of the layered plating stack with noble metal strike layer were consistently better than those with silver strike layer during the period of exposure to the corrosive environment and at different normal loads and wiping distances.
Embodiments relate to a layered plating stack comprising: a bottom plating layer formed on the substrate; an intermediate plating layer; an outer plating layer; and at least one strike layer of noble metal. The precious metal of the strike layer is different from the metal of the intermediate plating layer. Upon exposure to a composition comprising H 2 S、Cl 2 、NO 2 And SO 2 After 1 day or more in a gaseous environment of one or more of (a) the layered plating stack maintains a contact resistance of less than about 25 milliohms (mohms) when tested at a load of at least about 30 grams.
Embodiments relate to a layered plating stack comprising: a bottom plating layer formed on the substrate; an intermediate plating layer; an outer plating layer; and at least one strike layer of noble metal. The precious metal of the strike layer is different from the metal of the intermediate plating layer. Upon exposure to a composition comprising H 2 S、Cl 2 、NO 2 And SO 2 After being tested under a load of at least about 30 grams and with a wiping of at least about 0.1mm, the layered plating stack maintains a contact resistance of less than about 25 milliohms.
The temperature of the environment may be maintained at 30+ -2 degrees Celsius, the relative humidity at 70% + -2, and the layered plating stack is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 Is a kind of medium.
Other features and advantages of the present invention will become apparent from the following more detailed description of the illustrative embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
Drawings
FIG. 1 is a schematic cross-sectional view of a first embodiment of an illustrative layer of plating material having an illustrative strike layer disposed between respective layers.
Fig. 2 is a schematic representation of a second embodiment of an illustrative layer of plating material having an illustrative strike layer disposed between respective layers.
Fig. 3 is a schematic representation of a third embodiment of an illustrative layer of plating material having two illustrative strike layers disposed between respective layers.
Fig. 4 is a schematic representation of a fourth embodiment of an illustrative layer of plating material having three illustrative strike layers disposed between respective layers.
Fig. 5 is a graphical representation of corrosion over time of a layered plating stack having an outer layer of gold, an intermediate plating layer of silver palladium, and an underlying plating layer of nickel with a palladium strike layer therebetween after exposure to a corrosive gaseous environment for 0, 2, and 5 days.
Fig. 6 is a graph illustrating the contact resistance versus normal load and the contact resistance versus wiping of the layered plating stack of fig. 5.
Fig. 7 is a graph illustrating contact resistance versus normal load for a layer plating stack having an outer layer of gold, an intermediate plating layer of silver, and an underlying plating layer of nickel with a palladium strike layer therebetween.
Fig. 8 is a graph illustrating contact resistance versus wiping of the layered plating stack of fig. 7.
Fig. 9 is a graph illustrating contact resistance versus normal load for a layer plating stack having an outer layer of gold, an intermediate plating layer of silver, and an underlying plating layer of nickel with a palladium strike layer therebetween.
Fig. 10 is a graph illustrating contact resistance versus wiping of the layered plating stack of fig. 9.
Detailed Description
The description of the illustrative embodiments in accordance with the principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of the embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended to facilitate the description and is not intended to limit the scope of the invention in any way. Relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "top," "bottom" and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless specifically so indicated. Unless specifically stated otherwise, terms such as "attached," "affixed," "connected," "coupled," "interconnected," and the like refer to a relationship wherein a structure is fixed or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships.
Furthermore, the features and advantages of the invention are described with reference to the preferred embodiments. Accordingly, the invention is expressly not limited to embodiments illustrating some possible non-limiting combinations of features, which may be present alone or in other combinations of features, the scope of the invention being defined by the appended claims.
Referring to fig. 1, a first exemplary layered plating stack 10 has a first or bottom plating layer 12, a second or intermediate plating layer 14, and a third or outer plating layer 16. The first or bottom plating layer 12 of the layered plating stack is formed on a substrate 18, such as, but not limited to, a metal layer.
In the illustrative embodiment, the bottom plating layer 12 is made of nickel (Ni) or a nickel alloy. In the illustrative embodiment, the thickness of the bottom plating layer 12 is about 0.5 μm to about 5.0 μm. However, other materials and thicknesses of the bottom plating layer 12 may be used.
The intermediate plating layer 14 is made of silver or a silver alloy, such as, but not limited to, silver palladium (AgPd). In the illustrative embodiment, the thickness of the intermediate plating layer 14 is about 0.5 μm to about 5.0 μm. However, other materials and thicknesses of intermediate plating layer 14 may be used.
The outer plating layer 16 is made of gold (Au) or gold alloy. In the illustrative embodiment, the thickness of the outer plating layer 16 is about 0.1 μm to about 0.3 μm. However, other materials and thicknesses of the outer plating layer 16 may be used.
In the embodiment shown in fig. 1, a plated strike or flash layer 20 is applied between the bottom plating layer 12 and the intermediate plating layer 14. In the illustrative embodiment, the intermediate plating layer 14 is made of silver palladium and the strike or flash layer 20 is made of palladium (Pd), however other types of noble metals may be used such as, but not limited to, rhenium, ruthenium, rhodium, osmium, iridium, platinum, and gold. The strike or flash layer 20 is made of a material that is different from the material of the plating layer 12 or the intermediate plating layer 14. In the illustrative embodiment, strike or flash layer 20 has a minimum thickness of about 0.01 μm. In various illustrative embodiments, strike layer 20 has a thickness of less than about 1.0 μm, less than about 0.5 μm, less than about 0.2 μm.
Strike or flash layer 20 provides a suitable bond between the underlying and intermediate plating layers 12, 14. Strike or flash layer 20 also minimizes diffusion between bottom plating layer 12 and intermediate plating layer 14. In addition, as discussed above, the layered plating stack with palladium strike layer 20 provides improved low level contact resistance when exposed to corrosive gaseous environments.
The layered plating stack 10 with strike or flash layer 20 may be tested according to relevant test conditions such as, but not limited to, corrosive mixed flow gas environment exposure, wherein the layered plating stack 10 is exposed to H 2 S、Cl 2 、NO 2 And SO 2 Various combinations of one or more of the following. For example, the layered plating stack 10 with strike or flash layer 20 as shown in FIG. 1 was tested using a class IIA mixed flow gas test environment according to the EIA, EIA-364TP-65B mixed flow gas test procedure (EIA, EIA-364TP-65B Mixed Flowing Gas Test Procedure for Electrical Connectors,Contacts and Sockets) for electrical connectors, contacts and sockets, wherein the temperature was maintained at 30+ -2 degrees Celsius, the relative humidity was 70% + -2, and the layered plating stack 10 was exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 Is a kind of medium. After 0, 2 and 5 days of exposure, the appearance and low level contact resistance properties of the samples were recorded. The results are shown graphically in fig. 5 and graphically in fig. 6.
FIG. 5 shows the results of gold flash plating with palladium strike layer/1.4 μm silver palladium/nickel stack. Results are shown after test exposures of 0, 2 and 5 days.
As shown in fig. 6, upon exposure to a temperature maintained at 30±2 degrees celsius and a relative humidity of 70% ±2, and the layered plating stack 10 is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 After 1 day or more in an environment of at least about 30 grams, the layered plating stack with strike layer 20 maintains a contact resistance of less than about 25 milliohms (mohms) and typically less than about 10 milliohms.
As shown in fig. 6, upon exposure to a temperature maintained at 30±2 degrees celsius and a relative humidity of 70% ±2, and the layered plating stack 10 is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 The layered plating stack 10 with strike layer 20 maintains a contact resistance of less than about 25 milliohms and typically less than about 10 milliohms when tested under a load of at least about 30 grams and with a wipe of about 0.1mm or greater. Wiping refers to sliding or tangential movement between the top surface of the layered plating stack 10 and the surface of the mating contact as the mating contact moves into engagement with the layered plating stack 10. The wiping motion allows for removal of oxides and other contaminants present on the surface.
As shown in fig. 6, the layered plating stack with palladium strike layer 20 was better subjected to corrosion testing than the plating stack with silver strike layer. As shown in fig. 6, the low level contact resistance is maintained at a significantly lower level for the layered plating stack with the palladium strike layer than for the layered plating stack with the silver strike layer. Over time and at different normal loads and wiping distances, the results of the layered plating stack with palladium strike layer are always better than the layered plating stack with silver strike layer.
In another illustrative embodiment, the bottom plating layer 12 is made of nickel, the middle plating layer 14 is made of silver, and the outer plating layer is made of gold. A strike or flash layer 20 is applied between the bottom layer of plating 12 and the middle layer of plating 14. In this illustrative embodiment, strike or flash layer 20 is made of palladium (Pd). In the illustrative embodiment, strike or flash layer 20 has a minimum thickness of about 0.01 μm. In various illustrative embodiments, the strike or flash layer 20 has a thickness of less than about 1.0 μm, less than about 0.5 μm, less than about 0.2 μm.
As previously described, the layered plating stack 10 with strike or flash layer 20 may be tested according to relevant test conditions such as, but not limited to, corrosive mixed flow gas environment exposure, wherein the layered plating stack 10 is exposed to H 2 S、Cl 2 、NO 2 And SO 2 Various combinations of one or more of the following. For example, the layered plating stack 10 with the silver intermediate plating layer 14 and the palladium strike or flash layer 20 was tested according to the EIA, EIA-364TP-65B mixed flow gas test procedure for electrical connectors, contacts and sockets using a class IIA mixed flow gas test environment in which the temperature was maintained at 30±2 degrees celsius and the relative humidity was 70% ±2, and the layered plating stack 10 was exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 Is a kind of medium. After 0, 2 and 5 days of exposure, the appearance and low level contact resistance properties of the samples were recorded.
As shown in fig. 7 and 8, in which the palladium strike or flash layer 20 is about 1.5 μm, and fig. 9 and 10, in which the palladium strike or flash layer 20 is about 4.5 μm, upon exposure to a temperature maintained at 30±2 degrees celsius and a relative humidity of 70% ±2, and the layered plating stack 10 is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 After 1 day or more in the environment of (a), when tested under a load of at least about 30 grams, as described in the preceding paragraphThe layered plating stack maintains a contact resistance of less than about 25 milliohms and typically less than about 10 milliohms. In addition, the layered plating stack 10 is exposed to 10+0/-4ppb H upon exposure wherein the temperature is maintained at 30+ -2 degrees Celsius and the relative humidity is 70% + -2 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 The layered plating stack 10 with strike layer 20 maintains a contact resistance of less than about 25 milliohms and typically less than about 10 milliohms when tested under a load of at least about 30 grams and with a wipe of about 0.1mm or greater. Wiping refers to sliding or tangential movement between the top surface of the layered plating stack 10 and the surface of the mating contact as the mating contact moves into engagement with the layered plating stack 10. The wiping motion allows for removal of oxides and other contaminants present on the surface.
The layered plating stack with palladium strike or flash layer 20 described above and depicted in fig. 7-10 is better subjected to corrosion testing than the plating stack with silver strike layer. Over time and at different normal loads and wiping distances, the results of the layered plating stack with palladium strike layer are always better than the layered plating stack with silver strike layer.
Referring to fig. 2, a second exemplary layered plating stack 110 has a first or bottom plating layer 112, a second or intermediate plating layer 114, and a third or outer plating layer 116. The first or bottom plating layer 112 of the layered plating stack is formed on a substrate 118, such as, but not limited to, a metal layer.
In the illustrative embodiment, the bottom plating layer 112 is made of nickel (Ni) or a nickel alloy. In the illustrative embodiment, the thickness of the bottom plating layer 112 is about 0.5 μm to about 1.25 μm. However, other materials and thicknesses of the bottom plating layer 112 may be used.
The intermediate plating layer 114 is made of silver palladium (AgPd). In an illustrative embodiment, the thickness of the intermediate plating layer 114 is about 0.7 μm to about 1.0 μm. However, other materials and thicknesses of the intermediate plating layer 114 may be used.
The outer plating layer 116 is made of gold (Au) or gold alloy. In the illustrative embodiment, the thickness of the outer plating layer 116 is about 0.1 μm to about 0.3 μm. However, other materials and thicknesses of the outer plating layer 116 may be used.
In the embodiment shown in fig. 2, a plating strike layer 120 is applied between the intermediate plating layer 114 and the outer layer 116. In the illustrative embodiment, strike layer 120 is made of palladium (Pd), however other types of noble metals may be used. In the illustrative embodiment, strike layer 120 has a minimum thickness of 0.01 μm. In various illustrative embodiments, strike layer 120 has a thickness of less than about 1.0 μm, less than about 0.5 μm, less than about 0.2 μm.
Strike layer 120 provides a suitable bond between intermediate plating layer 114 and outer layer 116. Strike layer 120 also minimizes diffusion between intermediate plating layer 114 and outer layer 116. In addition, as discussed above, the layered plating stack with palladium strike layer 120 provides improved low level contact resistance when exposed to corrosive gaseous environments.
Referring to fig. 3, a third exemplary layered plating stack 210 has a first or bottom plating layer 212, a second or intermediate plating layer 214, and a third or outer plating layer 216. A first or bottom plating layer 212 of a layered plating stack is formed on a substrate 218, such as, but not limited to, a metal layer.
In the illustrative embodiment, the bottom plating layer 212 is made of nickel (Ni) or a nickel alloy. In the illustrative embodiment, the thickness of the bottom plating layer 212 is about 0.5 μm to about 1.25 μm. However, other materials and thicknesses of the bottom plating layer 212 may be used.
The intermediate plating layer 214 is made of silver palladium (AgPd). In the illustrative embodiment, the thickness of intermediate plating layer 214 is about 0.7 μm to about 1.0 μm. However, other materials and thicknesses of intermediate plating layer 214 may be used.
The outer plating layer 216 is made of gold (Au) or gold alloy. In the illustrative embodiment, the thickness of the outer plating layer 216 is about 0.1 μm to about 0.3 μm. However, other materials and thicknesses of the outer plating layer 216 may be used.
In the embodiment shown in fig. 3, a first plating strike layer 220 is applied between the bottom plating layer 212 and the intermediate plating layer 214, and a second plating strike layer 221 is applied between the intermediate plating layer 214 and the outer layer 216. In the illustrative embodiment, strike layers 220, 221 are made of palladium (Pd), however other types of noble metals may be used. In the illustrative embodiment, strike layers 220, 221 have a minimum thickness of 0.01 μm. In various illustrative embodiments, strike layers 220, 221 have a thickness of less than about 1.0 μm, less than about 0.5 μm, less than about 0.2 μm.
Strike layers 220, 221 are provided to provide a suitable bond between bottom plating layer 212 and intermediate plating layer 214 and between intermediate plating layer 214 and outer layer 216. Strike layers 220, 221 may also minimize diffusion between bottom plating layer 212 and intermediate plating layer 214 and between intermediate plating layer 214 and outer layer 216. In addition, as discussed above, the layered plating stack with palladium strike layers 220, 221 provides improved low level contact resistance after exposure to a corrosive gaseous environment.
The embodiment shown in fig. 4 is similar to the embodiment shown in fig. 3 except that an additional plate strike layer 323 is provided. Applying a first plating strike layer 320 between the bottom plating layer 212 and the middle plating layer 214; applying a second plated strike layer 321 between the intermediate plating layer 214 and the outer layer 216; and a third strike layer 323 is applied between the underlying plating layer 212 and the substrate 218.
In the illustrative embodiment, strike layers 320, 321, 323 are made of palladium (Pd), however other types of noble metals may be used. In the illustrative embodiment, strike layers 320, 321, 323 have a minimum thickness of 0.01 μm. In various illustrative embodiments, strike layers 320, 321, 323 are less than about 1.0 μm thick, less than about 0.5 μm thick, less than about 0.2 μm thick.
Strike layers 320, 321, 323 are provided to provide proper bonding between bottom plating layer 212 and intermediate plating layer 214, intermediate plating layer 214 and outer layer 216, and bottom plating layer 212 and substrate 218. Strike layers 320, 321, 323 may also minimize diffusion between bottom plating layer 212 and intermediate plating layer 214, intermediate plating layer 214 and outer layer 216, and bottom plating layer 212 and substrate 218. In addition, as discussed above, the plating stack with palladium strike layers 320, 321, 323 provides improved low level contact resistance after exposure to a corrosive gaseous environment.
If the strike layer 20, 120, 220, 221, 320, 321, 323 has a thickness of less than about 0.01 μm, the strike layer 20, 120, 220, 221, 320, 321, 323 does not adequately cover the underlying plating layer 12, 212; intermediate layers 114, 214 or a substrate 218. On the other hand, if the thickness of the strike layer 20, 120, 220, 221, 320, 321, 323 is greater than about 1.0 μm, the quality improvement effect due to the increase in thickness is negligible, and only the product cost is increased.
Claims (15)
1. A layered plating stack comprising:
a bottom plating layer formed on the substrate;
an intermediate plating layer;
an outer plating layer; and
at least one strike layer of noble metal, the noble metal of the strike layer being different from the metal of the intermediate plating layer;
wherein, upon exposure to a composition comprising H 2 S、Cl 2 、NO 2 And SO 2 After 1 day or more in a gaseous environment of one or more of (a) and (b) when tested at a load of at least about 30 grams, the layered plating stack maintains a contact resistance of less than 25 milliohms.
2. The layered plating stack of claim 1 wherein upon exposure to a metal comprising H 2 S、Cl 2 、NO 2 And SO 2 After 1 day or more in a gaseous environment of one or more of (a) and (b) when tested at a load of at least about 30 grams, the layered plating stack maintains a contact resistance of less than 10 milliohms.
3. The layered plating stack of claim 1 wherein the temperature of the gaseous environment is maintained at 30±2 degrees celsius, the relative humidity is 70% ±2, and the layered plating stack is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 。
4. The layered plating stack according to claim 1, wherein the at least one strike layer has a minimum thickness of about 0.01 μιη, preferably wherein the at least one strike layer has a thickness of less than about 1.0 μιη.
5. The layered plating stack according to claim 1, wherein the noble metal is palladium.
6. The layered plating stack of claim 1, wherein the at least one plating strike layer is applied between the bottom plating layer and the intermediate plating layer, or wherein the at least one plating strike layer is applied between the intermediate plating layer and the outer plating layer.
7. The layered plating stack according to claim 1, wherein the at least one plating strike layer is a first strike layer applied between the bottom plating layer and the middle plating layer, and a second strike layer is applied between the middle plating layer and the outer plating layer.
8. The layered plating stack according to claim 1, wherein the bottom plating layer comprises nickel or a nickel alloy.
9. The layered plating stack according to claim 1, wherein the thickness of the underlying plating layer is from about 0.5 μm to about 5.0 μm.
10. The layered plating stack according to claim 1, wherein the intermediate plating layer comprises silver palladium or silver.
11. The layered plating stack according to claim 1, wherein the thickness of the intermediate plating layer is about 0.5 μm to about 5.0 μm, preferably wherein the thickness of the outer plating layer is about 0.1 μm to about 0.3 μm.
12. The layered plating stack according to claim 1, wherein the outer plating layer comprises gold.
13. A layered plating stack comprising:
a bottom plating layer formed on the substrate;
an intermediate plating layer;
an outer plating layer; and
at least one strike layer of noble metal, the noble metal of the strike layer being different from the metal of the intermediate plating layer;
wherein, upon exposure to a composition comprising H 2 S、Cl 2 、NO 2 And SO 2 After being tested under a load of at least about 30 grams and with a wiping of at least about 0.1mm, the layered plating stack maintains a contact resistance of less than 25 milliohms.
14. The layered plating stack of claim 13 wherein upon exposure to a metal comprising H 2 S、Cl 2 、NO 2 And SO 2 After being tested under a load of at least about 30 grams and with a wiping of at least about 0.1mm, the layered plating stack maintains a contact resistance of less than 10 milliohms.
15. The layered plating stack of claim 13 wherein the temperature of the environment is maintained at 30±2 degrees celsius, the relative humidity is 70% ±2, and the layered plating stack is exposed to 10+0/-4ppb H 2 S、10+0/-2ppb Cl 2 、200±25ppb NO 2 And 100+ -25 ppb SO 2 。
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63/343,677 | 2022-05-19 | ||
| US18/314,279 US20230374688A1 (en) | 2022-05-19 | 2023-05-09 | Layered Plating Stack for Improved Contact Resistance in Corrosive Environments |
| US18/314,279 | 2023-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117089838A true CN117089838A (en) | 2023-11-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310552605.0A Pending CN117089838A (en) | 2022-05-19 | 2023-05-16 | Layered plating stack for improved contact resistance in corrosive environments |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117089838A (en) |
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2023
- 2023-05-16 CN CN202310552605.0A patent/CN117089838A/en active Pending
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