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:
Mar. 18, 1997
Filed:
Jan. 18, 1996
Martin I Soderlund, Westborough, MA (US);
Francis C Nutter, Methuen, MA (US);
Robert P Couilliard, Plaistow, NH (US);
Pierre J LeMieux, Andover, MA (US);
Arthur Waugh, Winchester, MA (US);
BTU International, No. Billerica, MA (US);
Abstract
A solder reflow convection furnace employing flux collection and heating to minimize flux and solvent build up and gas densification to reduce input gas flow is disclosed. As solder melts in the furnace, an effluent of vaporized flux is driven off and can condense on cooler components. To minimize such condensation, the gas is directed through a cooling system in which the flux condenses, and the cooled, cleaned gas is directed into the furnace's product cooling section. In another embodiment, in which the gas in the furnace is recirculated, a cooling coil is located upstream of the recirculating gas mover to heat the primary gas. The vaporized flux condenses on the cooling coil, which can be readily removed and replaced. In another aspect of the invention, when the furnace employs a gas amplifier, the recirculating gas is cooled prior to reentry into the heating chamber, which increases its density and removes flux by condensation. Upon reentering the heating chamber, the cooler, denser gas undergoes a greater expansion than would return hot gas, thereby increasing the pressure in the chamber and correspondingly increasing the velocity of the output flow to the process area. The increased velocity allows reduction of consumption of the primary gas and increases the efficiency of heat transfer.