Issue link: https://iconnect007.uberflip.com/i/978458
56 PCB007 MAGAZINE I MAY 2018 Surface Preparation and Cleaning, Part 2 Trouble in Your Tank by Michael Carano, RBP CHEMICAL TECHNOLOGY Some type of cleaning and surface structur- ing is required in virtually every step of the printed circuit manufacturing process, from preparing the raw laminate for etch or plating resist to final assembly board cleaning before shipment. In this edition of "Trouble in Your Tank," I will attempt to cover most of the gen- eral cleaning problems that can occur in any of these steps and, where possible, any prob- lems unique to a specific manufacturing step. Many cleaning procedures are tightly integrat- ed within certain manufacturing processes, such as plating, and may also be covered in other columns or feature articles. This section is divided into two categories: mechanical cleaning surface preparation and chemical cleaning. Howev- er, this is only a general pre- sentation. More de- tails with chemi- cal and mechanical cleaning will be covered in future columns. One should make a clear distinction between the method of surface preparation and the na- ture of the surface alteration affected by such a method. The mechanical method of brush scrubbing changes the topography as well as the chemical composition of the surface (e.g., removal of oxide, chromium, etc.). On the oth- er hand, the mechanical method of jet-pum- ice scrubbing restructures the topography with little or no abrasion of copper. The chemi- cal composition of the surface stays very much the same, except for the removal of loosely held oxide and some redistribution (e.g., of chromium from con- version coatings into deep- er layers of the surface). A chemical surface prepara- tion method such as