WO1996017496A1 - Perfectionnements apportes a des elements a couche epaisse - Google Patents

Perfectionnements apportes a des elements a couche epaisse Download PDF

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Publication number
WO1996017496A1
WO1996017496A1 PCT/GB1995/002751 GB9502751W WO9617496A1 WO 1996017496 A1 WO1996017496 A1 WO 1996017496A1 GB 9502751 W GB9502751 W GB 9502751W WO 9617496 A1 WO9617496 A1 WO 9617496A1
Authority
WO
WIPO (PCT)
Prior art keywords
tracks
thick film
resistive
compensating
resistance
Prior art date
Application number
PCT/GB1995/002751
Other languages
English (en)
Inventor
Peter James Little
Original Assignee
Pifco Limited
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 Pifco Limited filed Critical Pifco Limited
Priority to DE69502630T priority Critical patent/DE69502630T2/de
Priority to EP95937110A priority patent/EP0793898B1/fr
Priority to NZ295712A priority patent/NZ295712A/en
Priority to AU39315/95A priority patent/AU694815B2/en
Publication of WO1996017496A1 publication Critical patent/WO1996017496A1/fr

Links

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
    • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
    • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
    • H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
    • 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
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/002—Heaters using a particular layout for the resistive material or resistive elements
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/013—Heaters using resistive films or coatings
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/017—Manufacturing methods or apparatus for heaters
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/021—Heaters specially adapted for heating liquids

Definitions

  • the present invention relates to thick film resistive heating elements such as can be used particularly but not exclusively in liquid heating appliances such as water boilers, kettles and the like.
  • thick film resistive heating elements are manufactured by printing a thick film resistive track on to the surface of an electrically insulative substrate.
  • the length, width and thickness of the printed track and the resistivity of the track material determines its resistance.
  • the length and width of the track are relatively simple to control, the thickness is more difficult to control, for example because of irregularities in the surface of the underlying substrate.
  • variations in the printing and resistivity of such thick film resistive tracks can cause the measured resistance of any given track layout to vary by up to ⁇ 15% from a desired level.
  • the object of the present invention is provide a thick film resistive heating element and a method of producing same which overcomes or substantially mitigates the aforementioned problem.
  • a method of manufacturing a thick film resistive heating element comprising the steps of applying one or more thick film resistive tracks to the surface of an electrically insulative substrate; applying at least one compensating thick film resistive track to the surface of the substrate but electrically disconnected from said one or more thick film resistive tracks at the time of application; measuring the resistance of said one or more resistive tracks excluding the one or more compensating tracks; determining whether the measured resistance varies from a predetermined required value by more than a permitted tolerance; and electrically connecting at least one of the compensating resistive tracks to said one or more resistive tracks to vary the resistance of the tracks in the event of the measured resistance falling outside said permitted tolerance.
  • each compensating thick film resistive track is printed in parallel with said one or more resistive tracks whereby electrical connection of one or more of the compensating tracks to said one or more resistive tracks decreases the resistance of the electrically connected resistive tracks as a whole.
  • the width, length and thickness of said one or more thick film resistive tracks are predetermined so that the measured resistance will on average be higher than the predetermined required value, and the width, length and thickness of each compensating track is predetermined so that its resistance is on average such that when electrically connected in parallel to said one or more thick film resistive tracks the measured resistance of the electrically connected resistive tracks as a whole will only vary from the predetermined required value by an amount no more than the permitted tolerance.
  • the method comprises the additional step of applying an encapsulating insulating layer over all the resistive tracks and the substrate to protect and insulate same.
  • a thick film resistive heating element comprising at one or more thick film resistive tracks applied to the surface of an electrically insulative substrate and characterised in that at least one compensating thick film resistive track is applied to the surface of the substrate in parallel with said one or more resistive tracks but electrically disconnected therefrom at the time of application.
  • a thick film resistive heating element 1 is formed by applying a first dielectric adhesion layer to a rigid substrate 2, such as a stainless steel plate, the adhesion layer being selected to have a coefficient of thermal expansion approximately equal to that of the steel.
  • a rigid substrate 2 such as a stainless steel plate
  • One or more further separate coatings are then separately applied such that the final coating has a coefficient of thermal expansion approximately equal to a thick film ink.
  • a thick film circuit layout is then applied by silk- screen printing in which a conductive track 3 constituting the heating element is printed.
  • the track is preferably formed of palladium silver but may alternatively be made of other conducting materials such as nickel, platinum, silver, or carbon, for example.
  • the track 3 follows a tortuous path of predetermined length over the majority of the area of the substrate 2 to maximise the heated area of the element 1.
  • the track 3 terminates in respective contact portions 4 and 5 which are adapted to make electrical connection with an electrical control device for the element 1.
  • Thick film resistive tracks such as the track 3 are usually deposited on the insulated substrate 1 at a constant thickness of between approximately 10 to 14 microns.
  • the width of the track may be varied to vary its resistance. Its resistance is reduced by increasing the width of the track and correspondingly increased by reducing the width of the track.
  • the track 3 is formed by a pair of parallel tracks 3A and 3B.
  • a track 3 can be printed with a predetermined length and width and with a predetermined rate of application of the resistive ink from which it is formed.
  • inaccuracies in printing and irregularities in the surface of the dielectrically coated substrate can locally affect the width and thickness of the track 3.
  • the resistance of the track 3 will tend to vary from a predetermined value calculated from an ideal length, width and thickness of track.
  • Some methods of applying the dielectric layers to the substrate 2 are better than other in producing a smooth surface on which the track 3 is then printed. However, even with the best methods of production, it is difficult to produce consistently dielectrically coated substrates that can be accurately printed with resistive tracks, which have measured resistances which are always within permitted tolerances.
  • a thick film resistive heating element 1 is additionally printed with at least one compensating thick film resistive track 6.
  • Each track 6 is applied to the surface of the substrate in parallel with the tracks 3A and 3B but electrically disconnected therefrom at the time of application by means of a gap 7. It will be appreciated that the track 6 and the tracks 3A and 3B are all printed at the same time but, as will be described, the gap 7 is thereafter either closed or left open.
  • the electrical resistance of the track 3 comprising the tracks 3A,3B is measured. It can then be determined for each element 1 whether the measured resistance varies from a predetermined ideal value based on the length, width and thickness of the tracks 3 presumed to have been printed by more than a permitted tolerance. As previously mentioned, typically the resistance of such thick film resistive tracks can vary by up to + 15% from a desired level but safety and other standards can require resistive tolerances no more than - 5% and + 10% from a fixed value.
  • the gap 7 can be left open. However, if the measured resistance is found to be higher than the permitted tolerances, the gap 7 can be closed to decrease the overall resistance of the tracks 3.
  • the gap 7 is closed by screen printing a short section of the track 6 with the same thick film ink as used previously for the tracks 3 and 6.
  • one or more compensating tracks 6 could be printed to be connected in series with the tracks 3A,3B to increase the overall resistance of the track 3 when electrically connected thereto, this is unlikely to be practical in most circumstances because the contact portions 4 and 5 require special treatment during production of the element and must usually always be placed in a fixed position for connection to the control device.
  • the track or tracks 6 are normally printed in parallel with the tracks 3A, 3B to reduce their resistance.
  • the expected average resistance of the track 3 based on its ideal thickness, width and length can be arranged to be slightly higher than the required value.
  • the width, length and thickness of each compensating track 6 can be predetermined so that its resistance is on average such that when electrically connected in parallel with the tracks 3A, 3B the measured resistance of the resistive track 3 as a whole will only vary from the required value by an amount no more than the permitted tolerance.
  • At least part of the tracks 3A,3B can be split into a plurality of thinner parallel tracks 8. This spreads the temperature of the tracks 3A and 3B locally and is useful where the element 1 is to be used in conjunction with an electromechanical control device 9. The effect of such track splitting can, however, be taken into account when determining the required resistance of such an element.
  • an encapsulating insulating layer can then applied over the completed circuit and the substrate to protect the circuit.
  • this coating is interrupted in the regions of the contract portions 4 and 5 so that electrical connection can be made thereto.
  • the invention provides a simple means of improving the viability of thick film resistive heating elements by enabling them to meet required standards.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Surface Heating Bodies (AREA)
  • Inorganic Insulating Materials (AREA)
  • Materials For Medical Uses (AREA)
  • Parts Printed On Printed Circuit Boards (AREA)
  • Magnetic Heads (AREA)
  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • Resistance Heating (AREA)
  • Apparatuses And Processes For Manufacturing Resistors (AREA)

Abstract

Ce procédé de fabrication d'une résistance (1) chauffante à couche épaisse comprenant l'application d'une ou de plusieurs pistes (3, 3A, 3B) résistives à couche épaisse sur la surface d'un substrat (2) isolant électriquement, consiste à appliquer au moins une piste (6) résistive compensatrice à couche épaisse sur la surface du substrat (2), lequel, au moment de cette application, est déconnecté électriquement de la ou des pistes (3, 3A, 3B) résistives. Ainsi, lorsque l'on mesure la résistance de la ou de ces pistes (3, 3A, 3B), en excluant la ou les pistes (6) compensatrices, si cette résistance mesurée varie d'une valeur requise prédéterminée supérieure à une plage de tolérance permise, alors on peut connecter électriquement au moins l'une des pistes (6) compensatrices à une ou à plusieurs des pistes (3, 3A, 3B) résistives, afin de porter la résistance totale des pistes (3, 3A, 3B, 6) dans une plage de tolérance permise. De préférence, chaque piste (6) compensatrice à couche épaisse est imprimée en parallèle avec une ou plusieurs des pistes (3, 3A, 3B) résistives, la connexion électrique d'une ou de plusieurs des pistes (6) compensatrices à une ou plusieurs des pistes (3, 3A, 3B) résistives diminuant la résistance, en tant que tout, des pistes (3, 3A, 3B, 6) résistives connectées électriquement.
PCT/GB1995/002751 1994-11-26 1995-11-27 Perfectionnements apportes a des elements a couche epaisse WO1996017496A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE69502630T DE69502630T2 (de) 1994-11-26 1995-11-27 Verbesserungen an dickschichtelementen
EP95937110A EP0793898B1 (fr) 1994-11-26 1995-11-27 Perfectionnements apportes a des elements a couche epaisse
NZ295712A NZ295712A (en) 1994-11-26 1995-11-27 Thick film resistive heating element
AU39315/95A AU694815B2 (en) 1994-11-26 1995-11-27 Improvements to thick film elements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9423901A GB9423901D0 (en) 1994-11-26 1994-11-26 Improvements to thick film elements
GB9423901.9 1994-11-26

Publications (1)

Publication Number Publication Date
WO1996017496A1 true WO1996017496A1 (fr) 1996-06-06

Family

ID=10765022

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/002751 WO1996017496A1 (fr) 1994-11-26 1995-11-27 Perfectionnements apportes a des elements a couche epaisse

Country Status (9)

Country Link
EP (1) EP0793898B1 (fr)
AT (1) ATE166520T1 (fr)
AU (1) AU694815B2 (fr)
CA (1) CA2204601A1 (fr)
DE (1) DE69502630T2 (fr)
ES (1) ES2117452T3 (fr)
GB (1) GB9423901D0 (fr)
NZ (1) NZ295712A (fr)
WO (1) WO1996017496A1 (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997014269A1 (fr) * 1995-10-11 1997-04-17 Strix Limited Dispositifs de chauffage electriques
GB2318544A (en) * 1996-09-19 1998-04-29 John Deveney A carpet seaming iron with improved heatshield and base plate, and a temperature controller for electrical appliances.
WO1999002080A1 (fr) 1997-07-11 1999-01-21 Strix Limited Receptacles chauffant des liquides et dispositifs de reglage adaptes
WO2000030514A1 (fr) 1998-11-26 2000-06-02 Strix Limited Appareil electrique de fabrication de boissons
WO2000067527A1 (fr) * 1999-05-04 2000-11-09 Otter Controls Limited Ameliorations apportees a des elements chauffants, notamment dans le domaine des elements chauffants en couche epaisse
EP1161120A2 (fr) 1997-02-17 2001-12-05 Strix Limited Dispositif de chauffage
WO2005011331A1 (fr) * 2003-07-30 2005-02-03 Koninklijke Philips Electronics N.V. Appareil electromenager et structure de chauffage d'un appareil electromenager
US7041378B2 (en) 2001-04-17 2006-05-09 Koninklijke Philips Electronics N. V. Heating system
WO2009014333A1 (fr) 2007-07-20 2009-01-29 Lg Electronics Inc. Elément chauffant électrique
DE102007056917A1 (de) 2007-11-27 2009-06-04 BSH Bosch und Siemens Hausgeräte GmbH Verfahren zum Fertigungstoleranzausgleich von elektrischen Verbrauchern
EP3614806A1 (fr) * 2018-08-21 2020-02-26 LG Electronics Inc. -1- Chauffage électrique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2153190A (en) * 1984-01-14 1985-08-14 Emi Ltd Improvements in or relating to heaters for water vessels
EP0286217A1 (fr) * 1987-02-25 1988-10-12 THORN EMI plc Bandes en film épais, à résistance électrique
EP0335617A2 (fr) * 1988-03-25 1989-10-04 THORN EMI plc Limitateur de courant pour éléments chauffants à couche épaisse
DE8902013U1 (fr) * 1989-02-21 1990-03-22 Holtkamp, Manfred, 4543 Lienen, De

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2153190A (en) * 1984-01-14 1985-08-14 Emi Ltd Improvements in or relating to heaters for water vessels
EP0286217A1 (fr) * 1987-02-25 1988-10-12 THORN EMI plc Bandes en film épais, à résistance électrique
EP0335617A2 (fr) * 1988-03-25 1989-10-04 THORN EMI plc Limitateur de courant pour éléments chauffants à couche épaisse
DE8902013U1 (fr) * 1989-02-21 1990-03-22 Holtkamp, Manfred, 4543 Lienen, De

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2321579B (en) * 1995-10-11 2000-07-26 Strix Ltd Electric heaters
GB2321579A (en) * 1995-10-11 1998-07-29 Strix Ltd Electric heaters
WO1997014269A1 (fr) * 1995-10-11 1997-04-17 Strix Limited Dispositifs de chauffage electriques
GB2318544A (en) * 1996-09-19 1998-04-29 John Deveney A carpet seaming iron with improved heatshield and base plate, and a temperature controller for electrical appliances.
EP1161120A2 (fr) 1997-02-17 2001-12-05 Strix Limited Dispositif de chauffage
CN1327745C (zh) * 1997-07-11 2007-07-18 斯特里克斯有限公司 厚膜加热器和液体加热装置
WO1999002080A1 (fr) 1997-07-11 1999-01-21 Strix Limited Receptacles chauffant des liquides et dispositifs de reglage adaptes
WO2000030514A1 (fr) 1998-11-26 2000-06-02 Strix Limited Appareil electrique de fabrication de boissons
WO2000067527A1 (fr) * 1999-05-04 2000-11-09 Otter Controls Limited Ameliorations apportees a des elements chauffants, notamment dans le domaine des elements chauffants en couche epaisse
US7041378B2 (en) 2001-04-17 2006-05-09 Koninklijke Philips Electronics N. V. Heating system
WO2005011331A1 (fr) * 2003-07-30 2005-02-03 Koninklijke Philips Electronics N.V. Appareil electromenager et structure de chauffage d'un appareil electromenager
EP2186380A1 (fr) * 2007-07-20 2010-05-19 Lg Electronics Inc. Elément chauffant électrique
WO2009014333A1 (fr) 2007-07-20 2009-01-29 Lg Electronics Inc. Elément chauffant électrique
EP2186380A4 (fr) * 2007-07-20 2012-05-09 Lg Electronics Inc Elément chauffant électrique
US8269150B2 (en) 2007-07-20 2012-09-18 Lg Electronics Inc. Electric heater
EP2186380B1 (fr) 2007-07-20 2016-06-22 LG Electronics Inc. Elément chauffant électrique
DE102007056917A1 (de) 2007-11-27 2009-06-04 BSH Bosch und Siemens Hausgeräte GmbH Verfahren zum Fertigungstoleranzausgleich von elektrischen Verbrauchern
WO2009068389A2 (fr) * 2007-11-27 2009-06-04 BSH Bosch und Siemens Hausgeräte GmbH Procédé pour compenser les tolérances de fabrication de consommateurs électriques
WO2009068389A3 (fr) * 2007-11-27 2009-08-06 Bsh Bosch Siemens Hausgeraete Procédé pour compenser les tolérances de fabrication de consommateurs électriques
EP3614806A1 (fr) * 2018-08-21 2020-02-26 LG Electronics Inc. -1- Chauffage électrique
US11435088B2 (en) 2018-08-21 2022-09-06 Lg Electronics Inc. Electric heater and cooking appliance having same

Also Published As

Publication number Publication date
GB9423901D0 (en) 1995-01-11
NZ295712A (en) 1998-08-26
DE69502630T2 (de) 1999-02-11
AU694815B2 (en) 1998-07-30
ATE166520T1 (de) 1998-06-15
DE69502630D1 (de) 1998-06-25
EP0793898B1 (fr) 1998-05-20
EP0793898A1 (fr) 1997-09-10
AU3931595A (en) 1996-06-19
ES2117452T3 (es) 1998-08-01
CA2204601A1 (fr) 1996-06-06

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