EP4587621A1 - A coated tungsten and/or molybdenum object and manufacturing method thereof - Google Patents

Abstract

A metal object (100), the object comprising a core (110) comprising tungsten and / or molybdenum. The object (100) further comprises an adhesion layer (120), which comprises any of palladium, platinum, silver, copper, and rhodium, or alloys thereof, wherein the adhesion layer (120) has a thickness (t) equal to or less than 200 nm.

Description

TITLE

A coated tungsten and/or molybdenum object and manufacturing method thereof

TECHNICAL FIELD

The present disclosure relates to a metal object coated in a layer of another metal, particularly to a coated metal wire comprising tungsten and/or molybdenum.

BACKGROUND

Coatings are applied to metal objects for a variety of reasons, including in order to alter the surface properties of the object and to protect the underlying material from corrosion.

Tungsten and molybdenum components, such as wires, are used in antennas, mesh reflectors, fuses, and for lighting, among other applications. Coating tungsten and molybdenum components, e.g. by plating, with a noble metal such as gold increases the corrosion resistance of the materials and can provide improved wettability for soldering.

One of the most important current and future application areas for gold plated tungsten and I or molybdenum wires are reflectors that form part of self-deployable satellite antennas. The wires are knitted into meshes which constitute part of the reflector. The gold improves the reflectivity of the reflector, contributing to a better reflection of the signals. Such antennas can be used at high frequencies, which is important for advanced applications such as Earth Observation or communications in near-Earth orbit.

However, most other metals do not adhere strongly to either tungsten or molybdenum, necessitating the use of an adhesion layer.

JP2524432 B2 discloses plating of a tungsten wire with an adhesion layer comprising gold or nickel.

JP2999041 B2 discloses plating of a tungsten wire with gold, copper, and nickel in order to improve adhesion of other metals.

Use of nickel as an adhesion layer is undesirable in many applications, particularly due to problems with sustainability and the toxicity of nickel. Thus, there is a need for improved adhesion layers for tungsten and molybdenum objects.

SUMMARY

It is a goal of the present disclosure to provide improved metal-plated tungsten and molybdenum objects. This goal is at least in part obtained by a metal object comprising a core which comprises tungsten and I or molybdenum. The object further comprises an adhesion layer. The adhesion layer comprises any of palladium, platinum, silver, copper, and rhodium. The adhesion layer may also comprise alloys that comprise any of palladium, platinum, silver, copper, and rhodium. The adhesion layer has a thickness equal to or less than 200 nm.

A thin layer of palladium or a palladium alloy used as an adhesion layer adheres well to tungsten and molybdenum and provides improved adhesion also for additional layers of other metals deposited on top. An adhesion layer comprising palladium, platinum, silver, copper, and I or rhodium as described above can be used instead of an adhesion layer comprising nickel, which is an advantage due to the toxicity and negative environmental effects of nickel. An adhesion layer as described above can also be used instead of an adhesion layer comprising gold. Gold adhesion layers are sometimes used in place of nickel, but do not produce the same improvement in adhesion. An adhesion layer as described above is thus an improvement over both nickel and gold.

The thickness of the adhesion layer can be adapted to the type of object, the application, and the materials used. According to some aspects, the thickness of the adhesion layer is 10 to 20 nm, 40 to 60 nm, or 100 to 150 nm.

The plated metal object may be a wire. Wires comprising tungsten and/or molybdenum are frequently used in devices such as antennas, reflectors, fuses and other electrical components, and for lighting. Plating such wires with another metal makes it possible to enhance surface properties such as solderability, corrosion resistance, and reflectivity, which is an advantage.

According to one alternative, the wire has a circular cross-section. According to another alternative, the wire has a rectangular or square cross-section.

Advantageously, the wire can be given the cross-sectional shape most suitable for its intended use. According to aspects, a metal comprised in the adhesion layer and a metal comprised in the core can form an alloy in a region adjacent to the surface of the core. This can especially occur if the core comprises tungsten. The formation of an alloy region leads to improved adhesion of the adhesion layer to the core, which in turn can improve the adhesion of any outer layer deposited on top of the adhesion layer.

According to some aspects, the plated metal object comprises an outer layer arranged on an outer surface of the adhesion layer. The outer layer comprises a metal or metal alloy. The metals comprised in the outer layer and the thickness of the outer layer can be selected depending on what surface properties the object should have in a specific application. That is, the outer layer can be selected to improve properties such as reflectivity, solderability, and I or corrosion resistance. Due to the presence of the adhesion layer, it is possible to use metals that would normally not adhere to a tungsten or molybdenum surface, which is an advantage. The outer layer may for example comprise any of Cu, Sn, Au, Ag, Zn, Pd, Pt, and Rh. The outer layer may also comprise alloys that comprise any of Cu, Sn, Au, Ag, Zn, Pd, Pt, and Rh.

The goal is also at least partly obtained by a method for producing a plated metal object as described above. The object comprises a core, where the core comprises any of tungsten and molybdenum. The method comprises activating the surface of the core, rinsing the surface of the core, and plating the core with any of palladium, platinum, silver, copper, and rhodium, and/or alloys of these metals, to form the adhesion layer. The adhesion layer has a thickness equal to or less than 200 nm. The method further comprises rinsing the surface of the adhesion layer and performing a heat treatment of the object.

Advantageously, this method produces a thin adhesion layer that adheres strongly to the surface of the core.

According to one alternative, activating the surface of the core comprises performing an electrolytical etching procedure on the surface of the core. This activation process prepares the surface of the core for plating, e.g. by removing oxides and contaminants that have formed on the surface.

According to some aspects, performing a heat treatment of the object comprises heating the object to a temperature above 400 °C in the presence of a gas. The gas may be an inert gas. The heat treatment assists in creating a bond between the core and the adhesion layer and can also facilitate interdiffusion of the metals comprised in the adhesion layer and the metals comprised in the core. This is particularly the case for objects comprising tungsten.

Heating the object in a controlled atmosphere containing an inert gas has the advantage of not introducing unwanted reagents such as oxygen gas during the high- temperature treatment.

The method may also comprise performing a heat treatment of the core prior to plating the core to form the adhesion layer. This has the advantage of further preparing the surface of the core for plating.

The method may further comprise plating the object to form an outer layer on top of the adhesion layer. The outer layer can comprise a metal or metal alloy. Accordingly, plating the object to form an outer layer may comprise plating the object with any of Au, Sn, Cu, Ag, Zn, Pd, Pt, and Rh, and/or with alloys of these metals.

The outer layer can be selected to give the object desired surface properties, such as increased solderability, reflectivity, and I or corrosion resistance. Due to the presence of the adhesion layer, metals which would normally not adhere sufficiently to tungsten or molybdenum can be used, which is an advantage.

Generally, the methods disclosed herein are associated with the same advantages as discussed above in connection to the different devices.

Finally, there is herein disclosed a machine arranged to produce a metal object as described above.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described in more detail with reference to the appended drawings, where:

Figure 1 schematically illustrates a cross-section of a plated metal object;

Figure 2A, B schematically illustrate cross-sections of plated metal wires;

Figure 3 schematically illustrates a plated metal object;

Figure 4 is a flow chart illustrating methods; and

Figure 5 schematically illustrates a machine for producing a plated metal object.

It should be noted that the drawings are schematic and not to scale.

DETAILED DESCRIPTION

Aspects of the present disclosure will now be described more fully with reference to the accompanying drawings. The different devices and methods disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.

The terminology used herein is for describing aspects of the disclosure only and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Tungsten and molybdenum are frequently used in specialized applications, such as in antennas, mesh reflectors, fuses and other electrical components, and for lighting. Tungsten and molybdenum wires can also be used in biomedical applications, e.g. to increase the detectability of stents by X-ray imaging. This is due to tungsten and molybdenum having advantageous properties such as high density, high melting points, and low thermal expansion compared to other metals. Tungsten and molybdenum also have relatively high strength, a low degree of softening and deformation at high temperature and are relatively resistant to wear.

However, both tungsten and molybdenum can be difficult to solder due to their surface properties. Additionally, although both molybdenum and tungsten are resistant to corrosion, they are not as corrosion resistant as noble metals such as gold. In some applications, it is also desirable to alter properties such as the reflectivity of the metals. This is for example the case for reflectors that form part of self-deployable satellite antennas.

To improve the surface properties of tungsten and molybdenum components, it is necessary to coat the surface with a different material through processes such as electroplating. However, many other metals do not adhere strongly to either tungsten or molybdenum, necessitating the use of an adhesion layer.

Figure 1 shows a cross-section of a metal object 100. The object comprises a core 110 which in turn comprises tungsten and I or molybdenum. The object 100 further comprises an adhesion layer 120, which comprises any of palladium, platinum, silver, copper, and rhodium. The adhesion layer may also comprise alloys of these metals. The adhesion layer 120 has a thickness t equal to or less than 200 nm.

That the object comprises tungsten and I or molybdenum should not be taken to mean that it can only comprise pure tungsten or molybdenum. In most cases, the tungsten or molybdenum metal forms part of an alloy. As an example, the object may comprise an alloy of tungsten and potassium, as alloying tungsten with potassium is known to improve strength and ductility. The alloy may comprise mainly tungsten with a small amount of potassium added, also referred to as potassium-doped tungsten. The amount of potassium can for example be up to 100 parts per million (ppm). The amount of potassium could also be 60-65 ppm.

As another example, the object may comprise an alloy of molybdenum with lanthanum and I or lanthanum oxide. The alloy could e.g. comprise molybdenum with up to 0.7 % lanthanum oxide added. The alloy could also comprise molybdenum and 200-400 ppm lanthanum.

Likewise, as mentioned above, the adhesion layer 120 might not comprise pure palladium, platinum, silver, copper, or rhodium, but may instead comprise an alloy comprising one or more of these metals. Such an alloy may also comprise metals other than palladium, platinum, silver, copper, or rhodium. It is also possible that the adhesion layer 120 comprises a small amount of impurities of other materials. A small amount could for example be less than 500 ppm, or less than 50 ppm.

The thickness of the adhesion layer can be selected in dependence of the intended use of the object, whether the object comprises tungsten or molybdenum, and the metal chosen for the adhesion layer. When the adhesion layer is formed through plating, the thickness of the adhesion layer can be determined by altering processing parameters such as the temperature of the plating solution, the concentration of metal salts in the plating solution, processing speed, and current, among others. The manufacturing process will be discussed further below.

According to some examples, the thickness t of the adhesion layer 120 is 10 to 20 nm or 40 to 60 nm. According to other examples, the adhesion layer may have a thickness t of 100 to 150 nm. The adhesion layer could also have a thickness of around 25, 30, or 50 nm.

The metal object 100 can be any type of object that has a core comprising tungsten and I or molybdenum and an adhesion layer as described above. As an example, the object 100 can be an electrical component, an antenna, or a reflector.

The object 100 may also be a wire 200, or an object formed from one or more wires comprising tungsten and I or molybdenum. For example, the object 100 can be a reflector or a component of a reflector formed from wires that are knitted into a mesh.

In the case where the object is a wire, the wire can have a variety of cross-sectional shapes and sizes. According to one alternative, the wire 200 has a circular crosssection as shown schematically in Figure 2A. The diameter of the wire can according to one example be between 5 and 300 pm. According to another example, the diameter may be up to 1 mm. The diameter can also be around 20 pm, particularly for molybdenum wires, or around 60 pm, especially for tungsten wires.

According to another alternative, the wire 200 has a rectangular or square crosssection as shown schematically in Figure 2B. For a wire with a substantially square cross-section, the width a and height b may be in the interval 5 to 300 pm. For a wire with a substantially rectangular cross-section, the width a may be larger than the height b as shown in Figure 2B, or vice versa.

It should be noted that when referring to a wire with a circular, square, or rectangular cross-section, it should be taken to mean that the wire is substantially circular, square, or rectangular within the tolerance of the method used for wire production.

In particular, for wires with square or rectangular cross-section, the corners are not expected to form an exact 90-degree angle or be arbitrarily sharp. Instead, the corners form a right angle within the tolerances of the fabrication method. The corners may also be rounded.

Furthermore, the wire 200 may have a cross-section that is other than substantially circular, square, or rectangular. The cross-section may for instance be elliptical or hexagonal, or may be uneven in shape. The size of such wires is generally similar to the size of wires with circular, square, or rectangular cross-sections. As an example, for a wire with an elliptical cross-section the major axis may be between 5 to 300 pm or up to 1 mm, similarly to the diameter of a wire with a circular cross-section. For wires with a hexagonal or uneven cross-section, the size could be measured as the largest distance between two points on the circumference of the cross-section. This size could then be between 5 and 300 pm or up to 1 mm.

It should also be noted that the boundary between the core 110 and the adhesion layer 120 is not necessarily a sharp boundary, but that there may be some interdiffusion between the material of the core 110 and the material of the adhesion layer 120. Thus, a metal comprised in the adhesion layer 120 and a metal comprised in the core 110 can form an alloy in a region 121 adjacent to the surface of the core 110 as shown schematically in Figure 3. In particular, when the core 110 comprises tungsten a substantial fraction of the metal or metals deposited to form the adhesion layer 120 may diffuse into the core 110 and form the alloy region 121. The fraction of deposited metal that enters into the core 110 depends on e.g. the composition of the core and the amount of metal deposited when forming the adhesion layer 120. It can also be affected by processing steps performed during manufacturing, such as the temperature selected for heat treatment. According to some examples, the fraction of the deposited metal that enters into the core 110 may be up to 50 %. The fraction of the deposited metal that enters into the core 110 may also be any of 10 %, 25 % and 40 %.

The formation of an alloy in the region 121 also affects the final thickness of the adhesive layer 120, such that if a large fraction of the deposited metal enters into the core to form the region 121, the adhesive layer 120 will be thinner.

The adhesive layer 120 is intended to improve the adherence of other coatings to the metal object 110. Thus, the object 100 may also comprise an outer layer 130 arranged on an outer surface of the adhesion layer 120. This is shown schematically in Figures 1, 2A, and 2B. The outer layer 130 comprises a metal or metal alloy. The outer layer is intended give the object 100 desired surface properties, such as solderability, improved corrosion resistance, and/or improved reflectivity. The thickness of the outer layer can be selected in dependence of the desired surface properties of the finished object 100. The metal or metals comprised in the outer layer 130 can also be selected based on what surface properties are needed, e.g. a noble metal such as gold or platinum may be selected for improved corrosion resistance. The outer layer 130 can for example comprise any of Cu, Sn, Au, Ag, Zn, Pd, Pt, and Rh, or alloys comprising these metals.

In particular, there is herein disclosed:

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and/or its alloys, and an outer layer 130 comprising copper and/or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising rhodium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising silver and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising zinc and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising platinum and I or its alloys. An object with a core 110 comprising tungsten, and adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising palladium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer comprising copper and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer comprising rhodium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer comprising silver and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer comprising zinc and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and I or its alloys, and an outer layer comprising platinum and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising palladium and/or its alloys, and an outer layer 130 comprising palladium and/or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising copper and I or its alloys. An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising rhodium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising silver and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising zinc and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising palladium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising platinum and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising copper and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer 130 comprising tin and I or its alloys. An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising rhodium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising silver and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising zinc and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising palladium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising platinum and I or its alloys, and an outer layer comprising platinum and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising copper and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising rhodium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising silver and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and / or its alloys, and an outer layer 130 comprising zinc and / or its alloys. An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising palladium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising platinum and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising copper and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising rhodium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising silver and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising zinc and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising palladium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising silver and I or its alloys, and an outer layer comprising platinum and I or its alloys. An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising copper and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising rhodium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising silver and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising zinc and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising palladium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising platinum and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising copper and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer 130 comprising tin and I or its alloys. An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising rhodium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising silver and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising zinc and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising palladium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising copper and I or its alloys, and an outer layer comprising platinum and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising copper and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising rhodium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising silver and I or its alloys. An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising zinc and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising palladium and I or its alloys.

An object with a core 110 comprising tungsten, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising platinum and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising copper and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising gold and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer 130 comprising tin and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising rhodium and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising silver and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising zinc and I or its alloys.

An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising palladium and I or its alloys. An object with a core 110 comprising molybdenum, an adhesion layer 120 comprising rhodium and I or its alloys, and an outer layer comprising platinum and I or its alloys.

There is also herein disclosed a method, illustrated in Figure 4, for producing a plated metal object 100 as described above. The object 100 comprises a core 110 which in turn comprises any of tungsten and molybdenum. The method comprises activating S1 the surface of the core 110, rinsing S2 the surface of the core 110, and plating S4 the core 110 with any of palladium, platinum, silver, copper, and rhodium, or with alloys of these metals, to form an adhesion layer 120. The adhesion layer 120 has a thickness t equal to or less than 200 nm. The method also comprises rinsing S5 the surface of the adhesion layer 120 and performing S6 a heat treatment the object 100.

Rinsing S2, S5 the surface of the core and the surface of the adhesion layer may for example be performed using deionized water.

Activating S1 the surface of the core 110 may comprise performing an electrolytical etching procedure on the surface of the core 110.

Electrolytical etching methods entail the use of an electrolyte and one or more electrodes to etch a surface and are known in the art. The composition of the electrolyte and the material of the electrodes used can here be chosen depending on the materials comprised in the core and on a desired result, such as a desired etching depth. According to some aspects, graphite electrodes or another inert electrode may be used.

The method may also comprise performing S3 a heat treatment of the core 110 prior to plating S4 the core to form the adhesion layer 120. That is, after activation S1 and rinsing S2, the core 110 can be exposed to elevated temperatures. The elevated temperatures may for example be over 400 °C. The temperature of the furnace may also be adjusted depending on the material of the core, e.g. a core comprising tungsten may require a higher temperature than one comprising molybdenum. The heat treatment S3 may take place in an inert atmosphere.

The plating S4 takes place in a plating solution comprising the metal or metals selected for the adhesion layer in the form of ions, along with a counterion of the opposite charge.

The duration of the plating step, the concentration of the metal in the plating solution, the temperature, and the current can be adjusted in order to achieve a desirable result and a required thickness of the adhesion layer. An example setup may use a plating solution with a concentration 1 g/l or more of the metal to be plated, for example palladium, at a temperature in the interval of 20 °C to 70 °C. The processing parameters may need to be adjusted depending on whether the core comprises tungsten or molybdenum as well as depending on which metal or metals are selected for the adhesion layer.

Performing S6 a heat treatment of the object 100 after the plating step may comprise heating the object 100 to a temperature above 400 °C in the presence of a gas. According to aspects, the gas can be an inert gas. An inert gas can for example be nitrogen or a noble gas. The gas can be selected depending on the metal or metals used in the adhesion layer.

The temperature of the furnace can also be adjusted depending on the metals present in the core 110 and the metals present in the adhesion layer 120, with the aim of achieving a high degree of adherence between the core 110 and the adhesion layer 120.

According to one alternative, the method comprises plating S7 the object 100 to form an outer layer 130 on top of the adhesion layer 120. Plating S7 the object 100 to form an outer layer 130 may comprise plating the object 100 with any of Au, Sn, Cu, Ag, Zn, Pd, Pt, and Rh, or alloys thereof.

Plating the object to form an outer layer can be performed according to conventional methods for electroplating.

There is furthermore herein disclosed a machine arranged to perform the abovementioned method to produce a plated metal object. Figure 5 schematically illustrates a machine 500 arranged to produce a plated metal object 100 as described above. The machinery comprises an activation receptacle 510 that can for example be a setup for electrolytical etching. The machinery further comprises a first and second rinsing apparatus 520, 550, arranged to rinse the object 100 e.g. with deionized water.

The machinery also comprises an electroplating setup 540 for plating S4 the core 110 of the object with any of palladium, platinum, silver, copper, and rhodium, or alloys thereof, to form the adhesion layer 120. The machinery further comprises a heat treatment setup 560 arranged to perform S6 a heat treatment of the object. According to some alternatives, the machinery may comprise a second electroplating setup 570 configured for plating S7 the object 100 with an outer layer 130 on top of the adhesion layer 120. The machinery may also comprise a second heat treatment apparatus 530 arranged to heat S3 the object 100 between the first rinsing step and the first electroplating step. If the object 100 is a wire, it is advantageous to perform the method as a reel-to-reel process. This can be done by placing the wire on a spool at one end of the machinery 500, e.g. at the activation receptacle 510, and let it run through the machinery to a second spool at the other end, which may be after the heat treatment setup 560 or optionally after the second electroplating setup 570. The wire can then be pulled through the machinery at a rate suitable for achieving the desired result in each activation step. Preferably, the wire passes through at least the activation receptacle 510, the rinsing apparatus 520, the first electroplating setup 540, the second rinsing apparatus 550, and the heat treatment setup 560 during the reel-to-reel process.

Claims

1. A metal object (100), the object comprising a core (110) comprising tungsten and I or molybdenum, the object (100) further comprising an adhesion layer (120), the adhesion layer (120) comprising any of palladium, platinum, silver, copper, and rhodium, or alloys thereof, wherein the adhesion layer (120) has a thickness (t) equal to or less than 200 nm.

2. The object (100) according to claim 1 , wherein the thickness (t) of the adhesion layer (120) is 10 to 20 nm, 40 to 60 nm, or 100 to 150 nm.

3. The object (100) according to claim 1 or 2, where the object (100) is a wire (200).

4. The object (100) according to claim 3, where the wire (200) has a circular crosssection.

5. The object (100) according to claim 3, wherein the wire (200) has a rectangular or square cross-section.

6. The object (100) according to any previous claim, wherein a metal comprised in the adhesion layer (120) and a metal comprised in the core (110) form an alloy in a region (121) adjacent to the surface of the core (110).

7. The object (100) according to any previous claim, comprising an outer layer (130) arranged on an outer surface of the adhesion layer (120), the outer layer (130) comprising a metal or metal alloy.

8. The object (100) according to claim 7, wherein the outer layer (130) comprises any of Cu, Sn, Au, Ag, Zn, Pd, Pt, and Rh, or alloys thereof.

9. A method for producing a metal object (100) according to any of claims 1 to 8, the object (100) comprising a core (110), the core comprising any of tungsten and molybdenum, the method comprising activating (S1) the surface of the core (110), rinsing (S2) the surface of the core (110), plating (S4) the core (110) with any of palladium, platinum, silver, copper, and rhodium, or alloys thereof, to form an adhesion layer (120), where the adhesion layer (120) has a thickness (t) equal to or less than 200 nm, rinsing (S5) the surface of the adhesion layer (120), and performing (S6) a heat treatment of the object (100).

10. The method according to claim 9, wherein activating (S1) the surface of the core (110) comprises performing an electrolytical etching procedure on the surface of the core (110).

11. The method according to claim 9 or 10 wherein performing (S6) a heat treatment of the object (100) comprises heating the object (100) to a temperature above 400 °C in the presence of a gas.

12. The method according to claim 11 , wherein the gas is an inert gas.

13. The method according to any of claims 9 to 12, comprising performing (S3) a heat treatment of the core (110) prior to plating (S4) the core to form the adhesion layer (120).

14. The method according to any of claims 9 to 13, comprising plating (S7) the object (100) to form an outer layer (130) on top of the adhesion layer (120).

15. The method according to claim 14, wherein plating (S7) the object (100) to form an outer layer (130) comprises plating the object (100) with any of Au, Sn, Cu, Ag, Zn, Pd, Pt, and Rh, or alloys thereof.

16. A machine (500) arranged to produce a metal object (100) according to any of claims 1 to 8.