WO2020225656A1 - Ceramic resistor, air heating device comprising said ceramic resistor, and method for making said ceramic resistor - Google Patents

Ceramic resistor, air heating device comprising said ceramic resistor, and method for making said ceramic resistor Download PDF

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Publication number
WO2020225656A1
WO2020225656A1 PCT/IB2020/054043 IB2020054043W WO2020225656A1 WO 2020225656 A1 WO2020225656 A1 WO 2020225656A1 IB 2020054043 W IB2020054043 W IB 2020054043W WO 2020225656 A1 WO2020225656 A1 WO 2020225656A1
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WO
WIPO (PCT)
Prior art keywords
ceramic
ceramic layer
layer
conductive track
face
Prior art date
Application number
PCT/IB2020/054043
Other languages
French (fr)
Inventor
Stefano ZAGHI
Pierpaolo Laveni
Original Assignee
Gamma S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gamma S.P.A. filed Critical Gamma S.P.A.
Publication of WO2020225656A1 publication Critical patent/WO2020225656A1/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
    • H05B3/26—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base
    • H05B3/265—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base the insulating base being an inorganic material, e.g. ceramic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R12/00—Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, terminal blocks; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures
    • H01R12/50—Fixed connections
    • H01R12/51—Fixed connections for rigid printed circuits or like structures
    • H01R12/515—Terminal blocks providing connections to wires or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R12/00—Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, terminal blocks; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures
    • H01R12/50—Fixed connections
    • H01R12/51—Fixed connections for rigid printed circuits or like structures
    • H01R12/55—Fixed connections for rigid printed circuits or like structures characterised by the terminals
    • H01R12/57—Fixed connections for rigid printed circuits or like structures characterised by the terminals surface mounting terminals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
    • H01R4/28—Clamped connections, spring connections
    • H01R4/48—Clamped connections, spring connections utilising a spring, clip, or other resilient member
    • H01R4/4809—Clamped connections, spring connections utilising a spring, clip, or other resilient member using a leaf spring to bias the conductor toward the busbar
    • H01R4/48185—Clamped connections, spring connections utilising a spring, clip, or other resilient member using a leaf spring to bias the conductor toward the busbar adapted for axial insertion of a wire end

Definitions

  • This invention relates to a ceramic resistor, an air heating device comprising said ceramic resistor, and a method for making said ceramic resistor.
  • this invention is particularly applicable to the field of small household appliances and, more precisely, to the production and manufacture of the heating components to be inserted inside the blow duct, more preferably of a hair dryer.
  • the invention could also be applied to other sectors that require ceramic resistors that are simple to connect, for example electronically.
  • heating devices In the hair dryer sector, in fact, heating devices generally consist of a support made of insulating and heat-resistant material around which a resistive wire is wound, producing powers that can reach 1200-1500 W.
  • the disadvantage of these applications in addition to the complexity related to making the windings, mainly consists in the need to prepare very long windings and heavy structures necessary to achieve the required performance in terms of heating flows.
  • a first known solution was identified in the use of a self-limiting positive temperature coefficient (PTC) material that, when inserted between two conductive surfaces and equipped with suitable heat exchange fins, can reach temperatures up to 260°C.
  • PTC positive temperature coefficient
  • a second solution of a known type is that of using ceramic resistors as heating elements, defined by an overlapping of ceramic layers between which a conductive filament or track is placed and equipped, if necessary, with appropriate heat exchange fins.
  • known ceramic resistors are connected to the power supply by means of rheophores or contact pins that, starting from the corresponding end portion of the conductive track, rise away from the ceramic substrate and are wound or clamped with the power supply wire.
  • this solution creates many problems during assembly, because in order to make the connection of the power supply wire to the resistor safe, the hair dryer manufacturer must carry out both a winding/clamping step and a welding step. This circumstance is unhelpful both for the manufacturer and for the supplier, who in fact entrusts its customer (manufacturer editor’s note) with a very delicate assembly step that is decisive for the resistor’s functionality.
  • the purpose of this invention is, therefore, to make available a ceramic resistor, an air heating device comprising said ceramic resistor, and a method for making said ceramic resistor that overcome the drawbacks of the above-mentioned prior art.
  • the purpose of this invention is to provide a ceramic resistor with a simple and reliable connection, quick to install inside an air heating device, preferably a hair dryer, hand dryer, or electric heater.
  • the purpose of this invention is also to provide a reliable and easy-to-assemble air heating device.
  • Another purpose of this invention is to provide a particularly efficient and repeatable method for making said ceramic resistor.
  • a ceramic resistor comprising (at least) a first ceramic layer, a second ceramic layer, and a conductive track.
  • the first and the second ceramic layer have respective first and second faces opposite to each other.
  • the conductive track preferably lies on said first ceramic layer and extends between at least two end portions according to a predefined path.
  • the second ceramic layer preferably overlaps the first ceramic layer so that said conductive track is interposed between them.
  • the second ceramic layer has at least two through apertures placed at said at least two end portions of the conductive track in order to make them accessible.
  • the ceramic resistor comprises a pair of metal connectors, each of which is associated with a corresponding through aperture and attached to a corresponding end portion.
  • each connector preferably comprises a base that overlaps and is attached to a respective end portion of the conductive track.
  • This connector also comprises a main body equipped with an insertion portion and a contact portion.
  • the insertion portion defines an entry aperture for an electric wire along an insertion direction.
  • the contact portion is arranged along said insertion direction and is provided with at least two prongs extending in reciprocal approach, defining a gripping point suitable for retaining the electric wire by interlocking it.
  • the ceramic resistor becomes a “quick coupling device”, wherein the electric power supply wires (suitably “stripped”) are each coupled in the corresponding connector without any need for machining and/or welding.
  • the end portions preferably have a thin layer of an alloy containing one or more metals.
  • the thin layer has a contact surface (or exposed surface) with the base of the corresponding metal connector.
  • This contact surface is placed at a distance from the first face of the first ceramic layer that is equal or greater than the distance between the first and the second face of the second ceramic layer.
  • this enables a simple assembly of the connectors.
  • each connector is, preferably, brazed or braze-welded to the corresponding end portion of the conductive track.
  • the end portions have a thin layer of an alloy containing one or more of either: silver, gold, palladium, copper, or nickel.
  • a bonding layer made of a reactive metal, preferably titanium, is placed between the thin layer and the respective end portion.
  • This invention also relates, as mentioned, to a method for making a ceramic resistor, preferably a ceramic resistor as described above.
  • This method preferably involves preparing a heating body comprising a first ceramic layer, a conductive track, and a second ceramic layer according to what is described above.
  • the two metal connectors described above are also prepared.
  • each connector is overlapped on a corresponding end portion of the conductive track and, following this, is welded, preferably braze-welded, to it.
  • this procedure makes it possible to make a ceramic resistor that unites high performance with significant simplicity of assembly.
  • FIG. 1 shows a perspective view of a ceramic resistor according to this invention, according to a first embodiment
  • FIG. 2 shows a perspective, exploded view of the ceramic resistor in Figure 1 ;
  • FIG. 3 shows a perspective, exploded view of a ceramic resistor according to this invention, according to a second embodiment;
  • FIG. 4 shows a side cross-section view of the ceramic resistor in Figure 1 ;
  • Figures 4a and 4b show, respectively, a detail of Figure 4 in cross- section and exploded;
  • FIG. 6a, 6b show, respectively, perspective views of an additional embodiment of a ceramic resistor according to this invention coupled or being coupled to a power supply;
  • FIG. 7 shows a perspective view of an additional embodiment of a ceramic resistor according to this invention.
  • FIG. 8 shows a schematic side view of a hair dryer comprising the ceramic resistor in Figure 7.
  • the number 1 denotes a ceramic resistor according to this invention.
  • ceramic resistor refers, in this document, to an element made by means of a sandwich of at least two ceramic layers, between which a conductive (i.e. resistive) track is placed (and accessible), that heats up by spreading heat over the ceramic layers when subject to a predefined voltage.
  • This ceramic resistor 1 is preferably applied to devices for generating a flow of hot air, preferably in domestic appliances such as hair dryers, hand dryers, paint strippers, or the like, in any case those operating by Joule effect.
  • this device comprises, generally, a main body 101 defining inside a chamber 102 having at least one outlet 103 positioned at one axial end thereof.
  • the ceramic resistor 1 according to the invention is located inside said chamber 102 and electrically connected with a voltage generator 104 provided with at least two electric wires F each extending up to a free end.
  • a voltage generator 104 provided with at least two electric wires F each extending up to a free end.
  • the ceramic resistor 1 comprises a first ceramic layer 2 and a second ceramic layer 4 overlapped on each other along an overlapping axis“A”.
  • first 2 and the second ceramic layer 4 have respective first 2a, 4a and second faces 2b, 4b.
  • the second ceramic layer 4 is overlapped on the first 2 so that the second face 4b thereof abuts against (i.e. overlaps and is in contact with) the first face 2a of the first ceramic layer 2.
  • the first 2 and second ceramic layer 4 extend, thus, in a sheet-like/plate- like way and the overlapping axis “A” is preferably orthogonal to the corresponding first and second faces.
  • the first 2 and the second ceramic layer 4 have a flat, disc or plate-shaped conformation.
  • the first 2 and the second ceramic layer 4 are preferably made of aluminium nitride, suitably distributed, processed, and sintered to determine the final consistency thereof.
  • the materials used to make the ceramic layers could be different, such as, for example, aluminium oxide, or said aluminium (AI203) or silicon nitride (Si3N4).
  • the first 2 and the second ceramic layer 4 can have variable thicknesses depending on the application.
  • Examples of compatible thicknesses with the relevant applications can be in the order of tenths of millimetres, preferably ranging from 0.2 to 0.8 mm.
  • a conductive track 3 lying on the first ceramic layer 2 and extending between at least two end portions 3a according to a predefined path.
  • the ceramic layers 2, 3 and the conductive track 3 define, thus, a heating body 1 a.
  • the conductive track 3 is made/arranged on the first face 2a of the first ceramic layer 2. This conductive track 3, therefore, is interposed (and packed) between the first 2 and the second ceramic layer 4.
  • the conductive track 3 preferably extends between the corresponding end portions 3a with a central portion 3b shaped in a coil (or spiral), turned to maximise the thermal exchange surface with the ceramic layers 2, 4.
  • the shape of the central portion 3b can be variable and depends on the project specifications, both from the point of view of shape and thickness of the track 3.
  • the material with which the conductive track 3 is made can also vary in this case; preferably, in any case, the conductive track 3 is made of tungsten, more preferably it is doped with the same material with which the ceramic layers 2, 4 are made. In the preferred embodiment, thus, the conductive track 3 is made of tungsten doped with a predetermined quantity of aluminium nitrate.
  • This conductive track 3 is preferably made via silkscreen printing on said first ceramic layer 2.
  • the method for making the track is not, in itself, the subject of the invention and examples of this procedure can be found in the prior art, for example in the patents W02006055946 and US20180328624.
  • the end portions 3a of the conductive track preferably have a surface area or width that is significantly greater than the central portion 3b, in order to favour its connection with the electricity supply terminals.
  • the second ceramic layer 4 preferably has at least two through apertures 5 placed at the (at least two) end portions 3a of the conductive track 3.
  • the through apertures 5 are preferably shaped so as to completely expose the end portions 3a.
  • the through apertures 5 are each basically counter-shaped to the corresponding end portion 3a.
  • the ceramic resistor 1 (as well as the heating body 1 a) comprises a plurality of ceramic layers overlapping each other and, at least in part, separated by a plurality of conductive tracks.
  • the ceramic resistor 1 comprises a plurality of second ceramic layers 4 overlapping each other, and one or more additional conductive tracks 13 interposed between each pair of second ceramic layers 4.
  • Each additional conductive track 13 extends between corresponding end portions 13a and is printed (i.e. made) on the first face 4a of a corresponding second ceramic layer 4.
  • the ceramic resistor preferably comprises a plurality of heat exchange fins 14 attached to the heating body 1 a, preferably to the first 2 and/or to the second ceramic layer 4.
  • Possible methods for anchoring the heat exchange fins 14 are known in the art, for example in the documents US20180328624 and WO2018130832.
  • the ceramic resistor comprises at least one pair of metal connectors 6, each of which is associated with a corresponding through aperture 5, fixed to a corresponding end portion 3a of the conductive track.
  • each connector 6 preferably comprises a base 7 and a main body 8, more preferably made of high-melting material, even more preferably, of steel or the like.
  • the base 7 overlaps and is attached to a respective end portion 3a of the conductive track 3.
  • Said base 7 of each connector 6 is preferably counter-shaped to the corresponding through aperture 5.
  • the main body 8 instead, rises from the base to receive an end portion of an electric wire “F” inside, attaching it by interlocking it (i.e. without welding).
  • the main body 8 comprises an insertion portion 8a and a contact portion 8b.
  • the insertion portion 8a defines an entry aperture for the electric wire“F” along an insertion direction“B”.
  • This insertion portion 8a preferably comprises a box-shaped body equipped with an entry aperture and extending circumferentially about said insertion direction“B” to house said electric wire“F” (more precisely one end thereof).
  • the insertion portion 8a could be solely defined by a crossing section for the electric wire“F” directed towards the contact portion 8b.
  • each connector 6 is preferably oriented so that said insertion direction “B” is parallel to an extension plane of said first 2 and second ceramic layer 4.
  • the insertion direction“B” is preferably parallel to the base 7.
  • the contact portion 8b is arranged along said insertion direction“B” and is preferably provided with at least two prongs 9 extending in reciprocal approach, defining a gripping point 10 suitable for retaining the electric wire“F” by interlocking it.
  • the two prongs 9 define a necking of the passage section for the electric wire“F” and have an orientation and structure such as to retain the end of the electric wire“F” (suitably stripped/naked) forced to pass through said necking.
  • the prongs 9 are, thus, shaped so as to give a basically pointed shape to the contact portion 8b.
  • the at least two prongs 9 are preferably tilted in relation to each other in reciprocal approach following the insertion direction“C”.
  • the prongs are suitable for retaining the electric wire “F” by interlocking it.
  • the gripping point 10 is defined, it being suitable for retaining the electric wire“F” by interlocking it.
  • the electrical connector 8 is also equipped with an end stroke portion 8c, defined by a wall of the main body 8a so as to interrupt the advancement of the electric wire“F” along the insertion direction“B”.
  • the end stroke portion 8c defines an obstacle to the advancement of the electric wire“F”.
  • the base 7 of each connector 6 is welded, brazed, or braze-welded to the corresponding end portion 3a of the conductive track 3.
  • the end portions 3a of the track 3 preferably have a thin layer 11 of an alloy containing one or more metals.
  • This metal is preferably nobler than tungsten (or, in any case, of the material with which the track 3 itself is made).
  • This thin layer 11 is preferably made of one of the following metals:
  • the thin layer 1 1 has a contact surface (or exposed surface) with the base 7 of the corresponding metal connector 6.
  • This contact surface is placed at a distance from the first face 2a of the first ceramic layer 2 that is equal or greater than the distance between the first 4a and the second face 4b of the second ceramic layer 4 (or the thickness of the second ceramic layer 4 at least at the aperture).
  • this enables a simple assembly of the connectors.
  • the thin layer 1 1 is defined by a micrometric nickel layer.
  • the attachment between the thin layer 1 1 and the first (or second 4) ceramic layer 2 is favoured, as well as that with the end portion 3a.
  • the base 7 of the connector 6 is attached to the respective end portion 3a“indirectly”, or by means of the thin layer 1 1 and, more preferably, the bonding layer 12.
  • This invention also relates to a method for making a ceramic resistor, preferably (but not necessarily) a ceramic resistor as described above. Therefore, in the following description of the method, and where possible, the same names and the same reference numbers will be used as used in the description of the ceramic resistor 1 carried out so far.
  • the method involves preparing the heating body 1 a and at least two metal connectors 6 having the features previously illustrated.
  • the heating body 1 a preferably comprises the first ceramic layer 2, the conductive track 3, and the second ceramic layer 4.
  • the two metal connectors 6 preferably comprise the base 7 and the main body 8 illustrated above.
  • the two (or more) connectors 6 are positioned above the heating body 1 a.
  • the base 7 of each connector 6 overlaps a corresponding end portion 3a of the conductive track 3 and, according to one aspect of the invention, welded to the end portion 3a.
  • each connector 6 is preferably brazed or braze-welded to the corresponding end portion 3a (or to the layers overlapped on it).
  • the brazing or braze-welding step involves depositing a powder“P” of a filler alloy on said end portions 3a.
  • each connector 6 is overlapped on the corresponding end portion 3a covered with said filler alloy powder P (preferably a material compatible with metals such as nickel or copper). Subsequently, the whole is inserted in a high-temperature oven (preferably > 700°C, more preferably ranging between 800 and 900°C) so as to melt said filler alloy powder P, which has a melting point higher than the connector 6 and the conductive track 3, and welding the base 7 of the connector 6 and the corresponding end portion 3a together.
  • a high-temperature oven preferably > 700°C, more preferably ranging between 800 and 900°C
  • the end portions 3a of the track are covered with thin layer 11 and/or with the bonding layer 12.
  • the method involves one or more preliminary steps of coating the end portions 3a and the subsequent brazing or braze- welding of the bases 7 of the connectors 6 is carried out by depositing the filler alloy powder P and the respective base 7 on the already coated end portions 3a.
  • the step of coating the end portions 3a involves covering these end portions 3a with a thin layer (or thin coating 1 1 ) of an alloy containing one or more metals, preferably selected from among: silver, gold, palladium, copper, and, preferably, nickel.
  • This thin layer 1 1 has (in accordance with what is explained above) an exposed surface at a distance from the first face of the first ceramic layer that is equal or greater than the distance between the first and the second face of the second ceramic layer.
  • an additional coating step is involved, defined by a step of depositing a bonding layer 12 made with a reactive metal, preferably titanium, on each end portion 3a.
  • This depositing step is carried out operatively upstream of the coating step described above (i.e. of the step in which the thin layer 1 1 is made).
  • At least one of either the thin layer 1 1 depositing step or the bonding layer 12 depositing step preferably occurs by means of a cathode pulverisation process (in a vacuum bell).
  • both said steps occur according to said procedure (known in itself).
  • a mask 200 is preferably prepared with at least two through holes 201 (in particular, as many through holes as the end portions 3a of the conductive track 3 or of the additional conductive tracks).
  • a bar or a plate 300, 400 is prepared, made of at least one of the metals listed above (silver, gold, palladium, copper, nickel, titanium, or another reactive metal).
  • a second bar or plate 400 in nobler metal is prepared, preferably nickel, to make the thin layer.
  • the mask 200 is arranged on the heating body 1 a so that only the end portions 3a of the track 3 are accessible through said two through apertures 201.
  • the bar or plate 300, 400 is subjected to a cathode pulverisation process in order to allow the particles 301 , 401 emitted by said bar or plate 300, 400 to be deposited on the end portions 3a inside said at least two holes 201.
  • the cathode pulverisation of the first bar or plate 300 preferably determines the deposit of the respective particles 301 directly on the end portion 3a.
  • the cathode pulverisation of the second bar or plate 400 determines, instead, the depositing of the respective particles 401 on the bonding layer 12 (if present).
  • the invention achieves its intended purposes and significant advantages are thus obtained.
  • the process of attaching the connectors in successive steps is particularly effective, the steps involving first coating the end portions with material suitable for increasing the adhesion with the ceramics and/or the compatibility with brazing or braze-welding processes.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Resistance Heating (AREA)

Abstract

A ceramic resistor, comprises a first ceramic layer (2), a conductive track (3) extending between at least two end portions (3a) according to a predefined path and a second ceramic layer (4) overlapping the first ceramic layer (2) and having at least two through apertures (5) placed at the at least two end portions (3a) of the conductive track (3). The ceramic resistor also comprises a pair of metal connectors (6) each associated with a respective through aperture (5) and comprising a base (7) overlapping and attached to a respective end portion (3a) of the conductive track (3) and a main body (8) defining a gripping point (10) suitable for retaining the electric wire (F) by interlocking it.

Description

DESCRIPTION
“CERAMIC RESISTOR, AIR HEATING DEVICE COMPRISING SAID CERAMIC RESISTOR, AND METHOD FOR MAKING SAID CERAMIC
RESISTOR”
This invention relates to a ceramic resistor, an air heating device comprising said ceramic resistor, and a method for making said ceramic resistor.
Therefore, this invention is particularly applicable to the field of small household appliances and, more precisely, to the production and manufacture of the heating components to be inserted inside the blow duct, more preferably of a hair dryer.
Alternatively, the invention could also be applied to other sectors that require ceramic resistors that are simple to connect, for example electronically.
That said, for the sake of descriptive simplicity, explicit reference will be made below to hair dryers as a sector of particular interest to the Applicant, it being understood that, where technically applicable, everything described with explicit reference to a hair dryer is also applicable, mutatis mutandis, to a different device for generating a flow of hot air operating by Joule effect.
In the hair dryer sector, in fact, heating devices generally consist of a support made of insulating and heat-resistant material around which a resistive wire is wound, producing powers that can reach 1200-1500 W. The disadvantage of these applications, in addition to the complexity related to making the windings, mainly consists in the need to prepare very long windings and heavy structures necessary to achieve the required performance in terms of heating flows.
For this reason, in recent years, other solutions have been investigated that, from a performance point of view, would make it possible to achieve a high degree of heating with limited dimensions and masses. A first known solution was identified in the use of a self-limiting positive temperature coefficient (PTC) material that, when inserted between two conductive surfaces and equipped with suitable heat exchange fins, can reach temperatures up to 260°C.
The limited performance in terms of power, however, requires the use of many of these devices in series, which negatively impacts the weight and size on the hair dryer.
A second solution of a known type is that of using ceramic resistors as heating elements, defined by an overlapping of ceramic layers between which a conductive filament or track is placed and equipped, if necessary, with appropriate heat exchange fins.
Examples of such solutions are known for example from the patents WO200655946 and WO2018130798, wherein variously shaped resistors, suitable for use in various types of hair dryers, are presented.
As can be deduced from these documents, however, the ceramic resistors of the prior art have some critical issues related to their electrical connectivity with batteries and/or power electronics.
In this regard, in fact, known ceramic resistors (but not only ceramic-type resistors) are connected to the power supply by means of rheophores or contact pins that, starting from the corresponding end portion of the conductive track, rise away from the ceramic substrate and are wound or clamped with the power supply wire.
Disadvantageously, this solution creates many problems during assembly, because in order to make the connection of the power supply wire to the resistor safe, the hair dryer manufacturer must carry out both a winding/clamping step and a welding step. This circumstance is unhelpful both for the manufacturer and for the supplier, who in fact entrusts its customer (manufacturer editor’s note) with a very delicate assembly step that is decisive for the resistor’s functionality.
The purpose of this invention is, therefore, to make available a ceramic resistor, an air heating device comprising said ceramic resistor, and a method for making said ceramic resistor that overcome the drawbacks of the above-mentioned prior art.
In particular, the purpose of this invention is to provide a ceramic resistor with a simple and reliable connection, quick to install inside an air heating device, preferably a hair dryer, hand dryer, or electric heater.
Therefore, the purpose of this invention is also to provide a reliable and easy-to-assemble air heating device.
In addition, another purpose of this invention is to provide a particularly efficient and repeatable method for making said ceramic resistor.
Said purposes are achieved with a ceramic resistor having the features of one or more of the subsequent claims from 1 to 10, an air heating device having the features of claim 11 , and a method of making said ceramic resistor having the technical features of one or more of the claims from 12 to 16.
In particular, the purposes of this invention are achieved with a ceramic resistor, comprising (at least) a first ceramic layer, a second ceramic layer, and a conductive track.
The first and the second ceramic layer have respective first and second faces opposite to each other.
The conductive track preferably lies on said first ceramic layer and extends between at least two end portions according to a predefined path.
In addition, the second ceramic layer preferably overlaps the first ceramic layer so that said conductive track is interposed between them.
More preferably, the second ceramic layer has at least two through apertures placed at said at least two end portions of the conductive track in order to make them accessible.
According to one aspect of the invention, the ceramic resistor comprises a pair of metal connectors, each of which is associated with a corresponding through aperture and attached to a corresponding end portion.
In this respect, each connector preferably comprises a base that overlaps and is attached to a respective end portion of the conductive track. This connector also comprises a main body equipped with an insertion portion and a contact portion.
The insertion portion defines an entry aperture for an electric wire along an insertion direction.
The contact portion is arranged along said insertion direction and is provided with at least two prongs extending in reciprocal approach, defining a gripping point suitable for retaining the electric wire by interlocking it.
Advantageously, in this way the ceramic resistor becomes a “quick coupling device”, wherein the electric power supply wires (suitably “stripped”) are each coupled in the corresponding connector without any need for machining and/or welding.
In addition, the end portions preferably have a thin layer of an alloy containing one or more metals.
The thin layer has a contact surface (or exposed surface) with the base of the corresponding metal connector.
This contact surface is placed at a distance from the first face of the first ceramic layer that is equal or greater than the distance between the first and the second face of the second ceramic layer.
Advantageously, this enables a simple assembly of the connectors.
On the one hand, this results in an enormous advantage for the manufacturer of the devices, which simply need a linear actuator adapted to the coupling to automate the assembly. On the other hand, the supplier (i.e. the resistor manufacturer) is able to supply a product the performance of which entirely depends on the internal processes, being able to ensure performance without risk of complaint.
The base of each connector is, preferably, brazed or braze-welded to the corresponding end portion of the conductive track.
More preferably, the end portions have a thin layer of an alloy containing one or more of either: silver, gold, palladium, copper, or nickel.
Advantageously, it is thus possible to favour the anchoring of the base to the end portion, since the metals listed above are particularly compatible with welding/brazing/braze-welding processes.
In addition, in the preferred embodiment, a bonding layer made of a reactive metal, preferably titanium, is placed between the thin layer and the respective end portion.
Advantageously, this favours the anchoring of the thin layer (preferably nickel) not only to the end portion, but also to the ceramic material that surrounds it.
This invention also relates, as mentioned, to a method for making a ceramic resistor, preferably a ceramic resistor as described above.
This method preferably involves preparing a heating body comprising a first ceramic layer, a conductive track, and a second ceramic layer according to what is described above.
The two metal connectors described above are also prepared.
At this point, the base of each connector is overlapped on a corresponding end portion of the conductive track and, following this, is welded, preferably braze-welded, to it.
Advantageously, this procedure, as well as being simple and repeatable in itself, makes it possible to make a ceramic resistor that unites high performance with significant simplicity of assembly.
These and other features, together with the related advantages, will be clearer from the following illustrative, and therefore non-limiting, description of a preferred, and thus non-exclusive, embodiment of a ceramic resistor, an air heating device comprising said ceramic resistor, and a method for making said ceramic resistor according to what is shown in the attached drawings, wherein:
- Figure 1 shows a perspective view of a ceramic resistor according to this invention, according to a first embodiment;
- Figure 2 shows a perspective, exploded view of the ceramic resistor in Figure 1 ; - Figure 3 shows a perspective, exploded view of a ceramic resistor according to this invention, according to a second embodiment;
- Figure 4 shows a side cross-section view of the ceramic resistor in Figure 1 ;
- Figures 4a and 4b show, respectively, a detail of Figure 4 in cross- section and exploded;
- Figures 5a-5e schematically show successive steps of a method for making a ceramic resistor according to this invention;
- Figures 6a, 6b show, respectively, perspective views of an additional embodiment of a ceramic resistor according to this invention coupled or being coupled to a power supply;
- Figure 7 shows a perspective view of an additional embodiment of a ceramic resistor according to this invention;
- Figure 8 shows a schematic side view of a hair dryer comprising the ceramic resistor in Figure 7.
With reference to the attached figures, the number 1 denotes a ceramic resistor according to this invention.
The expression“ceramic resistor” refers, in this document, to an element made by means of a sandwich of at least two ceramic layers, between which a conductive (i.e. resistive) track is placed (and accessible), that heats up by spreading heat over the ceramic layers when subject to a predefined voltage.
This ceramic resistor 1 is preferably applied to devices for generating a flow of hot air, preferably in domestic appliances such as hair dryers, hand dryers, paint strippers, or the like, in any case those operating by Joule effect.
With reference to the hair dryer 100, for example, this device comprises, generally, a main body 101 defining inside a chamber 102 having at least one outlet 103 positioned at one axial end thereof.
The ceramic resistor 1 according to the invention is located inside said chamber 102 and electrically connected with a voltage generator 104 provided with at least two electric wires F each extending up to a free end. As already mentioned above, for simplicity of description, explicit reference was made to hair dryers as the sector of particular interest for the Applicant. In any case, what was described with explicit reference to these devices will be valid, mutatis mutandis, and where technically applicable, to a different device for generating a flow of hot air operating by Joule effect as well.
Returning to the ceramic resistor 1 , it comprises a first ceramic layer 2 and a second ceramic layer 4 overlapped on each other along an overlapping axis“A”.
In particular, in the preferred embodiment, the first 2 and the second ceramic layer 4 have respective first 2a, 4a and second faces 2b, 4b.
The second ceramic layer 4 is overlapped on the first 2 so that the second face 4b thereof abuts against (i.e. overlaps and is in contact with) the first face 2a of the first ceramic layer 2.
The first 2 and second ceramic layer 4 extend, thus, in a sheet-like/plate- like way and the overlapping axis “A” is preferably orthogonal to the corresponding first and second faces.
In the preferred embodiment, the first 2 and the second ceramic layer 4 have a flat, disc or plate-shaped conformation.
Alternatively, in any case, other shapes could be used, both curved or of another kind.
The first 2 and the second ceramic layer 4 are preferably made of aluminium nitride, suitably distributed, processed, and sintered to determine the final consistency thereof.
Alternatively, the materials used to make the ceramic layers could be different, such as, for example, aluminium oxide, or said aluminium (AI203) or silicon nitride (Si3N4).
Methods for making and coupling the ceramic layers are known in themselves and can be found in the literature, for example, in the patents US6986865 and US9340462. From the point of view of size, the first 2 and the second ceramic layer 4 can have variable thicknesses depending on the application. Examples of compatible thicknesses with the relevant applications can be in the order of tenths of millimetres, preferably ranging from 0.2 to 0.8 mm.
In order to make the resistor 1 controllable and efficient, there is a conductive track 3 lying on the first ceramic layer 2 and extending between at least two end portions 3a according to a predefined path. The ceramic layers 2, 3 and the conductive track 3 define, thus, a heating body 1 a.
More precisely, the conductive track 3 is made/arranged on the first face 2a of the first ceramic layer 2. This conductive track 3, therefore, is interposed (and packed) between the first 2 and the second ceramic layer 4.
The conductive track 3 preferably extends between the corresponding end portions 3a with a central portion 3b shaped in a coil (or spiral), turned to maximise the thermal exchange surface with the ceramic layers 2, 4.
The shape of the central portion 3b can be variable and depends on the project specifications, both from the point of view of shape and thickness of the track 3.
The material with which the conductive track 3 is made can also vary in this case; preferably, in any case, the conductive track 3 is made of tungsten, more preferably it is doped with the same material with which the ceramic layers 2, 4 are made. In the preferred embodiment, thus, the conductive track 3 is made of tungsten doped with a predetermined quantity of aluminium nitrate.
This conductive track 3 is preferably made via silkscreen printing on said first ceramic layer 2. In this case too, the method for making the track is not, in itself, the subject of the invention and examples of this procedure can be found in the prior art, for example in the patents W02006055946 and US20180328624. The end portions 3a of the conductive track preferably have a surface area or width that is significantly greater than the central portion 3b, in order to favour its connection with the electricity supply terminals.
In this respect, the second ceramic layer 4 preferably has at least two through apertures 5 placed at the (at least two) end portions 3a of the conductive track 3.
The through apertures 5 are preferably shaped so as to completely expose the end portions 3a.
In the preferred embodiment, the through apertures 5 are each basically counter-shaped to the corresponding end portion 3a.
It should also be noted that, in some embodiments, the ceramic resistor 1 (as well as the heating body 1 a) comprises a plurality of ceramic layers overlapping each other and, at least in part, separated by a plurality of conductive tracks.
In a preferred embodiment, in fact, the ceramic resistor 1 comprises a plurality of second ceramic layers 4 overlapping each other, and one or more additional conductive tracks 13 interposed between each pair of second ceramic layers 4. Each additional conductive track 13 extends between corresponding end portions 13a and is printed (i.e. made) on the first face 4a of a corresponding second ceramic layer 4.
Additional variants, both in relation to the number of layers and of conductive tracks, are possible and encompassed within the spirit of this invention.
In addition, in these embodiments, the ceramic resistor preferably comprises a plurality of heat exchange fins 14 attached to the heating body 1 a, preferably to the first 2 and/or to the second ceramic layer 4. Possible methods for anchoring the heat exchange fins 14 are known in the art, for example in the documents US20180328624 and WO2018130832.
According to one main aspect of this invention, the ceramic resistor comprises at least one pair of metal connectors 6, each of which is associated with a corresponding through aperture 5, fixed to a corresponding end portion 3a of the conductive track.
In this respect, each connector 6 preferably comprises a base 7 and a main body 8, more preferably made of high-melting material, even more preferably, of steel or the like.
The base 7 overlaps and is attached to a respective end portion 3a of the conductive track 3.
Said base 7 of each connector 6 is preferably counter-shaped to the corresponding through aperture 5.
The main body 8, instead, rises from the base to receive an end portion of an electric wire “F” inside, attaching it by interlocking it (i.e. without welding).
More precisely, the main body 8 comprises an insertion portion 8a and a contact portion 8b.
The insertion portion 8a defines an entry aperture for the electric wire“F” along an insertion direction“B”.
This insertion portion 8a preferably comprises a box-shaped body equipped with an entry aperture and extending circumferentially about said insertion direction“B” to house said electric wire“F” (more precisely one end thereof).
Alternatively, in any case, the insertion portion 8a could be solely defined by a crossing section for the electric wire“F” directed towards the contact portion 8b.
It should be noted that the main body 8 and/or the insertion portion 8a of each connector 6 are preferably oriented so that said insertion direction “B” is parallel to an extension plane of said first 2 and second ceramic layer 4.
Thus, the insertion direction“B” is preferably parallel to the base 7.
The contact portion 8b is arranged along said insertion direction“B” and is preferably provided with at least two prongs 9 extending in reciprocal approach, defining a gripping point 10 suitable for retaining the electric wire“F” by interlocking it.
In other words, the two prongs 9 define a necking of the passage section for the electric wire“F” and have an orientation and structure such as to retain the end of the electric wire“F” (suitably stripped/naked) forced to pass through said necking.
The prongs 9 are, thus, shaped so as to give a basically pointed shape to the contact portion 8b. The at least two prongs 9 are preferably tilted in relation to each other in reciprocal approach following the insertion direction“C”. Thus, the prongs are suitable for retaining the electric wire “F” by interlocking it. In other words, where the prongs reach maximum proximity to each other, the gripping point 10 is defined, it being suitable for retaining the electric wire“F” by interlocking it.
According to a preferred embodiment, in addition, the electrical connector 8 is also equipped with an end stroke portion 8c, defined by a wall of the main body 8a so as to interrupt the advancement of the electric wire“F” along the insertion direction“B”. In other words, the end stroke portion 8c defines an obstacle to the advancement of the electric wire“F”.
One embodiment of the electrical connector 8 is described, though with a completely different application, in the patent GB2516555.
According to another aspect of the invention, the base 7 of each connector 6 is welded, brazed, or braze-welded to the corresponding end portion 3a of the conductive track 3.
The end portions 3a of the track 3 preferably have a thin layer 11 of an alloy containing one or more metals.
This metal is preferably nobler than tungsten (or, in any case, of the material with which the track 3 itself is made).
This thin layer 11 is preferably made of one of the following metals:
- silver,
- gold,
- palladium,
- copper, - nickel.
According to one aspect of the invention, the thin layer 1 1 has a contact surface (or exposed surface) with the base 7 of the corresponding metal connector 6.
This contact surface is placed at a distance from the first face 2a of the first ceramic layer 2 that is equal or greater than the distance between the first 4a and the second face 4b of the second ceramic layer 4 (or the thickness of the second ceramic layer 4 at least at the aperture).
Advantageously, this enables a simple assembly of the connectors.
In the preferred embodiment, the thin layer 1 1 is defined by a micrometric nickel layer.
This advantageously favours the stability of the welding/brazing/braze- welding.
More preferably, a bonding layer 12 made of a reactive metal, preferably titanium, is placed between said thin layer 1 1 and the respective end portion 3a.
Advantageously, in this way, the attachment between the thin layer 1 1 and the first (or second 4) ceramic layer 2 is favoured, as well as that with the end portion 3a.
Therefore, in the preferred embodiment, the base 7 of the connector 6 is attached to the respective end portion 3a“indirectly”, or by means of the thin layer 1 1 and, more preferably, the bonding layer 12.
This invention also relates to a method for making a ceramic resistor, preferably (but not necessarily) a ceramic resistor as described above. Therefore, in the following description of the method, and where possible, the same names and the same reference numbers will be used as used in the description of the ceramic resistor 1 carried out so far.
In the following, therefore, where the features illustrated refer to the structural features of the ceramic resistor 1 , what has been claimed beforehand is to be considered as applicable, mutatis mutandis.
The method involves preparing the heating body 1 a and at least two metal connectors 6 having the features previously illustrated.
Therefore, the heating body 1 a preferably comprises the first ceramic layer 2, the conductive track 3, and the second ceramic layer 4.
In the same way, the two metal connectors 6 preferably comprise the base 7 and the main body 8 illustrated above.
The two (or more) connectors 6 are positioned above the heating body 1 a. In particular, the base 7 of each connector 6 overlaps a corresponding end portion 3a of the conductive track 3 and, according to one aspect of the invention, welded to the end portion 3a.
The base 7 of each connector 6 is preferably brazed or braze-welded to the corresponding end portion 3a (or to the layers overlapped on it).
The brazing or braze-welding step involves depositing a powder“P” of a filler alloy on said end portions 3a.
At this point, the base 7 of each connector 6 is overlapped on the corresponding end portion 3a covered with said filler alloy powder P (preferably a material compatible with metals such as nickel or copper). Subsequently, the whole is inserted in a high-temperature oven (preferably > 700°C, more preferably ranging between 800 and 900°C) so as to melt said filler alloy powder P, which has a melting point higher than the connector 6 and the conductive track 3, and welding the base 7 of the connector 6 and the corresponding end portion 3a together.
It should be noted that, in preferred embodiments, the end portions 3a of the track are covered with thin layer 11 and/or with the bonding layer 12.
In these embodiments, the method involves one or more preliminary steps of coating the end portions 3a and the subsequent brazing or braze- welding of the bases 7 of the connectors 6 is carried out by depositing the filler alloy powder P and the respective base 7 on the already coated end portions 3a.
More specifically, the step of coating the end portions 3a involves covering these end portions 3a with a thin layer (or thin coating 1 1 ) of an alloy containing one or more metals, preferably selected from among: silver, gold, palladium, copper, and, preferably, nickel.
This thin layer 1 1 has (in accordance with what is explained above) an exposed surface at a distance from the first face of the first ceramic layer that is equal or greater than the distance between the first and the second face of the second ceramic layer.
More preferably, an additional coating step is involved, defined by a step of depositing a bonding layer 12 made with a reactive metal, preferably titanium, on each end portion 3a.
This depositing step is carried out operatively upstream of the coating step described above (i.e. of the step in which the thin layer 1 1 is made).
At least one of either the thin layer 1 1 depositing step or the bonding layer 12 depositing step preferably occurs by means of a cathode pulverisation process (in a vacuum bell).
More preferably, both said steps occur according to said procedure (known in itself).
Specifically, a mask 200 is preferably prepared with at least two through holes 201 (in particular, as many through holes as the end portions 3a of the conductive track 3 or of the additional conductive tracks).
A bar or a plate 300, 400 is prepared, made of at least one of the metals listed above (silver, gold, palladium, copper, nickel, titanium, or another reactive metal).
More precisely, a first bar or plate 300 made of reactive metal, preferably titanium, is prepared to make the bonding layer 12.
In addition, a second bar or plate 400 in nobler metal (silver, gold, palladium, copper, nickel) is prepared, preferably nickel, to make the thin layer.
The mask 200 is arranged on the heating body 1 a so that only the end portions 3a of the track 3 are accessible through said two through apertures 201.
Finally, preferably inside a vacuum bell, the bar or plate 300, 400 is subjected to a cathode pulverisation process in order to allow the particles 301 , 401 emitted by said bar or plate 300, 400 to be deposited on the end portions 3a inside said at least two holes 201.
Specifically, the cathode pulverisation of the first bar or plate 300 preferably determines the deposit of the respective particles 301 directly on the end portion 3a.
The cathode pulverisation of the second bar or plate 400 determines, instead, the depositing of the respective particles 401 on the bonding layer 12 (if present).
The invention achieves its intended purposes and significant advantages are thus obtained.
In fact, providing ceramic resistors equipped with“interlocking” connectors and without welding makes the product much more appealing on the market and considerably facilitates the assembly thereof.
Moreover, the peculiar feature of braze-welding the bases of the connectors to the ends of the track makes it possible to create a strong and low-defect connection.
In this respect, the process of attaching the connectors in successive steps is particularly effective, the steps involving first coating the end portions with material suitable for increasing the adhesion with the ceramics and/or the compatibility with brazing or braze-welding processes.

Claims

1. A ceramic resistor, comprising:
- a first ceramic layer (2) having a first (2a) and a second face (2b) opposite to each other;
- a conductive track (3) lying on the first face (2a) of said first ceramic layer (2) and extending between at least two end portions (3a) according to a predefined path;
- a second ceramic layer (4) having a first (4a) and a second face (4b) opposite to each other; said second ceramic layer (4) overlapping said first ceramic layer (2) so that the second face of the (4b) second ceramic layer (4) overlaps the first face (2a) of the first ceramic layer (2) and said conductive track (3) is interposed between said first (2) and second ceramic layer (4), wherein the second ceramic layer (4) has at least two through apertures (5) placed at said at least two end portions (3a) of the conductive track (3);
characterised in that it comprises a pair of metal connectors (6) each associated with a respective through aperture (5) and comprising:
- a base (7) overlapping and attached to a respective end portion (3a) of the conductive track (3);
- a main body (8) provided with an insertion portion (8a), defining an entry aperture for an electric wire (F) along an insertion direction (B) and a contact portion (8b), arranged along said insertion direction (B) and provided with at least two prongs (9) extending in reciprocal approach defining a gripping point (10) for retaining the electric wire (F) by interlocking it,
wherein said end portions (3a) of the conductive track (3) have a thin layer (1 1 ) of an alloy containing one or more metals,
and wherein said thin layer (1 1 ) comprises a contact surface with the base (7) of the relative metal connector (6) that is set at a distance from the first face (2a) of the first ceramic layer (2) equal or greater than the distance between the first (4a) and second face (4b) of said second ceramic layer (4).
2. The ceramic resistor according to claim 1 , wherein said base (7) of each connector (6) is braze-welded to the corresponding end portion (3a) of the conductive track (3).
3. The ceramic resistor according to claim 1 or 2, wherein said base (7) of each connector (6) is counter-shaped to the respective through aperture
(5).
4. The ceramic resistor according to any one of the previous claims, wherein said main body (8) of each connector (6) is oriented so that said insertion direction (B) is parallel to an extension plane of said first (2) and second ceramic layer (4).
5. The ceramic resistor according to any one of the previous claims, wherein said first (2) and second ceramic layers (4) are made of aluminium nitride.
6. The ceramic resistor according to any one of the previous claims, wherein said conductive track (3) comprises a coil (3b) extending between said end portions (3a) and made of tungsten, preferably doped with aluminium nitride.
7. The ceramic resistor according to any one of the previous claims, wherein said conductive track (3) is made by silkscreen printing on said first ceramic layer (2).
8. The ceramic resistor according to any one of the preceding claims, wherein said thin layer (1 1 ) is made with an alloy containing one or more of the following metals: - silver,
- gold,
- palladium,
- copper,
- nickel.
9. The ceramic resistor according to claim 8, wherein a bonding layer (12) made of a reactive metal, preferably titanium, is placed between said thin layer (1 1 ) and the respective end portion (3a).
10. The ceramic resistor according to any one of the previous claims, comprising a plurality of second ceramic layers (4) overlapping each other, and one or more additional conductive tracks (13) interposed between each pair of second ceramic layers (4).
11. A device for generating a flow of hot air, preferably a hair dryer, hand dryer, electric heater, or paint remover, comprising:
- a main body (101 ) defining inside a chamber (102) having at least one outlet (103) positioned at one of its axial ends;
- a ceramic resistor (1 ) according to any one of the claims from 1 to 8 located inside said chamber;
- a voltage generator (104) provided with at least two electrical wires (F) each extending as far as a free end engaged by interlocking in said contact portion (8b) of a respective connector (6).
12. A method of making a ceramic resistor, comprising the steps of:
- providing a heating body (1 a) comprising
a first ceramic layer (2) having a first (2a) and a second face (2b) opposite to each other,
a conductive track (3) lying on the first face (2a) of said first ceramic layer (2) and extending between at least two end portions (3a) according to a predefined path and
a second ceramic layer (4) having a first (4a) and a second face (4b) opposite to each other; said second ceramic layer (4) overlapping said first ceramic layer (2) so that the second face of the (4b) second ceramic layer (4) overlaps the first face (2a) of the first ceramic layer (2) and said conductive track (3) is interposed between said first (2) and second ceramic layer (4), wherein the second ceramic layer (4) has at least two through apertures (5) placed at said at least two end portions (3a) of the conductive track (3);
- providing two metal connectors (6) comprising a base (7) and a main body (8) provided with an insertion portion (8a), defining an entry aperture for an electric wire (F) along an insertion direction (B) and a contact portion (8b), arranged along said insertion direction (B) and provided with at least two prongs (9) extending in reciprocal approach defining a gripping point (10) suitable for retaining the electric wire (F) by interlocking it;
- coating said end portions (3a) with a thin layer (1 1 ) of an alloy containing one or more metals, wherein said thin layer (1 1 ) has an exposed surface set at a distance from the first face (2a) of the first ceramic layer (2) equal or greater than the distance between the first (4a) and second face (4b) of said second ceramic layer (4);
- overlapping said base (7) of each connector (6) on a respective end portion (3a) of said conductive track (3);
- welding said base (7) to said end portion (3a).
13. The method according to claim 12, wherein said welding step provides for welding or braze-welding the base (7) of the connector (6) to the end portion (3a) by means of:
- depositing a filler alloy powder (P) at said end portions (3a), said filler alloy having a lower melting point than said connector (6) and said conductive track (3); - overlapping the base (7) of each connector (6) on the respective end portion (3a) coated with said filler alloy powder (P);
- drying in a high-temperature oven in order to melt said filler alloy powder (P) and to weld the base (7) of the connector (6) and the respective end portion (3a) together.
14. The method according to claim 12 or 13, wherein said thin layer (1 1 ) is made of an alloy containing one or more of the following metals:
- silver,
- gold,
- palladium,
- copper,
- nickel;
15. The method according to claim 14, further comprising a depositing step, performed prior to said coating step, wherein a bonding layer (12) made of a reactive metal, preferably titanium, is deposited on each end portion (3a).
16. The method according to claim 14 or 15, wherein said coating step and/or said depositing step wherein a bonding layer (12) is deposited involve:
- preparing a mask (200) with two through apertures (201 );
- preparing a bar or plate (300, 400) of at least one of the following metals: silver, gold, palladium, copper, nickel, or titanium;
- placing said mask (200) on said heating body so that only the end portions (3a) of the track (3) are accessible through said two through apertures (201 );
- subjecting said bar or plate (300, 400) to a process of cathode pulverisation in order to allow the particles (301 , 401 ) emitted by said bar or plate (300, 400) to be deposited on the end portions (3a) inside said at least two holes (201).
PCT/IB2020/054043 2019-05-08 2020-04-29 Ceramic resistor, air heating device comprising said ceramic resistor, and method for making said ceramic resistor WO2020225656A1 (en)

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IT102019000006652A IT201900006652A1 (en) 2019-05-08 2019-05-08 CERAMIC RESISTANCE, AIR HEATING DEVICE INCLUDING SAID CERAMIC RESISTANCE AND METHOD OF REALIZATION OF SAID CERAMIC RESISTANCE
IT102019000006652 2019-05-08

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GB2516555A (en) * 2013-06-26 2015-01-28 Avx Corp Single element wire to board connector
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WO2006055946A1 (en) 2004-11-19 2006-05-26 Conair Corporation Hair dryers containing high-watt density ceramic heaters
JP2015514661A (en) 2012-02-29 2015-05-21 ハリス，ジョナサン・エイチ Transient liquid phase, normal pressure bonding of aluminum nitride parts
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FR2910246A3 (en) * 2006-12-26 2008-06-27 Duna Entpr Sa Heating pad for use in smooth hair iron device, has pair of laminar plates for insulating electricity, and body including adaptation unit that adapts pad to support structure of hair iron device, where unit is formed by sliding guide
GB2516555A (en) * 2013-06-26 2015-01-28 Avx Corp Single element wire to board connector
WO2018130832A1 (en) * 2017-01-12 2018-07-19 Dyson Technology Limited A hand held appliance

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