Substrate arrangement, method for producing an electronic component, and electronic component

Abstract

This invention relates to a substrate arrangement, a method for manufacturing an electronic component, and an electronic component. The substrate arrangement includes: (a) a metal foil comprising an upper metal foil side and a lower metal foil side, wherein the metal foil includes a copper layer having an upper copper layer side and a lower copper layer side, wherein the upper metal foil side is formed by the upper copper layer side; and (b) a contact layer disposed on the lower metal foil side, wherein the upper copper layer side has an oxygen content in the range of 10 atomic percent to 30 atomic percent.

Description

[0001] This invention relates to a substrate arrangement, a method for manufacturing electronic components, and an electronic component.

[0002] In order to produce electronic components, in the field of power electronics, base substrates, especially metal-ceramic substrates or lead frames, are typically filled with electronic components, especially semiconductor devices.

[0003] The area requiring conductive contact with an unfilled region of the base substrate is located on the upper side of the electronic component, opposite to the base substrate. This contact is typically achieved using bonding wires, where one end of the bonding wire is integrally bonded to the upper region of the electronic component, and the other end is integrally bonded to the unfilled region of the base substrate. Aluminum bonding wires can be integrally bonded to a metal, particularly copper, in the base substrate. Aluminum bonding wires can also be integrally bonded to the electronic component, for example, via a silver-containing layer, typically located on the upper side of the electronic component. However, aluminum bonding wires have the disadvantage of low electrical conductivity. Furthermore, it has been found that electrical contact between the electronic component and the base substrate via aluminum bonding wires results in insufficient reliability and reduced functionality.

[0004] For this reason, copper bonding leads are needed instead of aluminum bonding leads. Copper has a much higher electrical conductivity than aluminum. Furthermore, copper bonding leads can be bonded particularly reliably to the metal, especially copper, of the base substrate in a monolithic manner. However, copper bonding leads cannot be easily bonded monolithically to the top of electronic components.

[0005] In the prior art, it is therefore proposed that the bonding leads made of copper are not directly connected to the upper side of the electronic component. Instead, a substrate arrangement is provided having a metal foil and a contact layer (e.g., pre-dried sintering paste). The metal foil has an upper side and a lower side, wherein the lower side of the metal foil is bonded to the entire surface of the contact layer. Finally, the metal foil of the substrate arrangement is integrally bonded to the upper side of the electronic component via the contact layer, such that the upper side of the metal foil can be used for an integrally bonded connection with the copper bonding leads.

[0006] Therefore, the method consists of a substrate arrangement with a metal foil, the upper side of which can be bonded to the copper bonding leads in a particularly stable manner and with consistent high quality.

[0007] Therefore, the object of the present invention is preferably to provide a substrate arrangement having a metal foil, the upper side of which can be bonded to copper bonding leads in a particularly stable manner and with consistent high quality.

[0008] This objective is achieved by the substrate arrangement as described in claim 1.

[0009] Therefore, the present invention provides a substrate arrangement comprising:

[0010] (a) A metal foil comprising an upper side and a lower side, wherein the metal foil includes a copper layer having an upper side and a lower side, wherein the upper side of the metal foil is formed by the upper side of the copper layer, and

[0011] (b) A contact layer disposed on the underside of the metal foil.

[0012] The characteristic feature is that the upper side of the copper layer has an oxygen content in the range of 10 atomic percent to 30 atomic percent.

[0013] The present invention also provides a method for producing electronic components and an electronic part.

[0014] This invention relates to a substrate arrangement.

[0015] Electrical contact between the upper side of the electronic component and the unfilled area of ​​the base substrate can preferably be fabricated using a substrate arrangement. For this purpose, a metal foil is integrally bonded to the upper side of the electronic component via a contact layer. The metal foil in this case provides a surface suitable for forming a reliable, integrally bonded connection with one end of a bonding lead, particularly a copper bonding lead. The other end of the bonding lead can be connected to the unfilled area of ​​the base substrate, thereby creating an electrical contact between the upper side of the electronic component and the unfilled area of ​​the base substrate via the metal foil and the bonding lead.

[0016] The substrate arrangement includes a metal foil.

[0017] The metal foil includes an upper side and a lower side. A contact layer is disposed on the lower side of the metal foil. In this case, the lower side of the metal foil is at least partially connected to the contact layer in a planar manner. Therefore, the lower side of the metal foil is preferably the surface of the metal foil with the largest surface area, which is at least partially connected to the contact layer in a planar manner. Therefore, the upper side of the metal foil is preferably the side of the metal foil facing away from the contact layer. Thus, the upper side of the metal foil is the side opposite to the lower side of the metal foil.

[0018] According to a preferred embodiment, the upper side of the metal foil is not integrally bonded to the solid substrate. The solid substrate is preferably a solid substrate at 25°C and normal pressure. Preferably, the upper side of the metal foil is not integrally bonded to the insulating material layer. Particularly preferably, the upper side of the metal foil is not integrally bonded to the ceramic layer.

[0019] According to another preferred embodiment, based on the total surface area of ​​the upper side of the metal foil, less than 20%, more preferably less than 10%, even more preferably less than 5%, most preferably less than 1%, and particularly less than 0.1% of the upper side of the metal foil is inseparably bonded to the solid body. Inseparable bonding preferably means that releasing the bond is impossible, or would result in at least partial damage to the upper side of the metal foil, or at least functional impairment. The solid body may be a solid body comprising insulating material, particularly a ceramic body.

[0020] According to another preferred embodiment, the upper side of the metal foil may be connected to a bonding lead, preferably a bonding lead containing at least 50% by weight of copper.

[0021] The metal foil preferably has a thickness d(Me). The thickness d(Me) of the metal foil is preferably in the range of 5µm to 500µm, particularly preferably in the range of 10µm to 200µm, and very particularly preferably in the range of 20µm to 150µm.

[0022] The metal foil includes a copper layer.

[0023] The copper layer is preferably formed of copper foil. Based on the total weight of the copper layer, the copper layer preferably contains at least 99.5% by weight of copper, particularly preferably at least 99.95% by weight of copper, and very particularly preferably at least 99.995% by weight of copper.

[0024] The copper layer has an upper copper layer and a lower copper layer. The upper side of the metal foil is formed by the upper copper layer. The lower copper layer can be connected to another layer.

[0025] The metal foil can be composed of a copper layer. In this case, the underside of the metal foil can be formed from the underside of the copper layer.

[0026] The upper side of the copper layer has an oxygen content in the range of 10 atomic percent to 30 atomic percent. Preferably, the upper side of the copper layer has an oxygen content in the range of 12 atomic percent to 28 atomic percent, and particularly preferably in the range of 15 atomic percent to 25 atomic percent.

[0027] According to a preferred embodiment, the upper side of the copper layer has a carbon content in the range of 30 atomic percent to 60 atomic percent. Preferably, the upper side of the copper layer has a carbon content in the range of 35 atomic percent to 55 atomic percent, and particularly preferably in the range of 40 atomic percent to 50 atomic percent.

[0028] According to a preferred embodiment, the upper side of the copper layer is designed such that, in depth distribution measurements after a sputtering time of up to 300 s (sputtering rate: 1.0 nm / min for reference tantalum pentoxide; ion source: xenon ions, accelerating voltage: 4 kV), the exposed upper side of the copper layer has an oxygen content of less than 1.0 atomic percent.

[0029] According to another preferred embodiment, the upper side of the copper layer is designed such that, in depth distribution measurements after a sputtering time of 180 s (sputtering rate: 1.0 nm / min for reference tantalum pentoxide; ion source: xenon ions, accelerating voltage: 4 kV), the exposed upper side of the copper layer has an oxygen content of less than 1.0 atomic percent.

[0030] The content of copper, carbon, and oxygen on the upper side of the copper layer is preferably determined by Auger electron spectroscopy. The measurement is preferably performed using a PHI 5800 MultiTechnique ESCA system (Physical Electronics, Inc., USA). The sample of the substrate arrangement to be measured is preferably first stored in a moisture-proof bag under a nitrogen atmosphere. For this purpose, after sampling, the sample is transferred to the moisture-proof bag and rinsed twice with nitrogen gas of 4N purity. The bag is then sealed by soldering. The moisture-proof bag is opened just before the measurement, and the sample contained therein is then placed in the measurement chamber of the PHI 5800 MultiTechnique ESCA system. In the measurement chamber, the content of copper, carbon, and oxygen on the upper side of the copper layer is measured using Auger electron spectroscopy. The PHI 5800 MultiTechnique ESCA system is also preferably used for depth distribution measurements. For this purpose, the upper side of the copper layer of the sample is sputtered for a defined time (e.g., 300 s or 180 s), and the content of copper, carbon, and oxygen on the upper side of the copper layer exposed by sputtering is measured using Auger electron spectroscopy. Sputtering is preferably performed using an ion gun (with xenon ions as the ion source) operating at a sputtering rate of 1.0 nm / min relative to a reference tantalum pentoxide using an accelerating voltage of 4 kV. The analytical parameters for Auger electron spectroscopy are preferably 5 kV, a beam current of 15 nA, and a measurement spot size of 100 × 100 μm. The signal obtained by Auger electron spectroscopy is preferably estimated using software (PHI MultiPak Version 9.9 (Physical Electronics, Inc., USA)). The given value is preferably the average of five measurements from different regions of the substrate arrangement.

[0031] According to a preferred embodiment, the metal foil includes an adhesion-promoting layer.

[0032] The adhesion promoting layer is preferably a layer that enables or promotes the adhesion of the contact layer to the underside of the metal foil. The adhesion promoting layer is preferably a layer that enables or promotes the formation of an integral connection between the substrate arrangement (particularly the underside of the metal foil of the substrate arrangement) and the upper side of the electronic component via the contact layer.

[0033] The adhesion promoting layer preferably has a thickness in the range of 20 nm to 1,500 nm, particularly preferably in the range of 30 nm to 100 nm, and very particularly preferably in the range of 50 nm to 500 nm.

[0034] The adhesion promoting layer preferably has an upper adhesion promoting layer side and a lower adhesion promoting layer side. The upper adhesion promoting layer side is preferably integrally bonded to the lower copper layer side. The upper adhesion promoting layer side is preferably connected to the lower copper layer side in a planar manner. Preferably, a contact layer is disposed on the lower adhesion promoting layer side.

[0035] The adhesion-promoting layer preferably comprises a precious metal or a precious metal alloy. The precious metal is preferably selected from the group consisting of gold, silver, and palladium. The precious metal alloy is preferably an alloy containing at least one precious metal and at least one non-precious metal. The precious metal in the precious metal alloy is preferably selected from the group consisting of gold, silver, and palladium. The non-precious metal in the precious metal alloy is preferably nickel. The precious metal alloy is preferably selected from the group consisting of nickel-gold alloys, nickel-silver alloys, and nickel-palladium-gold alloys.

[0036] According to a particularly preferred embodiment, the adhesion-promoting layer is multilayered. The multilayer embodiment provides, for example, a nickel layer in contact with the underside of the copper layer, a palladium layer in contact with the nickel layer, and a gold layer in contact with the palladium layer.

[0037] Adhesion-promoting layers can be produced, for example, by chemical (e.g., electrochemical) or physical deposition, particularly on the underside of a copper layer. Chemical deposition can be performed, for example, by electrochemical means or without the presence of an external current.

[0038] According to another preferred embodiment, the metal foil has at least one through-hole. The through-hole is preferably understood as a recess in the material of the metal foil extending from a first opening on the upper side of the metal foil to a second opening on the lower side. The openings can have different sizes and geometries. Preferably, the metal foil has multiple through-holes. The through-holes can be, for example, cylindrical, circular, rectangular, oval, elliptical, or rectangular with rounded corners. The presence of the through-holes can be particularly advantageous if the substrate arrangement includes a pre-fixing layer containing a pre-fixing agent. In this case, components or residues of the pre-fixing agent liquefy during temperature or pressure application (such as during a sintering process) and are absorbed into the through-holes due to capillary action caused by the through-holes, thereby preventing uncontrolled escape of portions or residues of the pre-fixing agent.

[0039] The substrate arrangement has a contact layer.

[0040] The contact layer is preferably a layer that enables or facilitates the formation of an integral connection between the upper side of the electronic component, particularly the optionally metallized upper side of the electronic component, and the metal foil, particularly the lower side of the metal foil.

[0041] The contact layer is disposed on the underside of the metal foil. Preferably, the contact layer is bonded to the underside of the metal foil in a planar manner.

[0042] The contact layer preferably has a thickness in the range of 5µm to 500µm, particularly preferably in the range of 5µm to 250µm, and very particularly preferably in the range of 10µm to 100µm.

[0043] The contact layer includes a contact medium. The contact medium is preferably capable of integrally bonding with the (optionally metallized) upper side of the electronic component.

[0044] The contact component preferably contains at least one component selected from the group consisting of silver and copper.

[0045] According to a preferred embodiment, the contact medium comprises at least one element selected from the group consisting of sintering materials, solder materials, and adhesives.

[0046] The sintering material is preferably selected from the group consisting of free sintering paste, sintering film and sintered preform.

[0047] According to a preferred embodiment, the sintering material comprises a sintering paste. The sintering paste is preferably a sintering paste conventionally used in the art. The sintering paste preferably comprises at least one metal selected from the group consisting of silver and copper, and an organic compound. Preferably, the metal in the sintering paste is present in particulate form. The particles can take any shape, and therefore can be present, for example, as spherical particles, flakes, or irregularly shaped silver particles. The organic compound is preferably selected from the group consisting of dispersants, binders, fatty acids, and mixtures thereof. The dispersant can be selected from dispersants conventionally used in the art. An exemplary dispersant is terpineol. The binder can be selected from polymers conventionally used in the art. Examples include cellulose derivatives, such as methylcellulose, ethylcellulose, ethylmethylcellulose, carboxycellulose, and hydroxypropylcellulose. The fatty acid can be selected from fatty acids conventionally used in the art. The fatty acids are preferably selected from the group consisting of lanolinic acid (octanoic acid), capric acid (decanoic acid), lauric acid (dorsodic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), pearlitic acid (heptadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosapentaenoic acid / eicosanoic acid), benzyl acid (dorsodic acid), and lignannic acid (tetracosanoic acid).

[0048] According to another preferred embodiment, the sintering material comprises a sintered film. Preferably, the sintered film is a sintered film conventional in the art, such as that disclosed, for example, in European patent application EP3154729 A1. Thus, the sintered film may, for example, have a sintering paste comprising metal particles (particularly silver particles) and a binder pre-dried and present on a carrier substrate. The sintered film may, for example, have a thickness in the range of 5 µm to 300 µm.

[0049] According to another preferred embodiment, the sintering material includes a sintered preform. Preferably, the sintered preform is a conventional sintered preform, such as those disclosed in European patent application EP2428293 A2.

[0050] According to a preferred embodiment, the solder material comprises at least one solder paste. The solder paste is preferably a solder paste conventionally used in the art. The solder paste preferably comprises a solder alloy and a flux. The solder alloy preferably comprises tin as a major element (the element having the largest weight proportion), particularly preferably at least one other element selected from the group consisting of copper and silver, and very particularly preferably at least one other element selected from the group consisting of bismuth, antimony, indium, germanium, cobalt, iron, and nickel. The flux is preferably a flux conventionally used in the art, particularly preferably an organic flux.

[0051] According to a preferred embodiment, the adhesive comprises a conductive adhesive. The conductive adhesive is preferably a conductive adhesive conventional in the art. The conductive adhesive preferably comprises silver particles and epoxy resin, and is preferably cured at a temperature in the range of 120°C to 200°C.

[0052] According to a particularly preferred embodiment, the contact layer comprises a pre-dried sintering paste.

[0053] According to a preferred embodiment, the substrate arrangement includes a pre-fixed layer.

[0054] The pre-fixing layer is preferably a layer bonded to the underside of the metal foil and / or the contact layer. The underside of the metal foil is preferably formed from a copper foil underside or an adhesion-promoting layer. The pre-fixing layer can be, for example, a continuous layer or an interrupted layer. The size of the continuous layer is not further limited. Therefore, the continuous layer also includes dot-like layers. With respect to the continuous layer, the pre-fixing layer can be planarly connected to the underside of the metal foil and / or the contact layer. With respect to the interrupted layer, the pre-fixing layer can include, for example, multiple portions that do not contact each other and are planarly connected to the underside of the metal foil and / or the contact layer. If the pre-fixing layer is connected to the underside of the metal foil, the contact layer is preferably at least partially planarly connected to the underside of the metal foil, and the pre-fixing layer is connected to areas of the underside of the metal foil that are not planarly connected to the contact layer. In this case, the contact layer and the pre-fixing layer are each connected to the underside of the metal foil and are preferably arranged adjacent to each other.

[0055] According to a preferred embodiment, the pre-fixing layer is formed as a continuous layer and is connected to the contact layer in a planar manner, such that at least 20%, more preferably at least 50%, particularly preferably at least 70%, very particularly preferably at least 98%, and especially 100% of the contact layer is in contact with the pre-fixing layer.

[0056] According to another preferred embodiment, the pre-fixing layer is formed in a dotted manner as a continuous layer and contacts the contact layer and / or the underside of the metal foil.

[0057] According to another preferred embodiment, the pre-fixing layer is formed as an interrupted layer comprising multiple portions that do not contact each other and are in contact with the contact layer and / or the underside of the metal foil.

[0058] The pre-fixing layer preferably comprises a pre-fixing agent. The pre-fixing agent can be used to pre-fix the substrate arrangement to the electronic component, thereby improving the transportability of the structure including the substrate arrangement and the electronic component, for example, at locations requiring further processing. Preferably, the pre-fixing agent is a temporary or releasable fixative that at least allows temporary fixation of the substrate arrangement to the electronic component. Suitable pre-fixatives are described, for example, in European patent application EP3940758 A2.

[0059] Therefore, the pre-fixing agent preferably comprises at least one compound selected from the group consisting of thermoplastic polymers, inorganic filler particles, and organic solvents. According to a preferred embodiment, the pre-fixing agent comprises at least one thermoplastic polymer and particularly preferably comprises at least one compound selected from the group consisting of inorganic filler particles and organic solvents.

[0060] Thermoplastic polymers preferably have a glass transition temperature in the range of 60°C to 120°C. The glass transition temperature is preferably determined by dynamic differential calorimetry (DDC) or differential scanning calorimetry (DSC) at a heating rate of 10°C / min. The thermoplastic polymer may, in particular, be a (meth)acrylic acid copolymer. The (meth)acrylic acid copolymer preferably has a molar mass of 35,000 g / mol to 70,000 g / mol (Mw = 35,000 g / mol to 70,000 g / mol). The molar mass is preferably determined by gel permeation chromatography (GPC). For gel permeation chromatography, the following conditions apply: polystyrene gel as the stationary phase, tetrahydrofuran as the mobile phase, and polystyrene as the standard.

[0061] The inorganic filler particles are preferably particles containing at least one element selected from the group consisting of alumina, silica, titanium dioxide, zirconium silicate, calcium silicate, mica, kaolin, and α-boron nitride. The inorganic filler particles preferably have an average particle size (d50) in the range of 5 µm to 20 µm, and particularly preferably in the range of 5 µm to 10 µm. The average particle size (d50) is preferably determined by laser diffraction.

[0062] The organic solvent preferably has a boiling point not exceeding 285°C. According to a preferred embodiment, the organic solvent is selected from the group consisting of aromatics, ketones, esters, glycol ethers, and alcohols. According to a particularly preferred embodiment, the organic solvent is selected from the group consisting of toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, polyethylene ether, ethyl acetate, isobutyl acetate, dimethyl succinate, diethylene glycol monobutyl ether, benzyl alcohol, triphenyl compounds, dimethyl compounds, and terpineols. According to a very particularly preferred embodiment, the organic solvent is selected from the group including terpineols.

[0063] According to a preferred embodiment, the substrate arrangement is adapted to connect to at least one electronic component. According to a particularly preferred embodiment, the substrate arrangement is adapted to connect a metal foil to at least one electronic component.

[0064] Electronic components are preferably understood to refer to electronic or electrical parts. Electronic components are preferably selected from the group consisting of semiconductor devices. Semiconductor devices are preferably selected from the group consisting of transistors, diodes, and integrated circuits.

[0065] According to a preferred embodiment, the electronic component includes a metal upper-side coating. The metal upper-side coating can be used to facilitate easier attachment of a metal foil to the upper side of the electronic component via a contact layer. Therefore, it is preferable that the upper side of the electronic component is formed by the metal upper-side coating. The metal upper-side coating of the electronic component preferably contains at least one element selected from the group consisting of nickel, palladium, silver, copper, and gold. According to a preferred embodiment, the electronic component includes a metal lower-side coating. The metal lower-side coating can be used to facilitate easier attachment of a base substrate to the lower side of the electronic component. Therefore, it is preferable that the lower side of the electronic component is formed by the metal lower-side coating. The metal lower-side coating of the electronic component preferably contains at least one noble metal. According to a preferred embodiment, the metal lower-side coating of the electronic component contains at least one element selected from the group consisting of gold, silver, aluminum, titanium, and nickel, and very particularly preferably silver.

[0066] Electrical contact between the upper side of the electronic component and the unfilled area of ​​the base substrate can preferably be fabricated using a substrate arrangement. For this purpose, a metal foil of the substrate arrangement is integrally bonded to the upper side of the electronic component via a contact layer. The metal foil provides a surface suitable for integral bonding with bonding leads, particularly copper bonding leads, in a particularly stable manner and with consistently high quality.

[0067] Surprisingly, it has been found that when the metal foil includes a copper layer on top of copper with an oxygen content ranging from 10 to 30 atomic percent, the top side of the substrate-arranged metal foil can bond to copper bonding leads particularly stably and with consistently high quality. Without being bound by interpretation, this effect is likely due to the oxygen content in this region preventing the uncontrolled formation of a thicker copper oxide layer, which could impair bonding performance. With an oxygen content less than 10 atomic percent, this protective layer effect is no longer sufficient. However, with an oxygen content greater than 30 atomic percent, a thick copper oxide layer may have formed, which compromises bonding performance.

[0068] The method for producing the substrate arrangement according to the invention is not further limited.

[0069] According to a preferred embodiment, a method for producing a substrate arrangement according to the present invention includes the following steps:

[0070] (A) A metal foil is provided, the metal foil comprising an upper metal foil side and a lower metal foil side, wherein the metal foil includes a copper layer having an upper copper layer side and a lower copper layer side, wherein the upper metal foil side is formed by the upper copper layer side, and wherein the upper copper layer side has an oxygen content in the range of 10 atomic percent to 30 atomic percent.

[0071] (B) Provide contact medium, and

[0072] (C) Apply a contact medium to the underside of the metal foil to form a contact layer.

[0073] In step (A) of the method, a metal foil is provided, the metal foil comprising an upper side and a lower side, wherein the metal foil comprises a copper layer having an upper side and a lower side, wherein the upper side is formed by the upper side of the copper layer, and wherein the upper side of the copper layer has an oxygen content in the range of 10 atomic percent to 30 atomic percent.

[0074] The metal foil is preferably the metal foil described elsewhere herein.

[0075] The metal foil may be, for example, commercially purchased or manufactured in a conventional manner. The copper layer on the upper side of the metal foil (e.g., commercially purchased or manufactured) may already have desired or preferred characteristics regarding oxygen and / or carbon content. Alternatively, the oxygen content may be adjusted in a manner conventional in the art.

[0076] According to one embodiment, the metal foil can be subjected to controlled heat treatment and conditioning to adjust the oxygen content on the upper side of the copper layer. For this purpose, the metal foil can be, for example, first exposed to a temperature in the range of 300°C to 600°C, particularly preferably in the range of 350°C to 550°C, and most preferably in the range of 400°C to 500°C. Exposure to this temperature is preferably for a period of 30 minutes to 10 hours, particularly preferably for a period of 1 hour to 7 hours, and most preferably for a period of 2 hours to 5 hours. The heat treatment is preferably carried out in an inert or reducing atmosphere, such as an atmosphere of process gas (95% nitrogen, 5% hydrogen). The metal foil is then preferably cooled, for example, to room temperature. After the heat treatment, conditioning is preferably performed to avoid the formation of a high proportion of copper oxide and a thick copper oxide layer. Preferably, conditioning is performed immediately after the cooling of the metal foil. For this purpose, the metal foil is preferably stored in an inert atmosphere with a low residual moisture content. The inert atmosphere can be, for example, a nitrogen atmosphere. The residual moisture content is preferably in the range of 0.2% to 1.0%, particularly preferably in the range of 0.3% to 0.7%, and most preferably in the range of 0.5% to 0.6%. Storage is preferably carried out for a period of 10 minutes to 100 hours, particularly preferably for a period of 30 minutes to 50 hours, and most preferably for a period of 10 hours to 40 hours.

[0077] According to another embodiment, the oxygen content on the upper side of the copper layer can be adjusted in an alternative manner. For example, the upper side of the copper layer can be treated with an oxidizing agent in a suitable manner. Alternatively, the surface of the upper side of the copper layer can be fully oxidized first by heat treatment in an oxidizing atmosphere or by treatment with an oxidizing agent, wherein after treatment with a reducing agent, the upper side of the copper layer is adjusted to the target value of oxygen content. In addition, plasma treatment can also be performed on the upper side of the copper layer to adjust the oxygen content.

[0078] To adjust the carbon content on the upper side of the copper layer, the upper side of the copper layer can be treated, for example, with organic compounds (e.g., citric acid or benzotriazole) that can also be used to adjust the oxygen content.

[0079] In step (B) of the method, a contact medium is provided.

[0080] The contact medium is preferably the contact medium as described elsewhere in this document.

[0081] In step (C) of the method, a contact medium is applied to the underside of the metal foil to form a contact layer.

[0082] Applying contact material to the underside of a metal foil to form a contact layer can be done by methods conventional in the art. Preferably, the contact material is applied by spraying, dispensing, spraying, brushing, dabbing, dipping, or printing, particularly screen printing or stencil printing, or by lamination.

[0083] According to a preferred embodiment, in another step (D), a pre-fixing agent is applied to the underside of the metal foil and / or the contact layer to form a pre-fixing layer, wherein the pre-fixing layer is at least partially bonded to the underside of the metal foil and / or the contact layer in a planar area. The pre-fixing agent is preferably one as described elsewhere herein. The pre-fixing agent can be applied to the underside of the metal foil and / or the contact layer by methods conventional in the art. Preferably, the pre-fixing agent is applied by spraying, dispensing, spraying, brushing, applying lightly, dipping, or printing, particularly screen printing or stencil printing.

[0084] According to a preferred embodiment, in another step (E) of the method, the contact medium, particularly preferably the sintering material, and most preferably the sintering paste are pre-dried. Pre-drying can be used to at least partially remove volatile components, such as organic compounds, contained in the contact material. Pre-drying can be carried out, for example, at a temperature in the range of 80°C to 150°C for a period of, for example, 2 to 30 minutes. Pre-drying typically results in volume shrinkage, thus reducing the thickness of the contact layer.

[0085] According to another preferred embodiment, if possible, pre-drying of the prefixant is performed in another step (F) of the method. Pre-drying can be used to at least partially remove volatile components, such as organic compounds, contained in the prefixant. Pre-drying can be carried out, for example, at a temperature in the range of 80°C to 150°C for a period of, for example, 2 to 30 minutes. Pre-drying typically causes volume shrinkage, thereby reducing the thickness of the prefixed layer. Steps (E) and (F) may also overlap.

[0086] This method produces a substrate arrangement with a metal foil, the upper side of which can be bonded to copper bonding leads in a particularly stable manner and with consistent high quality.

[0087] This invention relates to a method for producing electronic components.

[0088] The method includes the following steps:

[0089] (A) A base substrate is provided, the base substrate including an upper side, wherein the base substrate includes a metal layer.

[0090] (B) Provide an electronic component comprising an upper side and a lower side.

[0091] (C) Provides the substrate arrangement described herein.

[0092] (D) By bringing the upper side of the base substrate into contact with the lower side of the electronic component, an integrally bonded connection is formed, and

[0093] (E) The upper side of the electronic component is brought into contact with the contact layer arranged on the substrate, thereby forming an integrally bonded connection.

[0094] In step (A) of the method, a base substrate is provided. The base substrate includes a metal layer. Furthermore, the base substrate has an upper side.

[0095] For example, the metal layer of the base substrate may comprise copper or aluminum. Preferably, the metal layer of the base substrate may be formed of metal foil. According to a preferred embodiment, the metal layer of the base substrate comprises copper foil.

[0096] According to a preferred embodiment, the base substrate consists of a metal layer.

[0097] According to another preferred embodiment, the base substrate includes a metal layer and an insulating material layer. According to another preferred embodiment, the base substrate includes a metal layer and an insulating material layer integrally bonded to each other. The base substrate preferably includes an insulating material layer integrally bonded to the metal layer on a first side and a second side opposite to the first side. The insulating material of the base substrate is preferably selected from the group consisting of glass and ceramics. The ceramic may be, for example, selected from the group consisting of oxide ceramics, nitride ceramics, and carbide ceramics.

[0098] According to a preferred embodiment, the base substrate is selected from the group consisting of metal-ceramic substrates, printed circuit boards (PCBs), and lead frames. According to a particularly preferred embodiment, the base substrate is a metal-ceramic substrate conventional in the art. The metal-ceramic substrate is preferably selected from the group consisting of DCB (direct copper bonding) substrates and AMB (active metal brazing) substrates.

[0099] The upper side of the base substrate is preferably formed by a metal layer.

[0100] In step (B) of the method, an electronic component is provided. The electronic component has an upper side and a lower side.

[0101] The electronic component is preferably the electronic component as described elsewhere herein.

[0102] In step (C) of the method, a substrate arrangement is provided.

[0103] The substrate arrangement is preferably as described elsewhere in this document.

[0104] Therefore, the substrate arrangement preferably has

[0105] (a) A metal foil comprising an upper side and a lower side, wherein the metal foil includes a copper layer having an upper side and a lower side, wherein the upper side of the metal foil is formed by the upper side of the copper layer, and

[0106] (b) A contact layer disposed on the underside of the metal foil.

[0107] The upper side of the copper layer has an oxygen content ranging from 10 atomic percent to 30 atomic percent.

[0108] In step (D) of the method, the upper side of the base substrate is brought into contact with the lower side of the electronic component to form an integrally bonded connection.

[0109] For this purpose, the base substrate and electronic components are preferably positioned such that the lower side of the electronic components is preferably in contact with the upper side of the base substrate via a contact material. The contact medium can be, for example, sintering paste, solder paste, or conductive adhesive. Subsequently, the structure including the base substrate and electronic components is treated to allow for integral bonding via the contact material. Here, the lower side of the electronic components is fastened to the upper side of the base substrate. The treatment is preferably performed by introducing energy. The energy introduction can preferably be in the form of temperature application, and particularly preferably in the form of temperature and pressure application.

[0110] In step (E) of this method, the upper side of the electronic component is brought into contact with a contact layer arranged on a substrate to form an integrally bonded connection. In this case, it is preferable that the integrally bonded connection is formed between the upper side of the electronic component and a metal foil arranged on the substrate.

[0111] For this purpose, the substrate arrangement and electronic components are preferably positioned such that the contact layer of the substrate arrangement contacts the upper side of the electronic components. Subsequently, the structure including the substrate arrangement and electronic components is processed to allow for integral bonding via the contact layer. Here, the metal foil of the substrate arrangement is fastened to the upper side of the electronic components. The processing is preferably performed by introducing energy. The energy introduction can preferably be in the form of temperature application, and particularly preferably in the form of temperature and pressure application.

[0112] Steps (D) and (E) can be performed in one manufacturing step or in different manufacturing steps. In this case, steps (D) and (E) can be performed sequentially or simultaneously.

[0113] If steps (D) and (E) are performed sequentially, then step (D) may be performed before step (E). Alternatively, step (E) may also be performed before step (D).

[0114] If steps (D) and (E) are performed sequentially, according to the first embodiment, in step (D), the electronic component may be part of a first arrangement including the electronic component and a metal foil arranged on a substrate. In this case, firstly, in step (E), the first arrangement including the electronic component and the metal foil arranged on the substrate can be generated by contacting the upper side of the electronic component with the metal foil arranged on the substrate to form an integrally bonded connection between the upper side of the electronic component and the metal foil arranged on the substrate. Then, in step (D), the first arrangement can be contacted with the base substrate such that the lower side of the electronic component is integrally bonded to the upper side of the base substrate as part of the first arrangement.

[0115] If steps (D) and (E) are performed sequentially, then according to the second embodiment, in step (E), the electronic component may be part of a second arrangement including a base substrate and the electronic component. In this case, firstly, the second arrangement including the base substrate and the electronic component may be produced in step (D). Then, in step (E), the second arrangement may be brought into contact with the substrate arrangement such that the metal foil of the substrate arrangement is integrally bonded to the upper side of the electronic component as part of the second arrangement.

[0116] Electronic components are obtained by integrating a base substrate, electronic components, and metal foil through a substrate arrangement.

[0117] According to a preferred embodiment, in another step (F), a region on the upper side of the metal foil is electrically contacted with a region on the upper side of the base substrate. The electrical contact is preferably made by wire bonding. Wire bonding is preferably performed using bonding leads. The term bonding lead includes leads suitable for bonding, preferably regardless of their diameter or thickness, and particularly preferably regardless of their cross-sectional geometry (thus, for example, also as bonding strips). Bonding leads preferably contain copper. According to a preferred embodiment, the bonding leads are made of a material selected from the group consisting of copper and copper alloys. Attached Figure Description

[0118] Further features and advantages of the invention will be discovered in the following description of the accompanying drawings, in which preferred embodiments of the invention are explained with reference to schematic diagrams.

[0119] In the attached diagram:

[0120] Figure 1 A side view of the substrate arrangement according to the invention is shown; and

[0121] Figure 2 A side view of an electronic assembly obtained using a substrate arrangement according to the invention is shown.

[0122] Figure 1(Not to scale) A substrate arrangement 10 according to the present invention is shown, comprising a metal foil 20 and a contact layer 50. The metal foil 20 includes an upper metal foil side 23 and a lower metal foil side 24. The metal foil 20 is formed of a copper layer 30 and an adhesion promoting layer 40. The copper layer 30 has an upper copper layer side 33 and a lower copper layer side 34. The upper copper layer side 33 has an oxygen content in the range of 10 atomic percent to 30 atomic percent. The adhesion promoting layer 40 has an upper adhesion promoting layer side 43 and an lower adhesion promoting layer side 44. The upper adhesion promoting layer side 43 is integrally bonded to the lower copper layer side 34. The upper metal foil side 23 is formed from the upper copper layer side 33. The lower metal foil side 24 is formed from the lower adhesion promoting layer side 44. The contact layer 50 is disposed on the lower metal foil side 24 or the lower adhesion promoting layer side 44.

[0123] Figure 2 An electronic component 100, which can be manufactured by a method according to the invention, is shown. The electronic component 100 includes a metal foil 20, an electronic component 70, and a base substrate 80. The base substrate 80 has an insulating material layer 86 planarly connected to metal layers 86, 86' on both sides. The base substrate 80 is typically a metal-ceramic substrate. An upper side 83 of the base substrate 80 is formed by a metal layer 85. The electronic component 70 is disposed on the upper side 83 of the base substrate 80, having an upper side 73 and a lower side 74. The lower side 74 of the electronic component 70 is disposed on the upper side 83 of the base substrate 80. The electronic component 70 is planarly connected to the base substrate 80. For this purpose, the electronic component 70 can be fastened to the base substrate 80, for example, using a sintering paste. Therefore, a bonding region (not shown) can be located between the upper side 83 of the base substrate 80 and the lower side 74 of the electronic component 70. The electronic component 70 is connected to the metal foil 20 via the bonding region (not shown). The metal foil 20 has an upper metal foil side 23 and a lower metal foil side 24. The lower metal foil side 24 is disposed on the upper side 73 of the electronic component 40. The metal foil 20 is fastened to the electronic component 70. Fastening can be achieved by first arranging a substrate including the metal foil 20 and a contact layer (e.g., ...). Figure 1 The metal foil 20 (shown) is positioned on the upper side 73 of the electronic component 70 such that the contact layer contacts the upper side 73 of the electronic component 70. The resulting structure is then exposed to conditions that allow an integrally bonded connection to be formed between the metal foil 20 and the electronic component 70. The contact layer may, for example, consist of a pre-dried sintering paste. In this case, the structure is subjected to, for example, temperature and pressure to allow a sintered connection to be formed between the metal foil 20 and the electronic component 70. During the formation of the sintered connection, a bonding region is created between the metal foil 20 and the electronic component 70 via the contact layer (not shown). The upper side of the metal foil may contact an unfilled area (not shown) on the upper side 83 of the base substrate 80 using bonding leads. The upper side of the metal foil may also be integrally bonded to another component, particularly using a sintering material (not shown). Example

[0124] The present invention is further illustrated by the following examples; however, these examples should not be construed as limiting.

[0125] 1. Substrate arrangement production

[0126] The substrate arrangements according to the embodiments and comparative examples were produced using copper foil with a thickness of 50 µm. These copper foils were structured into 7.6 mm × 7.6 mm copper foil sheets by photolithography using a ferric chloride (FeCl3) etching solution with a suitable mask, wherein the individual copper foil sheets remained connected to each other via struts. The mask was then removed.

[0127] Example 1 :

[0128] Copper foil sheets were heat-treated in a batch oven at 450°C. To do this, after the copper foil sheets were introduced, the annealing chamber was first purged with a process gas (a mixture of 5% hydrogen and 95% nitrogen). This process gas treatment was carried out at a gas flow rate of 16 L / min for a duration of 30 minutes (residual oxygen content ≤0.2%). The oven was then heated at a heating rate of 1°C / min until the temperature of 450°C was reached. After 3 hours of treatment, the oven was shut off and allowed to cool. Once room temperature was reached, the gas flow was stopped, and the copper foil sheets were removed.

[0129] These copper foil sheets are then subjected to conditioning steps. For this purpose, the copper foil sheets are stored in a nitrogen atmosphere with a residual moisture content of 0.5% to 0.6% in a drying oven at 25°C for a period of 24 hours.

[0130] The copper foil sheet was then applied to a transfer foil (chip-cut foil) within a plastic frame and metallized using a 400 nm thick electroplated contact layer. A silver sintering layer was then applied to this contact layer. For this purpose, a sintering paste (ASP043-60, Heraeus) was applied to a 7.1 mm × 7.1 mm area (wet layer thickness = 40 µm) using stencil printing. As an adjunct to the area covered with the sintering paste, the coating had a 0.25 mm wide peripheral edge region free of sintering paste. The copper foil sheet with the sintering paste on the coating was then dried in air at 110 °C for ten minutes, removed from the frame, separated from the transfer film, and laser-separated by separation struts, resulting in a substrate arrangement with a metal foil comprising an upper metal foil side, a lower metal foil side, and a contact layer disposed on the lower metal foil side.

[0131] Example 2 :

[0132] Example 2 was performed similarly to Example 1, except that during the conditioning step, the copper foil was stored in a drying oven at 25°C in a nitrogen atmosphere with a residual moisture content of 0.5% to 0.6% for 20 hours. The copper foil was then directly further processed.

[0133] Example 3 :

[0134] Example 3 was performed similarly to Example 1, except that during the conditioning step, the copper foil was stored in a drying oven at 25°C under a nitrogen atmosphere with a residual moisture content of 0.5% to 0.6% for 15 hours. The copper foil was then directly further processed.

[0135] Example 4 :

[0136] Example 4 was performed similarly to Example 1, except that during the conditioning step, the copper foil was stored in a drying oven at 25°C in a nitrogen atmosphere with a residual moisture content of 0.5% to 0.6% for 10 hours. The copper foil was then directly further processed.

[0137] Example 5 :

[0138] Example 5 was performed similarly to Example 1, except that during the conditioning step, the copper foil was stored in a drying oven at 25°C under a nitrogen atmosphere with a residual moisture content of 0.5% to 0.6% for 30 minutes. The copper foil was then directly further processed.

[0139] Comparative Example 1 :

[0140] Comparative Example 1 was performed similarly to Example 1, however, without the adjustment steps. The copper foil was directly further processed.

[0141] Comparative Example 2 :

[0142] Comparative Example 2 was carried out similarly to Example 1, except that no conditioning steps were performed, and the foil was stored at room temperature (24°C) in a standard atmosphere (air) for 96 hours before further processing.

[0143] 2. Production of electronic components

[0144] To manufacture electronic components, the first step is to create an arrangement of various base substrates and electronic parts. Commercially available direct metallized copper-ceramic substrates (DCB; Condura) are used. ® The classic model (Herabilis) and a silicon chip with a size of 8.8mm × 8.8mm (thickness = 70µm) with metallization (NiP / Pd) on the bottom and top sides as the base substrate.

[0145] Sintering paste (ASP 338-28, Heraeus) was applied to the upper side of a copper-ceramic substrate using a stencil printing method (wet layer thickness = 100µm). The copper-ceramic substrate with the sintering paste was dried in air at 100°C for ten minutes and then cooled. A silicon chip was positioned on the pre-dried sintering paste such that the lower side of the silicon chip was in contact with the upper side of the corresponding copper-ceramic substrate.

[0146] Subsequently, the corresponding substrate arrangements according to Examples 1 to 5 and Comparative Examples 1 and 2 are positioned on each upper side of the silicon chip such that the silver sintered layer of the corresponding substrate arrangement is in contact with the upper side of the silicon chip.

[0147] The resulting structure was then sintered. Sintering was performed in a sintering press (Pink, Wertheim) at a pressure of 20 MPa and a temperature of 250°C for a duration of three minutes in a nitrogen atmosphere. This produced electronic components, each equipped with a metal foil arranged from the substrates of Examples 1 to 5, or equipped with a metal foil arranged from the substrates of Comparative Examples 1 and 2.

[0148] Subsequently, copper bonding leads (Power Cu Soft, Heraeus) with a diameter of 400 μm are bonded to the upper side of the metal foil of the manufactured electronic component. For this purpose, the copper bonding leads are bonded to the upper side of the metal foil of the electronic component using a wedge-to-wedge bonding method at a frequency of 80 kHz, employing an Asterion Orthodyne Bonder (Kulicke & Sofna).

[0149] 3. Evaluation

[0150] 3.1 Determine the oxygen and carbon content on the upper side of the copper layer in the substrate arrangement (under conditions of no sputtering and sputtering). Down)

[0151] The oxygen and carbon content in the upper copper layer of the metal foil of electronic components produced using the substrates arranged in Examples 1 to 5 and Comparative Examples 1 and 2 were determined by Auger electron spectroscopy.

[0152] Measurements were performed using a PHI 5800 MultiTechnique ESCA system (Physical Electronics, Inc., USA). After rinsing twice with 4N nitrogen, the substrate to be measured was introduced into the measurement chamber of the PHI 5800 MultiTechnique ESCA system. In the measurement chamber, the copper and oxygen content on the top side of the copper layer was measured using Auger electron spectroscopy (AE). The PHI 5800 MultiTechnique ESCA system was also used for depth distribution measurements. For this purpose, the top side of the copper layer of the sample was sputtered for 180 s and 300 s, and the copper and oxygen content on the top side of the copper layer was measured using AE. Sputtering was performed using an ion gun (with xenon ions as the ion source) operating at a sputtering rate of 1.0 nm / min relative to a reference tantalum pentoxide at an accelerating voltage of 4 kV. The analytical parameters for Auger electron spectroscopy were 5 kV, beam current of 15 nA, and a measurement spot size of 100 μm × 100 μm. The signal obtained by Auger electron spectroscopy was estimated using software (PHI MultiPak Version 9.9 (Physical Electronics, Inc., USA)). Measurements were performed in five different regions of the substrate arrangement. The corresponding average values ​​of the five measurements are given in Table 1.

[0153] 3.2 Evaluation of Results

[0154] Next, the metal foil of the electronic components produced using the substrate arrangements of Examples 1 to 5 and Comparative Examples 1 and 2 was examined to determine whether the upper side of the metal foil could be bonded to the copper bonding leads in a particularly stable manner and with consistent high quality. For this purpose, according to DVS Manual 2811 (German Welding Association), the electronic components produced using the substrate arrangements of Examples 1 to 5 and Comparative Examples 1 and 2 and equipped with bonding leads were subjected to a mechanical tensile test. The tensile test examined the connection between the bonding leads and the metal foil surface of the electronic components. The tensile test was performed using an XYTEC Condor Sigma tensile testing machine (xyztec bv) equipped with a force sensor (10 kg) and a pull hook (1200 μm). The bonding results were evaluated according to DVS Manual 2811 (German Welding Association) as follows:

[0155] "--": This indicates that the bond does not adhere to the copper surface (so-called "wedge peeling").

[0156] "-": Lead breakage occurs in the transition area from the bonded area to the lead wire region under significantly reduced tensile force (<10N) (so-called "heel breakage").

[0157] "+": Lead breakage (so-called heel breakage) occurs in the transition area from the bonded area to the lead wire region under slightly reduced tension (10N to 15N).

[0158] "++": Lead wire breaks under high tensile force (>20N).

[0159] The results are shown in Table 1.

[0160]

[0161] Table 1: Results of inspection of substrate arrangement in Examples 1 to 5 and Comparative Examples 1 to 2 .

[0162] 3.3 Assessment

[0163] The results show that, using the substrate arrangements of Examples 1 to 5 according to the present invention, a particularly stable bond can be achieved between the copper bonding leads and the upper side of the metal foil arranged on the substrate. This bond is more stable and has the same quality than the bonds obtained using the substrate arrangements of Comparative Examples 1 and 2. In particular, the upper side of the metal foil has a uniform composition, which enables the formation of a stable bond with the same high quality.

[0164] List of icon numbers :

[0165] 10 Substrate Arrangement

[0166] 20 metal foil

[0167] 23 metal foil upper side

[0168] 24 Metal Foil Underside

[0169] 30 copper layers

[0170] 33 Copper Layer Top Side

[0171] 34 Copper layer underside

[0172] 40 Adhesion-promoting layer

[0173] 43 Adhesion promoting layer upper side

[0174] 44 Adhesion promoting layer underside

[0175] 50 contact layers

[0176] 70 electronic components

[0177] 73 Upper side (electronic components)

[0178] 74 Lower side (electronic components)

[0179] 80 base substrate

[0180] 83 Top side (base substrate)

[0181] 85, 85' metal layer

[0182] 86 layers of insulating material

[0183] 100 electronic components

Claims

1. A substrate arrangement, said substrate arrangement comprising (a) A metal foil comprising an upper side and a lower side, wherein the metal foil comprises a copper layer having an upper side and a lower side, wherein the upper side of the metal foil is formed by the upper side of the copper layer, and (b) A contact layer disposed on the underside of the metal foil. characterized in that The upper side of the copper layer has an oxygen content in the range of 10 atomic percent to 30 atomic percent.

2. The substrate arrangement of claim 1, wherein, The upper side of the copper layer has a carbon content in the range of 30 atomic percent to 60 atomic percent.

3. A substrate arrangement according to claim 1 or 2, characterized in that The upper side of the copper layer is designed to allow for depth distribution measurements after a sputtering time of 300 s (sputtering rate: 1.0 nm / min for reference tantalum pentoxide). Ion source: xenon ions, accelerating voltage: 4kV), the exposed copper layer has an oxygen content of less than 1.0 atomic percentage.

4. The substrate arrangement according to any one of the preceding claims, characterized in that, The metal foil includes an adhesion promoting layer having an upper adhesion promoting layer and a lower adhesion promoting layer, wherein the upper adhesion promoting layer is integrally bonded to the lower copper layer.

5. The substrate arrangement according to claim 4, characterized in that, The adhesion-promoting layer is multi-layered.

6. The substrate arrangement according to any one of the preceding claims, characterized in that, The contact layer includes a contact medium.

7. The substrate arrangement according to claim 6, characterized in that, The contact medium includes at least one component selected from the group consisting of silver and copper.

8. The substrate arrangement according to claim 6 or 7, characterized in that, The contact medium comprises sintered material.

9. The substrate arrangement according to claim 8, characterized in that, The contact layer contains a pre-dried sintering paste.

10. A method for producing electronic components, the method comprising the following steps (A) A base substrate is provided, the base substrate including a top side, wherein the base substrate includes a metal layer. (B) Provide electronic components, said electronic components including an upper side and a lower side, and (C) Providing a substrate arrangement according to any one of the preceding claims (D) The upper side of the base substrate is brought into contact with the lower side of the electronic component to form an integrally bonded connection, and (E) The upper side of the electronic component is brought into contact with the contact layer disposed on the substrate, thereby forming an integrally bonded connection.

11. An electronic component capable of being manufactured by the method of claim 10.

Images