Methods for Choosing a Saponifier or Surfactant for Printed Circuit Board and Stencil Cleaning Applications

摘要

This paper will discuss the technical challenges associated with the selection of chemical additive for the printed circuit board assembly (PCBA) and stencil cleaning processes. The removal of residues from lead free and tin lead fluxes are increasingly causing problems for printed circuit board (PCB) assemblers. The heat requirements of lead free chemicals have made removing the residues difficult, and all residues can cause problems with components that have decreased in size and those with increased electrical sensitivity. The problems associated with residues exist with both lead free and tin lead organic and rosin based chemicals. Residues from organic chemicals can cause corrosion or lead to electrochemical migration. Residues from rosin based no clean chemicals can cause problems with the application of conformal coatings, test connections, and high frequency components. The practice of using of high purity deionized water has been unsuccessful in removing many types of residues and can actually contribute additional problems.For these situations, additional chemical additives, such as saponifiers and surfactants, can be used to assist in removing hard to clean residues. These additives are used in all style of cleaners such as in-line, batch style, and stencil cleaners. Because not all additives have the same formula and can be used with all cleaning processes, manufacturing locations must decide which additive can be used to clean the residues in question and meet local environmental regulations. The cost of the additive must also be considered. Since the use of chemical additives is a large investment for manufacturing facilities, the correct type and concentration must be determined to achieve the appropriate cleanliness level for the least amount of investment.