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Interfacial adhesion thru surface roughening technique has become the focus subject in this new packaging era. Though it is a widely used technology in leadless packages, there are no works conducted on leaded packages. Our first attempt on chemical lead-frame treatment is on SOT package. To perform surface treatment on leaded packages by a simple chemical dip would not be possible because the protruding leads will be treated as well. To exacerbate this issue further, SOT package do not have any dambar that prevents the molded flash from running along its entire external lead length. This imposes difficulty in solderability of the end product. Improvisation was done on HPWJ and deflashing method to remove the mold flash/bleed prior to plating. However, control at surface treatment stage is most crucial in order to ease flash/bleed removal at HPWJ. The treated surface narrowed to be within the package internal only. This helps to ensure the bleed adhesion to the leads is prevented. Triple belt with burr up found to be effective in controlling the chemical bleed to the leads sides.
Date of Conference: 3-5 Oct. 2007