ION chromatography component specific cleanliness testing for process acceptability

Surface mount electronic components, whose external connections consist of metalized terminations, are an integral part of today's highly dense printed circuit board assemblies. Bottom terminated components identified as QFN, DFN, SON, MLP, MLF, TQFN and VQFN contain a large amount of solder under the component termination. When incorporating BTCs into a design, it is essential to maximize a variety of parameters including first pass assembly yields and quality levels to ensure the long-term function of the device. Since there is no protruding lead on the package, the metal connection areas and standoff height can impact the level and activity of flux residue under the bottom termination. The growing complexity of these devices in combination with larger solder mass per surface area and higher interconnection densities increase the risk of in-field failures. The levels of ionic residue present under the bottom termination must be defined, qualified and controlled. The purpose of this research is to test the feasibility of performing Ion Chromatography at the component site to obtain an accurate assessment of contamination present under the bottom termination. Component-specific test boards developed for both localized IC and SIR testing will be used to quantitate ionic residue levels using site-specific extractions.