GB2112417A

GB2112417A - Solderable iron wire and method for its production

Info

Publication number: GB2112417A
Application number: GB08236726A
Authority: GB
Inventors: Dietrich Ascher; Dr Heinz Hiesbock; Eduard Sulzer
Original assignee: NEUMAYER KARL GmbH
Current assignee: NEUMAYER KARL GmbH
Priority date: 1981-12-30
Filing date: 1982-12-23
Publication date: 1983-07-20
Also published as: GB2112417B; DE3246920A1; AT373188B; JPS58165211A; NL8205054A; ATA565681A

Abstract

There is disclosed a cheap solderable wire replacement for copper wire in which an interpenetration barrier layer (2, 3) is applied to an iron wire core (1) and a coating (4) of tin or a tin-lead alloy is applied to the barrier layer. The barrier layer is preferably of copper or nickel and is generated galvanically. The bonding of the tin layer with the iron core is such that the wire conforms with soldering test standards, the adhesion of the soldering tin to the barrier layer proving to be surprisingly reliable even after artificial aging. <IMAGE>

Description

SPECIFICATION Solderable iron wire and method for its production The invention relates to a solderable iron wire with nickel and tin coatings.

For the production of the wiring of electric circuit arrangements and for connection leads for passive electronic components it is known from Swiss Pat. Sp. 310,839 and 310,840 or Fed.

German Pub. Sp. 1,082,094 to use coated, especially tin-coated, copper wires. Copper is easily workable and has a very high electrical conductivity value, and when used as feed wire on the passive component it is significant cost factor.

However in present-day electronic circuit arrangements an extremely good electric conductivity of the wirings and connection wires of electronic components mostly brings no advantage. A specific ductility and satisfactory solderability of the conductor wires are of primary importance. Experiments by the Applicants with tin-coated iron wires of low carbon content have shown that while such tin-coated wires can be soldered well after tinning, after lengthy storage or artificial ageing they are no longer wetted by the molten solder in the soldering operation, because the surface tin layer merges, due to storage or ageing, into an iron-tin phase having dewetting properties.

Heavy current leads are also known which have an iron wire core plated with an outer copper layer. In these known leads, from which for example conductor cables for high-tension conductor systems are produced, the current conduction function is taken over essentially by the outer copper layer, while the tensile strength of the conductor is mainly determined by the iron wire core. In contrast thereto, in the object of the invention the thin copper layer applied galvanically to the iron wire core contributes only insubstantially to the overall conductivity of the conductor.

The invention aims at a solderable wire with a cheap iron core, it being intended that the iron core should be cheaper than copper wire, in which the solderable applied layer is resistant to heat storage, in accordance with soldering standards, and is stable. This aim is achieved in that an interpenetration barrier layer is applied galvanically directly to the iron wire and a tin coating or tin-lead alloy coating is applied to this layer.

More especially it is proposed that the interpenetration barrier layer is a layer of copper and/or nickel. Surprisingly it has appeared that a very thin interpenetration barrier layer can be generated by the galvanic application and this layer, that is the copper layer and/or nickel layer, and also the tin layer bonds with the iron core in a heat-storage-resistant manner and in accordance with soldering standards, and a wire conforming with the test standards for soldering is obtained which, thanks to the iron core and the thin nickel or tin layer, can be produced at a substantially more favourable price than conventional solderable wires. The adhesion of the soldering tin to the galvanically applied layers surprisingly is reliably present even after artificial ageing.

It is further proposed that the copper layer applied galvanically to the iron wire has a thickness of 0.5 to 4 ju preferably 2 y.

According to a further proposal of the invention the thickness of the nickel coating amounts to 0.5 to 4 ju, preferably 2 y.

It is further propsed that the thickness of the tin layer amounts to 3 to 10 , preferably 5 y.

Such thin material coatings can be applied at favourable cost only galvanically. The wire according to the invention consists essentially of the cheap iron core, preferably of low-alloyed iron wire with a carbon content of 0.03 to 0.1%, but it is also possible to use another iron core for special purposes and very thin copper, nickel and tin layers, so that the consumption of expensive non-ferrous metals is low and thus the price of the overall product can be kept low, although surprisingly the end product is in complete conformity with the soldering standard.

By wire there is of course understood not only round wire but also flat wire, wire with square cross-section, wire with rectangular cross-section or profiled wire with any desired cross-section. All these wires can be treated galvanically. Of course it is possible in place of an iron core with low carbon content to use wires alloyed in accordance with other strength requirements or material properties. More especially it is also possible, for special purposes, to coat non-magnetic iron, in which case a thin coating of special profile sections is also possible.

It is especially possible in the case of the galvanic production to obtain a precise and economical dimensioning of the layers and to achieve a uniform coating.

The invention is explained in greater detail by reference to an example of embodiment represented in the drawings, without being limited thereto.

Figure 1 shows a part of a solderable wire diagrammatically in enlarged oblique view and section, it being possible to show the coating only in enlarged manner for reasons for draughtman Ship.

Figure 2 shows a galvanic production plant diagrammatically.

Figure 3 shows a view from above of a variant of an installation in which three wire lengths each of six wires side by side are arranged in sequence in different treatment stations.

The wire as shown in Figure 1 consists of an iron core 1, of an iron with a carbon content of 0.05%, which is inherently weldable. Upon this iron core there is galvanically applied a copper layer 2 with a thickness of 2,u and above this a nickel layer 3, with a thickness likewise of 2 ,u.

The outermost coating consists of an applied tin layer which has a thickness of 5 ju. As may be seen from Figure 2, the iron wire is conducted from an iron wire supply reel 5 into a galvanic copper bath with accessories, such as downward device etc., in which the copper layer 2 is applied.

Then in a nickel bath 9 of a galvanic nickel application plant the nickel layer 3 is applied, and then a tin bath the tin layer is applied likewise galvanically, whereupon the finished wire is wound up on the take-up reel 10.

In the embodiment according to Figure 3 a part of a complete galvanisation plane is shown in greater detail. In this plant three wire lengths each of six wires are provided one above the other, and parallel, several baths being arranged one behind the other. The wire runs firstly through analogous degreasing stations, then with a rectilinear passage through a pickling station, which is filled with 10% hydrochloric acid at 20 C. These stations are not shown.Thence the wire runs into the copper-plating station 13, in which copper is applied at 400C. with 800 A with an immersion length of 4.5 m., to a thickness of 1 14. In the following pickling station 14 the wire is treated with sulphamic acid and then comes into a nickel bath 15 where a nickel coating of 2 y is applied with 2000 A and a dipping length of 9 m., the anode-cathode voltage amounting to 12 v. The wire further passes by way of a further pickling station into an analogous tin bath (not shown) in which a tin coating 4 ,u in thickness is applied with 2,000 A and a dipping length of 12 m. After a treatment with hot water the wire is wound on reels. The starting wire stock is here an iron wire, the end product is a solderable wire.

It has resulted that the galvanic application brings good results. Of course within the scope of the invention it is also possible to use other coating application methods; thus by way of example it would be possible to draw the nickelcoated wire through a tin bath, and in place of a tin bath similar solderable alloys can also be used.

Claims

1. Solderable iron wire with nickel and tin coatings, characterised in that an interpenetration barrier layer is applied directly galvanically upon the iron wire (1) and a tin layer (4) of a tin-lead alloy layer is applied upon this barrier layer.

2. Solderable iron wire according to Claim 1, characterised in that the interpenetration barrier layer is a copper layer (2) and/or a nickel layer (3).

3. Solderable iron wire according to Claim 1 or 2, characterised in that the copper layer applied galvanically to the iron wire has a thickness of 0.5 to 4 , preferably 2 ,u.

4. Solderable iron wire according to Claim 1, 2 or 3, characterised in that the thickness of the nickel layer amounts to 0.5 to 4 ju, preferably 2 y.

5. Solderable iron wire according to one of Claims 1, 2, 3 or 4, characterised in that the thickness of the tin layer amounts to 3 to 10 , preferably 5 ,u.

6. Method for the production of a solderable iron wire according to one of Claims 1 to 5, characterised in that a copper layer (2) and/or nickel layer (3) is applied directly galvanically to the iron wire (1) and a tin layer (4) is applied, as known per se, upon this layer (3) or layer (2).

7. Method according to Claim 6, characterised in that the tin layer or tin-lead alloy layer is applied galvanically.

8. Method according to Claim 6, characterised in that the tin layer or tin-lead alloy layer is applied in a manner known per se by drawing of the wire through a tin bath or a bath with a solderable alloy.

9. A method for the production of a solderable iron wire substantially as hereinbefore described with reference to the accompanying drawings.

10. A solderable iron wire substantially as hereinbefore described with reference to, and as shown in, Figure 1 of the accompanying drawings.