Text Box: Electroless Copper Text Box: Principle of Operation A circulating pump takes a solution from the electroless copper  tank to be controlled.  The sample is passed by a thermistor to measure the temperature and then to a colourimeter to determine the copper content.   A small sample is then taken from the main stream and fed to a pH electrode.  A standard HCl solution is mixed with the stream to obtain a fixed pH by a variable speed pump.  The hydroxide content is determined by the speed of the HCl pump.  The mixture is then sent to another pH electrode.  A standard sodium sulphite solution is then mixed with this stream to obtain a fixed pH at the second electrode, by a further variable speed pump.  The formaldehyde content is determined from the speed of this pump.    If the copper, hydroxide or formaldehyde concentrations are below user defined limits the controller activates electrical outputs to feed fresh replenishment chemistry to the process tank.  Separate pumps are activated to replenish the copper, hydroxide or formaldehyde containing components.   An alarm system indicates if any of the parameters are out of specification   Text Box: > Digital display > Custom designed microprocessor for reliability and simple operation > Data logging system and optional printer / data interface > Comprehensive alarm system to indicate an out of spec process Text Box: > Accurately measures copper, hydroxide and    formaldehyde content in electroless copper systems > Temperature compensation for accurate readings > Adds fresh replenisher as required to ensure a steady    plating rate.  Copper, caustic and formaldehyde    replenishers are added independently > Easy to set up Text Box: Titrating Three Channel Electroless Copper Control System Text Box: