EP0308306A1 - PTC-Thermistor für Oberflächenbestückung - Google Patents

PTC-Thermistor für Oberflächenbestückung Download PDF

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Publication number
EP0308306A1
EP0308306A1 EP88402281A EP88402281A EP0308306A1 EP 0308306 A1 EP0308306 A1 EP 0308306A1 EP 88402281 A EP88402281 A EP 88402281A EP 88402281 A EP88402281 A EP 88402281A EP 0308306 A1 EP0308306 A1 EP 0308306A1
Authority
EP
European Patent Office
Prior art keywords
thermistor according
conductive coating
electrical
ceramic element
ceramic
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP88402281A
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English (en)
French (fr)
Inventor
Françoise Mallez
Alain Lagrange
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Compagnie Europeenne de Composants Electroniques LCC CICE
Original Assignee
Compagnie Europeenne de Composants Electroniques LCC CICE
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 Compagnie Europeenne de Composants Electroniques LCC CICE filed Critical Compagnie Europeenne de Composants Electroniques LCC CICE
Publication of EP0308306A1 publication Critical patent/EP0308306A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/1406—Terminals or electrodes formed on resistive elements having positive temperature coefficient
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/006—Apparatus or processes specially adapted for manufacturing resistors adapted for manufacturing resistor chips

Definitions

  • the invention relates to thermistors with a positive temperature coefficient or PTC and which can be mounted on the surface.
  • the basic products used are essentially perovskite ceramics (alkaline earth titanates) which have been made conductive by valence induction (doping with 3+ or 5+ ions).
  • the CTP effect results from the combination of three causes: a polycrystalline microstructure, a semiconductor material and the ferroelectric / paraelectric phase change. It is due to the formation of electrical potential barriers at the grain boundaries.
  • the overall result is a sharp and abrupt increase in resistivity when passing the Curie point.
  • a thermistor with a positive coefficient hence sometimes the name of posistance.
  • the positive temperature coefficient domain is located just above the Curie point. Its width is of the order of a few tens of degrees and it is all the more narrower the higher the temperature coefficient.
  • the Siemens Company has marketed PTC thermistors consisting of a metallized parallelepiped at its ends. Each electrical termination has two layers: a layer of an alloy of silver, indium and gallium to have good ohmic contact with the ceramic and, this layer being difficult to weld, a layer of silver to provide a surface having good weldability (silver alone providing poor ohmic contact).
  • the disadvantage of these products is that they do not hold up to wettability tests and dewetting tests.
  • the present invention provides PTC thermistors as a component for surface mounting, each electrical termination of which comprises a metallization intended to ensure ohmic contact on the ceramic and a connection or a cover fixed on the metallization and allowing the soldering of the component on a circuit.
  • the invention therefore relates to a thermistor with a positive temperature coefficient for surface mounting, consisting of a ceramic element and two electrical terminations, characterized in that each electrical termination is formed of a conductive coating deposited directly on ceramic and providing good ohmic contact, and a weldable electrical connection attached to the ceramic element and ensuring good electrical contact with the conductive coating.
  • the components for surface mounting can be, in their most basic structure, in two forms: in the form of a parallelepiped supporting metallizations at the ends (chip) or in the form of a rod or a tube supporting weldable metallizations at the ends (melf).
  • FIG. 1 represents a chip comprising a parallelepiped 1 and two metallizations 2 and 3 at its ends.
  • FIG. 2 represents a melf comprising a stick 4 and two metallizations 5 and 6 at its ends.
  • the invention proposes to deposit an ohmic layer, at the places reserved for the terminations to obtain a chip or a melf, then to fix electrical connections or covers on these terminations.
  • FIG. 3 represents a PTC thermistor according to the invention, consisting of a parallelepiped 10 the ends of which are covered with conductive coatings 11 and 12. On these conductive coatings covers 13 and 14 have been fixed. The covers 13 and 14 are weldable and they must ensure good electrical contact with this coating. In Figure 3, they have been given a U-shaped section but other shapes are suitable. One can for example use covers which cover all the metallized sides.
  • the conductive coatings can consist of metallizations deposited by dipping from an ink ensuring good ohmic contact. It is thus possible to deposit a layer of aluminum or of an alloy of silver, indium and gallium, for example. This dip metallization method provides good returns. Metallizations can also be deposited by spraying processes.
  • FIG. 4 represents, in profile view, a detail of PTC thermistor according to the invention.
  • a cover is engaged by pressure which is a clip 22, for example made of nickel-plated and tinned iron.
  • Contact can be made directly on the metallization or else by means of a soldering cream 23 deposited at the bottom of the clip before its engagement.
  • the soldering cream must have a higher melting temperature than that of the solder which will be used for transfer to the printed circuit.
  • FIG. 5 represents, in profile view, a detail of another PTC thermistor according to the invention.
  • a cover 32 of the type shown in FIG. 3 has been engaged.
  • This cover may be made of iron nickel-plated and tinned.
  • the contact can be made by means of a soldering cream 33 deposited at the bottom of the cover before its engagement.
  • the soldering cream must have a higher melting temperature than that of the solder which will be used for transfer to the printed circuit.
  • hoods simple hoods or clips
  • cylindrical rods of Figure 2 can be attached to the same types of hoods (simple hoods or clips) to the cylindrical rods of Figure 2, taking into account of course their geometry.
  • FIG. 6 is a sectional view of a PTC thermistor according to the invention and formed from a ceramic tube 40.
  • the internal and external metallizations are carried out with an aluminum ink.
  • a brush is used for internal metallization.
  • the value of the thermistor can be adjusted by machining a metallization (sandblast, laser beam, etc.).
  • a first conductive coating 41 is thus obtained which covers almost the entire interior of the tube, emerges from one end of the tube and covers a small outer annular portion as shown in FIG. 6.
  • a second conductive coating 42 which also covers most of the outer cylindrical surface of the tube and one of its ends.
  • Hoods 43 and 44 can then be placed at each end using soldering cream.
  • the hoods that can be used can also be circular clips or rings. They are advantageously made of nickel-plated and tinned iron.
  • the tube makes it possible to obtain thermistors with a low ohmic value.
  • FIG. 7 is a side view of a PTC thermistor according to the invention.
  • the largest faces of the parallelepiped 50 are covered with metallizations 51 and 52 which allow alternating margins to remain.
  • the metallizations are for example made of aluminum and obtained by screen printing.
  • the screen printing can relate to a relatively large ceramic plate which will then be cut to obtain individual elements such as that defined by the parallelepiped 50.
  • the layers 53 and 54 are for example silver layers deposited by dipping. Their role is to ensure good electrical contact with the covers 55 and 56 which are fixed at the ends and which can be clips made of nickel-plated and tinned iron. You can also use solder cream to fix the covers.
  • a PTC thermistor it is also part of the invention to mount a PTC thermistor in a box.
  • the thermistor being formed from a parallelepiped or a disc supporting two metallizations obtained for example by aluminum screen printing. It is then possible, using a connection strip such as that described in patent application FR 2 581 827, to manufacture components for surface mounting in series.
  • the housing then consists of a block of molded resin. Electrical connections, welded (for example by laser welding) on the metal coatings of the elements, emerge from the resin block and are pressed against it as taught by the cited patent application. When soldering the component on its circuit of use, the resin will protect the ceramic from the heat of the solder bath.
  • the components according to the invention have the advantage of withstanding wettability tests and satisfying dewetting tests.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Thermistors And Varistors (AREA)
EP88402281A 1987-09-15 1988-09-09 PTC-Thermistor für Oberflächenbestückung Withdrawn EP0308306A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8712776 1987-09-15
FR8712776A FR2620561B1 (fr) 1987-09-15 1987-09-15 Thermistance ctp pour le montage en surface

Publications (1)

Publication Number Publication Date
EP0308306A1 true EP0308306A1 (de) 1989-03-22

Family

ID=9354919

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88402281A Withdrawn EP0308306A1 (de) 1987-09-15 1988-09-09 PTC-Thermistor für Oberflächenbestückung

Country Status (2)

Country Link
EP (1) EP0308306A1 (de)
FR (1) FR2620561B1 (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2222311A (en) * 1988-08-26 1990-02-28 Dale Electronics Resistor with terminal pads for surface mounting
EP0429633A1 (de) * 1989-06-19 1991-06-05 Dale Electronics Thermistor und dessen herstellung.
EP0522863A1 (de) * 1991-07-12 1993-01-13 Daito Communication Apparatus Co. Ltd. Anordnung mit positivem Temperaturkoeffizient
WO1994001876A1 (en) * 1992-07-09 1994-01-20 Raychem Corporation Electrical devices
GB2265761B (en) * 1992-03-30 1996-07-17 Dale Electronics Bulk metal chip resistor
US5852397A (en) * 1992-07-09 1998-12-22 Raychem Corporation Electrical devices
US5952911A (en) * 1996-10-09 1999-09-14 Murata Manufacturing Co., Ltd. Thermistor chips and methods of making same
US6081181A (en) * 1996-10-09 2000-06-27 Murata Manufacturing Co., Ltd. Thermistor chips and methods of making same
US6292088B1 (en) 1994-05-16 2001-09-18 Tyco Electronics Corporation PTC electrical devices for installation on printed circuit boards
US6640420B1 (en) 1999-09-14 2003-11-04 Tyco Electronics Corporation Process for manufacturing a composite polymeric circuit protection device
US20100090332A1 (en) * 2008-10-09 2010-04-15 Joinset Co., Ltd. Ceramic chip assembly

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3996447A (en) * 1974-11-29 1976-12-07 Texas Instruments Incorporated PTC resistance heater
DE2816593A1 (de) * 1978-04-17 1979-10-18 Siemens Ag Elektrisches widerstandsbauelement, das aus einem hohlzylinderfoermigen keramischen kaltleiterkoerper besteht
GB2146488A (en) * 1983-09-09 1985-04-17 Tdk Corp A ptc resistor device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3996447A (en) * 1974-11-29 1976-12-07 Texas Instruments Incorporated PTC resistance heater
DE2816593A1 (de) * 1978-04-17 1979-10-18 Siemens Ag Elektrisches widerstandsbauelement, das aus einem hohlzylinderfoermigen keramischen kaltleiterkoerper besteht
GB2146488A (en) * 1983-09-09 1985-04-17 Tdk Corp A ptc resistor device

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2222311B (en) * 1988-08-26 1993-04-28 Dale Electronics Surface mount wirewound resistor and method of making the same
GB2222311A (en) * 1988-08-26 1990-02-28 Dale Electronics Resistor with terminal pads for surface mounting
EP0429633A1 (de) * 1989-06-19 1991-06-05 Dale Electronics Thermistor und dessen herstellung.
EP0429633A4 (en) * 1989-06-19 1992-12-23 Dale Electronics, Inc. Thermistor and method of making the same
EP0522863A1 (de) * 1991-07-12 1993-01-13 Daito Communication Apparatus Co. Ltd. Anordnung mit positivem Temperaturkoeffizient
GB2265761B (en) * 1992-03-30 1996-07-17 Dale Electronics Bulk metal chip resistor
DE4310288B4 (de) * 1992-03-30 2005-11-10 Vishay Dale Electronics, Inc. (n.d.Ges.d. Staates Delaware), Columbus Oberflächenmontierbarer Widerstand
US6651315B1 (en) 1992-07-09 2003-11-25 Tyco Electronics Corporation Electrical devices
WO1994001876A1 (en) * 1992-07-09 1994-01-20 Raychem Corporation Electrical devices
US5852397A (en) * 1992-07-09 1998-12-22 Raychem Corporation Electrical devices
US7355504B2 (en) 1992-07-09 2008-04-08 Tyco Electronics Corporation Electrical devices
US6292088B1 (en) 1994-05-16 2001-09-18 Tyco Electronics Corporation PTC electrical devices for installation on printed circuit boards
US5952911A (en) * 1996-10-09 1999-09-14 Murata Manufacturing Co., Ltd. Thermistor chips and methods of making same
US6100110A (en) * 1996-10-09 2000-08-08 Murata Manufacturing Co., Ltd. Methods of making thermistor chips
US6081181A (en) * 1996-10-09 2000-06-27 Murata Manufacturing Co., Ltd. Thermistor chips and methods of making same
US6640420B1 (en) 1999-09-14 2003-11-04 Tyco Electronics Corporation Process for manufacturing a composite polymeric circuit protection device
US20100090332A1 (en) * 2008-10-09 2010-04-15 Joinset Co., Ltd. Ceramic chip assembly

Also Published As

Publication number Publication date
FR2620561A1 (fr) 1989-03-17
FR2620561B1 (fr) 1992-04-24

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