Abstract:
Device ( 60 ) having one or more operative units ( 55 ) for electroplating a film by chemical reaction with a specially made liquid product ( 29 ) and application of direct current, on sheets ( 50 ) for printed circuits continuously translating between one or more pairs of opposing oblong chambers ( 210, 130 ) respectively supplied with tubular nozzles ( 231 ) and with one longitudinal slit nozzle ( 233 ) and having internal electrodes ( 220, 240 ) electrically connected to the negative pole of a generator of direct current, between one or more pairs of titanium contact rollers ( 61-62, 130-131 ), electrically connected to the positive pole of the current, and plastic containment rollers ( 100-101, 110-111 ) of the liquid ( 29 ) rotating in each pair reciprocally in opposite directions, due to closure of the electric circuit between the liquid product ( 29 ), pumped in under pressure by the pump and projected by the nozzles ( 213, 233 ) of the chambers ( 210, 230 ) against the sheets ( 50 ), and said sheets through the contact rollers.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns equipment and automatic systems for electro-plating on metal sheets especially for the production of printed circuits. 
     To apply a protective or antioxidant film to the sheets or in any case a film designed to improve their quality, the sheets are immersed in a special bath. The components of the bath cause chemical reactions on the metal surface, especially on copper, producing a film of what is known as chemical tin, or chemical copper as the case may be, or other products. 
     For large-scale production specially devised mechanical means of transport pass the sheets through the bath one after another. 
     The procedure, based on a chemical reaction associated to the action of gravity, obviously takes considerable time partly because of the need to obtain an even film. 
     SUMMARY OF THE INVENTION 
     Purpose of the above invention is to shorten working times while ensuring optimum formation of the film on the sheets as will now be explained. Subject of the invention is a device, in a plant for electoplating a film on metal sheets, especially for printed circuits, translating continuously, parallel one to another, using special transporting means. 
     This device presents, in succession, one or more operative units each comprising one or more pairs of metal rollers, here called contact rollers, carrying along in axial rotation by mechanical means, reciprocally in the opposite direction, sealed oblong chambers, placed above the trajectory of the translating sheets, having a series of tubular nozzles with coplanar axes substantially side by side and parallel, provided with an internal oblong laminar electrode, a pump that continuously takes up a special liquid product recycled from a bath underneath and pumps it under pressure into said chambers, the device being connected to an electric-electronic drive unit which, in accordance with a specially devised program, controls and operates the movement of said rollers, action of the pump, translation of the sheets and generation of direct electric current. 
     Said pairs of rollers and said chambers are placed transversally to the direction of translation of the sheets. 
     The electrode inside the sealed chamber and said contact rollers are reciprocally electrically insulated and respectively connected to the two poles of said direct current. 
     As the sheets pass between the pairs of contact rollers the liquid pumped into the chamber is projected through the nozzles onto the areas of the sheets while these emerge from said rollers. 
     It follows that, due to the effect produced by closure of the electric circuit generated by the DC current between the liquid and the sheets, these latter become electro-plated as desired. 
     After the pair of contact rollers and before the oblong chamber, bearing in mind the direction of movement, each operative unit comprises, in succession, a first pair of rollers, here called containment rollers, resting laterally one above another and drawn along in axial rotation, reciprocally opposingly directed, by mechanical means. 
     The upper roller is surrounded by a number of substantially equal rings placed side by side, whose internal diameter is considerably larger than the diameter of said upper roller. 
     Associated to said first oblong chamber with tubular nozzles is a second oblong chamber opposite to the first and placed below the trajectory of the translating sheets. 
     Said second chamber is substantially similar to the first one but, instead of tubular nozzles, it has a nozzle with a narrow longitudinal slit in it substantially opposite to the set of nozzles of the chamber above and extending to the same length as that of said set. 
     The second chamber is also supplied by the pump with recycled liquid from the bath below, and has inside it a laminar oblong electrode connected to the same electric pole to which the electrode of the first chamber is connected. 
     After said pair of chambers there is a second pair of containment rollers substantially equal to the first pair. 
     The upper chamber is placed higher than the upper rollers comprised in the two pairs of containment rollers. 
     The lower chamber is placed lower than the axis of the lower rollers of said two pairs of containment rollers. 
     The level and reciprocal distance of the longitudinal edges of the upper faces of said lower chambers are such as will ensure contact between the surfaces of said lower rollers and said edges thus forming a kind of intermediate channel comprising a base, formed of the upper face of said lower chambers, and sides formed of the opposite surfaces of said lower rollers forming the two pairs of containment rollers. 
     Said channel therefore becomes filled with the liquid that emerges under pressure through the slit nozzle for the lower chambers. 
     When the rings of the upper rollers in said pairs of containment rollers spontaneously rest on the surfaces of the advancing sheets, they sub stantially form a channel whose base is formed by the advancing sheets and whose side walls are formed by the external surfaces of said rings. 
     This channel too fills up with active liquid from the nozzles of said upper chambers. 
     Each operative unit advantageously comprises, between the pairs of contact and containment rollers, a freely turning pair of rollers here called finishing rollers. 
     The rollers of each pair are respectively served by supports formed of rectangular recesses made in the opposite sides of the framework of the installation into which recesses the pins and cylindrical extensions to the two ends of said rollers can fit. 
     Due to its own weight, therefore, the upper roller of each pair of rollers bears on the lower roller and consequently on the metal sheets when they pass between said rollers. 
     The mechanism that rotates the pair of contact rollers comprises gear wheels fixed to the ends of the lower rollers of the pair, said gears meshing with a continuous chain placed orthogonally to said rollers and driven by an electric motor. 
     The rollers of each pair are linked by substantially similar gear wheels. 
     Even though the upper roller in the pair of contact rollers is slightly separated from the lower one by passage of the metal sheets, its rotation is assured by the length of the teeth of the gear wheels, these being considerably longer than the thickness of said sheets. 
     The mechanism that causes rotation of the pair of containment rollers comprises helical gear wheels fixed to the opposite ends (in relation to the ends of the contact rollers) of the lower rollers in the pair, these gears meshing with the helical gear wheels fixed to a motor driven shaft orthogonal to said rollers. 
     The two rollers of each pair are linked by substantially equal helical gear wheels. 
     The contact rollers and the laminar electrodes placed inside the sealed chambers are respectively connected electrically to the negative and positive poles of the direct current. 
     Should it be required to have electro-plating on oblong sheets with raised edges of plastic material, the contact finishing and containment rollers are made with annular bands, of a width corresponding to that of said oblong sheets, between said edges and projecting above the height of said edges on both faces of said sheets. 
     The dimensions of the rings round the containment rollers and of the internal and external diameters, as well as width, are calculated to allow them to settle spontaneously both on the faces of the sheets and on the raised edges. 
     The film may be of chemical tin or of chemical copper or may possess other characteristics. 
     The contact rollers are advantageously of titanium. 
     The finishing and containment rollers and the rings round said latter rollers are advantageously of plastic material. 
     The invention offers evident advantages. By closure of the direct current electric circuit between the active liquid, receiving a polarity from the electrodes in the sealed chambers with nozzles, and the sheets receiving the second polarity from the titanium rollers, deposition times of the particles in the liquid and of the chemical reactions that form the film on both faces of the sheets are greatly accelerated. 
     All this is accompanied by a reduction in the costs of manufacturing printed circuits especially, and by a considerable improvement in quality. 
     Characteristics and purposes of the disclosure will be made still clearer by the following examples of its execution illustrated by diagrammatically drawn figures. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 Installation showing the device subject of the invention for electro-plating in line, on metal sheets especially for printed circuits, with a number of operative units, side view. 
     FIG. 2 Cross section of the device upstream of a first operative unit. 
     FIG. 3 Cross section of the device upstream of the containment rollers of said operative unit. 
     FIG. 4 Detail of an operative unit, lateral perspective from above. 
     FIG. 5 Detail of an operative unit in a different version for oblong metal sheets with raised edges of plastic material. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The installation  10  with framework  11  for electro-plating on sheets, especially for printed circuits, in movement, is programmed and operated by an electric-electronic drive unit  12  with control panel  13 , comprising a current rectifier  15  with control panel  16  that supplies low voltage direct current, and the motor  17  for translation of the sheets  50 . 
     The installation comprises a channel  18  within which the sheets  50  move on a horizontal plane XX and, in succession, four groups, for preparation  20 , for electro-plating  30 , for washing  38  and for drying  45 . 
     The preparation group  20  comprises the degreasing stations  21 , washing stations  22  and pickling stations  23 . 
     Said stations exhibit a series of upper  24  and lower  25  nozzles, the pumps  26 , heat generators  27  and valves  28 . 
     The electro-plating group  30  comprises a device  60 , subject of the invention, the heat generator  33 , pump  32 , cold generator  31 , solenoid valve  34 , impurity collecter  35  and valves  36 . 
     The washing group  38  comprises a set of upper nozzles  41 , lower nozzles  42 , pumps  39  and valves  40 . 
     The drying group  45  comprises a blower  46 , fume chimney  47  and a series of nozzles  48  for drying the sheets  50 . 
     The electro-plating device  60  comprises a series of operative units, like  55 - 57 , these in turn (as shown in unit  55  in FIG. 4) comprising a pair of titanium rollers, called contact rollers, an upper one  62  and a lower one  61 , a pair of rollers, here called finishing rollers, an upper one  91  and a lower one  90  of plastic material and a pair of rollers, here called containment rollers, a lower one  100  and an upper one  101  of plastic material. 
     The upper roller  101  of the pair of containment rollers  100  and  101 , is surrounded by a series of containment rings  106  free to rotate on said roller, their internal diameter being substantially greater than the external diameter of said roller  101 . 
     At a certain horizontal distance from the pair of containment rollers  100  and  101 , there is a second substantially equal pair of containment rollers comprising an upper roller  111  and a lower roller  110   
     The upper roller is surrounded by a number of rings  116  substantially equal to the rings  106 . 
     Downstream of said second pair of containment rollers is a second pair of finishing rollers  120  and  121   
     Downstream of said second pair of finishing rollers is a second pair of contact rollers  130  and  131 . 
     Said electro-plating device  60  presents two opposing sides  201 ,  202 , inside of which are the opposing plates  160  and  170  that support the rollers of the operative units like the one already described. 
     The upper roller  62  of the first pair of contact rollers has two pins  65  and  66  at its two ends. 
     The lower roller  61  of said pair presents the pin  63  at one end and at the other end a pin  64  that extends nearly as far as the side  202  and has at one end the axial slot  70  for insertion of the tongue  71  of a short shaft  72  supported by roller bearings  80  placed in said side  202 . 
     The pin  63  and the initial part of pin  64  freely penetrate inside the substantially rectangular seats  161  and  171  made in the opposing support plates  160  and  170  referred to above. 
     The pins  65  and  66  of the upper roller of said pair of contact rollers are similarly lodged in said seats  161  and  171  in which they can freely slide. 
     The upper roller  62  therefore weighs on the lower roller  61  while allowing free passage between them for the translating sheets  50 . 
     The containment rollers  100  and  101  respectively present pins  102  and  103 , pin  105  and the extension  104  of the upper roller  101 . 
     Said pins  102 ,  103 ,  105  and said extension  104  freely penetrate inside the substantially rectangular seats  162 ,  172 , made in the support plates  160  and  170 . 
     The pins on the lower roller  100  are supported by the base of said seats  162  and  172  while the pins  104  and  105  of the upper roller  101  can slide freely inside said seats  162  and  172 . 
     Fixed to the extension  73  of the shaft  72 , mounted on the lower roller  61  of the pair of contact rollers  61  and  62 , is a gear wheel  151  that meshes with the continuous chain  150  moved by an electric motor not shown in the figures for the sake of simplicity. 
     The gear wheel  76  is mounted on the pin  64  of said roller  61 , this gear wheel meshing with the gear wheel  77  mounted on pin  66  of the upper roller  62  of said pair of rollers  61  and  62 . 
     Said roller  62  is therefore made to rotate by the roller  61 . 
     As the upper roller  62  freely gravitates on the lower roller  61  and allowing for the length of the teeth on the gear wheels  76  and  77 , rotation of said rollers makes possible free passage of the thin metal sheet  50  to be electro-plated. 
     The other pairs of contact rollers, like  130 ,  131  and others, are similarly made to rotate by the gear wheels  152 ,  153  and others that mesh with the continuous chain  150  already mentioned, fixed to the extended pins  132  and  142  of the lower rollers of the pair of contact rollers such as  130  and others. 
     At one end  102  of the lower roller  100  of the pair of containment rollers  100  and  101 , is the gear wheel  107  with helical teeth that meshes with the helically toothed wheel  156  on the shaft  155  orthogonal to said rollers and parallel to the trajectory followed by the metal sheets. 
     The gear wheel  108  is mounted on the pin  104  of the upper roller  101  of said pair and is substantially the same as gear wheel  107  with which it meshes. Rollers  100  and  101  therefore rotate in opposite directions. 
     The other pairs of containment rollers, like  110  and  111 , are similarly made to rotate by the gear wheels  117  and  118  respectively fixed to the ends  112  and  113  of said rollers, and by gear wheel  157  fixed to the shaft  155 . 
     Placed between the second pair of containment rollers and the second pair of contact rollers is a second pair of finishing rollers  120  and  121 . 
     Extensions  73  to the short shafts  72  rotate inside grooves  183  in the opposing bars  181  and  182  supported by U-shaped pieces  190  and  191  forming part of the electrical unit  180 . 
     The two bars  181 ,  182  are electrically and mechanically connected by a flexible U-bolt  184  fixed by means of tabs  185 . 
     Bar  182  is pressure mounted against said extensions  73  to shafts  72  by the compression springs  193  placed between the supports  192 , fixed to the frame of the plant, and the U-shaped piece  191 . 
     Bar  181  presses with its weight on said extensions  73  strengthening contact thereby, and is electrically connected by the wire  186  to the generator  15  of direct current. 
     Placed between the two pairs of containment rollers, respectively  100 - 101  and  110 - 111 , are oblong opposing sealed chambers, an upper chamber  210  and a lower chamber  230 , with parallelepiped body  211  and covers  212  and  232 . 
     On its lower face opposite the translating metal sheets, the chamber  210  has the tubular nozzles  213 . 
     Said chamber communicates with the pump  32  through the beak  214  and a suitable connecting tube  215 , and is supported by the vertical plate  202  by means of the horizontal metal bracket  251  with ends  252  at 900. 
     Said bracket is connected to the oblong electrode  220 , placed inside said chamber, by bolts  221  and nuts  222  and  223 . 
     The end  252  of the bracket  251  is fixed to the metal sides  202  of the frame  11  of the installation, by means of a bolt  255 , bushing  253  and insulating washer  254 . 
     The electrode  220  can therefore be connected to the generator  15  of direct current by wire  257  thus forming the electrical unit  250 . 
     The chamber  230  is substantially the same as the chamber  210  except that, instead of the tubular nozzles  213 , there is a longitudinal nozzle  233  having in it a slit  236 , said nozzle extending for practically the whole length of the series of nozzles  213  for the upper chamber  21   0 , and being substantially in line with said upper nozzles. 
     On the upper plane of chamber  230 , facing towards the metal sheets that translate above it, are edges  235  and  237  that remain substantially in contact with the surfaces of the lower containment rollers  100  and  110  in the pairs of containment rollers  100 - 101  and  110 - 111 . 
     It will be clear from the above how the electro-plating device works. 
     As seen in FIG. 1, said electro-plating device comprises a set of operative units  55 - 57  like unit  55  described in more detail. 
     Said operative units  55 - 57  are seen in diagrammatic form in the general FIG. 1 of the installation with only the first pair of contact rollers, like  61  and  62 , of sealed chambers  210  and  230 , the second pair of contact rollers like  130  and  131 , a second pair of chambers  210 ′ and  230 ′, a third pair of contact rollers  130 ′ and  131 ′, a third pair of sealed chambers  210 ″ and  230 ″ and a fourth pair of contact rollers  130 ″ and  131 ″. 
     The sheets  50  that move along line XX towards the first operative unit  55 , pass, as also seen in FIGS. 2-4, between the rollers  61 ,  62  of the first contact pair, between rollers  90 ,  91  of the first finishing pair, between rollers  100  and  101  of the first containment pair, by action respectively of the active liquid  29  emitted from above by the tubular nozzles  213  of the sealed chamber  210 , and from below through the nozzle with slit  233 , of the first pair of sealed chambers, between the rollers of the second pair of containment rollers  110  and  111 , between the rollers of the second pair of finishing rollers  120  and  121 , between the rollers of the second pair of contact rollers  130   131  and then by action from the successive operative units such as  56  and  57 . 
     Between the lower rollers of the pair of containment rollers  100 ,  110 , placed either side of the pair of sealed chambers, such as  210  and  230 , due to contact between the longitudinal raised edges  235  and  237  of the lower chamber and the surfaces of said lower rollers  100  and  110 , a lower channel is formed in practice bounded by the lower plane (of the lower sealed chamber), by the surfaces of the aforesaid two lower rollers and by the advancing sheets  50 , which channel, fed by the liquid emitted especially by the nozzle  233  with a slit  236  in it, is kept full of active liquid  29  thus helping to reinforce the electro-plating action under the sheet  50 . 
     Between the upper rollers of the pairs of containment rollers, surrounded by the rings  106  and  116  and the sheets that pass between said pairs of rollers, due to presence of said rings, that maintain contact with the upper face of the advancing sheets  50 , a sort of upper channel is created the base being formed by the advancing sheets and the walls by the external surfaces of the rings  106 ,  116  on said upper rollers, which channel, fed through the nozzles  213  of the upper chamber, is kept full of active liquid emitted by said nozzles. 
     The electric unit  180 , formed of the bars  181  and  182  electrically connected to the pairs of titanium rollers  60  and  61 ,  130  and  131  and successive ones, is connected to the negative pole of the generator  15  of direct current while the active liquid, pumped under pressure by the pump  32  into the pairs of sealed chambers  210  and  230  and successive ones becomes charged, due to electrodes  220  and  240 , as a consequence of connection of the electric unit  250  comprising said electrodes, to the positive pole of said generator  15  of direct current. 
     Electro-plating is thus made more effecient by the synergetic and interacting effect of the projection of active liquid on both faces of the advancing sheets, by formation of a volume of said liquid both below and above said sheets and by closure of the electric circuit between said active liquid and the sheets  50  electrically charged by the titanium contact rollers  61  and  62  and by the others described. 
     FIG. 5 illustrates a variant of the operative units appropriate for electro-plating on oblong sheets  52  to whose longitudinal edges the plastic strips  53  have been applied so making ridges on the two faces of said sheets. 
     The operative units described are varied by replacing the pairs of rollers described with others provided with raised bands of a width corresponding to the width of the sheets between the ridges and of a height greater than the thickness of said ridges on said oblong sheets  52 . FIG. 5 shows said new operative units. 
     The first pair of lower  260  and upper  261  contact rollers respectively carry the raised bands  262  and  263 . 
     The lower  270  and upper  271  finishing rollers respectively carry raised bands  272  and  273 . 
     The lower  280  and upper  281  containment rollers respectively carry the raised bands  282  and the rings  283 . 
     The second pair of lower  285  and upper  286  containment rollers respectively carry the raised bands  287  and the rings  288 . 
     Said rings are suitably sized to pass between the raised edges of each sheet for contact both with the faces of said sheets and with said ridges. 
     The second pair of finishing rollers  275 ,  276  and the second pair of contact rollers  265 ,  266  carry the raised bands already described. 
     Placed between the pairs of containment rollers is the pair of sealed chambers with upper nozzle  210  and lower nozzle  245 . 
     The upper plane of said lower chamber has longitudinal edges  246  and  247  shaped to fit with containment rollers  280  and  285 . 
     Optimum electro-plating can therefore be carried out as for the flat sheets.