EFFECTS OF N,N-BIS(POLYOXYETHYLENE)OCTADECYLAMINES ON THE ELECTROCRYSTALLIZATION OF TIN FROM ACID STANNOUS SULFATE-SOLUTIONS

The electrochemical characteristics of three kinds of N,N-bis(polyoxyethylene)octadecylamines (POOA) and the effects of POOA on the surface morphology as well as crystal orientation of electrodeposited tin from acid stannous sulfate solutions have been studied by means of various electrochemical methods, scanning electron microscopic observation and measurements of X-ray diffraction patterns. The three kinds of POOA were adsorbed on the electrode in the range of potentials from 0 to - 1.50 V, and POOA adsorbed on the electrode inhibited the electrochemical reduction of tin(II) ion. Needle-like, or columnar, electrodeposits of tin were obtained from acid stannous sulfate solution in the absence of organic additives. On the other hand, block-like or granular crystals which exhibit the (101) plane parallel to the surface were observed on the whole surface by adding POOA. It was found that the three kinds of POOA induce a uniform deposition of tin over the whole surface, and the grain size of crystals as well as the surface roughness of electrodeposited tin become smaller with increasing the chain-number of oxyethylene in POOA.