Method and apparatus for fluxing and soldering terminals on a printed circuit board

A method of fluxing and soldering terminals on a printed circuit board comprising:

• moving the printed circuit board along a passline through a flux application station while directing a wall of flux across a surface of the board;
• in each of a plurality of locations laterally of the passline, passing infrared light having a range of wavelengths through the wall of flux to cause different wavelengths of the infrared light to be absorbed at least partially by different materials in the flux;
• receiving the unabsorbed infrared light which has passed through the wall at each of the locations;
• for each location, generating signals corresponding to the different wavelengths of unabsorbed light at that location and thus corresponding to the actual flux concentration at that location, and when the signals differ from a datum signal which corresponds to the desired flux concentration at that location, effecting a change in flow of flux to change the actual flux concentration towards that desired;
• and moving the board carrying the flux on said surface towards and through a solder application station to apply solder to the terminals.

A wave soldering apparatus comprising:

• a flux application station, and a solder application station disposed downstream of the flux application station along the passline for printed circuit boards to be passed through the apparatus;
• means for creating a wall of flux in the flux application station and for directing it upwardly towards the passline to coat with flux printed circuit boards as they move through the application station;
• means for passing infrared light at a plurality of locations spaced laterally of the passline through the wall of flux and means for receiving infrared light which is unabsorbed by the materials of the flux in the wall and which has passed through the wall, the infrared light having an operating range of wavelengths;
• and means for generating signals corresponding to the different wavelengths of unabsorbed infrared light at each of the plurality of locations to enable a determination to be made of the flux concentration at that location.

A wave soldering apparatus comprising:

• a flux application station, and a solder application station disposed downstream of the flux application station along a passline for printed circuit boards to be passed through the apparatus;
• means for creating a wall of flux in the flux application station and for directing the wall of flux upwardly towards the passline to coat with flux printed circuit boards moving through the application station;
• means for adjusting the flux concentration to any of the plurality of locations spaced laterally of the passline;
• means for transmitting infrared light through the wall of flux at each of the plurality of locations and means for receiving infrared light which is unabsorbed by the materials of the flux in the wall and which has passed through the wall, the infrared light having an operating range of wavelengths;
• means for generating signals corresponding to the different wavelengths of unabsorbed light at each of the locations, the generated signals also corresponding to actual flux concentrations at that location;
• and means to effect a change in the flux concentration at any of the locations towards a desired flux concentration when a generated signal at that location differs from a datum signal which corresponds to the desired flux concentration.