LU502912B1 - Method for depositing a metallic material on a ceramic or mineral substrate using an application device - Google Patents

Abstract

The invention relates to methods for depositing a metallic material (14) on a ceramic or mineral substrate (6) using an application device (1). A high-energy beam is directed onto a surface (5) of the ceramic or mineral substrate (6) from an energy source (2) arranged on the application device (1). The metallic material (14) is applied to an area of the surface (5) of the ceramic or mineral substrate (6) using the application device (1). The metallic material (14) is at least partially melted using the high-energy beam, so that after the metallic material (14) has solidified, the metallic material (14) is deposited as a material deposit on the surface (5) of the ceramic or mineral substrate (6). The high-energy beam striking the surface (5) of the ceramic or mineral substrate (6) defines a working area (7), wherein the position of the working area (7) on the surface (5) can be changed by a relative displacement of the surface (5) of the ceramic or mineral substrate (6) and the laser device (3). A depression (13) is made in the working area (7) on the surface (5) of the ceramic or mineral substrate (6), wherein the material is applied into the depression (13).

Description

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LU502912

Ponticon GmbH

Process for depositing a metallic material on a ceramic or mineral substrate with a

Application device

The invention relates to a method for depositing a metallic material on a ceramic or mineral substrate using an application device, wherein a coating layer arranged on the application device

Energy source a high-energy beam on a

Surface of the ceramic or mineral substrate, wherein with the aid of the application device the metallic material is applied to an area of the surface of the ceramic or mineral substrate, wherein the metallic material is at least partially melted with the high-energy beam, so that after the metallic material has solidified the metallic material is deposited as a material deposit on the surface of the ceramic or mineral substrate, wherein the high-energy beam impinging on the surface of the ceramic or mineral substrate defines a working area, wherein the position of the

Working area on the surface by a relative

Displacement of the surface of the ceramic or mineral

substrate and the energy source can be changed.

For depositing or applying a metallic material onto the surface of a metal substrate, the

Laser deposition welding for machining workpieces

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LU502912 established procedure. In the conventionally performed

The method involves using an application device with a

Laser equipment is used. The surface of the

Metal substrate is melted locally at the point of impact by a laser beam emitted by the laser device and directed at the surface. A fine-grained metallic material is fed into the local melt thus created. The feed takes place by transport using an inert carrier gas. The metal powder fed into the local melt in this way is also melted by the laser beam or the heat of the existing melt of the substrate. After the molten metallic material has solidified, a material bond is formed between the metallic material and the metal substrate. This process can be carried out by a

Relative movement of the metal substrate and/or the

Application device at various points of the

metal substrate repeatedly or over a continuous area of the surface.

However, this conventional method has disadvantages in the

Application of a metallic material to a non-metallic substrate such as a ceramic substrate or a mineral substrate. Due to the different chemical and physical properties inherent in the material classes, it is challenging to create a bond between metal and ceramic using a laser beam, for example. Due to the generally high melting points of ceramics, which can be in a range between 2000 and 3000 °C, melting is complex, especially since the required temperatures are sometimes above the boiling point of the metallic materials used.

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LU502912

materials. Thus, no material application would be possible due to the evaporation of the applied metallic material. Furthermore, ceramics and metallic

Materials have different expansion coefficients, which are in the range of 4 to 13 10-6K-} for ceramics and between 1 and 30 106K! for metallic materials.

This results in heating by the

Brittle fracture tendency of ceramics the problem of cracks and

Fracture in the ceramic substrate, especially during rapid heating and cooling processes, such as those

use of laser radiation. Due to the large and rapid induced heat and the low

Thermal conductivity of the ceramic creates tensions in the

Ceramics. Since ceramics have very little deformability even at higher temperatures, it is difficult to reduce these thermal stresses, unlike metallic materials. If these stresses exceed the

If the material hardness is too high, they lead to fracture. These effects lead to the failure of the component and are irreparable. Another problem is the poor wettability of the ceramic with molten metals due to the so-called "Balling Effect™".

Various methods are known from the state of the art to overcome the problems mentioned. On the one hand, the application of physical vapour

Deposition (PVD) is the most commonly used method.

An active metal such as a metal alloy or a

Pure metal is transferred into the gas phase and then used as

Bonding agents are deposited on the ceramic surface, creating a thin metal layer.

Thin metal layer acting as an adhesion promoter can be

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LU502912

The actual metallic material is then applied. This process takes place under vacuum or inert gas conditions. Furthermore, the

Surface of the ceramic substrate elaborately before

The metal must be cleaned before application in order to enable a suitable bond to the ceramic substrate. Metallization using PVD processes is subject to cleaning of the

Surface other limiting factors. For example, the size of the substrate to be coated is also dependent on the

Size of the available process chamber.

Another well-known method is aerosol jet printing (AJP). The metallic material is applied as an aerosol. The aerosol is generated in an ultrasonic or pneumatic atomizer and applied to the substrate together with a carrier gas at high pressure. The disadvantage here is that only layers in the micrometer range can be applied and layer thicknesses in the millimeter range cannot yet be produced.

It is therefore considered to be the object of the present invention to offer an alternative to the methods known from the prior art, which can offer significant economic and technical advantages.

The task is solved by applying in the working area on the surface of the ceramic or mineral

A depression is made in the substrate, whereby the

Material is applied into the recess.

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LU502912

By applying the metallic material to the

Indentation can ensure reliable adhesion of the metallic

The method according to the invention advantageously allows a geometrical freedom, which also allows 3D geometries to be coated. In addition, isolated, individual areas can be coated selectively without the need for masking or other preparatory work, as is the case with the methods from the prior art.

The process also makes it possible to produce a firmly adhering, electrically conductive metal coating without additional flux and at high application rates on ceramic or mineral substrates.

Unlike processes such as PVD, no

A process chamber that can be flooded with protective gas or an evacuatable process chamber is required. Application areas can include implants in medical technology as well as components in the automotive sector and in aerospace.

Circuit boards for high-performance LED

installations. The process can also be used in the production and development of

Energy storage can be used.

The metallic material melted by the high-energy radiation can be fed in liquid form into the

Deepening of the surface of the ceramic or mineral

Substrate, whereby after solidification it is mechanically clamped to the wall areas and the

bottom area of the depression and adheres there.

This allows the adhesion of the metallic material to the ceramic or mineral substrate in contrast to the direct application of the metallic material to a

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LU502912 planar surface can be significantly improved and increased.

The recess also allows a stable, material-locking connection of the metallic material to the ceramic or mineral substrate through

diffusion processes and ultimately by reactions at the atomic level - which lead to bonds.

It is possible that the metallic material in

Based on the classic laser deposition welding, the coating can be applied as a fine-grained powder, or the coating can be applied as a powder fed via the application device or in the

A wire arranged in a recess is used, which is melted by the introduced energy.

A ceramic substrate is understood to be a substrate made of a ceramic material. Fin ceramic

Material is a material which is synthesized from non-metallic inorganic substances at elevated temperatures and thereby acquires its characteristic properties such as its high melting point, its low electrical

conductivity as well as its brittleness. These include, for example, oxides, nitrides or silicates.

Furthermore, in this sense, glass ceramics that have an amorphous phase in addition to a polycrystalline phase are also considered ceramics in the broadest sense.

In addition, glasses can also be used.

Under a mineral substrate, geological

Processes generally refer to crystalline substances of very different chemical composition, such as granite.

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In an advantageous embodiment of the invention, it is provided that the energy source is a laser device emitting a laser beam, wherein the surface is selectively removed by the laser beam directed onto the surface, so that the removed material

A depression is created on the surface. The use of a

Laser beam is a cost-effective and effective way to create a recess in the surface of the ceramic or mineral substrate.

Laser devices can be particularly high-performance laser devices such as solid-state lasers - including

Diodes or fiber lasers - but also classic CO2 lasers for

Due to the high performance of the

Laser radiation hitting the surface can cause individual

Layers or particles are dissolved from the surface and selectively removed. The removal can

Depending on the specific performance as well as the cross-section of the

Laser radiation can create the desired geometric shape of the

Deepening can be controlled. The removal and thus the

Removing heated material from the ceramic or mineral substrate also prevents heat-induced stresses that could transfer to the ceramic or mineral substrate and damage it.

Due to the relative movement of the ceramic or mineral

Substrate and the application device, the depression can be placed at different locations on the ceramic or mineral

substrate repeatedly or over a continuous

area of the surface. In this way, trench or furrow-like structures as well as any

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LU502912 other geometric structure can be created on the surface of the ceramic or mineral substrate.

In addition to the use of a laser device, the

Energy source also an electron beam emitting

This can be particularly useful if

It can be advantageous if the metallic material is introduced into the recess as a wire, for example, and

energy source such as an electron beam.

According to an advantageous implementation of the inventive concept, it is provided that the depression made in the surface of the ceramic or mineral substrate is a V-shaped depression with an acute angle. Preferably, the depression has a V-shaped geometry so that the melted metallic material can easily flow into the depression. After solidification, the metallic material can be flush with the surface so that a depression with a triangular cross section is created. In an alternative embodiment, the metallic

Material can also form a raised area on the surface, resulting in an essentially "cake-shaped" cross-section. In addition, the metallic material can only partially fill the depression after solidification.

In addition to a V-shaped depression, the depression can also have designs that deviate from a V-shape, in particular a U-shape. Furthermore, designs of the depression with a rectangular, trapezoidal or other

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LU502912 polygonal cross-section according to the invention. The recess can also have undercuts.

The recess mentioned above allows the molten metallic material to flow into the

deepening and at the same time optimized wetting of the

Surface through the metallic material.

Advantageously, the invention provides that the metallic material introduced into the recess and melted has a contact angle © < 90°.

The contact angle is the angle that a drop of liquid on the surface of a solid forms with respect to this surface. This angle can be determined by the

Young’s equation. In the present

In this case, the metallic material applied and melted onto the surface of the ceramic or mineral substrate can be considered as a liquid and the ceramic or mineral substrate as a solid.

The size of the contact angle between the liquid and the

Solid is a function of, among others, the

Interaction between the two phases at their

Contact surface. The wetting of the surface by the liquid drop can be determined depending on the

Cohesive forces within the drop and the

Adhesion forces of the liquid drop against the

surface. If the cohesive forces within the liquid drop exceed the adhesive forces between the liquid drop and the surface, the liquid drop will take the shape of a sphere and the

Only touch the surface on a small contact area.

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LU502912

In the case of a liquid metal on a ceramic or mineral substrate surface, the

Cohesive forces far exceed adhesive forces, so that on a planar surface a sphere with a

Contact angle © > 90°. The following applies: The smaller the

The higher the contact angle, the larger the contact area.

In order to enable the best possible bonding and thus the largest possible contact surface of the liquid droplet to the ceramic or mineral substrate, the contact angle 6 should preferably be > 90°.

The depression forms a geometric shape on the

Surface of the substrate. The inventive

Designing this recess with, for example, a V-shaped design with an acute angle, the

The contact angle of the metallic material flowing into the cavity or melting there is reduced to below 90°, which optimizes the wettability of the cavity surface. Thus, by artificially reducing the contact angle through the geometric design of the

Deepening an optimal connection of the metallic

material to the ceramic or mineral substrate. As already mentioned, the recess can also have other designs other than a V-shape, as long as the selected design creates a suitable angle between the opposing surfaces in an upper area of the groove.

The low contact angle and thus the largest possible bond between the two phases remains even after

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LU502912 the hardening of the metallic material, which ensures a continuous connection without bubbles or

cavities can be reached.

It is also possible and provided according to the invention that a

An adhesion promoter is used to improve the adhesion between the applied metallic material and the ceramic or mineral substrate. The adhesion promoter can be, for example, a metal or a metal alloy that is applied directly to the surface of the ceramic or mineral

Substrate. Preferably, it is in its

Properties selected so that they provide optimal

bonding to the ceramic or mineral substrate and to the metallic material applied to the bonding agent. In this way, the

Bonding of the metallic material to the ceramic or mineral substrate can be improved. The application of the

The adhesion promoter is also applied to the recess.

For this purpose, the adhesion promoter preferably has a low

contact angle so that an optimal connection can be achieved. In the case of metallic adhesion promoters, the bond between the adhesion promoter and the metallic material applied to it can also be strengthened by a positive connection in the form of a metallic bond and in particular by the formation of an alloy at the interface between the two metals.

The bonding agent can also be used to promote the

Connection process to the low

Thermal expansion coefficient of the ceramic or mineral substrate.

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LU502912 ductile alloying elements are used to reduce the thermally induced stresses due to the different thermal expansion coefficients in the

boundary layer can compensate.

Copper or titanium, for example, can be used as an adhesion promoter.

Preferably, the removal of a region of the surface by the laser beam and the application of the metallic material are carried out simultaneously. This makes it possible to carry out the process chain for the

Application of the metallic material - if necessary, prior application of the adhesion promoter - in a single

process step is carried out. For this purpose, in accordance with laser cladding, a mixture of an inert

Carrier gas and a fine-grained metallic material. The metallic material melted by the laser radiation, for example, can also be melted by the laser beam or the heat of the ceramic or mineral substrate and before the

Solidification flows into the depression.

Furthermore, it is possible and provided according to the invention that the production of the recess takes place in a separate

Step before the application of the metallic material.

For this purpose, the deepening in a separate

Process step using the surface-directed

Laser radiation, while in a second subsequent process step the metallic

Material is introduced into the recess and melted. For this purpose, a

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LU502912

Device with a laser device can be used, or the creation is done by means of the application device

The recess can also be created by an etching process with an etching compound or by other mechanical

Furthermore, the ceramic or mineral substrate can be provided with the desired recesses during production, for example by using suitable molds.

In an advantageous embodiment of the invention, it is provided that the laser beam generates a working area between 0.2 and 3 mm. This allows

Form depressions with a deposit of metallic structures in a large area. The dimensions of the

The deepening is essentially determined by the area of the

working area and thus the cross-section of the

Laser beam and the power of the laser beam.

In an advantageous implementation of the inventive concept, it is provided that an application device with a

Powder nozzle for generating a coaxial continuous

The powder nozzle can have a circumferential annular gap that surrounds the emitted laser beam, or it can also have

Multi-jet nozzles are used, which have several discrete

Powder nozzles that are arranged so that the injected metal powder meets in a common focus.

Advantageously, the invention provides that a metal oxide and/or a nitride is used as the ceramic substrate

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LU502912 and/or a silicate is used. Preferably, aluminum oxide Al:03 can be used as the ceramic substrate.

Advantageously, the invention optionally provides that the metallic material used is copper and/or titanium and/or aluminium and/or vanadium and/or silver and/or

Iron and/or gold and/or an alloy thereof is used. Titanium or a titanium alloy such as Ti-6A1-4V can preferably be used as the metallic material.

Further advantageous embodiments of the method for

Deposition of a metallic material on a ceramic or mineral substrate with a

Application device are based on the following

Drawing illustrates this. It shows:

Figure 1 shows a method according to the invention for depositing a metallic material on a ceramic or mineral substrate using an application device, wherein a laser beam is directed onto the surface of the ceramic or mineral substrate,

Figure 2 shows the process of Figure 1, wherein the surface of the ceramic or mineral substrate is selectively removed to form a depression,

Figure 3 shows the process from step 2, where the resulting

A metallic material is applied to the depression,

Figure 4 shows a comparison of a contact angle between a

Liquid drops on a planar surface and a

Drops of liquid in the depression,

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LU502912

Figure 5 shows a

Circuit board with applied conductor tracks made of the metallic material, and

Figure 6 is a sectional drawing along section line VI-VI of Figure 5.

Figures 1 to 3 schematically show a variant of the method according to the invention for depositing a metallic material on a ceramic or mineral substrate using an application device.

Figure 1 shows an application device 1 with a

Energy source 2 in the form of a laser device 3.

With the help of the laser device 3, a laser beam 4 is directed onto the surface 5 of a ceramic or mineral

substrate 6 in the form of a plate. The laser beam 4 directed onto the surface 5 defines on the

Surface a working area 7. The application device 1 further comprises a powder nozzle 8 arranged on the application device 1, with which a continuous powder gas jet 9 of a carrier gas and a finely distributed metallic material is sprayed along a

Powder gas path 10 is directed onto the surface 5 of the ceramic or mineral substrate 6 in the area of the working area 7. The powder gas directed onto the surface 5

Laser beam 4 heats the ceramic or mineral

Substrate 6 within an effective range 11.

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LU502912

Due to the high power density of the laser beam 4, the

Working area 7, the surface 5 of the ceramic or mineral substrate 6 in this area is removed piece by piece and removed from the surface 5. By the

Removal of the material 12 may cause a

Cracking caused by heat, which could lead to failure of the ceramic or mineral substrate 6, is prevented. By dissolving the material 12, a

Recess 13 is worked out on the surface 5 of the ceramic or mineral substrate 6. Figure 2 shows the process step of forming the recess 13.

Metallic material 14 introduced into the recess 13 through the powder nozzle 8 is

Laser radiation 4 melts and flows into the recess 13, solidifies there and forms a material deposit in the recess 13. This process step is described in

Figure 3 shows this.

Figure 4 shows the advantage of the inventive

The process is illustrated using a schematic view.

On the left side, the application of a molten metallic material 14 as a liquid drop on a planar ceramic or mineral substrate 6 is shown. The wetting of the surface 5 by the

Liquid drop depends on the

Cohesive forces within the liquid drop and the

Adhesion forces of the liquid drop against the

Surface. As in the case of a metallic

Material 14 the cohesive forces within the

Liquid drop the adhesion forces so the

Liquid drops take the shape of a sphere and the

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LU502912

Surface only touch at a small contact area 15. In this case the contact angle 6 16 - the

Angle that a drop of liquid forms on the surface of a

solid to the surface - greater than 90 °.

Due to the v-shaped geometry of the recess 13 with an acute angle, the contact angle 6 16 of a

of the liquid drop in the depression 14 is always less than 90 °C, whereby complete wetting of the side areas and the bottom area of the depression 13 is achieved. The

Contact angle © 16 of a liquid drop in the depression according to the invention is shown in Figure 3 on the right

page shown.

Figure 5 shows a circuit board 17 produced by the method according to the invention with applied conductor tracks 18 made of the metallic material 14, while Figure 6 shows a

Sectional drawing of circuit board 17 along the cutting line

VI-VI from Figure 5. The v-shaped

Depressions 13 can be seen.

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LU502912

REFERENCE SYMBOLS TTI® STE 1 Application device 2 Energy source 3 Laser device 4 Laser beam 5 Surface of the ceramic or mineral substrate 6 Ceramic or mineral substrate 7 Working area 8 Powder nozzle 9 Powder gas jet 11 Powder gas path 11 Effective area 12 Material removed from the surface 13 Recess 14 Metallic material 15 Contact surface between metallic material and the

Surface of the ceramic or mineral substrate 16 Contact angle 17 Circuit board 18 Conductor track

Claims (11)

- 19 - PON 3345 P LU LU502912 PATENT CLAIMS 1. Method for depositing a metallic material (14) on a ceramic or mineral substrate (6) with an application device (1), wherein a high-energy beam is directed onto a surface (6) of the ceramic or mineral substrate (5) by an energy source (2) arranged on the application device (1), wherein the metallic material (14) is applied to a region of the surface (6) of the ceramic or mineral substrate (5) with the aid of the application device (1), wherein the metallic material (14) is at least partially melted with the high-energy beam, so that after the metallic material (14) has solidified, the metallic material (14) is deposited as a material deposit on the surface (5) of the ceramic or mineral substrate (6), wherein the high-energy beam impinging on the surface (5) of the ceramic or mineral substrate (6) defines a working area (7), wherein the position the working area (7) on the surface (5) can be changed by a relative displacement of the surface (5) of the ceramic or mineral substrate (6) and the energy source (2), characterized in that a depression (13) is made in the working area (7) on the surface (5) of the ceramic or mineral substrate (6), the material being applied into the depression (13). 2. Method according to claim 1, characterized in that the energy source (2) is a laser beam (4) emitting - 20 - PON 3345 P LU LU502912 laser device (3), wherein the surface (5) is selectively removed by the laser beam (4) directed onto the surface (5), so that the recess (13) on the surface (5) is formed by the removed material (12). 3. Method according to claim 1 or 2, characterized in that the depression (13) introduced into the surface (5) of the ceramic or mineral substrate (6) is a V-shaped depression with an acute angle. 4. Method according to one of claims 1 to 3, characterized in that the metallic material (14) introduced into the recess (13) and melted has a contact angle (16) © < 90°. 5. Method according to one of the preceding claims, characterized in that an adhesion promoter is used to improve the adhesion between the applied metallic material (14) and the ceramic or mineral substrate (6). 6. Method according to one of the preceding claims, characterized in that the removal of a region of the surface (5) by the laser beam (4) and the application of the metallic material (14) are carried out simultaneously. 7. according to one of the preceding claims, characterized in that the production of the recess (13) takes place in a separate step before the application of the metallic material (14). - 21 - PON 3345 P LU LU502912 8. Method according to one of the preceding claims, characterized in that a working area (7) between 0.2 and 3 mm is generated by the laser beam (4). 9. Method according to one of the preceding claims, characterized in that an application device (1) with a powder nozzle (8) is used to generate a coaxial continuous powder gas jet (9). 10. Method according to one of the preceding claims, characterized in that a metal oxide and/or a nitride and/or a silicate is used as the ceramic substrate (6). 11. Method according to one of the preceding claims, characterized in that copper and/or titanium and/or aluminum and/or vanadium and/or silver and/or iron and/or gold and/or an alloy thereof is used as the metallic material (14).