DE3011821C2 - Method for soldering two metal parts - Google Patents

Description

25th

The invention relates to a method for soldering a metal part containing silver onto a Copper, a copper alloy or a further metal part made of copper or an alloy and steel.

The contact point or the contact points of an electrical switch must be made of a material that is both erosion-proof and weld-proof, so that, on the one hand, the KontaktmaterLI does not disappear too quickly and, on the other hand, in the event of an unfavorable switching sequence, the two contacts with all the contacts in it Associated disadvantages is prevented. For this reason, AgCdO or AgSnO or AgC, for example, are used as the contact piece material. In particular, the last-mentioned contact piece material, which consists of 95% SiI- * over and 5% graphite, is - as far as the weld resistance is concerned - very favorable, so that it is often used as a contact material.

All of these materials have the disadvantage that they can be combined with copper or with a copper alloy, from which in the * 5 generally the carrier for the contact pieces consists, cannot be soldered easily. Because of this, the contact piece is placed on copper Interposition of a silver layer or a layer of a silver-cadmium alloy by means of such a commercial silver hard solder (according to DIN 8513. with a composition of, for example, 40% Ag, 19% Cu. 21% Zn. 20% Cd) soldered on. In well-known The solder melts at a temperature of approx. 700 ° and connects the silver or silver-cadmium alloy layers with copper.

When applying contact pieces made of silver, therefore, as shown above, a relatively large Amount of silver to be used. However, silver is an expensive material, so the object of the invention is to provide a w To improve the method of the type mentioned to the effect that the amount of silver to be used is significantly reduced.

According to the invention, this object is achieved in that, after the two metal parts have been cleaned, a layer made of AgP and AgCd is inserted and then melted at soldering temperature.

The method is carried out in detail as follows.

that the materials to be soldered together, for example the copper contact carrier and the made of silver-cadmium oxide contact piece, first cleaned by means of a flux that then on one or the other of the two to be soldered *! Metal parts have a layer of a silver-cadmium alloy and another layer of a silver-phosphorus alloy is applied to both Layers melt at the soldering temperature and together form a silver-cadmium-phosphorus eutectic. With this procedure, the layer required in the known processes can be silver or Silver-cadmium alloy can be omitted, which enables a saving of around 30% on silver will.

There is the option to do so instead of both Layers of AgP and AgCd form a uniform, through prior melting of the two .. materials to apply or use generated layer, so that it is no longer necessary to have two layers to be provided.

The following contact piece materials can be optimally connected to the copper contact carrier AgCdO. AgZnO, AgSnO, AgC In particular the AgC (»silver graphite«) is very difficult to use on copper to be soldered, since this material, which has a structure similar to gray cast iron when broken, is extremely weld-proof, however, it is not quite as resistant to erosion as other materials, from a normal hard solder such as AgCd or silver alone is only poorly wetted, which results in a relatively poor degree of filling If the latter Material applied to a copper contact carrier by means of the method according to the invention is, then this material can also be used and used optimally with a good filling level. Of the The particular advantage of this soldering compound, which consists of the two solder materials, is that it is easy to wet is considerably higher than with conventional plumbing.

The invention is explained and described in more detail using an example:

It is necessary to apply a contact piece made of AgC to a contact piece carrier made of copper. For this purpose, both the contact piece and the contact piece carrier are by means of a commercially available, adapted flux according to DIN 8511. Sheet 1. cleaned Then preferably A plate made of AgP and a plate made of AgCd are applied to the copper contact piece carrier The AgC contact piece is then placed on the two platelets and, depending on the size of the Contact piece carrier or the contact piece for a certain time at soldering temperature, in particular at approx. 700 "heated until both platelets fuse together After cooling, an ACdP eutectic that is clearly visible in the microscope results Copper contact carrier and the contact piece on the AgC firmly connects to each other and thereby a good Has electrical conductivity.

The soldering material Agrd and AgP is usually in the form of a sheet or in the form of sheet metal delivered whereby it can already be pre-cut to the contact piece size.

Another simplification can be that before applying the two materials to the Contact piece carrier melts the AgP and AgCd and thereby forms an alloy of AdCdP, which after solidification to a soldering foil with a suitable

Foil thickness can be rolled out. Micrographs have shown that the degree of filling is good and that it is Inclusions between the individual surfaces can be practically avoided. In the same way you can make an AgCdP wire that is used for automatic Soldering can be used.

Instead of melting both materials, AgP and AgCd, and a soldering sheet or a soldering wire you can make a brazing sheet from both materials and combine them to make one practical one-piece sheet metal (a kind of "bimetallic sheet").

Claims (3)

Patent claims: 1. Method for soldering a metal part containing silver onto one made of copper, a copper alloy or another metal part made of copper or alloy and steel, characterized in that that after cleaning the two metal parts as soldering material between the two metal parts a layer of AgP and AgCd is inserted and then melted at the soldering temperature. 2. The method according to claim I _1, characterized in that the two layers of AgP and AgCd are uniformly rolled together to form a single push or are produced by melting. 3. Application of the method according to claims 1 or 2 for applying contact pieces from a silver alloy, in particular from AgCdO, AgZnO, AgSnO or AgC on a contact piece carrier made of a copper alloy, in particular made of copper or copper-containing steel.