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| Al-Si-Sn Bearing Alloy and bearing composite |
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| Aluminum based bearing alloys |
| What is claimed as new and desired to be secured by Letters Patent of the United States is: 1. An ... |
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| Aluminum-lead engine bearing alloy metallurgical structure and method of making same |
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| Aluminum alloy bearing |
| The present invention concerns an aluminum alloy for shaft bearings wherein the alloy contains ... |
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| Puncture-sealing pneumatic tire and a method of producing the tire |
| OF THE PREFERRED EMBODIMENTS In the FIGURE, the numerals 1, 2, 3 and 4 represent a tire, a bead ... |
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| Method of manufacturing supports for porous filters |
| We claim: 1. A method of manufacturing filter supports, wherein rigid macroporous supports having ... |
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| Safety pneumatic tire |
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| Self-sealing pneumatic tire |
| OF THE INVENTION FIG. 1 is a cross-sectional view of the self-sealing pneumatic tire of this ... |
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Process for reflow soldering
| Details |
Inventors: Bandyopadhyay, Nikhiles; Kirschner, Mark J.;
Assignee: The BOC Group, Inc. (Murray Hill, NJ)
Primary Examiner: Heinrich; Samuel M.
Assistant Examiner:
Attorney, Agent or Firm: Nemetz; Carol A., Pearlman; Robert I.
A method of joining components to a substrate by reflow soldering with non-rosin-based flux containing solder is disclosed comprising heating the solder in the presence of the components in a low oxidizing atmosphere. |
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DETAILED DESCRIPTION OF THE INVENTION The atmosphere of the present invention is a low oxidizing atmosphere.
It preferably comprises no more than about 1500 parts per million of oxygen; no more than about 1.
5 percent by volume of water vapor; and a primary selected from the group consisting of nitrogen, carbon dioxide, hydrogen, an inert gas or mixtures thereof; wherein if water vapor or oxygen is present, hydrogen will be present in an amount effective to reduce the oxidation potential of the water vapor or oxygen; and wherein if neither oxygen nor water vapor is present, then said primary gas is selected from the group consisting of nitrogen, carbon dioxide, hydrogen or mixtures thereof.
Further preferred are atmospheres wherein water vapor comprises from about 0.
5 percent by volume to about 1.
5 percent by volume of the atmosphere.
Additionally, preferred are atmospheres wherein hydrogen comprises from about 2 to about 20 percent by volume of the total volume of the atmosphere, remembering that hydrogen is always present in an effective amount to reduce the oxidation potential of any water vapor or oxygen present in the atmosphere.
The oxidation potential of each of water vapor and oxygen or the net oxidation potential of the two combined must be so low that little or no residue is formed during reflow soldering.
This results in hydrogen generally being present in amounts by volume greater than the amount of water vapor, as hydrogen will reduce the oxidation potential of water.
Oxygen is limited to merely trace amounts so that oxidation will not occur and will not thereby interfere with the soldering process.
Hydrogen also reduces the oxidation potential of oxygen.
Any of the inert gases are satisfactory in the present invention.
However, if neither oxygen nor water vapor is present then the primary gas is nitrogen, carbon dioxide, hydrogen or mixtures thereof.
The most preferred atmosphere of the present invention comprises, by volume, about 1 percent of water vapor, about 15 percent of hydrogen and about 84 percent of nitrogen
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Manufacturing Materials 
