Dross removal

This invention relates to devices, systems, and methods for handling molten solder, and more particularly to devices, systems, and methods for separating dross, carried by molten solder, into solder and residue.

Dross is a byproduct of soldering processes, such as wave soldering. Dross includes oxides of the metals of which the solder is composed, contaminants which come from flux and/or other agents used in the soldering process, and some usable solder. In particular, during oxidation, nuclei of solder are formed which are enveloped by oxides. Clusters of such units form the dross. Dross can disrupt the soldering process.

Dross has a density that is less than that of solder so that dross typically floats on molten solder. Known methods of dealing with dross include scooping the dross off the surface of molten solder. However, when the dross is scooped away, not only are metal oxides and contaminants removed, but also some usable solder.

The invention is based, in part, on the discovery that a gas can be injected into molten solder to aid in the separation of dross into reusable solder and a residue.

In general, the invention features systems for separating dross into reusable solder and a residue. The systems include a vessel configured to receive and contain molten solder, and a gas injection circuit arranged to inject one or more gases into molten solder disposed within the vessel.

In some implementations, the gas injection circuit is configured to inject the gas into the vessel in a region below a surface level of molten solder disposed within the vessel.

In some embodiments, the gas injection circuit comprises one or more gas injection pipes at least partially disposed within the vessel. In some cases, the gas injection pipe is configured to deliver the gas into the vessel. The gas injection circuit can also include a gas source in fluid communication with the gas injection pipe. The gas injection pipe can be configured to deliver gas from the gas source into the vessel. In some examples, the gas injection pipe is at least partially disposed within the vessel in a position below a surface level of molten solder disposed within the vessel.

In some implementations, the gas injection circuit includes a gas source, and a gas injection pipe at least partially disposed within the vessel. The gas injection pipe can include a first opening in fluid communication with the gas source, and one or more apertures disposed within the vessel and in fluid communication with the first opening. The gas injection pipe can be arranged to convey one or more pressurized gases from the gas source to the separating vessel.

In some embodiments, the systems can also include at least one knife extending at least partially into the vessel and arranged to contact a flow of molten solder disposed within the vessel. The at least one knife can be mounted for movement relative to the vessel thereby to cut through dross carried by molten solder within the vessel. In some cases, the gas injection circuit includes a plurality of gas injection pipes disposed within the separating vessel and arranged around the at least one knife. The plurality of gas injection pipes can be configured to deliver gas into molten solder within the separating chamber. In some examples, the gas injection pipes are substantially parallel to a motion axis of the at least one knife.

In another aspect, the invention features wave soldering systems. The systems include a separating vessel configured to receive and support molten solder, a gas injection circuit arranged to inject one or more gases into molten solder disposed within the separating vessel, a soldering vessel, an inlet configured to deliver a flow of molten solder from the soldering vessel to the separating vessel for removal of dross from the molten solder, and an outlet configured to deliver a flow of molten solder from the separating vessel to the soldering vessel.

In some implementations, the gas injection circuit includes a gas source, and one or more gas injection pipes in fluid communication with the gas source and at least partially disposed within the separating vessel. The one or more gas injection pipes can be arranged to deliver a gas from the gas source into the separating vessel. In some cases, the one or more gas injection pipes are at least partially disposed within the separating vessel in a position below a surface level of molten solder disposed within the separating vessel.

In another aspect, the invention features methods of separating dross floating on solder into solder and residue. The methods include delivering molten solder including dross into a first vessel, and injecting a gas into the molten solder in the vessel to separate residue from the molten solder.

In some embodiments, injecting the gas into the molten solder includes delivering a gas from a gas source to a gas injection pipe at least partially disposed within the first vessel. In some implementations, injecting the gas into the molten solder includes delivering gas into the first vessel in a region below a surface level of the molten solder. In some embodiments, injecting the gas into the molten solder comprises delivering nitrogen gas from a gas source into the first vessel. In some implementations, the methods can also include cutting through dross carried by the molten solder.

In some embodiments, the methods can include delivering the molten solder with the residue removed therefrom from the first vessel to a second vessel. Delivering molten solder into the separating vessel can include delivering molten solder including dross from the first vessel into the second vessel.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.

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