Convection/infrared solder reflow apparatus utilizing controlled gas flow

Apparatus for solder reflow of surface mounted devices to printed circuit boards, said apparatus comprising:

• a conveyor for transporting printed circuit boards having devices thereon from a first end to a second end thereof;
• a plurality of heating zones disposed between said first end and said second end of said conveyor, said zones being aligned along said conveyor sequentially in closely spaced relation with respect to one another, each of said zones comprising:
• a cell having an interior;
• a gas circulation mechanism having a low pressure side and a high pressure side;
• a heater for heating gas expelled from said interior of said cell toward said conveyor by said gas circulation mechanism;
• a return channel for conducting gas from said conveyor to said low pressure side of said gas circulation mechanism;
• and
• an adjustable aperture associated with said return channel for controlling the volume of gas flowing from said conveyor to said low pressure side of said gas circulation mechanism.

Apparatus for solder reflow of surface mounted devices to circuit boards comprising:

• a housing having a first end and a second end;
• a conveyor for moving the circuit boards with devices thereon from said first end through said housing to said second end thereof;
• a first zone within said housing having a heater for heating a gas and a mechanism for circulating the gas to the conveyor from said heater and returning the gas from said conveyor to said heater;
• a first port for exhausting gas from said first zone to a location external of said housing;
• a second zone within said housing having a second heater for heating gas and a second mechanism for circulating gas from said second heater to said conveyor and returning gas from said conveyor to said second heater;
• an aperture with a closure for diverting gas from said second zone toward said first zone;
• a second port for introducing unheated gas to said second zone;
• a third zone within said housing having a third heater for heating gas and a third mechanism for circulating gas from said third heater to said conveyor and returning gas from said conveyor to said third heater;
• a third port for introducing unheated gas to said third zone;
• a fourth zone within said housing having a fourth heater for heating gas and a fourth mechanism for circulating gas from said fourth heater to said conveyor and returning gas from said conveyor to said fourth heater;
• a fourth port for exhausting gas from said fourth zone;
• and
• a second aperture with a closure for diverting gas from said third zone toward said fourth zone.

Apparatus for solder reflow of surface mounted devices to printed circuit boards, said apparatus comprising:

• a conveyor for transporting printed circuit boards having devices thereon from a first end to a second end thereof;
• a plurality of heating zones disposed between said first end and second end of said conveyor, said zones being aligned along said conveyor sequentially in closely spaced relation with respect to one another, each of said zones comprising:
• a gas circulation mechanism having a low pressure side and a high pressure side facing said conveyor;
• a heater for heating gas which is circulated from said high pressure side of said gas circulation mechanism toward said conveyor;
• and
• a return channel for conducting gas from said conveyor back to said low pressure side of said gas circulation mechanism;
• and
• apparatus for selectively diverting gas from one of said zones to another of said zones, said diverting apparatus comprising:
• apertures with closures associated with said return channels of said one zone for reducing the volume of gas returned from said conveyor to said low pressure side of said gas circulation mechanism in said one zone;
• and
• ports associated with each of said zones for selectively introducing unheated gas into said one zone and for exhausting heated gases from said other zone.

Apparatus for solder reflow of surface mounted devices to printed circuit boards, said apparatus comprising:

• a conveyor for transporting printed circuit boards having devices thereon from a first end to a second end thereof;
• a plurality of heating zones disposed between said first end and said second end of said conveyor, said zones being aligned along said conveyor sequentially in closely spaced relation with respect to one another, each of said zones comprising:
• a gas circulation mechanism having a low pressure side and a high pressure side facing said conveyor;
• a heater for heating gas which is circulated from said high pressure side of said gas circulation mechanism toward said conveyor, said heaters in first ones of said zones heating gas to a temperature higher than a temperature to which gas is heated by said heaters in second ones of said zones;
• and
• a return channel for conducting gas from said conveyor to said low pressure side of said gas circulation mechanism;
• an open exhaust port disposed in each of said first ones of said zones for exhausting gas from said high pressure sides of said gas circulation mechanisms in said first ones of said zones;
• and
• an open intake port disposed in each of said second ones of said zones for introducing unheated gas from a source outside of said zones into each of said second ones of said zones.