Abstract: A control apparatus for automatically controlling at least the concentration of copper-ions, hydroxyl-ions and formaldehyde-ions in an electroless copper plating bath and independently analyzing, displaying and replenishing the concentration of each such ions whereby a sample for each of the ions is discontinuously removed from the plating bath and diluted with a specific amount of water and, independently of one another, the copper-ion concentration is colorimetrically analyzed, displayed and replenished as needed, the hydroxyl-ion concentration is potentiometrically analyzed, displayed and replenished as needed and the formaldehyde-ion concentration is amperometrically analyzed, displayed and replenished as needed.

Abstract: A two beam alternating light colorimeter is disclosed wherein a light beam passing through a lens system having a shutter is periodically deflected by a pivoting mirror. In a first non-deflecting position of the pivotable mirror a first measuring beam is created which passes through a first measuring cell and is guided to a common photo cell. In a second deflecting position of the mirror a second measuring beam is created which is guided through a second measuring cell to the same photo cell. Signals from the photo cell are connected through a controlled switching element to an analog memory. A computing circuit is provided which connects to an output of the analog memory and also to the photo cell. The switching element connects the first measuring signal to the analog memory when the mirror is in a non-deflecting position and opens when the mirror is in a deflecting position. The computing circuit compares the signals corresponding to the first and second measuring beams.

Abstract: A method for the automatic, electro-chemical determination of the end point of titration utilizing an initial, continuous addition of the titrant, up to a predetermined value, followed by a step-by-step addition with a resting time inserted therebetween for stabilization of the solution is disclosed. As the titrant is being added to the bath sample in constant volume units, a measured value is formed after every such addition. The difference to the preceding measurement is determined and the three consecutive differences of greatest magnitude are utilized in a mathematical formula for calculating the end point. The titration ceases when the greatest difference lies between two lesser values.