Patent ID: 6606023
Filing Date: 2003-08-12
Classification: H01C

Abstract:
A composite circuit protection device comprising(I) a laminar insulating member; (II) a first laminar circuit protection device; and (III) a second laminar circuit protection device; each of the first and second laminar circuit protection devices comprising (1) a first laminar electrode; (2) a second laminar electrode; (3) a laminar PTC resistive element which (i) exhibits PTC behavior, (ii) has a first face to which the first electrode is secured and an opposite second face to which the second electrode is secured, (iii) defines first and second apertures which run between the first and second faces, and (iv) is composed of a PTC conductive polymer; (4) a third laminar conductive member which (i) is secured to the second face of the PTC resistive element in the area of the first aperture, and (ii) is spaced apart from the second electrode; (5) a fourth laminar conductive member which (i) is secured to the first face of the PTC resistive element in the area of the second aperture, and (ii) is spaced apart from the first electrode; (6) a first transverse conductive member which (a) lies within the first aperture defined by the PTC resistive element, (b) runs between the first and second faces of the PTC element, (c) is secured to the PTC element, and (d) is physically and electrically connected to the first laminar electrode and to the third laminar conductive member, but is not connected to the second laminar electrode; and (7) a second transverse conductive member which (a) lies within the second aperture defined by the PTC resistive element, (b) runs between the first and second faces of the PTC element, (c) is secured to the PTC element, and (d) is physically and electrically connected to the second laminar electrode and to the fourth laminar conductive member, but is not connected to the first laminar electrode; the first and second laminar devices being physically secured together in a stacked configuration, with the laminar insulating member between them; the devices being connected together electrically by interfacial electrical connections which are solder joints composed of a first solder and are between(A) a third or fourth member of the first laminar device and a first or second electrode of the second laminar device, and (B) a third or fourth member of the second laminar device and a first or second electrode of the second laminar device so that when an electrical power supply is connected to (i) one of the electrodes and (ii) the third or fourth laminar member on the same face of the PTC resistive element as the electrode (i), the first and second laminar circuit protection devices are connected electrically in parallel;the composite device (1) being capable of flat connection onto a substrate free of leads, and (2) further comprising layers of a second solder on exposed surfaces of the first or second electrodes and the third and fourth laminar members, the second solder being reflowable at temperatures which do not melt the solder joints.