DE102012222416A1 - Method for joining at least two components using a sintering process - Google Patents

Abstract

The present invention relates to a method for joining at least two components (18, 20) using a sintering process. In order to improve the sintering process, the method comprises the method steps: a) Providing a starting material (10) of a sintered compound (22), comprising sinterable particles (12), comprising at least one metal or at least one metal compound, and at least one polymeric, polymerizable and / or monomeric organic compound (14), wherein the polymeric, polymerizable and / or monomeric organic compound (14) has a flow temperature that is greater than or equal to room temperature and less than the sintering temperature, and wherein the polymeric, polymerizable and / or monomeric organic Compound (14) also has a desorption temperature which is greater than the flow temperature and less than or equal to the sintering temperature; b) arranging the starting material (10) between two components (18, 20) to be connected; c) heating the starting material (10) to a temperature T1 which is greater than or equal to the flow temperature of the polymeric, polymerizable and / or monomeric organic compound (14) and less than the desorption temperature of the polymeric, polymerizable and / or monomeric organic compound (14) is for a time t1; and d) heating the starting material (10) to a temperature T2 which is greater than or equal to the sintering temperature of the sinterable particles (12), optionally under the action of a sintering pressure, for a period of time t2 with the formation of a sintered connection (22).

Description

The present invention relates to a method of joining at least two components using a sintering process.

State of the art

Power electronics are used in many areas of technology. Especially in electrical or electronic devices in which large currents flow, the use of power electronics is unavoidable. The currents required in the power electronics lead to a self-heating of the electrical or electronic components contained. In addition, the components of the power electronics can be used in places that are constantly exposed to an elevated temperature. Examples include control devices in the automotive sector, which are arranged directly in the engine compartment or in the gear compartment. In this case, the control unit is also exposed to a constant temperature change, whereby the electrical and / or electronic components contained are subjected to high thermal loads. In general, temperature changes in a range up to a temperature of 200 ° C are common. However, more and more operating temperatures are increasingly required. As a result, overall increased demands are placed on the reliability and reliability of electrical or electronic devices with power electronics.

Usually, a connection of electrical or electronic components - for example, to a carrier substrate - by a connecting layer. As such a bonding layer solder joints are known, for example, lead-free solder joints of tin-silver or tin-silver-copper. At higher operating temperatures, lead-containing soldered joints can be used. However, lead-containing solder joints are severely limited by legal regulations for reasons of environmental protection in terms of their permissible technical applications. Alternatively, lead-free brazing alloys are suitable for use at elevated or high temperatures, in particular above 200 ° C. Lead-free brazing alloys generally have a higher melting point than 200 ° C.

Also used are sintered connections, which can be processed at low temperatures and yet are suitable for operation at elevated temperatures. Such sintered connections offer the advantage of an increased choice of electrical or electronic components, which come as a joining partner due to the lower processing temperature. Another advantage of sintered connections is that there is no creep of the connecting layer and thus no formation of cracks, as a result of which a failure of an assembly having such a connection can be further reduced.

So shows the patent application DE 10 2007 046 901 A1 such sintered compounds. To produce a sintered compound, a paste-like starting material comprising readily decomposable silver compounds and silver flakes or nanosilver is used. Furthermore, copper may be contained in the starting material, for example.

The document EP 2 278 593 A1 discloses a sintered compound made from a paste containing particles of a silver compound.

From the document US 2008/0211095 A1 Furthermore, a semiconductor device is described, which has a connection between a semiconductor element and an electrode, which is designed by an electrically conductive adhesive.

The document US Pat. No. 6,832,915 B2 further discloses a thermally conductive adhesive bond between two components.

From the document DE 10 2007 27 999 A1 Further, a transfer film for transferring a silver sintered layer is known.

From the document DE 10 2004 019 567 B3 Furthermore, a method for mounting electronic components is described, in which the components are mounted on a substrate by means of pressure sintering using a pasty layer.

From the document JP 63258084 A Furthermore, a carrier film with a sintering paste for joining electronic components is known.

The US 6,951,666 shows the production of different sintered connections. In this case, general combinations of different output elements are described. As starting elements, among others, molecular metals, numerous nano- or micro-sized metallic particles, coatings, solvents, additives, reducing agents, crystallization inhibitors, wetting agents and others are mentioned.

Disclosure of the invention

• a) Bereitstellen eines Ausgangswerkstoffs einer Sinterverbindung, umfassend sinterbare Partikel, aufweisend mindestens ein Metall oder mindestens eine Metallverbindung, und mindestens eine polymere, polymerisierbare und/oder monomere organische Verbindung, wobei die polymere, polymerisierbare und/oder monomere organische Verbindung eine Fließtemperatur aufweist, die größer oder gleich der Raumtemperatur und kleiner als die Sintertemperatur ist, und wobei die polymere, polymerisierbare und/oder monomere organische Verbindung ferner eine Desorptionstemperatur aufweist, die größer als die Fließtemperatur und kleiner oder gleich der Sintertemperatur ist;
• b) Anordnen des Ausgangswerkstoffs zwischen zwei zu verbindenden Komponenten;
• c) Erwärmen des Ausgangswerkstoffs auf eine Temperatur T1, die größer oder gleich der Fließtemperatur der polymeren, polymerisierbaren und/oder monomeren organischen Verbindung und kleiner als die Desorptionstemperatur der polymeren, polymerisierbaren und/oder monomeren organischen Verbindung ist für eine Zeit t1; und
• d) Erwärmen des Ausgangswerkstoffs auf eine Temperatur T2, die größer oder gleich der Sintertemperatur der sinterbaren Partikel ist, gegebenenfalls unter Einwirkung eines Sinterdrucks, für eine Zeitdauer t2 unter Ausbildung einer Sinterverbindung.

The subject matter of the present invention is a method for joining at least two components using a sintering process, comprising the method steps:

• a) providing a starting material of a sintered compound, comprising sinterable particles, comprising at least one metal or at least one metal compound, and at least one polymeric, polymerizable and / or monomeric organic compound, wherein the polymeric, polymerizable and / or monomeric organic compound has a flow temperature, the is greater than or equal to room temperature and less than the sintering temperature, and wherein the polymeric, polymerizable and / or monomeric organic compound further has a desorption temperature greater than the flow temperature and less than or equal to the sintering temperature;
• b) arranging the starting material between two components to be connected;
• c) heating the starting material to a temperature T1 which is greater than or equal to the flow temperature of the polymeric, polymerizable and / or monomeric organic compound and less than the desorption temperature of the polymeric, polymerizable and / or monomeric organic compound for a time t1; and
• d) heating the starting material to a temperature T2 which is greater than or equal to the sintering temperature of the sinterable particles, optionally under the effect of a sintering pressure, for a period t2 to form a sintered compound.

The above-described method can in particular make it possible to carry out a sintering process in a particularly simple manner and thereby to produce a particularly stable and reliable sintered connection.

For this purpose, in the method described above according to a method step a) provides a starting material of a sintered compound, comprising sinterable particles, comprising at least one metal or at least one metal compound, and at least one polymeric, polymerizable and / or monomeric organic compound, wherein the polymeric, polymerizable and or monomeric organic compound has a flow temperature greater than or equal to room temperature and less than the sintering temperature, and wherein the polymeric, polymerizable and / or monomeric organic compound further has a desorption temperature greater than the flow temperature and less than or equal to the sintering temperature is.

Thus, according to method step a), initially a starting material is provided which is intended to form the sintered connection in the further method. The starting material in this case comprises a background material, which after sintering may represent the actual sintered connection or at least forms a large proportion of the sintered connection. This background material may in particular be at least one metal or at least one metal compound. Furthermore, the starting material has at least one polymeric, polymerizable and / or monomeric organic compound. The polymeric, polymerizable and / or monomeric organic compound can serve to hold the backing material together and thus allow the starting material to be provided as a compact, for example moldable, for example, thermoplastic, shaped article, for example.

By a polymeric organic compound, by way of example and not by way of limitation, a hydrocarbon-based compound which is polymerized can be considered. Accordingly, a polymerisable organic compound may be understood as meaning, for example and not by way of limitation, such a particular hydrocarbon-based compound which may be subjected to polymerization, in particular by having specific functional groups. An organic monomeric compound may further be understood as meaning, for example and not by way of limitation, such a compound which may also be hydrocarbon-based but need not have any groups suitable for polymerization.

By providing such a starting material of a sintered compound, the starting material can be provided as a transportable and storable material which can be applied at any time and without any special effort. In other words, the starting material may be produced in advance and stored and fed to its use immediately prior to carrying out the process. This allows very dynamic and changeable production processes, which are directly adaptable to the desired requirements.

In this case, the starting material can be provided, for example, as a large-area material, from which in each case a material part of a suitable size can be separated, for example punched out or cut out, before it can be used. As a result, only one starting material can be provided for a wide range of applications, which can further improve the costs for the above-described method.

Furthermore, the starting material, for example by film casting or injection molding, initially be provided, for example, as a particularly flexible film, which keeps the requirements for handling very low. This allows the starting material with conventional handling systems be handled, which can allow a particularly good integration of the starting material in existing process peripherals.

In this case, during or after application of the starting material to a component or when arranging the starting material between the components to be joined, as explained below, the starting material to potentially existing unevenness of the joining partners, such as substrate irregularities or component unevenness, optimally adapt, so that a particularly intimate contact is possible, which can also bring a particularly stable sintered compound with it.

In this case, the polymeric, polymerizable and / or monomeric organic compound and the background material or the at least one metal or the at least one metal compound are particularly matched to one another such that the polymeric, polymerizable and / or monomeric organic compound has a flow temperature which is greater than or equal to Room temperature and less than the sintering temperature of the background material, and wherein the polymeric, polymerizable and / or monomeric organic compound further has a desorption temperature which is greater than the flow temperature and less than or equal to the sintering temperature of the background material.

In the context of the present invention, a flow temperature can be understood to mean, in particular, a specific temperature or a temperature range from which the polymeric, polymerizable and / or monomeric organic compound is flowable and thus flowable, ie can be removed automatically from the joining zone by a flow process. In this case, a flow temperature can be understood in particular to be a melting temperature or a melting range or a glass transition temperature or glass transition range.

Such a selection of the background material or of the polymeric, polymerizable and / or monomeric organic compound permits significant advantages in the process control.

In particular, by selecting in particular the polymeric, polymerizable and / or monomeric organic compound it can be made possible that the starting material, in particular due to the polymeric, polymerizable and / or monomeric organic compound, has a good adhesive force and thus good adhesion to the components to be joined, such as a substrate and a component can adhere. In other words, the starting material, such as the polymeric, polymerizable and / or monomeric organic compound, or another excipient, such as a solvent, may have suitable tackiness that allows the starting material to adhere to the mating partners. This allows a particularly good applicability, since the starting material, once arranged, can safely remain there. For example, such an adhesion force or tackiness can be obtained at temperatures below the flow temperature, ie, purely by way of example, at temperatures in a range of less than or equal to 100 ° C.

In addition, the polymeric, polymerizable and / or monomeric organic compound can serve to prevent cold welding of the particles and also to allow shaping of the film material.

After providing a starting material designed as described above, this starting material is arranged according to method step b) between two components to be connected. This can be done fully automated, for example. In this case, the starting material can be arranged, for example, between a substrate and an electronic component to be mounted on the substrate.

In accordance with process step c), a further step is carried out to heat the starting material to a temperature T1 that is greater than or equal to the flow temperature of the polymeric, polymerizable and / or monomeric organic compound and less than the desorption temperature of the polymeric, polymerizable and / or monomeric organic compound for a time t1. By this method step, adhesion of the starting material to the components to be joined can be further improved. In this case, such a temperature T1 depending on the selected polymer, polymerizable and / or monomeric organic compound already at temperatures of less than or equal to 100 ° C, for example in a range of greater than or equal to 30 ° C to less than or equal to 80 ° C. In detail, for example, a stickiness or an adhesion force of the polymeric, polymerizable and / or monomeric organic compound can be further increased or such stickiness can be formed only by a flowability. Thus, it can be made possible in this step that the starting material firmly adheres between the components to be joined and thus already forms an arrangement which already has a good stability for the further sintering process.

By this method step can thus be made possible that the starting material a desired position is arranged, and further remains there. As a result, specially defined products can be obtained. In this case, the starting material, in particular stable forces, can be held in its position by raising the temperature above the flow temperature of the polymerizable polymerizable and / or monomeric organic compound. Thus, an additional fixation medium is not necessary, which can make the method described above particularly simple and inexpensive.

Furthermore, the polymeric, polymerizable and / or monomeric organic compound, in particular in a flowable state, can serve as a dispersing medium in order to form a homogeneous starting material.

In addition, it can be made possible by flowability of the polymeric, polymerizable and / or monomeric organic compound that the starting material conforms to the components to be joined and otherwise by a particular reversible softening of the polymeric, polymerizable and / or monomeric organic compound by the temperature increase the flow temperature creates a good match between the layer of the starting material and the joining partners. Thus, an intimate contact of the metallic compound or of the background material with the components to be joined can equally be allowed. This can contribute to a particularly stable arrangement after sintering, as explained below.

However, since only a very small amount of polymeric, polymerizable and / or monomeric organic compound is necessary for tackiness or conformability and the fixation of the starting material between the joining partners, the further advantage can be achieved that the majority of the polymeric, polymerizable and / or monomeric organic compound is removed by a fluidity of the joining zone. It can thereby be achieved that, in the case of a subsequent removal or desorption of the polymeric, polymerizable and / or monomeric organic compound from the joining region, there is no or not substantial development of reaction gases which optionally expand in the joint and thus the formation of a cohesive connection could counteract. Furthermore, for example and depending on the desorption chosen, no oxygen is required, as a result of which the sintered compound can also take place in the absence of oxygen. This can avoid a change or damage to all parties joining a temperature treatment. In addition, the need for supply of gases or the need for the discharge of gases can be prevented. Thus, it is not disadvantageous in the above-described method that, especially in large-area compounds, the gas transport is limited by the density of the joining material and thus, for example, in a production of a tight connection, the material is pressed by mechanical pressure and thus just inhibits the gas transport. Thus, in summary, by raising the temperature above the flow temperature of the polymeric, polymerizable and / or monomeric organic compound, the disadvantages of removing such a matrix according to the prior art can be prevented.

The time duration t1, for which the temperature T1 is maintained, can be selected depending on the actual starting material used. In particular, the period of time should be long enough for sufficient flowability of the polymeric, polymerizable and / or monomeric organic compound to be realized, and for the aforementioned advantages to be achieved in a particularly advantageous manner.

In a further method step d), in a method described above, the starting material is heated to a temperature T2 that is greater than or equal to the sintering temperature of the sinterable particles, optionally under the effect of a sintering pressure, for a period t2 to form a sintered compound. In this process step thus the actual sintered connection is generated.

The chemically stabilized particles, for example, are burnt out until the bonding temperature or sintering temperature is reached, so that the particles or released metal atoms come into direct contact with one another and with the material of the joining partners. By solid-state processes, a high-temperature-stable compound then forms even at low temperatures.

For this purpose, the starting material is heated alone or together with at least one joining region of the components to be connected to a temperature T2, for example by a heating source or electromagnetic radiation. In this case, the temperature T2 is greater than or equal to the sintering temperature of the sinterable particles, ie the particles, comprising at least one metal or at least one metal compound. In this case, the temperature T2 is maintained for a predetermined period of time t2, which is sufficient for a stable sintered connection to form.

The fact that the polymeric, polymerizable and / or monomeric organic compound furthermore has a desorption temperature, that is to say a specific desorption temperature or a broad desorption temperature, that is to say a desorption range which is greater than the flow temperature and less than or equal to the sintering temperature, can be the stability of the trained sintered compound can be further increased. In detail, the polymeric, polymerizable and / or monomeric organic compound is desorbed both from the sinterable particles and from the components to be joined, that is removed in the context of the present invention. It can thus be ensured that, after the formation of the sintered connection, this essentially comprises only the sintered particles or sintered products thereof. Therefore, the polymeric, polymerizable and / or monomeric organic compound does not disturb the stability of the sintered compound, whereby particularly stable products can be obtained.

In summary, the method described above makes it possible in particular for a particularly simple and defined production of a sintered connection between two components to be joined, wherein the formed sintered connection can furthermore be particularly stable.

In the context of one embodiment, the desorption temperature may be the boiling temperature, decomposition temperature or a reaction temperature of the polymeric, polymerizable and / or monomeric organic compound with the sinterable and / or with sintered particles. In particular, in this embodiment can be advantageously ensured that in the process step d) the polymeric, polymerizable and / or monomeric organic compound can be removed completely or without residue and the polymer, polymerizable and / or monomeric organic compound thus does not adversely affect the stability of the sintered compound , The fact that at least a certain proportion or advantageously a large part of the polymeric, polymerizable and / or monomeric organic compound is no longer disposed in the immediate joining zone during process step d), can also by evaporation, decomposition or combustion or Abreagieren, such as Oxidizing by a constituent of the sintered material, which in particular arranged outside the joining zone polymer, polymerizable and / or monomeric organic compound is not in the risk that a significant gas generation adversely affects the sintering process. The proportion of the polymer, polymerizable and / or monomeric organic compound still in the joining zone can be so low in particular that no significant gas transport takes place, which adversely affects the forming sintered compound or the stability of the formed sintered connection. Thus, even a removal by the abovementioned processes can be possible without any problems here, or it may also be possible for the polymeric, polymerizable and / or monomeric organic compound in the joining zone to remain in place without negatively influencing the sintering process.

Within the scope of a further embodiment, the sinterable particles silver, gold, platinum, palladium and / or copper, an organic metal compound, in particular silver carbonate, silver lactate or silver stearate, a metal oxide, in particular silver oxide, or a mixture containing one or more of the aforementioned substances. Such particles may be particularly advantageously suitable for forming a highly stable and electrically conductive sintered compound. In this case, both the pure metals and corresponding metal compounds can be provided. The metals can allow directly by a heat input or an entry of pressure in particular a cohesive connection between the joining partners, thereby enabling a stable sintered connection. With respect to the above-mentioned metal compounds, they may be formed by subjecting the starting material to a temperature treatment such as in a range lower than 300 ° C, decomposing to form the elemental metal and sintering compound. When using the described starting material, contacting can already take place with low contact pressures of the contacting partners, which can thus allow mild reaction conditions and thus a simple and cost-effective method.

Within the scope of a further embodiment, the polymeric, polymerizable and / or monomeric organic compound may comprise a polyolefin, in particular comprising polyethylene and / or polypropylene, a polyethylene copolymer, a polyketone or a mixture comprising one or more of the abovementioned substances. In particular, such polymeric, polymerizable and / or monomeric organic compounds may have the advantage that they can be easily integrated into a sintering process with regard to their flow temperature or their desorption behavior, in particular in combination with the aforementioned background materials, ie in particular metals or metal compounds. Thus, the aforementioned polymeric, polymerizable and / or monomeric organic compounds particularly advantageous to be suitable to receive the background material and thereby further substantially residue-free by a desorption of a component to be joined to be removed. In addition, the above-mentioned polymeric, polymerizable and / or monomeric organic compounds are stable under ambient conditions, ie also in an oxidative atmosphere and / or in a humid atmosphere, so that a particularly advantageous storage life can also be achieved over a long period of time for the starting material.

Within the scope of a further embodiment, the polymeric, polymerizable and / or monomeric organic compound can form a matrix in which the sinterable particles are embedded, or the polymeric, polymerizable and / or monomeric organic compound can be present as a coating on the sinterable particles. These are particularly advantageous embodiments in order to surround the sinterable particles of the polymeric, polymerizable and / or monomeric organic compound.

With regard to a matrix in which the sinterable particles are embedded, a shaped body can thus be produced which can be adaptable in all dimensions to the desired field of application. In detail, such a body in its length, width and height can be adapted to the components to be joined. Thereby, the method can be further facilitated and also made more cost-effective. For example, such a mutually adhering moldable mass can be produced, which can be handled particularly well. In this case, such a starting material can be produced approximately by melting the polymer, polymerizable and / or monomeric organic compound with subsequent mixing with the background material and a final cooling.

With respect to a coating, the proportion of the polymeric, polymerizable and / or monomeric organic compound can be kept particularly low, so that the mass emerging from the joining region when the temperature rises above the flow temperature of the polymeric, polymerizable and / or monomeric organic compound can be kept particularly low , Thus, the process can be carried out particularly time-saving. In this case, the coating of the particles can be applied already in the production of the particles, in particular in order to prevent a reaction of the sinterable particles with one another, such as a cold welding. For example, the metal particles, which are produced, for example as silver particles, by a vapor deposition or precipitation in a solvent, can be coated by the solution having a corresponding coating material, for example as a surface-active material. After removal of the solvent, for example, the starting materials which can be handled approximately as powders comprising the sinterable particles with the in particular chemically or physically bound coating can be obtained.

In these embodiments, the starting material can now be applied as a powder or as a compact from the powder or as a paste with a solvent via basically known methods, such as placing the green body, or brought into contact with the components to be joined. Also in these embodiments, the viscosity of the polymer, polymerizable and / or monomeric organic compound can be adjusted via a temperature control, so that the viscosity can be controlled by a temperature setting and thereby increase the temperature can cause the compound in particular by capillary forces removed from the joint and can be completely removed or desorbed in a further process step.

In a further embodiment, the starting material can be applied to at least one component to be joined by printing, doctoring or dispensing. These are particularly simple and sophisticated processes for applying the starting material to at least one of the components to be joined. In these embodiments, a particularly precise and highly accurate arrangement of the starting material is possible, which can allow highly stable sintered connections even in small-sized components. In this case, the starting material can be applied to only one of the components to be connected, or to use both on the output components.

In a further embodiment, the starting material may comprise a transfer layer which is arranged between at least two protective layers, in particular comprising a polymeric, polymerizable and / or monomeric organic compound. For example, the transfer layer may comprise the background material or the sinterable particles and optionally the polymeric, polymerizable and / or monomeric organic compound. In this case, the polymeric, polymerizable and / or monomeric organic compound of the transfer layer may be the same compound as the compound of the protective layers. Alternatively, it is possible to dispense with the polymeric, polymerizable and / or monomeric organic compound in the transfer layer, which can enclose the sinterable particles directly as a coating or as a matrix, for example, so that the sinterable particles can only be covered by the protective layers comprising a polymeric, polymerizable and / or or monomeric organic compound are surrounded. In this embodiment, the starting material be very easy to handle and still be arranged very precisely at the desired location. The transfer layer is particularly well protected against external influences and thus particularly storable.

In this case, arranging the starting material on one of the components to be joined, by way of example and not limitation, can be realized in such a way that the protective layers are removed before or during method step b). In this case, by way of example, first a protective layer can be removed and the exposed side of the transfer layer can be arranged on the component, and subsequently the further protective layer can be removed. Thus, the starting material may in particular have a transfer layer, which is surrounded on two opposite sides of the protective layer. In this case, the protective layers can furthermore be designed such that essentially the entire transfer layer is surrounded by protective layers. This can be achieved by providing more than two protective layers as well as by a corresponding shape of the at least two protective layers.

In this case, in particular in this embodiment, application of the background material by printing, dispensing or knife coating with a subsequent temperature treatment for drying the applied layer can be dispensed with. Therefore, the method described above can save on process steps, in particular in this embodiment, which can save manufacturing costs of the components to be produced as well as time for producing such components.

In a further embodiment, the protective layers may comprise polyethylene terephthalate. In particular, polyethylene terephthalate can serve as a stable protective layer to safely protect the transfer layer from external influences such as mechanical influences. In addition, it is inert with respect to the materials occurring in the transfer layer, so that no negative influence on the transfer layer is to be expected over a longer period of storage. Furthermore, polyethylene terephthalate can be obtained inexpensively, so that the method can also be realized particularly inexpensively in this embodiment.

In a further embodiment, the starting material may be provided in the form of a paste, a powder, a granulate or a film. Such forms of the starting material can be handled easily, inexpensively and with known methods, so that the method can be particularly simple and inexpensive, especially in these embodiments. In addition, storage without hesitation is possible, so that the advantages in terms of production in advance and an application or provision immediately before the process can be easily possible.

In a further embodiment, the polymeric, polymerizable and / or monomeric organic compound can be removed or removed during or after process step c). In this embodiment, the effect basically occurring by a flowability of the polymer, polymerizable and / or monomeric organic compound, according to which the compound from the joint zone already occurs by flowing away, can be further enhanced or supported.

With regard to a derivation of the polymeric, polymerizable and / or monomeric organic compound, it is possible, for example, to provide one or a plurality of collecting containers, such as cavities, into which the flowable compound can be derived, ie, guided. For this purpose, channels may be provided, for example, which are arranged in such a way that the compound flows in a flowable state, or the collecting containers may themselves be arranged directly in such a way that the flowable connection flows in there. In this case, the collecting container can be arranged approximately immediately adjacent to the components to be joined and the channels extend approximately into the joining region.

With regard to removal of the polymeric, polymerizable and / or monomeric organic compound, the flowable compound can be taken up and removed, for example, by means of a suitable device.

For this example, spongy devices or capillary bundles can be used, which absorb the compound by means of capillary forces or can suck. This can cause a particularly gentle removal of the compound and not adversely affect the sintering process.

Within the scope of a further embodiment, the polymeric, polymerizable and / or monomeric organic compound may comprise at least one additive which reacts with the sinterable particles, in particular with the organic metal compound, while reducing the sintering temperature. In particular, in this embodiment, a particularly gentle method can be made possible, since even low temperatures can be sufficient for a sintering process. As a result, such components can be connected to each other, which should not be exposed to high temperatures. In addition, polymeric, polymerizable and / or monomeric organic Compounds which have a relatively low desorption temperature can be used, which may increase the selection of such compounds also with respect to conventional polymers, for example. As exemplary and non-limiting examples of such additives may be mentioned oxidizable organic compounds, such as fatty acids, for example stearic acid or lauric acid, in particular in combination with the aforementioned background materials, such as silver.

In a further embodiment, a sintered connection can be produced which has an electrical conductivity of greater than or equal to 30 MS / m to, in particular, less than or equal to 45 MS / m, in particular greater than or equal to 36 MS / m to in particular less than or equal to 44 MS / m, and / or a sintered compound can be produced which has a thermal conductivity of greater than or equal to 200 W / mK to less than or equal to 300 W / mK, in particular greater than or equal to 220 W / mK to less than or equal to 275 W / mK. In particular, such a sintered connection can be used for a large number of electronic components which may be used in power electronics. Such conductivities can be achieved, for example, by the use of the above-described background materials.

Within the scope of a further embodiment, an electronic component can be used as one of the components to be connected, and a substrate, for example comprising a copper compound, can be used as another of the components to be connected. In this embodiment, in particular electronic components can be applied to the corresponding substrates. Especially in such applications, a very stable compound which is additionally electrically conductive is useful. Therefore, it is particularly advantageous in this embodiment that the sintered connection can be positioned with high accuracy and furthermore that no gas transport processes have a substantially negative influence on the formation of a stable connection layer. For example, this embodiment, in particular an electronic component of the power electronics can be produced.

With regard to further technical features and advantages of the method according to the invention, reference is hereby explicitly made to the explanations in connection with the use according to the invention, the figures and the description of the figures.

The subject matter of the present invention is furthermore a use of a method configured as described above for producing an electronic component, in particular an electronic circuit. In this use, therefore, an electronic component or an electronic circuit can be produced by, in particular, fixing an electronic component to a substrate by a sintering process. In this case, for example, power semiconductors or integrated circuits can be attached to the substrate as electronic components by the sintered connection. In particular, the method described above can be used for components to be joined, which should only be exposed to a low temperature load, since the temperatures necessary for flowability or for desorbing the polymeric, polymerizable and / or monomeric organic compound and for sintering the background material in a method described above due to the selection of the starting material can also be kept low. For example, in this embodiment, silicon chips or silicon carbide components, which can withstand temperatures of, for example, 250 ° C. or 350 ° C., can be joined without problems, for example the so-called "die attach".

Basically, this embodiment thus comprises a use of the above-described method in the field of electronic construction technology or connection technology, in particular as a low-temperature sintering technique. For example, diffusion soldering or active soldering can be replaced by the method described above.

With regard to further technical features and advantages of the use according to the invention, reference is hereby explicitly made to the explanations in connection with the method according to the invention, the figures and the description of the figures.

Examples and drawings

Further advantages and advantageous embodiments of the subject invention are illustrated by the examples and drawings and explained in the following description. It should be noted that the examples and drawings are only descriptive and are not intended to limit the invention in any way. Show it

1a C is a schematic representation of a production of an embodiment of a starting material for a method according to the invention;

2a C is a schematic representation of a method according to the invention using a starting material according to 1 ; and

3a C is a schematic representation of a method according to the invention using a further embodiment of a starting material

In 1c is a starting material 10 for a method according to the invention for joining at least two components using a sintering process. The starting material 10 a sintered connection in the embodiment according to 1c includes sinterable particles 12 comprising at least one metal or at least one metal compound. Furthermore, the starting material comprises 10 at least one polymeric, polymerizable and / or monomeric organic compound 14 according to 1 as a coating on the sinterable particles 12 is arranged. Here are the sinterable particles 12 or the polymeric, polymerizable and / or monomeric organic compound 14 such that the polymeric, polymerizable and / or monomeric organic compound 14 has a flow temperature which is greater than or equal to room temperature, that is according to the invention greater than or equal to 22 ° C, and less than the sintering temperature of the sinterable particles, and wherein the polymeric, polymerizable and / or monomeric organic compound 14 Further, it has a desorption temperature greater than the flow temperature and less than or equal to the sintering temperature.

It is in 1 an exemplary manufacturing process of the starting material 10 shown. In 1a is a sinterable particle 12 shown in a solvent 16 was produced. The sinterable particle 12 may be, for example, a silver particle. In the 1b is further shown that on the sinterable particles 12 a coating of a polymeric, polymerizable and / or monomeric organic compound 14 is arranged. This can be produced by the polymeric, polymerizable and / or monomeric organic compound 14 to the solvent 16 given, for example, dissolved or dispersed, is. By way of example, as a polymeric, polymerizable and / or monomeric organic compound 14 a rosin resin, which can serve as a flux find use. With regard to the process according to the invention, this has the advantage that it is soft and sticky at slightly elevated temperatures of well below 100.degree. C., but volatilizes almost without residue with decomposition in the further process control and can be produced as a preform at 25.degree. In the 1c is the finished starting material 10 as described above, by evaporation of the solvent.

Such a starting material 10 can be directly between two components to connect 18 . 20 be arranged as in the 2a is shown. In this case, the starting material 10 on at least one component to be connected 20 be applied by printing, knife coating or dispensing. For example, the component 20 a substrate, whereas the component 18 an electronic device, such as a power semiconductor device may be.

In the 2 B a first temperature treatment step is shown. In detail is in the 2 a state shown after a process step comprising heating the starting material 10 to a temperature T1 greater than or equal to the flow temperature of the polymeric, polymerizable and / or monomeric organic compound 14 and smaller than the desorption temperature of the polymeric, polymerizable and / or monomeric organic compound 14 is for a time t1. As a result, part of the polymeric, polymerizable and / or monomeric organic compound 14 is removed from the joining zone and on the component 20 arranges or the surface of the component 20 wetted. In this case, the polymeric, polymerizable and / or monomeric organic compound 14 be derived or removed during or after this process step of the first heat treatment.

In the 2c is also a formed sintered connection 22 of the two components 18 . 20 shown. Such a sintered compound 22 is formed by sintered sinterable particles 12 by a further process step comprising heating the starting material 10 to a temperature T2 that is greater than or equal to the sintering temperature of the sinterable particles 10 is, optionally under the action of a sintering pressure, for a temperature t2 to form a sintered compound 22 , The sintered connection 22 can, for example, when using silver as sinterable particles 12 , have an electrical conductivity of greater than or equal to 30 MS / m to in particular less than or equal to 45 MS / m, in particular greater than or equal to 36 MS / m to in particular less than or equal to 44 MS / m, and / or may have a thermal conductivity from greater than or equal to 200 W / mK to less than or equal to 300 W / mK, in particular from greater than or equal to 220 W / mK to less than or equal to 275 W / mK. Furthermore, sintering may take place by way of example at a sintering pressure of less than or equal to 10 MPa, for example less than or equal to 1 MPa and / or at a sintering temperature in a range of less than or equal to 300 ° C, for example less than or equal to 250 ° C.

In the 3a to 3c is a further embodiment of a starting material 10 and a method performed thereby. In the embodiment according to 3a forms the polymeric, polymerizable and / or monomeric organic compound 14 a matrix in which the sinterable particles 12 are embedded. In this case, the polymeric, polymerizable and / or monomeric organic compound 14 together with the sinterable particles 12 in a transfer layer 24 , arranged as an adhesive film. The transfer layer 24 is between at least two protective layers 26 . 28 in particular comprising a polymeric, polymerizable and / or monomeric organic compound 30 arranged.

To a sintered connection 22 At first, a protective layer can be formed 28 removed and the starting material 10 on the first component 20 be transmitted. After removing the second protective layer 26 Reference meadow of all existing protective layers is the second component 18 accordingly on the starting material 10 or on the transfer layer 14 positioned. Here and optionally also in further process steps of the starting material 10 spoken although at least partially only a part of the starting material is present, which in the context of the invention, however, starting material 10 can be included. This condition is in 3b shown.

This can be followed by a first temperature treatment, in which the polymeric, polymerizable and / or monomeric organic compound 14 melts and can become sticky, for example. In the sintering process, the polymeric, polymerizable and / or monomeric organic compound 14 are removed and further by the increased temperature, the sintered sinterable particles, a sintered compound 22 train like this in the 3c is shown.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007046901 A1 [0005]
• EP 2278593 A1 [0006]
• US 20080211095 A1 [0007]
• US 6832915 B2 [0008]
• DE 10200727999 A1 [0009]
• DE 102004019567 B3 [0010]
• JP 63258084 A [0011]
• US 6951666 [0012]

Claims (15)

Method for connecting at least two components ( 18 . 20 ) using a sintering process, comprising the method steps: a) providing a starting material ( 10 ) a sintered compound ( 22 ) comprising sinterable particles ( 12 ), comprising at least one metal or at least one metal compound, and at least one polymeric, polymerizable and / or monomeric organic compound ( 14 ), wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) has a flow temperature which is greater than or equal to room temperature and less than the sintering temperature, and wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) further has a desorption temperature which is greater than the flow temperature and less than or equal to the sintering temperature; b) arranging the starting material ( 10 ) between two components to be connected ( 18 . 20 ); c) heating the starting material ( 10 ) to a temperature T1 which is greater than or equal to the flow temperature of the polymeric, polymerizable and / or monomeric organic compound ( 14 ) and less than the desorption temperature of the polymeric, polymerizable and / or monomeric organic compound ( 14 ) is for a time t1; and d) heating the starting material ( 10 ) to a temperature T2 that is greater than or equal to the sintering temperature of the sinterable particles ( 12 ) is, optionally under the action of a sintering pressure, for a period t2 to form a sintered compound ( 22 ). Process according to claim 1, wherein the desorption temperature is the boiling temperature, decomposition temperature or a reaction temperature of the polymeric, polymerizable and / or monomeric organic compound ( 14 ) with the sinterable and / or with sintered particles ( 12 ). Process according to claim 1 or 2, wherein the sinterable particles ( 12 ) Silver, gold, platinum, palladium and / or copper, an organic metal compound, in particular silver carbonate, silver lactate or silver stearate, a metal oxide, in particular silver oxide, or a mixture comprising one or more of the aforementioned substances. Method according to one of claims 1 to 3, wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) a polyolefin, in particular comprising polyethylene and / or polypropylene, a polyethylene copolymer, a polyketone or a mixture comprising one or more of the aforementioned substances. Method according to one of claims 1 to 4, wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) forms a matrix in which the sinterable particles ( 12 embedded image, or wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) as a coating on the sinterable particles ( 12 ) is present. Method according to one of claims 1 to 5, wherein the starting material ( 10 ) is applied to at least one component to be joined by printing, knife coating or dispensing. Method according to one of claims 1 to 5, wherein the starting material ( 10 ) a transfer layer ( 24 ) between at least two protective layers ( 26 . 28 ) is arranged in particular comprising a polymeric, polymerizable and / or monomeric organic compound. Method according to claim 7, wherein the protective layers ( 26 . 28 ) are removed before or at process step b). Method according to claim 7 or 8, wherein the protective layers ( 26 . 28 ) Comprise polyethylene terephthalate. Method according to one of claims 1 to 9, wherein the starting material ( 10 ) is provided in the form of a paste, a powder, a granule or a film. Method according to one of claims 1 to 10, wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) is discharged or removed during or after process step c). Method according to one of claims 1 to 11, wherein the polymeric, polymerizable and / or monomeric organic compound ( 14 ) contains at least one additive which is compatible with the sinterable particles ( 12 ), in particular with the organic metal compound, with reduction of the sintering temperature. Method according to one of claims 1 to 12, wherein a sintered compound ( 22 ), which has an electrical conductivity of greater than or equal to 30 MS / m to in particular less than or equal to 45 MS / m, in particular greater than or equal to 36 MS / m to in particular less than or equal to 44 MS / m, and / or wherein a sintered compound ( 22 ), which has a thermal conductivity of greater than or equal to 200 W / mK to less than or equal to 300 W / mK, in particular from greater than or equal to 220 W / mK to less than or equal to 275 W / mK. Method according to one of claims 1 to 13, wherein as one of the components to be joined ( 18 ) an electronic component and as a further of the components to be connected ( 20 ), a substrate, in particular comprising a copper compound, is used. Use of a method according to one of claims 1 to 14 for producing an electronic component, in particular an electronic circuit.

Images