EP3325264A1

EP3325264A1 - Substrate for electrical circuits and method for producing such a substrate

Info

Publication number: EP3325264A1
Application number: EP16741600.7A
Authority: EP
Inventors: Andreas Meyer; Karsten Schmidt
Original assignee: Rogers Germany GmbH
Current assignee: Rogers Germany GmbH
Priority date: 2015-07-17
Filing date: 2016-07-18
Publication date: 2018-05-30
Also published as: DE102015111667A1; KR102311944B1; WO2017013073A1; US20180200990A1; WO2017013075A1; KR20180030150A; US10821704B2; EP3325265A1; JP6894425B2; CN107848246A; US20180200989A1; KR20180030151A; US10940671B2; JP2018523593A; CN107848245A; JP6803369B2; JP2018533197A; KR102295797B1

Abstract

The invention relates to a substrate (1, 10) for electrical circuits, comprising at least one metal layer (2, 3, 14) and a paper ceramic layer (11), which is joined face to face with the at least one metal layer (2, 3, 14) and has a top side and bottom side (11a, 11b), wherein the paper ceramic layer (11) has a large number of cavities in the form of pores. Especially advantageously, the at least one metal layer (2, 3, 14) is connected to the paper ceramic layer (11) by means of at least one glue layer (6, 6a, 6b), which is produced by applying at least one glue (6a', 6a'', 6b', 6b'') to the metal layer (2, 3, 14) and/or to the paper ceramic layer (11), wherein the cavities in the form of pores in the paper ceramic layer (11) are filled at least at the surface by means of the applied glue (6a', 6a'', 6b', 6b'').

Description

Substrate for electrical circuits and method for producing such

The invention relates to a substrate for electrical circuits according to the preamble of claim 1 and to a method for producing such a substrate according to the preamble of claim 18.

Substrates for electrical circuits in the form of printed circuit boards are well known.

For this purpose, substrates of this type have a multilayer structure and have at least one insulation layer and at least one metal layer or metallization connected to this insulation layer. The metal layer or metallization is areally connected to the insulation layer either directly or optionally via further metal or insulation layers and is structured to form conductor tracks, contacts, contact surfaces and / or connection surfaces in a plurality of metalization surface sections. In particular when using such substrates in the field of

Power electronics, and so-called "low voltage" applications,

For example, to build power semiconductor modules in one

Voltage range of less than 2.5 kV, it is necessary that the substrates or their insulating layer, a high insulation resistance, i. Voltage and

Have dielectric strength.

In the field of power electronics, therefore, metal-ceramic substrates are often used whose insulation layer is characterized by at least one high

Insulation resistance having ceramic layer is formed. The ceramic layer is made of, for example, an oxide, nitride or carbide ceramic such as alumina

(Al2O3) or aluminum nitride (AIN) or silicon nitride (Si3N4) or silicon carbide (SiC) or made of aluminum oxide with zirconium oxide (Al2O3 + ZrO2). For surface connection of the ceramic layer with at least one metal layer forming a metallization find depending on the used

Ceramic material and / or the metal to be bonded metal layer

different, per se known manufacturing method use, namely, for example, a "direct copper bonding" method, a "direct aluminum bonding" method and an "active metal bonding" method and costly. Also, when using conventional ceramic layers, the

Shaping limited.

Furthermore, processes for producing highly filled papers, for example from DE 102006022598 A1, US 2009011208 A1 or US Pat. No. 8608906 B2, are known in which the paper structure is enriched in the papermaking process by up to 85% by weight with functional fillers, for example with a sinterable ceramic powder, highly adsorptive powder or powder with good

Heat storage capacity. These ceramic fillers have the known electrical insulation properties. As ceramic fillers or

Main fillers for the paper structure are, for example, in particular Al 2 O 3, Si 3 N 4, AlN, ZrO 2, MgO, SiC and BeO or else a combination such as ZTA, in particle sizes of <5 μm, preferably <1 μm. Further sintering aids are the ceramic fillers or secondary fillers respective main fillers, namely Y 2 O 3, CaO, MgO, SiO 2, etc., were incorporated into the paper structure. From this preceramic ceramic structure enriched with sinterable ceramic fillers, a so-called sintered paper or a paper ceramic is optionally produced after a further deformation process by thermal conversion, inter alia by carrying out a two-stage thermal conversion. As part of the first stage of the thermal conversion, the organic components of the preceramic papers, such as pulp, starch and latex, are oxidatively removed to form a so-called "brownling." Subsequently, in a second stage of the thermal conversion, the "brownling" is sintered The result is a ceramic material with the typical bending strength of a ceramic. The microstructure of this sintered paper or of the paper ceramic shows, among other things, the typical for ceramics Material properties, for example, a high insulation resistance. In such paper ceramics, the advantages of ceramic materials can be combined with the papering advantages, such as ease of deformation and light weight. Disadvantageous, however, arise from the oxidative removal of the organic components, in particular the cellulose fibers as a binder of the paper structure in the paper ceramics pore-shaped cavities, which lead to a porosity of the paper ceramic material of less than 50%. The porosity of the paper-ceramic material in particular contributes

Use of the paper-ceramic material in substrates for electrical circuits to deteriorate their insulation resistance.

Based on the above-mentioned prior art, the present invention seeks to provide a substrate for electrical circuits and an associated method for producing such a substrate, which is simple and inexpensive to produce compared to the known substrates and its insulation layer made of a paper ceramic a has improved insulation resistance. The object is achieved by a substrate according to the

Claim 1 and a method according to claim 18 solved. The essential aspect of the substrate according to the invention for electrical

Circuits can be seen in that the at least one metal layer is connected via at least one adhesive layer with the paper ceramic layer, which is prepared by applying at least one adhesive to the metal layer and / or on the paper ceramic layer, wherein by means of the applied adhesive, the pore-shaped cavities in the paper ceramic layer filled at least on the surface side. In addition to the production of the adhesive bond between the at least one metal layer and the paper-ceramic layer, the residual porosity of the paper-ceramic layer is particularly advantageous due to at least the surface side

Fill their pore-shaped cavities significantly reduced and thus the

Insulation properties of the substrate significantly improved. After filling with adhesive, the paper-ceramic layer particularly advantageously has a porosity of less than 10%, preferably less than 5%. In this case, a paper-ceramic layer according to the invention is understood as meaning a paper structure enriched in papermaking with a sinterable ceramic filler, preferably alumina powder, from which a preceramic paper structure is produced. The preceramic paper structure is subjected to a two-stage thermal conversion process and firstly from the preceramic paper structure ("green body") a "Braunling" is produced in which the organic components of the preceramic paper structure, such as pulp, starch and latex are oxidatively removed. Subsequently, in the second stage, the "Braunling" is fed to a sintering process, whereby a ceramic material, namely the paper ceramics, is produced.Preferably, the paper ceramics layer exhibits the typical material properties of a ceramic material, namely a high bending and insulation resistance the well-known ceramic layer in the case of metal-ceramic substrates

Manufacturing process as well as in the design of the paper-ceramic layer. The paper-ceramic layer is lighter in comparison to a conventional ceramic layer and individually deformable prior to the implementation of the thermal conversion process. Also advantageously, the starting material of the paper-ceramic layer can be stored and further processed as a roll product due to the deformability.

The paper-ceramic layer is produced particularly advantageously from a paper structure enriched with a sinterable ceramic filler by means of thermal conversion, in which the proportion of sinterable ceramic fillers of the enriched paper structure is greater than 80% by weight, preferably between 80 and 90% by weight. As ceramic fillers of the paper structure, Al 2 O 3, Si 3 N 4, AlN, ZrO 2, MgO, SiC, BeO or a combination thereof and associated typical sintering aids such as Y 2 O 3, CaO, MgO, SiO 2 are provided.

In a preferred embodiment, the metal layer or the

Composite layer via at least one adhesive layer or a solder layer connected to the paper-ceramic layer, depending on the respective formation of the metal layer or composite layer. In an alternative embodiment variant, the at least one metal layer is connected to at least one further metal layer to form a composite layer. The composite layer according to the invention is in turn connected to the paper-ceramic layer via an adhesive layer. It is understood that the substrate may also comprise a plurality of composite layers, for example a first and second

Composite layer, which are connected at the top and bottom of the paper-ceramic layer in each case over an adhesive layer surface.

Advantageously, the paper-ceramic layer has a layer thickness between 50 .mu.m and 600 .mu.m, preferably 80 .mu.m and 150 .mu.m, and an E-modulus between 90 GPa and 150 GPa.

In a preferred embodiment variant, the paper-ceramic layer has a top and bottom side, wherein the upper side is connected in a planar manner by means of an adhesive layer to a first metal layer and the underside by means of a further adhesive layer to a second metal layer. Such a three-layer substrate has good insulation properties for use in the "low-voltage" range and high mechanical stability with low substrate thickness.

For the production of the adhesive layer, an adhesive having a viscosity of less than 30 Pas is particularly advantageously used for producing an adhesive layer having a layer thickness of between 1 and 30 μm, preferably between 1 and 10 μm. The layer thickness gives the distance between the top and bottom sides / or bottom of the paper-ceramic layer and the surface of the adjoining layer, in particular metal or composite layer.

The adhesive layer is made of a chemically and / or physically curable adhesive from the group of polyurethanes, epoxy resins, polyimides or

Methyl metacrylate manufactured, whereby the penetration depth of the adhesive into the

Paper ceramic layer or its pore-shaped cavities preferably at least one third of the adjoining the adhesive layer layer thickness of the paper-ceramic layer. Thus, at least one side surface becomes advantageous One third of the pore-shaped cavities of the paper-ceramic layer are filled with adhesive, preferably both from the top and from the underside of the paper-ceramic layer, ie in total at least two-thirds of the pore-shaped cavities. In an alternative embodiment variant, the pore-shaped cavities in the paper-ceramic layer are almost completely filled with adhesive in order to obtain optimum insulation properties. The adhesive layer can

For example, be made of at least two different adhesives with possibly a different viscosity. Furthermore, the at least one metal layer is advantageously produced from copper, aluminum, gold, silver, tin, zinc, molybdenum, tungsten, Cr or their alloys. For example, the composite layer may comprise a metal layer and at least one aluminum layer or aluminum alloy layer, wherein in this embodiment variant the metal layer is preferably realized in the form of a copper layer or copper alloy layer. The layer thickness of the copper layer or copper alloy layer is then, for example, between 35 μνη and 2 mm and the layer thickness of the aluminum layer or aluminum alloy layer between 10 jum and 300 μνη. Further advantageously, the aluminum layer of the

Bonding layer to produce an anodized layer on the opposite surface of the metal layer to be anodized to achieve adhesion improvement. In an advantageous embodiment variant, the aluminum layer of the composite layer has an aluminum-silicon layer.

The invention likewise provides a process for the production of a substrate for electrical circuits comprising at least one metal layer and at least one paper ceramic layer having a top and bottom, in which at least the top or bottom surface are connected to the at least one metal layer, wherein the paper ceramic layer Variety of pore-shaped

Having cavities. An essential aspect of the method according to the invention is to be seen in that on the at least one metal layer and / or on the top and / or bottom of the paper ceramic layer adhesive for the production of at least one adhesive layer is applied surface, in such a way that by means of the applied adhesive the pore-shaped voids in the paper-ceramic layer be filled at least on the surface side. The applied in a suitably sized amount surface adhesive penetrates at least superficially

pore-shaped cavities and closes them at least partially, so that at least in the adjoining the adhesive layer surface side

Section of the paper ceramic layer, the porosity or residual porosity of

Paper ceramic layer is reduced. Here are different examples

Adhesive variants possible.

In a first embodiment, for example, the adhesive is applied over the surface only on the surface side of the at least one metal layer and then glued to the top or bottom of the paper-ceramic layer.

Here, the adhesive comes after the joining of the metal layer with the

Paper ceramic layer in contact. In a second embodiment variant, the adhesive is applied over the surface exclusively to the top and / or bottom side of the paper-ceramic layer and then bonded to the at least one metal layer. Here, advantageously, at least partial filling of the pore-shaped cavities takes place already during adhesive application, i. before the actual joining process.

In a third embodiment, the adhesive is applied both to the

Surface side of the at least one metal layer and applied to the top and / or bottom of the paper ceramic layer surface and then both glued together. As a result, both an optimal filling of the pore-shaped cavities and the production of a bonded joint with high

Connection strength possible, especially in an at least partial curing of the adhesive application before the actual joining process. In another

Variant are applied to the at least one metal layer and the top and / or bottom of the paper ceramic layer at least two different adhesives, the viscosity of the adhesive applied to the paper ceramic layer adhesive is preferably less than the viscosity of the on the

Metal layer applied adhesive. Advantageously, this can be filled the pore-shaped cavities find a less liquid adhesive than for the production of the adhesive bond with the metal layer use.

In a fourth embodiment, the adhesive is applied over the surface exclusively on the top or bottom of the paper ceramic layer, wherein the

Adhesive amount is dimensioned such that the pore-shaped cavities are completely filled. The filling of the pore-shaped cavities thus takes place over one side of the paper-ceramic layer. Particularly advantageously, the amount of adhesive used is set such that, in the connected state, an adhesive layer having a layer thickness in the range between 1 and 30 μm, preferably between 1 and 10 μm, is formed.

The pore-shaped cavities of the paper-ceramic layer are advantageously filled with adhesive in such a way that the paper-ceramic layer after filling a

Porosity below 10%, preferably below 5%.

Further advantageous by means of the applied adhesive, the pore-shaped cavities along at least one third of the layer thickness of

Filled with paper-ceramic layer.

The expressions "approximately", "substantially" or "approximately" in the context of the invention mean deviations from the respective 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 exemplary embodiments and from the figures. All are described and / or illustrated

Features 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 explained in more detail below with reference to the figures of exemplary embodiments. 1 is a simplified schematic Schnittdarstel ment by a

A substrate according to the invention comprising a first metal layer and a paper-ceramic layer bonded thereto via an adhesive layer,

Fig. 2a-c is a simplified depicting development of selected steps of the method for

Manufacture of a substrate according to the invention comprising a first and second metal lschicht and a recorded therebetween and connected by means of adhesive layers paper ceramic layer and

Fig. 3 is a simplified schematic sectional view through a

A substrate according to the invention comprising a composite layer and a paper-ceramic layer bonded thereto via an adhesive layer.

Figure 1 shows in a simplified schematic representation a section through an inventively designed substrate 1 for electrical circuits, which has a plate-shaped and multilayer structure, i. in the form of a

Printed circuit board is formed. The substrate 1 according to the invention is particularly suitable for so-called "low-voltage" applications, ie for the construction of electrical circuits in a voltage range of less than 2.5 kV. The substrate 1 according to the invention for electrical circuits here comprises at least one first metalization or metal 2 and a paper-ceramic layer 1 1 which is connected in a planar manner to the at least one first metalization and metal layer 2, wherein the paper-ceramic layer 1 1 has a multiplicity of pore-shaped cavities due to the production

Manufel development of very thin paper ceramic layers 1 1 can in their

Further processing also causes defects in the form of cracks, which could easily lead to a deterioration of the insulation properties. In the present exemplary embodiment according to FIG. 1, the paper-ceramic layer 11 has an upper and lower side 11a, 11b, and the first metallization layer or metal layer 2 is connected in a planar manner to the upper side 11a of the paper-ceramic layer 11. In an alternative, preferred embodiment, the substrate 1 in addition to the first metal layer 2, a second metal layer 3, which is connected to the underside 11 b of the paper-ceramic layer 11 area. By way of example, the paper-ceramic layer 11 has a first layer thickness d1 and the first or any second metal layer 2, 3 present a second layer thickness d2.

In the context of the invention, a paper-ceramic layer 11 or a paper-based ceramic is understood as meaning a paper structure enriched in papermaking with sinterable ceramic, preferably powdery, fillers, from which a preceramic paper structure is produced in an intermediate step. Preferably, the proportion of sinterable ceramic filler of the preceramic paper structure is greater than 80 wt .-%, preferably between 80 and 90 wt .-%. The production of such

In principle, suitable ceramic fillers or main fillers of the paper structure are Al.sub.2O.sub.3, Si.sub.3N.sub.4, AlN, ZrO.sub.2, MgO, SiC and BeO or combinations such as ZTA, in particle sizes of <5 .mu.m < 1 vm. Further typical ceramic fillers or secondary fillers are the respective typical ones

Sintering aids of the main fillers, namely, for example, Y2O3, CaO, MgO, SiO2, etc. included in the paper structure. The corresponding preceramic paper structure is then subjected to a two-stage thermal conversion process and first a "Braunling" is produced from the preceramic paper structure ("green body"), in which the organic components of the preceramic paper structure, such as pulp, starch and latex are oxidatively removed. Then in the second stage of the "Braunling" one

Sintering process, whereby a ceramic material, namely the

Paper ceramics with the typical material properties of a ceramic material is created, such as a high bending and insulation strength. The However, paper-ceramic layer 11 is compared to a conventional one

Ceramic layer lighter and before performing the thermal

Implementation process individually deformable. Also, the starting material of the paper-ceramic layer 1 1, namely the preceramic paper structure due to the deformability as Rol lenware stored and further processed. The

For example, paper-ceramic layer 1 1 used according to the invention has a layer thickness d 1 between 50 μνη and 600 μνη, preferably 80 μνη and 1 50 μνη and has an E-modulus between 90 GPa and 1 50 GPa. In the context of the described manufacturing process of the paper ceramic layer 1 1 is formed by the oxidative removal of the organic components in

Paper texture a variety of pore-shaped cavities. The pore-shaped cavities can be opened on the surface side or vol lständig in the

Paper ceramic layer 1 1 are included, i. within the

Paper ceramic layer 1 1 extend. The pore-shaped cavities here often have the shape of the cellulose fibers removed by oxidation, and are approximately evenly distributed over the entire paper-ceramic layer 1 1. The

Paper ceramic layer 1 1 has due to the large number of pore-shaped cavities, for example, a porosity or residual porosity smaller than 50%, preferably less than 30%, through which the insulation strength of the paper ceramic layer 1 1, in particular when using it in a substrate 1 for electrical

Circuits is impaired. Here is the starting point of the invention.

According to the invention, the at least one metal lschicht 2, 3 via at least one adhesive layer 6, 6a, 6b connected to the Papierkeramikschicht 1 1, namely the at least one adhesive layer 6, 6a, 6b by applying at least one adhesive 6a ', 6a ", 6b ', 6b "on the at least one metal lschicht 2, 3 and / or on the upper and / or U nterseite 1 1 a, 1 1 b of the paper-ceramic layer 1 1 generated such that by means of the applied adhesive 6a', 6a" , 6b ', 6b ", the pore-shaped cavities in the paper-ceramic layer 1 1 at least at the surface, ie in the region of the top and / or bottom 1 1 a, 1 1 b of the paper-ceramic layer 1 1 are at least partially filled. Thus, at least the surface side open pore-shaped cavities in the paper-ceramic layer 1 1 by means of Adhesive 6a ', 6a ", 6b', 6b" closed. The adhesive is preferably at least partially in on the upper and / or U nterseite 1 1 a, 1 1 b of the paper ceramic layer 1 1 subsequent or arranged in its area pore-shaped cavities and possibly ebens existing cracks in the paper ceramic layer 1 1 in the frame the manufacture ment of the adhesive bond between the at least one metal lschicht 2, 3 and the paper ceramic layer 1 1 introduced, ie the adhesive 6a ', 6a ", 6b', 6b" penetrates into the pore-shaped cavities and closes them vol lständig in the to the upper and / or U nterseite 1 1 a, 1 1 b of the paper-ceramic layer 1 1 subsequent section of the paper-ceramic layer 1 1. Advantageously, this reduces the existing porosity of the paper-ceramic layer 11 to less than 10% and thus significantly improves its insulation resistance. Preferably, more than half of the pore-shaped cavities in the paper-ceramic layer 11 are at least partially filled with the adhesive, after the adhesive layers 6, 6a, 6b produced by the adhesive application 6a ', 6a ", 6b', 6b". In Figures 1, the penetration depth of the adhesive application 6a ', 6b' in the pore-shaped cavities of the paper ceramic layer 1 1 indicated by a dashed line drawn, ie the adhesive 6a ', 6b' is at least up to a third of the adhesive layer 6 anschl penetrating layer thickness d 1 penetrated into the paper-ceramic layer 1 1. The penetration depth of the adhesive 6a ', 6b' is thus for example at least one third of the layer thickness d 1 of the paper-ceramic layer 1 1.

Starting from a plurality of pore-shaped cavities having, ie porous paper ceramic layer 1 1 and the at least one metal lschicht 2, 3, they are so provided with an adhesive coating 6a, 6b, so that in the connected state, an adhesive layer 6, 6a, 6b with a layer thickness d3 is formed in the range between 1 and 30 μνη, preferably between 1 and 10 μνη. The quantity of glue required for this purpose is dimensioned in such a way that it exceeds the predetermined volume by the desired layer thickness d3 and the dimensions of the metal layer 2, 3 or paper-ceramic layer of the adhesive layer 6, 6a, 6b, in such a way that with the additional amount of adhesive not only the pore-shaped cavities can be at least partially filled, but also, if necessary, a compensation of the surface roughness of the respective metal layer 2, 3 or the upper and / or lower surface 11a, 11b of the paper-ceramic layer 11 takes place. The adhesive application can be carried out using known methods, wherein in particular a pre-hardening of the applied adhesive, in particular a temperature treatment can be carried out to optionally in the adhesive volatile components such as solvents or reaction products to remove.

In the production of a substrate 1 according to the invention, the adhesive application can be made to different variants. In principle, at least one paper ceramic layer 11 and at least one metal or

Metallization layer 2, 3 and the time required for the preparation of the adhesive joints adhesive 6a ', 6b', 6a ", 6b" provided. By means of a preferably automated manufacturing process, starting from this in the

subsequent steps, an adhesive bond via at least one adhesive layer 6, 6a, 6b between the at least one paper ceramic layer 11 and at least one metal or metallization layer 2, 3 generated. The production of the adhesive layer 6, 6a, 6b or the adhesive application 6a ', 6a ", 6b', 6b" required for this purpose and thus also the filling of the pore-shaped cavities of the paper-ceramic layer 11 can be effected by means of different process variants.

For example, in a first embodiment variant, the adhesive 6a ", 6b" can be applied exclusively to the respective surface side of the metal layer 2, 3, and subsequently subsequently adhesively bonded to the top or bottom 11a, 11b of the paper-ceramic layer 11. Alternatively, the adhesive 6a ', 6b' exclusively on the top and / or bottom 11a, 11b of the

Paper ceramic layer 11 are applied and then the respective

Metal layer 2, 3 are bonded hereby. Analogously, the adhesive 6a ', 6b', 6a ", 6b" according to the embodiment shown in Figures 2a to 2c, both on the top and / or bottom 11a, 11b of the paper-ceramic layer 11 and on the metal layer 2, 3 applied become.

By appropriate joining of the with the respective adhesive application 6a ', 6b', 6a ", 6b" provided paper ceramic layer 11 with the metal layers 2, 3 arise then the desired adhesive layers 6a, 6b, which are composed of the adhesive applications 6a ', 6b', 6a ", 6b" and in addition to the preparation of the mechanical connection between the paper ceramic layer 11 and the respective metal layer 2, 3 beyond an at least superficial filling the Ensure pore-shaped voids in the paper-ceramic layer 11.

Finally, it is also conceivable to apply the adhesive 6a ', 6b' only over the upper side 11a or the lower side 11b of the paper-ceramic layer 11 and to transport it via the pore-shaped cavities to the respectively opposite lower or upper side 11b, 11a, i. to oversaturate the paper-ceramic layer 11 by means of a single-sided adhesive application 6a ', 6b'. In this embodiment, a nearly complete filling of the pore-shaped cavities of

Paper ceramic layer 11 required. The layers provided with the respective adhesive application, in particular the paper-ceramic layer 11 and / or the metal layers 2, 3, are preferably joined using a lamination process, namely under one

predetermined pressure and / or temperature. The pressure is in this case dimensioned such that an areal homogeneous and bubble-free connection of the metal layers 2, 3 is ensured on the paper ceramic layer 11. Preferably, in this case, the deflection of the substrate 1 is reduced to a minimum. For example, roll and / or flat laminators can be used in the lamination process.

As adhesives for the production of the adhesive layer 6, 6 'different adhesives can be used, which have a temperature stability of at least 100 ° C after curing. For example, chemically and / or physically hardenable adhesives from the group of polyurethanes, epoxy resins, polyimides and methyl methacrylate can be used, which are used as one or two

Component adhesives are applied and cure under temperature increase and / or pressure increase. The correspondingly cured adhesive layers 6, 6a, 6b between the metal layers 2, 3 and the paper-ceramic layer 11 then preferably have a temperature stability of 100 ° C. to 350 ° C. Further, to increase the thermal conductivity of the adhesive layer 6, 6a, 6b, respectively used adhesive finely dispersed particles which, although electrically non-conductive, but have a good thermal conductivity, namely, for example, Si3N4, ALN or AL203 mixed. However, adhesives or adhesives of low viscosity are preferably used, namely

preferably less than 30 Pas to the porous top and bottom 1 1 a, 1 1 b of the

Paper ceramic layer 5 to fill and thus increase the insulation resistance of the substrate 1. Also, for the preparation of the adhesive layers 6, 6a, 6b different adhesives may be used, which for example a

have different viscosity. For example, the adhesives 6a ', 6b' provided for filling the pore-shaped cavities and producing the adhesive bond, which are applied directly to the top and / or bottom 11a, 11b of the paper-ceramic layer 11, should have a low viscosity, to ensure easy penetration into the pore-shaped cavities. When applying an additional adhesive 6a ", 6b" to the metal layers 2, 3 for producing the adhesive layers 6a, 6b, different and / or thicker adhesives having a higher viscosity can then be used.

The metal layers or metallization layers 2, 3 are produced, for example, using thin metal sheets or metal foils. When

Starting materials may be, for example, copper, aluminum, gold, silver, tin, zinc, molybdenum, tungsten, Cr or their alloys. Also, the use of composites, i. Laminates or powder metallurgical

Mixtures of different metals possible. Depending on the particular material used, the metal layers 2, 3 used have layer thicknesses d2 of between 10 μm and 5 mm. Also known per se

Resistance alloy materials sold under the product names manganin, ceranin or Isaohm, for the production of the metal layers 2, 3 apply. The top and bottom 1 1 a, 1 1 b of the paper-ceramic layer 5 can be bonded to metal layers 2, 3 or laminate or composite layers produced from different metals, for example a combination of a copper layer and an aluminum layer or a combination of one Manganinschicht and an aluminum layer. The layer thicknesses d2 of the

Metal layers 2, 3 may be the same or different, irrespective of the layer thickness d1 of the paper-produced ceramic or

Paper ceramic layer 11.

By way of example, the second metal layer 3 or composite layer can form or have a heat sink, wherein the metal layer forming the heat sink can have a surface enlargement profile on its surface opposite the adhesive layer 6 '

different shape, in particular with regard to the shape, arrangement and depth of existing recesses may be formed.

The substrates 1 according to the invention serve as printed circuit boards for electrical or electronic circuits or circuit modules, in particular for electronic power circuits. For this purpose, at least the first metal layer 2 by means of known masking and etching technologies in several

Metallisierungsabschnitte structured that form, for example, interconnects, contact and / or pads. Due to the very thin paper ceramic layer 11, preferably only one of the metallizations or metal layer 2, 3 of the substrate 1 is patterned in order to ensure sufficient stability of the substrate 1. In the case of a corresponding, stability-enhancing intermediate layer, however, structuring of the two metallizations or metal layers 2, 3 of the substrate 1 is also possible.

This type of structuring is one of the subtractive methods in which a part of the metallization is removed or weakened in a wet-chemical process. In contrast, for the above-mentioned substrates 1, it is also possible to use additive processes such as galvanic deposition in order to increase the layer thickness of the metallization locally or over the entire surface. This can also be done, for example, by soldering moldings at defined points of the structured substrate. Also, a preparation of the substrates 1 according to the invention in the form of

Multiple substrates possible, which are isolated after the production of the desired substrates 1. The singulation takes place in the substrates 1 according to the invention, for example by means of mechanical processing operations such as, for example, sawing, cutting or punching or by using a laser unit or a water jet cutting edge. Accordingly, the extends

unstructured metal layer 7 different from the prior art preferably also up to the edge of the cutting edge of the respective substrate 1. In an alternative embodiment of the present invention improved substrates 10 according to Figure 2, the substrate 10 at least one composite layer 12 with a metal layer 13 and at least one aluminum layer 14, which is connected by means of an adhesive layer 6 with the paper-ceramic layer 11. The aluminum layer 14 of the composite layer 12 may be formed at least partially anodized, so that an anodized layer 15 is formed, which is connected via the adhesive layer 16 with the paper-ceramic layer 11. The anodizing layer 15 is provided as an adhesion promoter to replace the inherently smooth surface of the aluminum layer 14 with the roughened anodized layer 15, which ensures a high adhesive force of the adhesive bond between the paper-ceramic layer 11 and the composite layer 12. For this purpose, the anodized layer 15 has a layer thickness between 1 μνη

Also, by using a corresponding process temperature of 120 ° C up to 160 ° C, existing cracks and / or pore-shaped voids in the paper-ceramic layer 11 can be widened and then simply filled with the adhesive 6a ', 6b'. The temperature increase can be done stepwise or continuously over a given period of time. Advantageously, in the case of a step-like increase in temperature, evaporation of any solvent or thinner contained in the adhesive takes place. To improve the conductivity of the adhesives used, these can in one embodiment of the

Invention also be enriched with nanofibers. In a further embodiment variant, the respective adhesive layer 6 has at least two different adhesives, which are preferably applied in layers one behind the other. For example, adhesives

Different viscosities are used, wherein the one adhesive with lower viscosity for filling the pore-shaped cavities in the

Paper ceramic layer 11 and the other adhesive with high viscosity for

Preparation of the adhesive bond of the layer composite is provided.

It is understood that by means of the described method according to the invention, the production of substrates 1 with a wide variety of layer structures and in particular the construction of modules comprising a plurality of individual substrates 1 is possible.

In addition to the described two- or three-layer substrates 1, which are interconnected via corresponding adhesive compounds, and several layers of alternating metal layers and paper technology

prepared ceramic layers are provided. As a result, it is possible, for example, to provide interconnects located within the substrate 1 which are connected to electrical interconnections, so-called via's, to the external electrical circuitry of the substrate 1.

It is also possible to use multilayer composite layers 12 which have different metal layers and are connected to one another in a planar manner via further connection technologies known per se, such as, for example, a DCB or AMB connection.

Also, for example, a metal layer 2 and a paper-ceramic layer 11 having substrates 1 according to the invention can be glued, joined or soldered directly to a heat sink, using a

high-temperature-stable compound layer or a corresponding

Connection technology. In order to minimize the porosity of the paper-ceramic layer 1 1 prior to the manufacture of the substrate 1 according to the invention further pretreatments can be carried out, and this can still be done in the paper state and / or on the ceramic already produced.

In the paper state, the paper manufacturing process subsequent pressing, for example by means of calendering or a coating of the paper can contribute to a reduction of the pore-shaped cavities. To reduce the residual porosity, the already sintered paper-ceramic layer 11 can be coated, for example, on one or both sides, for example by means of sol-gel technology, dipping, spraying or brushing. Following this, however, re-sintering of the coated paper ceramic layer is required. Also, the pore-shaped cavities can at least partially be filled with similar or other ceramic materials, namely, for example by suspensions of fine ceramic powders or glass powder with grain sizes the deutl I caused lulosefasern by the Zel

Pore size> 5 vm l. Alternatively, materials such as

Water glass or organic, curable materials on.

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

LIST OF REFERENCE NUMBERS

1, 10 substrate

2 first metal layer or metallization layer

3 second metal layer or metallization layer

6, 6a, 6b adhesive layer

6a ', 6a ", 6b', 6b" adhesive or adhesive application

11 paper ceramic layer

12 composite layer

13 metal layer

14 aluminum layer

15 anodic layer d1 -d3 layer thicknesses

Claims

claims

1 . Substrate (1, 1 0) for electrical circuits comprising at least one

Metal lschicht (2, 3, 14) and one with the at least one metal lschicht (2, 3, 14) surface-connected paper ceramic layer (1 1) having a top and bottom (1 1 a, 1 1 b), wherein the paper ceramic layer (1 1) has a plurality of pore-shaped cavities, characterized in that the at least one metal lschicht (2, 3, 14) via at least one adhesive layer (6, 6 a, 6 b) with the paper ceramic layer (1 1) is connected through

Applying at least one adhesive (6a ', 6a ", 6b', 6b") to the

Metal lschicht (2, 3, 14) and / or on the paper ceramic layer (1 1) Hergestel lt, wherein by means of the applied adhesive (6a ', 6a ", 6b', 6b"), the pore-shaped cavities in the paper ceramic layer (1 1 ) are filled at least on the surface side.

2. Substrate according to claim 1, characterized in that the

Paper ceramic layer after filling with adhesive (6a ', 6a ", 6b', 6b") has a porosity below 1 0%, preferably below 5%.

3. Substrate according to claim 1 or 2, characterized in that the

at least one metal lschicht (14) with at least one further metal lschicht (1 3) to a composite layer (1 2) is connected.

4. Substrate according to one of claims 1 to 3, characterized in that the paper ceramic layer (1 1) has a layer thickness (d 1) between 50 μνη and 600; m, preferably 80 μνη and 1 50 μνη.

5. Substrate according to one of claims 1 to 4, characterized in that the paper-ceramic layer (1 1) has an E-modulus between 90 GPa and 1 50 GPa.

6. Substrate according to one of claims 1 to 5, characterized in that the paper ceramic layer (11) made of a sintered ceramic fillers enriched paper structure by means of thermal reaction, wherein the proportion of sinterable ceramic fillers of the enriched paper structure greater than 80 wt. %, preferably between 80 and 90 wt .-% is.

7. Substrate according to claim 6, characterized in that as a ceramic

Fillers of the paper structure AI203, Si3N4, AIN, ZrO2, MgO, SiC, BeO or a combination thereof and associated typical sintering aids, for example Y203, CaO, MgO, SiO2 are provided.

8. Substrate according to one of claims 1 to 7, characterized in that the paper ceramic layer (11) has a top and bottom (11a, 11b) and the top (11a) by means of an adhesive layer (6a) with a first

Metal layer (2) and the bottom (11 b) by means of another

Adhesive layer (6b) with a second metal layer (3) are connected flat.

9. Substrate according to one of claims 1 to 8, characterized in that the adhesive used for the preparation of the adhesive layer (6, 6a, 6b) (6a ', 6a ", 6b', 6b") has a viscosity less than 30 Pas.

10. Substrate according to one of claims 1 to 9, characterized in that the layer thickness (d3) of the adhesive layer (6, 6a, 6b) is between 1 and 30 vm, preferably between 1 and 10 μνη.

11. A substrate according to any one of claims 1 to 10, characterized in that the adhesive layer (6, 6a, 6b) is made of a chemically and / or physically curable adhesive from the group of polyurethanes, epoxy resins, polyimides or methyl methacrylate and / or that the

Adhesive layer (6, 6a, 6b) is made of at least two different adhesives with possibly a different viscosity.

12. Substrate according to one of claims 1 to 1 1, characterized in that the penetration depth of the adhesive (6a ', 6b') in the paper ceramic layer (1 1) at least one third of the adhesive layer (6a, 6b) subsequent layer thickness (d1 ) of the paper-ceramic layer (11).

1 3. A substrate according to any one of claims 1 to 1 1, characterized in that the pore-shaped cavities in the Papierkeramiksch light (1 1) almost vol lständig with adhesive (6a ', 6b') are filled.

14. Substrate according to one of the preceding claims, characterized

in that the at least one metal layer (2, 3, 13, 14) is made of copper, aluminum, gold, silver, tin, zinc, molybdenum, tungsten, Cr or alloys thereof.

1 5. A substrate according to any one of claims 3 to 14, characterized in that the composite layer (1 2) has a metal lschicht (1 3) and at least one aluminum layer or aluminum alloy layer (14).

1 6. A substrate according to claim 1 5, characterized in that the metal lschicht (1 3) as a copper layer or copper alloy layer (1 3) with a

Layer thickness between 35 μνη and 2 mm and the aluminum layer or aluminum alloy layer (14) has a layer thickness between 10 μνη and 300 jum.

1 7. Substrate according to claim 1 5 or 1 6, characterized in that the

Aluminum layer (14) of the composite layer (1 2) to produce a

Anodized layer (15) on the metal layer (13) opposite

Surface is anodized.

18. A method for the produc- tion of a substrate for electrical circuits

comprising at least one metal layer (2, 3, 1 3) and at least one paper ceramic layer (1 1) with a top and U nterseite (1 1 a, 1 1 b), in which at least the upper or lower side (11a, 11b) are connected in a planar manner to the at least one metal layer (13), the paper-ceramic layer (11) having a plurality of pore-shaped cavities, characterized in that the at least one metal layer (2, 3, 14) and / or on the top and / or bottom (11a, 11b) of the paper ceramic layer (11) adhesive (6a ', 6a ", 6b', 6b") for producing at least one adhesive layer (6, 6a, 6b) surface is applied, in such a way that by means of the applied adhesive (6a ', 6a ", 6b', 6b"), the pore-shaped cavities in the paper-ceramic layer (11) are filled at least on the surface side.

19. The method according to claim 18, characterized in that the adhesive (6a ", 6b") applied exclusively on the surface side of the at least one metal layer (2, 3) surface and then with the top or bottom (11a, 11b) of the paper-ceramic layer (11) is glued.

20. The method according to claim 18, characterized in that the adhesive (6a ', 6b') exclusively on the top and / or bottom (11a, 11b) of the

Paper ceramic layer (11) applied flat and then bonded to the at least one metal layer (2, 3).

21. The method according to claim 18, characterized in that the adhesive (6a ', 6a ", 6b', 6b") on both the surface side of the at least one

Metal layer (2, 3) and on the top and / or bottom (11a, 11b) of the paper-ceramic layer (11) applied flat and then both are glued together.

22. The method according to claim 21, characterized in that on the

at least one metal layer (2, 3) and the top and / or bottom (11 a, 11 b) of the paper-ceramic layer (11) at least two different

Adhesives are applied, the viscosity of the on the

Paper ceramic layer (11) applied adhesive (6a ', 6b') preferably is less than the viscosity of the metal on the lschicht (2, 3) applied adhesive (6a ", 6b").

23. The method according to claim 18, characterized in that ausschl ießl I on the top or U nterseite (1 1 a, 1 1 b) of the paper ceramic layer (1 1) surface adhesive (6a ', 6b') is applied, wherein the Adhesive amount is such that the pore-shaped cavities are almost vol lately filled.

24. The method according to any one of claims 1 8 to 23, characterized in that the amount of adhesive used is so eingestel lt, that in the connected state, an adhesive layer (6, 6a, 6b) with a layer thickness (d3) in the range between 1 and 30 μνη , preferably between 1 and 1 0 μνη arises.

25. The method according to any one of claims 1 to 8, characterized in that the pore-shaped cavities of the paper-ceramic layer (11) are filled with adhesive (6a ', 6a ", 6b', 6b") in such a way that the paper-ceramic layer (1 1) after the filling has a porosity of less than 10%, preferably less than 5%.

26. The method according to any one of claims 1 8 to 25, characterized in that by means of the applied adhesive (6a ', 6b'), the pore-shaped cavities along at least one third of the layer thickness (d 1) of the paper-ceramic layer 1 1 are filled.