Device and process for controlling the efficiency of a metal electrodeposition bath

Abstract

Arranged in a bath contained in a tank are respectively an anodic electrode and a cathodic electrode, which are connected to an electric current generator. The cathodic electrode can be composed of a plurality of individual test specimens suitable for being immersed in the metal bath, and the device additionally includes a controllable electric power supply unit for the individual cathodic test specimens, which is connected to the current generator and includes a mechanism for controlling the current passing through the cathodic test specimens so that a given current flows in each of them.

1 - 10 . (canceled) 
     
     
         11 : A device for testing efficiency of a metal electroplating bath contained in a tank, or for testing efficiency under conditions for producing plated workpieces, the device comprising:
 electrodes, respectively anodes and cathodes, connected to an electrical-current generator, the cathode including a number of individual samples configured to be submerged in the metal electroplating bath and supplied with power by an electrical power supply that is controllable and connected to the current generator and that comprises means for adjusting the current flowing through the cathode samples so that in each of the samples a given current flows,   wherein the individual cathode samples are suspended from a sample holder placed above the metal bath in the tank so that practically only the samples are submerged in the bath.   
     
     
         12 : The device as claimed in  claim 11 , in which the sample holder can move vertically, so as to lower and raise the samples relative to the tank, and horizontally in the bath of the tank. 
     
     
         13 : The device as claimed in  claim 11 , in which the current-adjusting means of the electrical-power-supply unit are defined, for each cathode sample, by a variable resistor connected on one side to the current generator and on the other side to the corresponding cathode sample. 
     
     
         14 : The device as claimed in  claim 13  in which, between each variable resistor and its corresponding cathode sample, an instrument is provided for measuring current flowing into the sample. 
     
     
         15 : The device as claimed in  claim 11 , in which the individual cathode samples are a same size and disk shaped. 
     
     
         16 : The device as claimed in  claim 11 , further comprising means for stirring the metal bath associated with the tank. 
     
     
         17 : The device as claimed in  claim 11 , in which, for the bath in the tank, two anodes taking the form of parallel grids or plates are provided, between which the cathode samples are arranged. 
     
     
         18 : The device as claimed in  claim 11 , in which the individual cathode samples are arbitrarily arranged in the bath or are aligned and regularly spaced apart from one another in one and a same horizontal plane. 
     
     
         19 : A method for testing efficiency of a metal electroplating bath contained in a tank, or under conditions for producing plated workpieces,
 using the testing device as defined in  claim 11 , and comprising:   weighing the individual cathode samples before they are placed on the moveable sample holder of the device;   suspending the samples from the sample holder;   submerging the suspended samples in the electroplating bath;   individually subjecting the samples to a chosen, adjustable current;   removing the samples from the bath using the moveable sample holder once a metal coating has been deposited on the samples; and   weighing the coated samples so as to determine the weight of the coating deposited on each sample.   
     
     
         20 : The method as claimed in  claim 19 , in which, after the coated samples have been weighed, efficiency graphs are produced for each tested bath, the graphs showing a deposition rate as a function of current density in each sample and, if required, the efficiency graphs obtained during testing of the bath are used to modify at least one of the bath parameters, so as to deposit coatings on workpieces under optimal production conditions.