Electrical devices

• US 7,355,504 B2
• Filed: 11/25/2003
• Issued: 04/08/2008
• Est. Priority Date: 07/09/1992
• Status: Expired due to Fees

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Thompson, Mark, Fang, Shou-Mean, Zhang, Michael, Graves, Gregory A., Siden, Dennis, Chan, Chi-Ming, Chandler, Daniel
• Primary Examiner(s): LEE, KYUNG S
• Application Number:
  US10/721,478
• Publication Number:
  US 20040246092A1
• Time in Patent Office: 1,596 Days
• Field of Search: 338/22.R, 338/22.SD, 338/328, 338/331, 252511-512, 219/521, 219/553
• US Class Current: 338/22.00R
• CPC Class Codes: C12N 9/503 derived from viruses
• CPC Class Codes: C12N 9/52 derived from bacteria or Archaea
• CPC Class Codes: H01C 1/14 Terminals or tapping points or electrodes specially adapted for resistors in general H01R; Arrangements of terminals or tapping points or electrodes on resistors
• CPC Class Codes: H01C 1/1406 Terminals or electrodes formed on resistive elements having positive temperature coefficient
• CPC Class Codes: H01C 17/06586 composed of organic material
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: H05K 1/182 associated with components mounted in the printed circuit board, e.g. insert mounted components [IMC]
• CPC Class Codes: H05K 1/184 Components including terminals inserted in holes through the printed circuit board and connected to printed contacts on the walls of the holes or at the edges thereof or protruding over or into the holes
• CPC Class Codes: H05K 2201/09181 Notches in edge pads
• CPC Class Codes: H05K 2201/09954 More mounting possibilities, e.g. on same place of PCB, or by using different sets of edge pads
• CPC Class Codes: H05K 2201/10022 Non-printed resistor
• CPC Class Codes: H05K 2201/10469 Asymmetrically mounted component
• CPC Class Codes: H05K 2201/10643 Disc shaped leadless component
• CPC Class Codes: H05K 2201/10666 Plated through-hole for surface mounting on PCB
• CPC Class Codes: H05K 3/0097 Processing two or more printed circuits simultaneously, e.g. made from a common substrate, or temporarily stacked circuit boards H05K3/0052 takes precedence
• CPC Class Codes: H05K 3/3442 having edge contacts, e.g. leadless chip capacitors, chip carriers
• CPC Class Codes: H05K 3/403 Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof H05K3/4092 takes precedence
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49085 Thermally variable
• CPC Class Codes: Y10T 29/49101 Applying terminal
• CPC Class Codes: Y10T 29/49103 : Strain gauge making

Abstract

An electrical device which comprises first and second laminar electrodes and a laminar PTC resistive element sandwiched between them, the device comprising

• • (a) a main portion which comprises a main part of the first electrode, a main part of the second electrode, and a main part of the resistive element; and
  • (b) a first connection leg which extends away from the main portion and which comprises a first leg part of the first electrode which is integral with the main part of the first electrode, and a first leg part of the resistive element which is integral with the main part of the resistive element.
    Such devices can be secured to circuit boards in a variety of ways, and to elastically deformed terminals. Preferably preferred devices contain two laminar electrodes, with a PTC element between them, and a cross-conductor which passes through the thickness of the device and contacts one only of the two electrodes. The cross-conductor permits connection to both electrodes from the same side of the device, and also makes it possible to carry out the steps for preparing such devices on an assembly which corresponds to a number of individual devices, with division of the assembly as the final step.

Claims

1. An assembly which comprises

(1) a PTC resistive element which

(a) is composed of a resistive material which exhibits PTC behavior and has a resistivity at 25°

C. of less than 10 ohm-cm,

(b) has a first face and a second face, and

(c) defines an aperture which runs between the first and second faces;

(2) a transverse conductive member which

(a) lies within the aperture defined by the PTC element,

(b) runs between the first and second faces of the PTC element,

(c) is secured to the PTC element; and

(d) comprises metal; and

(3) a first laminar conductive member which (a) is secured to the first face of the PTC element and (b) is physically and electrically connected to the transverse conductive member.

2. A circuit protection device which has a resistance of less than 15 ohm and a maximum dimension of at most 12 mm, and which comprises

(1) a laminar PTC resistive element which

(a) is composed of a conductive polymer which has a resistivity at 25°

C. of less than 50 ohm-cm and which exhibits PTC behavior, and

(b) has a first face and second face;

(2) a first metal foil electrode which contacts the first face of the PTC element;

(3) a second metal foil electrode which contacts the second face of the PTC element; and

(4) an additional metal foil conductive member which contacts the second face of the PTC element and is spaced apart from the second electrode;

the PTC element, the first electrode and the additional conductive member defining an aperture which runs between the first electrode and the additional conductive member, through the PTC element; and

(5) a transverse conductive member which

(a) is composed of metal,

(b) lies within the aperture, and

(c) is physically and electrically connected to the first electrode and the additional conductive member.

3. An electrical assembly which comprises

(A) a printed circuit board including first and second conductive traces on a surface thereof, and

(B) an electrical device which comprises

(1) a laminar PTC resistive element which

(a) is composed of a resistive material which exhibits PTC behavior, and

(b) has a first face and a second face;

(2) a first laminar electrode which is secured to the first face of the PTC element;

(3) a second laminar electrode which is secured to the second face of the PTC element;

(4) an additional laminar conductive member which (a) is secured to the second face of the PTC element and (b) is spaced apart from the second electrode;

the PTC element, the first electrode and the additional laminar conductive member defining an aperture which runs between the first electrode and the additional conductive member, through the PTC element; and

(5) a transverse conductive member which

(a) lies within the aperture, and

(b) is physically and electrically connected to the first electrode and the additional conductive member;

said electrical device being placed on the printed circuit board and parallel thereto, with the first conductive trace physically and electrically connected to the additional conductive member, and the second conductive trace physically and electrically connected to the second electrode.

4. An assembly which comprises

(1) a laminar PTC resistive element which (i) is composed of a resistive material exhibiting PTC behavior and having a resistivity at 25°

C. of less than 10 ohm-cm, and (ii) has a first face and a second face,

(2) a first laminar conductive member which is secured to the first face of the PTC element, and

(3) a second laminar conductive member which is secured to the second face of the PTC element;

the PTC element and the first and second laminar conductive members defining a plurality of apertures which pass through the thickness of the assembly, and the apertures being arranged in a regular pattern.