DROSS REMOVAL APPARATUS FOR SOLDERING MACHINE AND

METHOD THEREOF

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a dross removal apparatus and method to transfer and collect dross or oxidized solder to a collection chamber of a soldering machine therefrom, comprising front declination plate, hingable declination back plate, channels receiving solder from said declinations, and a collection chamber having a corresponding top cover for manual scooping of dross at surface layer.

BACKGROUND OF THE INVENTION

Dross is formed during an oxidisation reaction between solder against atmosphere. Dross is also formed through chemical reaction between solder against of solder flux which is pre-cursor agent to aid soldering of printed circuit boards or the like. Dross can be in powder or flaky form, without proper removal or disposal method could lead to printed circuit board solder defects and its production efficiency. Numerous prior arts of dross removal of soldering machine are known, which are very complicated with the use of big and bulky apparatus to remove dross from solder. Users in the past needs to either open up the cover of the soldering machine to remove the dross from the solder reservoir, leading to nitrogen gas leakages, which in turn creates more dross. At times, the process of removing the dross from the solder reservoir can also interfere with the soldering process, thus creating slower soldering process. The prior art also comprises of only one layer of cover, which does not contain nitrogen gas that effectively, which in turn creates more dross.

In order to alleviate these shortcomings, the present invention provides a dross removal apparatus to transfer and collect dross or oxidized solder to a collection chamber of a soldering machine therefrom, comprising front declination, rear hingable declination, channels receiving solder from said declinations, and a collection chamber such that the components are simple and the user will not need to interfere with the soldering process in order to remove dross from the solder reservoir.

SUMMARY OF THE INVENTION

Accordingly, it is the primary aim of the present invention to provide a system or a plurality of devices to remove dross from soldering fountain. It is an object of the present invention to provide a simple and efficient dross removal method by collecting dross from dross channel without affecting the soldering process.

Additional objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in actual practice.

According to the preferred embodiment of the present invention the following is provided:

A dross removal (1) of a continuous soldering machine, comprising: at least one molten solder pumping means (14); at least one soldering fountain (19); at least one stationary front declination plate (11) preferably coupled longitudinally in front of said soldering fountain (19); at least one declination back plate (12); characterized in that said dross removal (1) further comprising of at least one dross collection chamber (13) having a corresponding top cover for manual scooping of dross at the surface layer, wherein said dross collection chamber (13) is placed away from the solder fountain (19) and still placed on top of the dross reservoir (42), wherein said dross collection chamber (13) is bottomless to allow solder to flow back to the dross reservoir (42); at least one dross dropping channel (15) located beneath said stationary front declination plate (11) further extended to a dross intersection channel (18) before further extended to said dross collection chamber (13); at least one dross dropping channel (17) located beneath said stationary declined back plate (12) further extended to another dross intersection channel (16) before meeting said dross intersection channel (18) before further extended to said dross collection chamber (13); said dross dropping channels (15, 17) and dross intersection channels (16, 18) are with downward slope towards said dross collection chamber (13); said declined back plate (12) is preferably coupled longitudinally behind said solder fountain (19), which is hingeable enabling to swing upward or downward. ond embodiment of the present invention, there is provided, A method of dross removal from a continuous soldering machine, comprising the steps of: i) at least one molten solder pumping means (14) pumping molten solder towards at least one soldering fountain (19); characterized in that said method further comprises of the following steps after step i); ii) solder and dross flowing from said soldering fountain (19) to at least one dross dropping channel (15) through at least one stationary front declination plate (11); and flowing to at least one dross dropping channel (17) through at least one declination back plate (12); iii) solder and dross flowing along the downward slope of said dross dropping channels (15, 17) to the dross collection chamber (13) through the downward slope of dross intersection channels (16, 18); iv) dross floating at the surface of the dross collection chamber (13) while the heavier solder flowing back to the solder reservoir (42) so that users can manually scoop up dross from said dross collection chamber; v) steps i to iv are repeated.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Other aspect of the present invention and their advantages will be discerned after studying the Detailed Description in conjunction with the accompanying drawings in which:

FIG. 1-A illustrates the top view of the present invention with both channels cover installed.

FIG. 1-B illustrates the top view of the present invention without both channels cover installed.

FIG. 2-A shows a perspective front view of the present invention with channels cover installed.

FIG. 2-B shows a perspective front view of the present invention with channels cover unins tailed.

FIG. 3-A and 3-B show the perspective view and close up view of the rotary shaft, while FIG 3-C shows the front view of said rotary shaft. FIG. 4-A and 4-B displays the front and back view of the present invention showing the solder and dross travel path of the dross removal apparatus and the soldering machine.

FIG. 5-A displays the present invention with first layer of cover installed.

FIG. 5-B displays the detailed perspective view of the first layer of cover.

FIG. 5-C displays second layer of cover installed above of the first layer of cover.

FIG. 5-D displays the side view of the present invention showing the curtains.

FIG. 6-A & 6-B display side view of the front declination, dross channel, and back plate, with the back plate in declined and horizontal position respectively.

FIG. 7 displays the perspective view of another embodiment of the present invention with extended mid assembly and exemplary second layer cover.

DETAILED DESCRIPTION OF THE DRAWINGS In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by the person having ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and/or components have not been described in detail so as not to obscure the invention.

The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings, which are not drawn to scale.

Referring to FIG. 1-A and 1-B, they display the top view of the present invention of dross removal apparatus coupled to a soldering machine (1) with the cover (20, 21) installed and removed respectively. The dross removal apparatus coupled to a continuous soldering machine (1) comprises of at least one dross collection chamber (13), at least one molten solder pumping means (14) and at least one soldering fountain (19); further comprises of at least one stationary front declination plate (11) preferably coupled longitudinally in front of said soldering fountain (19), at least one declined back plate (12) preferably coupled longitudinally behind said solder fountain (19), which is hingeable enabling to swing upward or downward, at least one dross dropping channel (15,) located beneath said stationary front declination plate (11) further extended to a dross intersection channel (18) before further extended to said dross collection chamber (13); and at least one dross dropping channel (17) located beneath said declined back plate (12) further extended to another dross intersection channel (16) before meeting said dross intersection channel (18) before further extended to said dross collection chamber (13); whereby said dross dropping channels (15, 17) and dross intersection channels (16, 18) are having downward slope towards said dross collection chamber (13).

As shown in FIG 1-A and 1-B, at least one printed circuit board (PCB) (28) is conveyed in the direction of the dotted arrow, passing said solder fountain (19) so that the molten solder exiting from said solder fountain (19) is able to be applied to the bottom surface of the PCB (28).

The said dross removal of the soldering machine (1) further comprises of at least one rotary shaft (101) placed at the top surface of the solder fountain (19) along said solder fountain (19) so that when said rotary shaft (101) is rotated, a rippled / turbulence solder surface effect is created to increase the level of application of solder to said PCB (28).

FIG 2-A and 2-B show the perspective front view of the present invention with channels cover installed and uninstalled respectively. As molten solder exits from the solder fountain (19), majority of the solder flows over said front declination plate (11). The front declination plate (11) is disposed longitudinally of the solder fountain (19); the plate (11) is stationary, and can have curvature on the surface. A small portion of solder flows over an declined back plate (12). Both plates (11, 12) abut a dross channel, namely front dross channel (15) for front plate (11); and back dross channel (17) for back plate (12). The solder which contains dross converges in an intersection channel (18) from front channel (15) and back channel (17). Alternatively, the back channel (17) goes through an intersection channel (16) on the lateral side of the fountain (19) before being approaching said intersection channel (18). The intersection channel (18) then directs the solder to a dross collection chamber (13). The front dross channel (15), back channel (17) and intersection channel (16) is preferably declined towards the chamber (13) to ease the solder flow. In another embodiment, intersection channel cover (20) and side dross channel cover (21) can be mounted on respective dross channels for better protection against nearby system components. The front channel (15) is typically larger than the back channel (17) because more solder will be flowing to the front channel due to the movement of the PCB. The advantages of having the dross dropping channels (15, 17) and dross intersection channels (16, 18) is that with the declination nature of the channels, the dross will be channeled to the dross collection chamber (13) quicker than usual, thus having less contact with new solder from the solder fountain (19), thus reducing the amount of new dross. The dross collection chamber (13) is having a corresponding top cover for manual scooping of dross at the surface layer, wherein said dross collection chamber (13) is placed away from the solder fountain (19) and still placed on top of the dross reservoir (42), wherein said dross collection chamber (13) is bottomless to allow solder to flow back to the dross reservoir (42). The dross collection chamber (13) is such that it does not have any physical or chemical separating mechanism to separate the existing dross from the molten solder, but rather using the physical nature of the difference in weight between the existing dross and solder whereby the lighter dross will float at the surface of the dross collection chamber and the heavier solder will flow down back to the solder reservoir.

The rotary shaft (101) optionally comprises of at least one bush and bearing / bush pair (26) to act as rotary movement connector between the rotary actuator to the rotary shaft (101). Since the rotary shaft (101) is placed along the solder mountain (19) and cuts through the lateral wall to extend towards the rotary actuator, the bush is placed at the outer side of the lateral wall while the bearing / bush is placed at the inner side of the lateral wall. This bush and bearing / bush pair is as rotary movement connector between at least one rotary actuator to the rotary shaft (101) while preventing leaking of solder from the solder fountain (19) from the lateral wall. Preferably, the material used for the outer bush is bronze or graphite while the material used for bearing / inner bush is graphite. Graphite is used for the bearing / inner bush because solder will etch metal. It is to be understood that other metal materials can be used for the outer bush and other non-metal materials can be used for the bearing / inner bush.

As shown in FIG 3- A, 3-B and 3-C, which are close up views of the rotary shaft (101), the rotary shaft (101) is with at least one flat cut off surface along a portion of said rotary shaft (101) so that when the rotary shaft (101) is rotated, this flat surface will create turbulence to the surface of the solder fountain (19).

As shown further in FIG 2-A and 2-B, an alternative to installing the rotary shaft (101) is to have said dross removal apparatus of the soldering machine (1) to optionally comprise at least one vibration means (27) connected to said dross removal apparatus near the surface of the solder fountain (19) to create vibration to said dross removal apparatus (1). When said PCB (28) is conveyed through the solder fountain (19), solder will enter the via hole at the bottom surface of the PCB (28) more effectively with this vibration or ripple effect created by said vibration means (27). Preferably, the vibration means (27) may comprise of at least one vibration transfer means such as a rod connecting between at least one vibrator to said dross removal apparatus. However, other forms of vibration means (27) is also applicable as long as it is able to create vibration to the dross removal apparatus (1), thus creating a ripple effect to the solder surface of the solder fountain (19). As shown in FIG 1-A, 1-B, 2- A, 2-B and further substantiated by FIG 4- A, at least one dross collection chamber (13) is created for the present invention, which placed away from the solder fountain (19). It is placed away from the chamber which governs the solder fountain (19) in order to ease the user get access to the collection chamber (13) without removing the cover for solder fountain (19) and without creating leakage of nitrogen gas supplied to said chamber. As shown in the figures, once the molten solder gushes out from the solder fountain (19) caused by the molten solder pumping means (14), the molten solder and dross will then flow from said soldering fountain (19) to at least one dross dropping channel (15) through at least one stationary front declination plate (11) and flowing to at least one dross dropping channel (17) through at least one declined back plate (12). The solder and dross will then flow along the downward slope of said dross dropping channels (15, 17) to the dross collection chamber (13) through the downward slope of dross intersection channels (16, 18). The dross collection chamber (13) is usually away from the chamber encompassing the solder mountain (19). The dross collection chamber (13) comprises of a bottomless container with a matching cover. When the molten solder and dross reaches the dross collection chamber, the heavier solder will flow downwards towards the solder reservoir (42) since the dross collection chamber (13) is bottomless. However, the level of solder is always covering at least most (usually but not always half inch from surface of dross collection chamber (13)) of the dross collection chamber (13) and dross dropping channels (15, 17). Therefore, the lighter dross will always be floating at the dross collection chamber (13) so that the users can manually scoop up dross from said dross collection chamber (13). Since the location of the dross collection chamber (13) is away from the solder mountain (19), the user needs to only open up the cover of the dross collection chamber (13) and scoop out the dross collected at the surface of the solder from the dross collection chamber. A very important point here is that the user does not need to interfere with the operations of the solder fountain (19) and the soldering process while removing dross from the soldering station, which in the past has a big problem of nitrogen gas leakage and inconvenient in doing so. The function of the cover on top of the dross collection chamber (13) is to contain the nitrogen gas available in the said chamber (13). This is because nitrogen gas is freely flowing inside the chambers of the solder fountain, along the dross dropping channels (15, 17) and dross intersection channels (16, 18) and also to the dross collection chamber (13) because nitrogen will prevent more dross from being developed. A handle is available at the cover of the dross collection chamber (13) to ease the removal of the cover by the user. The dross collection chamber (13) further comprises of at least one tube to infuse nitrogen gas into the dross collection chamber and solder reservoir (42). FIG 4- A and 4-B displays the front and back view of the present invention showing the solder and dross travel path (dotted arrows) of the dross removal apparatus and the soldering machine. During an activation of a solder pump (14), a prime mover of molten solder, the solder is pumped from the reservoir (42) to beneath a solder fountain (19) through a flow duct (40). The solder then travels through a plurality of vane elements or fish bone structures (not shown) disposed in the internal of the solder fountain (19). Different depths of vane elements assures of same level of molten solder on the fountain (19) surface during the soldering of a PCB. The furthermost part of the fountain (19) from the pump (14) has the deepest vane element, while conversely, the nearest part of the fountain (19) from the pump (14) has the shallowest vane element. This will enable the force created by the gush of solders pumped from the solder reservoir (42) to be levelled up at the molten solder of the solder fountain (19). After the solder is gushed out from the solder fountain (19), it flows down to the dropping channel (15, 17) towards the dross intersection channel (16, 18) before reaching the dross collection chamber (13). Since the dross collection chamber (13) is bottomless, the solder will flow downwards back to the solder reservoir (42) to be pumped back up again. The above process is repeated until the soldering process if completed. Referring to FIG. 5-A, in this embodiment the solder pump (14) is coupled with any suitable actuator such as an electric motor (29), preferably with pillow block bearing for ease of maintenance. In conjunction with FIG 1-A and 1-B, the pump (14) can be of any suitable pump, whereby the solder is pumped up through the smaller diameter to the flow duct (40). This figure also shows the solder reservoir (42) which contains the dross removal apparatus whereby the solder level will usually but not confined to half inch from the surface of the apparatus.

Referring to FIG. 5-B shows an exemplary first layer cover (60) with frame structure to support a plurality of inert gas tubes (70) disposed near the cover (60). The inert gas tubes (70) induce nitrogen gas to where the solder is mostly available. The cover (60) is placed and concealed over the soldering fountain (19), front plate (11), back plate (12), dross channels (15, 16, 17, 18), dross channel cover (20, 21); the cover (60) is preferably removable from the dross removal system (1). The said first layer cover (60) further comprises of at least one layer of curtain (604, 605, 606) protruding upwards from preferably all four edges of the first layer cover (60). Examples are curtains protruding upwards are side curtains (604), front curtain (605) and back curtain (606). Preferably, there are also airtains covering all possible small openings of the first layer cover (60) to trap Nitrogen gas inside said cover (60). Referring to FIG. 5-C shows an exemplary second layer cover (62) of the system (1). The cover (62) surface comprises at least one handle bar (601, 602) and at least one aperture (603) fitted with thermal resistance sight glass or polyplastic to enable user for visual inspection. The sight glass is preferably capable to withstand high temperature and chemically resistant towards fume particles. The sight glass (603) can be opened by the user without opening the second layer cover (62) by handling one of the handle bar (601) located at one side of the sight glass (603) and said sight glass (603) having hinges (604) at the opposite side. Typically the purpose of opening the sight glass (603) without opening the second layer cover (62) is for fine tuning of the solder apparatus, lead clearance or for checking the solder level. Other handles (602) are also available at the second layer cover (62), optimally one at each opposing side of the second layer cover (62) for the user to open the second layer cover (62).

As shown further in FIG 5-D, to further improve containment of nitrogen gas, the cover (62, 63) further comprises a plurality of curtains protruding downwards from the front (601), back (602, 610) and side (603) of the cover edges, prior to the PCB (28) being fed and after the PCB exits the system (1). The PCB travel path is indicated by dash arrow in FIG 5-C. A mid assembly (64) is a side wall covering the side and exit portion of the cover (62). The mid assembly (64) comprises of curtains protruding downwards towards and touching the side (607) and exit (608) edges of the dross reservoir (42). The curtains (601, 602) of the second layer cover (62) touch the curtains (606, 608, 609) of the first layer cover (60), dross reservoir (42) and mid assembly (64, 65) so that all will contain the nitrogen gas. The dross reservoir (42) also has curtain at the front side (609) protruding upwards. If a PCB is fed to the soldering machine, it will push away the front curtains of first layer cover (60) and second layer cover (62) and the curtains will be in the initial closed position once the PCB passes the front edge of the covers. This action is repeated when the PCB reaches the back cover edge as well.

Referring to FIG. 6-A and 6-B, it show that the back plate (12) can be declined to a certain upward angle or to be horizontal by having the user to turn the turning knob (25) which is extended outwardly from mid assembly (64) of the dross removal apparatus (1) so that the user can control the declination of the back plate (12) without disturbing the soldering process. The user needs to adjust the declination of the back plate (12) in order to control (increase or reduce) the back flow to optimize the soldering process. FIG 6-A and 6-B also show the location of the outer bush and bearing / inner bush (26) placed at the lateral wall of said solder fountain (19). The dotted arrow shows the flow of the solder and dross from the solder fountain (19) towards the front channel (15) through the front plate (11) and towards the back channel (17) through the back plate (12). FIG 7 displays the perspective view of another embodiment of the present invention with extended mid assembly (65) and extension (63) for second layer cover (62). The second layer cover extension (63) and extended mid assembly (65) extends from the back edge of the second layer cover (62) and mid assembly (64) respectively. The second layer cover extension (63) further comprises of curtains (610) downwardly protrading from the front and back edge of the said extension (63), touching curtains (611) upwardly protruding from extended mid assembly (65) to contain nitrogen. The extended mid assembly (65) and extended second layer cover (63) is for the purpose of further containing the nitrogen gas from the chamber, when PCB goes through the said chamber.

While the present invention has been explained and described with preferred embodiments thereof, it will be understood by those skilled in the art that numerous modifications and changes, and sequence in the flow method may be made without departing from the scope of the present invention. Therefore it is intended by the appended claims to cover all such modification and changes of the present invention.