Btu International, Inc.

Francis C Nutter

David S Harvey

Martin I Soderlund

Arthur Waugh

Robert P Couilliard

Gerald E Waldron

Pierre J LeMieux

Richard J Nihan

Mark Hutchings

Brian O'Leary

David A Bloom

Martin I Soderland

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 boroscope viewing assembly allows viewing of the process chamber of a solder reflow furnace. A boroscope is removably supported within a cylindrical viewing port permanently mounted through the furnace housing. Coolant gas is flowable along the viewing port annularly surrounding the boroscope to cool the boroscope. The flow of coolant into the process chamber keeps flux vapors away from the boroscope. A sealing assembly seals the boroscope to the viewing port. The sealing assembly can be a gland fitting on the boroscope eyepiece or a compression sealing assembly. When the boroscope is removed, a plug can be placed in the end of the viewing port to seal the process chamber.

Solder reflow furnace having a boroscope viewing assembly

An apparatus and method for cooling one side of a double sided product as the product is being reflow soldered is presented. A cooling assembly directs cold gas to a first side of the product which has previously had the first side reflow soldered, while at approximately the same time, a heating assembly directs hot gas to a second side of the product. The second side of the product is reflow soldered while the first side of the product is maintained at a temperature below the melting point of the solder.

Apparatus and method for solder reflow bottom cooling

A boat carrier for accommodating multiple width integrated circuit (IC) boats is provided. The boat carrier comprises a base member and opposed guide faces which abut side surfaces of IC boats of multiple widths. In a first embodiment, the boat carrier includes a first guide having a first guide face affixed to the base member, and a movable guide having a movable guide face releasably affixed to the base member. The movable guide face has a first position and a second position, whereby a narrower IC boat is receivable in the first position and a wider IC boat is receivable in the second position. In a further embodiment, the boat carrier comprises a base member, a fixed guide assembly having a fixed guide face, and an opposed guide assembly having an inner and outer guide face, whereby a boat having a first or second width is receivable. In yet another embodiment, the boat carrier comprises a further fixed guide assembly and a further opposed guide assembly, thereby forming dual sets of guides, wherein each set of guides is capable of receiving a boat having a first or second width.

Multiple width boat carrier for vertical ovens

A vortex tube cooling system is presented. The cooling system contains one or more vortex tubes connected to a supply of compressed gas, the vortex tubes providing a stream of cold gas which cools product as it emerges from a furnace. The cooling system is particularly useful for cooling circuit boards emerging from a solder reflow convection furnace.

Vortex tube cooling system for solder reflow convection furnaces

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.

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Methuen, MA, United States of America

Francis C Nutter