IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electronics Friday Sessions
       Session EL+SE+TF-FrM

Paper EL+SE+TF-FrM4
Laser Surface Treatment for Corrosion Prevention

Friday, November 2, 2001, 9:20 am, Room 131

Session: Laser Processing of Surfaces
Presenter: C. Georges, GREMI, France
Authors: C. Georges, GREMI, France
N. Semmar, GREMI, France
C. Boulmer-Leborgne, GREMI, France
C. Perrin, CERI, France
D. Simon, CERI, France
Correspondent: Click to Email
The materials used in electrical contact applications are constitued of a copper alloy (brass or bronze) covered with nickel coating (diffusion barrier) and with a gold coating. There are some porosities in the nickel and gold layers which induced corrosion of the underlying layers. To modify structure of gold coating, some laser surface treatments have been undertaken. An excimer laser is used as the photon absorption coefficient is larger in UV range and because the laser beam homogeneity is available for a surface treatment. The purpose of this surface treatment is to suppress the porosities of the gold layer which are responsible of the corrosion pits and to smooth the surface as the roughness bothers a correct electrical contact. The effects of the laser treatment are studied according to different surface parameters (roughness and composition of the substrate, thickness and composition of the gold coating). The laser beam parameter influence on surface melting is simulated by numerical code. Tests of corrosion are carried out in the humid synthetic air containing low contents of pollutants (NO2, SO2 and Cl2). The technique used to control these effects are : optical microscopy, SEM, grazing X-rays and ESCA. One dimension heat conduction is resolved to simulate the temperature time evolution and the melted depth as a function of the laser parameters (laser fluence, pulse time duration). This modelling helps to the understanding of mechanisms for laser interaction with the connector surface and will allows to determine the laser type to use for this appication.