Thermal stresses in a multilayered thin film thermoelectric structure

• A laminate model is presented for multilayered thin film thermoelectric structures.
• Thermal, electrical, and mechanical effects are coupled in the model.
• The model predicts much higher thermal stress than strength of material model.
• Effects of heat transfer at the film surfaces on the thermal stress are examined.
• The model provides a better tool in design for thermomechanical reliability.

This work investigates thermally induced stresses and deformations in a multilayered thin film thermoelectric (TE) structure for assessing thermomechanical reliability of the TE devices. The multilayered structure consists of a n-type and p-type thermocouple separated by an insulating layer, and an additional supporting membrane layer. The one-dimensional thermoelectricity is used to compute the temperature distribution with heat transfer by radiation and convection at the film surfaces being considered. The thermoelasticity theory of laminated composites is employed to determine the stresses and deformations in the thin film structure. It is found that the thermal stress calculated using the present laminate model has a significantly higher magnitude than that predicted by the strength of materials model. Effects of heat transfer coefficient at the film surfaces are also examined.