Metal fusion bonding – With means to remove – compact – or shape applied flux or filler – By fluid blast or suction
Reexamination Certificate
2000-02-22
2001-05-29
Ryan, Patrick (Department: 1725)
Metal fusion bonding
With means to remove, compact, or shape applied flux or filler
By fluid blast or suction
C228S019000, C219S227000
Reexamination Certificate
active
06237831
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to solder extracting type desoldering tools, and in particular, to such desoldering tools in which the extracted solder is collected in a disposable capsule.
2. Description of Related Art
In solder extracting type desoldering tools, a vacuum is used to draw the re-melted solder into the desoldering tool where it is collected in a solder collecting receptacle of one type or another. While, in some cases, a removable porous solder retention pad, liner or baffle has been provided to retain the collected solder in the collecting receptacle and/or to facilitate removal of the collected solder. An example of one such type of desoldering tool is described in U.S. Pat. Nos. 5,143,272 and 5,007,574 in which a tray like receptacle is a removable, but permanent, part of the tool and in which a removable porous solder retention pad is disposed. Among the short-comings of such desoldering tools are the facts that the tool can only be used in certain orientations and during use the suction flow path can become obstructed with solder and flux, thereby causing the suction force to fall off and the ability of the tool to extract solder is impaired as a result.
Substantially contemporaneous with the present invention, a desoldering tool was introduced by Weller under Model No. SCD-100 in which solder is collected in a disposable cylindrical capsule which is open at one end for receiving the extracted molten solder and is closed at the opposite end by a filter through which the solder extracting vacuum is drawn. To prevent the filter from immediately becoming obstructed by the extracted solder, a metal baffle is disposed within the capsule chamber for the purpose of causing the extracted to solder to solidify thereon. However, in practice, the baffle cannot predictably insure that the intended amount of solder is extracted before a vacuum failure occurs, i.e., sometimes the capsule is able to sufficiently fill with solder and other times vacuum failure might occur well before the capsule is adequately filled with extracted solder. Furthermore, the use of such baffles reduces the effective volume of the capsule to such an extent that a low volumetric efficiency is obtainable even under the best of circumstances, thereby causing the rise time (i.e., the time to reduce the pressure sufficiently to draw the solder up into the tool) to be longer than is optimally desirable. Additionally, since the capsule body is formed of the plastic material Kapton® (which has a usable temperature range of up to 800° F.) and the baffle is made of a metal, such as stainless steel (with a melting point of around 2000° F.), recycling of the extracted solder is not practical since it cannot be easily removed from the capsule, and the capsule and baffle cannot be burnt off at sufficiently low temperatures. Still further, exchanging of a filled capsule with new, empty one is not a simple process that can be performed quickly (which is essential in production facilities) since the capsule is hot, all of the extracted solder may not have solidified, and withdrawal of the capsule requires significant manipulation of the desoldering tool and the capsule itself.
SUMMARY OF THE INVENTION
In view of the foregoing, it is a primary object of the present invention to provide a solder collecting capsule for an extraction type desoldering tool which has a high volumetric efficiency and predictably insures that the intended amount of solder is extracted before a vacuum failure occurs, i.e., failure does not occur until the capsule has reached its intended capacity.
It is another object of the present invention to provide a solder collecting capsule for an extraction type desoldering tool which facilities recovery and recycling of the extracted solder.
Still another object of the present invention is to create a solder collecting capsule and extraction type desoldering tool for use therewith which will enable exchanging of a filled capsule with a new, empty one simply and quickly.
Yet another object of the present invention is to devise a solder collecting capsule and extraction type desoldering tool for use therewith which are constructed such that the desoldering tool will not be able to draw molten solder into it if the tool is inadvertently operated without a solder collecting capsule in place or with the solder collecting capsule inserted backwards.
A further object of the invention is provide a solder collecting capsule and extraction type desoldering tool for use therewith which are designed to shield the vacuum seal from contact with the molten solder being extracted as well as to insure that the molten solder extracted into the capsule will not flow back into the riser tube of the tool.
The first of these objects is obtained in accordance with preferred embodiments of the invention the creation of a capsule having a defined solder receiving space and separate gas extraction flow paths that are constructed, on the one hand, allow the use of a smaller capsule for receiving a given quantity of solder, thereby reducing rise time, and on the other hand, insures that vacuum failure does not occur until the solder receiving space is full.
The second of these objects is obtained by the solder receiving capsule being made entirely of materials that can be burnt off at sufficiently low temperatures, e.g., less than about 500° F.
The third of these objects is achieved by constructing the solder receiving capsule and its holding structure within the desoldering tool so that a new solder receiving capsule itself can be used to push out the full one as it is installed.
The fourth and fifth objects are achieved by a special configuring of vacuum seal and the end of the capsule intended to seal thereagainst together with use of an riser tube of proper length.
These and other objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawings which, for purpose of illustration only, show several embodiments in accordance with the present invention.
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Gilbert David Lee
Lawrence David W.
Le Dung T.
Siegel William Jordan
Johnson Jonathan
Nixon & Peabody LLP
Pace Incorporated
Ryan Patrick
Safran David S.
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