300 s to 1800 s the temperature or the plating bath is held during plating in a range from 40 u00b0 c to 95 u00b0 c more preferably 60 u00b0 c to 85 u00b0 c optionally the tin or tin alloy deposit is post treated with an anti tarnish composition the composition comprising a phosphorous containing compound rinsing with water between each process step is suitable the invention will now be illustrated by reference to the following non limiting examples printed circuit board substrates having surface areas made of copper were micro etched with a solution comprising sulphuric acid t 35 u00b0 c t 1 min rinsed with water and then immersed in an autocatalytic tin plating bath t 70 u00b0 c t 15 min stirring rinsed with water again and dried t 60 u00b0 c t 15 min the thickness of the deposited tin layer was determined by x ray fluorescence xrf measurements the plating rate was calculated by dividing the tin layer thickness by the plating time a plating rate of at least 0 5 u03bcm 15 min is required for practical applications the plating bath stability was further rated by stability numbers in five classes wherein 5 resembles to a very stable tin plating bath i e no undesired precipitation of plating bath ingredients or metallic tin occurs during use of the plating bath and 1 resembles to an unstable plating bath wherein an undesired precipitation of metallic tin occurs before or during heating up the plating bath to the desired plating bath temperature of 60 u00b0 c an autocatalytic tin plating bath containing 7 6 g l sncl 2 51 ml of an aqueous ticl 3 solution 15 wt ticl 3 10 wt hcl 184 8 g l potassium pyrophosphate 38 8 g.