Different packaging configurations in BaTiO3-epoxy composite to model their dielectric constant

L. RAMAJO; D. RAMAJO; D. SANTIAGO; M. REBOREDO; M. CASTRO

Toledo

Congreso; Electroceramics X; 2006

CSIC - Sociedad Española de Cerámica y Vidrio

Integral capacitors (IC) for two-layer printed wiring board (PWB) circuits can be produced using comb electrodes. Nevertheless, the main problem is the difficulty to predict their behaviour for real-geometry devices. If the interdigitated electrodes portion is sufficiently large, the structures can be approximated by a semi-infinite system and the calculation through analytical or simplified numerical methods can be obtained. However, in electronic applications, the specific capacitance of the structure needs the exact determination of the electrodes configuration. In this way, the effective capacitance of simples 2D and 3D models can be obtained employing the finite element method (FEM). In this work, IC capacitors made with comb electrodes and dielectric composite materials (BaTiO3 -epoxy) were modelled by FEM. The dielectric response of these capacitors was evaluated by means of a quasi-static approximation applying the Laplace equation and solving it by FEM (2D and 3D geometries were used). The numerical results were confronted with experimental dielectric measurements of samples prepared by dipping technique. The data were obtained varying the temperature from 20ºC to 60ºC and the frequency from 20Hz to 1MHz. Results showed that IC dielectric properties can be estimated very well but the edge effects turn to be important in smaller capacitors.