Micromechanical component, and method for its manufacture

Abstract

Micromechanical component (11; 12; 13), in particular a capacitive and / or piezoresistive pressure sensor (11; 12; 13), comprising a sensor element (2), wherein the sensor element (2) has a contact surface (3), wherein a bond wire (4) contacts the sensor element (2) at the contact surface (3), wherein the sensor element (2), the contact surface (3) and / or the bond wire (4) are completely or at least partially surrounded by a gel (5), wherein the gel is a perfluorinated or partially fluorinated corrosion protection gel, wherein a corrosion protection coating is used, comprising a compound of general formula (I): R a -(R b ) n -X1 and / or the general formula (II): X1-(R b ) n -R a -(R b ) m -X2 includes, whereby R afor a perfluorinated polyether or a perfluorinated alkyl group with 1 to 16 carbon atoms, in particular with 6 to 12 carbon atoms, stands, R b for an alkyl spacer with 1 to 5 carbon atoms, in particular a methylene or ethylene spacer, stands, X1 and X2 each independently represent an amino, thiol, isocyanate, isothiocyanate, carboxamide, or polyether alcohol group, and n, m are each independently 0 or 1, where at least n or m is equal to 1.

Description

[0001] The present invention relates to a micromechanical component comprising a perfluorinated or partially fluorinated corrosion protection gel according to claim 1, for example pressure, flow and / or temperature sensors, in particular capacitive and / or piezoresistive pressure sensors, and a method for manufacturing the micromechanical component according to claim 9. State of the art

[0002] Corrosion-related measurement errors occur in electronic and micromechanical components, especially capacitive and / or piezoresistive pressure sensors. Aluminum components, such as the bond wire and bond pads (bond wire contact surfaces) of piezoresistive pressure sensor elements, are particularly susceptible to this.

[0003] Therefore, electronic and micromechanical components, especially those used in automotive engineering where they are exposed to highly corrosive agents (NOx), must be protected against corrosion. x are exposed to, and protected.

[0004] Traditionally, piezoresistive pressure sensor elements, along with their associated contact surfaces and bonding wires, are embedded in a gel designed to prevent direct contact with corrosive agents without impairing the sensor's function. To achieve this, the corrosion protection gels should be diffusion-tight. However, achieving absolute diffusion tightness for both gases and liquids is difficult.

[0005] Furthermore, the material costs of the gels traditionally used as corrosion protection gels are high, which is why increasing the protective function by increasing the thickness of the gel layer is not practical.

[0006] To neutralize penetrating acids before they come into contact with sensitive components, some corrosion protection gels contain an acid binder, such as lime. However, since lime does not prevent the diffusion of substances like carbon dioxide and water, some corrosion-related measurement errors cannot be ruled out despite the addition of lime.

[0007] From US patent 2005 / 0037135 A1, a coating process and coatings for MEMS devices are known, which generally comprise a two-stage process of coating a substrate surface with a first silane, followed by a second treatment with or without a second silane and elevated temperatures.

[0008] From US patent 2004 / 0037956 A1, a method for coating a microelectromechanical system (MEMS) with a silane adhesion promoter is known by: a) mixing the silane adhesion promoter with a low-volatility matrix material in a coating material container; b) placing the MEMS in a vacuum coating chamber connected to the coating material container; c) evacuating the vacuum coating chamber to a predetermined pressure; and maintaining the pressure in the vacuum coating chamber for a specific time to chemically deposit the silane adhesion promoter onto the surface of the MEMS.

[0009] Release films are known from EP 0433070 A2, in particular those suitable for use with highly aggressive pressure-sensitive adhesives.

[0010] US 6071564 A discloses the use for protective coatings of compositions containing 10 to 60% of a (per)fluoropolyether prepolymer with polyisocyanate functionality.

[0011] From EP 2799755 A2, coating systems are known that offer corrosion resistance and optional lubrication for threaded connections.

[0012] From DE 60207398 T2, an anti-growth composition is known, comprising a hardened or cross-linked polymer free of perfluoropolyether structural units and a liquid polymer or oligomer containing fluorinated alkyl or alkoxy, and a method for anti-growth inhibition in an aquatic environment.

[0013] From US patent 2005 / 0187134 A1, a method for treating surfaces to protect or clean them is known.

[0014] Optical elements with fluorochemical surface treatments are known from US patent 2002 / 0090515 A1. The invention further relates to materials such as retroreflective films, road markings, and projection screens, comprising a binder and the surface-treated optical elements.

[0015] From EP 1905800 A1, a copolymer of a perfluoropolyether derivative and a photosensitive polymer, a composition for forming banks containing the copolymer, and a method for forming banks using the composition are known.

[0016] From CN 101326207 A, a carbon nanotube-containing composition is known, comprising a carbon nanotube and a urethane compound obtained by a reaction between a hydroxyl-containing (meth)acrylate and an isocyanate compound. Also disclosed is a composite body provided on at least one surface of a support with a coating film or cured film of such a carbon nanotube-containing composition. Disclosure of the invention Advantages of the invention

[0017] The perfluorinated or partially fluorinated corrosion protection gel and the corrosion protection coating according to the invention, for electronic and / or micromechanical components, for example pressure, flow and / or temperature sensors, in particular capacitive and / or piezoresistive pressure sensors, according to claim 1 and claim 9 respectively, have the advantage that the compounds used according to the invention are of the general formula (I): R a -(R b ) n -X1 and / or the general formula (II): X1-(R b ) n -R a -(R b ) m -X2, where R a stands for a perfluorinated polyether or a perfluorinated alkyl group with 1 to 16 carbon atoms, in particular with 6 to 12 carbon atoms; R bwhere X1 represents an alkyl spacer with 1 to 5 carbon atoms, in particular a methylene or ethylene spacer; X1 and X2 each independently represent an amino, thiol, isocyanate, isothiocyanate, carboxamide, or polyether alcohol group; and n and m are each independently 0 or 1, the components are oriented on the surface to be protected such that their polar regions contact the surface to be protected, while their nonpolar regions extend away from the surface to be protected. This creates a nonpolar environment around the surface to be protected, which prevents polar, corrosive agents from penetrating to the surface to be protected.

[0018] An additional benefit can be achieved by the fact that the compounds used according to the invention have adhesion-promoting properties and therefore not only passivate the surface to be protected, but also improve the adhesion of the gel.

[0019] Due to these advantageous properties, the corrosion protection gel and the corrosion protection coating according to the invention extend the service life of electronic and / or micromechanical components and expand their application possibilities in corrosive environments.

[0020] In particular, the compounds used according to the invention serve to protect metallic components of electronic and / or micromechanical components from corrosion, for example, components comprising aluminum, gold, and / or copper. Advantageously, a corrosion protection coating according to the invention can protect the bond wire and the bond wire contact of capacitive and / or piezoresistive pressure sensors from corrosion.

[0021] Within the scope of the present invention, the term "amino group" includes primary, secondary, and tertiary amino groups. Likewise, the term "carboxamide group" according to the invention includes both carboxamide groups with a primary amide and carboxamide groups with a secondary or tertiary amide.

[0022] Within the scope of the present invention, X1 and X2 of the compounds of general formula (I) and / or (II) preferably each independently represent -NH2, -CONH2 or -CH2(OCH2CH2) r OH with r = 1 to 5.

[0023] In a preferred embodiment of the present invention, R a in the compounds of the general formula (I) and / or (II) according to the invention for a perfluorinated polyether of the general formula (III): -CF2-(O-CF2-CF2) p -(O-CF2) q -O-CF2- where the ratio p to q is in a range of ≥ 0.5 to ≤ 40, for example from ≥ 10 to ≤ 31.

[0024] Preferably, the compounds of general formula (I) or (II) within the scope of the present invention have an average molecular mass of ≥ 250 AMU to ≤ 4000 AMU, in particular of ≥ 300 AMU to ≤ 3600 AMU. Compounds of general formula (I) or (II) with a molecular mass in this range have proven advantageous, particularly in connection with corrosion protection gels, since such compounds exhibit low volatility due to their size and are simultaneously small enough to diffuse through the gel.

[0025] For example, the compound of general formula (I) within the scope of the present invention can be a perfluoropolyethercarboxamide or a 1,1,2,2-tetrahydroperfluoroalkyltrialkoxysilane, for example a 1,1,2,2-tetrahydroperfluorohexyltrialkoxysilane, a 1,1,2,2-tetrahydroperfluorooctyltrialkoxysilane, a 1,1,2,2-tetrahydroperfluorodecyltrialkoxysilane or a 1,1,2,2-tetrahydroperfluorododecyltrialkoxysilane, in particular 1,1,2,2-tetrahydroperfluorohexyltrimethoxysilane, 1,1,2,2-tetrahydroperfluorohexyltriethoxysilane, 1,1,2,2-tetrahydroperfluorohexyltriethoxysilane, 1,1,2,2-Tetrahydroperfluorooctyltriethoxysilane, 1,1,2,2-Tetrahydroperfluorodecyltrimethoxysilane, 1,1,2,2-Tetrahydroperfluorodecyltriethoxysilane, 1,1,2,2-Tetrahydroperfluorododecyltrimethoxysilane or 1,1,2,2-Tetrahydroperfluorododecyltriethoxysilane, or a perfluorocarboxylic acid, for example perfluorohexanoic acid, perfluorooctanoic acid, perfluorodecanoic acid or perfluorodecanoic acid,especially perfluorooctanoic acid or perfluorodecanoic acid.

[0026] A compound of general formula (II) can, for example, be an alpha-omega-perfluoropolyetherdiol or an alpha-omega-perfluoropolyether-bis-trialkoxysilane, for example an alpha-omega-perfluoropolyether-bis-trimethoxysilane or an alpha-omega-perfluoropolyether-bis-triethoxysilane.

[0027] Within the scope of the present invention, the following products of the Solvay company, which fall under the general formula (I) or (II), have proven to be suitable according to the invention: - Fluorolink® D10 (alpha-omega-per¬fluoro¬poly¬etherdiol (HO-CH2-CF2-(O-CF2-CF2) p -(O-CF2) q -O-CF2-CH2-OH with p / q = 0.5-3.0), average molecular mass: 1000-1500 AMU, CAS No.: 88645-29-8); - Fluorolink® S10 (alpha-omega-perfluoropolyether-bis-triethoxysilane, average molecular mass 1400-1800 AMU, CAS No.: 223557-70-8); - DA 306 (Perfluoropolyethercarboxamide (PFPE-CO-NH2), average molecular mass: 3000 AMU, CAS No.: 370097-12-4): - Fluorolink® C (Perfluoropolyethercarboxylic acid (PFPE-COOH), average molecular mass: 1000 AMU); - Fluorolink® D10 / D10-H (perfluoropolyether alcohol derivative (PFPE-CH2OH), average molecular mass: 500 - 1000 AMU); - Fluorolink® E10 / E10-H (perfluoropolyether alcohol derivative (PFPE-CH2(OCH2CH2) r OH with r = 1 to 5), average molecular mass: 500 - 1000 AMU); - Fluorolink® F10 (Perfluoropolyether phosphate (PFPE phosphate), average molecular mass: 2400 - 3100 AMU); - DA 305 (perfluoropolyether derivative, average molecular mass: 3500 AMU); - DA 308 (perfluoropolyether derivative, average molecular mass: 300 AMU)

[0028] For the purposes of the present invention, a gel is understood to be a gel suitable for “electronic packaging”, i.e. for the hermetic and quasi-hermetic encapsulation of electronic components.

[0029] Preferably, a perfluorinated or partially fluorinated corrosion protection gel according to the invention is a gel based on perfluoropolyethers or a gel based on polydialkylsiloxane, wherein alkyl groups have been partially replaced by perfluorinated alkyl groups, for example polydimethylsiloxane, wherein CH3 groups have been partially replaced by CF3 groups, or a mixture thereof.

[0030] It is more advantageous to homogeneously mix the compounds of general formula (I) and / or (II) into the perfluorinated or partially fluorinated corrosion protection gel. The proportion of compounds of general formula (I) and (II) can be ≥ 0.01 wt.% to ≤ 30 wt.%, for example ≥ 0.1 wt.% to ≤ 15 wt.%, and in particular ≥ 0.5 wt.% to ≤ 5 wt.%, based on the total weight of the gel.

[0031] Preferably, the corrosion protection gel according to the invention further comprises acid-neutralizing and / or base-neutralizing compounds, for example alkali and / or alkaline earth carbonates, hydrogen carbonates, carboxylates, oxides, hydroxides, phosphates, hydrogen phosphates, and / or borates, borax, aluminum oxide and / or hydrated aluminum oxide, in particular calcium carbonate. The proportion of acid-neutralizing and base-neutralizing compounds can be ≥ 0.01 wt.% to ≤ 40 wt.%, based on the total weight of the gel.

[0032] Another object of the present invention relates to a method for producing a corrosion protection coating according to the invention for electronic and / or micromechanical components, for example pressure, flow and / or temperature sensors, in particular capacitive and / or piezoresistive pressure sensors, in which a compound of the general formula (I): R a -(R b ) n -X1 and / or the general formula (II): X1-(R3) n -R a -(R b ) m -X2, where R a for a perfluorinated polyether or a perfluorinated alkyl group with 1 to 16 carbon atoms, in particular with 6 to 12 carbon atoms, stands, R b for an alkyl spacer with 1 to 5 carbon atoms, in particular a methylene or ethylene spacer, stands, X1, X2 each independently for an amino, thiol, isocyanate, isothiocyanate, carboxamide or polyether alcohol group stand, and n, m are each independently 0 or 1, - is evaporated and applied to the electronic and / or micromechanical component by vapor deposition, or - dissolved / dispersed in water, an alcohol, for example 2-propanol, or a hydrocarbon, and the electronic and / or micromechanical component to be coated is immersed in the solution / dispersion and / or sprayed with the solution / dispersion.

[0033] Preferably, the electronic and / or micromechanical component to be coated is treated with oxygen plasma, water vapor plasma and / or UV light, for example with a wavelength of ≤ 400 nm, prior to coating. Advantageously, such pretreatment can improve the adhesion of the coating and thus its corrosion-protective effect.

[0034] Insofar as the compound of general formula (I) and / or (II) is dissolved / dispersed in water, an alcohol, or a hydrocarbon, the proportion of compounds of general formula (I) and (II) within the scope of the present invention can be ≥ 0.05 wt.% to ≤ 10 wt.%, based on the total weight of the solution / dispersion.

[0035] A further object of the present invention relates to an electronic and / or micromechanical component, for example a pressure, flow and / or temperature sensor, in particular a capacitive and / or piezoresistive pressure sensor, comprising a sensor element, for example a pressure, flow and / or temperature sensor element, in particular a capacitive and / or piezoresistive pressure sensor element, wherein the sensor element has a contact surface, wherein a bond wire contacts the sensor element at the contact surface, wherein the sensor element, the contact surface and / or the bond wire are completely or at least partially surrounded by a gel, characterized in that - the gel is a corrosion protection gel according to the invention, and / or - the surface of the sensor element, the contact surface and / or the bond wire is completely or at least partially coated with a corrosion protection coating according to the invention. Drawings

[0036] Further advantages and advantageous embodiments of the invention are illustrated by the drawings and explained in the following description. It should be noted that the figures are for descriptive purposes only and are not intended to limit the invention in any way. They show Fig. 1 a schematic cross-section through a first embodiment of a pressure sensor according to the invention with a corrosion protection gel according to the invention; Fig. 2 a schematic cross-section through a second embodiment of a pressure sensor according to the invention with a corrosion protection coating according to the invention; Fig. 3 a schematic cross-section through a third embodiment of a pressure sensor according to the invention with a corrosion protection gel and a corrosion protection coating according to the invention; and Fig. 4 the results of electrochemical short-term corrosion measurements on two aluminium plates coated according to the invention and one uncoated aluminium plate.

[0037] Fig. Figure 1 shows a first embodiment of a pressure sensor 11 according to the invention. Fig. As shown in Figure 1, the pressure sensor 1 comprises a capacitive and / or piezoresistive pressure sensor element 2. This sensor element 2 has a contact surface (the so-called "bond pad") 3, via which a bond wire 4 contacts the sensor element 2. The sensor element 2 may comprise silicon. The bond wire 4 and the contact surface 3 may comprise or be formed from aluminum, gold, and / or copper.

[0038] In this embodiment, the sensor element 2 is arranged, and in particular attached, to a substrate 8, for example by means of an adhesive layer 7. Furthermore, the pressure sensor has a gel ring 9, which is also arranged, and in particular attached, to the substrate 8. The gel ring 9 is positioned on the substrate 8 such that it encloses the assembly consisting of the sensor element 2, the contact surface 3, and the bonding wire 4. The substrate 8 and the gel ring 9 can, for example, be made of a ceramic material or a polymer, such as polybutylene terephthalate (PBT).

[0039] How Fig. Figure 1 shows that the trough formed by the gel ring 9 and the substrate 8 is filled with a corrosion protection gel 5 according to the invention in such a way that the sensor element 2, the contact surface 3 and the bond wire 4 are completely surrounded by the gel 5 and are thereby protected from corrosive agents.

[0040] Fig. Figure 2 shows a second embodiment of a pressure sensor 12 according to the invention, which differs from the first in Fig. The embodiment shown in Figure 1 differs in that it has a corrosion protection coating 6 according to the invention which completely covers the surface of the sensor element 2 and the contact surface 3 and partially covers the surface of the bond wire 4, using a conventional corrosion protection gel 5'.

[0041] Fig. Figure 3 shows a third embodiment of a pressure sensor 13 according to the invention, which differs from the first and second embodiments in Fig. The embodiment of a pressure sensor according to the invention shown in Figures 1 and 2 differs in that the pressure sensor 1 has both a corrosion protection gel 5 and a corrosion protection coating 6 according to the invention.

[0042] Fig.Figure 4 shows the results of electrochemical short-term corrosion measurements in salt water solution (tablet measurements) on two aluminum plates 14, 15 coated with a corrosion protection layer according to the invention and one uncoated aluminum plate 16. Before the measurement, the aluminum plate used for measurement 14 was coated according to the invention with 1,1,2,2-tetrahydroperfluorooctyltrimethoxysilane (PFOTMS) and the aluminum plate used for measurement 15 was coated according to the invention with alpha-omega-perfluoropolyether bis-triethoxysilane (Fluorolink® S10). The results of the electrochemical short-term corrosion measurement clearly show that the aluminium plates coated according to the invention with 1,1,2,2-tetrahydro-perfluorooctyltrimethoxysilane (PFOTMS) 14 and ha-omega-perfluoropolyether-bis-triethoxysilane (Fluorolink® S10) 15 exhibit a significantly lower corrosion current in salt water solution than the untreated aluminium plate 16.

Claims

[1] Micromechanical component (11; 12; 13), in particular a capacitive and / or piezoresistive pressure sensor (11; 12; 13), comprising a sensor element (2), wherein the sensor element (2) has a contact surface (3), wherein a bond wire (4) contacts the sensor element (2) at the contact surface (3), wherein the sensor element (2), the contact surface (3) and / or the bond wire (4) are completely or at least partially surrounded by a gel (5), wherein the gel is a perfluorinated or partially fluorinated corrosion protection gel, wherein a corrosion protection coating is used, comprising a compound of general formula (I): R a -(R b ) n -X1 and / or the general formula (II): X1-(R b ) n -R a -(R b ) m -X2 includes, whereby R afor a perfluorinated polyether or a perfluorinated alkyl group with 1 to 16 carbon atoms, in particular with 6 to 12 carbon atoms, stands, R b for an alkyl spacer with 1 to 5 carbon atoms, in particular a methylene or ethylene spacer, stands, X1 and X2 each independently represent an amino, thiol, isocyanate, isothiocyanate, carboxamide, or polyether alcohol group, and n, m are each independently 0 or 1, where at least n or m is equal to 1. [2] Micromechanical component according to claim 1, characterized by , that X1, X2 each independently for -NH2, -CONH2 or -CH2(OCH2CH2) r OH with r = 1 to 5. [3] Micromechanical component according to claim 1 or 2, characterized by , that R a for a perfluorinated polyether of general formula (III): -CF2-(O-CF2-CF2) p -(O-CF2) q -O-CF2- where the ratio p to q is in a range of ≥ 0.5 to ≤ 40, for example from ≥ 10 to ≤ 31. [4] Micromechanical component according to any of the preceding claims, characterized by , that the compound of general formula (I) or (II) has an average molecular mass of ≥ 250 AMU to ≤ 4000 AMU, in particular of ≥ 300 AMU to ≤ 3600 AMU. [5] Micromechanical component according to any of the preceding claims, characterized by , that the compound of general formula (I) is a perfluoropolyethercarboxamide or a perfluorocarboxylic acid, for example perfluorohexanoic acid, perfluorooctanoic acid, perfluorodecanoic acid or perfluorodecanoic acid, in particular perfluorooctanoic acid or perfluorodecanoic acid. [6] Micromechanical component according to any of the preceding claims, characterized by, that the proportion of compounds of the general formula (I) and (II) is ≥ 0.01 wt.% to ≤ 30 wt.%, for example ≥ 0.1 wt.% to ≤ 15 wt.%, in particular ≥ 0.5 wt.% to ≤ 5 wt.%, based on the total weight of the gel. [7] Micromechanical component according to any of the preceding claims, characterized by that the gel further comprises acid-binding and / or base-binding compounds, for example alkali and / or alkaline earth carbonates, hydrogen carbonates, carboxylates, oxides, hydroxides, phosphates, hydrogen phosphates, borates, borax, aluminium oxide, hydrated aluminium oxide, in particular calcium carbonate. [8] Micromechanical component according to any of the preceding claims, characterized by , that the proportion of acid-binding and base-binding compounds is ≥ 0.01 wt.% to ≤ 40 wt.%, based on the total weight of the gel. [9] Method for manufacturing a micromechanical component according to one of the preceding claims, comprising a compound of the general formula (I): R a -(R b ) n -X1 and / or the general formula (II): X1-(R b ) n -R a -(R b ) m -X2, where - R a for a perfluorinated polyether or a perfluorinated alkyl group with 1 to 16 carbon atoms, in particular with 6 to 12 carbon atoms, stands, - R b for an alkyl spacer with 1 to 5 carbon atoms, in particular a methylene or ethylene spacer, stands, - X1, X2 each independently represent an amino, thiol, isocyanate, isothiocyanate, carboxamide or polyether alcohol group, and - n, m are each independently 0 or 1, where at least n or m is equal to 1 evaporated and applied to the micromechanical component by gas phase deposition, or dissolved / dispersed in water, an alcohol, for example 2-propanol, or a hydrocarbon, and the micromechanical component to be coated is immersed in the solution / dispersion and / or sprayed with the solution / dispersion. [10] Method according to claim 9, characterized by that the electronic and / or micromechanical component to be coated is treated with oxygen plasma, water vapor plasma and / or UV light, for example with a wavelength of ≤ 400 nm, before coating. [11] Method according to claim 9 or 10, characterized by , that the proportion of compounds of the general formula (I) and (II) is ≥ 0.05 wt.% to ≤ 10 wt.%, based on the total weight of the solution / dispersion.

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