Metal fusion bonding – Process – With protecting of work or filler or applying flux
Patent
1989-10-10
1991-12-10
Heinrich, Samuel M.
Metal fusion bonding
Process
With protecting of work or filler or applying flux
228223, 228 42, 427432, B23K 3538, H05K 334
Patent
active
050710583
ABSTRACT:
This invention relates to a method of conducting a joining/coating operation which provides good wetting of metal-comprising substrate surfaces by metal-comprising filler/coating materials while reducing the rate of metal oxide formation. The joining/coating operation is carried out in a controlled oxidizing atmosphere having an oxidation capability greater than that required to oxidize a metal-comprising filler material used for joining or a metal-comprising coating, but having less oxidation capability than that of air. Typically the controlled oxidizing atmosphere consists essentially of nitrogen and oxygen, wherein the oxygen concentration is controlled at a set point. The range of the setpoint corresponds with an oxygen concentration which can range from greater than about 10 ppm to about 100,000 ppm, depending on the application. When a flux is used and the joining technique is reflow soldering, the setpoint for oxygen concentration can range from greater than about 100 ppm to less than about 50,000 ppm of oxygen, depending on the application, with a preferred range from about 500 ppm to about 10,000 ppm. When a flux is used and the joining technique is wave soldering, the setpoint for oxygen concentration can range from about 1,000 ppm to about 100,000 ppm of oxygen depending on the application, with a preferred range from about 10,000 ppm to about 20,000 ppm. Joining/coating operations conducted without use of a flux require a joining/coating atmosphere having a lower oxidation capability, but still capable of oxidizing the metal-comprising filler material/metal-comprising coating material.
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Fritschler Alvin H.
Heinrich Samuel M.
Kent Peter
Union Carbide Industrial Gases Technology Corporation
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