Patent Publication Number: US-2015079421-A1

Title: Electrical component and method for fabricating same

Description:
BACKGROUND OF THE INVENTION 
     The subject matter described and/or illustrated herein relates generally to electrical components, and more particularly to electrical components having nickel and silver layers. 
     Electrical components are used to provide electrical pathways between various components for a variety of applications. Electrical contacts, electrical traces, electrical vias, electrical wires, and the like are examples of electrical components that provide electrical pathways. At least some known electrical components include an interior layer of nickel and a layer of silver that extends over the nickel layer. But, silver and nickel have little or no mutual solubility or reaction with each other, such that the nickel and silver layers do not readily interdiffuse and form a relatively strong bond. Moreover, oxygen readily diffuses through silver. If enough oxygen gets to the interface between the nickel and silver layers, the resulting oxide layer that forms at the nickel/silver interface may weaken the bond between the nickel and silver layers, which may cause the silver layer to delaminate from the nickel layer. Delamination of the silver layer is not limited to electrical components having interior layers of nickel (i.e., is not limited to silver and nickel interfaces). Rather, oxidation may cause a silver layer to delaminate from interior layers fabricated from other materials (e.g., an interface between a silver layer and an interior layer of copper and/or another material). 
     It is known to use a minimal strike layer (e.g., acid silver strike) between the nickel and silver layers to enhance the adhesion between the nickel and silver layers. Such a strike layer can facilitate preventing the silver layer from delaminating at temperatures below approximately 150° C. But, at least some known electrical components are used in applications where the electrical component is exposed to temperatures greater than approximately 150° C. For example, electrical components may be used in automotive and/or aerospace applications wherein the environment (e.g., an engine compartment) of the electrical component is exposed to temperatures greater than approximately 150° C. But, the silver layer may delaminate from the nickel layer when the electrical component is exposed to temperatures greater than approximately 150° C. For example, at temperatures greater than approximately 150° C., the adhesion between the nickel and silver layers may be degraded enough to lead to delamination caused by the formation of a nickel oxide layer at the interface between the silver and nickel layers. Accordingly, the silver layers of at least some known electrical components may delaminate when the electrical component is exposed to temperatures greater than approximately 150° C. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In an embodiment, an electrical component includes an interior layer that an exterior surface. The electrical component includes an intermediate layer that includes at least one platinum group metal (PGM). The intermediate layer extends on the exterior surface of the interior layer. The intermediate layer has an exterior PGM surface. The electrical component includes a silver layer that includes silver. The silver layer extends on the exterior PGM surface such that the intermediate layer extends between the interior layer and the silver layer. 
     In an embodiment, a method is provided for fabricating an electrical component. The method includes depositing an intermediate layer on an exterior surface of an interior layer of the electrical component. The intermediate layer includes at least one platinum group metal (PGM) and has an exterior PGM surface. The method includes depositing a silver layer on the exterior PGM surface of the intermediate layer such that the intermediate layer extends between the interior layer and the silver layer. The silver layer is fabricated at least partially from silver. 
     In an embodiment, an electrical component includes an interior layer that includes an exterior surface. An intermediate layer extends on the exterior surface of the interior layer. The intermediate layer has an exterior PGM surface. The electrical component includes a silver layer that includes silver. The silver layer extends on the exterior PGM surface such that the intermediate layer extends between the interior layer and the silver layer. The intermediate layer is fabricated from at least one material that does not oxidize such that the intermediate layer provides a barrier that prevents an oxide layer from forming on the exterior surface of the interior layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of an electrical contact. 
         FIG. 2  is a cross-sectional view of the electrical contact shown in  FIG. 1  taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of another embodiment of an electrical contact. 
         FIG. 4  is a flowchart illustrating an embodiment of a method for fabricating an electrical contact. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an embodiment of an electrical component  10 . In the illustrated embodiment, the electrical component  10  is an electrical contact (i.e., an electrical terminal) that is configured to mate with a complementary electrical contact (not shown). But, the electrical component  10  is not limited to being an electrical contact. Rather, the electrical component  10  may be any other type of electrical component that provides an electrical pathway, such as, but not limited to, an electrical trace, an electrical via, an electrical wire, an electrical contact pad (i.e., a surface mount electrical contact), and/or the like. The electrical component  10  will be referred to throughout the remainder of the DETAILED DESCRIPTION OF THE INVENTION as an “electrical contact”  10 . 
     The electrical contact  10  extends from a mating segment  12  to a mounting segment  14 . The electrical contact  10  is configured to be mated with the complementary electrical contact at the mating segment  12 . The mounting segment  14  of the electrical contact  10  is configured to be mounted to a substrate (not shown; e.g., a circuit board and/or the like), terminated to an electrical wire (not shown; whether or not the electrical wire is grouped in a cable with one or more other electrical wires), and/or mounted to another structure. 
     In the illustrated embodiment of  FIG. 1 , the mating segment  12  is a pin that is configured to be received within a socket of the complementary electrical contact. But, the electrical contact  10  is not limited to the specific embodiment of the mating segment  12  described and/or illustrated herein. Rather, the pin of the mating segment  12  is meant as exemplary only. For example, in other embodiments, the mating segment  12  may be socket that is configured to receive a pin of the complementary electrical contact  10  therein. In still other embodiments, and for example, the mating interface  12  of the electrical contact  10  may include another structure, such as, but not limited to, a blade structure, a spring finger structure, another spring structure, and/or the like. 
     The mounting segment  14  of the electrical contact  10  is a crimp barrel in the illustrated embodiment of  FIG. 1 . The crimp barrel of the mounting segment  14  is configured to be crimped around the end of an electrical wire (not shown). But, the electrical contact  10  is not limited to the specific embodiment of the mounting segment  14  that is described and/or illustrated herein. Rather, the crimp barrel of the mounting segment  14  is meant as exemplary only. For example, in other embodiments, the mounting segment  14  may have a different crimp structure than the crimp barrel. Moreover, and for example, the mounting segment  14  may include a solder tail, a surface mount structure, a spring structure, a press-fit pin (e.g., an eye-of-the needle pin and/or the like), a solder interface, a weld interface, and/or the like. 
     Although shown as extending along an approximately straight path between the mating segment  12  and the mounting segment  14 , the electrical contact  10  may have another shape. For example, the electrical contact  10  may include one or more bends (not shown) such that the path of the electrical contact  10  between the mating and mounting segments  12  and  14 , respectively, is not approximately straight. One specific example of another shape of the electrical contact  10  is an electrical contact that has an approximately 90° bend between the mating segment  12  and the mounting segment  14  such that the electrical contact  10  is a right-angle contact. 
     The electrical contact  10  may be configured to conduct electrical data signals, electrical power, or electrical ground. Moreover, the electrical contact  10  may be used in any application, within any type of electrical connector (not shown), and/or the like. Examples of suitable applications of the electrical contact  10  are automotive applications, aerospace applications, electrical power generation and/or distribution applications, communication applications, and/or the like. In some embodiments, the electrical contact  10  is used in an application where the electrical contact  10  is exposed to temperatures greater than approximately 150° C. For example, the electrical contact  10  may be used in automotive and/or aerospace applications wherein the environment (e.g., an engine compartment and/or the like) of the electrical contact  10  is exposed to temperatures greater than approximately 150° C. 
       FIG. 2  is a cross-sectional view of the electrical contact  10  taken along line  2 - 2  of  FIG. 1 . At least a portion of the electrical contact  10  includes a layered structure  16  having a base  18 , an interior layer  20 , an intermediate layer  22 , and a silver (Ag) layer  24 . As will be described below, the intermediate layer  22  extends between the interior layer  20  and the silver layer  24  and is fabricated from at least one material that does not oxidize such that the intermediate layer  22  prevents a reaction layer (e.g., an oxide layer) from forming on the interior layer  20 . 
     As should be apparent from line  2 - 2  of  FIG. 1 , in the illustrated embodiment of  FIGS. 1 and 2 , the layered structure  16  of the electrical contact  10  defines at least a portion of the mating segment  12  of the electrical contact  10 . The layered structure  16  may define any amount of the mating segment  12  and may define any location(s) along the mating segment  12 . In the illustrated embodiment of  FIGS. 1 and 2 , the layered structure  16  defines an approximate entirety of the mating segment  12 . 
     In some embodiments, and in addition or alternative to at least a portion of the mating segment  12  being defined by the layered structure  16 , one or more other portions (e.g., the mounting segment  14 ) of the electrical contact  10  is at least partially defined by the layered structure  16 . Any amount of, and any location(s) along, such other portion(s) of the electrical contact  10  may be defined by the layered structure  16 . 
     Although shown as having a circular cross-sectional shape herein, the layered structure  16  may include any other cross-sectional shape, such as, but not limited to, a rectangular cross-sectional shape, a square cross-sectional shape, another four-sided cross-sectional shape, an oval cross-sectional shape, a triangular cross-sectional shape, a cross-sectional shape having greater than four sides, and/or the like. 
     Referring now to structure of the layered structure  16  as shown in  FIG. 2 , the base  18  includes an exterior base surface  26  that defines a cross-sectional perimeter of the base  18 . As will be described below, in the illustrated embodiment of  FIGS. 1 and 2 , the interior layer  20  extends on the exterior base surface  26  of the base  18 . The base  18  may have any cross-sectional size (e.g., any diameter in the illustrated embodiment of  FIGS. 1 and 2 ). 
     The base  18  may be fabricated from any materials. In some embodiments, the base  18  includes copper (Cu). For example, the base  18  may be fabricated approximately entirely from copper, or may be only partially fabricated from copper. Examples of embodiments wherein the base  18  is fabricated only partially from copper include, but are not limited to, fabricating the base  18  from a copper alloy, fabricating the base  18  from copper clad steel, fabricating a majority (but less than an approximate entirety) of the base  18  from copper, fabricating equal to or less than approximately 90% of the base  18  from copper, fabricating equal to or less than approximately 95% of the base  18  from copper, and fabricating between approximately 95% and approximately 99% of the base  18  from copper. Examples of copper alloys from which the base  18  may be fabricated include, but are not limited to, brass, phosphor bronze, aluminum (Al) bronze, silicon (Si) bronze, copper nickel (Ni), and/or the like. Examples of other materials that the base  18  may be fabricated from in addition or alternative to copper include, but are not, limited to, tin (Sn), zinc (Zn), aluminum, iron (Fe), silicon, nickel, gold (Au), silver, and/or the like. 
     As shown in  FIG. 2 , the interior layer  20  extends on the exterior base surface  26  of the base  18 . The interior layer  20  includes an exterior surface  28  that defines a cross-sectional perimeter of the interior layer  20 . As will be described below, the intermediate layer  22  extends on the exterior surface  28  of the interior layer  20 . The interior layer  20  may have any cross-sectional thickness T. 
     The interior layer  20  may be fabricated from any materials that enable oxidation to form on the exterior surface  28 . In some embodiments, the interior layer  20  includes copper (Cu). For example, the interior layer  20  may be fabricated approximately entirely from copper, or may be only partially fabricated from copper. Examples of embodiments wherein the interior layer  20  is fabricated only partially from copper include, but are not limited to, fabricating the interior layer  20  from a copper alloy, fabricating the interior layer  20  from copper clad steel, fabricating a majority (but less than an approximate entirety) of the interior layer  20  from copper, fabricating equal to or less than approximately 90% of the interior layer  20  from copper, fabricating equal to or less than approximately 95% of the interior layer  20  from copper, and fabricating between approximately 95% and approximately 99% of the interior layer  20  from copper. Examples of copper alloys from which the interior layer  20  may be fabricated include, but are not limited to, brass, phosphor bronze, aluminum (Al) bronze, silicon (Si) bronze, copper nickel (Ni), and/or the like. Examples of other materials that the interior layer  20  may be fabricated from in addition or alternative to copper include, but are not, limited to, tin (Sn), zinc (Zn), aluminum, iron (Fe), silicon, nickel, gold (Au), and/or the like. 
     In the illustrated embodiment, the interior layer  20  includes nickel. The interior layer  20  will be referred to sometimes below and sometimes otherwise herein as a “nickel layer”  20  and the exterior surface  28  will be referred to sometimes below as an “exterior nickel layer”  28 . In the illustrated embodiment, at least a majority of the nickel layer  20  is fabricated from nickel. In some embodiments, an approximate entirety of the nickel layer  20  is fabricated from nickel. Examples of embodiments wherein a majority, but less than an approximate entirety, of the nickel layer  20  is fabricated from nickel include, but are not limited to, fabricating the nickel layer  20  from a nickel alloy, fabricating equal to or less than approximately 90% of the nickel layer  20  from nickel, fabricating equal to or less than approximately 95% of the nickel layer  20  from nickel, and fabricating between approximately 95% and approximately 99% of the nickel layer  20  from nickel. Examples of nickel alloys from which the nickel layer  20  may be fabricated include, but are not limited to, alnico, alumel, chromel, cupronickel, ferronickel, german silver, hastelloy, inconel, monel metal, nichrome, nickel-carbon, nicrosil, nisil, nitinol, mu-metal, permalloy, supermalloy, and/or the like. 
     In some embodiments, the base  18  and the interior layer  20  of the layered structure are the same layer (i.e., define a single layer of the layered structure). For example, as described above, the base  18  of the layered structure  16  may be fabricated from nickel (e.g., a majority or an approximate entirety of the base  18  may be fabricated from nickel) and/or copper (e.g., a majority or an approximate entirety of the base  18  may be fabricated from copper). In such embodiments wherein a majority or an approximate entirety of the base  18  is fabricated from the same material(s) as the interior layer  20 , the base  18  defines the interior layer  20  such that the exterior base surface  26  is the same surface as the exterior surface  28 . In other words, in some embodiments, the base  18  and the interior layer  20  do not define separate layers of the layered structure  16 , but rather define a single continuous layer of the layered structure  16 . 
     For example,  FIG. 3  is a cross-sectional view of another embodiment of an electrical contact  110 . At least a portion of the electrical contact  110  includes a layered structure  116  having a base  118 , an intermediate layer  122 , and a silver layer  124 . The base  118  defines an interior layer  120  of the layered structure that includes an exterior surface  128 . The intermediate layer  122  extends on the exterior surface  128  of the interior layer  20  and includes an exterior platinum group metal (PGM) surface  130  on which the silver layer  124  extends. The structure and function of the intermediate layer  122  is substantially similar to the intermediate layer  22  ( FIG. 2 ) and therefore will not be described in more detail herein. The structure and function of the intermediate layer  22  will be described in more detail below. 
     Referring again to  FIG. 2 , the intermediate layer  22  extends on the exterior nickel surface  28  of the nickel layer  20 . The intermediate layer  22  includes at least one PGM. The term “PGM” refers to six metallic elements clustered together in the periodic table. PGMs are transition metals lying in the d-block (groups  8 ,  9 , and  10 , periods  5  and  6 ) of the periodic table. The six platinum group metals are ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). PGMs may also be referred to as platinoids, platidises, platinum group, platinum metals, platinum family, or platinum group elements (PGEs). 
     The intermediate layer  22  includes an exterior PGM surface  30  that defines a cross-sectional perimeter of the intermediate layer  22 . As will be described below, the silver layer  24  extends on the exterior PGM surface  30  of the intermediate layer  22 . As shown in  FIG. 2 , the intermediate layer extends a cross-sectional thickness T 1  between the nickel layer  20  and the silver layer  24 . The cross-sectional thickness T 1  of the intermediate layer  22  may have any value. Examples of the cross-sectional thickness T 1  of the intermediate layer  22  include, but are not limited to, less than approximately 500 nanometers (nm), between approximately 2 nm and approximately 501 nm, equal to or less than approximately 50 nm, and greater than or equal to approximately 1 nm. In some embodiments, the cross-sectional thickness T 1  of the intermediate layer  22  is greater than approximately 500 nm. 
     As described above, the intermediate layer  22  includes one or more PGMs. At least a majority of the intermediate layer  22  is fabricated from the one or more PGMs. For example, the intermediate layer  22  may be fabricated approximately entirely from the one or more PGMs. Examples of embodiments wherein a majority, but less than an approximate entirety, of the intermediate layer  22  is fabricated from the one or more PGMs include, but are not limited to, fabricating the intermediate layer  22  from a PGM alloy, fabricating equal to or less than approximately 90% of the intermediate layer  22  from the one or more PGMs, fabricating equal to or less than approximately 95% of the intermediate layer  22  from the one or more PGMs, and fabricating between approximately 95% and approximately 99% of the intermediate layer  22  from the one or more PGMs. In some embodiments, the intermediate layer  22  only includes a single PGM, whether or not the intermediate layer  22  also includes any non-PGM materials. Fabricating the intermediate layer  22  from a single PGM may be easier and/or less costly than fabricating the intermediate layer  22  from two or more PGMs. For example, it may be more difficult and/or costly to deposit (e.g., using a plating process and/or the like) the intermediate layer  22  on the exterior nickel surface  28  of the nickel layer  20  when the intermediate layer  22  includes two or more PGMs as compared to when the intermediate layer  22  includes only a single PGM. Moreover, and for example, it may be more costly to purchase, obtain, generate, and/or the like a substance that includes two or more PGMs as compared to a substance that includes only a single PGM. In one specific example embodiment, at least 95% of the intermediate layer  22  is fabricated from palladium and the intermediate layer does not include any other PGMs. 
     The silver layer  24  extends on the exterior PGM surface  30  of the intermediate layer  22 . As shown in  FIG. 2  and discussed above, the intermediate layer  22  extends between the nickel layer  20  and the silver layer  24 . between the nickel layer  20  and the silver layer  24  within the layered structure  16  of the electrical contact  10 . The silver layer  24  includes an exterior silver surface  32 , which may define a cross-sectional perimeter of the mating segment  12  of the electrical contact  10  depending on whether any other layers extend on exterior silver surface  32  of the silver layer  24 . The silver layer  24  may have any cross-sectional thickness T 2 , which may be selected to provide the electrical contact  10  with a predetermined electrical conductivity. 
     The silver layer  24  includes silver. At least a majority of the silver layer  24  is fabricated from silver. In some embodiments, an approximate entirety of the silver layer  24  is fabricated from silver. Examples of embodiments wherein a majority, but less than an approximate entirety, of the silver layer  24  is fabricated from silver include, but are not limited to, fabricating the silver layer  24  from a silver alloy, fabricating equal to or less than approximately 90% of the silver layer  24  from silver, fabricating equal to or less than approximately 95% of the silver layer  24  from silver, and fabricating between approximately 95% and approximately 99% of the silver layer  24  from silver. Examples of silver alloys from which the silver layer  24  may be fabricated include, but are not limited to, argentium sterling silver, billon, Britannia silver, doré bullion, electrum, goloid, platinum sterling, shibuichi, sterling silver, Tibetan silver, and/or the like. The amount of silver contained within the silver layer  24  may be selected to provide the mating segment  12  of the electrical contact  10  a predetermined electrical conductivity. 
     The PGM(s) of the intermediate layer  22  is miscible in both nickel and silver such that the intermediate layer  22  has at least some mutual solubility with both nickel and silver (e.g., the PGM(s) of the intermediate layer  22  forms a continuous face-centered cubic (FCC) solid solution with both nickel and silver). Accordingly, the crystalline structure of the intermediate layer  22  is bonded with the crystalline structure of the nickel layer  20  at the interface between the layers  20  and  22 , and the crystalline structure of the intermediate layer  22  is bonded with the crystalline structure of the silver layer  24  at the interface between the layers  22  and  24 . The mutual bonding between the layers  20  and  22  and between the layers  22  and  24  provides a relatively strong and relatively stable adhesion between the layers  20  and  22 , between the layers  22  and  24 , and thereby between the nickel layer  20  and the silver layer  24 , for example as compared to direct adhesion between silver and nickel. In some alternative embodiments, the PGM(s) of the intermediate layer  22  are compound forming (e.g., form intermetallics) with nickel such that the intermediate layer  22  forms a compound (e.g., forms intermetallics) with the nickel layer  20  at the interface between the nickel layer  20  and the intermediate layer  22 . 
     The intermediate layer  22  provides a barrier that prevents delamination by preventing an oxide layer from forming between the nickel layer  20  and the silver layer  24 . Specifically, the intermediate layer  22  does not oxidize because the PGM(s) of the intermediate layer  22  does not oxidize. Accordingly, even though oxygen readily diffuses through the silver layer  24 , the intermediate layer  22  provides a barrier that prevents a deleterious oxide layer from forming at the interface between the nickel layer  20  and the intermediate layer  22  (e.g., on the exterior nickel surface  28 ). By preventing an oxide layer from forming on the exterior nickel surface  28 , the barrier provided by the intermediate layer  22  prevents the silver layer  24  from delaminating from the nickel layer  20 . For example, by preventing an oxide layer from forming at the interface between the layer  22  and the layer  20 , the intermediate layer  22  prevents the bonds between the layer  22  and the layers  20  and  24  from being weakened. As used herein, “preventing” oxides and/or an oxide layer from forming is intended to mean preventing the formation of an oxide layer that is sufficient to cause delamination of the silver layer  24 . In other words, “preventing” oxides and/or an oxide layer from forming, as used herein, does not necessarily mean that no oxidation is formed at the interface between the nickel layer  20  and the silver layer  24 . Rather, “preventing” oxides and/or an oxide layer from forming, as used herein, may include the formation of localized discontinuous “lands” of oxide that are not sufficient (e.g., are not continuous with each other) to cause delamination of the silver layer  24 . For example, the intermediate layer  22  may be porous and such localized discontinuous lands of oxide may form at pores of the intermediate layer  22 . In some embodiments, each of the pores of the intermediate layer  22  must be no greater than approximately 0.5 micrometers to prevent the formation of localized discontinuous lands of oxide that are sufficient to cause delamination of the silver layer  24 . Moreover, in some embodiments, the porosity of the intermediate layer  22  must be such that the intermediate layer  22  covers at least approximately 50% of the exterior nickel surface  28  to prevent the formation of localized discontinuous lands of oxide that are sufficient to cause delamination of the silver layer  24 . 
     The intermediate layer  22  is configured to prevent the silver layer  24  from delaminating from the nickel layer  20  at temperatures greater than 150° C. Specifically, the intermediate layer  22  prevents oxides from forming at the interface between the layer  22  and the layer  20  and the intermediate layer  22  bonds with the layers  20  and  24  such that the bonds between the intermediate layer  22  and the layers  20  and  24  may remain sufficiently strong at temperatures greater than 150° C. to prevent the silver layer  24  from delaminating from the nickel layer  20 . 
     Moreover, because the intermediate layer  22  prevents oxides from forming, it is not necessary to use a layer that forms intermetallics at the interface between the nickel layer  20  and the intermediate layer  22  nor at the interface between the intermediate layer  22  and the silver layer  24 . For example, it is known to include an intermetallic forming layer to thereby form intermetallics at the interfaces between the nickel and silver layers to provide sufficiently strong adhesion between the nickel and silver layers and thereby mitigate weakening of the adhesion caused by the formation of oxide layers. But, forming intermetallics may be difficult and/or costly. For example, it may be necessary to heat treat the electrical contact to sufficiently form the intermetallics between the strike layer and the nickel and silver layers. Such heat treatment adds a manufacturing step that may be relatively time consuming and/or costly. Accordingly, the PGM(s) of the intermediate layer  22  may reduce the cost, difficulty, and/or time of manufacturing the electrical contact, for example as compared to at least some known electrical contacts that include nickel and silver layers. 
     Moreover, because the intermediate layer  22  prevents oxidation, the intermediate layer  22  may be thinner than the strike layer of at least some known electrical contacts that include nickel and silver layers. For example, at least some known strike layers may not prevent oxidation therefore may be required to have a sufficient thickness that provides enough intermetallic formation with sufficiently strong adhesion to sufficiently mitigate weakening of the adhesion between the nickel and silver layers caused by the formation of any oxide layers. By preventing oxide layers from forming at the interfaces between the layer  22  and the layers  20  and  24 , the intermediate layer  22  prevents the bonds between the layer  22  and the layers  20  and  24  from being weakened by such oxide layers. The thickness T 1  of the intermediate layer  22  may therefore be reduced as compared to the strike layer of at least some known electrical contacts that include nickel and silver layers. The thickness T 1  of the intermediate layer  22  may selected to provide the bonds between the layer  22  and the layers  20  and  24  with a sufficient strength to prevent the silver layer  24  from delaminating from the nickel layer  20  at a predetermined temperature that is greater than 150° C. 
       FIG. 4  is a flowchart illustrating a method  200  for fabricating an electrical contact, for example the electrical contact  10  ( FIGS. 1 and 2 ) or the electrical contact  110  ( FIG. 3 ). At  402 , the method  400  includes depositing an intermediate layer (e.g., the intermediate layer  22  shown in  FIG. 2  or the intermediate layer  122  shown in  FIG. 3 ) on an exterior surface (e.g., the exterior nickel surface  28  shown in  FIG. 2  or the exterior surface  128  shown in  FIG. 3 ) of an interior layer (e.g., the nickel layer  20  shown in  FIG. 2  or the nickel layer  120  shown in  FIG. 3 ) of the electrical contact. Depositing at  402  the intermediate layer on the exterior surface of the interior layer may include bonding, at  402   a , a crystalline structure of the intermediate layer with a crystalline structure of the interior layer. 
     The intermediate layer may be deposited at  402  on the exterior surface of the interior layer using any process, such as, but not limited to, a plating process, a spraying process, a sputtering process, a chemical vapor deposition (CVD) process, and/or the like. Any type of plating process may be used to deposit the intermediate layer on the exterior surface of the interior layer, such as, but not limited to, electroplating, electroless plating, and/or the like. Accordingly, depositing at  402  the intermediate layer on the exterior surface of the interior layer optionally includes depositing at  402   b  the intermediate layer on the exterior surface of the interior layer using a plating process. 
     At  404 , the method  400  includes depositing a silver layer (e.g., the silver layer  24  shown in  FIG. 2  or the silver layer  124  shown in  FIG. 3 ) on an exterior PGM surface (e.g., the exterior PGM surface  30  shown in  FIG. 2  or the exterior PGM surface  130  shown in  FIG. 3 ) of the intermediate layer such that the intermediate layer extends between the interior layer and the silver layer. Depositing at  404  the silver layer on the exterior PGM surface of the intermediate layer may include bonding, at  404   a , a crystalline structure of the silver layer with the crystalline structure of the intermediate layer. 
     The silver layer may be deposited at  404  on the exterior PGM surface of the intermediate layer using any process, such as, but not limited to, a plating process, a spraying process, a sputtering process, a chemical vapor deposition (CVD) process, and/or the like. Any type of plating process may be used to deposit the silver layer on the exterior PGM surface of the intermediate layer, such as, but not limited to, electroplating, electroless plating, and/or the like. Accordingly, depositing at  404  the silver layer on the exterior PGM surface of the intermediate layer optionally includes depositing at  404   b  the silver layer on the exterior PGM surface of the intermediate layer using a plating process. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.