JPH067452B2 - Power connector - Google Patents

Abstract

Electric power connectors made with at least one contacting component having a gold contacting surface wherein the gold contacting surface is metallurgically bonded to an underlying layer of nickel or nickel-rich alloy . At the contact surface the gold contains a total of about 1-10% by weight nickel with the amount of nickel generally increasing in the direction from the surface to the underlying metal the increase starting at a point inward of and remote from the contacting surface.

Description

Description: FIELD OF THE INVENTION The present invention relates to electrical connectors or contacts, and more particularly to electrical connectors useful in carrying substantial currents, perhaps at voltages above 10V.

[Background of the Invention]

It is known in electronic technology, especially computer technology, to use pure gold electronic contacts to reduce the contact resistance of the normally spring-partitioned contact surfaces to be joined to a minimum value that cannot be further reduced. Such contact surfaces, which have a contact resistance of less than 1 mΩ when tested against a lightly polished gold probe, are generally not designed for frequent opening and closing. Thus, thin pure gold contact surfaces on circuit boards and their interlocking parts are often the standard means for providing electrical circuits in electronic and computing devices operating at voltages up to only 100 mV, extremely low amperages. Such contacts are very resistant to corrosive media and oxidation.
However, if gold is used on some metal substrates, such as copper or silver, without an intermediate layer of nickel, the electronic contacts will degrade if exposed to temperatures above 25 ° C, on the order of 100 ° C. Tend to do. Copper and silver atoms gradually migrate to the gold surface. Transferred copper creates a contact surface that is susceptible to sulfidation and oxidation, while transferred silver is particularly detrimental when the contact surface is used in a sulfidation atmosphere as mild as normal room air. Therefore, a layer of nickel (or optionally cobalt or a nickel-rich alloy or a cobalt-rich alloy) is used between copper or silver or a copper-based alloy or silver-based alloy substrate and gold and copper or silver. It is common standard Pfukutis to prevent migration and to provide an exposed layer of relatively tarnish resistant metal where there may be fracture in the upper layer of gold. A good description of electronic type contact materials is contained in the article "Inlay Clad Alloy Alloy Properties", Robert Jay Russell, Solid State Technology, page 10 (876).

There is a need for electrical contact materials that have low contact resistance, but not necessarily the extremely low contact resistance required by the electronics industry, and sufficient abrasion resistance to survive high frequency switching.

It is an object of the invention to provide an electrical contact suitable for carrying reasonably high amperages, in some cases with voltages above 10V.

Yet another object of the present invention is to provide an electrical contact material that can be used in the electrical contact of the present invention.

[Outline of Invention]

The present invention is suitable for providing a breakable conduction path for an electric current (for example, an electric current of at least about 0.1 A) characterized in that it comprises at least two components arranged in surface contact with each other. Intended for power connector. At least one of these components has a mating contact surface made from an alloy of gold and nickel. At the bond interface, the alloy contains from about 1 to about 10 weight percent nickel. The amount of nickel in gold generally increases with distance from the mating interface to the metallurgically bonded underlayer of essentially pure nickel. However, alloys prepared by diffusing nickel from the bottom layer to the top layer of gold usually have the following properties when examined by sputtering and Auger analysis:
Indicates a particular structure. Very close surface, sometimes 1
The 50 Å unit surface has a relatively high nickel content. Immediately below this surface layer, the nickel content is slightly reduced and in some cases 0.3 to 2 μm of the thickness of the gold layer
It remains relatively constant up to 3. Over the remaining thickness of the gold-containing layer, the nickel content increases rapidly to the nickel content of the underlying metal. Those skilled in the art will recognize that this type of Auger analysis sometimes gives results at the surface of the inspected object that may be surface artifacts and may not represent the properties of the bulk material or may be insignificant with respect to the properties of the bulk material. Will. Therefore, in the gold layer of the contact structure of the present invention, it can be said that the nickel content near the outer surface is at a relatively low level. that is,
At some point away from the surface, it remains at a low level until the nickel content of gold increases rapidly.

The power connector can be in the form of conventional contacts such as male / female plug parts, pins, threaded structures and the like. Advantageously, the connector has a shape such that it can be made from a strip of electrical contact composite material. Such contact materials, which are also within the contemplation of the present invention, include conductive materials such as
Of a metal having at least one major surface consisting of nickel or a nickel-rich alloy underlying a gold layer having a thickness of about 0.1-2 μm metallurgically bonded to nickel or a nickel-rich alloy A strip-shaped structural substrate is provided. This diffusion is about
Such as giving about 10% by weight. In this context, "nickel-rich alloy" means an alloy containing at least about 90% nickel, preferably at least 95% or 99% nickel and is commercially pure nickel and nickel-cobalt alloys. Includes.

Specific examples of contact materials of the present invention include copper, copper-based alloys such as brass, cupronickel, beryllium copper, copper-nickel-tin alloys and copper-nickel-aluminum alloys, nickel, cobalt or nickel-cobalt alloys ( In particular, a strip form) can be mentioned. In the case of copper, copper-based alloys and cobalt, the base metal has an electrodeposited layer of nickel with a thickness of about 3-10 μm on at least one major surface. The outer portion of the at least one major surface has a thickness of about 0.1 to about 2 μm of electrodeposited gold or gold alloy containing up to about 1% total nickel and / or cobalt.
The electrodeposited gold or gold alloy layer is thermally bonded to nickel to provide diffusion of nickel to the gold surface in an amount of about 1% to about 10% total nickel at or near the surface. The strip can face the gold on all surfaces, or on two major surfaces, namely the top and bottom surfaces, or on one major surface.

Nickel and nickel-rich alloy strips are prepared by conventional metallurgical melting technology in which the metal charge is melted, then cast, and then hot worked and / or cold worked into strip form. be able to. A particularly advantageous method of making nickel, cobalt or nickel-rich alloy strips is to roll-compact metal powders, sinter bond them, roll compact metal powders after interdiffusion and at the same time roll the bonded powder product into strips. It is a method of forming the shape and the thickness.

The strips of metal other than nickel or nickel-rich alloys that can form the primary structural element of the connector of the present invention are generally prepared in a conventional manner and are commercially available from many suppliers. The present invention is copper, brass, aluminum bronze,
The use of commercially available strips of cupro nickel, beryllium copper, copper-nickel-tin alloys and other metals or other electrically conductive materials useful in electrical contact technology is contemplated. The strip is thoroughly cleaned by conventional methods such as alkaline cleaning bath, solvent, steam degreasing, and then electroplated to provide a layer of nickel about 5 to about 10 μm thick. Electroplating Engineering Handbook, 3rd Edition, A.M. Kenneth Grahan, Van Nostrand
One of the electroplating baths described by Reinhold Company, Copyright 1971, p. 247, can be used to electroplate nickel.

Gold is electrodeposited on nickel strip or plated nickel from a cyanide, citrate or other type of bath suitable for producing pure soft gold electrodeposits. The strip is then heated at about 350 ° C to 600 ° C for 2 hours to 1
Heat treatment for 0 seconds to diffuse nickel into gold to reach an amount of 1-10% nickel on the gold outer surface.

Electrical connector materials and electrical contacts made therefrom, as contemplated by the present invention, are essentially free of corrosion products and remain essentially free of corrosion products throughout their useful life, and thus reliable. It is advantageous over base metal contacts because it provides some stable contact service. When passing high currents (e.g. higher than 0.1 A) into an electrical circuit as compared to a pure gold contact surface, the contacts and contact materials of the present invention are advantageous when the contacts must be periodically opened. is there. In these situations, the pure gold surface is abraded or roughened, the gold on the gold contact surface tends to sinter or melt together, and the contacts cannot be easily separated. Conversely, the present invention provides that the modified gold on such modified gold contacts does not exhibit the melting or sintering characteristics of pure gold when the gold contact surface contains 1-10% nickel, and, of course, includes contacts. In this way, the contacts are based on the finding that the contacts can be easily opened at all times, provided that the circuit has not been overloaded beyond a predetermined capacity.

In preparing the contact materials of the present invention, those of ordinary skill in the metallurgical arts will recognize that heat treatment times will typically vary with temperature (longer times will yield gold of a given thickness). If used at lower temperatures, vice versa or the same). Lower temperatures and shorter times at a given temperature would be used for thinner gold layers than for thicker gold layers. As disclosed in co-pending Canadian Patent Application No. 534,009, the diffusion of nickel into gold is
It can be performed at the same time as age hardening of the age hardening substrate. Normal,
For example, beryllium copper, copper-nickel-tin alloy, copper-
This age hardening of copper-based alloys such as nickel-aluminum alloys is performed after the contact material is in its final form as an electrical contact. For example, a beryllium copper strip form is blanked and formed into a contact shape. The contacts thus formed are then sequentially electroplated with nickel, gold, and then the thickness of electroplated gold to achieve both age hardening of the substrate and proper gold-nickel interdiffusion simultaneously. The heat treatment is performed at a temperature / time combination selected in consideration of the above. Alternatively, the contacts may be blanked from a composite gold-nickel-copper beryllium strip, molded, and then heat treated.

The annealing heat treatment that results in the diffusion of nickel and gold can be performed concurrently with the hot rerolling of the plated strip material. For example, a nickel strip made by roll compacting, then sintering, and rolling nickel powder is electroplated with gold and then 350 ° C-500.
It can be rerolled at a temperature in the range of ° C to enhance the metallurgical bond between nickel and gold and to effect nickel diffusion. Alternatively, metallurgical bonding and diffusion can be achieved by annealing heat treatment as described above and the composite can be cold rolled either before or after annealing to enhance mechanical properties.

〔Example〕

The following examples are given in order to give those skilled in the art a greater appreciation of the advantages of the present invention.

Roll compaction made from sintered nickel powder about 0.5 thickness
mm, width about 30 mm, length about 70 m, thoroughly washed, mildly etched, electroplated with gold from a citrate-based electroplating bath to a uniform thickness of about 0.5 μm Give a pure gold deposit. Rinse the plating strip thoroughly to remove traces of electrolyte,
Dry and then heat treat by passing through an oven. Hold the furnace at 480 ° C. The furnace contains an atmosphere of 10% by volume hydrogen with the balance being nitrogen. The cooling strip is fed into the furnace and passed through with a residence time of 6 minutes. When the strip exits the furnace, it cools under the same reducing conditions, then
Roll up.

The composite nickel-gold contact material prepared in this way gives excellent results in electrical contact service composites versus composites. The contacts show essentially no deleterious behavior over time when exposed to normal service. The contacts do not corrode in service, do not rub, do not pit, and can be cut hundreds of times without difficulty even when exposed to temperatures up to about 200 ° C. in use.

While particular aspects of the invention have been illustrated and described herein according to the terms of the statute, those skilled in the art can make changes in the form of the invention covered by the claims and the correspondence of other features. It will be appreciated that certain features of the invention may sometimes be used to advantage without the use of.

Front Page Continuation (72) Inventor Bruce, Randolph, Connard, Ontario, Canada, Oakville, Baltham, Drive, 153 (72) Inventor Jurage, Babjak, Ontario, Mississauga, Louise, Drive, 671 (56) ) References JP-A-61-233912 (JP, A)

Claims (1)

[Claims] 1. A power connector comprising at least two components arranged in surface contact with each other, at least one of the components having a mating contact surface made from an alloy of gold and nickel, The alloy of gold and nickel has a nickel alloy substrate, the nickel alloy substrate having an electrodeposited nickel intermediate layer having a thickness of 3 to 10 μm and a thickness of 0.1 to 2 μm on the electrodeposited nickel intermediate layer.
m electrodeposited with pure gold, the electrodeposited metal being 1 to 10% by weight of nickel near the joint contact surface.
And the amount of nickel remains substantially constant over some distance from the surface, and at a point inside the joint surface, consisting of gold-containing metal and electrodeposited nickel with the distance from the joint contact surface. A power connector having a breakable conductive path for electric current, characterized in that it is starting to increase towards the interface between a metallurgically bonded underlayer.