EP0129997B1 - Process for the production of ptc thermistors - Google Patents

Process for the production of ptc thermistors Download PDF

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Publication number
EP0129997B1
EP0129997B1 EP84303796A EP84303796A EP0129997B1 EP 0129997 B1 EP0129997 B1 EP 0129997B1 EP 84303796 A EP84303796 A EP 84303796A EP 84303796 A EP84303796 A EP 84303796A EP 0129997 B1 EP0129997 B1 EP 0129997B1
Authority
EP
European Patent Office
Prior art keywords
pbo
glass
process according
sealing
sio
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.)
Expired
Application number
EP84303796A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0129997A1 (en
Inventor
Keiichi Minegishi
Tokuji Akiba
Tadao Katoh
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.)
Taiheiyo Cement Corp
Original Assignee
Chichibu Cement Co Ltd
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 Chichibu Cement Co Ltd filed Critical Chichibu Cement Co Ltd
Publication of EP0129997A1 publication Critical patent/EP0129997A1/en
Application granted granted Critical
Publication of EP0129997B1 publication Critical patent/EP0129997B1/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/02—Apparatus or processes specially adapted for manufacturing resistors adapted for manufacturing resistors with envelope or housing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
    • H01C1/024—Housing; Enclosing; Embedding; Filling the housing or enclosure the housing or enclosure being hermetically sealed
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H01C7/022—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient mainly consisting of non-metallic substances
    • H01C7/023—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient mainly consisting of non-metallic substances containing oxides or oxidic compounds, e.g. ferrites
    • H01C7/025—Perovskites, e.g. titanates

Definitions

  • the present invention relates to a process for the production of PTC thermistors.
  • a thermistor aimed at sensing temperature alone includes a thermistor element sealed in glass or resin so as to keep it from being affected by other factors such as humidity or gas.
  • NTC thermistors there are available glass-sealed type thermistors which are inexpensive, easy to mass-produce and have stabilized properties, in addition to resin-sealed type disc-form thermistors.
  • PTC thermistors use is made of resin-sealed disc-form PTC thermistors or PTC thermistors in which metals are mechanically pressed onto electrodes.
  • U.S. Patent 3,377,561 discloses a process for the production of PTC thermistors comprising the step of sealing a positive temperature coefficient semiconductor ceramic material in glass in the presence of air.
  • a main object of the present invention is to provide inexpensive glass-sealed type PTC thermistors which show a great change in resistance, especially a markedly increased change in resistance at switching temperatures, and which have stabilized properties.
  • a process for the production of PTC thermistors by sealing a positive temperature coefficient semiconductor ceramic material in low-melting glass having a softening point of no higher than 560°C in the presence of air, oxygen or an air/oxygen mixture containing higher than 0% to lower than 100% volume of air.
  • the semiconductor ceramic material having a positive temperature coefficient used in the present invention there are mentioned those obtained by adding to barium titanate base compositions any one of trivalent antimony, trivalent bismuth, pentavalent tantalum, pentavalent niobium or a rare earth metal.
  • the glass used has a softening point of 450°C-560°C inclusive, and includes those glasses based on B 2 0 3 -PbO-ZnO, B 2 0 3 -PbO-SiO 2 , B 2 0 3 -PbO-TiO 2 , B 2 0 3 -Pb0-Si0 2 -AI 2 0 3 -ZnO, B 2 0 3 -Pb0-V 2 0 5 , S!0 2 -PbO-K 2 0, Si0 2 -PbO-Na 2 O and SiO 2 -PbO-K 2 0-Na 2 O, Preference is given to a Si0 2 -PbO-K 2 0 base glass, since this glass shows desirous thermal expansion and wettability with respect to lead wires (Dumet wires, viz., Fe-Ni alloy wires plated with Cu).
  • a semiconductor barium titanate ceramic material 1 is first sliced to any suitable thickness having regard to the length of a glass tube 4 in which the finished thermistor element is to be sealed.
  • Silver electrodes 2 and 2 are applied to both sides of the thus obtained element, and deposited thereto for 20 minutes at 600°C.
  • Figure 1(a) shows a section of the electrode-provided element.
  • the element is then cut to any length corresponding to the diameter of the glass tube 4.
  • the element is placed in the tube 4 of a glass having a softening point of no higher than 560°C, into both ends of which Dumet wires 3 and 3 are inserted. Finally, the glass tube 4 is sealed by means of a carbon heater jig.
  • the sealing temperature is determined depending upon the softening point of the glass used, and is generally higher than the softening point of the glass used by 50°C or more.
  • NTC glass sealed thermistors a glass having a softening point exceeding 560°C is used and sealing is carried out at a temperature exceeding 610°C. If sealing of a PTC thermistor is carried out under such conditions, there is a marked drop in the properties of the resulting PTC thermistor. According to the present invention, however, it is possible to obtain stable PTC thermistors whose properties drop only slightly by sealing the thermistor elements in a low-melting glass having a softening point of no higher than 560°C.
  • Figure 2 shows the results of an experiment run wherein PTC thermistor elements having a Curie point of 120°C were sealed in glasses in the art.
  • Figure 3 is a characteristic diagram of a PTC thermistor sealed in glass in various atmospheres.
  • the PTC thermistor used had a Curie point of 120°C, and sealing was carried out at 610°C.
  • Figure 4 is a graphical view showing the relation between the specific resistance and the temperature of PTC thermistors obtained by sealing a PTC thermistor element having a Curie point of 120°C in glass in air and/or oxygen gas. The results of Figure 4 are numerically given in Table 3.
  • the present invention makes it possible to inexpensively prepare PTC thermistors having excellent properties, and is therefore of industrially high value.

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Ceramic Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Thermistors And Varistors (AREA)
  • Ceramic Products (AREA)
  • Glass Compositions (AREA)
EP84303796A 1983-06-11 1984-06-05 Process for the production of ptc thermistors Expired EP0129997B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP104483/83 1983-06-11
JP58104483A JPS59229803A (ja) 1983-06-11 1983-06-11 Ｐｔｃ　サ−ミスタの製造法

Publications (2)

Publication Number Publication Date
EP0129997A1 EP0129997A1 (en) 1985-01-02
EP0129997B1 true EP0129997B1 (en) 1988-08-31

Family

ID=14381803

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84303796A Expired EP0129997B1 (en) 1983-06-11 1984-06-05 Process for the production of ptc thermistors

Country Status (4)

Country Link
EP (1) EP0129997B1 (enrdf_load_stackoverflow)
JP (1) JPS59229803A (enrdf_load_stackoverflow)
KR (1) KR900005267B1 (enrdf_load_stackoverflow)
DE (1) DE3473801D1 (enrdf_load_stackoverflow)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62190302U (enrdf_load_stackoverflow) * 1986-05-23 1987-12-03
EP0443618B1 (en) * 1990-02-22 1995-11-08 Murata Manufacturing Co., Ltd. Method for producing a PTC thermistor
JPH1055903A (ja) * 1996-08-09 1998-02-24 Mitsubishi Materials Corp 電子部品の構造

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL287531A (enrdf_load_stackoverflow) * 1962-08-11
US3377561A (en) * 1965-07-13 1968-04-09 Bell Telephone Labor Inc Positive temperature coefficient titanate thermistor
LU69220A1 (enrdf_load_stackoverflow) * 1973-06-18 1974-04-08
US4276536A (en) * 1979-09-04 1981-06-30 Scully Electronic Systems, Inc. Self-heating thermistor probe for low temperature applications

Also Published As

Publication number Publication date
EP0129997A1 (en) 1985-01-02
KR850000811A (ko) 1985-03-09
DE3473801D1 (en) 1988-10-06
JPS59229803A (ja) 1984-12-24
JPH0145962B2 (enrdf_load_stackoverflow) 1989-10-05
KR900005267B1 (ko) 1990-07-21

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