Abstract A soldering iron is disclosed in which a self-regulating heating element is employed. In one embodiment the heating element is mounted within a cavity provided in the soldering tip in optimum heat transfer relation with the tip. The heating element is composed of a material having a steeply sloped positive temperature coefficient (PTC) of resistivity and locked into the tip cavity with a thermally conductive encapsulent. A thin layer of electrically insulative material may be provided separating the heater from the encapsulent. Means are provided to apply line voltage across the heating element causing a relatively high current inrush, due to the low resistance of the heater at room temperature, with a concomitant large quantity of generated heat until the anomaly temperature of the heater element is reached at which point the resistance rapidly increases to effectively decrease power generation, maintaining a balance between power dissipated and power generated. A second embodiment employs the heater element also as the applicator tip. One end of the heater element is formed with a pyramidic configuration, the outer portions of which are converted to an electrically insulating state and plated with a metallic surface to facilitate soldering. The heater is encapsulated in an insulating sleeve with the tip projecting therefrom. As in the previous embodiment, means are provided to apply line voltage across the heater element causing it to heat up.
In a heat applicator, an applicator tip, a heater element mounted in heat transfer relation to the applicator tip, the heater element and tip comprising a unitary member composed of material having a steeply sloped positive temperature coefficient of resistivity above an anomaly temperature, at least the surface of said tip being treated to render it electrically nonconductive, and means to apply a voltage across the element causing electrical current to flow through the element, thereby causing the element to heat up to its operating temperature.
Claim 2
Dependent Claim
86 words
In a heat applicator, an applicator tip, a heater element mounted in heat transfer relation to the applicator tip, the heater element and tip comprising a unitary member composed of material having a steeply sloped positive temperature coefficient of resistivity above an anomaly temperature, at least the surface of said tip being treated to render it electrically nonconductive, and means to apply a voltage across the element causing electrical current to flow through the element, thereby causing the element to heat up to its operating temperature.
Claim 3
Dependent Claim
37 words
An applicator according to claim 1 in which the means to apply a voltage across the element includes layers of conductive material attached to spaced portions of the element and an electrical lead attached to each layer.
Claim 4
Dependent Claim
54 words
A heat applicator according to claim 1 in which said member is mounted in a tubular shank attached to a handle, the heater element portion of the member being inserted into the tubular shank with the tip extending beyond the shank and encapsulating material is lockingly inserted between the heater element and the shank.
Claim 5
Dependent Claim
13 words
A heat applicator according to claim 1 in which the tip is pyramidical.
Claim 6
Dependent Claim
25 words
A heat applicator according to claim 1 in which at least a portion of the surface of the tip is coated with a metal layer.