Electronic unit with an integrated circuit and method for its manufacture

Abstract

Electronic unit (1), comprising: • a first component (2) with several first electrical contacts (3) comprising an integrated circuit (6), and • a second component (4) with several second electrical contacts (5), wherein the first electrical contacts (3) and the second electrical contacts (5) are each electrically connected to each other via an electrically conductive structure (8) which has a plurality of electrically conductive particles (9), characterized by the fact that the particles (9) are functionalized with a first functional group (R1), and that the first contacts (3) and / or the second contacts (5) are functionalized with a second functional group (R2) different from the first functional group (R1).

Description

[0001] The invention relates to an electronic unit with an integrated circuit and a connection technology for electrically connecting two components of an electronic unit.

[0002] In electronics manufacturing, the individual fragments (chips) of a wafer are usually attached to a carrier structure and electrically connected to it. This is also known as chip bonding or die bonding. The carrier structure can be, for example, the housing of a chip or, in the case of chip-on-board technology, a substrate such as a printed circuit board, a ceramic substrate, or a thick-film circuit, which can also support additional components. A chip can also be arranged on another chip (chip-on-chip technology), whereby a stack arrangement of several chips is created. In this case, the carrier structure would be another chip.

[0003] Various methods for mounting chips on a carrier structure are known from the state of the art: bonding with conductive or non-conductive adhesives, hot-air soldering, wave soldering, reflow soldering (melting solder balls), or wire bonding, to name just a few. Chips can be mounted using connecting wires (bonding wires) or directly, without additional connecting wires.

[0004] In so-called flip-chip assembly, for example, the unhoused chip is attached directly to a substrate using contact bumps, so-called "bumps," without any additional connecting wires. In this case, the chips are provided with a multitude of small solder balls arranged next to one another in a grid of columns and rows (BGA, Ball Grid Array). During assembly, the chips are placed on the substrate with the solder balls facing down. The solder balls are then wetted with a flux, and the assembly is heated so that the solder melts and creates an electrical connection between the contact pads of the chip and the contacts of the substrate (housing, package). This is also known as reflow soldering.

[0005] BGA technology enables particularly small dimensions between the chip and substrate and short conductor lengths. Bumps are now less than 100 µm in size. However, even smaller dimensions are desirable for special applications, particularly in mobile communications technology.

[0006] Document US 2017 / 0271299 A1 describes a bonding structure for a display panel. The bonding structure comprises an anisotropic conductive film made of resin and containing conductive particles, the film being sandwiched between two substrates. By applying an electric field, the particles are aligned between eclectic contacts of the substrates, and the resin is subsequently cured.

[0007] Document US 2017 / 0062379 A1 describes structures with an anisotropic conductive film and corresponding manufacturing processes. Substrates with the conductive film sandwiched between them are pressed together under high pressure and temperature.

[0008] Document US 2017 / 0062374 A1 describes an anisotropic conductive material, an electronic device comprising such a material, and a corresponding manufacturing method. The anisotropic material can comprise a matrix with particles in the form of capsules containing conductive material. To produce the electronic device, the anisotropic material is pressed between electrical contacts under high pressure.

[0009] MAO, J. et al., Thiol functionalized carbon nanotubes: Synthesis by sulfur chemistry and their multi-purpose applications. In: Appl. Surf. Sci., Vol. 447, 2018, pp. 235-243. - ISSN 0169-4332, describe the functionalization of carbon nanotubes.

[0010] Document JP 6 286 852 B2 describes conductive particles, anisotropic conductive particles and a process for their production.

[0011] The document KR 10 2009 0 063 361 A describes isolated, conductive particles and a process for producing an anisotropic conductive film using such particles.

[0012] ZHANG, R. et al., "Interfacial Design of Anisotropy Conductive Adhesive-Based Interconnects Using Molecular Wires and Understanding of Their Electrical Conduction." In: IEEE Transactions on Advanced Packaging, Vol. 33, 2010, pp. 892-898. - ISSN 1557-9980, describe the functionalization of multiple bonding partners with identical functional groups.

[0013] An object of the present invention is therefore to further reduce the distance between the chip and the carrier structure and to develop a method for producing corresponding electronic units.

[0014] This object is achieved according to the invention by the features specified in the independent claims. Further embodiments of the invention emerge from the subclaims.

[0015] The invention is set out and defined in independent claims 1, 8 and 12.

[0016] According to the invention, an electronic unit is proposed which comprises a first component with an integrated circuit and a plurality of first electrical contacts and a second component with a plurality of second electrical contacts. According to the invention, the first and second electrical contacts are electrically connected to one another via an electrically conductive structure comprising a plurality of electrically conductive particles which, due to their physical or chemical properties, form an agglomerate and bond to the first and second electrical contacts. The particles and / or electrical contacts are preferably provided with at least one functional group so that the particles bond preferentially to the electrical contacts. The use of conventional bonding technologies, such as soldering, gluing, or ultrasonic welding, is not required in this case.

[0017] The particles mentioned can be, for example, micro- or nanoparticles and have a wide variety of shapes, such as rod-shaped, spherical, star-shaped, or other geometries, etc.

[0018] According to a preferred embodiment of the invention, the particles are rod-shaped nanoparticles. In this case, the conductive structure comprises a plurality of nanoparticles aligned parallel in a predetermined direction and in contact with one another.

[0019] The particles are electrically conductive and preferably consist (at least partially) of a semi-metallic and / or metallic material, and / or polymer, ceramic and / or metals such as gold, silver, copper and / or bronze, tin, zinc, lead, tungsten, mercury or their alloys and / or have a metallic surface coating. Other materials are also conceivable, such as carbon nanotubes, graphene, graphite, semiconductors (silicon, germanium), fullerenes, polytetrafluoroethylene.

[0020] A surface coating of the particles can be achieved, for example, via functionalization with terminal reactive groups, in particular with polymers which have at least one thiol group, such as 11-mercaptoundecanoic acid or similar, or several thiol groups, such as dithiols, in particular 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, benzene-1,4-dithiol, 2,2'-ethylenedioxydiethanethiol, 1,6-hexanedithiol, tetra(ethylene glycol)dithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,11-undecanedithiol, hexa(ethylene glycol)dithiol, 1,16-hexadecanedithiol or similar. The functionalized particles bind selectively to metal particles, which accumulate along the surface of the functionalized particles and form the coating.

[0021] According to one embodiment of the invention, at least one of the following elements is functionalized, i.e., provided with at least one functional group: the particles, the first contacts, the second contacts. The functionalization achieves a selective bonding of the respective element to another substance. For example, functionalizing an element with a thiol group leads to increased bonding of the respective element to metallic surfaces.

[0022] In a first embodiment, for example, only the particles may be functionalized so that they adhere better to the metal surfaces of the first and second contacts. In another embodiment, the electrical contacts or both elements, namely the electrical contacts and the particles, may be functionalized.

[0023] The functionalization of metallic nanoparticles is known, for example, from WO2015 / 103028A1, CA2712306C, and US Pat. No. 8,790,552 B2. Thiol functionalizations are known, for example, from Kellon JE, Young SL, & Hutchison JE (2019), "Engineering the Nanoparticle-Electrode Interface," Chemistry of Materials, 31(8), 2685-2701, and from Kubackova J., et al. (2014), “Sensitive surface-enhanced Raman spectroscopy (SERS) detection of organochlorine pesticides by alkyl dithiol-functionalized metal nanoparticles-induced plasmonic hot spots”, Analytical chemistry 87.1, 663-669, also from Ahonen P., Laaksonen T., Nykänen A., Ruokolainen J., & Kontturi K. (2006), “Formation of stable ananoparticle aggregates induced by dithiol cross-linking”, The Journal of Physical Chemistry B, 110(26), 12954-12958 and from Dong TY, Huang C., Chen CP, & Lin MC(2007), „Molecular self-assembled monolayers of ruthenium (II)-terpyridine dithiol complex on gold electrode and nanoparticles“, Journal of Organometallic Chemistry, 692(23), 5147-5155, bekannt.

[0024] Depending on the application, there are various suitable functional groups, such as: B.: Alkanes, cycloalkanes, alkenes, alkynes, phenyl substituents, benzyl substituents, vinyl, allyl, carbenes, alkyl halides, phenol, ethers, epoxides, ethers, peroxides, ozonides, aldehydes, hydrates, imines, oximes, hydrazones, semicarbazones, hemiacetals, hemiketals, lactols, acetal / ketal, Aminals, carboxylic acid, carboxylic acid esters, lactones, orthoesters, anhydrides, imides, carboxylic acid halides, carboxyl groups, carboxylic acid derivatives, amides, lactams, peroxyacids, nitriles, carbamates, hydrogen, guanidines, carbodiimides, amines, aniline, hydroxylamines, hydrazines, hydrazones, azo compounds, nitro compounds, thiols, mercaptans, Sulphides, phosphines, P-ylenes, P-ylides, Biotin, streptavidin, metallocenes, or the like, which bind with different strengths or bind to different partners.

[0025] According to a preferred embodiment of the invention, one of the aforementioned elements (e.g., the particles) is functionalized with a carboxyl group, and another element (e.g., the electrical contacts) is functionalized with primary amines. The carboxyl group is preferably activated with EDC / NHS, causing the two elements (particles and electrical contacts) to form a covalent bond. Subsequently, the remaining functional groups are blocked with ethanolamine.

[0026] According to another embodiment of the invention, one of the aforementioned elements (e.g., the particles) is functionalized with a thiol group; the other element (e.g., the electrical contacts) is not functionalized. In this case, selective bonding between the elements occurs via weak interactions.

[0027] The particles and electrical contacts can each be functionalized with one or more identical or different functional groups.

[0028] The particles are preferably capable of self-aligning in a specific direction. This self-alignment property can be achieved, for example, by thiol groups and / or Janus (nano)particles and / or patchy particles and / or by magnetism (particle and surface are magnetic) and / or via electrostatic interaction. Such interactions can be achieved, for example, by a positively charged or negatively charged surface and / or via weak interactions and / or via chemical reaction(s) such as click chemistry (e.g., thiol-ene click chemistry), Michael reaction, or the like.

[0029] The first component mentioned above can be, for example, a packaged (enclosed) chip, a die, or an electronic system with multiple chips and possibly other components (with or without a housing). The second component can be, for example, a housing, a chip, a circuit board, or another substrate.

[0030] According to a specific embodiment of the invention, the first component is a die and the second component is a circuit board, a chip package or another substrate.

[0031] According to one embodiment of the invention, the first and / or second component comprises one or more spacers dimensioned such that opposing contact surfaces of the first and second contacts are spaced apart. The spacing can be, for example, a few µm, e.g., 20 µm, or even in the nm range, e.g., 100 nm or less.

[0032] The contacts of the first and / or second component preferably have a flat contact surface, but they can also have a spherical, concave, or convex surface. A concave contact surface is particularly advantageous when capsules containing the conductive particles are applied to the electrical contacts. The contacts of a component are preferably located in the same plane.

[0033] The electrically conductive structure made of electrically conductive particles mentioned above can be produced using various processes. According to a first variant proposed here, a suspension in which the particles are suspended is applied directly to at least one of the components. According to a second variant, a suspension with capsules containing the electrically conductive particles is applied to at least one of the components. Alternatively, the capsules can also be applied as a powder.

[0034] With regard to the first variant, the invention relates to a method for producing an electronic unit with a first component having an integrated circuit and a plurality of first electrical contacts, and a second component having a plurality of second electrical contacts, wherein at least the following steps are carried out: - producing a suspension containing particles as suspended matter, - applying the suspension to at least one of the components so that an electrically conductive structure comprising one or more of the electrically conductive particles is formed on the electrical contacts of the at least one component, - arranging the first and second components at a predetermined distance, with opposing first and second contacts, wherein the application of the suspension can take place before or after the arranging of the first and second components; and - Washing away the electrically conductive particles that are not bound to the electrical contacts.

[0035] At least one of the following elements is preferably provided with one or more functional groups, as already described: the particles, the first contacts, the second contacts.

[0036] The above-mentioned suspension comprises a solvent as a base substance with at least one of the following substances: water, ethanol.

[0037] After applying the suspension to at least one of the components, a drying step is preferably carried out in which the at least one component is dried.

[0038] The electronics unit can also be briefly heated above the melting point of the particles contained in the electrically conductive structure. Heating the unit can be carried out, for example, in a reflow oven at temperatures between 40°C and 250°C. This melts the individual particles and forms a solid, conductive body that electrically and mechanically connects the opposing contacts. Alternatively or additionally, the particles and / or the underfill can be released and / or crosslinked through the reflow process.

[0039] Finally, an electrically insulating material can be applied to at least one of the components, whereby the application of the electrically insulating material can take place before or after the two components are joined. In electronics manufacturing, particularly in flip-chip assembly, the electrically insulating material is also referred to as underfill. The main reason for using underfill is the different thermal expansion coefficient between the silicon chip and the substrate. Without underfill, a temperature change can place very high stress on the chip-to-substrate connection, leading to fatigue and cracking. The underfill also serves to prevent short circuits.

[0040] An adhesive, in particular an epoxy resin or a PU adhesive or an acrylate adhesive, can be used as an underfill or electrically insulating material.

[0041] According to the second variant, nano- and / or microcapsules containing the electrically conductive particles are applied to at least one of the components. This encapsulation makes it possible to provide a defined mass or volume of particles or other substances at a specific location and to release them in a targeted manner via an activation mechanism.

[0042] With regard to the second variant, the invention relates to a method for producing an electronic unit with a first component having a plurality of first electrical contacts, which comprises an integrated circuit, and a second component having a plurality of second electrical contacts, wherein at least the following steps are carried out: - Production of capsules each containing one or more electrically conductive particles, - Applying the capsules to at least one of the components (e.g. as a suspension or powder), - arranging the first and second components at a predetermined distance, with opposite first and second contacts, wherein the application of the suspension can take place before or after the arranging of the first and second components; - activating the capsules so that the electrically conductive particles are released and arrange themselves on the electrical contacts of the at least one component and form an electrically conductive structure comprising a single or a plurality of the electrically conductive particles.

[0043] According to a preferred embodiment of the invention, a suspension is prepared in which the capsules are present as suspended matter. The suspension is then applied to one or both components. Alternatively, the capsules can also be applied to the component(s) as a powder or paste, additionally with the aid of a stencil.

[0044] A wide variety of processes for producing nano- or microcapsules are known from the state of the art. For example, it is possible to produce capsules by solvent evaporation, thermal gelation, gel formation, interfacial polycondensation, polymerization, spray drying, fluidized bed, droplet freezing, extrusion, supercritical fluid, coacervation, air suspension, pan coating, co-extrusion, solvent extraction, molecular entrapment, spray crystallization, phase separation, emulsion, in situ polymerization, interfacial deposition, emulsification with a nanomolar sieve, ionotropic gelation method, coacervation phase separation, matrix polymerization, interfacial crosslinking, congealing method, centrifugal extrusion, and / or one or more other processes.

[0045] The shell of the capsules containing the electrically conductive particles is preferably functionalized so that the capsules bind particularly strongly to the metal surface of the electrical contacts. Alternatively or additionally, the electrical contacts and, if necessary, the particles themselves can also be functionalized.

[0046] According to one embodiment of the invention, the capsules containing the particles therein are functionalized with one or more thiol groups; the electrical contacts are preferably not functionalized. Regarding the functionalization of the capsules, the same applies as previously stated regarding the functionalized particles.

[0047] The shell of the microcapsule or a coating on the surface of the microcapsules can contain, among other substances, the following: E.g. with albumin, gelatin, collagen, agarose, chitosan, starch, carrageenan, polystarch, polydextran, lactides, glycolides and copolymers, polyalkyl cyanoacrylate, polyanhydride, polyethyl methacrylate, acrolein, glycidyl methacrylate, epoxy polymers, gum arabic, polyvinyl alcohol, methylcellulose, metal, metal nanoparticles, carboxymethylcellulose, hydroxyethylcellulose, arabinogalactan, polyacrylic acid, ethylcellulose, polyethylene, polymethacrylate, polyamide (nylon), polyethylene vinyl acetate, cellulose nitrate, silicones, poly(lactide-co-glycolide), paraffin, carnauba, spermaceti, beeswax, stearic acid, stearyl alcohols, glycerol stearate, shellac, cellulose acetate phthalate, zein, hydrogels or the like.

[0048] To release the substances contained in the capsules, they are opened at a specific time. This is also referred to as "activation." Activation can occur, for example, through a change in pressure, pH value, UV radiation, osmosis, temperature, light intensity, humidity, ultrasound, induction, or similar. This allows the time at which the substances contained in the capsules are released to be precisely controlled.

[0049] According to the invention, the capsules are preferably activated after the first and second components have been combined.

[0050] Capsules that can be used include, for example, simple shell-core capsules, capsules with cationic or anionic character, capsules with multiple shells or multiple layers of the shell material (so-called multilayer microcapsules), and granules.

[0051] The capsules can be individual capsules or part of a multi-capsule system consisting of several interconnected capsules. With a multi-capsule system, such as a two-component capsule system (2K capsule system), it is possible to release different substances in a defined amount or ratio.

[0052] The individual capsules of a multi-capsule system can be the same or different. They can differ, for example, in their shell material, shell thickness, size, or activation mechanism.

[0053] For example, US 2012 / 0107601 A1 discloses a capsule system that reacts to pressure and releases liquids accordingly. Further capsule systems are known from WO 2017 / 192407 A1, US 8 747 999 B2, WO 2017 042709 A1, WO 2016 / 049308 A1, and WO 2018 / 028058 A1.

[0054] According to a preferred embodiment of the invention, the electrically conductive particles are contained in first capsules, each of which is in turn connected to at least one second capsule. The second capsules can be empty or contain, for example, an electrically insulating material (underfill) or another desired material.

[0055] Alternatively, individual capsules that are not connected to other capsules can also be used. According to one embodiment of the invention, a first group of capsules is provided, which contain electrically conductive particles, and a second group of capsules is provided, which contain a second material, in particular an underfill. The two groups can be applied to the component(s) of the electronic unit simultaneously or sequentially.

[0056] The size of the first capsules preferably corresponds approximately to the size of the electrical contacts in one dimension (e.g. the length or width of the contacts in the case of rectangular contact surfaces).

[0057] According to a preferred embodiment of the invention, the size of the second capsules corresponds approximately to the size of a distance between two adjacent electrical contacts of the same component.

[0058] The first and second capsules are preferably activated one after the other. However, they can also be activated simultaneously.

[0059] At least one of the capsules of a multiple capsule system is preferably functionalized. Optionally or additionally, the first contacts and / or the second contacts can also be functionalized. According to a preferred embodiment of the invention, the first capsules, which contain the electrically conductive particles, are functionalized with one or more functional groups. The second capsules, which contain the electrically insulating material, are preferably not functionalized.

[0060] A functional group can, in principle, be linked to the respective element directly or via a so-called linker. The choice of linker essentially determines the distance between the functionalized element (particle and / or electrical contact and / or capsule) and a second element to which the functionalized element selectively binds.Possible linkers include, for example, biopolymers, proteins, silk, polysaccharides, cellulose, starch, chitin, nucleic acid, synthetic polymers, homopolymers, DNA, halogens, polyethylene, polypropylene, polyvinyl chloride, polylactam, natural rubber, polyisoprene, copolymers, statistical copolymers, gradient copolymers, alternating copolymers, block copolymers, graft copolymers, acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), butyl rubber, polymer blends, polymer alloys, inorganic polymers, polysiloxanes, polyphosphates, polysilazanes, ceramics, basalt, isotactic polymers, syndiodactic polymers, atactic polymers, linear polymers, cross-linked polymers, elastomers, thermoplastic elastomers, thermosets, semi-crystalline linkers, thermoplastics, cis-trans polymers, conductive polymers, supramolecular polymers. Short description of the drawings

[0061] The invention is explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 an electronic unit with two components which are electrically connected to one another via an electrically conductive structure consisting of a plurality of electrically conductive particles; Fig. 2 the electronic unit of Fig. 1 with an additional underfill; Fig. 3 an electronic unit with two components and additional spacers; Fig. 4-10 different states of a method for producing an electronic unit with two electronic components, in which a suspension in which electrically conductive particles are present as suspended matter is applied to one of the components before both components are joined together; Fig. 11-15 show various states of a method for producing an electronic unit with two electronic components, in which a suspension containing electrically conductive particles as suspended matter is applied to both components of the electronic unit after the components have been joined together; Fig. 16-21 different states of a method for producing an electronic unit with two electronic components, in which a suspension in which the particles are located in capsules is applied to one of the components before both components are joined together. Embodiments of the invention

[0062] Fig. 1 shows an electronic unit 1 with two components 2, 4, which are electrically connected to one another via an electrically conductive structure 8 consisting of a plurality of electrically conductive particles 9.

[0063] The first component 2 comprises an integrated circuit 6 and can be, for example, a die or a packaged chip having a plurality of adjacently arranged electrical contacts 3 on one surface. The second component 4 can be, for example, a chip housing, another chip, a printed circuit board, or any other substrate 7, which also has a plurality of spaced-apart electrical contacts 5.

[0064] The electrically conductive particles 9 are preferably micro- or nanoparticles, which may consist, for example, of gold, silver, copper, tin, zinc, or various alloys; or of a base metal with a contact surface made of another metal. In the illustrated embodiment, the particles are rod-shaped nanoparticles that are aligned parallel, side by side, in a predetermined direction, while being in contact with one another.

[0065] Due to the small size of the particles 9, the distance between the opposite contacts 3, 5 of a contact pair is particularly small and can be, for example, 500 nm or less.

[0066] The electrically conductive particles 9 and / or the contacts 3 or 5 are preferably functionalized so that the particles 9 preferably connect to the electrical contacts 3, 5.

[0067] Fig. 2 shows the arrangement of Fig. 1, wherein an electrically insulating material 11—the so-called underfill—is additionally present in a gap 10 between adjacent contact pairs 3, 5. The underfill can be, for example, an epoxy resin, a PU adhesive, or an acrylate adhesive, plastic, or polymer.

[0068] Fig. Figure 3 shows an alternative embodiment of the electronic unit 1, in which each component 2, 4 comprises a spacer 12, which is dimensioned such that the opposing contact surfaces of the contacts 3, 5, when the two components 2, 4 are joined together, occupy a predetermined distance from each other. In the illustrated embodiment, the spacers are realized as projections that protrude outwardly from the components 2, 4 and are made of a non-conductive material. Furthermore, the Fig. 2 shown electronic unit 1 is constructed identically to the electronic unit 1 of Fig. 1, so reference is made to the description there.

[0069] The Fig. 4 to 10 show different states of a method for producing an electronic unit 1, in which a suspension 13, in which electrically conductive particles 9 are present as suspended matter, is applied to one of the components 2, 4 before the two components 2, 4 are joined together.

[0070] The particles 9 are functionalized with a thiol group and therefore bind selectively with the metal surfaces of the electrical contacts 5. In addition, the electrical contacts 5 can also be functionalized and have one or more functional groups.

[0071] In Fig. 4 shows how a suspension 13, in which the electrically conductive particles 9 are located, is poured from a vessel 14 onto the second component 4.

[0072] Fig. Figure 5 shows a state in the manufacturing process in which the electrically conductive particles 9 accumulate on the metal surfaces of the second electrical contacts 5 due to their functionalization. In the spaces 10 between adjacent electrical contacts 5, however, the binding effect is less strong or nonexistent, so that fewer conductive particles 9 are present there.

[0073] Fig. Figure 6 shows an exemplary further embodiment in which both the electrically conductive particles 9 and the second electrical contacts 5 are functionalized. Here, the electrically conductive particles 9 comprise a first functional group R1, such as a carboxyl group, and the electrical contacts 5 comprise a second functional group R2, such as primary amines. The two functional groups R1, R2, in turn, selectively bind to one another particularly strongly, so that the desired agglomeration of electrically conductive particles 9 on the electrical contacts 5 occurs.

[0074] Fig. 7 shows a further method step in which the electrically conductive particles 9 that do not adhere to the surface of the second component 4 are washed off using a washing liquid 15. Water, ethanol, or a mixture thereof can be used as the washing liquid 15, for example. Alternatively, compressed air or another fluid could be used for the washing process. The washing off of the non-bonded conductive particles 9 preferably takes place in a fluid flow. With regard to the flow velocity of the fluid, care must be taken to ensure that it is not too high to prevent the particles 9 arranged on the electrical contacts 5 from being accidentally detached.

[0075] In Fig. 8, the two electronic components 2, 4 are joined together with opposite contacts 3, 5 so that they are electrically connected via the agglomerate of electrically conductive particles 19.

[0076] Fig. Figure 9 shows the application of an underfill 11 into the spaces 10 between adjacent contact pairs 3, 5 of the electronics unit 1. The underfill can, as is known from electronics manufacturing, be applied, for example, by means of a dosing device at the edge area of ​​the electronics unit 1 and then flows into the spaces 10 of the electronics unit 1 due to capillary effects until they are filled with the underfill 11. The underfill can, for example, be an adhesive such as an epoxy resin or another electrically insulating material. The result is a very compact electronics unit 1, as shown in Fig. 10 is shown.

[0077] The Fig. 11 to 15 show different states of a method for producing an electronic unit 1, in which electrically conductive particles 9 are applied in the form of a suspension 13 after the two components 2, 4 have been joined together.

[0078] Fig. 11 shows an electronic unit 1 with two electrical components 2, 4, each having a plurality of planar contacts 3, 5. The components 2, 4 are arranged with opposing electrical contacts 3, 5, with the first electrical contacts 3 and the second electrical contacts 5 touching each other. In the illustrated embodiment, the first and second electrical contacts 3, 5 each have a section that protrudes beyond the remaining contact surface and serves as a spacer 12. The remaining contact surfaces are spaced apart from one another.

[0079] After joining the components 2, 4, a suspension 13 is applied, in which the electrically conductive particles 9 are contained as suspended matter. This is shown in Fig. 12 shown.

[0080] The electrically conductive particles 9 are functionalized by means of a thiol group and therefore preferentially attach to the metal surface of the electrical contacts 3, 5. The remaining free space between the opposite contact surfaces of the electrical contacts 3, 5 is filled with electrically conductive particles 9, as shown in Fig. 13 is shown.

[0081] Fig. Figure 14 shows a process step in which electrically conductive particles 9 that are not bound to a metal surface are washed off using a washing liquid 15. As previously described, the washing solution may contain water, ethanol, or another fluid.

[0082] In Fig. 15 is finally added an underfill 11, as described above with regard to Fig. 10 has already been described.

[0083] The Fig. 16 to 21 finally show different states of a method for producing an electronic unit 1, in which the electrically conductive particles 9 are applied in the form of capsules K.

[0084] In the illustrated embodiment, double capsules are used, comprising a first capsule K1 and a second capsule K2, which are connected to one another. The first capsule K1 contains the electrically conductive particles 9; the second capsule K2 contains an electrically insulating material 11 or the underfill. The capsules K can be produced using a known process, as described above. A connection between two capsules K1, K2 to form a double capsule can be achieved, for example, by functionalization, as also described in the general part of the description.

[0085] Fig. Figure 16 first shows the application of a suspension 13 with a plurality of double capsules 17, which are contained in the suspension 13 as suspended matter. In this case, the suspension 13 is simply poured onto the surface of the second electronic component 4, causing the double capsules 17 to be evenly distributed over the surface. The first capsules K1, which contain the nanoparticles, are functionalized with a thiol group and therefore bind particularly strongly to the metal surfaces of the second contacts 5.

[0086] The size of the first capsules K1 corresponds approximately to the size of the contact surface of the electrical contacts 5. The size of the second capsules K2, on the other hand, corresponds approximately to the distance 10 between two adjacent electrical contacts 5. The second capsules K2 are not functionalized. After applying the suspension 13 to the surface of the second component 4, the double capsules 17 are arranged as shown in the Fig. 17 and Fig. 18. A first capsule K1 is located on each contact surface of an electrical contact 5; the second capsules K2 essentially fill the space between adjacent electrical contacts 5.

[0087] In a next process step, the first electronic component 2 is placed on the second component 4 so that the contact surfaces of the first and second components 2, 4 are opposite each other at a predetermined distance (see Fig. 19, arrow B). The desired distance between the components 2, 4 is again achieved by spacers 12 (not shown).

[0088] Next, the first capsules K1 are activated by increasing the temperature, releasing the nanoparticles 9 contained therein. The nanoparticles 9 are functionalized with a thiol group, allowing them to selectively bind to the metal surface of the first and second contacts 3, 5. Optionally or additionally, the electrical contacts 3, 5 can also be functionalized.

[0089] In the next step, the second capsules K2 are activated (see Fig. 20), so that they release the underfill 11 contained therein. The delayed activation of the second capsules K2 can be achieved, for example, by the second capsules K2 having a thicker shell. Alternatively, this could also be achieved by a further increase in temperature or pressure, or in another known manner. The underfill 11 then spreads into the spaces between the electrical contacts 3, 5 and firmly bonds the two components 2, 4 together, as shown in Fig. 20. The finished electronic unit 1 is shown in Fig. 21 shown.

[0090] By contacting the first and second contacts 3, 5 using micro- or nanoparticles 9, a very low packing density and a correspondingly small and compact electronic unit 1 can be produced. Furthermore, this process is particularly simple and cost-effective.

Claims

[1] Electronic unit (1), comprising: • a first component (2) with a plurality of first electrical contacts (3) having an integrated circuit (6), and • a second component (4) with a plurality of second electrical contacts (5), wherein the first electrical contacts (3) and the second electrical contacts (5) are each electrically connected to one another via an electrically conductive structure (8) which has a plurality of electrically conductive particles (9), characterized by , that the particles (9) are functionalized with a first functional group (R1), and that the first contacts (3) and / or the second contacts (5) are functionalized with a second functional group (R2) different from the first functional group (R1). [2] Electronic unit (1) according to claim 1, characterized by that the particles (9) are micro- or nanoparticles. [3] Electronic unit (1) according to claim 1 or 2, characterized by that the particles (9) are rod-shaped nanoparticles which are aligned parallel in a given direction and are in direct contact with each other. [4] Electronic unit (1) according to one of the preceding claims, characterized by that the second component (4) is a housing, a chip, a printed circuit board or another substrate (7). [5] Electronic unit (1) according to one of the preceding claims, characterized by that the first component (2) is an unhoused chip. [6] Electronic unit (1) according to one of the preceding claims, characterized by that at least the first or second component (2, 4) has spacers (12) which are dimensioned such that opposite contact surfaces of the first and second contacts (3, 5) are at a distance from one another when both components (2, 4) are joined together. [7] Electronic unit (1) according to one of the preceding claims, characterized by that the contacts (3, 5) of the first and second components (2, 4) each lie in one plane. [8] Method for producing an electronic unit (1) with a first component (2) having an integrated circuit (6) and a plurality of first electrical contacts (3), and a second component (4) having a plurality of second electrical contacts (5), the method comprising the steps: - providing a suspension (13) in which particles (9) are contained as suspended matter, - functionalizing the particles (9) with a first functional group (R1), functionalizing the first contacts (3) and / or the second contacts (5) with a second functional group (R2) different from the first functional group (R1); - applying the suspension (13) to at least one of the components (2, 4) so ​​that an electrically conductive structure (8) is formed on the electrical contacts (3, 5) of the at least one component (2, 4), said structure having one or more of the electrically conductive particles (9), - arranging the first and second components (2, 4) at a predetermined distance, with opposite first and second contacts (3, 5), wherein the application of the suspension (13) takes place before or after the arranging of the first and second components (2, 4); and - washing the electrically conductive particles (9) from a surface of the at least one component (2, 4) which is not covered by electrical contacts (3, 5). [9] Method for producing an electronic unit (1) according to claim 8, characterized by that the suspension contains at least one of the following substances: water, ethanol. [10] Method for producing an electronic unit (1) according to one of claims 8 to 9, characterized by that after the suspension (13) has been applied to at least one of the components (2, 4), a drying step is carried out in which the at least one component (2, 4) is dried. [11] Method for producing an electronic unit (1) according to one of claims 8 to 10, characterized by that after the production of the electrically conductive structure (8), an electrically insulating material (11) is applied to at least one of the components (2, 4), wherein the application of the electrically insulating material (11) takes place before or after the arrangement of the two components (2, 4). [12] Method for producing an electronic unit (1) with a first component (2) having a plurality of first electrical contacts (3) which has an integrated circuit (6), and a second component (4) having a plurality of second electrical contacts (5), the method comprising the steps: - Providing capsules (K) each containing one or more electrically conductive particles (9), - applying the capsules (K) to at least one of the components (2, 4), - arranging the first and second components (2, 4) at a predetermined distance, with opposite first and second contacts (3, 5), wherein the application of the capsules (K) takes place before or after the arranging of the first and second components (2, 4); - activating the capsules (K) so that the electrically conductive particles (9) are released and are arranged on the electrical contacts (3, 5) of the at least one component (2, 4) and form an electrically conductive structure (8) which has one or more of the electrically conductive particles (9); wherein the first capsules (K1) are functionalized with a first functional group (R1), and wherein the first contacts (3) and / or the second contacts (5) are functionalized with a second functional group (R2) different from the first functional group (R1). [13] Method for producing an electronic unit (1) according to claim 12, characterized by that the capsules (K) are activated after the first and second components (2, 4) have been arranged with opposite first and second contacts (3, 5). [14] Method for producing an electronic unit (1) according to claim 12 or 13, characterized by that the electrically conductive particles (9) are contained in first capsules (K1) and the first capsules (K1) are each connected to at least one second capsule (K2) which has an electrically insulating material (11), and that the capsules (K1, K2) are applied to at least one of the components (2, 4). [15] Method for producing an electronic unit (1) according to one of claims 12 to 14, characterized by that the size of the first capsules (K1) corresponds approximately to the size of the electrical contacts (3, 5) in one dimension. [16] Method for producing an electronic unit (1) according to one of claims 12 to 15, characterized by that the size of the second capsules (K2) corresponds approximately to the size of a distance between two adjacent electrical contacts (3, 5) of the same component (2, 4). [17] Method for producing an electronic unit (1) according to one of claims 12 to 16, characterized bythat the first and second capsules (K1, K2) are activated one after the other. [18] Electronic unit (19) manufactured by a method according to one of claims 8 to 11 or by a method according to one of claims 12 to 17.

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