Abstract:
Various packages being used for electronic card assemblies and flat pin as well as dual inline packages are mostly employed. The package pins are coated with nickel followed by gold layer and thicknesses ranging from 1-3 um. The coating not only prevents corrosion due to environmental effect but also takes care of scratches. As the coating thickness is less so the storage conditions plays an important role in keeping the packages intact. Due to improper storage or handling, various contaminants can deposit and stuck due to humidity resulting it in stain which in result may affect long term reliability of packages. The stain can be due to volatile or organic contaminants and needs to be cleaned so as to utilize the component for high reliability applications. Traditionally the stains are cleaned with Iso-propyl Alcohol (wet method) and abrasive cleaning (dry method) through powder which poses lot of constraints as it is performed manually. Apart from that as packages comes with multiple pins having small pitch and width so extra precaution to be taken so as to avoid Electrostatic discharge (ESD), roughness, breakage. This leads to higher time consumption and sometime multiple abrasion which can be detrimental to device long term reliability. To circumvent the same, microwave plasma technique is introduced which leads to stain removal totally avoiding manual operations.Optimization of the power and time is needed so as to remove the stains completely. This article details the recipe optimization of the microwave plasma and the detailing various observations using optical microscope.
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