Btu International, Inc.

Btu Engineering Corporation

Martin I Soderlund

Francis C Nutter

Arthur Waugh

David S Harvey

Robert P Couilliard

Pierre J LeMieux

Brian O'Leary

R Chester Pray

A forced convection furnace gas plenum having a mixing chamber to provide a heated gas of a more uniform temperature is presented. The plenum includes a heating element for heating gas and an orifice plate for metering the flow of heated gas to product within the furnace. A heater plate having larger apertures than those of the orifice plate is disposed between the heating element and the orifice plate. The apertures in the heater plate are sized to allow heated gas to pass therethrough into the mixing chamber, located between the heater plate and the orifice plate, with minimal pressure loss. The heated gas mixes in the mixing chamber, causing the temperature to become more uniform before the gas exits through the orifice plate to impinge on the product.

Forced convection furnance gas plenum

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.

Solder reflow convection furnace employing flux handling and gas

A muffle seal for a high temperature furnace in which a quartz or similar muffle is attached to an associated metal structure to provide substantial sealing of gas in the muffle even at extremely high operating temperatures. As employed in a multi-zone furnace having a high temperature quartz muffle section and a lower temperature metal muffle section joined thereto via a gas or gas and heat barrier, the quartz muffle is joined to the barrier by a peripheral chamber provided around the end of the quartz muffle confronting the barrier, the chamber being sealed to surfaces of the muffle and the barrier by porous gaskets. A sealing gas is introduced at above atmospheric pressure to the peripheral chamber, the gas being controllably transmitted through the porous gaskets to provide isolation against leakage of gas within the quartz muffle. The novel seal can also be employed to join quartz and metal muffle sections without a barrier therebetween.

High temperature furnace muffle

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Westborough, MA, United States of America

Martin I Soderlund