DK2906733T3 - Material for electrical contact components - Google Patents

Description

Material for electriral contact components

The present invention relates to a material for a metal band for the production of electrical contact components according to the features in the preamble of patent claim 1 as w/ell as the use of such a material for an electrically conductive metal band for the production of electrical contact components according to the features of patent claim 5.

There are diverse possible applications for contact components in the area of electrical engineering as w/ell as electronics. As connection elements w/hich are mechanically combinable with each other as well as separable, their main problem consists in the production of an electrically conductive contact. Besides the closure of electric circuits direct couplings with electronic components are thus also realisable.

The respective design is oriented both to country-specific standards as well as to the requirements to be met in the area of application.

Thus, increased requirements are aiso placed on their mechanical load-bearing capacity particularly in the form of manuaiiy detachabie piug contacts.

High-grade piug contacts have a stable contact resistance, in which the preservation of the low transition resistance is paramount. A change of the contact resistance can be attributed mostly to the electrical breakthrough of the corrosion- or impurity iayer. in order to preserve an as durabie a contact surface as possibie for such contact components, the iatter often have a tin- or chromium coating or even a siiver- or goid coating.

For the production of such plug contacts mostly metal bands made from a copper alloy are used, from which the respective shapes are punched out. Depending on the amount used of the alloying partners zinc or tin which is used it is then a matter of either brass or workable bronze, such as, for example, CuSn4 to CuSnS. The latter material has an excellent bending property with medium strength. Since in this connection it is a matter of mixed crystal- or work-hardened materials, their resistance against relaxation is, however, relatively low. In addition, the bending property decreases significantly in the case of high strength conditions > R700 (Rm > 700 MPa, DIN EN 1173/95), which is reflected in larger bend radii with greater crack formation.

Since electrical contact components are mass-produced items, the purchase prices for the respective base material are of great significance. The respective content of copper within the alloy is crucial. Due to the high proportion of zinc in brass, copper alloys with a high proportion of copper therefore in contrast have a higher price by around 20%. A copper alloy for plug contacts is known from JP 2008/208466 A, which has a proportion of zinc (Zn) in weight percentage of 23% to 28%. Additional following components are represented with at least 0.01%, wherein silicon (Si) ranges up to a maximum of 3%, while nickel (Ni) constitutes a proportion of up to 5%. JP 2009/013499 A also discloses a copper material for plug contacts with a proportion of zinc (Zn) in weight percentage of 20% to 41%. The proportion of nickel (Ni) thereby ranges from 0.1% to 5.0%, wherein the proportion of tin (Sn) is from 0.5% to 5.0%. DE 103 08 779 B3 shows a lead-free copper alloy as well as its use. Its components in weight percentage are for copper (Cu) at least 60% to a maximum of 70% and thus quite high. In contrast, a proportion of nickel (Ni) of 0.01% to 0.5% is proposed, while the proportion of zinc (Sn) ranges from 0.5% to 3.5%. A possible proportion of silicon (Si) can range from 0.01% to 0.5%. US 4 362 579 discloses a copper material for electrical parts of 0.4 - 8 Ni, 0.1 - 3 Si, 10-35 Zn and the rest copper.

In particular, the high proportion of copper results in quite high purchase prices for the base material. Furthermore, the proportions of other alloy partners also offer more room for improvements in respect to improved material properties.

Therefore, the problem addressed by the present invention is to improve a material for a metal band for the production of electrical contact components so that despite the cost-effective proportions of its individual alloy partners the latter provide the necessary properties for use for an electrically conductive material for the production of electrical contact components.

The solution of this problem consists according to the invention in a material for a metal band for the production of electrical contact components according to the features of patent claim 1.

According to this, a material for a metal band for the production of electrical contact components, in particular of plug contacts, is proposed, consisting of a hardenable alloy with proportions in weight percentage of zinc (Zn) from 25.0% to 33.0%, tin (Sn) from 0.5% to 1.2% as well as nickel (Ni) from 0.8% to 2.5% and silicon (Si) from 0.1% to 0.6%.

In addition, the material can optionally have at least one element from the following group: phosphorus (P), boron (B), silver (Ag), manganese (Mn), chromium (Cr), aluminium (Al), magnesium (Mg), iron (Fe), zircon (Zr) or arsenic (As).

If all elements from the group are present, these form a maximum overall proportion of 4.55% of the material. In principle, none of the elements from the group in the event of its presence has a proportion of the total alloy exceeding 0.8%.

The remainder of the material is formed from copper (Cu) as well as melting-related impurities. Furthermore, the proportion of nickel (Ni) can at least partially be replaced by cobalt (Co). Thus, nickel (Ni) can also be 100% replaced and thus completely by cobalt (Co). The ratio of the proportions of nickel (Ni) and/or cobalt (Co) to the element silicon (Si) ranges from 3.5 : 1 to 7.5 : 1.

The metal band for the production of electrical contact components consists of the hardenable alloy CuZn30SnlNilSi0.2.

The particular advantage lies, in addition to the high content of zinc (Zn) and concomitant favourable production price, in the increased strength of the material. Compared with copper the increased strength is based on the mixed crystal formation. The solidification thus achieved is one of the possible strength enhancing processes, in order to obtain a hard material from an otherwise relatively malleable metal.

Furthermore, through precipitation hardening with nickel (Ni) - silicides a significantly higher strength can be achieved with good elongations and thus increased bendable property. This particularly compared with purely mixed crystal solidified and work-hardened special brasses, such as, for example, CuZn25Snl. In this way, in high strength conditions such as, for example, in the case of R780 (Rm > 780 MPa) an elongation at break Aso of > 3% can still be achieved (DIN 50125). The relaxation resistance is thereby significantly better than in the case of CuSn4 and CuZn25Snl.

Advantageous further developments of the basic inventive concept are the subject matter of the dependent patent claims 2 to 7.

According to these, the preferred proportion in weight percentage of the following can be: zinc (Zn) from 27.0% to 31.0%, tin (Sn) from 0.5% to 1.2% as well as nickel (Ni) from 0.8% to 2.0% and silicon (Si) from 0.1% to 0.6%.

The proportion of nickel (Ni) can be replaced at least partially by cobalt (Co).

For an optimal precipitation hardening a ratio of nickel (Ni) and/or cobalt (Co) to silicon (Si) from 3.5 : 1 to 7.5 :1 must be maintained. Preferably, this ratio can be from 4.0 :1 to 5.0 :1.

The optional presence of individual elements from the group in proportions in weight percentage in case of their presence is preferably: phosphorus (P) from 0.001% to 0.05%, boron (B) from 0.02% to 0.5%, silver (Ag) from 0.02% to 0.5%, manganese (Mn) from 0.03% to 0.8% chromium (Cr) from 0.01% to 0.7% aluminium (Al) from 0.02% to 0.5% magnesium (Mg) from 0.01% to 0.4%, iron (Fe) from 0.01% to 0.6% as well as zircon (Zr) from 0.01% to 0.4% and arsenic (As) from 0.001% to 0.1%.

The elements included in the group can be present optionally in the present material. Thus, phosphorous (P) and/or boron (B) can be added in the indicated amounts, wherein they serve as deoxidisers. Their presence has the effect that the oxygen (0) released in the melting is bound. In this way, the hydrogen brittleness is counteracted, while the formation of gas bubbles as well as oxidations of alloy components is prevented.

In addition, phosphorus (P) serves to improve the flow properties of the copper alloy present during the casting.

In case of the addition of manganese (Mn) primarily its solidifying property is used on the copper alloy. At the same time, manganese (Mn) also serves as a deoxidiser.

Through the addition of aluminium (Al) the hardness of the material is increased as well as its elongation limit. The said positive increases are thereby not accompanied with reduction of the toughness of the material. Overall the addition of aluminium (Al) serves to improve the strength, workability as well as the wear resistance and the oxidation resistance of the alloy at high temperatures.

The addition of chromium (Cr) and magnesium (Mg) serves to improve the oxidation resistance at high temperatures. In this connection, better results can be achieved, while chromium (Cr) and magnesium (Mg) are mixed with aluminium (Al).

The addition of iron (Fe) at the previously identified level has a grain-refining and overall solidifying effect. Iron phosphides are formed in connection with phosphorous (P).

Through the addition of zircon (Zr) the hot formability of the material is improved.

Furthermore, the addition of arsenic (As) brings about a reduction of the dezincification tendency.

As a result, a copper material is shown, which permits a cost-effective possibility for the production of electrical contact components on the basis of its low proportion of copper. Despite the low proportion of copper (Cu) the necessary properties for use for an electrically conductive material for the production of electrical contact components are nevertheless provided. The copper material thus generated can be used in the form of metal bands, which serve for the production of electrical contact components.

Furthermore, the invention shows a use of copper material for an electrically conductive metal band. The metal band serves for the production of electrical contact components, in particular, of plug contacts.

Depending on the requirement, the metal band thus used can be tin-plated on the surface. In an alternative design the metal band used can have a tin-silver layer (SnAg).

Claims (7)

1. Material of a metal strip for the manufacture of electrical contact components, in particular electrical sockets, consisting of an age-cure copper alloy having the following weight percent alloy components: Zinc (Zn) 25.0% to 33.0% Tin (Sn) 0.5 % to 1.2% Nickel (Ni) 0.8% to 2.5% Silicon (Si) 0.1% to 0.6%, optionally at least one element of the following group: phosphorus (P), boron (B ), silver (Ag), manganese (Mn), chromium (Cr), aluminum (Al), magnesium (Mg), iron (Fe), zirconium (Zr) or arsenic (As) where the proportion of an individual element of the group is at most 0.8% and the proportion of all elements of the group is at most 4.55%, and the remainder is copper (Cu) and impurities originate from the melting process, where nickel (Ni) can be at least partially replaced by cobalt (Co), and the ratio of nickel (Ni) and / or cobalt (Co) to silicon (Si) ranges from 3.5: 1 to 7.5: 1. Material according to claim 1, characterized by a percentage by weight of Zinc (Zn) 27.0% to 31.0% Tin (Sn) 0.5% to 1.2% Nickel (Ni) 0.8% to 2 , 0% Silicon (Si) 0.1% to 0.6%, where nickel (Ni) can be at least partially replaced by cobalt (Co). Material according to either claims 1 and 2, characterized in that the ratio of nickel (Ni) and / or cobalt (Co) to silicon (Si) is from 4.0: 1 to 5.0: 1. Material according to any one of claims 1 to 3, characterized in that the optional elements in the group, when present, correspond to the following percentages by weight: Phosphorus (P) 0.001% to 0.05% BOr ( P) υ, υζ 7o III U, 0 7o Svoi (Ag) 0.02% to 0.5% Manganese (Μη) 0.03% to 0.8% Chromium (Cr) 0.01% to 0.7% Aluminum (Al) 0.02% to 0.5% Magnesium (Mg) 0.01% to 0.4% Iron (Fe) 0.01% to 0.6% Zirconium (Zn) 0.01% to 0, 4% Arsenic (As) 0.001% to 0.1%, Use of a material according to any one of claims 1 to 4 for an electrically conductive metal strip for the production of electrical contact components, in particular electrical outlets. Use of a material for an electrically conductive metal strip according to claim 5, characterized in that the metal strip is tinned. Use of a material for an electrically conductive metal strip according to claim 5 or 6, characterized in that the metal strip has a tin-silver layer.