International Business Machines Corporation

Other

James Sherill Akin

Thomas Alan Schiesser

Ted Minter Smith

John Andrew Shriver, Iii

Edward Blakley Menard

A method and implementing system is provided in which a gas, such as oxygen, is injected on to area of a circuit board to which an electronic component is being mounted. The injected gas causes a formation of a coating or surface alloy layer such as tin-oxide, on the solder joint. The coating causes the solder bead or joint to have a higher surface tension and a higher reflow temperature. In an exemplary double-sided double-pass assembly operation, circuit boards pass through a soldering oven on a first pass to attach components to a first side, and then the board is inverted and passed through the oven on a second pass while components are mounted on the opposite side of the board. During the second pass, a gas injection device is aimed at the component-to-board connection points on the inverted side of the board which were soldered on the first pass. The gas is injected at the point in the soldering reflow oven at which the temperature begins to exceed the solder reflow temperature. The gas injection is effective to cause the formation of a surface layer on the solder bead thereby increasing the surface tension between the circuit board and the mounted component during the second pass reflow.

Circuit board component retention

A method and system for introducing flux onto at least one surface of a solder pump achieve their objects as follows. A solder pump nozzle is submerged into a flux reservoir. In response to such submersion, the flux in the reservoir is actively introduced into the solder pump nozzle. In one embodiment, the active introduction is achieved by creating a negative pressure in a solder pump nozzle such that flux fills a vacated volume. The created negative pressure is produced by moving a solder column, contained within the solder pump nozzle, under the influence of an applied electric current and an applied magnetic field.

Method and system for introducing flux onto at least one surface of a

The size and shape of molten solder droplets ejected from a nozzle of a droplet pump are stabilized using flux transported into the aperture region of the nozzle through which the droplets are ejected. The flux is periodically replenished as necessary to remove solder oxides and dross, as well as to lubricate the aperture. The flux may be deposited by spraying onto the nozzle, submersion of the nozzle, contact of the nozzle to a flux film, contact of the nozzle with an intermediate transfer medium, or through injection internal to the nozzle assembly. Fluxes exhibiting high activity and high thermal stability at elevated temperatures are preferred.

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Round Rock, TX, United States of America

James Sherill Akin