Highly porous scaffold-structure copper-contact production method and highly porous scaffold-structure copper-contact arrangement

Abstract

The invention relates to a highly porous scaffold-structure copper-contact production method for producing a copper contact on a highly porous scaffold structure, and to a highly porous scaffold-structure copper-contact arrangement, wherein the highly porous scaffold structure and the copper contact form a mixing zone of at least 1 μm. The production method comprises the following steps: producing a highly porous structure from zinc oxide, said structure being encased and / or infiltrated by an electrically conductive material; applying copper to the structure; heating to a temperature ≥ 700 °C in an atmosphere of hydrogen and inert gas, wherein the zinc oxide is reduced by the hydrogen, a highly porous scaffold structure is formed from the electrically conductive material, remaining zinc transitions to the gas phase, the copper melts to form a thin film on the highly porous scaffold structure, zinc vapour is absorbed by the copper melt; cooling and allowing a solid zinc-containing copper contact to form on the formed highly porous scaffold structure.

Description

[0001] HIGHLY POROUS SCAFCOPPER CONTACT MANUFACTURING PROCESS

[0002] AND HIGHLY POROUS FRAMEWORK STRUCTURE-COPPER CONTACT ARRANGEMENT

[0003] The invention relates to a highly porous framework structure-copper contact manufacturing method for producing a copper contact on a highly porous framework structure and a highly porous framework structure-copper contact arrangement, wherein the highly porous framework structure and the copper contact form a mixing zone of at least 1 pm,

[0004] According to the state of the art, the electrical contacting of highly porous conductive framework materials is achieved by applying conductive pastes such as silver conductive paste.

[0005] Another method involves clamping highly porous conductive scaffold materials between two metal clamps.

[0006] Other alternative methods for electrical contacting include the deposition of metal ions from the gas or fluid phase or the directed “bombardment” of the surface to be contacted with metal atoms or ions.

[0007] The publication DE 10 2020 110 746 A1 deals with the electrical heating of carbon-based aeromaterials, whereby the electrical contact is made with silver conductive paste.

[0008] In “Electrically powered repeatable air explosions using microtubular graphene assemblies”, Materials Today, Volume 48, 2021 , Pages 7-17, ISSN 1369-7021, https: / / doi.Org / 10.1016 / j.mattod.2021.03.010, F. Schütt, F. Rasch et al. contact aerographs electrically using silver paste.

[0009] From the publication DE 20 2012 011 892 U1 and from the publication US 2014 / 0 162 001 A1, the production of aerographite on a zinc oxide template by carbon deposition from the gas phase with simultaneous dissolution of the template is known.

[0010] Furthermore, Gröttrup, Jorit, et al., "Three-dimensional flexible ceramics based on interconnected network of highly porous pure and metal alloyed ZnO tetrapods," in: Ceramics International 42.7 (2016): 8664-8676, demonstrate that flexible and porous three-dimensional (3D) ceramics made of inorganic metal oxide nano- and microstructures are promising material candidates for future nanotechnologies. Here, 3D networks based on pure and metal (M) alloyed ZnO nano- and micro-tetrapods (ZnO-T) were synthesized using a versatile flame transport synthesis route. These ZnO-T networks were alloyed with various metals (Al, Cu, Sn, etc.) and characterized in detail for various properties.The porosity of these interconnected 3D networks was tuned by controlling the initial tetrapod concentrations and the M alloying level, allowing the synthesis of metal-doped highly porous networks (up to 98%).

[0011] The main problems with the current state of the art are that electrical contacting using conductive pastes is expensive, and the application of the pastes is sometimes unsatisfactory. For example, if soldering is performed selectively, reliable contact is achieved only at the soldering points. This method is not suitable for uniformly contacting larger surfaces with minimal effort.

[0012] Electrical contacting by clamping the highly porous conductive framework materials between two metal clamps has the particular disadvantage that there is an extremely low contact area between the metal and the highly porous framework structure, which leads to damage to the framework structure, especially at high electrical currents.

[0013] If deposition processes are used for electrical contact, the problem arises that not only the desired contact surface but also more or less large areas of the interior of the framework structure are coated.

[0014] By "bombarding" the surface to be contacted with metal atoms or ions, a coating limited to the immediate vicinity of the contact surface is obtained; however, an encapsulation of individual tubes of the framework structure is not achieved in this way.

[0015] The present invention is based on the object of providing a method with which a stable electrical contact can be created between a conductive porous framework structure and a metal, which is free from the disadvantages mentioned above.

[0016] This object is achieved with a highly porous framework structure copper contact manufacturing method according to the main claim and a highly porous framework structure copper contact arrangement according to the independent claim.

[0017] The highly porous framework copper contact manufacturing method for producing a copper contact on a highly porous framework, wherein the highly porous framework and the copper contact form a mixing zone of at least 1 pm, comprises the following steps:

[0018] - Producing a highly porous structure made of zinc oxide coated and / or infiltrated with an electrically conductive material;

[0019] - Applying copper to the structure;

[0020] - heating to a temperature > 700 °C in an atmosphere of hydrogen and inert gas, whereby - the zinc oxide is reduced by the hydrogen;

[0021] - a highly porous framework structure is formed from the electrically conductive material;

[0022] - remaining zinc passes into the gas phase;

[0023] - the copper melts into a thin film on the highly porous framework structure;

[0024] - zinc vapor is absorbed by the copper melt;

[0025] - Cooling and allowing a solid zinc-containing copper contact to form on the formed highly porous framework structure.

[0026] The copper can be introduced in particular in the form of powder and / or foil.

[0027] In addition, in a preferred embodiment, the electrically conductive material can be a carbon material and / or graphene and / or graphite.

[0028] Preferably, the highly porous framework structure can be in the form of an aeromaterial.

[0029] The formed thin film of copper and zinc may have a composition resulting in brass.

[0030] The temperature of > 700 °C may preferably be applied for a time of > 2 hours and / or > 3.5 hours and / or > 5 hours.

[0031] Heating to temperatures between 700 °C and 900 °C can also be carried out.

[0032] The highly porous structure of zinc oxide can be formed in particular from tetrapodal zinc oxide.

[0033] The highly porous framework structure-copper contact arrangement with a copper contact on a highly porous framework structure produced by the highly porous framework structure-copper contact production method is characterized in that a copper contact is arranged on a highly porous framework structure, wherein the highly porous framework structure and the copper contact form a mixing zone of at least 1 pm.

[0034] The copper contact on the highly porous framework structure can in particular be designed as a coherent and flatly connected contact.

[0035] By applying a thin layer of preferably copper micropowder or nanopowder, or optionally also copper foil, to a highly porous structure made of zinc oxide, coated with the later conductive, highly porous framework structure, in particular in the form of an aeromaterial, heating the layer to at least 700°C in an atmosphere of hydrogen and inert gas creates a layer of continuously sintered, preferably brass particles that envelop a portion of the preferably aeromaterial, in particular made of carbon, or its components (hollow microtubes), thus forming a coherent and flat "monolithic" contact. The preferably aeromaterial and the metal have a mixing zone of at least 1 m. Even during thermal cycling of the highly porous framework structure-copper contact arrangement, no detachment of the metal from the highly porous framework structure occurs.The thin film of metal on the framework structure adheres firmly, particularly due to the cross-contacting (mixing zone of at least 1 pm).

[0036] The manufacturing method according to the invention offers several advantages. It enables cost-effective electrical contacting. At the same time, controlled contacting of individual areas is possible. The contacting and dissolution of the zinc oxide take place in a single process step during the production of the highly porous framework structure, in this case particularly in the form of an aeromaterial. The brass contact, in particular, or also a contact made of a copper-zinc alloy, serves to reinforce the highly porous framework structure and allows for improved handling. Furthermore, simple electrical integration, such as through conventional soldering, is enabled.

[0037] The electrical contacting of highly porous framework structures, especially aeromaterials, is crucial for a wide range of applications.

[0038] The invention is described below with reference to the accompanying figures in the description of the figures, which are intended to illustrate the invention and are not to be considered limiting. They show:

[0039] Figure 1 shows an exemplary representation of a highly porous framework copper contact arrangement according to the invention in the form of SEM images with a) an SEM close-up of a graphene hollow tube and an SEM image of a graphene network and

[0040] Figure 2 is a graphical representation of an exemplary temperature profile of the highly porous framework copper contact manufacturing process according to the invention.

[0041] Figure 1 shows an exemplary representation of a highly porous framework-copper contact arrangement according to the invention in the form of SEM images. Fig. 1a) shows a close-up SEM image of a hollow graphene tube with adhering individual copper particles. Fig. 1b) shows an SEM image of an array of hollow graphene tetrapods partially covered and enclosed with copper.

[0042] Fig. 2 shows a graphical representation of an exemplary temperature profile when carrying out the highly porous framework copper contact manufacturing process according to the invention.

[0043] Further example:

[0044] The following is a description of the highly porous framework copper contact manufacturing process according to the invention based on a concrete embodiment with reference to the previously explained figures, which are intended to explain the invention and are not to be considered limiting:

[0045] Tetrapodal zinc oxide becomes a sacrificial template with a density of 0.3 g / cm 3(porosity approx. 94%) and sintered for 5 hours at 1150 °C. The produced template is then infiltrated six times with exfoliated graphene platelets dispersed in water at a concentration of 1.4 g / ml. The infiltrated template is dried and, after drying, a thin layer (< 1 mm) of copper powder is applied using a spatula. The prepared sample is fed into a furnace with a protective gas retort. According to the temperature profile shown in Fig. 2, the sample is heated to 900 °C in a forming gas atmosphere (90% nitrogen, 10% hydrogen) with a continuous gas flow of 4 l / min. The underlying sacrificial template made of tetrapodal zinc oxide is reduced by the hydrogen, i.e. removed by etching. The remaining zinc enters the gas phase and the formerly powdery copper layer melts into a thin film on the sample surface, which partially wets it.In this process, zinc vapor is absorbed by the copper melt, transforming the thin film into a brass film. The SEM images show the formed copper layer on the graphene structure (brighter contrast) (Fig. 1b).

Claims

CLAIMS 1. A highly porous framework copper contact manufacturing method for producing a copper contact on a highly porous framework, wherein the highly porous framework and the copper contact form a mixing zone of at least 1 pm, comprising the following steps: - producing a highly porous structure made of zinc oxide coated and / or infiltrated with an electrically conductive material; - Applying copper to the structure; - Heating to a temperature > 700 °C in an atmosphere of hydrogen and inert gas, where - the zinc oxide is reduced by the hydrogen; - a highly porous framework structure is formed from the electrically conductive material; - remaining zinc passes into the gas phase; - the copper melts into a thin film on the highly porous framework structure; - zinc vapor is absorbed by the copper melt; - Cooling and allowing a solid zinc-containing copper contact to form on the formed highly porous framework structure.

2. Method according to claim 1, characterized in that the copper is introduced in the form of powder and / or foil.

3. Method according to claim 1 or claim 2, characterized in that the electrically conductive material is a carbon material and / or graphene and / or graphite.

4. Method according to one of the preceding claims, characterized in that the highly porous framework structure is in the form of an aeromaterial.

5. A method according to any one of the preceding claims, characterized in that the formed thin film of copper and zinc has a composition resulting in brass.

6. Method according to one of the preceding claims, characterized in that the temperature of > 700 °C is applied for a time of > 2 hours and / or > 3.5 hours and / or > 5 hours.

7. A method according to any one of the preceding claims, characterized in that the heating can be carried out at temperatures between 700 °C and 900 °C.

8. Method according to one of the preceding claims, characterized in that the highly porous structure of zinc oxide is formed from tetrapodal zinc oxide.

9. Highly porous framework structure copper contact arrangement with a copper contact on a highly porous framework structure produced by the highly porous framework structure copper contact production method according to claim 1, characterized in that a copper contact is arranged on a highly porous framework structure, wherein the highly porous framework structure and the copper contact form a mixing zone of at least 1 pm.

10. Highly porous framework structure-copper contact arrangement according to the preceding claim, characterized in that the copper contact on the highly porous framework structure is formed as a coherent and planarly connected contact.

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