KR930009233B1 - Nickel based electrical contact - Google Patents

Abstract

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Description

[Name of invention]

Nickel Base Electrical Contacts

[Brief Description of Drawings]

1 is a perspective view of an electrical connection device according to the present invention.

2 is a schematic cross-sectional view of a portion of an electrical connection device according to the invention.

Detailed description of the invention

[Technical Field]

The present invention relates to electrical contacts, in particular nickel-based electrical contact materials.

[Background]

In general, gold has been used in the manufacture of high quality electrical contacts, which has a low contact resistance and high chemical stability, which has advantages in the art. However, gold is expensive and efforts have been made to find other materials for making contacts.

Remarkable among other materials, however, are precious metals other than gold, for example silver-palladium alloys known to be suitable for specific applications. These other alloys are cheaper than gold, but still require lower costs, and inexpensive metal alloys such as copper-nickel alloys have been the subject of long-term contact resistance and stability studies. This is referred to the "Contact Characteristics of Nickel-Containing Alloys" in the 1972 [Electrical Contacts] of the Illinois Institute of Technology, S.M.Garte et al.

Overview of the Invention

It has been found that some nickel alloys have contact properties of high stability and low contact resistance comparable to gold. The device according to the invention comprises a contact surface made of an alloy consisting of nickel and at least one of glass-forming additive elements such as boron, silicon, germanium, phosphorus, arsenic, antimony or bismuth. The presence of such a glass phase forming element prevents the formation of nickel oxide, which is a semiconductor, or forms a thermodynamically more stable compound that maintains the metallic conductivity of the contact layer in an oxidizing atmosphere.

The addition of one or more vitreous elements results in crystallographically disordered tissue, at least when the layer is exposed to the oxidizing atmosphere, in contrast to the formation of crystalline nickel oxide without the appropriate addition of vitreous elements. to be. Optionally, crystallographically disordered tissue may also be obtained by ion bombardment, in which alpha particles are readily utilized.

Surface contact resistance is generally kept below 100 milliohms even after prolonged exposure to oxidation.

The electrical connection device shown in FIG. 1 includes a housing 11 and a contact piece 12. The housing 11 is made of an electrically insulating material, and the contact pin 12 has a contact surface according to the present invention.

In the cross-sectional view of FIG. 2, an electrically conductive member 21 disposed below the surface layer 22 is shown. The surface layer 22 according to the present invention is made of an alloy of nickel with at least one glass phase forming element. When exposed to an oxidizing atmosphere, part 23 of surface layer 22 contains oxygen.

Suitable glass-forming additives include boron, silicon, germanium, phosphorus, arsenic, antimony and bismuth, and the amount of such elements present in the contact layer is preferably from 1 to 40 atomic% relative to the total amount of nickel and additive elements combined. The range of 2 to 10 atomic%, and the range of 25 to 35 atomic% at which a thermodynamically stable and stoichiometric compound is formed is also a good range.

Nickel and one or more glass forming additive elements in the compound constitute a good amount of at least 70 atomic percent with respect to the contact layer material. In order to obtain improved electrical and mechanical contact properties, the addition of cobalt is preferred, and elements other than cobalt are preferably limited to an amount of 5 atomic% or less, preferably 1 atomic% or less in the compound. Particularly bad is the presence of elements of Group VI, such as sulfur, selenium and tellurium, and the compounding amount of these elements is preferably limited to 0.5 atomic percent or less.

In the case of nonstoichiometric aggregates, the addition of a glass-forming additive to nickel is thought to prevent the formation of nickel oxide, which is a semiconductor, in the oxidation atmosphere. It is believed that in the case of the addition of the glass-forming additive, a surface layer of the aggregate containing nickel and oxygen and the glass-forming additive is formed in a sufficiently large area in place of such a semiconductor nickel oxide, and such an assembly has almost metallic conducting properties. . Based on the paper, the thickness of the oxygen-containing surface layer appears to be on the order of 2.5 nanometers.

In the nickel-containing layer, the crystallographic disorder is also generated by the ion bombardment. The ion bombardment generates the crystallographic disorder even before exposure to the oxidizing atmosphere. Likewise, such a tissue is a disordered, quasi-amorphous, oxidized surface portion that is believed to conduct with the desired low contact resistance of the contact layer for use in an oxidizing atmosphere. The crystallographic disordered nickel aggregate preferably comprises at least 50 atomic percent nickel.

The following example illustrates in detail the stability of the contacts according to the invention.

[Example 1]

A surface contact resistance was measured using a standard four-point probe with a getter-sputtering technique of a layer consisting of nearly 95 atomic percent nickel and 5 atomic percent antimony on a copper substrate with a thickness of about 3 micrometers. 5-7 milliohms. The attached thin film was then tested for stability at high temperature and humidity (65 hours at 75 ° C., 95% relative humidity) with subsequent contact resistance found to be 15-20 milliohms.

[Example 2]

An experiment similar to Example 1 was performed on a layer consisting of almost 95 atomic percent nickel and 5 atomic percent phosphorus. The contact resistance was 1.8 milliohms before the stability test and 4.4-5 milliohms after the test.

Example 3

An experiment similar to Example 1 was conducted on a layer consisting of nearly 95 atomic percent nickel and 5 atomic percent boron. The contact resistance was 2.9 to 3.5 milliohms before the test of stability as described above and 10 to 14 milliohms after the test.

Example 4

An experiment similar to Example 1 was conducted on a layer consisting of nearly 95 atomic percent nickel and 5 atomic percent silicon. The contact resistance was 1.6 to 2.1 milliohms before the test of stability as described above and 4.5 to 6 milliohms after the test.

Example 5

An experiment similar to Example 1 was performed on a layer consisting of nearly 95 atomic percent nickel and 5 atomic percent germanium. The contact resistance was 1.5-1.85 milliohms before the test of stability as described above and 10-14 milliohms after the test.

Example 6

An aqueous solution containing 209 g / l of NiCl ₂ , 6H ₂ O, 49 g / l of 85% H ₃ PO _4, and ₅ g / l of H ₃ PO ₃ was prepared. The solution was used for preplating on a copper electrode at a temperature of 75 ° C. in the plating bath, a current rating of 150 mA / cm 2, and a plating rate of about 3 micrometers / minute. The attached layer was about 4.5 micrometers thick. The contact resistance of the deposited layer was less than 10 milliohms after the same stability test.

Example 7

An aqueous solution of 0.087 mol of As ₂ O ₅ and 0.5 mol of NiCl _2.6 H ₂ O was prepared. The copper electrode was plated with nickel arsenide by pulse plating from the solution at a temperature of 75 ° C. and a current pulse of 200 mA / cm 2 turned on for 1.5 seconds and off for 0.5 seconds. The thickness of the layer attached was about 4.5 micrometers. The contact resistance of the deposited layer was less than 10 milliohms after the same stability test.

Example 8

To a solution containing 5 g of GeO ₂ in 4 cc of ammonium hydroxide 4 cc + water, 0.5 mol of NiCl _2.6 H ₂ O and 150 g / l of ammonium citrate were added. The solution was filtered and ammonium hydroxide was added until the pH reached 8.5. From the solution, a nickel-germanium layer was plated on a copper electrode at a temperature of 75 ° C., a current density of 150 mA / cm 2, and a plating rate of about 2.5 micrometers / minute. The thickness of the layer attached was about 4.5 micrometers. The contact resistance of the deposited layer was less than 10 milliohms after the same stability test.

Example 9

A nickel layer having a thickness of about 305 nanometers was attached to the smooth copper foil. Portions of the nickel layer were covered with a thin aluminum plate and α particles were injected into the uncoated portion of the nickel layer. The α particles had an energy of about 1.8 MeV and about 1.6 × 10 ¹⁷ particles / cm 2 dose to have a minimum contact resistance (less than 10 milliohms) after testing stability at high temperatures as described in Example 1 This proved to be optimal (this test is believed to be significant for exposure to normal atmospheric conditions for five years). In addition, in the visual inspection comparing the part injected with α particle and the part coated with aluminum foil after the test, the part injected with α particle was bright and shiny while the part coated with aluminum plate was dark and brown.

Claims (11)

A nickel basic electrical contact, wherein the surface of the body comprises an electrical contact made of a contact material, wherein the contact material is a crystallographically disordered structure and the basic amount of nickel constitutes a major part of the total amount. 2. The nickel basic electrical contact as claimed in claim 1, wherein said contact material is a crystallographic disordered structure generated by ion bombardment. The contact material according to claim 1 or 2, wherein the contact material comprises at least one additional element and nickel selected from silicon, germanium, phosphorus, arsenic, antimony and bismuth of boron, and the at least one additional element is in the contact material. The nickel basic electrical contact is present in an amount in the range of 1 to 40 atomic% of the compounding amount of nickel and the at least one additional element, wherein the compounding amount is 70 atomic% or more of the contact material. 4. The nickel basic electrical contact as claimed in claim 3, wherein said crystallographically disordered structure occurs upon exposure of the contact material to an oxidizing atmosphere. 4. The nickel basic electrical contact according to claim 3, wherein the amount of sulfur, selenium and tellurium in the compound is limited to 0.5 atomic% or less with respect to the contact material. 4. The nickel basic electrical contact as claimed in claim 3, wherein the contact resistance of the surface of the body of the contact material is 100 milliohms or less. 4. The nickel basic electrical contact as claimed in claim 3, wherein the body of the contact material is in the form of a layer attached on the substrate. 2. The nickel basic electrical contact as claimed in claim 1, wherein the contact material additionally contains cobalt. 4. The nickel basic electrical contact as claimed in claim 3, wherein the at least one additional element is boron, phosphorus or arsenic. 4. The nickel basic electrical contact as claimed in claim 3, wherein the at least one additional element is silicon or germanium. 4. The nickel basic electrical contact according to claim 3, wherein the at least one additional element is antimony or bismuth.

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