Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/80—Constructional details
  • H10N30/88—Mounts; Supports; Enclosures; Casings
  • H10N30/883—Additional insulation means preventing electrical, physical or chemical damage, e.g. protective coatings
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/80—Constructional details
  • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
  • H10N30/872—Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices

Definitions

• the present invention relates first of all to a passivation material for an electrical component according to the preamble of patent claim 1 and to a piezoelectric component in a multilayer construction according to the preamble of patent claim 11.
• Piezoelectric components can be designed, for example, in the form of piezo actuators as multilayer components with a number of alternately arranged piezoelectric ceramic layers and electrode layers and are becoming increasingly important in modern electrical engineering.
• piezo actuators are used as actuators in connection with valves and the like.
• a known piezo actuator is described in detail in DE 196 46 676 Cl, for example.
• the effect is exploited that they charge up under a mechanical pressure or tension and, on the other hand, expand along the main axis of the ceramic layer when an electrical voltage is applied.
• monolithic multilayer actuators are used, which consist of a sintered stack of thin foils made of piezoceramic (for example lead zirconate titanate) with embedded metal electrode layers. The electrode layers are mutually led out of the stack and electrically connected in parallel via external metallizations.
• a strip or band-shaped, continuous outer metallization is applied to the two contact sides of the stack, which is connected to all electrode layers of the same polarity.
• a contact made in many forms for example a copper-clad Kapton film strip or the like, is often applied. If an electrical voltage is applied to the external contact, the piezo foils expand in the direction of the field. Due to the mechanical series connection of the individual piezo foils, the nominal expansion of the entire stack is achieved even at relatively low electrical voltages.
• the electrode layers In order to achieve an optimal deflection of the piezoceramic multilayer actuator with a minimal space requirement at the same time, the electrode layers must cover the entire cross section of the actuator, except for an inactive one
• Contact zone include. This means that electrode layers of alternating polarity are exposed on the side surfaces of the multilayer ceramic.
• Passivation is generally a type of protective layer, insulation layer or the like, by means of which electrical flashovers and short circuits between adjacent electrode layers can be avoided. Without passivation, such flashovers and short circuits could be caused, for example, by mechanical damage to the surface or by contamination with impurities (e.g. grinding dust, fingerprints and the like), moisture (e.g. Ag migration or the like) or operating materials (e.g. diesel, rapeseed methyl ester and the like) become. Such damage and / or contamination can be caused in particular during the operation of the actuator, but also during the manufacturing process.
• impurities e.g. grinding dust, fingerprints and the like
• moisture e.g. Ag migration or the like
• operating materials e.g. diesel, rapeseed methyl ester and the like
• Passivation is currently produced in such a way that the multilayer ceramic is coated by hand with a passivation material in the form of a self-adhesive silicone compound after the external metallization.
• This silicone elastomer is then cured in a drying cabinet at 150 ° C. for about 30 minutes.
• the actuators thus passivated are then surrounded with a cylindrical plastic jacket using the same silicone elastomer.
• the selection of the passivation material is based on the following criteria:
• the passivation material must have a permanent temperature resistance of> 150 ° C.
• the reason for this lies in the fact that piezoceramic multilayer actuators of the type mentioned, for example as
• Actuators are used in a diesel drive unit that has such a high operating temperature. Furthermore, the passivation material should be as self-adhesive as possible on the multilayer ceramic. Finally, it has hitherto been a prerequisite for passivation materials that they have an elongation at break of> 200% in order to be able to cope with expansions occurring on polarity cracks during actuator operation.
• Piezo actuators in diesel injectors have a serious disadvantage.
• the passivation materials based on silicone that have been used so far are only insufficiently resistant to swelling when wetted with diesel fuel or rapeseed methyl ester (RME).
• the passivation can detach from the surface (s) of the piezoelectric component during operation.
• the present invention is based on the object of specifying a passivation material and a piezoelectric component in a multilayer construction in which the disadvantages described can be avoided.
• a Passivation material and a piezoelectric component are provided, which enables or has a high reliability and service life, preferably also when used in diesel applications.
• a passivation material for an electrical component in particular for a piezoelectric component in multilayer construction, is provided, which is characterized according to the invention in that the passivation material has a tensile strength that is less than the adhesive strength of the passivation material on the electrical component.
• Passivation material on an electrical component creates components with high reliability and durability.
• the invention is not limited to certain types of electrical components. Rather, the passivation material can be used on any form of electrical components that require appropriate passivation.
• the passivation material according to the invention can be used for a piezoelectric component in a multilayer construction, for example a piezoceramic actuator in a multilayer construction mentioned in the introduction to the description. üü c ⁇ K3 MM cn o U1 0 (l 0 c ⁇
• the passivation material can advantageously be formed from at least one plastic.
• any form of polymer which has the material properties according to the invention can be used as a suitable plastic. It is now possible in particular to use polymers which can be produced using alternative coating processes, such as plasma deposition, corona deposition, sputtering, flame CVD and the like.
• the plastic can, for example, be a thermoplastic, which is characterized in that it can assume a thermoplastic state under certain conditions.
• the at least one plastic can be in the form of a higher cross-linked plastic.
• the passivation material can preferably be formed from at least one material which has low-viscosity properties during processing.
• Low-viscosity materials are basically understood to mean those materials which have a low viscosity during their processing, the viscosity generally being a reference quantity for the toughness or internal friction of the material, in particular in liquid or semi-liquid form.
• the passivation material can advantageously be formed from at least one material based on fluorosilicone rubber.
• This is a material that is also available as a liquid system, i.e. as a material with low-viscosity properties during processing.
• Fluorosilicone rubbers also have very good temperature stability, even at low temperatures of up to -40 ° C, and elongation at break, which can be above 200 percent.
• Fluorosilicone rubber shows good media resistance, especially in the media water, diesel oil, rapeseed methyl ester, which is shown by low swelling values even at high operating temperatures. The significance of the degree of swelling will be explained in more detail later in the description.
• the passivation material can be formed, for example, from at least one resin.
• the passivation material can be formed, for example, from at least one resin.
• silicone resins, epoxy resins and the like are conceivable.
• the passivation material can preferably also be formed from at least one material from the group of latices.
• a suitable material here is, for example, but not exclusively, acrylate latex. Such an acrylate latex can advantageously be dispersed in water.
• the passivation material can be formed from at least one material from the group of the polyimides and / or the polyamides and / or the polymethylacrylates and / or the parylene.
• the polyimide can be Kapton, for example.
• Parylene can be obtained, for example, by vapor deposition.
• the passivation material can advantageously each consist of a single one of the materials described above or of several materials in any combination co co ft I- 1 M
• Passivation materials should be found which have a degree of swelling of ⁇ 40 percent, preferably ⁇ 20 percent, very particularly preferably ⁇ 10 percent.
• Storage time of 96 hours only shows a moderate degree of swelling of less than or equal to 40 percent.
• the passivation material advantageously has a permanent temperature resistance of> 150 ° C.
• the passivation material according to the invention has a whole series of advantages over the passivation materials known to date from the prior art, in which the requirement for high ductility had to be met. So are the invention
• Passivation materials are considerably more resistant to swelling, especially in diesel and rapeseed methyl ester.
• the passivation materials according to the invention can have high adhesive strengths on the electrical component, with or without use of connecting means such as adhesion promoters and the like can be done.
• the passivation materials preferably have low-viscosity properties during processing, which in particular facilitates their manufacture and application to the electrical component, for example by means of a casting process or the like.
• the passivation materials according to the invention show crosslinking and / or curing processes that can be optimized in terms of process technology.
• the passivation materials according to the invention can now also be applied to the electrical component by means of alternative coating methods, for example by means of dipping, spraying, CVD (Chemical Vapor Deposition) and the like.
• the passivation materials show a significantly lower permeability for water vapor and other gases as well as a significantly higher electrical insulation and dielectric strength.
• the use of the passivation materials according to the invention on the electrical component also leads to a significant improvement in its functionality and to a simplification of the process engineering implementation.
• a piezoelectric component is provided in a multi-layer construction, in which always one piezoelectric ceramic layer and one alternately
• the electrode layer is arranged one above the other to form a stack, wherein each electrode layer extends at least in regions to at least one lateral surface of the stack, and in which a passivation is provided on this at least one lateral surface.
• the piezoelectric component is characterized in that the passivation is formed from a passivation material according to the invention as described above.
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Landscapes

• Fuel-Injection Apparatus (AREA)
• General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
• Ceramic Capacitors (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

Family

ID=7683335

Family Applications (1)

Country Status (8)

Cited By (6)

Families Citing this family (24)

Family Cites Families (27)

• 2001
  • 2001-04-30 DE DE10121270A patent/DE10121270A1/de not_active Ceased
• 2002
  • 2002-04-18 EP EP02726081A patent/EP1393386B1/de not_active Expired - Lifetime
  • 2002-04-18 WO PCT/DE2002/001444 patent/WO2002089225A2/de not_active Ceased
  • 2002-04-18 CN CNB028091736A patent/CN100373650C/zh not_active Expired - Lifetime
  • 2002-04-18 DE DE50213060T patent/DE50213060D1/de not_active Expired - Lifetime
  • 2002-04-18 AT AT02726081T patent/ATE415709T1/de not_active IP Right Cessation
  • 2002-04-18 US US10/476,209 patent/US6930438B2/en not_active Expired - Lifetime
  • 2002-04-18 JP JP2002586415A patent/JP4465154B2/ja not_active Expired - Lifetime
  • 2002-04-24 TW TW091108460A patent/TW564565B/zh not_active IP Right Cessation

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