An electroless copper plating bath which is in the take mode is provided by determining the amount in the bath of at least four of the components selected from the group of oxygen, reducing agent, cyanide salt, cupric salt, and complexing agent; solving the equation:R=(CABD)/Ewherin C is the concentration of cupric salt, A is the concentration of reducing agent, B is the concentration of oxygen, D is the concentration of cyanide salt, E is the concentration of complexing agent, and R is a unitless number.The bath is provided with quantities of the above ingredients so that R in the equation is between about 5 and about 15.