Humidity Effect on Chip Capacitors With Al2O3 Multistage Anodised Films
In this paper the properties of capacitors with porous-barrier and barrier-type Al2O3 layers under humidity tests are described and compared. The capacitance, conductance and dissipation factor of these structures were measured as a function of relative humidity ranging from 11% RH to 94% RH. It has been found that the dependences of electrical conductance on relative humidity on a log-log scale are linear with the slope from 0.026 to 8.19. For capacitors with the porous-barrier type layer the slopes were below unity in the whole humidity range while for capacitors with the barrier-type layer this was only true in the low humidity range (below 60% RH). The moisture effect on capacitors with solder bump and NiCr electrodes was extremely small. On the other hand the presence of chromium lying direct on Al2O3 film caused a rise in humidity sensitivity. The new ingenious technique of Al2O3 dielectric layer preparation proposed affords the possibilities of producing capacitors with very low sensitivity to moisture in both the low-and high-humidity ranges.