DE2817673A1 - METHOD AND DEVICE FOR PRODUCING A CONTACT LAYER WELDED ON A METALLIC SUPPORT - Google Patents

Description

PATENT LAWYERS

O-1 BERLIN-DAHLEM 33 PODBIELSKIALLEE

.6- DB MUNICH 22 W1DENMAYERSTRASSE 49

BERLIN:

DIPL.-INQ. R. MÜLLER-BORNER

Battelle Memorial Institute MUNICH: DIPL.-INQ. HANS-HEINRICH WEY DIPL.-INS. EKKEHARD KORNER

Berlin, April 19, 1978

"Method and device for the production of a welded onto a metallic carrier Contact layer "

(corresponding to Switzerland No. 4879/77 of April 2, 1977)

29 pages of description with 14 claims 1 sheet of drawing

Se - 27 324

BERLIN: TELEPHONE (030) 8312088 CABLE: PROPINDUS TELEX 01 84057

, 809843/10 ^, 2

CHEN: TELEPHONE (O89) 22 55 85 CABLE: PROPINDUS TELEX 0524244

- sr-

The present invention relates generally to the manufacture of solid coatings on predetermined Areas of metallic organs, in particular the production of contact layers on electrical or mechanical Liaison bodies.

The known methods for applying 3 layers physically, chemically or electrolytically do not allow layers with one, more than a few tens of microns thick quickly and economically to deposit. The deposition of composite materials is also often difficult or even impossible with the help of these known deposition processes.

The well-known method of welding prefabricated and corresponding contact layers in the form of, for example, thin platelets, on the other hand, can be considered be drawn if the layers are thicker than 400 ^ um, however, the production and handling of the platelets is very difficult because their thickness is much less than this value. the Prefabrication and welding of contact plates with a thickness of 100 to 300 µm is actually difficult and is not suitable for mass production.

Industrially prefabricated contact layers have a thickness of over 400 μm and are thus clearly above the thickness which is often required so that they can perform their task satisfactorily, for example 100 to 20O ₇ AIm in the case of contact layers for various electrical connection elements.

80 98 43/1012

■ 2-

In the case of contact layers containing expensive metals such as silver, there is particular interest try to save on such materials by adding only the smallest exactly necessary to these layers Thickness there because the cost of materials is an important economic factor in industrial Can represent production of contact layers.

The present invention has the object of avoiding the disadvantages mentioned and in particular a simple, to enable reproducible and economical manufacture of contact layers that are in place be formed and fixed on the connecting members, according to any desired shape and with a relative small thickness, preferably between 50 and 300 ami lies.

To solve this problem, in a method for producing one of a at least partially metallic coating with a predetermined outline and predetermined thickness and formed on a metal support welded contact layer proposed according to the invention,

a) that a predetermined amount of an at least partially metallic powder that the manufacture allows the desired contact layer to be deposited on a predetermined area of the surface of the carrier,

b) that one arranges a dielectric insulating mask on this surface of the carrier, which with at least a passage is provided which enables the delimitation of the contact layer to be produced,

809843/1012

c) that the powder lying on the surface of the carrier in the passage of the insulating mask by a exposing a first electrode to exerted pressure, which on the one hand creates a compressed powder layer is formed, which corresponds in outline and thickness of the contact layer to be produced, and on the other hand good electrical contact between these ο it. volume Electrode, this compressed powder layer and a the predetermined area on the carrier surface is created, and

d) that there is an electric current between the first electrode and one electrically connected to the carrier Opposite electrode can flow, so that this electric current the compressed powder layer flows through it and generates a sufficient amount of heat in it to heat it to such an extent that the temperature this layer reaches a sufficiently high value for its sintering and welding to de:; i predetermined Allow area without excessive heating of the support so that the desired Contact layer is produced by sintering and firmly welded to the carrier without the mechanical properties of this carrier experience a significant change.

Developments of this method according to the invention are given in the subclaims.

Furthermore, an apparatus is inventively used for carrying out the method according to the present invention. proposed according to which includes

- An insulating mask made of a dielectric material with a surface that supports the support of this Mask allows on the surface of the support, and

809843/1012

BAD ORiGINAL

• XO-

with at least one passage that allows cien to limit the desired outline of the contact layer to be produced,

- An electrical heating device with at least two electrodes, of which the first electrode is movable and has a cross section which is adapted to that of the passage of the insulating mask, so that this first Electrode can move along this passage in order to compress a powder and at the same time a good electrical contact between this first electrode, the powder compressed in this way and the surface of the carrier, while the second electrode forms a counter electrode that forms a circuit can build up the passage of an electrical current that can be regulated between these two electrodes through the compressed powder and through the area below the surface of the carrier enables.

The method which is the subject of the invention is well suited for deposition, sintering and welding of powders, especially for powder mixtures, their for the most part consists of a metal that, like silver, is commonly used in the manufacture of electrical contact elements used.

So allows the use of a mixture of powders, in particular to manufacture a sintered or welded coating made from a composite material consists, on the one hand a metallic matrix, for example made of silver, and on the other hand a dispersed one Has phase which is intended to give the desired coating special properties.

- 10 - 809843/1012.;,., £ ORDINAL

In particular, the use of silver enables excellent electrical conductivity to be ensured in two types of layers formed from a composite material:

- Self-lubricating contact layers from a composite Material that have a dispersed lubricating phase in a silver matrix and in particular the end. Graphite exist if the layer should have maximum electrical conductivity, or for example made of molybdenum bisulfide.

- Abrasion-resistant contact layers made from a composite material that has a dispersed phase in a Comprises silver matrix, which is intended to increase the frictional resistance of the layer, and for example is formed from tungsten carbide or aluminum carbide.

When using a mixture of powders to form one composed according to the present invention To produce material existing layer, this mixture generally contains on the one hand a metallic powder in sufficient quantity to produce a sintered metallic die to form the minimum Represents 80% by weight of the composite material from which the layer is made. This mixture contains on the other hand, another powder in sufficient quantity to form a dispersed phase that contains up to 20% and preferably contains 1 to 10% by weight of the material from which the layer is made.

The grain of the different in the powdery The powder used in the mixture is otherwise of almost the same size, and is preferably used in the

- 11 -

809843/1012 -

BATH ORIGINAL

Most of the cases powder of very fine grain size between 5 and 20 / in.

It is also important that the various used Powders are very intimately mixed with one another, so as to ensure their uniform distribution in the on the metallic Carrier to ensure deposited mixture and, as a result, satisfactory sintering and welding ensure that make it possible to produce a uniformly sintered layer that consists of a composite and material firmly attached to the carrier.

The powders or powder mixtures can advantageously be applied in the form of a paste-like color, specifically preferably using a Serxgraphietechnxk so that a layer with a relatively large thickness can impress. As a result, the screen normally used for screen printing is replaced here by a Replaced sieve plate, which has a hole corresponding to the circumference of each contact layer to be produced and, for example a thickness of 2 to 2.5 times greater than the final desired thickness of the sintered contact layer has what will generally be a layer of between 50 and 300 µm.

A layer is pressed through this sieve plate, the thickness of which depends on the one hand on the viscosity of the used Color depends, on the other hand, on the thickness of this sheet, which is also the maximum thickness of the printed layer certainly.

- 12 -

809843/1012

The ink used must be adapted to the implementation of the invention in each case SeXn ₁ so that its viscosity is high enough, for example of the order of 200,000 cp, so that it does not leak and so that it enables a clean print on the Manufacture carrier.

This color contains either the powder or the Mixture of powders, which is used to later produce the desired contact layer by sintering. on the other hand this paint comprises an organic binder which is intended to give it the desired viscosity, as well as a Solvent for the organic binder, which is also used as a dispersing liquid to implement the Powder or the mixture of powders in suspension.

The composition of this color should be chosen as follows:

- The solvent contained therein should not be volatile or be very little volatile at ambient temperature in order to avoid premature drying,

- in the case of drying carried out after printing, the solvent can evaporate without difficulty and that Binder can be decomposed into volatile products without leaving a substantial carbon residue, which inhibit the sintering or the desired properties of the sintered layer, for example its electrical conductivity, can significantly affect.

The colors available on the market, which would allow a satisfactory print to be made,

- 13 809843/101 2

817673

often do not fill the conditions required for the practice of the present invention, either because of their too high specific power resistance, be it because they require boiling temperatures that are too high.

Indeed, it has been found necessary to make special colors, all of which are required Meet conditions and in particular have the following properties:

- increased viscosity, which can be of the order of 200,000 cp,

- pseudo-plastic property of Pastej

- absence of excessive "sticking" of the paint on the screen plate used for printing;

- Possibility of slow drying of the paint very gradual removal of their liquid phase;

- Decomposition of the binder at a relatively low, preferably below 200 C temperature (which avoids annealing of a copper substrate can) leaving a solid residue, preferably less than 5% by weight of the organic binder,

- good adhesion to a copper carrier.

It is advantageous to use water as the solvent in order to facilitate the implementation of the invention and to also to avoid any unnecessary pollution. As a result, a water-soluble one is used in this case organic binder that can decompose at low temperature.

Because of the solubility and the thermal decomposition stress, one can advantageously use a binder

- 14 -

809843/1012

- 45

neither cellulose ethyl nor a polyvinyl alcohol use (for example "POLYOX" from UNION CARBIDK or "ELVANOL" from DUPONT DE NEMOURS or also "RHODOVIOL" by RHONE-POULENC).

The paint used to carry out the invention is prepared by mixing the powder with an amount of a binder-solvent solution so that the viscosity of the paint is correct.

The volumetric ratio of the powder to the solution in the color used is advantageously around 1: 1.

The organs that are to serve as supports for the pressure can easily be placed on one with suitable adjustment wedges provided plate are attached. After degreasing, these organ supports are tight with their outside Brought into contact with the perforated printing plate in order to avoid burrs and to bring the color in evenly to be able to distribute each hole of this pressure plate.

For example, a commercial machine allows printing to 200 to 300 each time it prints

2 organs with a surface area of about 30 cm. the The duration of this process is then in the order of magnitude of one minute for the setting of the organ supports supporting plate, the pressure and lifting of this plate.

- 15 -

809843/1012

ΕΛΒ ORIGINAL

- From

After printing, the ink is preferably dried slowly at a relatively low temperature in order to gradually ^{evaporate the solvent, for example at a temperature of about 60 °} C. in the case of an aqueous solvent. The organic binder can then be decomposed either by prior heating or during the sintering process.

It goes without saying, however, that the powder can also be applied to the organ support in any other suitable manner can be, as is described below by way of example.

After 'the powder has been applied to the metal support, according to the present invention, it is fried by using a dielectric insulating mask and welded, which is provided with at least one suitable passage, in which one localized one Heating by the Joule effect in a compressed powder layer, the circumference and thickness of which is in this passage can be restricted with the aid of a movable electrode.

A movable electrode adapted to the passage of the insulating mask allows a suitable pressure in the On the order of tens of kg / cm to exert the thickness of the compressed powder layer exactly to a certain value and a good electrical contact across it to create a compressed layer of powder through it.

- 16 -

809843/101 2

Thanks to this good electrical contact, the compressed powder layer makes it possible to create a suitable one Conducting an electric current, the intensity and duration of which can be precisely regulated, around this compressed powder layer subject to localized and well-controlled heating. This allows the temperature to increase this layer to a value just sufficient for the sintering of this powder layer and their welding on the underlying surface of the metal support without significant change in the Properties of this latter allow.

Indeed, due to the fact that the compressed powder layer consists of a multitude of granules is composed, its electrical resistance is significantly higher than the free resistance of the in it contained metal, so that the localized heating as a result of their increased resistance essentially takes place within this layer instead of in the electrodes and the metal carrier underneath.

As a result, the use of an insulating mask with a suitable passage allows, on the one hand, the electrical Pass current so that you can get warming through Can cause and control the Joule effect within the compressed powder layer very precisely. on the other hand the exact desired contour of the powder layer to be sintered can easily be predetermined by the mask provides a passage, the contour of which corresponds to this desired contour of the sintered layer.

- 17 -

809843/1012

The exact amount of powder required to produce the desired sintered coating can be based on deposited on the surface of the metal support in any suitable manner, whether by prior printing in the manner described above, be it by introducing this powder directly into the passage of the insulating mask, after the latter has been ordered on the parent company.

The powder used to produce the sintered coating can also either be in the passage of the insulating mask or be compressed outside of this mask beforehand. In this case, the movable electrode is used in addition, a reduced pressure on the so compressed Exercise powder to ensure the required shape and thickness and at the same time a satisfactory make electrical contact.

In practicing the present invention, it is advisable to meet the following conditions as much as possible to note:

- The powder subjected to sintering must be used for welding on the underlying metal surface of the parent company.

- The temperature reached during sintering and welding must be below the melting point of the metal support and of the metal to be sintered.

The essential electrical resistance on the path of the electrical current must lie in the compressed powder layer, which is subjected to sintering, so that any excessive heating of the metal support is avoided .

- 18 -

809843/101 2

-A-

- The duration of sintering and welding must be reduced as much as possible, to avoid any excess Heating of the wearer, the insulating mask and the Avoid electrodes.

It is generally possible to meet the aforementioned conditions Adhere to without major difficulty because they are for the majority of the implementation of the present The invention does not impose very substantial restrictions on the applications in question.

The process which is the subject of the present invention offers the following significant advantages:

- The substantially simultaneous sintering and welding make it possible, starting from different Powders to obtain layers sintered in place of small thickness, between about 100 and 200 / µm and which are difficult to realize by the aforementioned conventional methods.

- The heating localized in the passage of the mentioned mask supplies the mass to be sintered with the amount of heat, which is just sufficient to bring it quickly to the sintering temperature; this allows on the one hand a significant saving in energy and investment costs compared to heating in a sintering furnace and on the other hand, avoiding undesirable changes in the properties of the wearer as a result of one more or less long thermal treatment at high temperature during sintering.

- The production is much simplified and takes place takes place in a reproducible way with a minimum of expenditure of time thanks to the well-controlled sintering, which one in the mask at the same time as the weld

- 19 809843/1012

performs. In this way the number is reduced of manufacturing operations to an absolute minimum by keeping the pretreatment operations as far as possible turns off.

- The welding of the sintered layer in place and in the stud allows an optimal fastening to be guaranteed on practically the entire surface thanks to the numerous close contact points of the particles of the compressed Powder that is sintered on the surface of the metal support. On the other hand, the electrical Welding of a previously sintered solid plate generally only takes place at certain points, where the uneven surface of the rigid platelet is in electrical contact with the surface of the support comes, whereby the weld is then obtained on a more limited surface of the plate.

The following examples serve to explain the present invention with the aid of the accompanying drawings.

Fig. 1 is a schematic representation of the main parts of an apparatus for the production of contact layers in vertical section corresponding to the plane I - I of Figure 2.

Fig. 2 shows a plan view of a connecting member, which according to the invention with the aid of the device of Fig. 1 produced contact layers is provided.

example 1

Four contact layers la to Id (Fig. 2) made of silver-graphite with a thickness of 200 μm and a surface of 6 χ 4 mm are produced on an organ support 2 made of copper with a thickness of 2 mm , the total of which is

- 20 - 809843/101 2

dimensions are 80 χ 25 mm. Fig. 2 shows the relative Arrangement of the contact layers la to Id on this carrier 2, which in the present case is an electrical Liaison body is.

A mixture containing fine silver and graphite powder with an increased viscosity of 200,000 cp is previously prepared with the following volumetric composition:

- silver powder (cutting diameter less than 10 / um,

3 'gross weight 1.8 / cm,

specific surface 2 m / g, manufacturer DEGUSSA) 41 %

- graphite powder (cutting diameter less than 20 μm,

Manufacturer LE CAIlBONE LORRAINE) 9 %

- organic binder: polyvinyl alcohol (brand

¹¹ ELVANOL ", manufacturer DUPONT DE NEMOURS) 5 %

- Solvent: water 45 %

A predetermined amount of this mixture is then applied to each of the areas of the support 2, which is one of the to be produced contact layers la to Id should receive (see Fig. 2).

This deposit is made by serigraphic printing in this case with the help of a metal sieve plate with a thickness of 700 µm, having four holes forming 6x4 mm passages, the outline of which and relative arrangement of those of the contact areas la to Id which are shown in FIG.

- 21 -

809843/1012

The sieve plate is then like a serigraphic screen used to get four printed areas, each made up of a layer of the mixture, one of the areas la to Id corresponding to FIG. 2 cover and 50 mg of silver graphite in each printed .: area included.

The one printed in this way with these four «* λ areas provided carrier 2 is then gradually heated up to 200 C in such a way that the solvent evaporates and the binder disintegrates, both of which are contained in the mixture forming the printed areas.

This drying process enables four printed areas in the form of a powdery, dry deposit with a thickness of about 45 · ") a:;: i zu ernai.t-G ::, which is essentially made uniform with the graphite powder mixed silver powder and adheres to the areas of FIG. 2 designated by la to Id.

An electrically insulating mask 3 (Fig. Dvirä then on the surface of the carrier 2 arranged, this mask in the present case made of a perforated Ceramic plate is made of aluminum oxide and has four passages 4a to 4d that exactly match the contour and the correspond to the relative arrangement of the contact areas la to Id to be produced on the carrier 2.

As shown in Fig. 1, this insulating mask covers most of the substrate 2, with the exception of the areas la to Id, where the printed deposits, formed from drying powder adhering to the substrate 2, in

- 22 -

809843/1012

the corresponding passages 4a to <ftd of this mask are appropriate.

This insulating mask 3 is used to produce the desired contact layers la to Id on the dome carrier namely inside the corresponding passages 4a to 4d of this mask. The lower face of this mask is then kept in close contact with the upper surface of the carrier 2.

The four contact layers la to Id become simultaneously and made in the same way, each time with the aid of respective movable electrodes 7a to 7d.

For example, the movable electrode 7c- is used for Production of the contact layer la and has a shoulder 8a, which is on the outer surface the insulating mask 3 is placed and thus enables the determination of the desired thickness of the layer la to be produced, in the present case 200 Aim if this electrode 7a is inserted into the corresponding passage 4a and its shoulder 8a rests against the surface of the insulating mask 3.

The cross section of the movable electrode 7a corresponds to de.n of the passage 4a, so that this electrode has a sliding piston forms with little play along this corresponding passage.

The deposition of dry powder previously printed on the area la and deposited in the passage 4a is entered in this way by the electrode 7a.

- 23 -

809843/1012 BaDo?

8 * 17673

closed and compressed to form a compressed layer of powder that has the desired outline and has the desired thickness when the shoulder 8 a rests against the insulating mask 3.

The pressure exerted by the movable electrode is used, on the one hand, to determine the shape and the exact shape Dimensions of the layer to be produced and on the other hand to produce a good electrical contact between the movable electrode 7a, the compressed powder layer and the underlying area of the surface of the carrier 2.

The pressure applied by the movable electrode is in the present case of the order of 10 kg / cm

Furthermore, a counter electrode 10a with good electrical contact is on the opposite surface of the carrier 2 with respect to the passage 4a, with the electrodes 7a and 10a connected to the opposite terminals a (not shown) electrical power source with adjustable strength are connected.

When the movable electrode 7a is pressed into the passage 4a up to its shoulder 8a and so at the end their compression path arrives (shown by dashed lines in Fig. 1), imagines electrical circuit between the power source, the electrode 7a, the compressed powder layer (silver-graphite), the carrier 2 and the electrode 10a.

- 24 -

809843/1012

. as · - <

The establishment of this electrical circuit is then used to carry out a sintering process, which one can control very precisely. This sintering takes place in the present case by applying a controllable Voltage below 5 V between electrodes 7a and 10a and by constantly passing an electrical current of approximately 5000 amps between and through them the compressed powder layer takes place in the passage 4a for 0.45 seconds.

This short run through the compressed powder layer creates a well-controlled heating of it Layer by Joule effect. This controlled heating is essentially localized in the passage 4a and therefore allows to deliver the amount of heat that for sintering the trapped in this passage, compressed powder layer and the welding of the sintered contact layer obtained in this way on the underlying surface of the carrier 2 is required.

Such a well-controlled current flow enables four contact layers la to Id to be produced at the same time, which are sintered and welded onto the carrier 2 without this carrier being noticeably heated. Indeed the temperature of the copper carrier 2 rises at most 60 to 80 C in the present case and thus remains well below the annealing temperature of the copper.

The mechanical properties of this copper carrier 2 therefore suffer due to localized heating in each of the connecting organ

-2S-

09843/1012

. afc

Passages 4a to 4d of the insulating mask 3, sintering and the welding, no significant change .

In the same way, the compressed one suffers Powder layer contained graphite no undesirable change due to this sintering and Welding process.

In the present case, the electrodes 7a and 10a are made of tungsten on the one hand because of its good conductive properties, which make it possible to ^{see the entire ohm 1} voltage drop and consequently to reduce the energy consumption during sintering, and on the other hand because of the reduced risk of the electrodes sticking to the sintering powder and on the support during welding.

In a modification, electrodes made of graphite were used without any significant wear and tear on them Electrodes during sintering.

Example 2

Four contact layers la to Id are placed on one Carrier 2 according to the arrangement according to FIG. 2 and • the manner described in Example 1 above.

Its powdery, homogeneous mixture is starting out of a silver powder (cutting diameter below 20 / um) and a graphite powder (cutting diameter below 20 / am) produced, which are intimately mixed with one another in a weight ratio of 97 ί 3.

- 26 f
809843/1012

The one described in Example 1 and shown in FIG The insulating mask 3 is then, as already described above, brought into the required position on the carrier 2.

The amount of silver-graphite mixture is then passed into each of the passages 4a to 4d of the insulating mask 3 a, which is necessary for the production of one of the contact layers la to Id, i.e. 50 mg this mixture per layer in the present case, in such a way that the powdery mixture on the Area of the surface is deposited which lies under the carrier 2.

Then you take the compression and the sintering of these powdery mixture in the same way as described in Example 1 above.

In this case, the same sintered contact layers la to Id with a thickness of 200 μm are obtained which are firmly attached. the surface of the carrier 2 are welded.

Example 3

Put: an abrasion-resistant coating in the form of four contact layers, which correspond to the illustration in FIG. 2 and the description in Example 1 evenly on the areas la to id on one Copper carrier 2 are deposited.

This coating is produced from a powdery homogeneous mixture, which is by intimately mixing the type nickel powder

- 27 -

809843/1012.

MOND 255 (International Nickel Ltd.) with a middle Section of 5 µm with silicon carbide powder with a mean section of 20 µm in a weight ratio of 90:10 prepared.

This mixture: is then used to produce four contact _{layers Ia to Id 1} in the manner described in Example 2 with the aid of a device as shown in FIG. The sintering and welding of these contact layers then takes place in this case by continuously passing a current of 6000 amperes through the areas la to Id to be produced for 0.75 seconds.

Example 4

Four contact layers Ia to Id are made of silver-graphite forth, which are attached to a copper carrier 2 (Fig. 2).

For this purpose, a powdery, homogeneous mixture is made beforehand made of a silver powder (cutting diameter less than 20 μm) and a graphite powder (cutting diameter less than 50 μm) produced, which are intimately mixed in a weight ratio of 97: 3.

Then, flakes are made from pre-compressed powder, starting from the predetermined amount of this powdery Mixture of silver and graphite, which are required to produce each of the desired contact layers la to Id, d. H. 50 mg of this mixture.

For this purpose, 50 mg of this powdery mixture are introduced into a compression mold with a perforation, the outline of which

- 28 -

809843/1012

corresponds to that of the plate to be produced and which is slightly smaller (3.8 5.8 mm) than the one to be produced Contact layers la to id. This powdery mixture is then inserted into the perforation of the die in which it is pressed under a pressure of

2
about 200 to 300 kg / cm is compressed.

This is how you place each pre-compressed tile here, which is then ejected from the mold with the help of another piston and into one with the help of a suction pipette of the passages 4a to 4d of the insulating mask 3 (Fig. 1), which are used to produce the desired contact layers 4a to 4d is used, in a manner corresponding to the above-described Examples 1 and 2.

To produce the contact layer la in the present case, for example, the movable electrode 7a is pushed as far as it will go pressed in on the precompressed plate that was previously inserted into the passage 4a in order to be able to use this

2
Apply a pressure of 10 kg / cm to the platelet. In this way, an electrical circuit is set up in order to allow a current to flow through under the conditions described in Example 1 in order to sinter and weld the contact layer 1 a on the carrier 2.

Due to the pre-Kora compression carried out in this case of the platelets, it is not necessary to provide the movable electrode 7a with a shoulder like the shoulder 8a (FIG. 1) to be provided because the thickness is essentially due to the amount of the pre-compressed powder is determined.

It goes without saying that contact layers are produced on a large scale in accordance with the present invention can be, with many contact layers at the same time

- 29 809843/1012

can be produced on a common carrier or on different carriers lying next to one another.

Se / MP - 27 324

809843/101 2

Claims (14)

-X- Claims Method for producing at least one from an at least partially metallic coating with contact layer formed with a predetermined contour and predetermined thickness and welded onto a metal support, characterized, a) that a predetermined amount of an at least partially metallic powder that the manufacture allows the desired contact layer to be deposited on a predetermined area of the surface of the carrier, b) that a dielectric insulating mask is arranged on this surface of the carrier, which mask has at least one passage is provided, which enables the limitation of the contact layer to be produced, c) that one lying on the surface of the support powder in the passage of the insulating mask through a first Electrode is exposed to applied pressure, whereby on the one hand a compressed powder layer is formed, which in Corresponds to the outline and thickness of the contact layer to be produced, and on the other hand a good electrical contact between this first electrode, this compressed powder layer and the predetermined area on the Carrier surface is created, and d) that there is an electric current between the first electrode and one electrically connected to the carrier Can flow counter electrode, so that this electric current flows through the compressed powder layer and in you generate a sufficient amount of heat to keep you going 809843/1012 to heat that the temperature of this not reached a sufficiently high fourth to allow their sintering and welding on the predetermined Allow area without excessive heating of the support, so that the desired contact layer produced by sintering and firmly welded to the carrier without affecting the mechanical properties The wearer has experienced a significant change. 2. The method according to claim 1, characterized in that - That the powder is deposited by one of a pasty, in a liquid phase dispersed mixture of this powder existing layer prints, - that this printed layer is dried, - That one arranges the insulating mask on the surface of the support so that the printed and dried Layer lies in a corresponding passage of this mask, and - that this printed and dried layer is subjected to a pressure exerted by the first electrode exposes, so that the compressed powder layer is formed through which the electrical current is passed lets flow. 3. The method according to claim 2, characterized in that the pasty mixture has a viscosity on the order of 200,000 centipoise. 809843/1012 ^ - GRSSJMAL 4. The method according to claim 2 or 3, dadvirch characterized in that the liquid phase of the pasty mixture is an organic, in water Has dissolved binder. 5. The method according to claim 2, characterized in that the volumetric ratio between the liquid phase and the powder contained in the pasty mixture is in the order of 1: 1. 6. The method according to claim 4, characterized in that that the dissolved organic binder has a concentration between 5 and 20%, preferably between 8 and 12% by weight of the liquid phase. 7. The method according to claim 2, characterized in that the layer with the help of a screen with at least one opening whose cross-section corresponds to the desired outline and the thickness of which is greater than that of the contact layer to be produced. 8. The method according to claim 1, characterized in that the powder on the Carrier is deposited by placing it in the passage of the insulating mask that was previously placed on the carrier was ordered. 809843/101 2 9. The method according to claim 1, characterized in that that the powder is subjected to a preliminary compression before it is put on applies to the wearer. 10. The method according to claim 1 for producing a contact layer from a composite material, characterized in that the powder applied to the carrier consists of a uniform Mixture consists of at least two powders that form the desired contact layer from a composite material by sintering at least one of these two powders enable. 11. The method of claim 10 for producing a Contact layer made of a self-lubricating composite material, characterized in that that the mixture applied to the carrier is a metal powder that is used to form a sintered Die is used, and contains a non-metallic powder that is used to form a dispersion phase in this die and to impart self-lubricating properties to the composite material. 12. The method according to claim 11, characterized in that the on the carrier Applied mixture consists predominantly of silver powder and contains graphite powder, which is the composite Material that gives self-lubricating properties. 809843/1012 13, method according to claim 12, characterized in, <leave them on the carrier Applied mixture contains between 1 and 10% by weight of graphite. 14. Apparatus for performing the method according to claim 1, characterized by - An insulating mask (3) made of a dielectric material with a surface. That supports the support this mask allows on the surface of the carrier (2), and with at least one passage (4a to 4d), which enables the desired outline of the contact layer to be produced (la to ld) to limit, - An electrical heating device with at least two electrodes (7a to 7d, 10a to 10d), of which the first electrode (7a to 10d) is movable and has a cross section that corresponds to that of the passage the insulating mask is adapted so that these first electrodes move along this passage can to compress a powder in it and at the same time make good electrical contact between this first electrode, the powder compressed in this way and the surface of the support create, while the second electrode (10a to 1Od) forms a counter electrode that forms a circuit can build up the passage of a controllable electrical between these two electrodes Flow through the compressed powder and through that lying below the surface of the carrier Area allows. Se / MP - 27 324 - 6 - 8Q9843 / 1012