The Effect of Convection on Electro-thermal Modeling of Whisker Shorting

Whisker growth from metal surfaces of electrical connectors and other components has shown itself to create reliability issues. If a whisker grows in a location that bridges between two conducting surfaces not previously electrically connected, a short can occur, resulting in faulting components. The current passing through the whisker will cause its temperature to rise due to Joule Heating. This can eventually cause the whisker to melt, which can than disconnect the short circuit. Therefore whisker shorts are limited by this melting current. Previous works have examined the coupled electro-thermal model of a solid whisker conductor, but most neglect the convection of heat into air, which dissipates some of the heat, reducing the temperature rise of the whisker. This work examines the influence of convection on the melting of a shorted whisker. This is done using a finite difference model that considers the temperature dependent conductivities when solving the coupled one-dimensional heat and electrical conduction equations. Since there exists a variety of metals capable of whiskering, various metal whiskers will be modeled here for comparison purposes.