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
  • H01C7/027—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 consisting of conducting or semi-conducting material dispersed in a non-conductive organic 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
  • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
  • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
  • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
  • H05B3/146—Conductive polymers, e.g. polyethylene, thermoplastics
• • 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
  • 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
  • H05B2203/02—Heaters using heating elements having a positive temperature coefficient

Definitions

• the present invention relates to an electrical device having a positive temperature coefficient (PTC) conductive polymer, and more particularly to an electrical device having PTC conductive polymer, which is made by combining electrodes in which electroless nickel plating is formed on an electrolytic copper foil, with PTC conductive polymer, so ensuring improved PTC characteristics and good chemical and mechanical binding capacity between the electrodes and the PTC conductive polymer.
• PTC positive temperature coefficient
• the conductive polymer shows PTC characteristics that conductive fillers are dispersed on organic polymer.
• PTC means a characteristic that electrical resistance rapidly increases at a relatively narrow temperature range due to increase of temperature.
• High molecular substances having PTC characteristics are generally used in a constant- temperature wire, a protection device for blocking over current, a circuit protection element, a heater and so on.
• Such conductive polymer is mechanically chemically combined with at least one electrode in an electrical device.
• a metal plate is generally used as the electrode combined with the conductive polymer.
• Such metal plate acts a role of connecting the conductive polymer to an external electrode and should not deteriorate the PTC characteristics of the conductive polymer. For such a reason, the conductive polymer should have good binding capacity to ensure electrical and mechanical combination with the metal plate.
• the binding capacity between the metal plate and the conductive polymer generally has two characteristics: mechanical binding capacity and chemical binding capacity.
• mechanical binding capacity a process of increasing surface roughness of the metal plate is required to restrain separation of the metal plate and the conductive polymer.
• metal plates show significantly different binding capacities to the polymer depending on their kinds, which are originated from difference of chemical binding capacities between the metal and the polymer.
• the chemical binding capacity increases in order of copper, iron, nickel, aluminum, zinc and so on. Therefore, the metal plate to be combined with polymer might be processed by scaling, surface-treatment using brass or zinc, or adhesive application using silane group.
• the electroplating is a representative method to increase surface roughness of the metal plate for restraining separation of the metal plate and the conductive polymer.
• a copper plating foil used in a printed circuit boards (hereinafter, referred to as PCB) and a metal plate used in an electrical device having PTC characteristics are manufactured using such method.
• the copper plating foil for the PCB is made to have 10 to 150 ⁇ m
• a copper foil is laminated on a base plate and then given heat and pressure thereto.
• the copper foil should have chemical resistance, such as against an acid, and resistance against discoloration of the board after etching after being attached to the base plate, and is required not to rust after etching.
• a surface of the copper foil for the PCB may be coated by a layer containing zinc, indium, brass or the like (Japanese Patent Publication No. 51-35711), or use an electrodeposited copper layer having two layers (Japanese Patent Publication No. 53-39376).
• the copper-zinc layer may be formed by electrolyzing one surface of the copper foil in a copper-zinc electrolytic bath containing copper ion, zinc ion, tartar acid and alkali with the cathode and then treating chromate on the cupper foil (U.S. Patent No. 5,304,428).
• the conventional electrode made by electrolytic plating or electrodeposition shows uneven thickness, which causes the electrode to be separated from the PTC polymer. Therefore, inventors of the present invention have endeavored to solve such problems and developed an electrode with even thickness by executing electroless plating to the electrolytic cupper foil used for the PCB.
• An object of the present invention is to provide an electrical device, which is made by combining metal electrodes, in which electroless nickel plating with even thickness is formed on an electrolytic copper foil, with PTC conductive polymer, so ensuring improved PTC characteristics and good chemical and mechanical binding capacity between the electrodes and the PTC conductive polymer.
• the present invention provides an electrical device having Positive Temperature Coefficient (PTC) conductive polymer, which includes electrodes having electroless-plated nickel layers at both sides of an electrolytic copper foil, and PTC conductive polymer welded between the electrodes, wherein the electroless-plated nickel has even thickness to ensure sufficient binding capacity to the PTC conductive polymer.
• PTC Positive Temperature Coefficient
• the electrolytic copper foil has surface roughness
• the electroless-plated nickel layer has a
• FIG. 1 is a surface photograph of an electrolytic copper foil used in the present invention
• FIG. 2 is a surface photograph of a specimen that the electrolytic copper foil is electroless nickel-plated of l ⁇ m in thickness;
• FIG. 3 shows an electrical device according to the present invention.
• FIG. 4 is a resistance-temperature graph of the electrical devices according to first to third embodiments of the present invention.
• the present invention suggests an electrical device including conductive polymer with PTC (Positive Temperature Coefficient) characteristics and electroless-plated metal electrodes.
• the PTC conductive polymer is welded between the electrodes in a sandwich type.
• the conductive polymer with PTC characteristics may be obtained by mixing conductive filler, cross-linking agent, antioxidant, etc. to organic polymer.
• the organic polymer can be one of polyethylene or ethylene-acrylic acid copolymer, ethylene-ethyl aciylate copolymer, ethylene-vinyl acetate copolymer and ethylene-butyl aciylate copolymer. Among them, polyethylene is most preferred.
• the conductive filler powder nickel, gold dust, powder copper, silvered powder copper, metal-alloy powder, carbon black, carbon powder or carbon graphite can be used. Among them, carbon black is most preferred.
• the metal electrode is made by electroless-plating a metal, which has good chemical binding capacity to the PTC conductive polymer, on the electrolytic copper foil having good mechanical binding capacity.
• the surface roughness Rz of the electrolytic copper foil is set to be l-20 ⁇ m through electrolytic plating in its manufacturing process.
• the electrolytic copper foil can be commercially acquired from LG Industry Co., which is specially used in this invention.
• the electrolytic copper foil is electroless-plated with nickel.
• the electroless nickel-plating procedure includes a degreasing process, a pickling process, an actuating and sensitizing treatment, an electroless nickel-plating process and a rinsing process.
• FIG. 2 a specimen, which is electroless-plated with nickel of l ⁇ m in thickness, is shown in FIG. 2. Seeing FIG. 2, it can be easily known that the surface roughness and shape of the specimen have no significant difference.
• the metal electrodes 2, in which the nickel is electroless-plated on the copper, are welded at both side of the PTC conductive polymer 1 to make the electrical device. This is well shown in FIG. 3.
• Polyethylene and carbon black are mixed to make PTC conductive polymer.
• electroless nickel-plating layer of l ⁇ m in thickness is formed on the electrolytic copper foil through a degreasing process, a pickling process, an actuating and sensitizing treatment, an electroless nickel-plating process and a rinsing process, to make electrodes.
• the electrodes are welded to both sides of the PTC conductive polymer in a sandwich type, so making the PTC electrical device as shown in FIG. 3.
• Embodiment 2 Polyethylene and carbon black are mixed to make PTC conductive polymer.
• An electrolytic copper foil having a surface roughness of 5 to
• nickel-plating layer of lO ⁇ m in thickness is formed on the electrolytic copper foil through a degreasing process, a pickling process, an actuating and sensitizing treatment, an electroless nickel-plating process and a rinsing process, to make electrodes.
• the electrodes are welded to both sides of the PTC conductive polymer in a sandwich type, so making the PTC electrical device as shown in FIG. 3.
• An electrical device is prepared in a similar method to the Embodiment 1. However, the actuating and sensitizing treatment is excluded from the electroless-plating procedure, and the electroless nickel-plating process is executed just after the pickling process. And then, chromium is coated on the electroless nickel-plating layer through substitution plating in a chromium bath. Comparative Example
• FIG. 4 Resistance changes depending on temperature of the electrical devices according to the embodiments 1 to 3 are shown in FIG. 4.
• the electrical devices of the present invention show no significant difference in resistance-temperature characteristics, compared with an electrical device using a conventional electrolytic copper foil. It means that the electrical device of the present invention not only strengthens binding capacity between the PTC conductive polymer and the electrodes but also maintains its resistance-temperature characteristics as much as the electrical device using the conventional electrolytic copper foil.
• the electrical device using copper electrodes of the comparative example shows significant difference in its resistance value before and after the humidity test. But, a resistance value of the electrical device using the electroless nickel plating according to the embodiment 1 does not decrease more than 10m ⁇ after the humidity
• the electrical device of the present invention gives more improved PTC characteristics and better binding capacity between the PTC conductive polymer and the electrodes than the conventional electrical device employing electrolytic plating or electrodeposition.
• the electroless plating employed in the present invention has an advantage that it may plate an object having uneven surfaces more uniformly than the electrolytic plating or the electrodeposition. Therefore, the electrical device of the present invention employing the electrodes, in which nickel is electroless-plated on the electrolytic copper foil, gives the advantages of better mechanical and chemical binding capacity to the PTC conductive polymer and more improved PTC characteristics.

Landscapes

• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Ceramic Engineering (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Chemically Coating (AREA)
• Thermistors And Varistors (AREA)
• Electroplating Methods And Accessories (AREA)
• Resistance Heating (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Related Child Applications (2)

Publications (1)

Family

ID=19662812

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (2)

Citations (3)

Family Cites Families (4)

• 2000
  • 2000-04-08 KR KR1020000018453A patent/KR100330919B1/ko not_active IP Right Cessation
• 2001
  • 2001-03-30 WO PCT/KR2001/000523 patent/WO2001078453A1/en active Application Filing
  • 2001-03-30 AU AU2001244810A patent/AU2001244810A1/en not_active Abandoned
  • 2001-03-30 CN CNB018066844A patent/CN1210994C/zh not_active Expired - Fee Related
  • 2001-03-30 JP JP2001575773A patent/JP3833538B2/ja not_active Expired - Fee Related
  • 2001-03-30 EP EP01917935A patent/EP1275273A4/en not_active Withdrawn
  • 2001-04-02 TW TW090107842A patent/TW480496B/zh not_active IP Right Cessation

Patent Citations (3)

Non-Patent Citations (1)

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