Chip PTC thermistor and method for manufacturing the same

• US 20040252006A1
• Filed: 07/19/2004
• Published: 12/16/2004
• Est. Priority Date: 07/07/1997
• Status: Active Grant

• Current Assignee: CYG Wayon Circuit Protection Co., Ltd.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ikeda, Takashi, Iwao, Toshiyuki, Kojima, Junji, Morimoto, Kohichi
• Granted Patent: US 7,183,892 B2
• Time in Patent Office: Days
• US Class Current: 338/22R
• CPC Class Codes: H01C 1/1406 Terminals or electrodes formed on resistive elements having positive temperature coefficient
• CPC Class Codes: H01C 17/006 adapted for manufacturing resistor chips
• CPC Class Codes: H01C 7/02 having positive temperature coefficient ceramics C04B
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: Y10T 29/49082 Resistor making
• CPC Class Codes: Y10T 29/49083 Heater type
• CPC Class Codes: Y10T 29/49085 Thermally variable
• CPC Class Codes: Y10T 29/49099 Coating resistive material on a base

Abstract

Chip PTC thermistors that can easily be inspected the soldered portions after it is mounted on a printed circuit board and that can be used in a flow soldering process, and methods of making same. A chip PTC thermistor of the present invention includes: a first main electrode and a first sub-electrode on first surface of a cuboidal form conductive polymer having the PTC characteristics, a second main electrode and a second sub-electrode on a second surface opposite the first surface of the conductive polymer. Between the first sub-electrode and the second sub-electrode, and between the first sub-electrode and the second main electrode are electrically connecting with a first side electrode and a second side electrode, respectively.

Claims

1. A chip PTC thermistor comprising:

a cuboidal base comprising a conductive polymer having PTC characteristics;

a first main electrode on a first surface of said conductive polymer base;

a first sub-electrode on the same surface as said main electrode, yet being independent from said first main electrode;

a second main electrode on a second surface of said conductive polymer base opposite said first surface;

a second sub-electrode on the same surface as said second main electrode, yet being independent from said second main electrode;

a first side electrode covering at least an entire surface of one side surface of said conductive polymer base, said first side electrode being electrically connected with said first main electrode and said second sub-electrode; and

a second side electrode covering at least an entire surface of a second side surface opposite said one side surface of said conductive polymer base, said second side electrode being electrically connected with said first sub-electrode and said second main electrode, wherein at least one of a side surface of said first main electrode and a side surface of said second main electrode is not exposed outside other side surfaces of said conductive polymer base.

4. The chip PTC thermistor of claim 1, wherein the first and second side electrodes are formed of nickel or nickel alloy.

2. A chip PTC thermistor comprising:

a cuboidal base comprising a conductive polymer having PTC characteristics;

a first main electrode on a first surface of said conductive polymer base;

a first sub-electrode on a same surface as said main electrode, yet being independent from said first main electrode;

a second main electrode on a second surface opposite said first surface of said first surface of said conductive polymer base;

a second sub-electrode on a same surface as said second main electrode, yet being independent from said second main electrode;

a first side electrode covering at least an entire surface of one side surface of said conductive polymer base, said first side electrode being electrically connected with said first main electrode and said second sub-electrode;

a second side electrode covering at least an entire surface of a second side surface opposite said one side surface of said conductive polymer base, said second side electrode being electrically connected with said first sub-electrode and said second main electrode;

one or more odd numbered inner main electrodes disposed within said conductive polymer in parallel with said first and second main electrodes;

one or more odd numbered inner sub-electrodes disposed at a same plane as said one or more inner main electrodes, yet being electrically independent from said one or more inner main electrodes;

wherein

(1) said inner main electrode immediately opposite said first main electrode is electrically connected with said second side electrode, while said inner sub-electrode disposed at the same plane as said inner main electrode immediately opposite said first main electrode is electrically connected with said first side electrode;

(2) said inner main electrode and inner sub-electrode disposed adjacent each other are electrically connected, alternately, with said first side electrode and said second side electrode, and

(3) at least one of a side surface of said first main electrode and a side surface of said second main electrode is not exposed outside other side surfaces of said conductive polymer base.

17. The chip PTC thermistor of claim 2, wherein the first and second side electrodes are formed of nickel or nickel alloy.

3. A chip PT thermistor comprising:

a cuboidal base comprising a conductive polymer having PTC characteristics;

a first main electrode on a first surface of said conductive polymer base;

a first sub-electrode disposed on a same surface as said main electrode, yet being independent from said first main electrode;

a second main electrode on a second surface of said conductive polymer opposite said first surface;

a second sub-electrode on a same surface as said second main electrode, yet being independent from said second main electrode;

a first side electrode covering at least an entire surface of one side surface of said conductive polymer base, which first side electrode is electrically connected with said first main electrode and said second sub-electrode;

a second side electrode covering at least an entire surface of a second side surface opposite said one side surface of said conductive polymer base, said second side electrode being electrically connected with said first sub-electrode and said second main electrode;

even numbered inner main electrodes disposed within said conductive polymer in parallel with said first and second main electrodes;

even numbered inner sub-electrodes disposed at a same plane as said inner main electrodes, yet being independent from said inner main electrodes;

wherein

(1) said inner main electrode immediately opposite said first main electrode is electrically connected with said second side electrode, while said inner sub-electrode disposed at the same plane as said inner main electrode immediately opposite said first main electrode is electrically connected with said first side electrode;

(2) said inner main electrodes and inner sub-electrodes disposed adjacent each other are electrically connected, alternatively, with said first side electrode and said second side electrode and

(3) at least a side surface of said first main electrode and a side surface of said second main electrode is not exposed outside other side surfaces of said conductive polymer base.

18. The chip PTC thermistor of claim 3, wherein the first and second side electrodes are formed of nickel or nickel alloy.

5-16. -16. (Canceled)