Interfiber orientation and volume fraction effects in electronic composite boards

Structural damages and failure of printed wiring boards or composite boards are likely to happen due to thermally induced high stresses. In this study, a combined thermal/structural finite element model is incorporated to obtain the predictions of the temperature and stress distribution of vertically clamped parallel circuit boards that include series of symmetrically mounted heated electronic modules (chips). The board is modeled as a thin plate containing four heated flush rectangular areas that represent the electronic modules. The finite element model should accept the convection heat transfer on the board surface, heat generation in the modules, and directional material properties inside the board. A detailed 3-D CFD model is incorporated to predict the conjugate heat transfer coefficients that strongly affect the temperature distribution in the board and modules. An FE model renders structural analyses that use the heat transfer coefficients as mentioned above, and structural elements capable of handling orthotropic material properties. The stress fields are obtained and compared for the models of different fiber volume fractions (Vf), and interfiber angles (?i), and for the boards made of two layers. Appreciable differences in stress and deformation fields and mild differences in the thermal gradient field were observed. Parametric field values vs. values of fiber volume fraction and interfiber orientation were analyzed and rendered metamodels that can be used in a more optimized or custom design of the boards with multiple plies.