WO1998036617A1 - Thick film heaters - Google Patents
Thick film heaters Download PDFInfo
- Publication number
- WO1998036617A1 WO1998036617A1 PCT/GB1998/000487 GB9800487W WO9836617A1 WO 1998036617 A1 WO1998036617 A1 WO 1998036617A1 GB 9800487 W GB9800487 W GB 9800487W WO 9836617 A1 WO9836617 A1 WO 9836617A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- contact member
- contact
- heater
- track
- thick film
- Prior art date
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
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0202—Switches
- H05B1/0213—Switches using bimetallic 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
- 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
- H05B3/262—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 insulated metal plate
-
- 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
- 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
- H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
-
- 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
- H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
- H05B3/283—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material the insulating material being an inorganic material, e.g. ceramic
-
- 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
- H05B3/78—Heating arrangements specially adapted for immersion heating
- H05B3/82—Fixedly-mounted immersion 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
- H05B2203/013—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
Definitions
- the present invention relates to thick film heaters which can be used particularly, but not exclusively, in liquid heating apparatus such as kettles, hot water jugs and so on.
- a thick film heater comprises a so-called 'thick film' resistive heating track printed and fired onto an electrically insulating substrate.
- a so-called 'thick film' resistive heating track printed and fired onto an electrically insulating substrate.
- an insulating glass ceramic ink are deposited onto a metallic support and fired to form an insulating layer on the support.
- An electrically resistive ink is then printed onto the insulating layer in a desired track pattern and fired to produce the heating track.
- the track may then be overprinted with a protective glass ceramic glaze which is also fired.
- the heating track is also provided with terminals through which electrical connection to the track is made. This connection can be made in a number of ways. For example in one proposal a connecting electrical lead is soldered onto the track and using an appropriate solder. However such a connection is vulnerable to being pulled off.
- the track is provided with printed silver contact pads .
- these pads are formed by printing over the end portions of the track with a suitable ink which is then fired.
- a connection is made to the track, for example with a formed leaf spring, as shown in GB 2283156, or by a sprung knife edge contact .
- the problem with such a contact is, however, that contact is only made along a line which means that overheating of the contact may well occur.
- the pad is very thin (typically 10-15 ⁇ m) it will not last very long.
- the invention provides a thick film heater comprising a thick film heating track provided on an electrically insulating substrate, and having an electrical contact member bonded to the heater.
- the invention also extends to a method of making a thick film heater comprising a thick film heating track provided on an electrically insulating substrate wherein a contact member is bonded to the heater.
- a separate contact member is bonded to the heater to provide a contact which may better withstand wear and high temperatures particularly where the contact is one of a set of switch contacts. Furthermore, it will enable a more acceptable electrical contact to be made even with a non-movable connection such as a leaf spring.
- the bonded contact will also provide a larger interface area with an underlying track, reducing heating at the interface, thereby prolonging contact life.
- the contact member may be bonded to the heater using an electrically conductive bonding material, for example a solder or braze material, which will be capable of withstanding the anticipated operating temperatures of the heater. This could be done during a firing operation during manufacture of the heater. However, it has been found that an extremely strong bond can be achieved if the contact member is merely positioned on an area of unfired material on the heater and then fired with it to bond the contact member to the resultant fired material.
- an electrically conductive bonding material for example a solder or braze material
- the contact member may be positioned onto an unfired section of the track itself but more preferably it is positioned onto a contact receiving pad of high conductivity material, such as that presently used to produce contact pads, which is in electrical connection with the track.
- the contact member is positioned on the contact receiving pad such that it overlies a portion of the track.
- the contact receiving pad may be elongate, and the contact member positioned at an end thereof remote from the track.
- the present invention also provides a method of mounting a contact member on a thick film heater wherein the contact member is positioned in a desired position on an area of unfired material and the unfired material and contact member are fired together to secure the contact member in position.
- the various unfired materials referred to above will normally be layers of ink printed onto the heater in an appropriate pattern.
- the unfired material ink may be printed thicker under the contact member, or additional ink deposited in an appropriate manner prior to positioning the contact member.
- the contact member is preferably deposited onto an ink layer whilst the ink is still wet. It may be pressed into the ink and possibly also be vibrated at the same time. Positioning the contact member on wet ink not only acts to wet the bottom of the contact member, thereby improving adhesion, but also acts to some extent positively to locate the contact member on the heater, which is beneficial during subsequent processing where the contact member may be subject to external forces, eg. vibration, as it passes through a firing furnace.
- the firing of the contact member onto the heater may be conducted as a separate operation, but most preferably it is carried out at the same time as another firing operation in the heater manufacture.
- the heater track, the contact receiving pad, and possibly an overglaze layer may all be printed on a fired, or unfired insulating substrate. After all the printing operations have been completed, the contact member is positioned on the intermediate contact layer, and the whole assembly then fired.
- the contact member may be made of conventional contact materials. Where, as is preferred, the contact member is intended to form one of a set of switch contacts, the contact forming face of the contact may advantageously be made from Ag/CdO, Ag/Ni or more preferably pure silver which gives very low contact interface resistance. This minimises heating in the contact region, which keeps the temperature of the track and insulating materials below the contact to a minimum.
- the contact member may also be formed as a composite contact having a facing as discussed above with a suitable backing material .
- the backing material is a ferrous alloy, for example comprising Nickel and/or Chromium, rather than the more common Cu/Ni backing material. Ferrous alloys are preferred as they exhibit improved oxidation resistance during firing.
- the contact member may be cut from a wire or tape of contact material. Further the heater-facing side of the contact may be roughened, for example by forming annular or cross hatch patterns, to as to improve the adherence of the contact member. Alternatively or in addition, the edges of the contact member may be roughened, for example with serrations to improve keying into the underlying material.
- Figure 2 shows, schematically, a section along line II-II of Fig. 1 ;
- Figure 3 shows schematically production of contact members
- Figure 4 shows a further embodiment of the invention.
- a tortuous thick film heating track 8 about 15 ⁇ m thick.
- a protective overglaze 10 about 15 ⁇ m thick (Figure 2) is provided over substantially the whole surface of plate 4. However, apertures 12 are provided around three contact locations 14 on the tracks, so that electrical connections can be made to the track 8 at those locations.
- a silver contact member 16 about 0.5 mm thick is bonded to the track 8 via a silver contact receiving pad 18.
- Each contact member 16 is generally square in section, being cut e.g. stamped, from the end of a tape 20, as shown in Figure 3.
- the cut is a serrated one, whereby opposed serrated edges 22 are provided on the contact member 16. This will improve its bonding to the track in that during firing, as .will be described below, material will be drawn up into the serrations.
- a layer 6 of insulating ink such as Dupont 3500 is printed onto the plate 4, in a single or multiple operation, to a depth of about 150-200 ⁇ m. This layer 6 may then be fired at about 850°C for about 30 minutes to produce the finished insulating layer 6.
- the resistive heating track 8 of a material such as a mixture of Dupont 3542 and 3544 is printed to a thickness of about 15-20 ⁇ m.
- contact receiving pads 18 of Dupont 7760 are printed in the appropriate positions to a thickness of about 15-20 ⁇ m, and finally an overglaze 10 of Dupont 3500 printed to a thickness of about 15-20 ⁇ m over the whole of the insulating layer 6, apart from the areas around the contact locations 14.
- the contact receiving pads 18 are still wet the contact members 16 are positioned on the pads 18.
- the contact members 16 are pressed into the pads 18 to ensure good contact, and may even be vibrated into a position to eliminate gas bubbles etc. under the contact member 16.
- the heater 2 may then be fired at about 850°C for about 30 minutes both to fire the track 8, contact receiving pads 18 and overglaze 10 and to bond the contact members 16 in position.
- the contact receiving pads 18 will initially soften and, if they have not done so already, fill interstices in the lower surface of the contact members by capillarity. The material will also be drawn up around the edges of the contact member 16 into the serrations therein. After further time, the pad material will harden to firmly secure the contact members in position. It has been found, perhaps surprisingly, that the firing process does not oxidise the contact member 16.
- Various modifications to the above embodiment may be made without departing from the scope of the invention.
- the contact member 16 need not directly overlie the track 8.
- the silver contact pad 18 is extended away from the end of the track 8 and the contact member 16 mounted at the end 24 of the pad remote from the track end. The elongated contact pad 18 acts to secure the contact member 16 and connect it electrically to the track 8.
- contact member 16 need not be square and can take whatever shape is desired, for example, circular, but a square or rectangular contact member offers advantages in manufacture, as discussed above.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Contacts (AREA)
- Surface Heating Bodies (AREA)
- Resistance Heating (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU62242/98A AU6224298A (en) | 1997-02-17 | 1998-02-17 | Thick film heaters |
EP98904300A EP1013147A1 (en) | 1997-02-17 | 1998-02-17 | Thick film heaters |
GB9919457A GB2337682A (en) | 1997-02-17 | 1998-02-17 | Thick film heaters |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9703224.7 | 1997-02-17 | ||
GB9703224A GB2322272A (en) | 1997-02-17 | 1997-02-17 | Terminal arrangement for a thick film heater |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998036617A1 true WO1998036617A1 (en) | 1998-08-20 |
Family
ID=10807777
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1998/000487 WO1998036617A1 (en) | 1997-02-17 | 1998-02-17 | Thick film heaters |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1013147A1 (en) |
CN (2) | CN1252921A (en) |
AU (1) | AU6224298A (en) |
GB (1) | GB2322272A (en) |
WO (1) | WO1998036617A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002071806A1 (en) * | 2001-03-06 | 2002-09-12 | Schott Glas | Ceramic hotplate consisting of a glass ceramic plate |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6817088B1 (en) * | 2000-06-16 | 2004-11-16 | Watlow Electric Msg.C | Termination method for thick film resistance heater |
GB0217351D0 (en) | 2002-07-25 | 2002-09-04 | Ceramaspeed Ltd | Radiant electric heater |
CN101500347B (en) * | 2009-03-03 | 2012-10-31 | 深圳市格普斯纳米电热科技有限公司 | Electricity connection method for electric heating film |
DE102014202302B4 (en) * | 2013-07-03 | 2015-02-19 | Technische Universität Dresden | Device for heating preforms |
KR102110417B1 (en) * | 2018-08-21 | 2020-05-13 | 엘지전자 주식회사 | Electric Heater |
KR102048733B1 (en) * | 2018-08-21 | 2019-11-27 | 엘지전자 주식회사 | Electric Heater |
KR102111332B1 (en) | 2018-10-11 | 2020-05-15 | 엘지전자 주식회사 | Electric Heater |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4247981A (en) * | 1979-06-18 | 1981-02-03 | Western Electric Company, Inc. | Methods of assembling interconnect members with printed circuit boards |
DE3833293A1 (en) * | 1987-10-01 | 1989-04-20 | Interconnection B V | Heating element |
EP0329421A2 (en) * | 1988-02-16 | 1989-08-23 | THORN EMI plc | Heating unit |
WO1994003027A1 (en) * | 1992-07-22 | 1994-02-03 | Central Research Laboratories Limited | Electrical connection to thick film tracks |
WO1996017405A1 (en) * | 1994-11-26 | 1996-06-06 | Phet Ireland Limited | Electrical connection method |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB737058A (en) * | 1952-09-02 | 1955-09-21 | Wmf Wuerttemberg Metallwaren | Method of manufacturing heating conductors for electric heating apparatus |
GB1112473A (en) * | 1965-09-04 | 1968-05-08 | Fuji Photo Film Co Ltd | Improvements in and relating to the connection of leading wires to electrodes on surface electro-conductive elements |
GB8905014D0 (en) * | 1989-03-04 | 1989-04-19 | Emi Plc Thorn | Electrical connectors |
-
1997
- 1997-02-17 GB GB9703224A patent/GB2322272A/en not_active Withdrawn
-
1998
- 1998-02-17 WO PCT/GB1998/000487 patent/WO1998036617A1/en not_active Application Discontinuation
- 1998-02-17 EP EP98904300A patent/EP1013147A1/en not_active Withdrawn
- 1998-02-17 CN CN 98804187 patent/CN1252921A/en active Pending
- 1998-02-17 CN CN98208708U patent/CN2388794Y/en not_active Expired - Fee Related
- 1998-02-17 AU AU62242/98A patent/AU6224298A/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4247981A (en) * | 1979-06-18 | 1981-02-03 | Western Electric Company, Inc. | Methods of assembling interconnect members with printed circuit boards |
DE3833293A1 (en) * | 1987-10-01 | 1989-04-20 | Interconnection B V | Heating element |
EP0329421A2 (en) * | 1988-02-16 | 1989-08-23 | THORN EMI plc | Heating unit |
WO1994003027A1 (en) * | 1992-07-22 | 1994-02-03 | Central Research Laboratories Limited | Electrical connection to thick film tracks |
WO1996017405A1 (en) * | 1994-11-26 | 1996-06-06 | Phet Ireland Limited | Electrical connection method |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002071806A1 (en) * | 2001-03-06 | 2002-09-12 | Schott Glas | Ceramic hotplate consisting of a glass ceramic plate |
Also Published As
Publication number | Publication date |
---|---|
GB2322272A (en) | 1998-08-19 |
CN1252921A (en) | 2000-05-10 |
EP1013147A1 (en) | 2000-06-28 |
CN2388794Y (en) | 2000-07-19 |
GB9703224D0 (en) | 1997-04-09 |
AU6224298A (en) | 1998-09-08 |
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