A chemical control system for controlling the chemistry of a chemical
solution having predetermined chemical constituents in a plating system,
such as a NiFe plating system, employs a mix container for containing a
plating solution and a hold container for containing a plating solution
delivered from the mix container. A precision delivery arrangement
delivers a precise predetermined quantum of a predetermined constituent
of the plating solution to multiple mix containers and the hold
containers. Transfer of plating solution between the mix and hold
containers is effected by a transfer pump. Nitrogen gas that has been
humidified with deionized water protects the plating solution from either
acquiring water or becoming dehydrated, the humidified nitrogen gas being
humidified to a predetermined relative humidity with respect to the
temperature of the plating solution in the mix container. This is
achieved by urging the nitrogen gas through a column that is at the same
temperature as the plating solution. Precise delivery of the chemical
constituents is achieved by a pneumatic pump arranged serially with an
orifice and an inexpensive flow meter. The pneumatic pump is a positive
displacement, double diaphragm pump.