DE102010042526A1 - contact element - Google Patents

Abstract

The invention relates to a contact element made of a base material with at least one conductive layer applied thereon, made of indium or indium with an admixture or alloy of at least one of the elements from the group of elements containing copper, silver, gold, bismuth, nickel, antimony Palladium, iron, carbon and phosphorus exist.

Description

In electrical and electronic apparatus and devices, electrical connections between various electrical and / or electronic components of the apparatus and devices often have to be made, which in many cases consist of permanent solder joints.

However, it is becoming increasingly common to provide connectors, in particular in the connection of electrical and / or electronic components with printed circuit boards plug-in connections are used by press-fitting. In this case, a preferably elastic press-fit pin is pressed into a bore of the printed circuit board. Depending on the materials used and the applied pressing force reliable electrical connections are created. Both the press-fit pin and the opening or socket receiving it must be coated with a suitable electrically conductive material, so that a reliable and stable electrical contact is achieved during insertion or insertion. Suitable contact elements include press-in zones, plug contacts, insulation displacement contacts (IDC) and crimp contacts.

It has been and still is quite common to use tin / lead-containing materials for the surface coatings because they are sufficiently soft to ensure good bonding of the contact elements and to prevent whisking of the tin due to the lead content. However, due to legal requirements, the lead content must be reduced or even completely eliminated. Due to the high tin content then there is a high risk of whisker formation, which brings the problem of short circuits with it.

The DE 10 2007 047 007 A1 proposes to solve this problem an electrical contact element and a method for producing the same, in which an alloy of tin and at least one other metal from a group of metals is used as the outermost layer of a layer structure in a contact element. Due to the still existing pure tin in the structure, however, the risk of whisker formation is retained.

The object of the present invention is therefore to provide a contact element in which the risk of whisker formation is largely eliminated.

The object is achieved by a contact element made of a base material with at least one conductive layer applied thereto, wherein a layer of indium is applied as the conductive layer or one of these layers. In this case, pure indium is preferably applied by electroplating, where indium with technologically determined impurities is to be understood as pure indium.

The object is also achieved by a contact element made of a base material having at least one conductive layer applied thereto, wherein as the conductive layer or one of these layers is a layer of indium with an admixture or alloy of at least one of the elements from the group of elements containing copper, silver , Gold, bismuth, nickel, antimony, palladium, iron, carbon or phosphorus is applied. The mixture or alloy can be carried out before the application of the layer, but also by applying the metal layers in succession and subsequent alloying, for example by a heat treatment.

By the contact elements according to the invention is a potential solution to the requirement for lead-free End of Life Vehicle Directive, 2000/53 / EC solved for "Compliant pin connecting systems". In particular, can be dispensed with tin or a lead-free tin alloy, as these show whisker growth. Due to the absence of tin, melting of the layer below typical application temperatures in automotive technology of up to 150 ° C is also excluded. The lowest melting point for tin-indium alloys is significantly lower than this 150 ° C.

In one development of the invention, between the base material of the contact element and the conductive layer, an intermediate layer may be applied as a diffusion barrier of at least one of the elements of the group of elements containing nickel, copper, iron and tungsten.

As a base material comes in contact plugs or Einpressstiften a metal such as bronze, brass, copper, nickel or copper-nickel-silicon alloys and copper-iron in question.

In one development of the invention, at least one further conductive layer of copper, silver, gold, bismuth, nickel, antimony, palladium or carbon can be applied to the conductive layer.

Alternatively, an organic protective layer can be applied as corrosion protection.

The deposition or depositing of the metallic layers can be carried out in a galvanic, chemical or melting manner as well as by molecular or gaseous deposition.

Depending on the selected material, the material thickness and the ratio of the diameters of the contact pins or press-fit pins and the sockets, the contact elements according to the invention can form non-detachable connections due to cold welding, but also partially detachable or repeatedly detachable contacts for repair purposes.

By the contact elements according to the invention thus a tin and thus a tin-whisker-free coating is proposed, which also meets the required lead-free.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007047007 A1 [0004]

Cited non-patent literature

• End of Life Vehicle Directive, 2000/53 / EC [0008]

Claims (6)

Contact element made of a base material with at least one conductive layer applied thereto, characterized in that a layer of indium is applied as the conductive layer or one of these layers. Contact element of a base material having at least one conductive layer applied thereon, characterized in that as the conductive layer or one of these layers, a layer of indium with an admixture or alloy of at least one of the elements from the group of elements containing copper, silver, gold, bismuth , Nickel, antimony, palladium, iron, carbon and phosphorus is applied. Contact element according to one of claims 1 or 2, characterized in that between the base material and the conductive layer, an intermediate layer is applied as a diffusion barrier of at least one of the elements from the group of elements containing nickel, copper, silver, iron and tungsten. Contact element according to one of Claims 1 to 3, characterized in that a thin layer of copper or of a copper alloy is applied directly to the base material. Contact element according to one of claims 1 to 4, characterized in that on the conductive layer at least one further conductive layer of copper, silver, gold, bismuth, nickel, antimony, palladium or carbon is applied. Contact element according to one of claims 1 to 4, characterized in that an organic protective layer is applied to the conductive layer.