WO2013163993A1

WO2013163993A1 - Metal-ceramic substrate and process for producing a metal-ceramic substrate

Info

Publication number: WO2013163993A1
Application number: PCT/DE2013/100158
Authority: WO
Inventors: Andreas Meyer; Christoph WEHE; Karsten Schmidt; Jürgen SCHULZ-HARDER
Original assignee: Curamik Electronics Gmbh
Priority date: 2012-04-30
Filing date: 2013-04-30
Publication date: 2013-11-07
Also published as: DE102012103786A1; DE102012103786B4

Abstract

The invention relates to a metal-ceramic substrate and also to a process for the production thereof, comprising at least one ceramic layer (2), which is provided on a first surface side (2a) with at least a first metallization (3) formed by a film or layer of copper or a copper alloy, and a second metallization (4) connected either directly or indirectly to a second surface side (2b) lying opposite to the first surface side (2a). It is particularly advantageous that the second metallization (4) is formed by a layer of aluminium produced by means of a cold gas spraying process.

Description

The invention relates to a metal-ceramic substrate according to the preamble of patent claim 1 and to a method for producing a metal-ceramic substrate according to the preamble of patent claim 11.

Metal-ceramic substrates in the form of printed circuit boards consisting of an insulating layer of ceramic, of at least one connected to a surface side of the insulating layer of ceramic and for the formation of

Conductor tracks, contacts, contact or mounting areas structured metallization are known in various designs. Such metal-ceramic substrates are often used to construct a power semiconductor module. Here, the cooling of the metal-ceramic substrate is of particular importance. For example, this is done by direct contact of the textured metallization opposite surface side of the ceramic layer or standing with this compound metallization with a cooling medium or a heat sink. In particular, when using fluid or gaseous cooling media, there are special requirements for the metallizations of the metal-ceramic substrates that come into direct contact with them, for example with regard to corrosion resistance and quality of the thermal conductivity. When used in the automotive sector, it is

For example, it is desirable to be able to use the coolant circuit provided for cooling the vehicle also for cooling the substrate

Also known is the so-called "DCB process"("direct copper bonding") for joining metal layers or sheets, preferably Copper sheets or foils with each other and / or with ceramic or ceramic layers, using metal or

Copper sheets or metal or copper foils attached to their

Surface side a layer or a coating ("reflow layer") of a chemical compound of the metal and a reactive gas, preferably oxygen.This example, in US-PS 37 44120 or DE-PS 2319854 described method forms this layer or this coating ("Aufschmelzschicht") a eutectic having a melting temperature below the melting temperature of the metal (eg, copper), so that by laying the metal or copper foil on the ceramic and by heating all layers, these can be joined together, by melting of the metal or copper essentially only in the region of the melting layer or oxide layer. Such a DCB method then has, for example, the following

Procedural steps on:

Oxidizing a copper foil so as to give a uniform copper oxide layer;

Placing the copper foil with the uniform copper oxide layer on the ceramic layer;

Heating the composite to a process temperature between about 1025 to 1083 ° C, for example to about 1071 ° C;

Cool to room temperature. Furthermore, DE 2213115 and EP-A-153618 disclose the so-called active soldering method for joining metal layers or metal foils forming metallizations, in particular also copper layers or copper foils with a ceramic material or a ceramic layer. In this method, which is also used especially for the production of metal-ceramic substrates, at a temperature between about 800 - 1000 ° C, a connection between a Metal foil, such as copper foil, and a ceramic substrate, such as an aluminum nitride ceramic, prepared using a brazing filler, which also contains an active metal in addition to a main component, such as copper, silver and / or gold. This

Active metal, which is, for example, at least one element of the group Hf, Ti, Zr, Nb, Ce, establishes a bond between the braze and the ceramic by a chemical reaction while the bond between the braze and the metal is a metallic braze joint ,

For the production of metallic layers with high thermal conductivity, the cold gas spraying method is also known, the bases of which are described, for example, in EP 0484533 B1. In a cold gas spraying process, metallic spray particles are preferably injected into a cold carrier gas stream having a gas temperature below 800 ° C., and the latter mixed with the

Spray particles laden carrier gas stream subsequently expanded via a nozzle. As a result, the carrier gas flow with the spray particles is accelerated to a velocity exceeding the speed of sound, which subsequently impinges on a component to be coated. Advantageously, the spray particles are not melted in the cold gas spraying, but upon impact with the component to be coated results in a mechanical clamping, a cold welding and / or diverse

Reibschweißprozesse with the surface of the component to be coated, resulting in a layer structure. The metallic coating and the component go directly into each other, and that creates a very dense and low-pore metallic layer. This metallic layer has almost no oxide inclusions and therefore has a very high thermal conductivity to the coated component. Based on the above-mentioned prior art, the present invention seeks to provide a metal-ceramic substrate as well as a To show process for its preparation, which is suitable for cooling by means of fluid or gaseous cooling media and a high

Has thermal conductivity. The object is achieved by a metal-ceramic substrate or a method for its production according to the

Claims 1 bzw.11 solved.

The essential aspect of the metal-ceramic substrate according to the invention is to be seen in that the second metallization is formed by a layer of aluminum produced by means of a cold gas spraying process. By using the cold gas spraying process to produce a

Aluminum coating results in a high metallization

Thermal conductivity. This is particularly advantageous

Metallization of aluminum can also be easily brought into direct contact with fluid or gaseous cooling media, without causing a long-term impairment of the functioning of the metal-ceramic substrate, for example, by corrosion of the second metallization. The second metallization has, for example, a layer thickness between 0.02 mm and 0.5 mm. In a further development of the invention, a sheet-like, plate-like or half-shell-like designed heat sink is provided to form a channel-like receiving space, which is connected at least peripherally with the second metallization. Particularly advantageously, a fluid or gaseous cooling medium can be guided past the receiving space for cooling the substrate which is channel-like as a result.

In a further advantageous embodiment, the metal-ceramic substrate according to the invention is designed such that

that the second metallization on one directly with the second

Surface side of the ceramic layer connected third metallization is applied by cold gas spraying, and / or that the third metallization is structured and / or profiled, and / or

that for the structuring and / or profiling in the third metallization a plurality of recesses of different shape and / or depth are introduced, which are channel-like, slot-like, oval, oblong, circular or diamond-shaped and / or at least partially over at least a quarter of the layer thickness extend the third metallization, and / or that are applied to the second metallization of the surface side outwardly projecting heat sink sections of different shape and / or height by means of cold gas spraying using a mask, wherein the heat sink sections are rib-like, oblong, circular or diamond-shaped and or have a height of 1 mm to 5 mm, and / or

in that the third metallization is made of copper or a copper alloy or of aluminum or an aluminum alloy, and / or that the first metallization has a layer thickness between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.8 mm and / or structured to form contact or bonding surfaces, and / or in that the ceramic layer is made of oxide, nitride or carbide ceramics such as aluminum oxide or aluminum nitride or silicon nitride or

Silicon carbide or aluminum oxide is produced with zirconium oxide and / or has a layer thickness between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.4 mm,

wherein the aforementioned features in turn may each be provided individually or in any combination.

The invention furthermore relates to a method for producing a metal-ceramic substrate comprising a ceramic layer provided on a first surface side with at least one first metallization formed by a foil or layer of copper or a copper alloy, and one either directly or indirectly with one of the first Surface side opposite second surface side

connected second metallization. The essential aspect of

The method according to the invention can be seen in that the second

Metallization of aluminum is produced by means of a cold gas spraying process.

The inventive method is further developed, for example, such that the second metallization on one directly with the second

Surface side of the ceramic layer connected third metallization is applied by cold gas spraying, and / or

that the third metallization is structured and / or profiled, by introducing a plurality of recesses of different shape and / or depth, wherein the recesses are channel-like, slot-like, oval, oblong, circular or diamond-shaped and / or at least partially extend over at least a quarter of the layer thickness of the third metallization, and / or

that the recesses by means of etching, a laser treatment and / or a mechanical machining process, such as sawing in the outwardly directed surface side of the third metallization

be introduced, and / or

that projecting outward on the second metallization

Heatsink sections of different shape and / or height means

Cold gas spraying can be applied using a mask, wherein the heat sink sections are rib-like, oblong, circular or diamond-shaped and / or have a height of 1 mm to 5 mm, wherein the aforementioned features can be used individually or in any combination.

The expressions "approximately", "substantially" or "approximately" in the context of the invention mean deviations from the exact value by +/- 10%, preferably by +/- 5% and / or deviations in the form of changes insignificant for the function.

Further developments, advantages and applications of the invention will become apparent from the following description of

Embodiments and from the figures. All described and / or illustrated features are alone or in any

Combination in principle subject of the invention, regardless of their summary in the claims or their dependency. Also, the content of the claims is made an integral part of the description.

The invention will be described below with reference to the figures

Embodiments explained in more detail. Show it:

Fig. 1 is a simplified sectional view through a

Inventive metal-ceramic substrate with a second, produced by cold gas spraying metallization

Aluminum,

2 is a simplified sectional view of the metal-ceramic substrate according to FIG. 1 with a metal plate connected peripherally to form a guide channel with the second metallization;

Fig. 3 is a simplified sectional view through a

Metal-ceramic substrate according to the invention having a second metalization made of aluminum, which is connected to the ceramic layer via a third metallization, by means of cold gas spraying, 4 is a simplified sectional view through the metal-ceramic substrate according to Figure 3 with a structured third metallization, Figure 5 is a simplified sectional view through the metal-ceramic substrate according to Figure 3 with a profiled third metallization,

6 is a simplified sectional view through the metal-ceramic substrate of Figure 3 with additional heat sink sections and

7 shows a simplified sectional view through a

Metal-ceramic substrate according to the invention with a third metallization projecting beyond a marginal edge analogous to the figure

Third

Figure 1 shows a simplified representation of a section through a

Inventive metal-ceramic substrate 1 comprising at least one ceramic layer 2 with two opposite surface sides, namely a first and second surface side 2a, 2b.

The first surface side 2a is provided with at least a first metallization 3 and the second surface opposite the first surface side 2a

Surface side 2b provided with at least one second metallization 4, wherein the first metallization 3 is formed or produced by a foil or layer of copper or a copper alloy.

The first metallization 3 is preferably formed structured, ie forms a plurality of contact areas or contact surfaces for connection of electronic components. The first, made of copper or one Copper alloy produced metallization 3, for example, has a layer thickness between 0.1 mm and 1, 0 mm, preferably between 0.2 mm and 0.8 mm. The ceramic layer 2 is made of, for example, an oxide, nitride or carbide ceramic such as aluminum oxide (Al 2 O 3) or aluminum nitride (AIN) or silicon nitride (Si 3 N 4) or silicon carbide (SiC) or

Alumina prepared with zirconia (Al2O3 + ZrO2) and has a layer thickness, for example between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.4 mm.

According to the invention, the second metallization 4 is formed by a layer of aluminum produced by means of a cold gas spraying process. The aluminum layer or second metallization 4 produced by cold gas spraying is either directly or indirectly connected to or applied to the second surface side 2b of the ceramic layer 2. By direct or indirect coating of the underside of the metal-ceramic substrate 1 in the form of the second metallization 4 results in a coating with a very high thermal conductivity, which are brought particularly advantageous due to the use of corrosion-resistant aluminum material in direct contact with fluid or gaseous cooling media can. The aluminum layer or second metallization 4 produced by cold gas spraying has, for example, a layer thickness of 0.02 mm to 0.5 mm.

In an embodiment variant of the invention according to FIG. 2, to form a channel-like receiving space 5, a sheet-like, plate-like or half-shell-like heat sink 6 is provided, which is connected at least at the edge to the second metallization 4. The channel-like receiving space 5 is designed in particular for guiding a fluid or gaseous cooling medium. For this purpose, the sheet-like, plate-like or half-shell-like heat sink 6 connected at least in the region of two opposite edge portions 6 ', 6 "by gluing, soldering or otherwise, preferably liquid and / or gas-tight with the generated by cold gas spraying with aluminum particles second metallization 4, with the each

opposite edge portions 4 ', 4 "of the second metallization 4. The heat sink 6 may for example be made of aluminum, a

Aluminum alloy, stainless steel, a magnesium alloy or made of chromium or nickel refined steels.

Also, in a non-illustrated embodiment, the second metallization 4 and / or the heat sink 5 may be formed structured or profiled, for example along the longitudinal axis of the substrate 1, thereby a directed guidance of the fluid or gaseous cooling medium in a predetermined direction, in particular along to force the longitudinal axis of the substrate 1.

For example, when using the metal-ceramic substrate 1 in the automotive sector, the cooling of the metal-ceramic substrate 1 by the inclusion in the existing coolant circuit. For this purpose, the second metallization 4 of the metal-ceramic substrate 1 is at least partially brought into contact with the coolant and, for example, in an embodiment of the substrate 1 according to Figure 2, the coolant of the vehicle coolant circuit through the channel-like receiving space 5 out.

According to the embodiment variants illustrated in FIGS. 3 to 6, the second metallization 4 passes through a third metallization 7 connected directly to the second surface side 2b of the ceramic layer 2

Cold gas spraying applied. The third metallization 7 is here either as a metal layer

approximately uniform thickness (Figures 3 and 6) or in the form of a structured or profiled metal layer (Figures 4 and 5). The third metallization 7 is, for example, by a foil or layer of copper or a copper alloy or of aluminum or a

Made of aluminum alloy whose layer thickness is for example between 0.1 mm and 1.0 mm.

Preferably, first, the third metallization 7 is connected to the second surface side 2b of the ceramic layer 2 and then applied thereto by means of cold gas spraying the second metallization 4 in the form of an aluminum layer, which preferably via the

Edge regions 7 ', 7 "of the third metallization 7 to the exposed

Ceramic layer 2 extends. This results in a complete

Coating of the third metallization 7 by the aluminum layer produced by means of cold gas spraying, which preferably seals these edges against the ceramic layer 2 in a liquid-tight and / or gas-tight manner.

In an advantageous embodiment, a structuring and / or in the third metallization 7 before the coating according to the invention

Profiling introduced to achieve an increase in the surface of the aluminum layer produced by cold gas spraying. The

Structuring and / or profiling of the third metallization 7 takes place, for example, by introducing a plurality of recesses 8

different shape and depth. To suppress the possibly in the

Production of metal-ceramic substrates 1 resulting bi-metal effect, for example, the first and third metallization 3, 7

be approximately the same or similar structured. The recesses 8 may for example be channel-like, slot-like, oval, oblong, circular or diamond-shaped and sections at least over a quarter of the layer thickness of the second metallization 4 extend. Preferably, said recesses 8 have a recess depth of one quarter to three quarters of the layer thickness of the second metallization 4, ie the recess depth may be for example between 0.05 mm and 0.9 mm. The recesses 8 are introduced into the outwardly directed surface side of the second metallization 4, for example, by means of etching, a laser treatment and / or a mechanical machining process, for example sawing. The recesses 8, for example, to increase the

Surface of the third metallization 7 may be introduced in its outwardly facing top in the form of holes, which are preferably distributed in a matrix-like manner over the top. The recesses 8 formed by holes, for example, have a minimum depth of about 0.05 mm and may also extend to the surface of the ceramic layer 2. Alternatively, the holes 8 can also be introduced directly adjacent to one another and / or at least partially overlapping into the surface of the third metallization 7. The introduction of the holes 8 takes place for example by means of an etching process.

In addition, by using a mask on the existing second metallization 4 in the form of an aluminum layer by means

Cold gas spraying heat sink sections 9 also made of aluminum

different shape and height are generated. Such a mask is provided with recesses which are the negative of the

Represent heat sink structure. The heat sink sections 9 can

For example, be rib-like, long-hole, circular or diamond-shaped, which protrude from the surface side of the second metallization 4 to the outside. These may for example have a height of 1 mm to 5 mm. By using the same manufacturing process, the heat sink sections 9 and the second metallization 4 are integral formed, so that advantageously the structuring and / or profiling of the second metallization 4 can be enhanced.

In an alternative embodiment variant according to FIG. 7, analogously to the embodiment variant according to FIG. 3, the second metallization 4 is located directly on the second surface side 2b of the ceramic layer 2

connected third metallization 7 applied by cold gas spraying, wherein the edge portions 7 ', 7 "of the third metallization 7 on the

The edge portions 2 ', 2 "of the ceramic layer 2 protrude away from the surface so that the edge portions 7', 7" of the third metallization 7 accessible from above form fastening sections or mounting surfaces, by means of which a

Mounting or mounting of the metal-ceramic substrate 1 is possible.

Taking into account the materials used for the ceramic layer 2 and the first and third metallizations 3, 7, different methods are suitable for the areal connection of the ceramic layer 2 to the first and third metallizations 3, 7.

Are the first and third metallization 3, 7 made of copper or a

Copper alloy produced, they can be connected to the ceramic layer 2, for example by gluing using a plastic adhesive or a polymer suitable as an adhesive, preferably using an adhesive containing carbon fibers, in particular carbon nanofibers. Alternatively, the surface connection of the

Ceramic layer using the DCB method or by means of the Aktivlötverfahrens done.

If the third metallization 7 is made of aluminum or an aluminum alloy, the connection with the ceramic layer 2 can be achieved, for example, by a "direct aluminum bonding" method ("DAB method") or by gluing using a plastic adhesive or a plastic adhesive Adhesive suitable polymer, preferably using an adhesive containing carbon fibers, in particular carbon nanofibers made.

In addition, in non-illustrated embodiments, the first metallization 3 and / or the second metallization 4 formed in the form of an aluminum layer produced by cold gas spraying can be provided at least partially with a metallic surface layer, for example a surface layer of nickel, gold, silver or nickel, gold and silver alloys. Such a metallic

Surface layer is preferably applied to the ceramic layer 2 or the production of the second metallization 4 after the application of the first metallization 3.

The application of the surface layer takes place in a suitable

Process, for example galvanic and / or by chemical

Separation and / or by spraying or also cold gas spraying.

In particular, when using nickel has the metallic

Surface layer, for example, a layer thickness in the range between 0.002 mm and 0.015 mm.

The invention has been described above by means of exemplary embodiments. It is understood that numerous changes and modifications are possible without thereby underlying the invention

Inventive concept is left. LIST OF REFERENCE NUMBERS

1 Meta 11 - Ceram i c S u b strate

2 ceramic layer

2 ', 2 "edge portions of the ceramic layer

2a first surface side

2b second surface side

3 first metallization

4 second metallization

4 ', 4 "edge portion of the second metallization

5 channel-like recording room

6 heatsinks

6 ', 6 "edge portions of the heat sink

7 third metallization

7 ', 7 "edge portions of the third metallization

8 recesses

9 C ontric Body Des ction

Claims

Patent claims

Metal l-ceramic substrate comprising at least one ceramic layer

(2), which is on a first surface side (2a) with at least one first, through a foil or layer made of copper or a

Metallization formed by copper alloy

(3), and a second metallization (4) connected either directly or indirectly to a second surface side (2b) opposite the first surface side (2a), characterized in that the second metallization (4) is carried out a layer of aluminum produced by a cold gas spraying process is formed.

Metal l-ceramic substrate according to claim 1, characterized in that to form a channel-like receiving space (5) a sheet-like, plate-like or half-shell-like

Heat sink (6) is provided, which is connected at least on the edge to the second metalization (4).

Metal l-ceramic substrate according to claim 1 or 2, characterized

characterized in that the second metalization (4) has a layer thickness between 0.02 mm and 0.5 mm.

Metal l-ceramic substrate according to one of claims 1 to 3, characterized in that the second metal lization

(4) is applied by cold gas spraying to a third metalization (7) which is directly connected to the second surface side (2b) of the ceramic layer (2).

5. Metal-ceramic substrate according to claim 4, characterized in that the third metallization (7) is structured and / or profiled.

Metal-ceramic substrate according to claim 5, characterized in that for structuring and / or profiling in the third

Metallization (7) several recesses (8) of different shapes and / or depths are introduced, which are channel-like, slot-like, oval, slot-shaped, circular or diamond-shaped and / or at least in sections over at least a quarter of the

Layer thickness of the third metallization (7).

Metal-ceramic substrate according to one of claims 4 to 6, characterized in that heat sink sections (9) of different shapes and/or heights projecting outwards from the surface side are applied to the second metallization (4) by means of cold gas spraying using a mask, wherein the

Heat sink sections (9) are designed like ribs, slots, circles or diamonds and/or have a height of 1 mm to 5 mm.

Metal-ceramic substrate according to one of claims 4 to 7, characterized in that the third metallization (7) is made of copper or a copper alloy or of aluminum or one

Aluminum alloy is made.

Metal-ceramic substrate according to one of claims 1 to 8, characterized in that the first metallization (3) has a layer thickness between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.8 mm and/ or is structured to form contact or bonding surfaces. Metal-ceramic substrate according to one of claims 1 to 9, characterized in that the ceramic layer is made of oxide, nitride or carbide ceramics such as aluminum oxide or aluminum nitride or silicon nitride or silicon carbide or aluminum oxide

Zirconium oxide is made and / or has a layer thickness between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.4 mm.

Method for producing a metal-ceramic substrate (2) comprising at least one ceramic layer (2) which is provided on a first surface side (2a) with at least one first metallization (3) formed by a foil or layer made of copper or a copper alloy , and one either directly or indirectly with one of the first surface sides (2a)

opposite second surface side (2b) connected second metallization (4), characterized in that the second metallization (4) is made of aluminum by means of a cold gas spraying process.

Method according to claim 1 1, characterized in that the second metallization (4) is directly connected to the second

Third metallization (7) connected to the surface side (2b) of the ceramic layer (2) is applied by cold gas spraying.

Method according to claim 12, characterized in that the third metallization (7) is structured and/or profiled by introducing a plurality of recesses (8) of different shapes and/or depths, the recesses (8) being channel-like, slot-like, are oval, slotted, circular or diamond-shaped and/or extend at least in sections over at least a quarter of the layer thickness of the third metallization (7).

Method according to claim 1 3, characterized in that the recesses (8) are introduced into the outward-facing surface side of the third metallization (7) by means of etching, laser treatment and/or a mechanical processing process, for example sawing.

Method according to one of claims 1 1 to 14, characterized

characterized in that outwardly projecting heat sink sections (9) of different shapes and/or heights are applied to the second metallization (4) by means of cold gas spraying using a mask, the heat sink sections (9) being rib-like, slot-shaped, circular or diamond-shaped and /or have a height of 1 mm to 5 mm.