The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 23, 1991
Filed:
Nov. 29, 1988
Homer E Henschen, Carlisle, PA (US);
Michael J McKee, New Cumberland, PA (US);
Joseph M Pawlikowski, Lancaster, PA (US);
AMP Incorporated, Harrisburg, PA (US);
Abstract
A heater (20,40,50,70,80) is secured to or embedded in a circuit board (10,30,75,86) and is selectively energizable by current to melt solder in a connection or disconnection operation. The heater is spaced from circuit board contact pads (13,34) by circuit board structure material that transmits the generated thermal energy to the contact pads to melt solder or other fusible material. The heater is a self-regulating heater in the form of a copper substrate having a thin surface layer of magnetically permeable, high resistance material. An alternating current of constant amplitude and high frequency is passed through the heater and concentrated in the surface layer at temperatures below the surface layer Curie temperature. At higher temperatures the current is distributed through the lower resistance substrate to limit further heating. A current return path (21,43,53,73,85) or bus is disposed in closely-spaced parallel relation to the surface layer and establishes an electric field between the substrate and the return bus to bias current in the substrate toward the surface layer. The return bus may be embedded in the circuit board or provided as part of external tooling employed to deliver energizing current.