WO2000028381A1

WO2000028381A1 - Method for producing microcomponents having flow channels

Info

Publication number: WO2000028381A1
Application number: PCT/DE1999/003286
Authority: WO
Inventors: Andreas Thies; Konrad CRÄMER; Heinrich Meyer
Original assignee: Atotech Deutschland Gmbh
Priority date: 1998-11-06
Filing date: 1999-10-07
Publication date: 2000-05-18
Also published as: AU1647600A

Abstract

The invention relates to method for producing microcomponents with flow channels in at least one plane, especially of chemical microreactors, heat exchangers, mixers and evaporators. The inventive method comprises the following steps: A. producing a first metal layer or metal film (1); B. coating at least one surface of the first metal layer or metal film (1) with a structured resist layer (3), whereby the first metal layer or metal film (1) has bare spots (6) which do not correspond to the channels to be produced; C. depositing a second metal layer (7) onto the bare spots (6) of the first metal layer or metal film (1); wherein the sequence of steps A to C is carried out several times to produce several planes and/or the sequence of steps A to C is followed by step A to produce a closing segment for the flow channels; and D. removing the resist layer (3) once the planes have been produced. The resist layer (3) can be a serigraphical coating layer, a photosensitive layer or a perforated film.

Description

Process for the production of micro components with flow channels

Description:

The invention relates to a method for producing microcomponents with

Flow channels in at least one level, in particular chemical microreactors, which can be used in the chemical industry, inter alia, for synthesis reactions and in other fields, for example as hydrogen sources for energy conversion (fuel cells), and also of heat exchangers, mixers and evaporators.

In the literature, chemical microreactors have been reported for some years, which have advantages over the conventional production plants for producing chemical compounds. This is an arrangement of reaction cells whose dimensions range from a few micrometers to a few millimeters and are therefore much smaller than those of conventional reactors. These reaction cells are designed so that physical, chemical or electrochemical reactions can take place in them. In contrast to a conventional porous system (heterogeneous catalysis), the dimensions of these cells are defined by the design, i.e. they can be produced according to plan using a technical process. The arrangement of individual reaction lines in the ensemble of the reactor is also ordered, in particular periodically in one, two or three dimensions. In the broader sense, chemical microreactors also include the necessary supply and discharge structures for the fluids (liquids, gases) as well as sensors and actuators, for example valves that control the flow of material through the individual cells, and heating elements.

The use of chemical microreactors as hydrogen sources for fuel cells for energy conversion is described, for example, by R.Peters et al. in "Scoutiπg Study about the Use of Microreactors for Gas Supply in a PEM- Fuel Cell System for Traction", Proc. of the 1 ^st Int. Conf. on Microreaction Technology, Frankfurt, 1997.

This concept for chemical microreactors has also been applied to heat exchangers. In this case, there are at least two separate fluid channels in the heat exchanger, which are used to transfer heat from fluid in one channel to fluid in the other channel.

There are a number of proposals for the production of chemical microreactors or heat exchangers:

For example, a chemical microreactor can be produced by stacking a plurality of copper foils into which grooves are carved using a diamond tool to form flow channels. Such a production process is described by D.Hönicke and G.Wiesmeier in "Heterogeneous Catalyzed Reactions in a Microreactor" in DECHEMA Monographs. Volume 132, Papers of the Workshop on Microsystem Technology, Mainz, 20 to 21 February 1995, pages 93 to 107. For the production of acrolein from propene, the inner walls of the reaction channels were partially oxidized to copper (l) oxide.

The LIGA process (lithography, electroforming, molding) exposes a plastic layer, usually polymethyl methacrylate (PMMA), using synchrotron radiation and then develops it. The structure produced in this way is filled with metal using an electrolytic process. The metal structure can then be reproduced in further process steps by means of a plastic impression (plastic injection molding process). This method was developed by W. Ehrfeld and H. Lehr in Radial Phys. Chem. Volume 45. Pages 349 to 365.

A technique related to the LIGA process that does not require the very complex synchrotron radiation is the so-called laser LIGA process. The PMMA plastic layer is structured with a powerful UV laser and then galvanically molded as in the LIGA process (W. Ehrfeld et al., "Potentials and Reaction of Microreactors" in DECHEMA Monographs, Volume 132, pages 1 to 29).

The methods that have been developed in the semiconductor industry for structuring silicon surfaces have also been adopted for the production of microreactors. For example, J.J.Lerou et al. in "Microfabricated Minichemical Systems: Technical Feasibility", DECHEMA Monographs, Volume 132, pages 51 to 69, describes a process in which three etched silicon wafers and two end wafers were connected to one another on the outer sides. Furthermore, a heat exchanger filled with polycrystalline silver particles, which was also designed as a microreactor, was used.

EP 0 212878 A1 describes a method for producing a heat exchanger in which the flow channels of the heat medium are formed in steel plates by chemical etching. The steel plates are then welded to one another by diffusion bonds.

WO 9215408 A1 describes a method for producing microsieves, in which holes and other depressions are etched with a specific pattern by plasma technology in a flat carrier covered with an etch-resistant layer. Several of these perforated beams are then connected together.

DE 197 08 472 A1 describes a production process for chemical microreactors in which fluid channels are formed in individual planes by structuring substrates provided with metal surfaces by means of photolithographic techniques or screen printing processes and the resulting channel structures being formed by metal removal or application processes. The individually produced levels are then combined into a stack and firmly connected. For example, the channels can be produced by partially etching away the metal layer on the substrate. The previously known methods for producing chemical microreactors and heat exchangers have many disadvantages. For example, complicated and / or expensive techniques for making the channels are required. In some cases, the manufacture of the reactors is limited only to silicon as the material.

It is also disadvantageous in particular that certain sensitive functional surface layers for specific applications in chemical reaction technology can be destroyed or at least damaged when the individual planes are joined, especially if a high temperature is used in the joining process. As a possible remedy, it was also proposed to bond the individual layers to one another by gluing. However, this technique has limits and risks in that the adhesive gets into and clogs the fine channels and / or that the adhesive bond is not strong enough under the operating conditions to withstand the generally high pressure that the fluids pass through withstand the reactor or heat exchanger. In addition, because of their generally low heat and chemical resistance, adhesives are only suitable for producing the microreactors in special cases

In chemical reaction technology, the functional surface layers are used, for example, to catalyze chemical reactions. A subsequent coating of the flow channels in the levels is often not possible, since in this case the functional layers themselves cannot be applied electronically due to the fresh shielding by the reactor or heat exchanger itself. Even with electroless metallization, it has been found that a safe coating is not possible. since the metallization baths usually used react very sensitively to different flow rates of the metallization liquid on the surfaces to be coated. Under these conditions, surface areas, among other things, are electrolessly metallized, which the metallizing liquid slowly flows past, during surface areas. past which the liquid flows at high speed, are not coated with metals. Another disadvantage of the known processes is that, in practice, considerable difficulties have to be overcome when assembling the stacked reactors and occur when the microcomponents are encased. These difficulties are due to leaks during joining and to material distortion under thermal loads. The more joining seams a component has, the higher the risk of leaks, so that a high scrap in the manufacture of the reactors must generally be expected if this technique is used.

The present invention is therefore based on the problem of microcomponents with flow channels in at least one plane, in particular chemical microreactors. Manufacture heat exchangers, mixers and evaporators that are suitable for a large number of different applications in chemical reaction technology, for heat exchange, for mixing substances or for evaporating liquids. In particular, it should be possible to apply different coatings to the channel surfaces for different applications of the microcomponent. Furthermore, the manufacturing process should be as inexpensive and quick to carry out without high failure rates in the manufacture of the microcomponents. Such microreactors, heat exchangers, mixers and evaporators should be easy and inexpensive to produce even in large numbers.

This problem is solved by the method according to claim 1. Preferred embodiments of the invention are specified in the subclaims.

The method according to the invention is used to manufacture microcomponents with flow channels in at least one level, in particular chemical microreactors. Heat exchangers. Mixers and evaporators. The flow channels preferably have dimensions from a few micrometers to a few millimeters.

The chemical microreactors are preferably used in the chemical industry, inter alia, for synthesis reactions and in other fields, used for example as hydrogen sources for energy conversion (fuel cells).

Chemical microreactors are understood to be devices with flow channels in at least one reactor position which, in addition to the actual reaction zones, may also have auxiliary zones which are used for mixing, metering, heating, cooling or analyzing the starting materials, intermediate products or end products. Each zone is characterized by a structure that is adapted to the respective requirements. While heating and cooling zones are designed either as heat exchangers or as reactor abbeys equipped with electrical resistance heaters or electrical cooling elements, analysis zones have adapted sensors. Dosing zones contain, for example, microvalves and mixing zones, for example channels with suitably shaped internals for swirling the combined fluids.

Flow channels are contained in at least one level in the microreactors, heat exchangers, mixers and evaporators. The flow channels in the individual levels can also be partially connected to one another.

For the following explanation of the method, reference is made to FIGS. 1 and 2. Show it:

1: shows a schematic representation of the sequence for the manufacturing method in a first embodiment;

2: a schematic representation of the sequence for the manufacturing process in a second embodiment.

In the first embodiment of the invention (FIG. 1), a first metal layer 1 is first produced to produce the multilayer microcomponents (method step A). This metal layer can be formed using a galvanotechnical or physical metal deposition process either on a carrier 2, for example on an artificial peat plate or a metal plate, or a self-supporting foil can be produced. Such films are known from printed circuit board technology. All conventional vacuum processes can be used for coating with a physical metal deposition process, namely the CVD (chemical vapor deposition), PECVD (chemical enhanced vapor deposition), vapor deposition and sputtering processes. This metal layer is preferably formed by electrolytic metal deposition. It usually consists of copper, nickel, cobalt, zinc, tin, chromium, iron (steel, stainless steel), aluminum or alloys of these metals with one another or with other elements, for example phosphorus or boron. In principle, however, it can also consist of another metal. For electrolytic metal deposition, in which an external power source is required for metal deposition, the deposition of an electrically conductive starting layer is first necessary. This can be formed, for example, by electroless metal deposition after prior activation of the non-catalytic surface with palladium seeds. The thickness of the metal layer 1 is preferably at least 0.1 μm in order to ensure sufficient electrical conductivity for subsequent manufacturing steps. A thickness of 5 μm to 1 mm is common.

The first metal layer or metal foil is then coated in a first process variant on at least one of the two surfaces with a photosensitive layer 3 (process step B). The thickness of this layer is determined by the height of the flow channels to be formed later. Usually, positive or known from the printed circuit board technology, the microsystem technology and from the chip manufacturing techniques

Negative photoresists used. After drying, the photosensitive layer formed is exposed to the pattern of the channels, for example through a mask 4 (light rays 5; method step B1) and the underlying metal layer or metal foil 1 is subsequently exposed in the development process at all locations 6 which do not correspond to the channels to be formed (Process step B2). In another variant (not shown in FIG. 1), at least one surface of the first metal layer or metal foil 1 is coated with a screen printing lacquer layer at the locations on the surface which correspond to the channels to be formed.

In a third method variant, a foil, preferably a plastic foil, is laminated onto at least one surface of the first metal layer or metal foil 1, the foil being provided with perforations at all points 6 of the surface which do not correspond to the channels to be formed. The use of such a film is advantageous when particularly high

Flow channels are to be formed so that the resist structure must be very thick. Therefore, foils with a thickness of 50 μm and more are used.

Both when coating with a photosensitive resist and subsequently exposing and developing the resist and when coating with a screen printing lacquer layer or a perforated film, a structure is obtained in which the first metal layer or metal foil is covered with the resist or the foil at all points which correspond to the flow channels to be formed.

A second metal layer 7 is then deposited at the exposed or exposed locations 6 of the first metal layer or metal foil 1 (method step C1). Typically, an electroplating process is used for this, preferably an electrolytic metal deposition process in which an external power source is used for metal deposition. Of course, the second metal layer can also be produced by electroless metallization. If a selective deposition of the second metal layer is desired only at the exposed or exposed locations 6 of the first metal layer or metal foil 1, but not on the screen printing lacquer layer, the photosensitive layer or the perforated film 3, then this must be taken care of separately when using the currentless method that the second metal layer 7 only on the first metal layer or the metal foil is formed, for example by applying a negative electrical potential to the first metal layer or the metal foil during the deposition of the second metal. If, on the other hand, an electrostatic metal deposition process is selected, this metal is automatically and selectively deposited only on the exposed areas of the first metal layer or metal foil. The metal of the second metal layer can be identical to the metal of the first metal layer or metal foil. Another metal can also be applied to form the second metal layer. In the finished microreactor, heat exchanger, mixer or evaporator, the second metal layer forms the walls of the flow channels. This metal layer must therefore have a thickness which corresponds to the height of the flow channels. The second metal layer should preferably be as thick as the screen printing lacquer layer, the photosensitive layer or the perforated film.

Before the formation of further channel levels or a termination segment for

Closing the flow channels, the first channel level formed can - if necessary - be leveled by a mechanical or other surface treatment, for example by micro milling or polishing.

The process sequence A to C described above is carried out several times in succession to form the second and further channel levels. This means that, in a method step A ', a further first metal layer 1' is then applied to the surface of the photoresist layer. Screen printing resist layer or on the perforated film 3 and on the second metal layer 7 is applied. This further first metal layer V, like the corresponding metal layer or metal foil 1 in the first level, represents a base layer on which the individual flow channels of the next channel level are formed. To produce this base metal layer in the second level, as well as for forming the first metal layer or metal foil 1 a thin conductive starting layer made of metal is first deposited in the first channel level if this first metal layer is deposited electrolytically. If this starting layer is formed by an electroless path, a catalytic layer for electroless metal deposition must first be removed. be divorced. Palladium colloids, for example, are suitable for this. These are used to prepare the electrically non-conductive surfaces for the deposition of the thin conductive starting layer, which can form the basis for an electrolytically deposited metal layer. The second base layer can also be formed using a physical metal deposition process, for example by sputtering.

After the formation of this second base layer 1 ', a photosensitive layer, a structured screen printing lacquer layer or perforated film is again applied. The photosensitive layer, screen printing lacquer layer or perforated film is then dried. The photosensitive layer is then exposed to the image of the flow channels and developed. The screen printing lacquer or foil structure also has the image of the flow channels. The second metal is then again formed on the exposed metal surfaces. Then further levels are applied in the manner described.

After the completion of the individual levels, the top reactor or heat exchanger level is covered by a last metal layer to close the top channel level. This metal layer is also called the end segment. Finally, front plates can optionally be provided on the two end faces of the reactor, heat exchanger, mixer or evaporator, which are screwed together, for example, in order to absorb the forces occurring during the flow.

If a microcomponent is produced with only one flow channel level, then following the above-mentioned method sequence with steps A to C, with which a flow channel level is formed, method step A is carried out to form an end segment for the flow channels. In this case, the metal layer 1 'applied after the formation of the first channel level represents the end segment. After the completion of the microcomponent with one or more flow channel levels, the photoresist, screen printing resist or the perforated film is removed from the flow channels which are kept free during the metallization.

In contrast to the known methods, the individual micro component levels are thus produced in a sequential manner with the method according to the invention. This eliminates the disadvantage that the individual levels must be connected to one another and to the end segment in a joining process after their separate production. On the other hand, no leaks can occur in the finished micro-component due to an inadequate joining process. In addition, basically all metals that can be deposited by means of electroplating processes can be used as materials. For example, copper, nickel, cobalt, zinc, tin, chromium and iron and their alloys can be used to manufacture the flow channel walls. Precious metals such as platinum, gold, silver, ruthenium and palladium are particularly suitable for the functional layers. When using the known manufacturing processes, the individual layers initially produced separately are subsequently connected to one another by diffusion welding or soldering. However, this presupposes that materials are also used that can be diffusion welded or soldered. In addition, in contrast to the components produced by the known methods, there is no material distortion during the production of the microcomponents according to the invention. Such a disadvantageous effect can usually not be avoided when joining the conventional microcomponents due to the large amount of heat. Another advantage of the method according to the invention is that no special measures have to be taken to ensure good adhesion between the second and further base layers V (or 1 ", V", ...) and the photoresist layer, screen printing resist layer or the perforated foil.

It is also advantageous that functional levels are created in the course of the formation of the individual levels. for example, catalytic layers can be applied to the flow channel walls. The functional layers could in principle also be produced after the production of the micro component. in the In the case of the joined components, however, the soldered connections between the individual channel levels interfere, since these can deactivate the electroless plating baths for producing the functional layers. In addition, a metallization process using an external power source cannot be used to apply these layers after the reactor is completed.

To carry out the functional layers, after performing step C1 in an additional step C2 (FIG. 1), a third metal layer 8 is produced by electrolytic or electroless metal deposition or by a physical metal deposition method, for example a sputtering, vapor deposition, CVD or PECVD method , educated. Alternatively, molecular layers which have specific catalytic properties can also be chemisorbed or adsorbed, or plastic or ceramic layers can also be formed. The ceramic layers are particularly advantageous when a large surface is to be created on the flow channel walls. Porous ceramic layers are formed for this purpose, for example oxide layers by sputtering. A vapor-deposited aluminum layer is also particularly suitable and can subsequently be converted into an aluminum oxide layer by anodizing or treatment, for example with nitric acid. Such a layer can serve as a support for catalysts with which this layer can be impregnated.

Layer 8 in turn can also be made up of different layers. These layers can also serve as supported catalysts. For this purpose, the surfaces of the screen printing lacquer layer, the photosensitive layer or the perforated film and the second metal layer are first cleaned. The cleaned surfaces can then be brought into contact with an activation solution, for example a palladium koiloid solution, which has a catalytic effect for the subsequent electroless metal deposition in order to be able to electrolessly deposit metal on the non-catalytic surfaces of the screen printing lacquer layer, photosensitive layer or the perforated film. Layer 8 can also be selectively applied exclusively to the screen printing Layer, the photosensitive layer or the perforated film are applied by suitable mask processes, in order to prevent layers 8 deposited on the metal layer 7 from impairing the adhesive strength of metal layers subsequently applied to the layer 7.

Activation solutions of this type are known per se. These are usually formed by mixing palladium chloride, tin (II) chloride and hydrochloric acid or palladium sulfate, an aminopyridine and lye or palladium sulfate, an organic protective colloid such as polyvinylpyrrolidone and sodium hypophosphite. The activated surfaces are then brought into contact with a metallization solution, for example an acidic solution containing palladium ions. A palladium plating solution which can be used well for this purpose additionally contains an oxidizing agent, for example sodium peroxodisulfate. Alternatively, for example, a corrosion protection layer made of a nickel / phosphorus alloy can also be deposited. Commercial baths are available for this purpose which contain a nickel salt as well as carboxylic acids as complexing agents for nickel ions and sodium hypophosphite as reducing agent.

In a further process variant (FIG. 2), the second metal layer 7 is modified in a modification of the previously described method in a reactor, heat exchanger, mixer or evaporator level in accordance with method step C and the first metal layer V in the subsequent level or as the final segment serving first metal layer V according to process step A 'in a single combined process step. This eliminates a separate process step. The metals of the first and second metal layers are preferably identical.

The formation of the combined layer 7.1 'according to the process section C + A', which at the same time represents the base layer for the next channel plane, is followed by the process described above for the formation of the next level. Then the surface is first structured using a screen printing varnish, a photosensitive layer or a perforated film. nert and then another metal layer applied according to process steps C and A '. The reference numerals given in FIG. 2 otherwise correspond to those in FIG. 1

In this case too, the metal layer V serves as an end segment, the formation of which is not followed by any further process steps if only one flow channel level is to be formed.

Functional layers 8 are also deposited in the production of microcomponents according to this process scheme. These are applied to the resist surfaces (process section B3 in FIG. 2). For this purpose, the same process techniques are used as in the process variant according to FIG. 1 described first.

Furthermore, further metal layers can be deposited, provided that specific requirements of the respective application require it. For example, particularly wear-resistant layers against corrosion and abrasion, for example made of chromium, a nickel / phosphorus alloy or palladium, can be deposited, or surfaces made of catalytically active metal (platinum, palladium) can be formed electrolytically or without current. Magnetic rails, for example made of a ferromagnetic nickel / cobalt alloy, may also be necessary for certain applications, such as for example the use of solenoid valves as actuators. Furthermore, the surface structure can also be roughened or smoothed by chemical or electrolytic etching techniques

After the desired number of channel levels has been formed, the screen printing lacquer layer. Photosensitive layer or perforated film removed in a further process step D For this purpose, the structure produced can, for example, be brought into contact with a solvent for the screen printing lacquer layer, the photosensitive layer or the perforated film with the simultaneous action of ultrasound and heat low surface tension The choice of solvent depends on the type of plastic material to be dissolved (screen printing varnish, photosensitive layer, perforated film). Acetone, chloroform, butanone, 1, 4-dioxane and N, N-dimethylformamide and their mixtures and for photoresists N-methylpyrrolidone, trichloroethane, dimethyl sulfoxide and methylene chloride and their mixtures are, for example, suitable for polymethyimethacrylate as plastic material. In addition, aqueous alkaline systems with suitable cosolvents can be used.

Alternatively, the screen printing lacquer layer, photosensitive layer or perforated film can also be removed by pyrolysis. For this, the educated

Microcomponent structure transferred into an oven and the screen printing varnish, the photosensitive layer or the perforated film thermally decomposed. Any residues of the decomposed organic material can then be removed in a solvent, again preferably under the influence of ultrasound and in the presence of a suitable wetting agent.

In a further process variant, the plastic can also be removed using a plasma process. For this purpose, the finished micro component structure is brought into a glow discharge zone of a plasma reactor.

In a still further process alternative, the screen printing lacquer layer, photosensitive layer or perforated film can be removed in accordance with process step D using supercritical liquids. For this purpose, the micro-component structure is brought into contact with carbon dioxide, ethylene, propane, ammonia, nitrous oxide, water, toluene, nitrogen heterocycles or other substances which are in a supercritical state under suitable pressure and temperature conditions, for example in an autoclave. Supercritical fluids that can be converted into the supercritical state at room temperature are particularly suitable. A well suited supercritical fluid is carbon dioxide. The suitable conditions for this are T = 40 ° C and P = 80-10 ³ to 200-10 ³ hPa (_> 80 to 200 bar). After completion of the reactor, heat exchanger, mixer or evaporator structure, the required fluid connections to external components, such as pumps and tanks, are formed.

To further explain the invention, micro component levels are shown as examples. Show it:

3 shows a schematic illustration of a cross section through a heat exchanger; Fig. 4: a schematic representation of a cross section of several channel levels in a multiple use for six continuous reactors.

3 shows a channel layer 10 in a heat exchanger. This single layer consists of two superimposed metallic layers

(dark area) on respective documents (boundaries indicated by dash-dotted lines), which were produced according to one of the methods described above. For example, these two metallic layers can have been produced on the substrate by electrolytic deposition of copper in accordance with process steps A to C. Several of these layers form a heat exchanger.

In the layer 10 there are channels 11 through which a fluid (liquid or gas) is passed during the operation of the heat exchanger. In the present case, the channels are produced by a photolithographic process. These channels extend in the upper of the two layers and have a width of approximately 400 μm and a height of approximately 100 μm. The channels 11 end in connection spaces π 12 ', 12 "', which are used to connect the chemical micro-reactor to corresponding feed and discharge lines for the fluid to be passed through. The fluid flowing through the heat exchanger can be operated, for example, via the connection space shown in FIG. 3 above 12 'are passed into the channels 11 and, after passing through the channels, leave the microreactor again through the connection space 12'"shown in FIG. 3 below. Several layers of the type shown lie one above the other in the heat exchanger. The layers above and below the layer shown have channels which are rotated by 90 ° with respect to the channels of the layer shown. This results in a stacking sequence ... ABABAB ..., where A means the layers with the orientation shown and B the adjacent layers with orientation rotated by 90 °. As a result, on the one hand the connection spaces 12 'and 12'"of the layers with the designation A lie one above the other and on the other hand the connection spaces 12" and 12 "" of the layers with the designation B one above the other. The channels in the layers with the designation A are connected to one another via the respective connection spaces. The same applies to the

Channels in the position designated B. There is no fluid connection between the flow channels in the two layer types A and B. This makes it possible to pass two fluids independently of one another through the heat exchanger, for example a hot and a cold liquid. In operation, the hot liquid in the heat exchanger is cooled by the cold one and the cold liquid is warmed up by the hot one.

Screw connections are provided, for example, for the gas and liquid-tight connection of the connection spaces 12 \ 12 ", 12" ', 12 "" with corresponding supply and discharge lines. That limit the connection spaces

Channel plane areas 13 serve as sockets for the screw connections and are processed so that circular projections with external threads are formed from the respective end face of the reactor, so that supply and discharge pipes can be connected to these sockets, for example with union nuts, in a gas-tight and liquid-tight manner. The supply and discharge lines are connected to the connection spaces 12 ', 12 ", 12" \ 12 "" which are open to the outside. Of course, the connections to the supply and discharge pipes can also be made by welded or soldered connections. In this case, however, it must again be taken into account that, when joining, heat-sensitive functional layers in the heat exchanger channels could be damaged or even destroyed. Therefore, a mechanical method of making the connections is preferable. A micro component according to the invention typically has outer side lengths which are in the range from one to a few centimeters. The connection spaces 12 ', 12 ", 12"', 12 "" of the layer 10 shown in FIG. 3 in the present case have side lengths of 1 cm each.

Of course, the layers can also have channels with a different shape, for example for systems based on the countercurrent principle, as well as openings to neighboring layers. Breakthroughs can be formed by appropriately depositing metal when forming the first and second metal layers. The openings can also be produced by chemical or electrochemical etching of the first and second metal layers formed.

Further functions can also be provided on the metallic layer of a layer 10. On the one hand, so-called actuators and sensors can be integrated into a microreactor. The actuators are switching elements that can be controlled externally or automatically by means of measurement signals, for example valves, but also electrical resistance heaters or cooling elements that function according to the Peltier effect. Microreactors, in which actuators and sensors are provided, can be locally optimized if the actuators and sensors are linked appropriately in terms of control technology. At the same time, the sensor outputs can be used for external monitoring of the reactor condition (such as aging, poisoning of catalysts and similar parameters).

For the actuators and sensors, electrical connection lines for controlling or for recording measurement signals on the substrates may also have to be provided. Suitable structuring elements for these elements must be taken into account in the photo process.

Microchips for controlling actuators and sensors can also be integrated into the interior of microreactors, for example, by electrically isolating the microchips from the metallic layers. For this, the Chips are placed, for example, on the screen printing lacquer layer, photosensitive layer or perforated film. The electrical connections to corresponding control and signal lines can be made by bonded wires or other known connection techniques, such as by soldering or gluing.

In addition to the actual reaction cells, peripheral reactor components such as feed lines, mixing zones, heating or cooling circuits can also be formed at the same time as the structures are being formed, so that the production outlay is reduced. Therefore, these elements must already be provided when structuring the photo. In addition, the usual sealing problems are minimized.

4 shows an ensemble of six channel levels for several flow reactors in a multiple use. The benefit receives so-called tooiing holes 15 near the corners, which are used for the precise alignment of masks to produce structures in successive layers.

The layers shown here differ from the channel position in FIG. 3 in that only recesses for connection spaces 12 ^, _> 12 '"are provided on two mutually opposite sides of the layers, while in the case of the position of FIG. 3 it is also rotated by 90 ° arranged recesses are available.

In order to make the manufacture of the reactors particularly economical, the individual elements of the reactors are in this case produced in a multiple use at the same time. The individual reactors are then separated from one another along the dashed lines 14.

Claims

Claims:

1. Method for producing microcomponents with flow channels in at least one level, in particular chemical microreactors, heat exchangers, mixers and evaporators, with the following method steps:

A. Making a first metal layer or metal foil;

B. coating at least one surface of the first metal layer or metal foil with a photosensitive layer, exposing the photosensitive layer to the pattern of the channels and exposing the first metal layer or metal foil at all locations which do not correspond to the channels to be formed; or

Coating at least one surface of the first metal layer or metal foil with a screen printing lacquer layer at the locations on the surface which correspond to the channels to be formed; or

Laminating a perforated foil onto at least one surface of the first metal layer or metal foil, the perforations of the foil being provided at all locations on the surface which do not correspond to the channels to be formed; C. depositing a second metal layer at the exposed or exposed locations of the first metal layer or metal foil,

characterized in that process sequence A to C for forming the multiple levels is carried out several times in succession and / or process sequence A to C is followed by process step A for forming an end segment for the flow channels and D. that the screen printing lacquer layer. the photosensitive layer or the perforated film is only removed after the layers have been formed.

2. The method according to claim 1, characterized in that on the first metal layer or the metal foil and the screen printing lacquer layer, photosensitive layer or perforated film after performing step B or on the second metal layer and on the screen printing lacquer layer, photosensitive layer or perforated film after Carrying out process step C a third metal layer, a molecular layer, a plastic layer or a ceramic layer is formed.

3. The method according to claim 1, characterized in that the second metal layer is formed in one level according to method step C and the first metal layer in the subsequent level according to method step A in a single method step, the metals of the first metal layer and the second metal layer are identical.

4. The method according to claim 3, characterized in that between the method step B and the method step C, a third metal layer, a Moiekülschicht, a plastic layer or a ceramic layer is applied to the screen printing lacquer layer, photosensitive layer or perforated film.

5. The method according to any one of the preceding claims, characterized in that the screen printing lacquer layer, photosensitive layer or perforated film according to process step D is removed with a solvent under the action of ultrasound.

6. The method according to any one of claims 1 to 4, characterized in that the screen printing lacquer layer, photosensitive layer or perforated film is removed according to process step D by pyrolysis.

7. The method according to any one of claims 1 to 4, characterized in that the screen printing lacquer layer, photosensitive layer or perforated film according to step D is removed by a plasma process.

8. The method according to any one of claims 1 to 4, characterized in that the screen printing lacquer layer, photosensitive layer or perforated film is removed in accordance with process step D with supercritical liquids.

9. The method according to any one of the preceding claims, characterized in that the first metal layer or the metal foil and the second metal layer are formed by electrolytic metal deposition.