DETERMINATION OF Pd/Sn COLLOIDAL SEED ACTIVITY AND COMPONENT CONCENTRATION
Original Publication Date: 1988-May-01
Included in the Prior Art Database: 2005-Feb-15
This is an electrochemical technique for determining, on line, the catalytic activity and composition of a typical Pd/Sn colloidal seeder bath that is commonly used today in the manufacture of electronic circuit cards or boards. A combination of palladium and stannous, called "Pd/Sn sols", is used as a colloidal seeder to form a conductive film on the electrically non-conductive cards or boards. While there are techniques already today for measuring the catalytic activity of a Pd/Sn sol, none is known that can perform this measurement in situ on a manufacturing line. To monitor Pn/Sn seed activity: A glassy carbon (GC) rotating disk electrode (RDE) is immersed for one minute in a solution of colloidal seeder, at nominal bath concentration, followed by a one-minute immersion in HCl (8 vol%).