Patent Application
20140308540
The present invention is directed to plated contacts and processes of manufacturing plated contacts. More particularly, the present invention is directed to plated contacts having two or more tin-containing seal platings.
Electrical conductors are utilized in various applications from transmitting data signals to providing a connection across which electrical current may flow. Contacts between two transmitters of electrical current or data signals allow the electrical current or data signals to be transmitted from one conductor to another.
Prior art connectors have included nickel-gold-plated copper conductors. However, pitting corrosion has occurred in such constructions that have resulted in the deterioration of the contacts, which in turn has adversely affected electrical performance. While nickel-based layers (for example, including nickel or nickel alloys, such as, NiP, NiW, and NiPd) have been used as a buffer layer between the outer gold-plating layer and the copper substrate, pitting corrosion occurs through the nickel-gold layer due to pin holes extending through the gold-plating layer and nickel-based layer. Such pin-holes are especially prevalent when using certain application technologies on thin layers, for example, physical vapor deposition.
One solution to the pitting problem has been to apply a seal-plating layer between the nickel layer and the copper layer. The seal-plating layer preferably has been tin-containing (Sn) applied over the copper substrate and in contact with the nickel (Ni) plating layer. After application, the Sn forms an intermetallic with Cu as well as with Ni at its interface with each of these materials. The intermetallic layers are formed either as a result of solid state interdiffusion, which may occur either at room temperature or as a result of an elevated temperature heat treatment, or as a result of Sn reflow. Intermetallic materials are very corrosion resistant, but are also significantly harder and less ductile than the copper substrate over which the Sn is applied, or the Ni or nickel alloys applied over the Sn. The thickness of the intermetallic materials formed by heat treatment or Sn reflow creates an intermetallic layer that is also brittle. Thus, while this solution has solved the problem of pitting, delamination occurs at the thick and brittle intermetallic layer between Ni and Sn, and from the readily formed thin Sn oxide layer from the exposure of Sn to the atmosphere between the Sn and Ni plating operations.
A solution to both the delamination problem and to the pitting problem created by the use of Au/Ni applied over copper substrates or Au/Ni/Sn applied over copper substrates has been achieved by using vapor phase reflow. However, the solution can result in coalescing of pores within the Sn, which can be detrimental to corrosion resistance.
A plated contact and a process of manufacturing a plated contact that do not suffer from one or more of the above drawbacks would be desirable in the art.
In an exemplary embodiment, a process for manufacturing a plated contact includes providing a metallic substrate, applying a first tin-containing plating over the metallic substrate, applying a first corrosion-prevention plating over the first tin-containing plating, applying a second tin-containing plating over the first corrosion-prevention plating, applying a second corrosion-prevention plating over the second tin-containing plating, and applying a gold plating over the second corrosion-prevention plating to form the plated contact. One or both of the first corrosion-prevention plating and the second corrosion-prevention plating includes nickel, a nickel-based alloy, copper, a copper containing alloy, or a combination thereof
In another exemplary embodiment, a process for manufacturing a plated contact includes providing a metallic substrate, applying a first tin-containing plating of about 0.38 micrometers (15×10−6 inches) to the metallic substrate, rinsing and drying the first tin-containing plating, applying a first corrosion-prevention plating of about 0.5 micrometers (20×10−6 inches) over the first tin-containing plating, rinsing and drying the first corrosion-prevention plating, applying a second tin-containing plating of about 0.38 micrometers (15×10−6 inches) to the first corrosion-prevention plating, rinsing and drying the second tin-containing plating, applying a second corrosion-prevention plating of about 0.76 micrometers (30×10−6 inches) over the second tin-containing plating, rinsing and drying the second corrosion-prevention plating, applying a gold plating over the second corrosion-prevention plating to form the plated contact, and rinsing and drying the plated contact. One or both of the first corrosion-prevention plating and the second corrosion-prevention plating includes nickel, a nickel-based alloy, copper, a copper containing alloy, or a combination thereof.
In another exemplary embodiment, a plated contact includes a metallic substrate, a first tin-containing plating over the metallic substrate, a first corrosion-prevention plating over the first tin-containing plating, a second tin-containing plating over the first corrosion-prevention plating, a second corrosion-prevention plating over the second tin-containing plating, and a gold plating over the second corrosion-prevention plating to form the plated contact. One or both of the first corrosion-prevention plating and the second corrosion-prevention plating includes nickel, a nickel-based alloy, copper, a copper containing alloy, or a combination thereof.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.
Provided is an exemplary plated contact and a process of manufacturing a plated contact. Embodiments of the present disclosure, for example, in comparison to plated contacts and processes of manufacturing plated contacts that do not include one or more of the features disclosed herein, reduce or eliminate corrosion, reduce or eliminate delamination, reduce or eliminate coalescing of pores within one or more tin-containing seals, permit soldering of nickel to copper since tin-containing is used as a solder to join nickel and copper, convert at least a portion of tin-containing present into tin-containing intermetallics, permit more coating application technologies to be used to apply thinner layers (for example, physical vapor deposition), disrupt formation and/or alignment of through-holes in Au/Ni/Sn layer arrangements, or a combination thereof.
The process 100 includes providing the metallic substrate 203 (step 102), applying the first tin-containing plating 205 over the metallic substrate 203 (step 104), applying the first corrosion-prevention plating 207 over the first tin-containing plating 205 (step 106), applying a second tin-containing plating 209 over the first corrosion-prevention plating 207 (step 108), applying the second corrosion-prevention plating 211 over the second tin-containing plating 209 (step 110) and applying the gold plating 213 over the second corrosion-prevention plating 211 to form the plated contact 201 (step 112). In one embodiment, these platings and/or other platings applied according to the disclosure are rinsed and/or dried as part of the process 100, for example, with or without activation of the tin-containing plating 205.
In further embodiments, additional layers are applied to the plated contact 201. For example, in one embodiment, the plated contact 201 further includes a third tin-containing plating (not shown) over the second corrosion-prevention plating 211, and a third corrosion-prevention plating (not shown) over the third tin-containing plating. In yet a further embodiment, a fourth tin-containing plating (not shown) is over the third corrosion-prevention plating and a fourth corrosion-prevention plating (not shown) is over the fourth tin-containing plating. As will be appreciated, any suitable number of the corrosion-prevention platings and the tin-containing platings are capable of being included to provide a desired amount of corrosion resistance, resistance to delamination, and/or other properties.
The platings include any suitable thicknesses capable of providing desired properties, for example, desirably balancing Ni with Sn or Cu to convert all Ni to intermetallics and/or being at a reduced thickness to decrease costs. The first tin-containing plating 205 has a first thickness and the second tin-containing plating 209 has a second thickness, the first thickness differing from the second thickness or the first thickness being equal to the second thickness. Suitable ranges of thicknesses for the first tin-containing plating 205 and/or the second tin-containing plating 209 include, but are not limited to, between about 0.25 micrometers (10×10−6 inches) and about 1 micrometer (40×10−6 inches), between about 0.38 micrometers (15×10−6 inches) and about 1 micrometer (40×10−6 inches), between about 0.25 micrometers (10×10−6 inches) and about 0.76 micrometers (30×10−6 inches), between about 0.38 micrometers (15×10−6 inches) and about 0.76 micrometers (30×10−6 inches), or any suitable combination, sub-combination, range, or sub-range therein.
The first corrosion-prevention plating 207 has a first thickness and the second corrosion-prevention plating 211 has a second thickness, the first thickness differing from the second thickness or being equal to the second thickness. Suitable ranges of thicknesses for the first corrosion-prevention plating 207 and/or the second corrosion-prevention plating 211 include, but are not limited to, between about 0.25 micrometers (10×10−6 inches) and about 1.52 micrometers (60×10−6 inches), between about 0.5 micrometers (20×10−6 inches) and about 1.52 micrometers (60×10−6 inches), between about 0.5 micrometers (20×10−6 inches) and about 1.27 micrometers (50×10−6 inches), between about 0.5 micrometers (20×10−6 inches) and about 0.76 micrometers (30×10−6 inches), between about 0.76 micrometers (30×10−6 inches) and about 1.52 micrometers (60×10−6 inches), between about 0.76 micrometers (30×10−6 inches) and about 1.27 micrometers (50×10−6 inches), between about 1.27 micrometers (50×10−6 inches) and about 1.52 micrometers (60×10−6 inches), or any suitable combination, sub-combination, range, or sub-range therein.
In one embodiment, the gold plating 213 has a thickness, for example, between about 0.025 micrometers (1×10−6 inches) and about 1.27 micrometers (50×10−6 inches), between about 0.025 micrometers (1×10−6 inches) and about 0.76 micrometers (30×10−6 inches), between about 0.025 micrometers (1×10−6 inches) and about 0.38 micrometers (15×10−6 inches), between about 0.025 micrometers (1×10−6 inches) and about 0.25 micrometers (10×10−6 inches), between about 0.025 micrometers (1×10−6 inches) and about 0.13 micrometers (5×10−6 inches), between about 0.13 micrometers (5×10−6 inches) and about 0.38 micrometers (15×10−6 inches), between about 0.13 micrometers (5×10−6 inches) and about 0.25 micrometers (10×10−6 inches), between about 0.25 micrometers (10×10−6 inches) and about 0.38 micrometers (15×10−6 inches), about 0.76 micrometers (30×10−6 inches), about 1.27 micrometers (50×10−6 inches), greater than about 1.27 micrometers (50×10−6 inches), or any suitable combination, sub-combination, range, or sub-range therein.
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The vapor phase reflow (step 114) involves heating a component above its melting temperature using a fluid having a known vaporization temperature above the melting temperature of the component. In one embodiment, the process 100 includes the vapor phase reflow (step 114), for example, heating Sn above its melting temperature. The vaporization of the fluid is at a substantially uniform temperature that is very difficult to exceed. The vapor phase reflow operation itself involves vaporization of a fluid. The vapor phase is inert and is capable of being done oxygen-free, when the enclosure containing the vapor phase is properly designed to contain the vapor while sealing out oxygen. The oxygen is capable of being removed by introduction of a non-oxidizing gas to displace the oxygen or by pulling vacuum prior to introduction of the vapor phase. This also delivers a consistent heating across the plated contact 201, while limiting absolute maximum temperature. Any suitable vapor phase reflow fluid is utilized, for example, perfluorinated fluids that are non-corrosive, are non-flammable, are non-toxic, and/or leave no residue after evaporation. Suitable perfluorinated fluids include, but are not limited to, HS/240 and HS/260 perfluoropolyether (PFPE) fluids (available from Solvay Solexis, Anaheim, Calif.), with 240 and 260 referring to the targeted reflow temperatures of each respective fluid: 240° C. (464° F.) and 260° C. (500° F.).
The vapor phase reflow (step 114) transfers heat faster than other heating processes, such as infrared and convection oven heating, even in controlled atmospheres. As a result, the plated contact 201 is capable of being heated to a uniform temperature for a short period of time, while obtaining uniform heating across the contact.
The process 100 is capable of being adapted to continuous processing. For example, in one embodiment, the metallic substrate 203 is provided on reels (not shown) and the reels are processed continuously through various baths (not shown) prior to being sent through the vapor phase reflow (step 114). After the vapor phase reflow (step 114), the plated contacts 201 are then processed onto a reel for further processing.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
