2,808
edits
Changes
→13.2.1.2 Porosity
Pores are surface defects which may have multiple causes. These include roughness and defects in the substrate layer or material such as grooves or
scratch marks, as well as cracks in the base material which may have been generated by bend stresses or mechanical wear ''<xr id="fig:Porosity of an electroplated hard gold layer"/> (Fig. 13.1)''.<figure id="fig:Porosity of an electroplated hard gold layer">[[File:Porosity of an electroplated hard gold layer.jpg|right|thumb|Porosity of an electroplated hard gold layer as a function of the layer thickness at different surface roughness values R<sub>a</sub>]]</figure>
At the foot points of the pores the substrate material is exposed to the surrounding atmosphere. This can cause corrosion products to rise through the pores to the contact surface, expand there further, and thus lead to increased contact resistance. The allowable number of pores in gold layers, for example for connectors, mainly depends on the concentration of corrosive gases in the intended working environment.
