DE1923352A1 - Method for producing a contact element with a gold contact - Google Patents

Description

The invention relates to a method for producing a Contacts for connecting elements, snap switches and the like.

In the past, spring elements were used for sonic switches and the like made of copper, which are special as contacts Exhibited areas. It was later found out that one could decrease the contact area and increase the contact pressure could without affecting the electrical function of the switch. This development made possible building smaller switches at lower costs but increased oxidation of the contact surfaces with itself. Because copper oxide has a high resistance in relation to pure copper possessed, two problems arose in the formation of oxides

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on: firstly, the electrical properties of the switch deteriorated significantly, and secondly, it led the higher resistance to increased heat development and ultimately to damage to the contact. To the Formation of copper oxides and their disadvantageous side effects to avoid, it has been proposed to use a material to produce the contacts, its Oxides have only low electrical resistance, or metal such as silver, whose oxides physically and are chemically unstable and either disintegrate or under normal conditions of use easily rub off the switch and at the same time offer low electrical resistance.

The first attempt was made to solve the oxidation problem by making the contacts from pieces of platinum or silver to get hold of which were riveted. The use of rivets is of course extremely costly, since only a small one Part of the rivet surface serves as the actual contact. This problem has been solved in part by using the Rivet made from another metal, e.g. from copper and then a thin layer of platinum or silver on the contact area by welding or soft or hard soldering applied. Unfortunately, with the riveting process, especially in series production, one often only obtains very poor mechanical and electrical connections, and at the junction with the actual contact results in an area with uneven metal corrosion.

Several methods of making contacts have also been developed, known as "insert methods" could denote. According to this method, an undercut slot was formed in the contact element, in which a cadmium piece was used. This use- "

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form turned out to be very useful for prevention from sparkover, but rejected most of the physical and electrical disadvantages with which the riveting process was afflicted. According to Another known process (U.S. Patent No. 2,137,617 issued November 22, 1938) was incorporated into a Corrugated or recessed area silver melted, which is an advance over the cadmium method depicted.

In addition, some electroplating techniques have also been developed and methods of spraying the precious metal onto the contact area. These procedures have the disadvantage that they give a granular coating which has poor electrical properties and has only low corrosion resistance.

Further methods for soldering that have been known for a long time of the precious metal on the contact element required high temperatures, with the contact carrier being annealed and lost its elasticity.

According to the most famous method of making a Contact was a piece of precious metal on a spring element ^ welded at the desired point. Often the contact carrier consisted of relatively thin The material and the intended contact surfaces were extremely tiny. This welding process became costly Precious metal melted and lost; it also required a second work step to make the contact shaped accordingly so that the oxide could be easily removed, and it often became the thin one Carrier material burned out.

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According to a more recent method, a globule is produced with a diameter of 26 mil - (approx. 0.6 mm) used. This Egg is first on the contact carrier in the Positioned in the correct position, then welded on and finally shaped, usually by embossing. Dias has however, it turned out to be a rather expensive procedure, since a relatively large amount of gold must be used.

The method according to the invention eliminates all of the above Disadvantages and allows the worker to get the required Precise determination of the amount of precious metal in advance, using as simple mechanical means as possible is intended for the formation of the Eontaktform.

According to the invention are relatively thin, small Chips made of precious metal are welded out onto a relatively wide support surface.

Next, close to the method according to the invention, the noble metal is on the Eontaktträger surface before training of the contact element applied.

In addition, a ^ JK contact element is used according to the invention with eontaktejo molded in a two-part die. made of precious metal.

In the following the invention with reference to the enclosed Drawing explained in more detail:

In the drawing shows: .. - ■ -; ■ - '· .. ■ - ■;, -

Pig. 1 is a top view of ^ # ^

f it, being the Eontm ^ t ^ emea ^ b and the Contact areas indicated / 1212

Pig. 2 is a plan view of a portion of the

Carrier strip, with the direction of movement of the gold foil and its ratio is shown to the carrier?

Pig. 3 shows a section along the line 3-3 i

Pig. 2, showing the initial tack weld}

Pig. 4- a section after Pig. 3 »after Shear j

Pig. 5 a side view of the carrier with the gold chip welded on}

Pig. Figure 6 is a side view of the one welded to the beam Spans after deformation}

Pig. 7 is a side view of the finished contact. elements.

A gold foil 1 mil (about 0.025 mm) thick and 40 mil (about 1 mm) slurry is produced in accordance with the method of the present invention te on a support made of phosphor bronze or other electrically conductive material. The metal of the The contact carrier must also be elastic and be able to accommodate lines from a wire winding machine.

The process begins with cleaning and tinning the flat support surface. If desired, wire can also be used can be used as a carrier. The carrier material is in Porm one. 5 cm wide and 12 mil (approx. 0.3mm) thickness provided. The carrier strip is through

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Hot-dip tinning or tin-plated by other processes in order to obtain corrosion resistance and to simplify the soldering of conductor connections. A row is then made in the carrier strip . punched from reference holes as shown in FIG. The pre-punched holes make it possible to easily position the strip in the welding head and also in the punch used to form the contact element. ; , In addition to the holes, other position reference symbols can also be used. As soon as the carrier strip has been brought into the correct position, the gold foil is fed in parallel to it in the same feed direction as the carrier strip, so that the carrier strip is in! superimposed on the contact surface and, as shown in Fig. 2,

erf at an angle of 45 ° to the later contact finger stretches. The gold foil is attached to the carrier strip at its front edge to secure the at the same time chip-like gold flakes resulting from shearing to the desired length. If necessary the gold foil can of course also be fed at an angle to the carrier strip. With the help of the pre-punched holes brings the welding head in the chip-like gold flake; a second welding position in which it is connected to the carrier strip surface is welded. The still strip-shaped contact carrier with the welded gold leaf is, as shown in Fig. 5, inserted into a two-part die, in which the contact surface through Embossing is deformed raised (Fig. 6), so that the part covered by the gold leaf bulges outwards. The contact strip is then a punch with automatic Feed fed and formed by a known tech African method into a contact element shown in FIG.

Patent attorney Dipl.-Ing E. Eder

■ Og UEUMtatnB · 34

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Claims (1)

Patent attorney MOnchm 13, Ellwbethttr. 34 Godfather in t a ns ρ r ü cn e Method for creating a contact element, marked by arranging a strip of gold foil parallel to a carrier, fastening the front edge of the gold foil strip on the carrier, shearing .des gold foil strip ens in a predetermined Distance to its leading edge so that a kind of chip arises, by attaching the remaining chip portion to the carrier and by deforming the carrier and the associated chip into a raised contact and through subsequent training of the rest ■ * '-.- ■' - ■ »· ·. ■ ■. "■■ -. Contact element. 2 · The method according to claim 1, characterized in that the raised deformation of the carrier and the Spans is done by a Pxäge process. 5, method according to claim 2, characterized in, that the width of the carrier exceeds that of the gold foil many times over. 4 ·. * Method according to claim 5 »characterized in that that the carrier is strip-shaped and with a position mark before attaching the gold foil is provided. 5 «Process for the production of a contact element, marked dunh tinning of a flat, strip * Fen-shaped carrier material, punching out a row of reference holes from the carrier material, through pa- 9t3 9 8 5 1/1 212 -V- parallel arrangement of a gold foil strip to the carrier material, attachment of the gate edge of the gold foil strip to the carrier, protection of the gold foil strip so that a kind of chip is disfigured, by fastening the remaining chip portion on the carrier, arching deformation of the carrier material at the point covered by the chip and through subsequent shaping of the remaining contact element. ORIGINAL INSPECTED 9 0 38 5 1 / '2' I. "