Patent Publication Number: US-6342146-B1

Title: Lead-free alloy plating method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 08/679,734, entitled “Continuous Rack Plater,” filed Jul. 12, 1996, now U.S. Pat. No. 5,985,106 which claims priority to U.S. Ser. No. 60/001,171 filed Jul. 14, 1995, the specification of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention (Technical Field) 
     The present invention relates to a plater which continuously plates articles. The invention is suitable for single substance or alloy plating. The invention further provides novel rinse and dryer methods and devices. 
     2. Background Art 
     There are numerous continuous platers in the prior art. For instance, U.S. Pat. No. 2,142,829, entitled “Plating Machine” to J. F. Trudeau; U.S. Pat. No. 2,255,922, entitled “Return Type Fast Transfer Machine” to V. Finston; U.S. Pat. No. 2,428,141, entitled “Process for Cleaning, Stripping, and Polishing Metal Surfaces” to T. E. Burkhardt; U.S. Pat. No. 2,387,160, entitled “Article Handling Apparatus” to W. W. Loney; U.S. Pat. No. 4,189,360, entitled “Process for Continuous Anodizing of Aluminum” to Woods, et al.; U.S. Pat. No. 4,263,122, entitled “Electrocoating Equipment” to Urquhart; and Meaker Variable Speed Plating Machine pamphlet; all disclose a single bath continuous plating system. However, these references do not disclose multiple baths. In addition, the &#39;122, &#39;360 and &#39;141 patents do not teach a horizontal system, but lower and lift articles or parts to be plated into the bath. The &#39;160 patent describes plating only a portion of the article, leaving the rest above the plating bath. U.S. Pat. No. 2,043,698, entitled “Method and Apparatus for Spacing Electrodes” to J. P. Dyer discloses spacing anodes for a plating operation. 
     Other prior art patents disclose multiple plating baths or processes, such as U.S. Pat. No. 3,266,308, entitled “Electrochemical Treating and Apparatus” to H. Pochapsky, et al.; U.S. Pat. No. 3,657,097, entitled “Selective Plating Machines” to Baldock, et al.; U.S. Pat. No. 4,377,461, entitled “Tab Plater for Circuit Boards or the Like” to Lovejoy; U.S. Pat. No. 4,501,650, entitled “Workpiece Clamp Assembly for Electrolytic Plating Machine” to Maron; U.S. Pat. No. 4,539,090, entitled “Continuous Electroplating Device” to Francis; and U.S. Pat. No. 4,812,211, entitled “Process and System for Electrodeposition Coating” to Sakai. The &#39;211 and &#39;309 patents disclose complicated movement systems; the &#39;211 patent provides for the articles to be plated to be disposed in baskets. The &#39;211, &#39;090, &#39;650, &#39;097 and &#39;461 patents all disclose chain conveyor systems, some with hoists for lowering and lifting the parts into the baths/processes. The &#39;090, &#39;650, &#39;097, and &#39;461 patents all disclose plating only a portion of the article, rather than submerging the entire article into the plating tank. 
     The present invention, on the other hand, allows for multiple bath plating, alloy plating, submersion of the entire article, a novel horizontal conveyor/drive system and recycling of most process streams. 
     SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION) 
     The present invention is of a continuous plating system and method for plating articles comprising: multiple baths, wherein at least one bath comprises a plating bath; a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor comprising altemating links and hinges, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. In describing the present invention, the words “bath” and “station” are interchangeable, for example, a rinse station is equivalent to a rinse bath and a drying station is equivalent to a drying bath. In the preferred embodiment, the links comprise feet to be driven by the drive and the feet provide electrical current continuity between the conductor and the carriers. A preferred support bar for the conveyor is made of a synthetic resin polymer (e.g., Teflon), and the conveyor and the carriers are preferably (silver) plated to provide electrical conductivity. The plating bath comprises at least one anode for plating the anode substance onto the articles, an upper tank disposed within a lower tank for providing overflow and recirculation of a plating solution, a narrow opening and a narrow exit corresponding substantially in shape and width to the articles (and preferably comprising adjustments for changing the shape and size of the opening and exit), multiple pumps for providing even plating conditions to the articles, and multiple spray jets for providing even circulation and plating to the articles. Internal guides are best used within at least one of the multiple baths for preventing sway of the articles and external guides external to at least one of the multiple baths for providing ease of movement of the articles into the bath. The articles may be flat or non-planar. The carriers preferably have hooks which hook into an opening in the articles. The system preferably has an oval configuration and applies additional direct current by exposed cable or brushes. The system best further comprises a dryer in line with the continuous plating system and positioned after the multiple baths, the dryer comprising: a box comprising a heated fluid; an entry opening for the articles to enter the box; and an exit opening for the articles to exit the box, as well as a wicking device (such as a mesh material in the box) to help remove moisture from the articles. The system also best employs a rinse system in line with the continuous plating system and positioned after the multiple baths, the rinse system comprising: a first rinse station wherein a substance from the multiple baths is rinsed from the articles, the first rinse station comprising an effluent with a higher concentration of the substance; and at least one additional rinse station wherein the substance Is further rinsed from the articles, the additional rinse station comprising an effluent with a lower concentration of the substance; and for recycling effluent from the rinse station back into the continuous plating system (preferably with at least four rinse stations). The articles are preferably completely submerged within the plating bath(s). Most preferably, the plating system comprises: at least three plating baths, wherein the first bath comprises a substance to be plated on the articles, the second bath comprises a different substance to be plated on the articles and the third bath comprises the same substance as the first bath to be plated on the articles, the substances comprising an alloy plate (preferably tin and bismuth) on the articles; a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. Most preferably, the system uses at least five plating baths in the following order and comprising the following in solution to be plated on the articles: fin, bismuth, tin, bismuth and tin. However, the system can be used to plate many metal alloys, including tin, bismuth, lead, titanium, cadmium, nickel, and zinc, and combinations thereof. Further, the system preferably has at least one bath comprises a plating bath, and the other baths comprise at least one process bath selected from the group consisting of cleaning, electrocleaning, degreasing, rinsing, drying, fluxing, reflowing and stripping, most preferably at least the following baths in the following order a cleaning bath; a rinsing bath; a plating bath; and a rinsing bath, preferably with a drying station subsequent to the final rinsing bath. The conveyor may comprise the conductor, so as to provide electricity to the articles while being conveyed thereon. Here, synthetic resin polymer bars (e.g., Teflon) may be used to support the conveyor. 
     The invention Is also of a continuous plating system and method for plating articles comprising: multiple baths, wherein at least one bath comprises a plating bath; a horizontal continuous conveyor system for passing the articles through the multiple baths while completely submerging the articles in the multiple baths, comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. At least one of the multiple baths should comprise a stripping bath positioned after the plating bath for stripping the carriers of a substance plated on the carriers in the plating bath. 
     The invention is also of a continuous plating system and method for plating articles comprising: multiple baths, wherein at least one bath comprises a plating bath, and the other baths comprise at least one process bath selected from the group consisting of cleaning, electrocleaning, degreasing, rinsing, drying, fluxing, reflowing and stripping; a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. In the preferred embodiment, at least the following baths in the following order are employed: a cleaning bath; a rinsing bath; a plating bath; and a rinsing bath, and preferably a drying station subsequent to the final rinsing bath. 
     The invention is additionally of a continuous plating system and method for alloy plating of articles comprising: at least three plating baths, wherein the first bath comprises a substance to be plated on the articles, the second bath comprises a different substance to be plated on the articles and the third bath comprises the same substance as the first bath to be plated on the articles, the substances comprising an alloy plate on the articles; a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. The system best further comprises a dryer in line with the continuous plating system and positioned after the multiple baths, the dryer comprising: a box comprising a heated fluid; an entry opening for the articles to enter the box; and an exit opening for the articles to exit the box, as well as a wicking device (such as a mesh material in the box) to help remove moisture from the articles. The system also best employs a rinse system in line with the continuous plating system and positioned after the multiple baths, the rinse system comprising: a first rinse station wherein a substance from the multiple baths is rinsed from the articles, the first rinse station comprising an effluent with a higher concentration of the substance; and at least one additional rinse station wherein the substance is further rinsed from the articles, the additional rinse station comprising an effluent with a lower concentration of the substance; and for recycling effluent from the rinse station back into the continuous plating system (preferably with at least four rinse stations). The articles are preferably completely submerged within the plating bath(s). Most preferably, the plating system comprises: at least three plating baths, wherein the first bath comprises a substance to be plated on the articles, the second bath comprises a different substance to be plated on the articles and the third bath comprises the same substance as the first bath to be plated on the articles, the substances comprising an alloy plate (preferably tin and bismuth) on the articles; a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed. Most preferably, the system uses at least five plating baths in the following order and comprising the following in solution to be plated on the articles: tin, bismuth, tin, bismuth and tin. However, the system can be used to plate many metal alloys, including tin, bismuth, lead, titanium, cadmium, nickel, and zinc, and combinations thereof. Further, the system preferably has at least one bath comprising a plating bath, and the other baths comprise at least one process bath selected from the group consisting of cleaning, electrocleaning, degreasing, rinsing, drying, fluxing, reflowing and stripping, most preferably at least the following baths in the following order a cleaning bath; a rinsing bath; a plating bath; and a rinsing bath, preferably with a drying station subsequent to the final rinsing bath. The conveyor may comprise the conductor, so as to provide electricity to the articles while being conveyed thereon. Here, synthetic resin polymer bars (e.g., Teflon) may be used to support the conveyor. 
     The invention is still further of a continuous plating system and method for plating articles comprising: multiple baths, wherein at least one bath comprises a plating bath; and a continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor comprising a conductor for providing electricity to the articles while being conveyed, and numerous carriers for attaching numerous articles to the conveyor. The preferred embodiment preferably comprises synthetic resin polymer bars (e.g., Teflon) to support the conveyor when no direct current is present. 
     The invention is yet further of a continuous plating system and method for plating articles comprising multiple baths, wherein at least one bath comprises a plating bath; a horizontal continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor, and a conductor for providing electricity to the articles while being conveyed; the invention further comprising: a dryer in line with the continuous plating system and positioned after the multiple baths, the dryer comprising: a box comprising a heated fluid; an entry opening for the articles to enter the box; and an exit opening for the articles to exit the box. The preferred embodiment includes a wicking device for wicking moisture from the articles, such as a mesh material disposed in the box (preferably at the bottom), and internal guides for stabilizing the articles within the box. 
     The invention is additionally of a continuous plating system and method for plating articles comprising multiple baths, wherein at least one bath comprises a plating bath; a horizontal continuous conveyor system for passing the articles through the multiple baths comprising a drive, a conveyor, and numerous carriers for attaching numerous articles to the conveyor; and a conductor for providing electricity to the articles while being conveyed; the invention further comprising: a rinse system in line with the continuous plating system and positioned after the multiple baths, the rinse system comprising: a first rinse station wherein a substance from the multiple baths is rinsed from the articles, the first rinse station comprising an effluent with a higher concentration of the substance; and at least one additional rinse station wherein the substance is further rinsed from the articles, the additional rinse station comprising an effluent with a lower concentration of the substance; and for recycling effluent from the rinse station back into the continuous plating system. Preferably, the improvement employs at least four rinse stations. 
     A primary object of the present invention is to provide a continuous, multiple bath plating system, capable of single substance or alloy plating. 
     Another object of the present invention is to provide a continuous plating system which allows for submersion of the entire article into each bath. 
     Yet another object of the present invention is to provide for a continuous, horizontal conveyor system, which utilizes links and hinges. 
     Another object of the present invention is to provide recycling of most process streams. 
     A primary advantage of the present invention is that numerous articles can be plated in a short time frame, in an efficient and low cost manner. 
     Another advantage of the present invention is that alloy plating can be provided, including homogeneous alloys. 
     Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings: 
     FIG. 1 is a perspective view of the continuous rack plater of the present invention; 
     FIG. 2 is a top flowchart view of the preferred embodiment of the invention of FIG. 1; 
     FIG. 3 is a side view of the preferred hook and rail configuration of the invention of FIG. 1; 
     FIG. 4 is a cutaway end view of the preferred hook and rail configuration of the invention of FIG. 1; 
     FIG. 5 is a pulley assembly configuration of the invention of FIG. 1; 
     FIG. 6 is a cutaway end view of the preferred tank entry configuration of the invention of FIG. 1 for flat parts to be plated; 
     FIG. 7 is a cutaway end view of an alternative tank entry configuration of the invention of FIG. 1 for angled parts to be plated; 
     FIG. 8 is a top view of the preferred plating tank configuration of the invention of FIG. 1; 
     FIG. 9 is a perspective view of the preferred dryer configuration of the invention of FIG. 1; 
     FIG. 10 is a flowchart view of the preferred rinse configuration of the invention of FIG. 1; 
     FIG. 11 is a flowchart of an alternative embodiment for alloy plating using the invention of FIG. 1; 
     FIG. 12 is a scanning electron photomicrograph of Sn/Bi coating in SEI mode at 700×magnification; 
     FIG. 13 is a scanning electron photomicrograph of Sn/Bi coating in composition mode at 700×magnification; and 
     FIG. 14 is a perspective view of the reflow portion of the invention of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Best Modes for Carrying Out the Invention 
     The present invention relates to a continuous rack plater for continuously plating of flat parts and parts with angles or relief. The invention allows for plating with single or multiple substances. 
     With reference to the drawings, continuous rack plater  10  provides for plating of numerous, multiple parts (e.g., see a flat part  12  shown in FIGS. 6 and 9 and an angled part  86  in FIG.  7 ). The parts  12  to be plated are loaded or otherwise placed  13  on hooks  16  disposed on conveyor belt  18 . The loading  13  and unloading  44  may be accomplished by a human operator or by automatic equipment (not shown) (e.g., a ramp which pushes the parts  12  off). Conveyor belt  18  travels (see FIGS. 2 and 10) around drive pulley  20  on one end and idler pulleys  22 ,  22 ′ and  22 ″. Drive gear  24  powers and drives drive pulley  20  so that conveyor belt  18 , with hooks  16  containing parts  12 , can revolve through various cycles, equipment and processes (preferred embodiments discussed below). The invention is not limited to the particular cycles and processes described herein, as any steps, cycles, processes, solutions, substances to be plated, etc., can be used in accordance with the present invention. The term “plating” as used throughout the specification and claims is intended to include all forms of electrochemical processing such as electroplating, electroforming, electrocoating, electrodeposition, coating, stripping, alloying, and the like. 
     In the first step of the present invention, parts  12  are disposed on conveyor  18 . The hooks  16  shown in the drawings are only one possible means for disposing the parts  12  to be plated on conveyor  18 , and are particularly useful when the parts have a hole therethrough  17 . Different sized hooks can be used for different articles and are easily removed and replaced on the conveyor. Other attachment means, e.g., slots, magnets, wires, strips, holes, etc., may be used for disposing parts  12  to be plated on conveyor  18 . 
     Conveyor belt  18  acts as a conductor for the plating. In the preferred embodiment, continuous rack plater  10  is in an oval configuration so that power lines and piping lines can be more easily provided to the plater  10 . 
     Reference is made to FIG. 2 of the invention which illustrates a typical process embodiment of the invention of FIG.  1 . The arrows show the direction of travel of conveyor  18 . As shown in this flowchart, parts  12  are loaded  13  onto conveyor  18 . If the parts  12  are dirty or oily they can pass through a cleaner or degreaser  26 . A typical degreaser, useful in the present invention, comprises a spray box with nozzles which spray a detergent solution on the parts. The spray nozzles can be made to provide turbulent flow (e.g., using a narrow nozzle) or laminar flow (e.g., using a wide nozzle), depending on the extent of the degreasing  26  necessary and the stability of the parts  12 . The parts  12  are then rinsed  28  (e.g., with spray nozzles) and can then be cleaned again in an electrocleaner  30  (e.g., a standard plater&#39;s detergent solution with anodes or cathodes (e.g., hanging over the edges) for scrubbing hydrogen or oxygen on the surface of the parts  12 ). After electrocleaner  30 , parts  12  are rinsed again  32  (e.g., with spray nozzles). Parts  12  then travel through an acid bath  34  (e.g., typical plater&#39;s acid bath solution) to remove very light oxides (e.g., rust) and neutralize any remaining detergent. Parts  12  are then rinsed  36  again (e.g., with spray nozzles) prior to entering the plating bath  38 . Plating bath  38  contains typical platers solutions for plating substances (e.g., nickel or other metals or alloys) onto parts  12 . After parts  12  exit plating bath  38  they are rinsed  40  (e.g., with spray nozzles) and then dried in dryer  42  (e.g., using hot air). Preferably, parts  12  are subjected to a blower  39  prior to the dryer  42  to remove much of the rinse stream  40 . Parts  12  are then unloaded  44  and are complete. Hooks  16  which are now empty of parts  12  are then stripped  46  (e.g., using typical stripping solutions) and then rinsed  48  prior to being reloaded  13  for plating on continuous rack plater  10 . As can be seen, the number and types of tanks and stations and processes depend entirely on the part to be plated, the thickness and final characteristics desired, the incoming character of the part, etc. For instance, some parts may not require cleaning or rinsing, whereas other parts may required multiple plating steps. The present invention is not limited to the particular processes described herein. 
     With reference to FIGS. 3 and 4, the preferred attachment of hook  16  to conveyor  18  is shown. Conveyor (which acts as a conductor) preferably comprises individual links  50 ,  50 ′ (e.g., made of brass or steel and plated with silver or other conductive and corrosion protection coatings). Hooks  16 ,  16 ′ are preferably attached to links  50 ,  50 ′ via a washer S 2 , screw  54  and nut  56 . Link  50  comprises slots  58 ,  58 ′ and foot  60  to be driven by drive gear  20 . Foot  60  aids travel of link  50  on conductor bar or synthetic resin polymer bar (e.g., Teflon)  62  and provides current continuity between conductor bar  62  and hook  16 . Hinge pin  64  attaches individual links  50 ,  50 ′ to each other to form continuous conveyor  18 , while providing flexibility for turning corners in e.g., an oval configuration. The conveyor link arrangement allows direct motion power transfer from the drive gear and is suitable for most applications. A chain drive (not shown) could be used to help with heavier articles. 
     Drive gear  20  comprises a top gear only (corresponding to top slot  58  (see FIG.  3 )) or a top and bottom gear (corresponding to top and bottom slots  58 ′,  58  (see FIG.  3 )) for heavier loads. Drive gear rotates about a motor driven shaft. A variable speed motor turns the shaft by means of a direct drive or belt and pulleys or chain and sprockets. The drive shaft is attached to the drive gear  20 . Spacers in the drive gear mechanism  20  provide for recesses for foot  60  and screw arrangement  54 . 
     As shown in FIGS. 3 and 4, conveyor  18  travels on conductor bar  62  by aid of link foot  60 . Conductor bar  62  is supported by angle  92  and secured by connector (e.g., screw  94 ). Angle  92  is fasted to inverted angle  96  by a screw/washer/nut arrangement  98 . Inverted angle  96  is secured to structure support  100  by a screw/nut/washer arrangement  102 . Conveyor  18  is given vertical support by outer guide  104  which is attached to inverted angle  96  by a screw/washer/nut arrangement  106 . Interior vertical support is provided by inner guide  108  which is attached to angles  92  and by a screw/washer/nut arrangement  110 . 
     FIG. 5 illustrates, in detail, the pulley arrangement for allowing conveyor  18  to rotate through the system. Idler  22  rotates about shaft  112 . Idler  22  comprises recesses  114 ,  114 ′ for foot  60  and screw arrangement  54 , respectively, on hook  16 . 
     Direct current for plating is passed to parts  12  being plated through hook  16 , link  50 , link foot  60 , conductor bar  62 , cable connector  66 , and conductor bar/cable connector screw  94 . Additional direct current can be supplied to links  50 ,  50 ′ by means of exposed cable (e.g., copper cable) or brushes. Silver plating of the conductor/conveyor bar  18  aids corrosion protection, direct current power transfer, and provides a surface with high lubricity for the conveyor link feet  60 , which are also preferably silver plated. 
     As can be seen, other part attachment devices besides hooks  16  can be utilized in accordance with the present invention. Likewise, hooks  16  or other attachment devices may be attached to conveyor  18  by various means. The present invention is not limited to the particular embodiments shown. 
     Conveyor belt  18  pulls hooks  16  and parts  12  to be plated through slots  72  in the ends of process tanks or boxes  74 , as shown in FIGS. 6 and 7. FIG. 6 shows an embodiment of the invention for flat parts whereas FIG. 7 shows an embodiment of the invention with angled or non-planar parts. Tanks  74  can be for any type of fluid process (e.g., cleaning, degreasing, acid treatment, rinsing, plating, stripping, etc.). The slots  72  need to be wide enough for part  12  to pass through, but narrow enough to keep solutions in tanks  74 . Overflow or solution which exits tanks  74  may go to an outer tank or reservoir tank (e.g., see overflow tank  76  and reservoir tank  78 ). FIG. 6 illustrates a narrow slot  72  for allowing passage of a narrow, flat part  12 . FIG. 7 illustrates an alternate slot  84  for an angled part  86 . Horizontal flaps  88 ,  88 ′, typically on the outside of the tank, allow for horizontal adjustment of the slot  84  around part  86  and vertical flaps  90 ,  90 ′, typically on the inside of the tank allow for vertical adjustment of angled part  86 . As can be seen, slots in tanks or boxes may need to be adjusted for each part to be plated. 
     FIG. 6 illustrates that tanks or boxes  74  may comprise entry/exit guides  116 ,  116 ′ to aid parts  12  from entering and leaving tanks  74 . Additional guides  118  may be placed inside the tanks  74  to prevent parts  12  from swaying due to fluid turbulence or high pressure spray. Guides  116 ,  118  may be made of any material which is resistant to the solution in the tank, such as stainless steel wire, plastic covered wire, plastic chord or plastic framework. 
     FIG. 8 is a top view of the preferred plating tank  38  of the present invention. Anode baskets  82  or anodes which hang over or present at the edges of the plating tank (not shown) may be utilized in accordance with the present invention. As can be appreciated by one skilled in the art, any type of anode configuration may be utilized in accordance with the present invention. Anode baskets  82  may contain chips, slugs, sheets or other anode material being plated. Electrical leads are provided to anode baskets  82 . Mesh (not shown) may be placed over anode baskets  82  to prevent particle contamination of the tank  74 . 
     In the preferred embodiment, smaller tanks (e.g., upper overflow tank  76 ) are disposed within larger tanks (e.g., reservoir tank  78 ) so that tank solutions can be allowed to overflow and recirculate via pumps  80  (FIG.  2 ). Solution jets may be provided to tanks to improve circulation of solutions. Multiple pumps may be provided within individual tanks, particularly in larger tanks such as the plating tank, so that the solution may remain homogeneous and at the same temperature throughout. Tanks  74  are preferably made of a material resistant to the solution contained in the tanks. Acrylic, polypropylene, and steel lined with rubber, are generally suitable for typical metal plating tanks. 
     FIG. 10 shows the preferred rinse arrangement  40  following plating  38 . Rinsing following plating is tripled or quadrupled in order to remove all plating chemicals from the surface of the plated part  12 . After plating  38 , the preferred embodiment for rinsing  40  comprises multiple boxes  126  (e.g., 3-4 boxes). These rinse boxes  126  may be joined to save space. The reservoirs can be placed beneath the nickel tank. The reservoirs for  126 ,  28 ,  32 ,  36 , and  48  can be placed under the dryer. In the preferred embodiment, each rinse box  126  comprises a separate rinse reservoir for evaporation. After plating  38 , the first rinse box  126 ′ may have a high metal concentration, the next box  126 ″ will have a lesser metal concentration, the next box  126 ′″ a lower concentration, and so on, until the last box  126 ′″″ has nearly clean water. Deionized water is preferably used to make up the reservoirs. If the plating bath  38  is heated, such as in nickel plating, the metal laden water from the first reservoir can be used to replace the loss of volume in the plating bath  38  due to evaporation. The water in the second reservoir is then pumped to the first reservoir; the water in the third reservoir is pumped to the second reservoir, and the water emptied from the final reservoir is replaced with more deionized water. This system has been found to eliminate the need for effluent treatment of metal. 
     FIG. 9 shows the preferred convection dryer of the present invention. Wet, plated parts  12  are dried in a countercurrent, hot-air convection dryer  42 . Dryer  42  comprises a box in which the hot air is introduced to the part  12  with or without nozzles. A bottom mesh wicking screen  120  may be utilized to wick away moisture from part  12  by touching the bottom of part  12 , resulting in a spot-free part  12 . Dryer  42  box and/or wick screen  120  may be adjusted upwards or downwards to accommodate the size and shape of the part  12 . Hot air enters dryer  42  through a duct  122  that supplies hot air to the dryer  42 , preferably on two sides of the dryer  42 . Air guides  124  direct the hot air towards the opposite end of the dryer  42 . FIG. 9 also illustrates slot  72  through which hook  16  and part  12  enters dryer  42 . 
     After plated articles  12  have been removed from hooks  16 , pass through a stripping box  46 , where an anodic stripping fluid removes plating built up from the hook tips. This process allows hooks  16  to be used for a longer period of time without maintenance or replacement. A cathode (not shown) in the stripping box  46  is negatively charged, while hook  16  is positively charged. The cathode may sit on the bottom of strip tank  46  and rise up the tank sides, where it is connected cathodically to direct current. 
     In the preferred embodiment of the invention, most fluid streams are recycled or reintroduced into the process stream. The invention utilizes countercurrent rinsing as follows: Fresh rinse water is recirculated after the nickel rinses. This water slowly overflows to the acid rinse and is recirculated there. Next, the water overflows to the electrocleaner rinse, recirculated, overflowed to the degrease rinse, recirculated, overflowed to the hook strip rinse, and recirculated, and finally drained. One water source thereby provides rinsing for five operations. 
     In an alternative embodiment of the invention, shown in FIG. 11, alloy plating is possible using the plater  10  of the present invention. FIG. 11 is one example of numerous types of alloy plating possible, namely tin/bismuth plating. For instance, short lead frame strips used in the integrated circuit industry could be plated in accordance with the alloy method of the present invention. Tin/bismuth is preferable to tin/lead plating due to the inherent environmental problems with lead. Heretofore, it has not been possible to easily and inexpensively plate tin/bismuth in a homogeneous manner. Nor, was it possible due to the voltage differences required to plate tin and bismuth in the same bath. The multiple plate process of the present invention overcomes these problems. FIGS. 12 and 13 illustrate scanning electron photomicrographs of the resulting homogeneous alloy structure of tin/bismuth plating. In FIG. 11, one process for fin/bismuth or other alloy plating (such as tin/lead plating, titanium/cadmium, tin/nickel, and tin/zinc) is as follows, many of which steps are similar or the same and described above in reference to FIG.  2 : load parts  13 ; degrease  26 ; rinse  28 ; clean  30 ; rinse  32 ; acid clean  34 ; rinse  36 ; tin plating  128 ; bismuth plating  130 ; tin plating  132 ; bismuth plating  134 ; fin plating  136 ; rinse  40 ; flux  138 ; reflow  140 ; unloading part  44 ; strip hooks  46 ; rinse hooks  48 ; and reload parts  13 . The differences in the alloy plating is that different baths are used for each metal (some baths  128 ,  132  and  136  for tin, and other baths  130  and  134  for bismuth). As can be appreciated by one skilled in the art, there could be one bath for each alloy or multiple alloys. Likewise, some alloy plating is achievable in a single tank (not shown). For tin/bismuth, five to seven layers achieve a good product, with the final layer being tin. The alloy weight composition can be regulated by the length of time in the various tanks or by the amount of direct current in the various tanks. If the same electrolyte is used in the tin tank and the bismuth tank, such as methane sulfonic acid, or fluroboric acid, then there is no need for rinsing between the tin and bismuth tanks. Alternatively, rinsing can be provided between plating tanks. If tin is the final plate, then there is no need for metal saving rinses, as tin is not considered an environmental hazard. Following plating of the metal layers, the articles/parts  12  pass through a flux spray  138  or flux bath and then to a heated reflow station  140 . The period of time in the reflow station  140  can be as short as a few seconds and be accomplished by infrared radiation, hot oil designed for reflow, or by vapor phase with solvent designed for such. Wash and dry steps might be required to remove residues from the reflow  140  step (not shown). The method of reflow will determine if wash and dry steps are required. Optimization of the length of time in the reflow station  140  is based on the amount of tin intermetallics with the basic material required for adhesion, and the thickness and number of the layers desired. According to the present invention, a reflow station serves several purposes, for example, but not limited to, to heat at least one metal on an artide thereby causing a melting of the at least one metal and/or causing a melting and/or fusing of at least two metals. Means for transferring heat to an artide comprise, for example, but are not limited to, use of heat transfer fluids and electromagnetic heating (e.g., eddy current heating and the like). 
     If the reflow time is too long, an increase in grain size may result along with some undesirable degree of alloy separation. For a reflow comprising hot oil, or another heat transfer fluid, reflow walls comprising a synthetic resin polymer, e.g., Teflon, are constructed and spaced to specific dimensions based on, for example, article dimensions and/or conveyor speed. Such walls also act to insulate the heat transfer fluid. With reference to FIG. 14, in most instances wall height exceeds article height to allow for flow of heat transfer fluid from at least one point near the top of the walls, e.g., ports  144 ,  144 ′,  144 ″,  144 ′″ shown in FIG. 14, while spacing between walls always exceeds article width. For example, a lead frame may have a width of approximately 0.010 inches and a printed circuit board may have a slightly thicker width—wall spacing will exceed such widths to allow for passing of the article. With reference to FIG. 14, heat transfer fluid flowing from the ports  144 ,  144 ′,  144 ″,  144 ′″ of the reflow walls  142 ,  142 ′ contacts the article and is subsequently collected in catch tray  146  or the like and transferred to a reservoir primarily or exclusively by gravity driven flow. The collected fluid is then available for recycle through the walls. In situations where synthetic resin wall material is inadequate, reflow walls comprise a different material, e.g., stainless steel. A different material is usable alone or in conjunction with a synthetic resin polymer, especially when the different material adds integrity and/or provides for flow channels within the wall. The surfaces of any construction material used are modifiable to reduce friction between the passing article and reflow wall. 
     In preferred embodiments of the present invention a reflow station, or reflow bath, comprises at least one wall comprising metal and/or synthetic resin polymer. Such walls may further comprise flow channels for flow of a heat transfer fluid. Again, any reflow station wall comprises a height greater than or equal to the artide height while another dimension of the wall is determinable in comparison to a width of the article, e.g., the widest horizontal dimension of the article. Of course, when two walls  142 ,  142 ′, as shown in FIG. 14, are present, spacing between the two walls exceeds a chosen dimension of the passing article. To further ensure ease of passage, at least one wall comprises friction reduction means for reducing friction between the at least one wall and the article. In addition, at least one wall may comprise insulation means to insulate heat transfer fluid, especially when the at least one wall insulates heat transfer fluid proximate to a passing article. In a preferred embodiment of the present invention, articles are submerged by heat transfer fluid when passing through a reflow station. 
     INDUSTRIAL APPLICABILITY 
     The invention is further illustrated by the following non-limiting example. 
     EXAMPLE 1 
     The present invention, as depicted in FIG. 1, was used to plate nickel onto steel parts. The conveyor speed was approximately 3-4 feet per minute, with  1-1.5 revolutions per minute of drive gear. The plater was run continuously for several months ( 3 shifts per day), producing hundreds of thousands of parts. The plater was 30′ in length with approximately 180 hooks. One flat part plated was for the bottom of a cellular phone charger. One angular part plated was a lever on a weedeater. The present invention was tested to 750 amps of direct current for nickel plating. Auxiliary brush or exposed cable contacts were placed approximately every 18″ to solve arcing problems. The processes shown in the flowchart of FIG. 2 were used for flat and angled parts. The parts had a hole in them which allowed for disposing the parts on the hooks. The nickel plating tank arrangement consisted of an approximately 300 gallon tank inside a 400 gallon tank. Anodes were placed in baskets. Each small rinse box (except for final rinse arrangement) was approximately 5″ long. The sizes of the various components were as follows: degreaser, electrocleaner and acid stations, 48″×12″ wide×8″ high; degreaser, electrocleaner and acid reservoir tanks, 60 gallons, 60″×18″ wide×16″ high; rinse boxes, 5″×9″ wide×9″ tall; rinse reservoirs, 16″×16″×16″, 17 gallon; rinse water flow, 3 gpm; nickel rinse reservoirs #1 and #2, 60″×22″×20″ deep, 110 gallon; nickel rinse reservoirs #3 and #4, 30″×22″×20″ deep, 55 gallon; and rinse box flows, 0.5 gpm, spray or laminar. A major benefit of the plater is it&#39;s ability to achieve thickness uniformity. Large, automated platers using racks to hold the articles are unable to plate with low standard deviations. 
     The preceding example can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding example. 
     Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above, are hereby incorporated by reference.